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Senior Design II Documentation - University of Central Florida

1. P2zz zZz i sisa o000 __ coo PICAKE18 LED3 LED2 LED1 yo Ve y i Section 8 3 Wireless Communication The robot is to be controlled wirelessly by a conventional Playstation 2 controller that is the version equipped with the cable Using the Playstation 2 controller the user will be able to control the movements the gait and the decisions of the robot The Playstation 2 controller will be part of the wireless unit meant to handle the wireless function of the whole system The robot will also send out to the wireless unit vision related data and data pertaining to decisions made by the user The wireless unit consists of the Interpreter circuit two transceivers one on the mobile unit with the user the other on the robot the Playstation 2 controller and the LED display system It is depicted in the block diagram below The Interpreter circuitry is titled so because of one of its main task is to interpret the data coming sent out by the Playstation 2 controller through its cable The Interpreter circuit s 115 other task is to receive and process data transmitted by the robot and interpret them by displaying them accordingly through the LED display box The Interpreter is built around two microcontrollers that are independent of each other and do not communicate with each other directly i e there will be no direct data traffic between them even though they will be part of the same unit and so
2. Figure 5 Pin configuration of the AT90S2313 microcontroller Authorization to reprint obtained from Atmel refer to A 4 PIN 10 GND Ground pin PIN 20 VCC Supply voltage pin PIN 12 PIN 19 PORT B PBO PB7 Port B is an 8 bit bi directional I O port Port pins can provide internal pull up resistors selected for each bit PBO and PBlalso serve as the positive input AINO and the negative input AIN1 respectively of the on chip analog comparator The Port B output buffers can sink 20mA and can drive LED displays directly When pins PBO to PB7 are used as inputs and are externally pulled low they will source current if the internal pull up resistors are activated The Port B pins are tri stated when a reset condition becomes active even if the clock is not active Architecture Overview The AT90S2313 provides the following features 2K bytes of In System Programmable Flash 128 bytes EEPROM 128 bytes SRAM 15 general purpose I O lines 32 general purpose working registers flexible timer counters with compare modes internal and external interrupts a programmable serial UART programmable Watchdog Timer with internal oscillator an SPI serial port for Flash memory downloading and two software selectable power saving modes The on chip In System Programmable Flash allows the 29 program memory to be reprogrammed in system through an SPI serial interface or by a conventional nonvolatile memory programmer In System
3. X New Flowchart Open Option Syntax Simulate Program Eh eo m bas 15 symbol Blu al w5 Colour sensor blue content amp Variables 16 symbol GreVal w6 Colour sensor green content Set pin1 EZ symbol thldRed 150 Threshold for Red 52 pin6 18 symbol thldBlu 300 Threshold for Blue paa 19 symbol thldGre 275 Threshold for Green S3 pin 20 CSU pin2 2d Red Val 4 22 OUTPUTS SEN ne 23 symbol RedLED 7 The red LED is connected to output 7 i 24 symbol GreLED 6 The green LED is connected simulation GreVal w 25 symbol BluLED The blue LED is connected Constants F thldRed 28 Main program Je haere 29 Waits 5 seconds for bouncing effects to clear TXD Om ll ia 30 main _ RedLED 7 31 GreLED 32 ause 5000 5 second wait BAD t BluLED 33 do while Set 0 While Set is low decide which c RST Gam it Label 34 respective subroutine i aren 35 OV Ve main 36 If 52 0 and S3 0 then gosub sampRed sampRed 3g If S2 0 and 3 1 th b Bl SanpBlu 38 an then gosub sampBlu sampGre 40 if 52 1 and S3 1 then gosub sampGre blinkR 41 ao blinkB ic zn blinkG 44 45 LOOP AO Ge 0 46 goto main Al 4 gt 0 4 A si E 48 2 0 49 50 77 sampRED sample RED Subroutine gets red lic Generic 4j 0 Si samvRED Figure 67 Screenshot of Program testing Some pseudo code would be DO WHILE SET LOW IF S3 0 and S2
4. NENNE ENE ENNIENNI OCU OTUTU TUT M BESO RRR KKK KKK KALOZOZOZOLOLOLOLOLOLOZOCOLOLOLOLOLOLOZOCOZOZOLOE ERRIRIK o 2 3 4 5 6 7 Figure 3 Diagram of a single data byte Authorization for reprinting pending Figure 3 shows a typical diagram of the transmission of a data byte It can be observed that the DATA and the COMMAND lines can transmit data at the same time meaning that the controller cable is two way traffic for data The shaded areas represent whatever data is being transmitted The ATT line is held low by the Playstation console or the interpreter to allow the data on the COMMAND line to be received by the controller The ACK line is pulled low for a short time after the transfer of the data byte Data Frame Format The Sony Playstation 2 DualShock 2 will be used for this project since it is the cheapest and its design is the simplest available one today facilitating the design process for an interface circuit When the Playstation 2 console or the interpreter initiates communication with the controller it sends out the first byte 0x01 through PIN 2 COMMAND PIN to the controller in order to startup the process In response the controller sends out its model number which is 0x73 for the one that will be used in this project through PIN 1 DATA PIN As the controller transmits its model number the console simultaneously sends out through PIN 2 a second byte 0x42 which means Request for data T
5. which is ideal for very low power applications Nickel Metal Hydride NiMH has a nominal output voltage of 1 25 Volts and can provide 1300 to 2500 mAh in AA size It provides a lower power to weight ratio than other technologies but provides a medium life cycle of 300 to 500 times It has low toxicity but should be recycled Nickel Cadmium The nickel cadmium battery is a popular type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes The principal advantages of NiCad over 64 other rechargeable types is lower weight for a given quantity of stored energy good charging efficiency small variation in terminal voltage during discharge low internal resistance and non critical charging conditions They can be used in place of regular batteries in most applications and they are more difficult to damage than other batteries tolerating deep discharge for long periods The disadvantages of the NiCad rechargeable batteries include its higher cost They require extra labor to manufacture and thus are typically more costly than other battery types They also exhibit a very marked negative temperature coefficient i e as the cell temperature rose the internal resistance fell NiCad batteries also exhibit thermal runaway where the charging current would continue to rise until the battery destroys itself Due to all these disadvantages the nickel cadmium technology is falling out of favor Nickel Cadm
6. However even with limited knowledge regarding the mechanical system several drive specifications were made since the mechanical system is at least bounded by its own set of specifications Although the Drive subsystem stands to be fairly complicated its high level specifications aren t Specifying the clearing rate or roughly how tall of an object can the robot step over the robot s walking speed and the quickness of its response to input provide a fairly comprehensive high level specification of the robot s behavior The robot should be able to clear or scale at least 15 cm move at an average velocity of 5 m s and respond to commands or be able to alter its direction within 100 milliseconds If the drive system is able to adhere to these specifications then a fairly realistic gait should be exhibited by the hexapod robot 13 3 3 Vision Detailed specifications about the different components of the vision system are included here The main objectives of the vision system are to detect three separate colors 3 3 1 Color Sensor The image sensor is the gateway to the outside environment The color sensor must be able to detect color A huge color range is not needed since only three colors will be selectable by the user red green or blue Different hues of these colors do exist so an 8 bit color range seems very reasonable that is if a digital solution is to be implemented If it is a digital solution an analog video camera
7. Programmable Flash The AT90S2313 contains 2K bytes on chip In System Programmable Flash memory for program storage Since all instructions are 16 or 32 bit words the Flash is organized as 1K x 16 The Flash memory has an endurance of at least 1000 write erase cycles The AT90S2313 Program Counter PC is 10 bits wide thus addressing the 1024 program memory addresses EEPROM The AT90S2313 contains 128 bytes of EEPROM data memory It is organized as a separate data space in which single bytes can be read and written The EEPROM has an endurance of at least 100 000 write erase cycles The EEPROM access registers are accessible in the I O space The write access time is in the range of 2 5 4ms depending on the VCC voltages A self timing function however lets the user software detect when the next byte can be written When the EEPROM is read or written the CPU is halted for two clock cycles before the next instruction is executed UART The AT90S2313 features a full duplex separate receive and transmit registers Universal Asynchronous Receiver and Transmitter UART The main features are e Baud rate generator that can generate a large number of baud rates bps e High baud rates at low XTAL frequencies e 8 or 9 bits data e Noise filtering e Overrun detection e Framing Error detection e False Start Bit detection e Three separate interrupts on TX Complete TX Data Register Empty and RX Complete Data transmission is initiat
8. a a aches BE Sa ate 15 3 4 2 The Xbee OEM RF Module Transceiver cceceessccscecececeeeessneceseceesenenns 19 3 4 3 BasicMicro s Atom Pro 28 M ssssssssssssssssssesssesressssersssseresssererssesressssressssreesss 20 BD POW CE AEAEE PEE T E ETE PEE E EEEE sabe sel AET E E A BA 32 35 1 Power Supply System esinsin ne aa a a ii 32 Section 4 Research and Investigation esssesssseeesssessessseseseessstesstesseeeseresseessseesseesseessee 34 4T Mechanics sont E a A a SOA EA ae oP N 35 AVA Body Chassis yiscee vsisisigesieioasaieals deaciatesvaasisessaesdenasadaa e aaraa N E ar aiei 35 4 12 Vision Unit CHASSI Synni an a a a aeiia 39 ATES DIOS ANG MOTI G52 oirn E E T E E EE E EE 40 AD om D i E E S ENEE E A EA EEEE E EE T 45 AESAAT OT EEE E E E A E E E E A E ea id 49 4 4 Wireless Communicati ee h aR a TE Ra SOT 61 AR ONU A BELAIT AAEE EAE E EE IEEE AA EOE TE AEAT EE TEE TE EEEE ETETA 62 Sections STO Aei a a a ts ech Vea a a a de eee E 77 SME CHANICS 5 28 05 cshsr 5034 3 c5 5s saa Sbess a a Landes ated cats G Re ebeb ante sbenas 77 oA I E aT KS E r E E E E E A E E eee Sua es TE E 77 51 2 Leg Connections sonim eerie aTe o E E E AIKE E A EEES e SS 77 De MIDTIN GR EET AEDEP PAA AE ETEA E TEE E AS E E TE A TE EREE AA 78 SO MIIO e alas Pe E EE E E A A boob E E Hao 81 5 4 Witel ss Comm nicatiO Nns eanan a N A O S ONN R 85 54 1 The Controller Interpreter 1 33 03 ccicaajcia ainsi assis cices aliens 87 D4 De Phe EFANSCOLVELS
9. a battery as its main power source All batteries in general only produce a single voltage level while the robot s subsystems require a diversity of voltage levels in order to function properly Therefore the power supply system must be designed to provide all the subsystems with the necessary power that they require Given that the main power supply of the robot is battery it consists of a combination of DC to DC converters using linear or switching regulators which help regulate the different voltage level that each subsystem requires For efficiency need and our budget design considerations is taken into account in choosing the voltage regulators Since the battery also powers the servos and motors which can cause noise therefore filtering and voltage isolation is advantageous for the robot s computer system The robot s power system design is influenced by the different power requirement of its subsystems Given that the power is a DC voltage source that only provides a constant voltage while the subsystem require different voltage levels in order to operate Therefore voltage regulators are used to convert the high source voltage to lower voltages required by the different subsystems A voltage regulator is device that accepts a DC input voltage and produces a DC output voltage In general the output voltage is at a different voltage level than the input voltage The input voltage may be lower or higher than the output voltage depending
10. and when to do it Ina few decades from now robots will probably be as commonplace as seeing someone led by a seeing eye dog on the streets The robot we are building is intended to be a remotely controlled spy robot with some of its functions being controlled thru an RF joystick controller It is going to be more or less shaped like a spider with six legs and a field of vision The purpose of the robot is to be able seek and distinguish between objects of certain colors that are going to be programmed in its memory In order to do that the robot will have vision unit that is compose of a color sensor that is going to be housed underneath the robot s body to a a color sensor unit and circuit will look for certain colors while it is walking once the targeted object is found and LED of that colored object will illuminate indicating the found target A microcontroller will coordinate the robot s movements and direction Another microcontroller will decide if the color being detected is the one selected by the user The robot will have a DC voltage source as its main power source Section 1 Introduction 1 1 Motivation and Rationale The motivation of the group for this project was to gain practical experience in design and prototyping while putting what has been learned in our undergraduate classes to use Although the group originally wanted to produce something of utility that could fill some type of need the group realized that the exper
11. apparent solution that one was looking for is found 4 1 3 2 Leg Pair Packages Although suitable joints were found on the same site their use would have required a bit of modification to the legs and to our original design In essence they would be brackets enabling the legs to rotate and giving space to mount the motors onto the design Due to the extra difficulty an email was sent to LynxMotion prior to ordering explaining the scope of the problem and if they knew of any solutions Much to our surprise there was another solution The solution had eluded us in the past since the product was fairly difficult to find while navigating LynxMotion s website Ironically by shopping other third party vendors such as www active robots com one could reach the product sooner The solution was to buy a leg with three degrees of freedom already incorporated in essence buying the legs and the joints together Logically this would cost more money 42 Since the solution was appealing but more expensive further research was done prior to accepting it By comparing superficially the cost of a 3 DOF leg pair with joints and what it would cost to buy the proper joints and the legs separately the team realized that no significant savings would be made in money if building the legs separately was chosen Compounding this fact with the fact that the team would still have to do further research in order to understand how to actually put the leg an
12. budget may change accordingly to meet the needs and requirements of the project Table 6 below show the necessary components needed and their price in order to achieve a working prototype Table 20 shows a preliminary cost for the project it may be lower or higher depending on parts and components costs 120 Components Price Quantity Total Budget Servos 107 97 18 323 82 Basic Atom Pro 28 60 00 1 60 00 Microcontroller Xbee Module Adapter 10 00 2 20 00 Xbee Module 20 00 2 40 00 Color Sensors 45 00 1 45 00 LM317T 48 10 4 8 Batteries 22 95 2 45 90 Chassis 39 95 12 39 95 Playstation 2 15 1 15 Controller Charger 1 ServocontrollerServos 47 09 1 47 09 speed controller Legs 33 219 05 Microcontroller 7 95 1 20 PICAXE Color 44 95 1 39 99 Sensor TOTAL as of 534 33 12 8 08 Table 20 Number of components and their prices 9 2 Safety Tips 1 Over time alkaline batteries are prone to leaking potassium hydroxide which is a caustic agent that can cause respiratory eye and skin irritation This can be avoided by not mixing different battery types in the device store the battery in a dry place and removing the battery when the device is in storage And also to reduce any hazards proper disposal of the battery is recommended 2 Lithium ion batteries can rupture ignite or even explodes when expose to high temperature environments theref
13. creating a project with strong learning potential was the primary concern Section 2 Definitions It is sometimes said that within every problem there s a smaller problem just screaming to get out In order to facilitate research design construction and testing the overall project problem was decomposed into several sub problems We will refer to these sub problems as subsystems Each subsystem was then further decomposed into several other sub problems which we will refer to as the subsystem requirements To better put this into perspective each requirement will be explained in relation to its goal or objective to the project as a whole The purpose of this section is to identify project subsystems and their respective goals and objectives The remaining sections will present the research design implementation and evaluation of these same objectives making these definitions an essential conceptual piece of the puzzle 2 1 Goals and Objectives Below is a succinct recap of project scope and overall objectives in order to motivate the decomposition into subsystems A hexapod robot is to be designed and built such that each leg provides three degrees of freedom and the robot itself is able to move independently in 8 distinct directions or along two axes of motion Mounted on its chassis will be an autonomously scouting camera capable of distinguishing between 3 colors and communicating to the user when it has found an object of th
14. cycle 100 s time 100 s time 100 s time 50 to 500 Accucell Special No Yes Yes No Disposal needs Self Discharge Fast Moderate Very Slow Slow 30 Month 10 Month Memory Effect No Yes No No Price for 2 5 00 5 49 Standard 6 99 3 60 AA s 6 99 Hi Cap Table 16 Comparison of the different rechargeable battery types Wall outlet Since batteries are never at a constant voltage and with the fact that our robot may consume a good amount of power for example we are going to use 18 servo motors to move the legs of the robot and each servo need 4 6V to 6V and can draw between 150 mAh tol80 mAh so their power consumption alone would be between 69W to 1 08W each Therefore as one of my options to power the robot as a last resort just in case the battery we may need may be too expensive for our budget connecting the robot to an external voltage source such as a wall outlet is included Or instead of using the same power source for both our control circuitry and our servos and motors the robot may use a battery for the control circuitry and use the wall out outlet to power the servomotors of the robot which would cost us less money 66 Voltage Regulators Given that the different components of the robot requires different amount of voltages and to avoid voltage fluctuation voltage regulators are used to output a constant amount of voltage to the different subsystems of the robot There are two major types of vo
15. decisions concerning targeting To one s comfort the Playstation 2 controller provides two analog joysticks a control pad the cross looking buttons and twelve buttons including the ones that are pressed by pushing down on the joysticks but not including the Analog button The left hand joystick which is a two axis joystick is to control the motion of the robot that is the movements of the legs corresponding to such motion as it usually does for the controlled character in several Playstation 2 games The right hand joystick which usually controls the sight of the video game characters the joystick buttons and the control pad will not be used For the joysticks to be operational the controller has to be set on Analog mode done so either by pressing on the Analog button or by the software or video game which activates it automatically due mostly to the nature of the game games that require solely the use of the analog sticks such as flight simulators and such When the controller is set on Analog mode the red LED located just below the Analog button is lit For simplicity the circuit that will emulate the Playstation or the controller interpreter will be programmed to set the controller automatically on Analog mode 15 The R1 and L1 buttons will be assigned the tasks of Kill and Unlock respectively while the rest will select the colors of the objects
16. each leg In order to facilitate design the specification on legs will be that each individual leg can support at least two pounds Thus although there is some uncertainty in exactly how much weight the legs must withstand until the chassis is obtained and connection points are decided upon the legs should be more than capable of withstanding any load distribution given by the maximum five pound chassis Although the joints discussed in the next section will make sure that the twisting and shearing forces on the legs are not very severe legs obtained must also be sufficiently rugged to withstand twisting or internal forces Therefore another specification on the legs is that they must be sturdy throughout and not be weak on any particular bend or juncture The entire leg when fully stretched should not measure more than a foot If the legs are too long then not only will it be more difficult to move them but the body forces on them will be more severe Also since the body chassis will be more than 3 feet at its longest point and be relatively light having legs in excess of a foot would increase the robot s center of gravity too much and would compromise design and eventual performance Three joints will compose the leg the knee joint and two hip joints Although the joints will be discussed in greater detail in the next section they are introduced now since they provide a natural way to measure the distribution of length in each leg The len
17. either the current or the temperature of the battery goes too high Modern nickel metal hydride batteries contain catalysts that immediately deal with the gases that develop as a result of over charging without being harmed However this only works with over charging currents that are C 10 h nominal capacity divided by 10 hours As a result of this reaction the battery will heat up considerably which will end the charging process Nickel Metal Hydride batteries are considered to commonly have lower environmental impact than nickel cadmium due to the absence of cadmium which is a toxic material however proper disposal is advised 122 Appendix A Reprint Permissions A 1 CrustCrawler Products Permission Regarding pictures on your website 17box x r Roberto Miguez to webmaster show details Nov 23 2 days ago Reply Dear Webmaster For our Senior Design Project at the University of Central Florida we might be using some of your products Since we are building a hexapod robot many of your products are exactly what we need Our documentation needs us to show where we obtained our products from Would it be alright if we use some of the pictures on your website to better explain the products A picture really is worth a thousand words The immediate caption below the picture would mention your company and there would also be mention of the company and website at the end of our documentation All we want to do is take the e
18. in the gaming field The ATR2406 stood out as it operates at 2 4 GHz in the ISM band and wireless gaming is one of its main applications The only drawback though is that a circuit has to be built around it with care due to the high operating frequency Moreover an antenna is needed and a feeding line is necessary The feeding line has to be designed and carefully drawn on the board with the right dimensions so that it matches the impedance of the antenna to that of the output pin of the ATR2406 chip Development boards built around the ATR2406 are available though They are pre built circuit boards containing the chip equipped with a jack or a connector where to connect a whip antenna is also provided 61 But its cost turns out to be a hundred times that of the chip itself So another option was pursued Google was used in tracking down more compatible transceivers It led to Texas Instruments Website where the CC2500 was considered But similar problems arose as only the chip is provided Similarly development boards were available but were also too pricey for the budget Then Digikey results filter was used to find more appropriate transceivers for the project Out of all the transceivers Digikey sells the parameters were set Gaming Devices for Applications and Integral Antenna It spat out transceiver models from AeroComm like the AC4486 and the AC4424 The AC4486 operates at 868 MHz and the AC4424 operates at 2 4 GHz Bo
19. microcontroller will be collected by the transmitting transceiver transmitted to the receiving transceiver that would be on the Interpreter s circuit To verify the data received by the transceiver a serial in parallel out shift register will be used to convert the serial data output from the receiver to parallel format which will then be displayed by LEDs The process is depicted in figure 65 below Robot Transceiver Transceiver Serial In Parallel Out Shift Register 8 bit LED Display Cicuit T EDn Fn Figure 65 Block diagram of the test setup of the robot and the transceivers 107 The transceivers and the PIC1I8F458 MCU The information from the robot to the Interpreter would be contained in an 8 bit long word The transceiver on the Interpreter will receive it from the transceiver on the robot and transmit it to the PIC18F458 MCU which will process it and output the appropriate word that will display properly through the LED Display Figure 66 shows a block diagram of this experiment is shown below gt A Word Generator Transceiver Transceiver Serial In Parallel Out Shift Register C ooo 4 8 bit LED Display Cicuit PIC18F458 MCU E 6 610 6 6 hh 0 Block 66 diagram of the test setup of the transceivers and the PIC18F458 MCU 7 6 Wireless Communication and D
20. of current they cause large voltage distortions These distortions affect the electronic components therefore having a separate power supply for the motors is better and more efficient for the robot The second block will consist mainly of the electronic devices and components that form the electronic circuitry and control of the robot These components in general draw small amounts of currents and are very sensitive to voltage distortions the power supply uses voltage regulators to deliver exactly the voltage and current required by these electronics so the subsystems can efficiently operate Below figure 41 and 42 show block diagrams of the two different blocks SERVO MOTOR 18 6v LINE VOLTAGE COMMON VREG Figure 41 Power supply block diagram for servo motors 92 5V LINE VREG Microcontroller VOLTAGE COMMON 0 1 LINE VREG Color sensorCamera VOLTAGE Re i V1 COMMON 10V 0 0 Figure 42 Power supply block diagram for the electronics subsystems Section 6 Building Prototype This section is concerned with providing the details necessary to physically assemble the robot The integration of certain subsystems will be shown and how they will come together in order to produce the final product Since the robot has not been built yet the pictures and figures used do not always represent the team s robot However the images are cl
21. the microcontroller and sensors and those that do not require a precise voltage such as the servos and motors etc This makes sure that the microcontrollers of the robot are not affected by the supply changes due to current surges in the servos and motors Robot Power Source The electrical noise analysis suggests the need for a power supply that is designed to reduce or eliminate noise interference between subsystems As a result the robot adopts the isolation configuration as a valid solution to the noise interference problems between subsystems The primary voltage source for our robot is a DC battery voltage source The main power is distributed to all the subsystems according to their respective voltage 91 current and power requirements Since the power requirements for each subsystem varies because subsystem requires a different voltage Since interferences between each subsystem is also an issue to consider in the power supply design the subsystems are devided into two different blocks One block has a huge current draw and causes large voltage distortion such as the servos subsystems and the other block has a lesser current draw and does not tolerate voltage distortion such the microcontrollers subsystem The first block consists mainly of the servos which drive the legs of the robot As seen from Table 1 the robot uses 18 servo motors to move the robot Therefore most of the power is consumed by the servos and since they draw a lot
22. the rotations into a meaningful sequence to effect linear motion but it might not do so very elegantly Thus although it can be resorted to if things do not work as planned a more elegant solution will be pursued by analytical means 48 4 2 2 2 Inverse Kinematics The scope of inverse kinematics is determining the position of certain joints in a flexible object in order to obtain a certain movement or pose Basically the technique would require analytically determining what the rotation of the two hip joints and the knee joint do to the leg position of the robot By developing an inverse kinematic model of all six legs and understanding how to properly manipulate the joints in order to create linear motion the drive system can be completed Inverse kinematics will be used to program the servomotor controller board with a proper gait algorithm Although the technique might prove to be mathematically complex it should not involve mathematical analysis outside of the realm of advanced trigonometry 4 3 Vision 4 3 1 Camera Image Sensor There are a wide range of options of cameras for robotics applications and projects Usually the important requirements being image resolution and frames per second and depending on the application the designer chooses accordingly Cameras for robotics can be a consumer grade webcam with a USB or Firewire connection or a stripped down version of these plainly known as CMOS image sensors CMOS ima
23. voltage is at a different voltage level than the input voltage The input voltage may be lower or higher than the output voltage depending on what it is used for When the input voltage is higher than the output voltage the regulator is referred to as a step down voltage regulator And accordingly when the input voltage is lower than the output voltage the regulator is referred to as a step up voltage regulator For our robot the source voltage will generally be higher than the required voltage of the different subsystems therefore the power supply implements the use of step down voltage regulators Regulators in general are used for the most part in electronic devices and circuits These devices most of the time contain sub circuits and subsystems where each of them require a different voltage level that is different from the voltage source supplied by the battery The voltage required by these subsystems and sub circuit can sometimes be higher or lower than the battery source voltage and possible be a negative voltage and it drains the stored voltage in the battery therefore the source voltage of the battery will decrease DC to DC regulators allow us to generate multiple different controlled voltages from a single battery source voltage As a result it saves on space and complexity of using a number of batteries to supply every individual part or sub circuit of the robot DC to DC voltage regulators are widely divided into linear voltage both type
24. 0 THEN GO SAMPLE RED SAMPLE RED COUNT PULSES ON INPUT 1 for 50 MS STORE NUMBER IN WORD4 IF WORD4 gt REDTHRESHOLD BLINK REDLED IF WORD4 lt REDTHRESHOLD GO TO SAMPLE RED This code is very simple in structure and easy to test 7 5 Wireless Communication Before the interpreter is put together a test of the program in the microcontrollers is necessary First the interaction between the AT90S2313 MCU and the Playstation 2 controller is to be tested before everything else The testing of the interaction between the transceivers and the AT90S2313 is to be done in order to make sure that data traffic will be flowing smoothly between from the Interpreter circuit to the robot Then the communication between the PIC18F458 MCU and the transceivers has to be looked into to ensure the correct data flow from the robot to the interpreter And finally the testing between the link between the LED Display box and the PIC18F458 MCU will be done 105 The AT9082313 Microcontroller and the Playstation 2 Controller One port of the AT90S2313 microcontroller will be used to collect the data from and interact with the Playstation 2 controller The data from the Playstation 2 controller is in 8 bit serial format The microcontroller will organize the data and use another port to output the control data to serial in parallel out shift register that will in turn output the data in a parallel 8 bit format just for the testing To check if the output m
25. C bracket Figure 53 Horizontal hip motor connection from www LynxMotion com reprinted w permission Do the same procedure for the second servo and again make sure to route the wire as shown These motors will provide hip joint motion in both the vertical and horizontal planes they are the final two degrees of freedom needed to build the design Figure 54 illustrates the connection of the second servomotor 98 Figure 54 Vertical hip motor connection from www LynxMotion com reprinted w permission 6 1 1 3 Knee to Hip Connections Now the entire leg will be connected Attach the servo to the C bracket using the 2 tapping screws and the Figure 55 Make sure that the servo is centered before attaching to the C bracket Make sure that the leg is properly aligned that is that the knee and hip joints are all relatively orthogonal to maximize range of motion as specified in the specification and design sections Zz Figure 55 Joint integration from www LynxMotion com reprinted w permission Finally attach the C bracket to the servo hinge as shown Refer to Figure 55 for illustration of the connection and Figure 56 for an illustration of the connectors Make sure to route the servo wire as shown Leave enough slack for the leg to be able to freely move without pulling on the servo wire 99 Figure 56 C bracket connection to leg from www LynxMotion com reprinted w permission This concludes the p
26. Pair from www LynxMotion com reprinted w permission This leg package was implied to not be as rugged as the previous one by its description However its price was 18 25 cheaper at 69 65 Since 3 leg pairs were going to be bought if this pair was chosen over the other pair it would amount to a savings of 54 75 which nearly amounts to the price of another leg pair Based on price alone this seemed like a better buy but the curved aesthetics of the leg also made it convincing When analyzing the specs of this package e Hip Hor to Hip Vert 29mm e Hip Vert to Knee Vert Femur 57mm e Knee to Foot Tibia 141mm It was noted that although the first and last leg portions differed by a significant amount the total leg length in both packages differed only by 8mms where this package was longer This made sense since the curved knee to foot portion would need to be a bit 44 longer in order to support the same amount of weight that the straight version could Since the leg pair was significantly less expensive was more aesthetically appealing and met necessary specifications three of these leg pairs were ordered The fact that these pairs were not as rugged as the previous ones were discussed with LynxMotion staff and they mentioned that the difference was minute and that the leg pairs should have no problem meeting the team s specifications 4 2 Drive The research for the drive subsystem involves identifying both ha
27. Table of Contents IXECUU VESUMIINALY serani iane e aa oneconcadaceus a OS 3 Section 1s MtrOAUCtHOM sas e A e a Coss sat A A AA EEE EA Gees EESE Denes EERS 4 ti Motyvatonand Rationale enian ite a a saves aT 4 SeCtHOn 2 DIA DOTTO EEA yes oes os eas ess aise ae eae See aot E E TE 4 2i Goa lsand ObJECU YC Sis Fails dasha ale ii iost aE ada Mula ee in Rr aa iN ei A al 5 2TA Mechanic Sir ennnen anaa a EA baat E EO 5 PAI P28 D jd AY o E ET A E E or A E een E ee en ee TA 6 DVS Vispaa namaa n a ad bea a a cea Ss Dest he ed Base ES 7 2 1 4 Wireless Communication 0 ccccccceceesesscececcceceesesseaecececeeseeenenseceeeeeeeesenenteaeees 8 2 VO P OWL soln Sescnent a eek Oued te snes tel lies a a is a e a AISI 9 Section 3 SPECIM CATIONS viv s ssieiacapeacieussdeasssanbaneneagodeda a e a KE EE EE Eai 10 Sal MISCHANICS si ac EEE EE E A E E E ET 10 he Fed Ga Ehassi Senn ee a 10 Del DL Os ss icasicades tune E EEE A EE 11 aad Fs ALOT IE A E E E Ee eee 12 DED DIVE h o i EE E E sa E EREA E ie Bi E PL GS E ERE i E EREN 13 MASI OM 55255 a a a N aa a a e a A O NE 14 Jl COIS od 0 ear ee eR Ce Ppa erry peer E eee 14 3 3 2 Color Image Processing is ssisstavsszescsaavsseadiss scaedaseavcdaasgveaderavaseedersdouedeonrateosneeees 14 BBs SiC ais sania E EE EEE don EE ease 14 3 3 4 Image Algorithms and Proces Sim wxs5j0s 2 ssesasncins dn sGass ddan cosa qalasncoinebv ce oraeesoned 15 3 4 Wireless Communication nsss n a E A A S an 15 JA The C OO E E a E
28. VDD pin 250 mA Input clamp current IIK VI lt 0 or VI gt VDD 20 mA Output clamp current IOK VO lt 0 or VO gt VDD 20 mA Maximum output current sunk by any I O pin 25 mA Maximum output current sourced by any I O pin 25 mA Maximum current sunk by all ports combined 200 mA Maximum current sourced by all ports combined 200 mA Table 7 Absolute Maximum Ratings of the PIC18F458 MCU Authorization to reprint obtained from Microchip refer to A 3 DC Characteristics TA 40 C to 85 C Symbol Parameter Condition Min Typ Max Units Vop Supply Voltage HS XT RC and LP 2 0 53 V Oscillator modes Vor RAM Data Retention 1 5 V Voltage V Por VDD Start Voltage for 0 05 V ms Power on Reset signal 25 Veor Brown out Reset Voltage 1 96 2 16 V BORV1 BORV0 11 2 64 2 92 V BORV1 BORV0 11 4 07 4 59 V BORV1 BORV0 11 4 36 4 92 V BORV1 BORV0 11 Ipp Supply Current XT Oscillator Configuration FOSC 4 MHz VDD 2 0V 25 C 0 7 2 mA VDD 2 0V 40 C to 85 C 0 7 2 mA VDD 4 2V 40 C to 85 C 1 7 4 mA RC oscillator configuration VDD 2 0V 25 C 1 2 5 mA VDD 2 0V 40 C to 85 C 1 2 5 mA VDD 4 2V 40 C to 85 C 2 5 5 mA RCIO oscillator configuration VDD 2 0V 25 C 0 7 2 5 mA VDD 2 0V 40 C to 85 C 0 7 2 5 mA VDD 4 2V 40 C to 85 C 1 8 4 mA Table 8 The DC Characteristics of the PIC18F458 MCU Authorizati
29. a doing a Senior Design project I purchased the CM 26N Camera Module from your website and like to use the data sheet as well as the images of the camera module from your website Your company will be given credit for the data sheet and images in our documentation Thank you for your time Sincerely Steven Schultz 127 A 7 CMOS Image Sensor Figure 17 From steven_schultz hotmail com Show Cc amp Bcc Emote To ousama gmail com Click the To button to see your contact list x Subject image persmission for senior design project Verdana i 10v BT Hi research I encountered your drawing of the CMOS image sensor with lens assembly I would like permission to use it in our documentation you would be given credit for it Thanks Steven Schultz A 8 CMOS Image Sensor Figure 18 Name Steven Schultz Email steven_schultz hotma Subject Samsung CMOS image Message Hi a I m an Electrical Engineering major at University of Central Florida working on my senior design project across the pictures on your site while doing research ing ixel I am asking your permission to use this photo in my documentation If you could please send a reply back Submit 128 A 9 Texas Instruments TVP5150 Approval Analog amp Mixed Signal Email Semiconductor Technical Support Thank you for your interest in Texas Instruments Semiconductor products and services To assist us
30. a transistor as a switch that alternately connects and disconnects the input voltage to an inductor This alternate switching that connects and disconnects the input voltage to the inductor forms two operating modes for the converter The lower diagrams show the current flow paths for each of the modes when the switch is ON and when the switch is OFF When the switch is turned ON i e Mode 1 the input voltage is connected to the inductor as the switch completes the circuit The difference between the input and output voltages is then forced across the inductor causing current through the inductor to increase hence charging the capacitor When the switch is turned OFF i e Mode 2 the input voltage applied to the inductor is removed However the voltage across the inductor will adjust to hold the current constant since the current in an 71 inductor cannot change instantly During this time the capacitor discharges into the load contributing to the total current being supplied to the load Figure 28 below shows the diagrams of a buck converter SWITCH Figure 28 Diagram of a Buck Converter Reprint permission granted through site www national com Buck Boost Converter The Buck Boost converter is otherwise called the inverting converter It produces an output voltage that is opposite in polarity to the input voltage The magnitude of the output voltage can be greater than or less than the magnitude of the input voltage Therefo
31. ach step will occur a given value 6 after the previous step That is the time step will be uniform across all steps So if the walking sequence consists of 6 steps then the first step will occur and then the second step will occur afterwards The value 6 is in units of time such as milliseconds For the purpose of analysis 5 will be equal to zero 0 instantaneously after a step and will be negative before it Thus if it is necessary to begin a step before another step is finished then will assume a negative value It seems to be a reasonable assumption to make right now that the time constant between steps whether it be negative zero or positive can stand to be uniform across all steps This fact may be altered of course as building progresses In order to further reduce complexity the same linear motion algorithm will be used in order to advance the robot in any direction Due to the fact that the robot has a circular chassis and that the legs will be connected with even spacing the robot will be rotationally invariant Therefore as long as the axes of linear movement are all equiangular the same sequence of steps can be used to cause linear movement regardless of the direction given to the robot from the radio controller Of course if a command is given to the robot in the middle of its sequence the walking algorithm must be able to either immediately reset to the beginning standard position or be able to transition smooth
32. along with a video decoder would be used This 8 bit range will allow for 256 total colors to be seen by the robot Digitzation of the signal will allow for much easier interfacing with the video processing unit an FPGA or microcontroller for example The image sensor must also be as small and lightweight as possible to lessen the burden on the chassis and legs of the robot The robot will be controlled by the user via a remote control The image sensor must scan the environment in order to save the user from re positioning the robot Therefore the angle of the lens must be taken into account The lens angle will be as close to 90 degrees as possible as to minimize the movement needed for continuously scanning the environment The frame rate of the image sensor is not a strong constraint because the robot will not be moving so fast that the processing cannot keep up A frame rate of at least 2 frames per second will suffice for this project 3 3 2 Color Image Processing 3 3 3 Speed Since our robot is not expected to go very fast color and image processing does not have to be extraordinarily quick Our robot is expected to walk about 0 25 meters second The objects detected by our robot will be stationary and solid colored thus simplifying the process 14 3 3 4 Image Algorithms and Processing To detect an object of a certain color our image processor must be able to detect boundaries or edges Then it must determine how t
33. and Image Processing Algorithms In this section algorithms and processes will be discussed for two kinds of implementations the camera implementation and the light to frequency generator implementation There would be no need for an image processing unit such as a microcontroller or FPGA for the photoresistor or phototransistor circuit Once the image is captured and digitized it is sent to the FPGA where it will be processed An FPGA represents programmable logic gates and more or less has the same role as a microprocessor or more specifically a digital signal processor Digital signal processors DSP are highly specialized components with many of them today containing many high end embedded applications on a single integrated circuit chip Digital signal processors store an image in memory fetch it do mathematical operations and then store it again in memory Needless to say this becomes very time consuming especially for larger resolutions Even though processors can achieve frequencies in the Giga Hertz range it is the inherent nature of image processing calculations that cause DSPs to be relatively slow creating a bottleneck The mathematics of image processing makes FPGAs very attractive for algorithm realization and implementation For instance image convolution a window of pixels is treated with a mask where individual locations in the window are weighted according to a set of previously defined coefficients For each posit
34. and datasheets The immediate caption below the picture will mention your company and website and there would also be mention of your company at the end of our documentation Please know that we will not make any monetary gains or other profits from this The only purpose behind our project is to enable us to be evaluated academically by our academic coordinator 4 simple email response to this will be enough Thank you very much in advance hillipe Jean Jumeau lectrical Engineering B S E E Undergraduate University of Central Florida 126 A 5 Mathworks Permission From steven_schultz hotmail com Show Cc amp Bcc Onecare To steven_schultz hotmail com Click the To button to see your contact lis Subject Image use for Senior Design Project A Verdana vi 10v 8B F UY Hi I am an Electrical Engineering student at University of Central Florida working on a Senior Design Project We will be using image processing and acquisition toolboxes for testing and simulating our project I am asking your persm from our documentation Thanks for your time Sincerely Steven Schultz A 6 Spark Fun Electronics Permission From steven_schultz hotmail com Show Cc amp Bec Qe ees To spark sparkfun com Click the To button to see your contact list x Subject Images for Senior Design 2 ifi A Verdana v 10 y rey Hi I am an Electrical Engineering student at the University of Central Florid
35. ant to spend the least amount of money possible on this project using rechargeable battery make the most economic sense The cost of buying the rechargeable battery and its charger may seem to be a lot at first But considering the fact that a lot of tests were done on the robot and during these tests the robot burned power which resulted in battery drainage and eventually the battery will not be able to provide enough voltage to satisfy the robot s power requirement For example since the robot has a battery source voltage that is 12V we can buy an eight pack of 1 5V AA batteries that 62 will cost us around five dollars at a convenient store since these batteries are not rechargeable we would have to keep buying these packs as we are performing tests on the robot which will end up costing us more money on the long run But buying a rechargeable battery and a charger which may cost around 50 saves us money in the long run because the battery can be recharge whenever it cannot supply the desired voltage for the robot to function properly Lithium ion Batteries Lithium ion batteries are a type of rechargeable battery commonly used in consumer electronics They are currently one of the most popular types of battery for portable electronics with one of the best energy to weight ratios no memory effect and a slow loss of charge when not in use They were first proposed in the 1960 s but first commercially released by Sony in 1991 Alt
36. at forms two different operating modes for the converter A functional diagram of the boost converter showing its two modes of operation is as shown in figure 27 below 70 Figure 27 Diagrams of a Boost Converter Reprint permission granted through site www national com The lower diagrams show the current flow paths for each of the modes when the switch is ON and when the switch is OFF When the switch is turned ON i e Mode 1 the input voltage is forced across the inductor which causes the current through it to increase With the Diode off the load circuit is isolated from the source circuit in mode 1 The capacitor is therefore not charging in this mode When the switch is turned OFF i e Mode 2 the decreasing inductor current forces the diode to be forward biased i e turned ON allowing the capacitor to charge up to a voltage that is higher than the input voltage Hence the voltage supplied to the load will be higher than the source voltage Buck Converter The Buck converter is basically used to reduce a DC voltage level to a lower DC voltage level It can therefore be referred to as a Step down Converter The voltage levels must also be of the same polarity Buck converters are essentially used in systems that use distributed power rails such as 24 volts to 48 volts which must be locally converted to smaller voltage levels such as 15 volts 12 volts and even 5 volts with very little power loss The buck converter operates by using
37. atches the buttons being pressed on the Playstation 2 controller 8 LEDs will be used An example of this testing circuit is depicted in figure 63 below AVR AT90S2313 Microcontroller a Playstation 2 Controller Port A Port B 8 bit LED Display Cicuit CPT Oe oO Figure 63 Block diagram of the test setup of the Playstation 2 Controller and the AT9082313 microcontroller The transceivers and the AT90S2313 Microcontroller To test the program in the transceivers the Playstation 2 controller data from the AT90S2313 microcontroller will be used The serial control data from the AT90S2313 will be collected by the transmitting transceiver transmitted to the receiving transceiver that would be on the robot To verify the data received by the transceiver a serial in parallel out shift register will be used to convert the serial data output from the receiver to parallel format which will then be displayed by LEDs The process is depicted in figure 64 below 106 J9 O4UODOIO1 NOW ELEZSOBLV Transceiver i Transceiver IX ab Serial In Parallel Out Shift Register db 8 bit LED Display Cicuit E S a a S Figure 64 Block diagram of the test setup of the AT90S2313 and the transceivers The transceivers and the robot s processing unit To test the transmission from the robot to the interpreter the serial data from the robot s
38. ate component selections and placement ensuring a proper and successful implementation of a DC power converter and printed circuit board implementation Specifications In the design of the power supply thus far we have specified that 1 The main voltage source of the robot are two DC Battery The source voltage is stepped down using regulators The power supply system accounts for noise issues and interferences Each subsystems have different voltage distortions Aaa arms Isolation is used to reduce the effects of noise and interferences between the subsystems e Voltage Regulators e 1 On Off Switch e Capacitors e 2 Batteries 33 e Resistors e 1LED Section 4 Research and Investigation A significant amount of research was necessary in order to properly design this project Given the scope of the project and the varied subfields of electrical and computer engineering that are involved the research and design components were divided amongst the members according to both their interests and skills This was also a natural split due to the strict schedule that must be adhered to in order to both design and build the project By having different members become experts in their given subsystem the team is best able to leverage skills while carefully balancing time Although the research component for each subsystem was done by individuals the same goal was had in mind throughout The parts or components to be obtained must satisfy t
39. atever the front leg does the back leg will do The only difference will be that some of the final movements will be mirrored or inversed or else one can imagine that one leg would try to move forward while the other 78 leg would try to move backward Therefore the same joint articulations will exist but they will all be mirrored Now since there will only in essence be three legs to worry about it seems natural to have a sequence of either 3 or 6 steps as a full sequence executing linear motion again with a time value of 6 which may be negative between each step for syncing purposes 5 2 2 2 Model Derivation In the previous subsection the analysis of the six legs was reduced to only three legs due to the properties of symmetry in movement a form of coupling the legs in order to reduce complexity Therefore only three legs need be analyzed in any direction By making the center of the directional heading on the middle of the three legs front legs which are coupled to the back legs to be analyzed there exists symmetry between the left and the right legs Therefore all that needs to be done is derive a model for the left or right leg to move mirror it on the opposing leg and derive a model for the front leg Thus the entire walking algorithm can be simplified to deriving suitable models for just a single front leg and a side leg Deriving a model for this type of situation is somewhat intuitive if one only considers the two legs a
40. ation of the legs The holes are also equally spaced as specified in the design Therefore once both the body and the legs are independently assembled they may be integrated by simply attaching the legs via the given tapped holes onto the chassis Once must make sure that the legs are all aligned and are perfectly orthogonal with the body chassis in order to provide maximum range of motion and the same range of motion for all legs relative to the body 6 2 Drive The major hardware component of the drive system is the collection of servomotors Their assembly has already been integrated into the assembly of the joints The servomotor controller board will then be inserted inside the body chassis as will all other electronics The gait algorithm itself will have already been uploaded onto the microcontroller in the servomotor controller board and requires no extra building 6 3 Vision The color sensor system requires little more than connecting wires to pins and mounting hardware on the chassis 6 3 1 Color Sensor The color sensor will be mounted to the bottom of the robot It will scan the area underneath for objects of certain color The output wire of the PICAXE Color sensor will be connected to pin 1 of the microcontroller 6 3 2 Microcontroller The microcontroller will be soldered onto a printed circuit board along with the indicator LEDs and switches 101 Section 7 Test Various tests will be conducted to ensure that t
41. ay communication or data transfer between the controller and the interpreter one of the transceivers and the interpreter of course between the transceivers then between the second transceiver and the robot 85 Data Ack Playstation 2 Controller Interpreter Playstation 2 DualShock 2 Controller Command Clock Att Vision Data Controller Data Transceiver 1 Controller Data Transceiver 2 Robot Vision Data Figure 39 Block diagram of the wireless system Playstation 2 Controller and Playstation 2 Controller Interpreter As explained in details above in Section 3 4 1 the Playstation 2 controller will be communicating with the Interpreter circuit the latter emulating an actual Playstation 2 console The interpreter circuit will supply the necessary voltage the command data and the clock signal to the controller whilst the latter will send the data essential for the control of the robot Playstation 2 Interpreter and Transceivers In addition to communicating with the controller the Interpreter circuit will also transmit and receive data from the transceiver After processing the data from the controller it will transmit the data to the robot s central unit though Transceivers 1 and 2 Moreover it will receive through the Transceivers the vision related data from the image processing unit of the robot and process them and turn on th
42. buffer The buffer would be useful for comparing the current frame with the last for instance a ATMega644 PICAXEt8x Memory Size 64 KB of About 1000 program lines of memory 4 kB program code SRAM 2 kB EEPROM Power 240 micro 150 micro Consumption Amp 1 MHz Amp 1 MHz 3 V 2 4 5 V Table 16 Comparison of Considered Microcontrollers We considered the ATMega644 and the PICAXE family of microcontrollers The PICAXE18X in particular was a good balance of features and usability in the PICAXE line These microcontrollers are readily available and have excellent documentation They are also relatively inexpensive usually less than 20 small in size and very low in power consumption 60 4 4 Wireless Communication The Controller The original plan was to use a joystick the kind used in playing flights simulators But all of the joysticks on today s use USB connectors and ports To extract and interpret the data for the central unit of the robot a USB converter circuit would be necessary this would turn out to be an unnecessarily tedious process and require some extra months So to avoid such situation the Playstation 2 DualShock 2 controller was chosen for the project Using some documentation on the Playstation 1 controller found on the Internet the data can easily be extracted directly from the 9 pin connector and interpreted with a microcontroller circuitry with which the controller will in
43. cceceeesssaeeeeeseeeeneneas 123 A 2 Lynx Motion Products Permniss1 On 4 3 soss35 cascens tags ses scasvacastass ooss aaeesnsusdvacvvatdeqeastas 124 A 3 Microchip PE TINTS SUT enasi aston tale hee vi e are a 125 A 4 Atmel Corporation Permission ccccsccccssececssceesseceessccecssccecnsececssccesssceeeaeens 126 A SMathworks Permissions Gronin na acobnades is ay ri Ochoa eas teat araaer 128 A 6 Spark Fon Electronics Permission vos besos nt oe gdntisatacees sets avieeigiaxceseisn 129 A 7 CMOS Image Sensor Fig 17 Permission cccceeeeceeeeeneeeeeeaeenes 129 A 8 CMOS Image Sensor Fig 18 Permission 0 ccecceeeeecee neces eens enees 130 AD Texas Instruments TV P5150 Permission i secscscssderswiadcapincedabeaiguetoneaiaea 130 Executive Summary In today s society robots are everywhere whether is it just simply a toy design to entertain children a computer that perform a task at a scheduled time a machine that is suppose to help workers perform his or her job faster and better a car that can take someone from point A to point B without the use of a driver one good example would be a Taxi Cab that can drive you anywhere you want within a certain area Or as we have seen in many movies a robot can be design to be a spy used for a number operations All these different types of robots have one important thing in common which is a certain level of intelligence a program that tells it what to do or look for
44. ch it walks as its gait Walking can be viewed as controlled falling Thus not only must the 6 legs relatively move in a meaningful fashion but they must also provide enough balance and cohesion so the robot doesn t fall flat on its chassis This will be much easier said than done The reason for this is that there will essentially be 18 degrees of freedom that the Drive system must control and it must be done simultaneously If a single leg is not appropriately placed or does not touch down on time and the remaining legs do not compensate for its error then it will likely topple right there on the spot In fact the initial testing phases will consist of a group member walking along the hexapod which is trying to walk too but tends to fall and making sure that no important electronics are damaged nor the Mechanics system is damaged whenever the robot takes a plunge Although a series of sensors could be installed on the robot to assure proper gait this would not only make for an incredibly bloated design but would also seriously increase the overall cost of the project As stated earlier a goal that runs parallel to the completion of a working project is to design it well and efficiently Therefore just because 18 sensors or even 36 sensors would provide for near flawless gait it is perhaps not the optimal choice when economic factors are taken into consideration The Research and Investigation section will further address this issue and
45. closer to what they originally had in mind That is although there would be no apparent performance differences and the specifications were roughly identical this model was more aesthetically pleasing The lower curvature of the leg model resembled the hexapod structure that the group had in mind Since all costs would be the same the group simply opted for the more curved leg since in their opinion it looked cooler Figure 11 shown below is a picture of the leg model and the reader can make their own choice Again the leg does not come with a servomotor it is only there for illustration purposes 41 Figure 11 Robot Leg A from www LynxMotion com reprinted w permission Thus it was decided that this model was the preferred leg model and would be the one used for the project However this leg alone would only provide a single degree of freedom hardly enough for the proposed drive system Since the original plan was to first find a suitable leg and then to find suitable joints to articulate it the original plan was to obtain joints after the legs to obtain them separately It was learned during the research phase of this project that many times one goes with their gut instinct which is usually dependent on previous solutions to previous problems However this instinct might not always be the best solution to a problem and in hindsight it often isn t Thus a bit of investigation and study should go towards every decision even if the
46. com images Products Full hbkrblk jpg and use it to explain what we are referring to Thank you very much in advance Sincerely Roberto Miguez Reply Forward James Frye to me show details 1 15 PM 2 hours ago Reply Hello Roberto Yes feel free to use the pictures on our website in your documentation Thanks James pes aes 124 M amp M M UL Search your e mail Reply Reply all Forward Re Picture usage Permission From V Scott Moore vsmoore2 comcast net Sent To sure scott Wed 11 26 08 4 48 PM AJ N a j normil hotmail com On Nov 26 2008 at 12 04 AM AJ N wrote Hello My name is Anselet Jacques and I am a student at the University of Central Florida while doing reaserch for my Senior Design Paper I came across your website I was wondering if I could use the pictures of the Linear and Switching Voltage Regulators on your website as part of my project Your website will be sited as a refference for the pictures Thank you for your anticipated co operation A 3 Microchip Permission From lt Donna Mason microchip com gt To lt ph940620 mail ucf edu gt Subject RE Authorization Request Attachments Mime 822 7963 bytes You got it Just follow the instruction in the information you are good to go Donna Mason Academic amp Design Partner Prograrns Microchip Technology Inc 2355 W Chandler Blvd Chandler AZ 85224 480 792 7870 From Ph
47. ct detection and 3 Green colored object detection These modes are simply for the user to control the robot with the remote control The color sensing unit will be powered on with the main power supply of the robot and will thus always be on 2 1 4 Wireless Communication The robot is to be controlled wirelessly by a conventional Playstation 2 controller that is the version equipped with the cable Using the Playstation 2 controller the user will be able to control the movements the gait and the decisions of the robot The Playstation 2 controller will be part of the wireless unit meant to handle the wireless function of the whole system The robot will also send out to the wireless unit vision related data and data pertaining to decisions made by the user The wireless unit consists of the Interpreter circuit two transceivers one on the mobile unit with the user the other on the robot the Playstation 2 controller The Interpreter circuitry is titled so because of one of its main task is to interpret the data coming sent out by the Playstation 2 controller through its cable The Interpreter circuit s other task is to receive and process data transmitted by the robot and interpret them by displaying them accordingly through the LED display box The Interpreter is built around two microcontrollers that are independent of each other and do not communicate with each other directly i e there will be no direct data traffic between them e
48. d for by the autonomously controlled camera mounted on the hexapod When found the image processing unit will notify the user through the PIC18 that will light up the corresponding LED red LED for red object detected blue LED for blue object detected green LED for green object detected Then the user will make the decision of whether to kill the detected target or to unlock The decision will be sent to the robot s processing unit which will relay it to the PIC18 that will light the LED corresponding to the decision of kill or unlock 88 5 4 2 The Transceivers Obviously two transceivers will be necessary to maintain the RF link between the controller and the robot AeroComm s AC4424 10 transceivers are chosen for this task They operate in the 2 4 GHz ISM band and can maintain data rates up to 1152 Mbps However they come equipped with MMCX Jack for compatible whip antennas 5 5 Power Power Supply Design The robot s power system design is influenced by the different power requirement of its subsystems Given that the power is a DC voltage source that only provides a constant voltage while the subsystems require different voltage levels in order to operate Therefore the robot uses voltage regulators to convert the high source voltage to lower voltages required by the different subsystems A voltage regulator is device that accepts a DC input voltage and produces a DC output voltage In general the output
49. d by the microcontroller handling the data from the Playstation 2 controller In receiving mode Transceiver 1 collects the data from the robot s processing unit transmitted by Transceiver 2 and supplies them to the microcontroller handling the LED display box In sending mode Transceiver 2 collects the data from the image processing unit and the robot s processing unit consolidates them then transmits them to Transceiver 1 which in turn sends them to the microcontroller handling the LED display box In receiving mode Transceiver 2 receives data sent out by Transceiver 1 from the microcontroller handling the interpretation of the data from the Playstation 2 controller and then transmits them to the robot s processing unit which will then convert them into movements or decisions The transceivers are to operate in the 2 4 GHz ISM band and each of them will be equipped with a small compact chip antenna for the sake of size and mobility The LED display system will be made up of four differently colored LEDs Three of them will be red blue and green They will inform the user which color is detected by the camera mounted on the robot No more than one of these LEDs will be turned on simultaneously Only one of them can be on The LED display box will display one color at a time as the camera and the image processing unit will be programmed to detect one color at a time The fourth LED will be transparent it will emit white light It is o
50. d the joints together it was decided that it was not worth it This is another example in the project of trying to balance the expenditure of time and money both are crucial resources The leg and joint packages were narrowed down to two different choices Although one model uses the Robot Leg Pair A and the other model uses the Robot Leg Pair B as shown in Figures 7 and 8 respectively the decision made here would be influenced by more than aesthetics The first package looked at is shown in Figure 12 below it is the rugged 3DOF aluminum leg pair Motors are not included 7 TF NS 47518 ao Figure 12 Rugged 3DOF Alum Leg Pair from www LynxMotion com reprinted w permission The package cost 87 90 two legs and had a shipping weight of 4 Ibs The dimensions were as follows e Hip Hor to Hip Vert 38mm e Hip Vert to Knee Vert Femur 57mm Knee to Foot Tibia 124mm 43 These measurements correspond to the measurements depicted in Section 3 under specifications and can be seen on the figure by looking at it from right to left where the end of each joint or bracket is corresponds to one of the measurements from the top down These measurements are within range of the specifications outlined The second leg package looked at from LynxMotion as well was an identical 3 DOF aluminum leg pair where only the foot to knee portion was changed Figure 13 is a picture of this leg package Figure 13 3DOF Alum Leg
51. de Vcc 3V 4MHz Icc Power Down Mode WDT enabled Vcc 3V 9 15 0 uA WDT disabled Vcc 3V lt l 2 0 uA V acio Analog Comparator Vcc 5V 40 mV Input Offset Voltage lack Analog Comparator Vcc 5V 50 50 nA Input Leakage Vin Vcc 2 Current tacpp Analog Comparator Vcc 2 7V 750 ns Propagation Delay Vcc 4 0V 500 Table 11 The DC Characteristics of the AT90S2313 microcontroller Authorization to reprint obtained from Atmel refer to A 4 Pin Descriptions PIN1 RESET Reset input A low level on this pin for more than 50 ns will generate a reset even if the clock is not running Shorter pulses are not guaranteed to generate a reset PIN 2 PIN 3 PIN 6 PIN 9 PIN 11 PORT D PDO PD6 Port D has seven bi directional I O port with internal pull up resistors PD6 PD0 The Port D output buffers can sink 20 mA As inputs Port D pins that are externally pulled low will source current if the pull up resistors are activated The Port D pins are tri stated when a reset condition becomes active even if the clock is not active PIN 4 XTAL2 Output from the inverting oscillator amplifier PIN 5 XTALI Input to the inverting oscillator amplifier and input to the internal clock operating circuit 28 PDIP SOIC RESET C1 vcc RXD PDO O 2 PB7 SCK TXD PD1 3 PB6 MISO XTAL2 O 4 PB5 MOSI XTAL1 O 5 PB4 INTO PD2 O16 PB3 OC1 INT1 PD3 7 PB2 T0 PD4 8 PB1 AIN1 T1 PDS g 9 PBO AINO GND O 1 PD6 ICP
52. de in considering if time would allow the piece to be custom built by the team member or members themselves for example building the brackets necessary for motor mounting or even the vision unit chassis by taking a trip to the local hardware store and putting some ingenuity and creativity to good use This was perhaps one of the more interesting and challenging aspects of the entire project since navigating the current market is an extremely open ended problem For most of us this was the first experience in parts hunting However all members quickly noticed that the complexity of the markets is quite vast and if good results were to be obtained quickly certain methods were to be generated and adhered to The system decided upon was to obtain a quick form of internet communication where a list of vendors could be shared and any pertinent results posted 34 quickly Since not only do certain subsystems rely on each other for completion but the overall integration of the project does as well the ability to quickly post results and evaluate them was integral to success Also by compiling a list of vendors and quickly notifying each other of current market trends or which companies seemed to be the best in a field search time was drastically reduced In the following sections the detailed research and investigation process for the different subsystems is outlined Competing products are compared and contrasted in relation to both our given spec
53. details will be covered in the specifications section Section 3 2 2 1 3 Vision The vision imaging system includes a color sensor lens assembly microcontroller and LEDs The goals of the image system are to extract information from the surrounding environment of the robot check if what is gathered contains what the user has specified a specific color and then notify the user if it has succeeded The information from the environment will be in the form of reflected light off the object being detected by the color sensor unit The light will enter or not enter an array of photodiodes depending on what color the sensor unit is set The array of photodiodes have color filters which is what the user is actually controlling when he she selects a color Those reflected light rays are tested against a set programmed threshold Depending on the intensity of those collected light rays the threshold may or may not be broken Our system will detect 3 separate colors red green and blue These colors are at separate parts of the visible light spectrum Depending on which mode is selected by the user an output signal in the form of turning on an LED will notify the user The range of vision for our camera is also important It needs to be able to capture moderately wide angle so as to limit the number of snapshots needed There are three separate modes of several operation for our free roaming robot 1 Red color object detection 2 Blue colored obje
54. e quality of Hitec is top notch due to the fact that it includes Karbanite gears one piece printed circuit board and a ball bearing Since the group understood that an extensive build and testing phase would exist it was essential that high quality servomotors be purchased Since the quality of these motors seemed fairly undisputed and was validated by the use of many hobbyists and other robot builders the group felt confident in purchasing them Although cheaper motors of lesser quality were available their reduced cost did not seem to validate the threat of having one of the motors break or be bought defective If one of the 18 motors were to break during the building or testing phase then a brand new motor would have to be bought which would result it not only extra expenditures for the motor but also for shipping cost Since the project would also be on a strict time schedule sitting around and waiting for the motor to arrive could potentially be a huge problem especially if it was on demonstration day Naturally there were several vendors for these servomotors Table 12 below encapsulates vendor information and corresponding price Online Vendor Price www servocity com 17 99 each www trcuniverse com 19 99 each www LynxMotion com 17 99 each www LynxMotion com special 107 94 6 metal horns 17 99 each Table 12 Servomotors vendors 46 In the end the special offer from LynxMotio
55. e X Y and Z registers can be set to index any register in the file Timer Counters with Compare Modes The AT90S2313 provides two general purpose Timer Counters one 8 bit T C and one 16 bit T C The Timer Counters have individual prescaling selection from the same 10 bit prescaling timer Both Timer Counters can either be used as a timer with an internal clock timebase or as a counter with an external pin connection which triggers the counting Programmable Watchdog Timer with Internal Oscillator The Watchdog Timer is clocked from a separate on chip oscillator which runs at 1MHz This is the typical value at VCC 5V By controlling the Watchdog Timer prescaler the Watchdog reset interval can be adjusted The WDR Watchdog Reset instruction resets the Watchdog Timer Eight different clock cycle periods can be selected to determine the reset period If the reset period expires without another Watchdog reset the AT90S2313 resets and executes from the reset vector 3 5 Power 3 5 1 Power Supply System 32 In today s technology robots have become commonplace and are used in a number of different applications Our robot which is intended to be a spy bot it has distinct characteristics such as color sensing abilities The robot is semi autonomous because some of its functions are controlled through a remote control For the robot to operate properly an adequate power supply is needed The components and subsystem of the robot are
56. e appropriate LED indicators 86 Transceivers and Robot The Robot will receive the movement control data from the Playstation 2 controller through the Transceivers and process them accordingly It will also send vision related data from its image processing unit to the Interpreter circuit which will process them and respond accordingly 5 4 1 The Controller Interpreter The Interpreter is designed around Atmel s AT90S2313 and Microchip s PIC18F458 microcontrollers As shown in the diagram below the Atmel microcontroller is the only microcontroller on the circuit communicating with the Playstation 2 controller and the brain behind the emulation of a Playstation 2 console As for the PIC18 it is to collect and process the image data from the image processing unit of the robot through the transceivers 5 4 1 1 The AtomPro 28 M The AT90S2313 main role is to allow the robot to be controlled by the Playstation 2 controller It receives the 8 bit serial data from the controller and spits out the 8 bit data in parallel format to the robot s processing unit through the transceivers It also provides the Playstation 2 controller with a clock line to keep both of them in sync necessary for error free and orderly data traffic Software Design Using an interrupt based approach will allow the AT90S2313 Microcontroller to constantly poll the Playstation 2 controller without having to use an on demand key reader routine The microcontroller
57. e given color it is searching for In these next subsections the overall project will be decomposed into subsystems and the goals and objectives of the individual subsystems will be identified 2 1 1 Mechanics Perhaps the most crucial subsystem is the mechanical one It will be composed of purely structural components and components that provide both structure and enable motion If this system is not properly built all other systems will fail to adequately perform It can be viewed as the physical framework or skeleton of the robot before any electron is manipulated Structural components are the pieces that will house and support the electronics necessary for the robot The structural components must also be able to support the robots interaction with the ground that is be able to balance it while it is still and prevent collapse during movement These components not only include the main body chassis but also the supporting legs and its connections to the body The components must be capable of carrying loads resisting body forces and if necessary providing adequate ventilation for electronic equipment Since a stationary robot would not be much fun and would defeat the purpose of having legs anyway a method of movement must be implemented In order to provide movement as a hexapod motion will be generated by mechanical components that can rotate or pivot about a certain axis Some type of actuator can then intelligently provide t
58. e linear regulators have built in compensation and therefore maintain their stability without any external components However other linear regulators do require a capacitance connected from the output lead to ground to assure regulator stability Linear regulators therefore work by taking the difference between the input and the output voltages and burning it up as waste heat Therefore using the linear regulator also drives the need for a heat sink to conduct away all the unwanted heat from the circuit The amount of heat produced depends on the difference between the input and the output voltages i e the voltage difference In our design the difference in voltage levels is quite small and the effects of heat will be negligible There are three basic types of linear regulator designs The Standard Linear Regulator The Low Dropout or LDO Linear Regulator and the Quasi LDO Linear Regulator The most significant difference between these Linear Regulator types is the Dropout Voltage The dropout voltage is defined as the minimum voltage required across the linear regulator to maintain output voltage regulation Therefore the lower the regulator dropout voltage the more efficient the regulator will operate The regulator that operates with the smallest voltage across it dissipates the least internal power and has the highest efficiency The Low dropout regulator requires the least voltage across it for continued operation while the standard regulato
59. e same plane as the vertical hip joint To better illustrate this setup a diagram is provided in figure 2 below The angular rotation for the knee joint and the hip joint are depicted by the first two double arrows respectively while the horizontal rotation of the hip joint is depicted by the first arrow from the right that appears to be going into the page The knee joint and the vertical hip joint are to provide motion in the same two dimensional plane To provide maximum flexibility in the design of the robot s gait it would be desirable if each of the joints had a range of motion of 140 or 70 to the left or right from its centered position Several walking algorithms can be designed and since there is no consequence in providing extra flexibility but there certainly is in providing too little flexibility it will be best to err on the side of caution Even if the current gait will not take advantage of the entire range of motion present future gaits with either a more advanced algorithm or more powerful motors could do so Each joint must also have sufficient room to mount the motor that will control it A direct interface between the motor and the joint is desired without the use of any ancillary mechanical devices such as gears 12 Figure 2 Concept diagram of leg with joints and respective range of motions 3 2 Drive Many of the specifications for the drive system will necessarily be a function of the mechanical system
60. e with the increase of intensity of incident light Photoresistors are characterized by a light and dark resistance These are the resistance of the device when it is in complete or near darkness and the resistance of the device when intense light strikes it so that it is at its lowest 52 possible resistance These two resistance values vary from device to device even in devices manufactured from the same process and factory Phototransistors increase their gate voltage as incident light intensity increases This allows current to flow from the base to collector It works exactly like a bipolar junction transistor except that incident photons increase the energy of electrons in the gate Like the photoresistor there is a light and dark characteristic The phototransistor is characterized by a light current the current allowed by the gate when in full lighting and by dark current the current allowed by the gate when in darkness Photodiodes work in a similar fashion While researching parts that would be a good fit for our circuit we had to take several things into account and make some assumptions One is that our robot will be operating in normal room lighting conditions The other is that the objects we wish to detect will have to be relatively close Some research turned up two color sensors that work on the principle of turning light intensity into frequency The more intense the incident light is the higher the frequency of square
61. ed and then goes through the sequence of moving each leg with a time step in between each Afterwards it again waits for an input signal to determine what its next direction will be 5 3 Vision and Color Sensing 5 3 1 Color Sensor In lieu of the camera and FPGA microcontroller implementation we chose the color sensor light to frequency generator The unfamiliarity with the VHDL language and testing and building with FPGAs in general led us to look at microcontrollers The microcontrollers were very easy to use but definitely had space limitations and we did not want to worry about an external RAM module for frame storage The Interfacing the camera and microcontroller or FPGA proved to be extraordinarily difficult for the time allotted and we began testing photoresistor and phototransistor circuits We chose the TAOS TSL230RD light to frequency generator housed in the PICAXE module with the lens assembly Its ease of use and ease of interfacing were the deciding factors T EREC une eS Figure 29 PICAXE Color Sensor The PICAXE Color Sensor will be the name used from now on in referring to the TAOS TSL230RD lens assembly combination The unit features 2 bright white LEDs for illuminating the object which is being detected This ensures that all colors of the spectrum will be available to be reflected back into the color sensor since white light contains all wavelengths The lens assembly helps focus only light directly ente
62. ed by writing the data to be transmitted to the UART I O Data Register UDR Data is transferred from UDR to the Transmit shift register when e A new character has been written to UDR after the stop bit from the previous character has been shifted out The shift register is loaded immediately e A new character has been written to UDR before the stop bit from the previous character has been shifted out The shift register is loaded when the stop bit of the character currently being transmitted has been shifted out 30 The receiver front end logic samples the signal on the RXD pin at a frequency 16 times the baud rate While the line is idle one single sample of logical zero will be interpreted as the falling edge of a start bit and the start bit detection sequence is initiated Let sample 1 denote the first zero sample Following the 1 to O transition the receiver samples the RXD pin at samples 8 9 and 10 If two or more of these three samples are found to be logical ones the start bit is rejected as a noise spike and the receiver starts looking for the next 1 to 0 transition If however a valid start bit is detected sampling of the data bits following the start bit is performed These bits are also sampled at samples 8 9 and 10 The logical value found in at least two of the three samples is taken as the bit value All bits are shifted into the transmitter shift register as they are sampled The baud rate generator is a frequency divider
63. ely provide two dimensional structures SuperDroid Robots provided much more promising services However they either required CAD drawings or would design a CAD drawing for us What was quickly realized was that even if the team opted for having a company build the chassis the custom design was still going to come from the team And if the design did not come from the team the chassis would be way out of our budget It seemed then that the best solution given the current constraints of our project would be to search for an already designed and already built chassis sold by a robotics vendor At this stage in research if a viable chassis was not found for our hexapod robot either resource allocation or project specifications would have to be altered Either a different chassis would be required or extra time and money would have to be spent in custom building the body chassis 4 1 1 3 Prebuilt HexCrawler Hardware Kit After significant searching online three choices for the body chassis were discovered The first choice looked extremely cool and actually solved multiple problems for us right off the bat It was the HexCrawler Hardware Kit from www crustcrawler com The kit essentially solved the entire problem of building a mechanical system since it already included the legs and the joints coupled with the body chassis The only mechanical part left would be the camera chassis that would be mounted on top of it A fully assembled kit is shown i
64. emperature Storage Temperature 40 Charge 100 Charge 0 C 32 F 2 loss after one year 6 loss after one year 25 C 77 F 4 loss after one year 20 loss after one year 40 C 104 F 15 loss after one year 35 loss after one year 60 C 140 F 25 loss after one year 40 loss after 3 months Table 15 Permanent capacity loss versus storage conditions Nickel metal hydride Batteries NiMH battery technology was invented by Stanford Ovshinsky The first consumer grade NiMH batteries began to appear in the mid 1980s In 1994 his company ECD Ovonics partnered with General Motors to develop high performance NiMH batteries for the GM Ev1 electric car Currently NiMH technology is licensed by Cobasys which is a joint venture between Chevron Corporation and ECD Ovonics NiMH batteries and chargers are readily available in retail stores in common sizes AAA AA C and D They are not expensive and the voltage and performance is similar to standard alkaline batteries in those sizes they can be substituted for most purposes The ability to recharge hundreds of times can save a lot of money and resources The characteristics of Nickel metal Hydride batteries include its low internal resistance which is advantageous for high current drain applications This low internal resistance allows the NiMH cells to deliver a near constant voltage until they are almost completely discharged NiMH also has a low self discharge rate
65. erefore only three legs need be analyzed in any direction By making the center of the directional heading on the middle of the three legs front legs which are coupled to the back legs to be analyzed there exists symmetry between the left and the right legs Therefore all that needs to be done is derive a model for the left or right leg to move mirror it on the opposing leg and derive a model for the front leg Thus the entire walking algorithm can be simplified to deriving suitable models for just a single front leg and a side leg Deriving a model for this type of situation is somewhat intuitive if one only considers the two legs at once it seems like a hobbled human being The side leg should raise its vertical hip position move its hip position horizontally extend its knee and then lower its vertical hip position This will be a side step forward The front leg should then raise its vertical hip position maintain its horizontal hip position since it is in the direction of movement and extend its knee This will be a step forward and this step will return the side knee joint to its proper position Then the alternate side leg will mirror the sequence of the side leg This is the model derivation concept where the actual angular values and consequently servomotor positions will be dependent upon the length of the legs themselves Program Execution In order to better illustrate the execution of the gait algorithm a block diagram wa
66. ermission Push the second complementary leg piece over the spacer as shown in Figure 45 This locks the servo in place and finishes the foot to knee portion of the leg Figure 45 Servo locked by leg structure from www LynxMotion com reprinted w permission Insert the appropriate screws to fasten both the servomotor and the legs together as shown in Figures 46 and 16 Figure 46 Screws to fasten motor and leg from www LynxMotion com reprinted w permission Attach the rubber end cap onto the end of the leg It should cover all the way past the nut This is shown in Figure 47 95 Figure 47 Rubber cap inserted from www LynxMotion com reprinted w permission Take the joint or servo hinge shown in Figure 48 and place it over the servo as shown in Figure 48 This is the interface of a motor with a leg joint Figure 48 Hinge shown amp used for knee joint from www LynxMotion com reprinted w permission This concludes construction of the first portion of the leg The next portion to be assembled will be the hip joints with their motor connections 6 1 1 2 Hip Joint Assemblies Attach a ball bearing to the multi purpose bracket as shown in Figure 49 Refer to Figure 50 for detailed information on how to do this Note this ball bearing is part of the body chassis This bracket is necessary since the fate of the legs through the hip joint is to be connected to the body chassis 96 Anm DG en COBB Anm Loc
67. ers because it can be programmed in BASIC language which permits the architecture of the code to be simpler and more perceivable BasicMicro provides the development program for free AtomPro IDE for download on their website www basicmicro com The Atom Pro 28 M features 32 KB of Program Space or Flash 2 KB of User Memory or RAM 4 KB of User Data Storage or EEPROM It has 20 Input Output pins 8 of which are Analog to Digital capable I O pins It comes equipped with a built in 5V regulator 3 Hardware Timers and 3 Hardware PWM I O Pins It is capable of interrupts and can perform 32 bit floating point math and 32 bit integer math Some additional characteristics are provided in the table below Characteristic Value Units VIN Range min max 6 9VDC VCC Range min max 4 9 5 2VDC Current Draw Sleep Mode 10mA Current Draw maximum 50mA Current Draw Idle 20mA T O Logic TTL I O Voltages Low High 0 0V 5 0V T O Maximum Current 3 mA sink 3 mA source Temperature Range 20 to 75 C Table 3 Another reason the Atom Pro is convenient is the fact that a development board or any other complex circuit is not required to program this microcontroller It can be programmed from a RS232 serial port Four connections four pins of the microcontroller to a RS232 DB9 cable are required or a USB to serial adapter The diagram below shows the necessary connections 21 DB9 View Loo
68. feature will be put to very good use while designing the walking algorithm since it would allow one to reduce some of the complexity behind controlling all 18 degrees of freedom Figure 16 below shows the controller 47 Figure 16 SSC 32 Servomotor controller from LynxMotion reprinted w permission No other controller was found on the available market that provided both such a large amount of servo control and the features available Thus for 39 99 this was considered a good purchase 4 2 2 Gait Algorithm The gait or walking algorithm must be able to translate the 18 rotations given by the motors to the joints and legs into linear motion of the robot itself Exactly how many sequences will be present per each step of the robot is not discussed here but in the later sections involving design What will be discussed here are the methods investigated for being able to derive a model and algorithm that works as specified 4 2 2 1 Evolutionary Computation One approach considered was that of evolutionary computation Since deriving a working model of all 18 different motors and their rotation could turn into a difficult problem one could simply evolve a solution using methods such as genetic algorithms or genetic programming Although this method will be kept in mind during the course of the project the method still involves understanding how each rotation will affect the movement of the robot as a whole It does sidestep having to put
69. ferring data between the 32 general purpose working registers and the I O space I O registers within the address range 00 1F are directly bit accessible using the SBI and CBI instructions In these registers the 31 value of single bits can be checked by using the SBIS and SBIC instructions When using the I O specific commands IN OUT the I O addresses 00 3F must be used When addressing I O registers as SRAM 20 must be added to this address The CBI and SBI instructions work with registers 00 to 1F only Internal and External Interrupt Sources The AT90S2313 provides 10 different interrupt sources These interrupts and the separate reset vector each have a separate program vector in the program memory space All the interrupts are assigned individual enable bits which must be set one together with the I bit in the status register in order to enable the interrupt The lowest addresses in the program memory space are automatically defined as the Reset and Interrupt vectors The lower the address the higher is the priority level RESET has the highest priority and next is INTO the External Interrupt Request 0 etc General purpose Working Registers Each register is assigned a data memory address mapping them directly into the first 32 locations of the user Data Space Although the register file is not physically implemented as SRAM locations its memory organization provides great flexibility in access of the registers as th
70. from the console or the interpreter is transmitted to the controller After the transmission is done the line is raised to high 1 and from then on if it stays high the controller will ignore all activity on the COMMAND PIN PIN 7 CLOCK PIN The color of this line is blue The Playstation 2 console or in our case the interpreter circuit transmits its clock signal to the controller through this pin keeping them synchronized Both the controller and the console transmit data through PIN 1 and PIN 2 respectively at the falling edge of the clock and receive data through PINS 2 and 1 respectively at the rising edge of the clock The maximum clock rate is about 192000 bps PIN 8 N C This pin is not connected to anything There is no wire connected to it Moreover there are Playstation 2 controllers that do not have this pinout If there is leave it unconnected PIN 9 ACK PIN ACKNOWLEDGE The line to this pin is green The controller transmits through this line and its role is to inform the console or the interpreter that the controller is still active After the last bit of each byte is transmitted to the controller the line is pulled low within 60us while the ATT PIN PIN 6 is held low regardless of the clock If this pin is not pulled down within that time frame after the last bit is transmitted the console or the interpreter will start interrogating other controllers on the data port 17 Single Data Byte Format
71. fter the battery has been less than 25 discharged at about 1 42V Also after a Deep Discharge they can be brought to their original high capacity charge only after many frustrating charge discharge cycles thus their Theoretical high capacity is available only for Emergency cases Unlike NiMH rechargeable batteries alkaline batteries are normally not sold with a nominal capacity Alkaline has a high internal resistance and a high thermal coefficient of resistivity the faster you drain an alkaline the higher percentage of the load it dissipates as heat Therefore the capacity of an alkaline battery is strongly dependent on the load even at moderate loads A AA sized alkaline battery might have an effective capacity of 3000 mAh at low power but at a load of 1000 mA which is common for digital cameras the capacity could be as little as 700 mAh Below table 16 shows a comparison of the different types of rechargeable batteries 65 Nickel Metal Nickel Lithium Ion Alkaline Hydride Cadmium Li ion NiMH NiCad Voltage 1 25V 1 25V 1 75V 1 50V Capacity High Low High High initially but decreases with use Capacity in 1300 2500 600 1000 21000 2000 initially mAH AA type Capacity in 2200 11000 1800 4500 Not available in 8000 initially mAH D type this size Performance Good Good Good Poor in high drain devices Recharge Excellent Excellent Good Good Ability Recharge
72. g of the vision unit chassis would not be investigated since the same problem that occurred for the body chassis would occur here Although quick designs for the vision unit chassis were drawn on whiteboard and ideas were thrown around during a meeting it was decided that someone could check online vendors simultaneously to see what was available A suitable vision unit chassis was quickly found online and this option was abandoned However the team 39 would like to note that a vision unit chassis is easily constructed and should not be contracted unless it is found to be relatively inexpensive to other considerations 4 1 2 2 Prebuilt LynxMotion provides an add on deck to their body chassis The add on deck has a mounting hole on the top panel for a motor which is perfect for our application Since the add on deck was only 9 95 and could easily be added to our existing body chassis it was chosen immediately Perhaps further investigation might have yielded a competing chassis but the opportunity cost of such a search was thought to be too much when this one was right in front of us Although the chassis did not exactly meet the initial specification of having 5 inches below for electronics housing due to the fact that it can connect directly into the existing body chassis and that it already has a mounting hole this was considered not to be a problem An add on deck is shown in figure 9 below Figure 9 Camera Chassis from www Ly
73. ge sensors present the burgeoning CMOS technology s greatest contribution to image science Superbly small scale and lightweight low power consumption and excellent image quality present a very attractive option In fact these are main component in what is known as the consumer web camera typically used for video conferencing The drawback to using these web cameras for robotics applications are the proprietary video decoders and embedded software that is part of the integrated system Thus the engineer or builder must reverse engineer these cameras to achieve what he or she wishes if it is necessary Since countless companies make these web cameras with little or no detailed technical specifications as to how they acquire process and communicate image data it makes little sense to blindly select one for this project The obvious reason being is connectivity to the image processor Will it interface correctly Can the image data be manipulated and read as desired These unknowns can be eliminated by choosing the CMOS image sensor Simple reliable low cost and high quality the CMOS image sensor is typically found in as previously stated digital web cameras small low cost digital still cameras or cellular phones that feature digital camera capabilities CMOS image sensors can be purchased without a lens assembly or with a lens assembly as shown below in Figures 17 and 18 49 z Laminate Substrate CMOS CHIP Lens Mount Sens
74. gh to provide security is the second test All joints should be calibrated to pivot loosely in their given range of motion and should be checked that they do not fail at or exceed the limits of their ranges of motion Any loose joints should be tightened and any joints that are too tight should be loosened If only human bodies were this easy to fix One should pay particular attention to the procedure followed when checking the joints since when testing the drive system one might find that the joints are still too stiff for the given motor torque and must be loosened appropriately Iterative testing between the mechanical and drive subsystems will be followed in order to get a strong yet smooth rotation of the joints and thus gait 7 3 Drive First a test program will be created to test that the full range of motion for each servomotor is working as specified If this were not so then clearly no other portion of the drive system would work The second test will be that the robot is able to walk in any of the given directions as specified That is a test program will be loaded into the drive in order to examine the capability of the robot to walk in an arbitrary direction At this point in time the drive system will be tested independently of the communication system and thus no wireless control is being given It will be checked that the drive system is meeting the necessary specifications of clearing rate and speed and if it isn t then eithe
75. gth from the base of the leg or the foot to the knee joint should be between 5 6 inches the length between the knee join to the vertical hip joint should be between 2 5 3 5 inches and the length between the vertical hip joint to the horizontal hip join should be between 1 5 2 5 inches This means the leg can have a maximum length of 1 foot or a minimum length of 34 of a foot These ranges are not steadfast and will be used as a guide to search for a working leg The total leg length was decided due to its proportion with the chassis and the length ratio for the joints was chosen to be commensurate with their load ratios e g the length from the foot to the knee joint is the 11 longest since it will carry the heaviest load Figure 1 below better illustrates these ratios their meaning relative to the leg and joints and consolidates the measurement ranges It depicts from left to right the foot to the knee the knee to the horizontal hip joint the horizontal hip joint to the vertical hip joint the connection to the body chassis body not shown a ee eee ee Figure 1 Concept diagram of leg with measurement ranges 3 1 3 Joints Each leg will have three distinct joints Each joint will be rotated with a motor There will be two hip joints and a single knee joint The two hip joints will be orthogonal to each other one will provide vertical rotation and the other horizontal rotation The knee joint will provide rotation in th
76. h usually the regulator and a bypass requires inductors diodes capacitor capacitors transistors filters etc Cost Low Medium to high Table 16 Advantages and disadvantages of Linear and Switching Regulators As seen from the table above both converters have their unique advantages and disadvantages depending on its application The choice of a converter for the robot will be to satisfy its cost requirements Therefore considering that it is operating at very low voltages and the heat waste is negligible the robot is more inclined to use the low dropout linear regulators to build our power supply for the rover The LDO regulates the input voltage providing the desired output voltage and it works with a lower voltage across it before it stops regulating A popular example of the low dropout regulator is the LM2940 CT 5 0 It is a low dropout regulator that fits into the same socket as a 7805 but can still regulate with less than 1 volt across it For instance using a regulator like this will guarantee that a 9 volt output from our 10 volt battery source is sufficient to still provide around 9 volts to our camera for the video vision operation of the robot The use of the low dropout regulators can be considered an upgrade from the conventional 7805 style regulators that are commonly used the electronic circuits However if we are upgrading a power supply to an LDO we must make sure that we have enough output capacitance to stabil
77. han the required voltages of the subsystems and a buck converter is design to produce a lower output voltage than the output Since switching regulators are more expensive than linear regulators we will probably use linear regulators as well Both linear and switching voltage regulators have their uses and both have their advantages and disadvantages To better have a clear picture on when using a linear of switching voltage regulator would be appropriate or better for a circuit table 16 shows a comparison of both types of voltage regulators 73 Parameter Linear Voltage Regulator Switching Voltage Regulator Function Step Down only output Step up or Step Down can voltage must be less than produce multiple outputs input voltage Efficiency Low to Medium High size Small to medium in Large for low power may portable design may be be smaller in applications larger if heat sinking is where linear require heat needed sinking Weight Light Medium Linear and Load Low line and load Low line and load Regulation regulation percentage regulation percentage Output Ripple Negligible Large Noise Low and better noise Medium to high due to rejection rippel Transient Response 20us 1 0ms Hold up time 1 0ms 2 0ms 20ms 30ms Waste Heat High if average load and Low components usually voltage difference are high run cool for low power levels Complexity Low usually only requires Medium to hig
78. he objectives outlined in Section 2 while staying to the specifications outlined in Section 3 as much as possible Before research even begun it was expected that all of the specifications would be difficult to follow there is a far cry between knowing the optimum piece needed for construction and actually finding it Therefore the research aimed to find the best fit possible with whatever means were available Beyond the technical aspect of research and investigation each team member also focused on procuring parts that kept us within our budget That is even if a part that fully met specifications was found the cost of obtaining it was carefully balanced against its importance in the overall design of the project By the very design of our approach to the problem of building the robot it has been split up into a multitude of smaller problems If a particular solution to one of these problems is simply too expensive to implement then another solution must be found The process of outlining specifications research and designing the project was both an iterative and recursive process Even if a particular component is found that fully matches specification there is no need to immediately believe that this part is the optimal combination of both price and performance on the market Thus even if a matching component is found an earnest attempt was made to find other competing companies that offered similar components An earnest attempt was also ma
79. he robot is working as it is expected to work Since the project has been split up into various subsystems each subsystem will be tested individually prior to integration This method prevents the team from having to concoct very elaborate and complicated testing strategies due to having various subsystems integrated at once and greatly reduced the potential problem space For example if all of the systems were integrated and an error occurred it would be difficult to discern which subsystem failed and caused the error As an example consider the event where the robot fails to locate a color The error could obviously be a result of the color sensor system or perhaps it could be a result of the communication system Perhaps the robot is properly locating objects but it is just not sending the signal back to the remote control properly Another reason might be that the signal is being transmitted just fine but the controller is having difficult receiving it In order to eliminate the problem space of errors each subsystem will undergo a battery of tests itself and then the subsystems will be tested in each integration phase Finally of course the entire robot must be tested in order to ensure proper functioning and seamless amalgamation 7 1 Testing Environment First of all in order to test the robot we will need an open area somewhere on the UCF campus The testing environment will need to have enough space for the robot roam around while
80. he robot will be built and Section 6 1 will go into detail of how both chassis will be put together 5 1 2 Leg Connections Similar to the chassis the leg packages bought obviate the need of preparing a meticulous mechanical design However there are still various ways to connect the working legs to the chassis The method of connection is an important one since the walking algorithm will of course be dependent upon their particular geometry and configuration One of the specifications for the chassis was to provide leg connections all on the same two dimensional plane and this specification was met by the body chassis obtained In order to maximize this setup and allow for maximum range of motion during the robot s gait all legs will be connected in such a manner that their vertical length is perfectly orthogonal to the chassis and the horizontal width is perfectly flush to the connection Satisfying one requirement should satisfy the other Pictures are present in Section 6 but to help envision such a connection it is helpful to consider each leg as a pillar and the body chassis as a ceiling the optimal configuration is to have all pillars perpendicular to the ceiling they are holding up This leg configuration will enable the joints to exhibit a maximum range of motion since the legs will be in a position where the relative distance between each leg is a maximum Although many other configurations are possible such as three legs at a give
81. hen the controller responds 0x5A meaning Sending data while the console or the interpreter idles The console or the interpreter is ready to receive key data from the controller As shown in Table 1 below each key has a single assigned bit The bits assigned to the keys are normally high until the keys are pressed which changes the corresponding bits to 0 The analog sticks though cause the controller to send several bytes that inform the Playstation or the interpreter of their position or pressure 18 Playstation 2 Controller in Analog Red Mode Byte COMMAND DATA Number Line Line 1 0x01 idle 2 0x42 0x73 3 idle OxSA 0 1 2 3 4 el 6 7 4 idle data select L3 R3 start up right down left 5 idle data L2 R2 Ll R1 A X E 6 idle data Right Joystick left 0x00 right OxFF 7 idle data Right Joystick up 0x00 down OxFF 8 idle data Left Joystick left 0x00 right OxFF 9 idle data Left Joystick up 0x00 down OxFF Table 1 The first three data bytes at initiation of conversation and the key assignments Authorization for reprinting pending 3 4 2 The Xbee OEM RF Module Transceiver 19 Figure 3 The Xbee OEM Module is a low cost low power wireless transceiver It requires minimal power and provides reliable delivery of data between devices It operates within the ISM 2 4 GHz frequency band Long Range Data Integrity Indo
82. hese edges connect The image processor must have programmed definitions of the colors Therefore it must search for blobs of the user specified color The computation must take place before the next image is to be acquired or before the next obstacle is to be found This should not be a problem given our low frame rate specification The source code for the image processor will be written in VHDL if using an FPGA or C if using a microcontroller and stored in an on board ROM chip The image processor will look for adjacent pixels with the same value 0 to 255 If there is a high percentage of one color in one area of the screen otherwise known as a blob an object will be detected What percentage like colored pixels of the total number of pixels will denote is what must be determined If we select a percentage too high then only objects up close will be seen If we select a percentage too low then too many objects will be detected because the robot will see too much like erroneous objects We will set the percentage at 15 Therefore if a group of like colored adjacent pixels make up 15 of the total number of pixels or more than this blob of pixels will count as an object Once more testing can be done another percentage may be applied 3 4 Wireless Communication 3 4 1 The Controller The Playstation 2 controller will be used to control wirelessly the many functions of the six legged robot including its motion and its
83. his rotation to cause motion It is crucial that whatever mechanical components allow for movement are not easily twisted or broken with a bit of excess force They must be able to withstand forces greater than we expect since there will always be certain outliers in force application and once a component starts to malfunction it will only get exponentially worse Inadequate provision at this stage could possibly produce a robot that works well at first but cannot sustain repeated testing due to the wear and tear of its mechanical parts The objectives of this subsystem are to provide a stable housing structure and a platform capable of providing reliable movement for the hexapod robot The Drive subsystem definition in the next section will explain the concept of movement as it relates to the hexapod robot and how it will be generated 2 1 2 Drive This is the subsystem responsible for not letting the robot just sit there and accumulate dust Its overall objective is to provide a system of movement for the hexapod robot In order to do so it must somehow articulate the 6 legs along their three degrees of freedom in a meaningful fashion to produce movement Since we have already been referring to the pointed chunks of material that will be protruding from the robot s chassis as legs it seems logical to now refer to its movement as walking We will refer to the hexapod s movement in any direction as walking and the method or algorithm by whi
84. hoar e n a ie tensa a eas bodes ee een ae ee 89 Bo POWe Eron roe ee eee a 89 Section 6 Building Prototype isissesssisesversesisirecaasasaesa agvarteavtaaeestsvnecaseasdanaiaesaeeeaubannentseyes 93 6 l Mech nics and DIVE ariassan ei ia aai dats iea aasi n aeni 93 64 1 Les and Motor Assembly rono i a E ee ee 93 0 251 DAVE ma a re te E OR A E E Ee A Pee NS 101 ORSAI E A A E E E E E E E TEA ETEA 101 OCH ONE KAS EEE AET EEEE A E EEEE 102 MECHANICS N E E E E A E EE 103 PADIVE a e Baie E T E E bbs R E T E E 103 TA NASI OM nainn aan a a a as SS TE aa EE 103 7 5 Wireless C ommu nic tl f e ai a a A a a a A A AAS 105 7 6 Wireless Communication and Drive and Vision ccccccccccececeesessnseceeeceeeeeeeens 108 To Final TESS EE E E RS A LAL MTN nS N A E 110 Secton 8 Desig Summary oenen ani a a esaet 111 Section 8 1 Mechanics and Drive anou nnan a E a 111 SOCH TOTEAA AITO EEEE NENEA E E ET 115 Section 8 3 Wireless COMMUMNICALION ccccccccceesseesssececececeeeessnseceeeceesesenenteaeees 115 SECON 9 4 BPO WEIS n aer a a E E R Na A a ae Masvaeea 117 Section 9 Administrative Content ccccccessssececececeesessnsecececeeecsesesssseeececeeseeenerteaeees 120 BO MERU OU i Aad E a A a ooo a E 120 O RASITA na ET oT EEE E EEA E E T ERT 121 Appendix A Reprint Permissions s sssssssesssssseessesessstesstessrssersseeesseeessresseesseesseeesseee 123 A 1 CrustCrawler Products Permission cccscsscccccccceesesessececec
85. hough originally intended for consumer electronics Lithium ion batteries are growing in popularity with the defense and aerospace industries because of their high energy density One of the latest uses is in hybrid electric cars and eventually electric vehicles as commodity cells The advantage of the Lithium ion batteries includes its ability to be formed into a wide variety of shapes and sizes so as to efficiently fill available space in the devices they power Li ion batteries are lighter than other batteries which is good for our robot because we want it to be relatively light and the energy is stored in these batteries through the movement of lithium ions A key advantage of using Li ion chemistry is the high open circuit voltage that can be obtained in comparison to aqueous batteries such as lead acid nickel metal hydride and nickel cadmium The disadvantages of the Li ion battery is that its life span is dependent upon aging from time of manufacturing regardless of whether it was charged and not just on the number of charge discharge cycles Also as batteries age their internal resistance rises This causes the voltage at the terminals to drop under load reducing the maximum current that can be drawn from them Eventually they reach a point at which the battery can no longer operate the equipment it is installed in for an adequate period Li ion batteries are generally more expensive but not as durable as nickel metal hydride or nickel cad
86. ience desired would probably best come in the form of designing and building their own project from scratch Since the different members each had different expertise and different interests the initial phase of deciding what to build had the restriction of providing something that was of interest to each group member This is why the group decided to build a robot A robot design easily provided all of the areas of interest that the members wanted There would be no real practical purpose to the robot besides building it and having it work it would just be a massive learning experience Since the group members were interested in building a novel control system radio frequency communication computer vision sensory attribute and power electronics our project just combined all of this together into a walking hexapod robot with artificial computer vision and radio control Naturally powering this diverse system would be a challenge in and of itself and the student interested in power electronics was content with the challenge ahead The group also explicitly decided that elegance in design would not be a concern In other words although certain problems might have been solved by other methods wheels only infrared vision programmed control instead of remote wired power supply it was decided to expressly make things more difficult in order to provide ample testing and learning grounds Thus pragmatic issues were not concerns the design process and
87. ifications and objectives and the choice made for the design portion is shown For purposes of presentation the final solution or product shown in the investigation portion will always be the design choice made for the project Previous options are also demonstrated to show the research process and enable readers to make decisions for themselves 4 1 Mechanics 4 1 1 Body Chassis 4 1 1 1 Handmade Custom The first mechanical component investigated was the body chassis since all other mechanical components will depend on it and the rest of the project will depend on the mechanical components At first thought the group felt reasonably confident that building the body chassis ourselves would not be a big issue If it was just to be a hunk of material that would be providing support there shouldn t be much to making one Although simply fashioning a piece of material to be of a certain size and weight in order to function as a chassis is not very difficult making sure that it can easily enclose the necessary electronics and provide adequate ventilation further complicated the matter Also the connection joints to the legs were specified to all exist on the same two dimensional plane for ease of construction so the chassis had to somehow provide these connection points Although initial plans were discussed and it certainly was possible to construct the chassis it was decided that designing a chassis building the chassis and making sure tha
88. ile unit and the robot one let it be labeled Transceiver 1 on the mobile unit which consists of the Playstation 2 controller and the two microcontrollers covered above the other labeled Transceiver 2 on the robot In sending mode Transceiver Icollects and transmits to Transceiver 2 the parallel data supplied by the microcontroller handling the data from the Playstation 2 controller In receiving mode Transceiver 1 collects the data from the robot s processing unit transmitted by Transceiver 2 and supplies them to the microcontroller handling the LED display box In sending mode Transceiver 2 collects the data from the image processing unit and the robot s processing unit consolidates them then transmits them to Transceiver 1 which in turn sends them to the microcontroller handling the LED display box In receiving mode Transceiver 2 receives data sent out by Transceiver 1 from the microcontroller handling the interpretation of the data from the Playstation 2 controller and then transmits them to the robot s processing unit which will then convert them into movements or decisions The transceivers are to operate in the 2 4 GHz ISM band and each of them will be equipped with a small compact chip antenna for the sake of size and mobility The LED display system will be made up of four differently colored LEDs Three of them will be red blue and green They will inform the user which color is detected by the camera mounted on the rob
89. illipe Jean Jumeau mailto ph940620 mail ucf edu Sent Friday December 05 2008 11 19 AM To Donna Mason CO8830 Subject RE Authorization Request So I do have your permission provided I write your product PIC18F458 MCU properly in the report 125 p Full view a mM K A 4 Atmel Corporation Permission From De Caro Michael Friday December 5 2008 6 01 PM lt Michael Decaro atmel cam gt To Phillipe Jean Jumeau lt ph940620 rmail ucfedu gt Subject RE Webmaster Authorization Request Attachments Mime 822 3341 bytes View Save As hillipe The due diligence you have indicated in your e mail is compliant with our policies regarding the re use of Atmel copyrighted material You may do so accordingly Sood luck with your design project Regards Michael rom webmaster bounces atmel com mailto webmaster bounces atmel com On Behalf Of Phillipe Jean Jumeau Sent Friday December 05 2008 9 44 AM To Webmaster atmel com Subject Webmaster Authorization Request Dear Atmel Staff or our Senior Design Project at the University of Central Florida we will be using some of your products Since we are building a hexapod robot many of your products are exactly what we need Our documentation needs us to show where we obtained our products and the information on them In order to avoid copyright and other legal issues we need your authorization to use pictures and some texts from your website
90. in answering your questions please complete the following form Contact Information Prefix Mr l Company University of Central Florida Email steven_schultz hotmail com Outside US amp Canada Please enter your complete phone number with Country Code amp Area Code Phone 3132448499 Addressi 469 Alafaya Woods Blvd City Oviedo Country USA xl Problem Description Brief Description of the Problem Note If you need to enter code snippets use the text box below Steps to Recreate the Problem I have no problem I am just requesting approval to use images from the TVP5150 Data Sheet 129 Required First Last Name Steven Schultz Job Title Student FAX Address2 Zip Postal Conde 32765 State Province
91. ink Listed in table 6 below is the duration of the hop and of the hop cycle period Typical Time ms Hop Period 8 Table 6 Duration of the hop and the hop cycle of the AC4424 10 Transceiver Authorization to reprint pending AC4424 AT Commands and Command Mode The AT Command mode implemented in the AC4424 10 creates a virtual version of the Command Data pin The Enter AT Command Mode Command asserts this virtual pin low to enable Command Mode and the Exit AT Command Mode Command asserts this virtual pin high to enable Data When in AT Command Mode the user cannot send or receive RF packets However a period of approximately 10ms exists where if the Enter AT Command Mode command has been sent to the transceiver at the same time an RF packet is being received the RF packet could be sent to the host circuitry before the Enter AT Command Mode command response is sent to the host circuitry Prior to sending the Enter AT Command Mode command to the transceiver the host circuitry must ensure that the RF transmit buffer of the transceiver is empty if the buffer is not empty the Enter AT Command Mode command will be interpreted as packet 23 data and will be transmitted out over the RF This can be accomplished by waiting up to one second between the last transmit packet and the AT Command The host circuitry must also ensure that the RF Packet Size for the transceiver is set to a minimum of s
92. ion of the window all pixels are multiplied against their respective coefficients The final result is then scaled to produce a single output pixel for the centre location of the window This requires several multiplications per pixel of which can be done in parallel In a DSP the number of parallel multiplications would be limiting as to not even mention the length or number of clock signals An FPGA since it is programmed by the user can implement as many multipliers as physically allowed An FPGA has a flexible over DSPs because they are programmed by the user and do not have permanent functions defined by a manufacturer FPGA logic is described using Verilog language or VHDL VHSIC Hardware Description Language Both of which 58 have similarities to C language However it must be noted that writing software in C and describing hardware in VHDL or Verilog are two different types of programming altogether Since the FPGA will be where the robotic system thinks and tells the user what is seen or which direction to maneuver it can be called the brain of our robot There are many advanced and expensive FPGA development boards available with the discriminating factors being the number of logic gates and the on board memory RAM or ROM Logic gate numbers soar to the millions for some boards Most FPGA boards run on 5 V to 12 V DC power or 5 V USB power and do not consume a substantial amount of power I O Buffers Ve
93. it is looking for its target The room will also contain all the colors of various shapes that the robot will need to identify The objects will vary in sizes and colors To show the robot s intelligence and capability to effectively look for the different colors the object will be scattered around the room This will also show effectively the robot s field of vision its ability to walk and the accuracy with which the robot find its target Since it is possible that it may be raining the preferred testing area for the robot would be an indoor open area therefore the testing will be planned to take place indoors instead of outdoors The size of the available testing area will determine how challenging the robot s task will be it will also show how long the robot can run before the battery will need to be recharged 102 7 2 Mechanics The mechanics subsystem will be rather easy to test and fix or calibrate if it is not functioning properly It is an important to make sure the mechanics subsystem is working properly before the integration of any other subsystem because a failing in the mechanics will essentially ensure all other subsystems to fail Hand testing each individual joint and making sure that none are too loose or will be detached or twisted by the strength of the motors takes care of ensuring the structural integrity of the system Then making sure that the joints themselves are loose enough to allow for rotation but tight enou
94. ium has a high life cycle recharge times of 1500 and has a moderate recharge overload tolerance Its output is 1 25V just like NiMH and has a lower self discharge rate of 30 per month It is a mature technology that has been in use since the 1950 s but unfortunately it s toxic and has a low energy to weight ratio second only to lead acid Alkaline Batteries Rechargeable alkaline battery is a type of alkaline battery that is rechargeable This rechargeable alkaline technology was developed by Battery Technologies Inc in Canada and licensed to Rayovac Pure Energy and Grand cell The shapes include AAA AA C D and snap on 9 volt batteries Unless you re looking for an inexpensive rechargeable battery that is ready to use right out of the package without recharging we suggest you avoid them This type of battery is best suited for low drain devices such as remote controls or for devices that are used periodically such as flashlights Chargers designed for NiCad and NiMH batteries are not suitable for charging rechargeable alkaline cells The advantages of rechargeable alkaline batteries include its relatively cheap cost and a high charge capacity Typically 2 Ah for a AA and over 6 Ah for a D cell Rechargeable alkaline batteries also hold their charge for years unlike the NiCad and NiMH batteries The disadvantages of the rechargeable alkaline batteries include its maintenance of a full chargeable capacity for hundreds of cycles only a
95. ix The Enter AT Command mode command is as follows Host Circuit Command 41h 54h 2Bh 2Bh 2Bh ODh Transceiver Response CCh 43h 4Fh 4Dh The Exit AT Command is as follows Host Circuit Command CCh 41h 54h 4Fh ODh Transceiver Response CCh 44h 41h 54h Various commands for the transceiver are listed in Table 4 3 of the datasheet documenting the AC4424 transceiver located in Appendix A 3 4 3 The Microcontrollers 3 4 3 1 Microchip s PIC18F458 MCU The PIC18F458 MCU is a low power 8 bit microcontroller based on RISC Reduced Instructions Set Computer architecture equipped with high speed Enhanced Flash technology and program memory addressing up to 2 Mbytes 24 D O _ o nm fa ao 8rtd8L9ld Figure 4 The PIC18F458 MCU from Microchip Authorization to reprint obtained from Microchip refer to A 3 Absolute Maximum Ratings Operating Temperature 40 C to 125 C Storage Temperature 65 C to 150 C Voltage on any pin with respect to Vss except Vpp MCLR and RA4 0 3V to VDD 0 3V Voltage on Vpp with respect to Vss 0 3V to 7 5V Voltage on MCLR with respect to VSS OV to 13 25V Voltage on RA4 with respect to VSS OV to 8 5V Total power dissipation 1 0 W Maximum current out of VSS pin 300 mA Maximum current into
96. ize the output voltage The commonly used 7805 style regulators have in built compensators and hence do not need additional output capacitors on their output pins to maintain a stable output Typically 0 1NF bypass capacitors on the input and output terminals of the regulator are good for noise reduction and they are also 14 critical for stability The LM2940 series low dropout regulators like most LDO type regulators need a minimum output capacitance In the case of an LM2940 the precise capacitor value is 22 NF This capacitor value can be increased as much as the design allows but a lower capacitor value will not be acceptable Commonly used capacitor values for low dropout regulator stability are in the range LOONF to 1OOONF Sometimes during operation the robot may require large amount of currents currents that the battery may not be handle for example if one of the motors or servos abruptly reverse while the robot is going full speed To handle these large amounts of currents the robot hs a quick release energy reserve In order to provide that energy the use of a large capacitor between 1mF to 10mF which can store a large quantity of energy in the circuit of the robot and release it whenever the robot needs it High frequency noise in the circuit can cause a number of different problems one example regarding the robot would be RF interferences To prevent these high frequency noises a capacitor between the ranges of 10nF to 100nF i
97. k Washer Jmn Steel with 3nm x Biren Standard Mi Stee Screw em E Mulb Purpose Bracket Figure 49 Bracket and connection method from www LynxMotion com reprinted w permission Now attach the two multipurpose brackets as shown in Figure 49 using the screws and nuts depicted in Figures 49 and 50 2 36 x 183 Steel 2 56 x 250 1 4 9 Steel Standard Nut Philips Mead Machine Screw gt g aas Figure 50 Bracket attachment with hardware from www LynxMotion com reprinted w permission Attach the two C brackets as shown in Figure 51 with the two slightly smaller screws and nuts shown in Figures 51 and 52 2 55 x 250 V4 Steel 2 56 x 163 Steel Philips Head Machine Screw Standard Nut al a250 H 4 Figure 51 C Bracket connection w hardware from www LynxMotion com reprinted w permission 97 Connect the two joints that have just been assembled as shown in Figure 52 Figure 53 provides information of how to link the hardware Jmm ID Bem OO BS Inm Lock Washer Imm Stes with Jmm x Gem Standard Nut Steel Screw C Gracket Muib Purpose Bracket Figure 52 Hip Joint connections w hardware from www LynxMotion com reprinted w permission Now the joints have been assembled and what is left is to integrate the motors Attach the servo to the C bracket using the 2 tapping screws and Figure 53 below Make sure that the servo is centered before attaching to the
98. king into Female Connector DB9 View Looking into Male Connector DB9 PIN SIGNAL IN OUT DESCRIPTION ATOM PRO PIN 1 DCD In Data Carrier Detect NC 2 RXD In Receive Data SOUT 3 TXD Out Transmit Data SIN 4 DTR Out Data Terminal Ready NC 5 VSS Ground VSS 6 DSR In Data Set Ready NC 7 RTS Out Request To Send ATN 8 CTS In Clear To Send NC 9 RI In Ring Indicator NC Table 4 The output voltage characteristics of the AC4424 10 Authorization to reprint pending 22 Maximum System Throughput and System Timing When configured as shown in the table above an AC4424 transceiver is capable of achieving the listed throughputs but may not meet these throughputs in the presence of interference or at longer ranges RF Mode Interface Baud Rate Duplex Direction Throughputs bps Acknowledge 115200 Half One way 80k Acknowledge 115200 Full Both ways 40k Table 5 Maximum throughputs of the AC4424 10 Transceivers according to certain configurations Authorization to reprint pending When configured as shown in the table above an AC4424 transceiver is capable of achieving the listed throughputs but may not meet these throughputs in the presence of interference or at longer ranges The AC4424 is a frequency hopping spread spectrum radio Frequency hopping allows the system to hop around interference in order to provide a better wireless l
99. ldered on the same board One of them is to interpret the data from the Playstation 2 controller The relationship between this microcontroller and the Playstation 2 controller will be the same as that between the Playstation 2 console and the controller hence the microcontroller is to emulate the Playstation 2 console It will receive the data from the controller which transmits it in serial format then process it and spit it to the transceiver which will be on the same board The other microcontroller is to collect and organize the data sent out by the robot through the transceivers This set of data is composed of data from the image processing unit of the robot and data concerning some decisions made by the user through the use of the Playstation 2 controller After processing the data the microcontroller will be programmed to display it explicitly to the user through a LED display thereby informing the user on the status of the robot Data Ack Playstation 2 DualShock 2 sso Pa 7 Controller o al Interpreter Circuit ien eia LED Display Command Clock Att Vision Data Controller Data Transceiver 1 Controller Data Transceiver 2 Robot Vision Data Figure 75 Generic block diagram of the wireless system 116 Evidently two transceivers will be used in the wireless unit of the system allowing a two way data transfer between the mob
100. little differently so to develop our program we used the same surface of different colors The program begins by seeing if the SET PAUSE button is set If it is high then it will pause for 5 seconds and allow the user to change the color If it is low then it will determine what color is selected by reading the inputs on input 7 S3 and input 6 S2 Depending on which color is selected it will jump to the respective subroutine Once in the subroutine the microcontroller will sample pulses for a specific time and then test that against a determined from testing threshold If higher than the threshold then the color is a match and the program will light the indicator LED for that color 84 The overall program structure is illustrated below pause 5000 DO WHILE SET 0 DO WHILE SET 0 DO WHILE SET 0 DO WHILE SET 0 ount pin2 for 50 store in w4 ount pin2 for 50 store in w5 ount pin2 for 50 store in w6 IF S3 0 and S2 0 GOSUB sampRED IF w4 gt thidRED then GOSUB blinkR IF w5 gt thidBLU then GOSUB blinkB w6 gt thldGRE then GOSUB blinkG IF S3 1 and S2 0 GOSUB sampBLU IF w4 lt thidRED then sampRED IF w4 lt thIdBLU then sampBLU IF w4 lt thldGRE then sampGRE IF S3 1 and S2 1 GOSUB sampGRE Figure 32 Overall Color detection program for PICAXE18X 5 4 Wireless Communication The Wireless Control Unit will consist of the Playstation 2 controller the controller interpreter and the transceivers It will be a two w
101. lling circuit converts the entire semiconductor contents of the array to a sequence of voltages which it samples digitizes and stores in some form of memory as a digital image This is older technology then CMOS and consumes much more energy than its counterpart Also the image acquisition is not as fast Though for our design purposes a CCD image sensor would have been adequate we admired the quality to cost ratio of CMOS and the fact that it is the cutting edge for low cost robotics imaging applications UNIT mm Figure Schematic of CM 26N from Spark Fun Electronics permission pending The CMOS image sensor used in this project the CM 26N outputs video at 640 x 480 pixels at 30 frames per second in an analog NTSC signal NTSC or National Television 51 System Committee is an analog video signal and most widely known as the television broadcast signal used in North America PAL Phase Alternating Line being the European equivalent The NTSC signal formation starts at red green and blue sensors and finally exists as a combination of two main components a Y signal and unique color information or difference signals Figure 20 shows a basic block diagram of the making of the NTSC signal The Y channel or luminance luma channel is a composite image having brightness and containing maximum detail It is obtained by simply adding the images seen by the red green and blue sens
102. ltage regulators linear and switching voltage regulators Linear Voltage Regulator Some of the components of the robot supply circuit are designed to operate with a constant voltage supply The supply voltage needed for their operation sometimes differ from the source supply voltage A voltage regulator provides this constant DC output voltage for the circuit and contains circuitry that will continuously hold this output voltage at the designed value regardless of changes in the load current or input voltage Therefore a linear regulator will supply a constant output voltage to its subsystems as long as the input voltage is within the operating range of the linear regulator Linear regulators operate by using a voltage controlled current source to force a fixed voltage to appear at the regulator output terminal This fixed voltage is supplied to our subsystems and remains constant The control circuitry basically monitors or senses the output voltage and adjusts the current source as required to maintain the output voltage at the desired value The limit of the current source determines the maximum load current the regulator can source and still maintain regulation As can be seen the basic linear regulator functional diagram the output voltage is controlled using a feedback loop which requires some type of compensation to assure loop stability The loop is important to ensure the continuous output of a steady voltage by the regulator Some of th
103. ly into the next position By having the robot only change directions on timed multiples of 5 then the amount of movement that the hexapod is doing should be minimized since it will either be undergoing zero movement or be in the transition point between two steps where one step will be finishing and the other step will be just beginning Since movement in every direction will consist of the same sequence of steps all that remains is to identify the sequence of steps that compose movement This problem will be simplified by considering the six legs as only three legs where the two legs that are directly across each other will move in parallel Whatever the front leg does the back leg will do The only difference will be that some of the final movements will be mirrored or inversed or else one can imagine that one leg would try to move forward while the other leg would try to move backward Therefore the same joint articulations will exist but they will all be mirrored Now since there will only in essence be three legs to worry about it seems natural to have a sequence of either 3 or 6 steps as a full sequence executing linear motion again with a time value of 5 which may be negative between each step for syncing purposes 112 Model Derivation In the previous subsection the analysis of the six legs was reduced to only three legs due to the properties of symmetry in movement a form of coupling the legs in order to reduce complexity Th
104. mary and secondary windings 69 When the switch is turned ON i e Mode 1 the input voltage is forced across the transformer primary which causes an increasing flow of current through it Here the diode will be turned OFF preventing the flow of current in the secondary windings Therefore the load current is supplied by the output capacitor alone thus discharging the capacitor When the switch is turned OFF i e Mode 2 the decreasing current flow in the primary causes the voltage at the dot end to swing positive At the same time the primary voltage is reflected to the secondary with the same polarity Here the diode is turned ON allowing the current to flow into both the load and the output capacitor Thus the capacitor is charging during the OFF time Below is a diagram of a flyback converter VOUT LOAD Figure 26 Diagram of a Flyback Converter Reprint permission granted through site www national com Boost Converter The Boost converter is basically used to provide an output voltage level that is higher than the input voltage level It can therefore be referred to as a Step up Converter The voltage levels here must also be of the same polarity Boost converters are essentially used in systems that convert smaller voltage levels to larger voltage levels of the same polarity for use in desired subsystems The boost converter operates very efficiently with very little power loss It also utilizes a transistor as a switch th
105. ming language for the device The main part of our design that was missing up until now was the threshold levels for each of the colors Up until now we had been testing with the same threshold just hoping to get any colored light detection In the finding of our thresholds we were getting indications of the correct color match for two different colors We used a sample time of 50 ms for collecting our color data as that was recommended in the user manual of the PICAXE color sensor The test procedure for finding the right threshold evolved into the following process Find a red blue or colored object Enter in a threshold for that color Hold it in front of the color sensor If nothing happened increase the threshold by 15 Hold another colored object in front of the sensor If nothing happened hold the final color object in front of the sensor If the indicator light went off for either of the two other colors increase the threshold by 50 TEO eae at oa Even before we started testing with the color sensor to calibrate the thresholds we wanted to ensure the syntax and behavior of our program was correct The PICAXE microcontroller software includes a simulation mode that allows program code to be simulated Each subroutine was tested to ensure that at no point there would be an unintentional infinite loop or no action being taken On the next page is a simulation screen shot of the program test code 104 Mu B 2
106. mium designs and can be extremely dangerous if mistreated Li ion chemistry is not safe as such and a Li ion cell requires several mandatory safety devices to be built in before it can be considered safe for use outside of a laboratory Below table 14 shows the different types of chemical compositions of lithium ion batteries Material Average Voltage Gravimetric Capacity LiCoO 3 7V 140mAh g LiMnO 4 0V 100mAh g LiFePO 3 3V 170mAh g Li2zFePO 4F 3 6V 115mAh g Table 14 Chemical compositions of Li ion batteries 63 Storing a lithium ion battery at the correct temperature makes all the difference in maintaining its storage capacity It is significantly advantageous to avoid storing the battery at 100 charge because a lithium ion battery stored at 40 charge will last longer particularly at high temperatures However if the battery is stored at a very low charge there is a risk of allowing the charge to drop below the battery s low voltage threshold resulting in an unrecoverable dead battery Once the charge has dropped below this level recharging the battery can be dangerous To prolong the shelf life of a lithium ion battery it is recommended to charge or discharge it to 40 and place it in a refrigerator Some lithium ion batteries will provide more energy when brought to room temperature Below table 15 shows the amount of permanent capacity loss that will occur after storage at given charge level and t
107. n angle while three legs at a similar complementary angle this setup not only provides the Drive subsystem with the most flexibility but the team also believes it looks most natural on the circular body chassis 77 5 2 Drive 5 2 1 Hardware There will not be much more design in terms of the hardware involved for the drive subsystem The 18 servomotors will be connected to the servomotor controller board and will then await input from the wireless communication control The vast majority of the design will go into the software portion of the drive system 5 3 1 Program Design Time and Step Definition The technique of inverse kinematics will be used to position the motors appropriately in order to create linear motion In order to avoid any difficulty in syncing the different steps together each step will occur a given value 6 after the previous step That is the time step will be uniform across all steps So if the walking sequence consists of 6 steps then the first step will occur and then the second step will occur afterwards The value 6 is in units of time such as milliseconds For the purpose of analysis 5 will be equal to zero 0 instantaneously after a step and will be negative before it Thus if it is necessary to begin a step before another step is finished then 6 will assume a negative value It seems to be a reasonable assumption to make right now that the time constant between steps whether it be negative ze
108. n figure 6 below 36 Figure 6 HexCrawler Hardware Kit www crustcrawler com reprinted w permission Since the rest of the project still contains much electrical and computer engineering work there was much deliberation in the group regarding purchasing this kit A couple of problems emerged however For one the electronics enclosure was fairly small and we did not believe that all necessary electronics would fit inside without significant effort This would limit the flexibility of our design further down the road Another deterrent was the fact that the chassis was initially built for only 2 degrees of freedom per leg More complicated dynamics could not be achieved by this mechanical structure unless certain adjustments were made Thus the team was already looking at having to modify the chassis something that was originally to be avoided Finally and perhaps most importantly the 299 price tag of the kit seemed a little too high Investigating other options especially buying the chassis legs and joints separately might yield an ultimate price tag that was significantly less than 299 and more in line with our budget Rectangular Body Chassis The next chassis that was investigated was a rectangular body chassis from www LynxMotion com During our overall research for products it was discovered that LynxMotion is one of the largest suppliers of robotic parts online Many other web sites are actually selling LynxMotion s prod
109. n was chosen due to the fact that it included very useful metal servomotor horns for every motor The price for every one of these horns is 3 25 and in striving to keep the mechanics of everything functioning properly through the arduous wear and tear it was deemed that this would be a good decision The group was already looking at purchasing metal horns separately so this special came at a good time Three of these packages would be bought for a total of 323 82 Figure 15 below shows a picture of the included tapped servomotor metal horns Figure 15 Metal servomotor horn from LynxMotion reprinted w permission 4 2 1 2 Servomotor controller Custom Made The first option looked at was for the team to build a servomotor controller board themselves However due to the fact that there will be 18 different servomotors to control independently as well as the fact that their control must be very closely synced together the idea was discouraged Instead other methods of servomotor control were pursued ones that could not only control multiple servomotors but control more than one of them within a fair amount of precision SSC 32 Controller This servomotor controller from LynxMotion has the capability of controlling up to 32 servomotors at once which was more than sufficient for our project It has luS resolution along with enabling what is called group moves such that multiple servomotors can be controlled simultaneously This
110. n when the robot is hunting for a color and it is off when the robot is on standby To summarize the wireless unit is to permit a convenient two way wireless communication between the robot and the user who will wirelessly control the robot in its movements and decisions 2 1 5 Power Depending on the projected use or application of a robot its design requires knowledge of programming remote sensing artificial intelligence and power systems A robot is device that can execute physical tasks automatically either by supervision or by programming it to follow a general set of guidelines through artificial intelligence The robot can be divided into three groups that allow it to move interact with its environment and be useful to others depending on its intended use The major groups include 1 The Brain a set of programs or a computer 2 Mechanical parts servos motors and legs 3 Sensors vision motion etc And all of these components require the use of power in order for them be functional The robot relies on a battery as its main power source All batteries in general only produce a single voltage level while the robot s subsystems require a diversity of voltage levels in order to function properly Therefore the power supply system must be designed to provide all the subsystems with the necessary power that they require Given that the main power supply of the robot is battery it consists of a combination of DC to DC conve
111. nce in source voltage and required voltage maybe small because they draw more current than the microcontroller and the sensor So to minimize the waste of power instead of using a voltage regulator we may use a switching voltage regulator to regulate the required voltage for the servos and motors Switching Voltage Regulator A switching regulator basically works by taking small chunks of energy bit by bit from the input voltage source and moving them to the output The switching regulator accomplishes this with the use of an electrical switch and a controller This electrical switch and controller combination regulates the rate at which energy is transferred to the output The transfer of energy from the input to the output is accompanied by losses during the transfer process These losses involved in moving the energy around are relatively small with the switching regulators In effect the efficiency of these regulators 68 is high in the order of 85 to 90 The regulator efficiency is normally less dependent on input voltage therefore they can power useful loads from higher voltage sources The switching regulators are rapidly gaining popularity and usage due to their high power conversion efficiency and increased design flexibility In using the switching regulator multiple output voltages of different polarities can be generated from a single input voltage This enables a single input voltage fed into the switching regulator to outp
112. nregulated power source and then have separate regulation systems for the supply circuit of the motor the digital supply and the analog supply circuitry And all the systems would have a common ground at the power source Having a common ground can be advantageous because the control signals from the different parts of the system can be sent just like any other signal But noise can also travel back up the control lines and corrupt the otherwise clean power Therefore this negates the use of a common ground in our system One more configuration is to have unregulated power sources for the major subsystem circuitries The motors tend to have a huge current draw on the system and this can cause voltage surges and ripples which are really bad for the electronic circuitry Therefore this configuration proposes the use of separate power source system for the motor circuitry and a separate power system for the electronic circuitry This configuration will make sure that the voltage distortions caused by the large draw by the motors does not affect the electronic sub circuits As a result the power supply would be able to eliminate the majority of the interferences and deliver a clean power to all the robot s subsystems and sub circuits For effective distribution of power to all of the robot s subsystems and sub circuits parts as seen in the table 1 above the power supply separates the supplies for part of the circuit that require precise voltage such as
113. nxMotion com reprinted w permission 4 1 3 Legs and Joints 4 1 3 1 Single Legs Although the team felt capable of being able to produce a chassis themselves legs are a different matter There was not enough time to do so It was agreed upon that the legs would be bought from a professional manufacturer Due to the way the mechanical system had been identified and outlined the team believed that obtaining legs and joints would be a separate process Thus this is the way research initially began Various vendors were researched in this area but it turns out that all of them were reselling merchandise from LynxMotion Therefore the group went straight to the source LynxMotion s website 40 It was decided that the first task would be to obtain a valid pair of legs and then decide how they would be connected to the chassis itself Two different types of legs were looked at initially The first one was the Robot Leg B Pair and would cost 19 95 It s size fit specifications at about 4 9 inches and its shipping weight was only 23 Ibs Figure 7 shown below is a picture of this model The servomotor shown in figure 10 is not included in the actual product Figure 10 Robot Leg B from www LynxMotion com reprinted w permission The second leg looked at also cost 19 95 and roughly had all of the same specifications as the previous leg It is called the Robot Leg A Pair at LynxMotion The group liked this model more since it was
114. o 10 loss factor to our battery voltage source to compensate for losses when the robot is operating is included The battery source for the electronics is 12V and the servomotors battery source voltage is 6V Each subsystem has its own voltage requirements therefore regulators are used accordingly to regulate the 12V battery source to satisfy the voltage required by each subsystem Efficiency cost losses and noises are considered in building the power supply of the robot Losses in any power supply system are inevitable However we can reduce the losses in the system to make sure that an adequate supply of power is delivered to every subsystem Wiring losses are reduced by making sure that just enough of wire runs between the voltage source and the target because the shorter the wire the smaller the loss in the wire The right wire size is also important in power transmission which is determined by the amount of current and voltage that is running through the wire Where to place the regulators are also very important Losses are unpreventable when the robot is operating so placing the regulators close to the voltage source causes less than desirable power supply to the robot s subsystem which causes that particular subsystem to malfunction Therefore the total source voltage is ran at its rated level and regulate it just before it is fed to the targeted subsystem so we guarantee that the desired voltage is delivered to its target Therefore the
115. o the controller The signal is mostly high and uses positive logic On the falling edge of the clock pin signal the interpreter or the console sends the data least significant bit first which the controller samples on the rising edge of the clock The maximum data rate is about 192000 bps PIN 3 N C Not connected 9 VOLTS The line to this pin is purple For the Playstation 1 version of the controller which was basically the first version this pin is inactive But for the Playstation 2 Dual Shock version which unlike its predecessor has a vibration mechanism a voltage of 9 V is to be applied to this pin in order to power the vibrator For our purpose this function is unnecessary so the pin is left disconnected PIN 4 GROUND PIN The wire is black or some shade of black This pin is to be grounded that is connected to the negative pole of the power supply 16 PIN 5 VCC PIN POWER SUPPLY Its line is red This pin is connected to the positive pole of a 5 volt power supply supplied by the console or the interpreter circuit This pin is also equipped with a 0 750A fuse PIN 6 ATT PIN ATTENTION This line is yellow Its role is to control and switch the state of the controller to one of two functions accept or ignore data from the Playstation 2 or the interpreter To enable the controller to accept data which happens through the COMMAND PIN or PIN 2 the ATT PIN must be set to low 0 before the first bit of data
116. on to reprint obtained from Microchip refer to A 3 Architecture Overview Features PC18F458 MCU Operating Frequency DC 40 MHz Internal Program Bytes 32K Memory of Single Word 16384 Instructions Data Memory Bytes 1536 Data EEPROM Memory Bytes 256 Interrupt Sources 21 T O Ports Ports A B C D E Timers 4 Capture Compare PWM modules 1 Enhanced Capture Compare PWM modules 1 Serial Communications MSSP CAN Addressable USART Parallel Communications Yes 10 bit Analog to Digital 8 input channels Analog Comparators 2 Analog Comparators VREF Output Yes Resets and Delays POR BOR RESET Instruction Stack Full Stack Underflow PWRT OST Programmable Low Voltage Detect Yes Programmable Brown out Reset Yes CAN Module Yes In Circuit Serial Programming ICSP Yes Instruction Set 75 instructions 26 Table 9 Some features of the PIC18F458 MCU Authorization to reprint obtained from Microchip refer to A 3 3 4 3 2 Atmel s AT90S2313 The AVR AT90S2313 is a low power CMOS 8 bit microcontroller based on Atmel s AVR RISC Reduced Instructions Set Computer architecture It has 32 general purpose working registers that are directly connected to the Arithmetic Logic Unit ALU allowing two independent registers to be accessed in one single instruction executed in one clock cycle Absolute Maximum Ratings Opera
117. on what it is used for When the input voltage is higher than the output voltage the regulator is referred to as a step down voltage regulator And accordingly when the input voltage is lower than the output voltage the regulator is referred to as a step up voltage regulator For our robot the source voltage will generally be higher than the required voltage of the different subsystems therefore we will implement the use of step down voltage regulators Figure 76 and Figure 77 below with their respective step down voltage regulators show two preliminary circuit diagrams with the voltage drops for the different electronics the microcontroller and the servo motors and figure 78 shows the final and complete circuit of the power suppl for the robot 118 Multimeter EE gt Multimeter x vt Figure 76 Circuit Diagram with the voltage drop for the camera and the microcontroller Multimeter x av AIP of Lx a G Figure 77 Circuit diagram with the voltage drop for the servo motors 119 R9 47kOhm_5 LED1 re Figure 78 Complete circuit with the respective voltage drops Section 9 Administrative Content 9 1 Budget The group is self sponsored with a projected amount of about 600 The cost of the project will be divided evenly among the group members During testing procedures and while building the robot components and parts may be damaged therefore the
118. opens rapidly the rated current is reached or slow blow time delay which will only open in the condition when the high current is sustained Therefore to protect the robot s servo motors and its power supply the robot would need a slow blow fuse but for this project it is not necessary since the robot uses low power To protect the wiring in the circuit it is necessary to rate the fuse to the gauge rating of the wire Below table 17 shows the gauge to current rating Gauge Current 12 41 13 35 14 32 15 28 16 22 17 19 28 16 19 14 20 11 21 9 22 7 23 4 7 24 3 5 25 2 7 26 22 27 1 7 28 1 4 29 1 2 30 86 31 7 Table 17 Gauge to current rating 76 Section 5 Design This section discusses the actual design of the hexapod robot The proposed method of implementation is shown here While the research section demonstrated the various possible options looked at while trying to find a given solution the design portion will discuss the solution chosen and expound upon how it will be brought into effect 5 1 Mechanics 5 1 1 Chassis There is not much left to design in terms of the body and camera chassis since they were bought prebuilt However this was exactly the team s goal to not have to design the chassis from scratch since once researched it was determined that the cost of doing so in terms of time was not warranted Section 6 will discuss how t
119. or Area IR Filter 3 8Lens Element 2 Lens Element 15tLens Element Lens Barrel Figure 17 Basic CMOS image sensor assembly http almanazir typepad com almanazir 2006 10 how_a_camera_ph html permission requested pending SON 7777 WW POTN Figure 18 CMOS Image Sensor with no lens assembly From http www mobiledia com news 57821 html permission requested CMOS image sensors utilize CMOS complimentary metal oxide semiconductor technology They are more generally named Active Pixel Sensor Imager and contain an array of pixel sensors Each pixel constitutes a photodetector and an active amplifier The standard CMOS image sensor photodetector consists of a JFET photogate or pinned photodiode a transfer gate reset gate M st selection gate M e and source follower readout transistor Msp as depicted in Figure 19 50 COL Figure 19 CMOS Image Sensor photo detector circuit in the public domain released by the author In contrast to CMOS there exists another type of image sensor the Charge Coupled Device CCD image sensor Instead of FET as a basic building block of pixels the CCD image sensor uses an array of capacitors The array is exposed to the image and a control circuit causes each capacitor to transfer its contents to its neighbor The last capacitor in the array transfers its charge into a charge amplifier which converts the charge into a voltage By doing this over and over the contro
120. or Urban up to 100 feet Outdoor line of sight up to 300 feet Transmit Power 1 mW 0 dBm Receiver Sensitivity 92 dBm Low Power TX Current 45 mA 3 3 V RX Current 50 mA 3 3 V Power Down Current lt 1l0uA Table 2 The Xbee RF module interfaces to a host device through a logic level serial port Through its serial port the module can communicate through a level translator to any serial device By default the Xbee RF module operates in Transparent Mode meaning it acts as a Serial line replacement All data received through the DI pin is queued up for RF transmission When RF data is received the data is sent out the DO pin The Xbee module is configured by either using Windows Hyper Terminal or Digi s X CTU available to download for free from their website To avoid using AT commands the latter is preferable as it presents the parameters of the module in a list which can be changed by a simple click of the mouse 3 4 3 BasicMicro s Atom Pro 28 M The BasicAtom Pro 28 M is the microcontroller chosen for this project It is used and recommended by many robotics enthusiasts mostly due to its large EEPROM and RAM 20 storage space necessary for the storage of constants and variables involved in calculations needed for the gait of the robot It is also due to the convenient peripheral functions of the Atom Pro 28 s I O pins This microcontroller is easier to use than most microcontroll
121. order to prevent putting too much strain on the motors and joints the chassis is to weigh no more than 34 of a pound by itself It should also not be wider than 3 feet at its widest point This means that if it is trapezoidal in nature its diagonals must not be longer than 3 feet These constraints are imposed now in order to facilitate the research phase they are based on the reasonable assumptions that if the chassis is too large or too heavy the motors necessary to move such a thing will either be too bulky or too expensive The chassis must provide some method of connection for the six legs and must allow the joints to exhibit their full range of motion without inhibition This means its perimeter must be sufficiently large such that all six legs can be connected through their hip joints and rotate as much as needed If these requirements are not met then motion will be impeded Another important specification is that the connection for all of the legs must be fully parallel with each other that is all leg connections must lay on the same two dimensional plane Although different sized legs could be used if this requirement were not met by meeting it the same geometry can be used for all six legs Note that this is in contrast to an actual hexapod in nature where only leg pairs are similar But by adhering to this spec building or obtaining the legs will become a substantially easier process The purpose of the body chassis is not only to pr
122. ore avoid exposing the battery to direct sunlight Short circuiting a lithium ion battery can cause it to ignite or explode therefore any attempt to open or modify the circuitry of the battery is dangerous and not recommended The battery contains safety devices that protect the cells inside from abuse and if damaged can cause the cells inside to ignite or explode Proper disposal is recommended Nickel Cadmium contains cadmium which is a toxic heavy metal and therefore requires special cares during disposal Since cadmium is heavy metal it can cause substantial pollution when land filled or incinerated because of this many countries now operate recycling programs to capture and reprocess Nickel Cadmium batteries Never short circuit a nickel cadmium battery because it may cause it to explode Never incinerate the battery because it can explode and release a toxic gas that contains cadmium Avoid dropping hitting or denting the battery because they may cause internal damage including short circuit of the cell Avoid rapid overcharging of the battery because this may cause leakage of the electrolyte out gassing or possibly even an explosion The safe temperature range for a nickel cadmium battery is between 20 C and 45 C Proper disposal is recommended Nickel Metal Hydride batteries are safer when charged with a charger that has a resettable fuse in series with the battery particularly of a bimetallic stripe This fuse will open if
123. ors When this is done we obtain a black and white image having brightness and detail The Y channel is a measure of what is redundant in a signal If we subtract this Y signal from the three red green blue image sensor signals we can obtain what information is unique NTSC chooses to subtract the Y signal from the red sensor to obtain an R Y red minus luminance signal and a B Y signal If Y is the total signal and we have the differences of R and Y and B and Y then the green signal can be determined Thus one signal can be thrown out and derived later if necessary VIDEO PROG MATRIX and Lai MMA DEGODER OOHRIECT KAY COLOR ERCOUEH NTSC COMPOSITE VIDEO Figure 20 The Making of an NTSC signal 4 3 1 1 Color Sensor There is another way of extracting analog image information and performing digital analysis on it That is via a color sensor Light shown on an object will reflect back with only the wavelengths of the colors present on the object surface in varying intensities Using this reflected light of certain wavelengths we can detect what color the object is by measuring some way the intensity of this light Color sensors made from simple optoelectronic devices that change their resistivity or gate voltage with incoming incident light of specific wavelengths colors Color sensor circuits can be made from photoresistors or phototransistors Photoresistors or light dependent resistors LDRs lower their resistanc
124. ose enough in resemblance to help illustrate the points being made in the text The instances where the images do not directly correspond to the project will be clearly identified 6 1 Mechanics and Drive 6 1 1 Leg and Motor Assembly If the legs are not properly built and the servomotors are not properly attached there is no hope for the Drive system to ever work no matter how good the code is Therefore detailed directions will be given on building each leg building the joints and attaching the motors All of these steps are actually done in unison since the motors must necessarily be integrated with the legs and joints in order to cause motion Pictures will be provided to illustrate every step since the details can get unwieldy Although these steps are given for the particular leg and joint models chosen many of these same general concepts can be applied to any model The essence of this step is to put the motors in such a position where they can actuate the joints to exhibit the three independent degrees of motion that are desired 93 6 1 1 1 Foot to Knee Assembly Push the servo through the leg as shown in Figure 43 This servo is responsible for knee motion Figure 43 Knee actuator placed in leg from www LynxMotion com reprinted w permission Push the spacer over the leg as shown in Figure 44 This will secure the motor and give it proper spacing Figure 44 Spacer inserted from www LynxMotion com reprinted w p
125. ot No more than one of these LEDs will be turned on simultaneously Only one of them can be on The LED display box will display one color at a time as the camera and the image processing unit will be programmed to detect one color at a time The fourth LED will be transparent it will emit white light It is on when the robot is hunting for a color and it is off when the robot is on standby To summarize the wireless unit is to permit a convenient two way wireless communication between the robot and the user who will wirelessly control the robot in its movements and decisions Section 8 4 Power The design of the robot s power supply is as efficiently as possible to allow the main battery source to run as long as possible before needing recharge The design of a power supply for a particular robot must take into account these things and along with the consideration of cost time and space The power supply of the robot meets the power requirement of every subsystem and allow for future project expansion if needed while the voltage regulators will efficiently maximize the robot s operating time Calculations and results show the efficiency of the regulators efficiency and voltage at rated load Discussions and research provided insight into need for appropriate component selections and placement ensuring a proper and successful implementation of a DC power converter and printed circuit board implementation 117 The robot relies on
126. ovide stability and structure but also to enable integration of the legs and joints into a single cohesive unit 10 3 1 1 2 Vision Unit Chasis A separate board will be added onto the body chassis for the color sensor in the Vision subsystem The color sensor will hang from the bottom of the robot By mounting it onto a separate chassis the electronic components necessary to drive it can be treated distinctly from the ones in the body chassis Not only will this save room in the final design but it also allows the construction of both chassis to be done independently This is a crucial factor for the project which is to be accomplished on a strict schedule This chassis is to be no greater than 8 inches or smaller than 4 inches along its widest part It must also leave at least 5 inches space between it and the body chassis in order to fit necessary components It is to weigh no more than a of a pound 3 1 2 Legs The legs must be capable of withstanding the chassis loads and must not bend or twist while walking Since the maximum load that the chassis will exert upon the legs is 1 pound and a reasonable assumption is that all of the electronics will not weigh more than 4 pounds the legs must be able to support at least 5 pounds The load will not be directly felt by each leg It will instead be distributed between each of the six legs The distributed load itself will be a function of the body chassis geometry and the connection point of
127. ple protocol for streaming data digitally from an uncompressed NTSC analog signal The BT 656 signal will allow simple read in to memory and analysis by our logic system Besides raw video data BT 656 contains status data to denote the end of active video EAV data and the start of active video SAV data Both EAV and SAV codes are comprised of a sequence of four bytes The first three bytes in the sequence constitute a fixed preamble FFh 00h 00h The fourth byte contains information about the field being transmitted Field 1 or Field 2 in an interlaced video signal the state of field blanking Vertical and the state of line blanking Horizontal These codes are embedded within the BT 656 video data stream thereby eliminating the need for additional timing signals HS YNC VSYNC BLANK to be included as part of the interface Figure 22 shows the standard BT 656 data stream EAV BLANKING SAY Active Video Data Figure 26 Standard ITU R BT 656 data stream format for a single horizontal line of digital video data 57 Active video data consists of 720 active samples of Y luminance and 360 samples each of Cp blue chrominance and C red chrominance After an SAV has been sent active video data is then sent in the following format Cbo YoCro Y Cb Y2Cr Y3 sieves cade Cb359 718Cr359 Y 719 Each set corresponding to one pixel Hence this is what will be outputted to the logic part of the imaging system the FPGA 4 3 3 FPGA
128. r Please note that the only thing the two units have in common are the name The PICAXE Color sensor is just the TAOS TSL230RD with a lens assembly on it to focus light The PICAXE18X has plenty of program and variable memory available for us as our program is relatively simple The PICAXE18X features a COUNT command that counts the number of square pulses input within a certain sample time Knowing this we designed our program to count the number of pulses and test it against a decided threshold found through testing to check if the correct color is found The user will be allowed to enter what color is desired by the two switches that will control the selection on the microcontroller and color sensor in unison The user will also be allowed to change the color to be detected via a set pause switch on the microcontroller When the set pause switch is high the color scanning 82 stops and the user selects a new color and then flips the switch to again begin color detection Input 2 analogue 2 LI Sertxd Serial Out LJ Input 1 analogue 1 Input 0 ana 0 infrared 1 2 Serial In Lj 3 Input 7 keyboard data Reset LJ 4 Input 6 keyboard clock ovOs5 V Output 0 LJ 6 Output 7 Output 1 i2c sda data LJ 7 Output 6 Output 2 L 8 Output 5 o Output 3 pwm output 3 4 Output 4 i2c scl clock Figure 31 PICAXE18X Microcontroller Pins The following pins of the PICAXE18X are used e Input 2 color sen
129. r requires the most Another significant difference between these linear regulator types is the Ground Pin Current The ground pin current is the current required by the 67 regulator when driving rated load currents This current is however undesirable because it must be supplied by the source but does not power the load It is therefore referred to as wasted current The standard regulator has the lowest ground pin current while the low dropout regulator has the highest An analysis of the different types of linear regulators based on their characteristics and our chosen application will reveal that the Low dropout LDO Linear regulator will be most suited for the AREN power supply system The LDO has very low dropout voltage which will ensure a steady power supply to our subsystems and the current draw from our systems is not nearly large enough make the ground pin current a concern Figure 24 below shows a basic diagram of a linear regulator Voltage Controlled Current Source VIN Sense Control Circuitry Figure 24 Linear Voltage Regulator Reprint permission granted through site www national com Linear voltage regulators can waste a lot of power by heat dissipation since the microcontroller and the sensors do not draw a lot of current using a voltage regulator to regulate their required voltage is not going to waste a lot of power But for the servos and motors the power wasted could be a lot even though the differe
130. r the original specs will be reworked or the parameters of motion will be reestablished Once the robot is able to faithfully move in any direction and transition from any direction to any other direction at different points in time without any fail or falter then the drive system will have been tested 7 4 Color Sensing 7 4 1 Color Sensor In the testing phase of the vision system there are 3 main variables the PICAXE color sensor the microcontroller and the object s surface which we are detecting The surface of the object will determine how much light is reflected back from the object And since this is what we are detecting and turning into square pulses this is very important to us We also needed to ensure that the white light from the LEDs formed a solid dot on the 103 object no dark space Dark space would mean no light is reflected to the lens For testing we decided to use colored poster board a reflective surface with very little color variation We first worked on just being able to detect any reflected light into the color sensor We found that the more the lens is screwed in the better it focuses light onto the internal TAOS TSL230RD This was a problem early on Once our test program was able to detect light a given threshold we moved on to getting different colors This required more extensive programming 7 4 2 Microcontroller Our microcontroller program was written in BASIC as this was the default program
131. rdware capable of making the robot move and then the necessary software to actuate the hardware First the hardware portion is researched and identified and the walking or gait algorithm is researched and identified 4 2 1 Hardware 4 2 1 1 Servomotors Since the position of each joint would have to be meaningfully manipulated by motors then the position of each motor must be easily manipulated as well Since servomotors already have a built in control system allowing the user to easily move its position they were the motors of choice for the hardware portion Therefore 18 servomotors would be bought where each of them would individually control each degree of freedom to the precision necessary The research question was then identifying the proper servomotors to do the job Since the team currently had a chassis and legs from LynxMotion which was the identical combo used in some of their robots it was natural to find out what type of servomotor in terms of torque and response speed was used in their robots The answer was a Hitec HS 475HB servomotor Figure 14 below demonstrates this motor 45 Figure 14 Hitec HS 475HB servomotor from LynxMotion com reprinted w permission Despite clear specifications regarding torque and weight regarding each servomotor the team was curious if there was any other reason that Hitec was used by LynxMotion An email to their representative and perusal of various online forums revealed that th
132. re the converter can be used as a step up or step down converter The input voltage is essentially inverted and the output voltage is of an opposite polarity to the input voltage The buck boost converter also operates very efficiently with very little power loss Similar to the other topologies it utilizes a transistor as a switch that forms two different operating modes for the converter The lower diagrams show the current flow paths for each of the modes when the switch is ON and when the switch is OFF When the switch is turned ON i e Mode 1 the input voltage is forced across the inductor causing an increasing current flow through it During the ON time the discharge of the output capacitor is the only source of load current Therefore the capacitor is discharging during the ON time When the switch is turned OFF i e Mode 2 the decreasing current flow in the inductor causes the diode to turn ON allowing the current in the inductor to supply both the output capacitor and the load Therefore the capacitor is charging during the OFF time A diagram of a buck boost converter is show in figure 29 below 72 SWITCH SWITCH OFF Figure 29 Diagrams of a Buck Boost Converter Reprint permission granted through site www national com Based on the characteristics and the analysis of the different types of switching voltage regulators using a buck converter would be better because the robot s voltage source will always be greater t
133. re is always the need to make sure that the voltage used is high enough so that the voltage drop cause by the wiring does not drop the supply voltage lower than the minimum voltage needed for the regulator to operate Once all the required voltages are delivered to every subsystem we can guarantee that the robot operates properly Since we are going to use a rechargeable battery it is necessary to have a charger which is going to be bought with the main battery source 90 Power System Noise Issues One of the biggest problems encountered when building a robot is noise In general robots will have digital electronics sensitive analog sensor processing electronics and power electronics to drive its motors and circuits The circuitry and digital electronics are constantly subjected to noise interferences and power surges from the motors and servos Analog signals can be corrupted with noise by either the digital or power electronics The standard and most efficient way to prevent noise in a power circuit is isolation Isolation ensures the separation of power electronic and motor subsystems from digital electronics subsystem The separation of the subsystems eliminates or reduce noise interference and improve the overall performance of the robot The power circuit could isolates the regulated power that is going to electronic subsystem circuitry from the power that is going to the servos and motors circuitry Another configuration is to have one u
134. ring the color sensor thus keeping out ambient light and ambient light 81 The size of the entire PICAXE Color Sensor module is about 1 in by 1 in 0 5 in which is well within our space considerations Two lines S3 and S2 are used for the color selection and will be connected in parallel with switches to inputs on the microcontroller When in operation the PICAXE Color sensor turns on whatever color filters are selected and then sends out square pulses at a frequency linear with the intensity of that light on the photodiodes Thus if there is green light getting through and the green filters are on then a very high frequency of square waves will be detected L S0 S1 OE 0V 00000 Sensor 00000 Connector V S3 S2 O OV Figure 30 PICAXE Color Sensor Pin connections V will be connected to 5 V S3 and S2 will be color selection L will be LED power OE is set to ground 0 V and 0 V are set to ground is for output and is connected to the microcontroller Above lists the pins for the PICAXE color sensor Since it has very low power consumption The color sensor will always remain on to avoid the added unnecessary step of a switch The user will be allowed to change colors after turning on the sensor by a pause set switch on the microcontroller 5 3 2 Microcontroller We chose the PICAXE18X microcontroller from Spark Fun Electronics to do our color processing The PICAXE18X is easily interfaced with the PICAXE Color senso
135. rive and Vision The first integration will be the communication and drive system Since the communication and drive systems were shown to be working independently this test will verify their capability to work together The communication system will simply send commands to the drive system and if the drive system continues to work as it was prior then the communication and drive integration will be successful If it is not working properly then before looking at both the drive and communication systems individually their integration will be analyzed This is because the previous tests give the team a fair amount of confidence that both systems are working properly in isolation thus the transition to having them both work in unison is what must be causing problems 7 7 Power Simulations Preliminary Circuit Simulations In order to better illustrate the voltage drops for the different subsystems across the power circuit of the robot preliminary simulations will be conducted While these simulations are not the complete simulations of the robot s power supply circuit they helped in the design of the best and efficient power supply circuit for the robot The color sensor in robot will need around 5 volts in order to operate the microcontroller will need 5 volts 108 and the servos each will need between 4 8 and 6 volts in order to function Figure 67 and Figure 68 below with their respective step down voltage regulators show two prelimina
136. ro or positive can stand to be uniform across all steps This fact may be altered of course as building progresses In order to further reduce complexity the same linear motion algorithm will be used in order to advance the robot in any direction Due to the fact that the robot has a circular chassis and that the legs will be connected with even spacing the robot will be rotationally invariant Therefore as long as the axes of linear movement are all equiangular the same sequence of steps can be used to cause linear movement regardless of the direction given to the robot from the radio controller Of course if a command is given to the robot in the middle of its sequence the walking algorithm must be able to either immediately reset to the beginning standard position or be able to transition smoothly into the next position By having the robot only change directions on timed multiples of 6 then the amount of movement that the hexapod is doing should be minimized since it will either be undergoing zero movement or be in the transition point between two steps where one step will be finishing and the other step will be just beginning Since movement in every direction will consist of the same sequence of steps all that remains is to identify the sequence of steps that compose movement This problem will be simplified by considering the six legs as only three legs where the two legs that are directly across each other will move in parallel Wh
137. rocedure for assembling an entire leg including the leg itself the joints and the motors The same process must be repeated six different times one time for each leg Once each leg is built the next step is to assemble the body chassis and connect the legs to the chassis which is the scope of the next two subsections 6 1 2 Chassis Assembly Since the body and the camera chassis already come prebuilt there is not much assembly involved The body chassis itself comes with instructions where all that is needed is to insert the given screws across from the top to the bottom of the body chassis and then fasten them tight Figure 57 below shows a view a yellow chassis not the same chassis color but identical in shape with the screws through it Figure 57 Body chassis to be fastened from LynxMotion reprinted w permission 100 If the necessary electronics will fit through the side of the chassis then they may be inserted that way If not they will need to be inserted prior to fastening the body chassis closed The camera chassis will simply go on top of the body chassis and consists of fastening the camera chassis onto the center of the body chassis This may done in any manner as long as it is secure Preferably two holes will be drilled into the body chassis and secured from the back end with appropriate nuts 6 1 3 Chassis and Leg Integration As seen above in Figure 57 the chassis already provides tapped holes for the integr
138. rters using linear or switching regulators which help regulate the different voltage level that each subsyste require For efficiency need and our budget design considerations is to be required in choosing the voltage regulators Since the battery also power the servos and motors which can cause noise therefore filtering and voltage isolation is advantageous for the robot s computer system Section 3 Specifications 3 1 Mechanics Detailed specifications are contained in this section which specify the requirements that certain mechanical components must meet Since the two primary objectives of this subsystem are to provide stability and mobility the chassis legs and joints will be analyzed separately The main function of the chassis and legs will be stability while the function of the joints will be mobility 3 1 1 Chassis 3 1 1 1 Body Chassis The chassis must be capable of housing all electronics material both safely and securely It must also provide adequate ventilation for them since we do not want valuable equipment to overheat The material itself is to be smooth in nature so adhesives can be used if needed for mounting As building gets under way it might be desirable to mount a battery pack or similar device with Velcro or tape and if the chassis surface were rough and coarse this might not be possible Besides its constituent material and geometry the weight and dimensions of the chassis are very important In
139. rtical Routing Channels I O Buffers 1 O Buffers A Array of Configurable Logic Blocks E T Horizontal Routing Channels 7 1 J I O Buffers Figure 27 Simplified XILINX FPGA architecture Diagram from Roger Meier permission pending Since the specifications require that the robot be able to detect a shape and a color the FPGA must be programmed to do so Several algorithms exist for doing so Using pseudo code examples the general algorithm can be shown 4 3 3 1 Microcontroller and Image Processing Algorithms Microcontrollers are small light weight in terms of computing power and are relatively simple design interfaces compared to FPGAs If we were to use a microcontroller for our image processing we would be able to program in the C language There are a myriad of microcontrollers available 59 For the camera we would need a microcontroller that could handle the 1 frame per second of 8 bit image data and process it before the next frame was captured One frame is equivalent to 640 rows of pixels by 480 rows of pixels or 307200 pixels There are 8 bits per pixel so 2457600 bits of data streaming is what the microcontroller would have to handle or 2400 bytes second and then do the processing Most microcontrollers at a speed of 8 MHz could handle this The only real limiting factor would be memory space to hold an image in a
140. runs off a 4MHz clock source with a divide by 64 prescale giving the timer a 16 microsecond interval which means the interrupt rate is expressed the following manner 1 Interval seconds To cR RATE hertz X PRESCALE Polling every 16 microseconds is too fast so to increase the interval a 16 bit timer counter register TCCR1 is used as a time keeper then a value of 0x0411 or 1041 is loaded into the timer compare register OCR1A This increases the time interval for polling to 16 microseconds x 1041 1 16 672 milliseconds The key reading interrupt used in the interpreter is based on the flowchart which is figure 40 below 87 Start of Interrupt po Lower ATT line AA Lower CLK line AA Place bit on COMM line y Hold 100 us Raise CLK v Read bit on DATA line v Hold 100 us a NO eee a Did 8bits _ gt YES Raise ATT line k Tast byte of transfer gt Exit interrupt Wait for ACK L Repeat steps for N E remaining bytes p4 Figure 40 Flowchart of the key reading interrupt 5 4 1 2 The PIC18F458 Microcontroller The PIC18F4580 is to receive and process the data from the robot s processing unit pertaining to vision and decisions made by the user through the use of the Playstation 2 controller Using the Playstation 2 controller the user will select a color to be searche
141. ry circuit diagrams with the voltage drops for two different electronics Also to ensure that the robot functions properly various tests are conducted since the project is divided into different subsystems each one of them have their own test procedures to make sure that the particular subsystem is working as it should be Also it will be easier that way because it would be a lot more complicated if the tests were to be conducted after the robot has been built of course the robot as a whole is tested but to make it easier every subsystem is tested first that way after integration if the robot does not operate properly it is easier to determine where the problem is and what should be done to correct it lt Multimeter i LAP asl ee ee Figure 67 Circuit Diagram with the voltage drop for the camera and the microcontroller LM 7805 Specifications e Output voltage 4 9V 5 1V e Output current 5mA 1A e Drop Out Voltage 2 0V LM 7809 Specifications e Output voltage 8 82V 9 16V e Output current 5mA 1A 109 e Drop out voltage 2 0V oz AIP of ail b Ce Figure 68 Circuit diagram with the voltage drop for the servo motors 7 8 Final Tests A thorough examination will be done confirming the proper functioning of all of the subsystems that make up the entire hexapod robot In essence it will be testing the vision drive and communication systems all
142. s created Figure 73 shows this block diagram The controller will await an input it will then decode the appropriate direction and decide which legs will be moved and then goes through the sequence of moving each leg with a time step in between each Afterwards it again waits for an input signal to determine what its next direction will be 113 Wait for Input Decode Direction Front Leg Back Front Leg Sequence Mirror Sequence Time step Vv AA Back Alternate Alternate Side Leg Side Leg Mirror Sequence s equence Time step y y Side Leg Back Side Leg Sequence Mirror Sequence Reset internal gt o servo positions Figure 73 Block diagram of gait algorithm 114 Section 8 2 Color Sensing The PICAXE Color Sensor module a combination TAOS TSL230RD light to frequency converter and lens assembly and PICAXE18X microcontroller will be our color sensing unit The color sensor module illuminates the object with white light from 2 LEDs The reflected light enters the lens and hits the TAOS TSL203RD If the correct color filter is selected square pulses will be generated If the number of square pulses in the 50 ms sample time meets the threshold for that selected color than an indicator LED will light 3 2 Key Space Key Space i 10kOh_5 R2 Ri 47kOhm_5 VOC sy
143. s it contained plenty of room to store necessary electronics and met necessary weight and size specifications In fact this chassis was a bit smaller and weighed a bit less with a shipping weight of 66 lbs A circular chassis is shown in figure 8 below 38 Figure 8 Hexapod Circular Chassis from www LynxMotion com reprinted w permission The circular chassis cost 39 95 which was ten dollars cheaper than the rectangular chassis Since this chassis met all necessary specifications was lighter smaller and less expensive than the rectangular chassis the team was very interested in it We also thought the cool black color looked better Therefore the team opted to choose the circular body chassis from LynxMotion However another important reason for this choice was that it would enable the hexapod to have great mobility since it could move in any direction at once If a rectangular chassis were chosen the robot would have to rotate before changing its heading With a circular chassis the robot can choose to move in any direction at any point in time sans rotation 4 1 2 Vision Unit Chassis 4 1 2 1 Handmade Custom Although it was decided that constructing the body chassis internally was not the best way to go about doing things it was again considered for the vision unit chassis The vision unit chassis would be much smaller and would not be nearly as intricate as the body chassis It was decided though that professional buildin
144. s of regulators and examine their respective use and efficiency The comparason between the disadvantages and advantages of both types of regulators in order to choose the regulator type that satisfies our different specifications and meets our efficiency and cost requirements The calculation of the maximum power requirements for each individual subsystem of the robot is done which are voltage and current required by each The subsystem and their power requirements are listed in table 19 below 89 Blocks Voltage V Current mA Maximum Power W Control Unit Micro Controller 2 0 5 5 25 138 Vision Unit Color sensor 5 30 15 Micro Controller 2 0 5 5 25 138 Remote Sensing Unit Micro Controller 2 0 5 5 25 1375 Receivers 4 9 5 80 140 719 Transmetters 4 9 5 80 140 719 Mechanical Unit Servocontroller 6 9 31 279 Servo Motors 18 4 8 6 0 1100 6 6 Table 19 Subsystems required voltage current and power The maximum power requirement of each subsystem is classified in the table above and so is the overall maximum power requirement of the robot The table helps decide the battery source voltage and the type of regulator that is going to be needed to reduce the source voltage to the required voltage of each subsystem To decide the voltage of the battery source the power supply also includes the losses in the lines losses cause by heat and interferences Between a 5 t
145. s used in the circuit In a circuit that has noise sometimes currents change directions if the current in the circuit flow in the wrong direction the microcontroller in the robot may be damaged therefore to ensure that the current in the circuit will flow in one direction the circuit uses an LED as a power indicator and also to keep current flow in one direction Also to conserve energy and to control when the robot is operating a switch is used There many different types of switches but the robot has a single pole single throw toggle switch to turn it OFF and ON it is simple and easier to use than the other switches Capacitors Electrolytic Capacitor For the quick release energy storage in the robot an electrolytic capacitor is used because electrolytic capacitors have a large capacitance per unit volume so they are really helpful in fairly high current electrical circuits And they are relatively cheap and are readily available Polyester Film Capacitor To reduce the high frequency noise in the circuit the power supply use a metalized polyester film capacitor they have low tolerance which is adequate for a lot of applications And also the this type of capacitor are temperature stable cheap which is good for our budget since we want to spend the least money possible and they are readily available 75 Types of Fuse Fuses according to the time they require to respond to a high current are characterize as fast blow which
146. sor input Input 1 Set switch Input 7 S3 Input 6 S2 Output 7 6 5 Red Green Blue LEDs The PICAXE18X along with the switches and indicator LEDs will be housed on top of the robot on a printed circuit board Electrical data for the PICAXE18X is below It meets the specifications just fine 83 Absolute Maximum Ratings Pimentel a ermal na OR isi inc essai cnc cinta SE OO A a SI TN ce gece neo 65 C to 150 C Voltage on any pin with respect to VSS except VDD MCLR and I E E 0 3V to VOD 0 3V bce et Race cc ee ee E 0 3V to 5 5V Voltage on MCLR with respect to VSS Note 2 ec ecceesceccecceeeeecceesueeeeeceesnesoeesecseeesueseeesneeeeeeeeceeees OV to 13 25V nara rae A ein mere ee OV to 8 5V Thi p aa I i a as 1 0W Maximum current out Of VSS pin 2 eeeeeeeeece en seceeeeeneenseceeeenneensneecenenecsnnneesnensesnneeesneneesnneeesteneesneeeeneneee 300 mA a ene eee eee Le Pee PONE Rea Ea ne ene Ee EE 250 mA kogni usap ansent BK OA lt 8 ar V D Vinnan 20 mA Output clamp current IOK VO lt 0 or VO gt VDD Sani a sae Woy eet ED a ieee Mexia output cavent squsced by any UO pin NTT HMA ee ee Table 18 Electrical Characteristics of PICAXE18X 5 3 2 Microcontroller and Color Processing Algorithms To determine what color is being sensed we really do not have any information directly from the object All we have is a square pulse train at a certain frequency Each surface reflects light back a
147. susceptible to power surges and noise interferences and often require large amounts of currents Therefore the design of the power supply can efficiently handle interferences from the different sources while delivering efficiently the amount of power required by the different subsystems of the robot After researching the different ways of building the robot s power circuit and voltage conversions the best and most efficient way to build the power system that delivers power and regulate the robot s voltages efficiently is chosen The robot is able to run for at least one hour continuously Since this is a low cost budget rechargeable batteries are used to minimize the project s cost The overall power supply of the robot combines low cost and efficiency to give us the best functional robot possible The design of the robot s power supply is as efficient as possible to allow the main battery source to run as long as possible before needing recharge The design of a power supply for a particular robot takes into account these things and along with the consideration of cost time and space The power supply of the robot meets the power requirement of every subsystem and allow for future project expansion if needed while the voltage regulators efficiently maximize the robot s operating time Calculations and results show the efficiency of the regulators and voltage at rated load Discussions and research provided insight into need for appropri
148. t it met specifications while being sufficiently rugged would require a disproportionate amount of time and effort It was decided that a chassis would either be custom built by a company or ordered from a robotics vendor 4 1 1 2 Professional Custom By searching online and asking other individuals who had a bit more experience two different companies emerged as potential contractors for building our chassis The two companies were Pololu Robotics amp Electronics at www customlasercutting com and SuperDroid Robots at www superdroidrobots com The first company looked at was Pololu Robotics amp Electronics Although they only provided custom laser cutting they would also provide the material to be cut if it was 35 needed This was a great fact since we did not want to spend the time in actually obtaining the material and then shipping it to them They specifically stated that they neither stocked nor cut metal but did stock and cut plastics The thickest sheet they could cut was half an inch which was fine The laser cutting would cost 4 00 per ft and so it might prove to be a little more than we hoped to spend on a body chassis A significant problem with this company respective to our needs was that they would only cut the materials for us we would still be responsible for assembling it and providing adequate enclosure for the electronics In other words while we needed a three dimensional structure they could only adequat
149. t once it seems like a hobbled human being The side leg should raise its vertical hip position move its hip position horizontally extend its knee and then lower its vertical hip position This will be a side step forward The front leg should then raise its vertical hip position maintain its horizontal hip position since it is in the direction of movement and extend its knee This will be a step forward and this step will return the side knee joint to its proper position Then the alternate side leg will mirror the sequence of the side leg This is the model derivation concept where the actual angular values and consequently servomotor positions will be dependent upon the length of the legs themselves 79 5 2 2 3 Program Execution Wait for Input i Decode Direction Front Leg Back Front Leg Sequence Mirror Sequence Time step y v Back Alternate Alternate Side Leg Side Leg Mirror Sequence Sequence Time step y y Side Leg Back Side Leg Sequence Mirror Sequence Reset internal servo positions Figure 30 Block diagram of gait algorithm 80 In order to better illustrate the execution of the gait algorithm a block diagram was created Figure 30 shows this block diagram The controller will await an input it will then decode the appropriate direction and decide which legs will be mov
150. t voltage 0 4 V High level input current 5 microamperes Low level input current 5 micro amperes Table 13 Some Electrical Characteristics of the TAOS TSL230RD The TAOS TSL230RD is available on a printed circuit board with pin connectors for its input outputs and a lens assembly from Spark Fun Electronics for 44 95 The lens assembly would be very helpful in keeping out ambient light and infrared light Also the board it comes on would be very easy to attach to another board and also for testing purposes It also outputs data continuously in the form of square pulses so there is no need to program timing considerations into the image processing unit 4 3 1 1 2 Avago ADJD S371 QR999 The color sensor by Avago is also a light to frequency generator similar to the TAOS color sensor but with a bit more options and control The Avago light to frequency generator allows the user to select gain levels of output signals for individual color channels as well as put the device in a sleep or inactive mode The Avago device also allows for an external oscillator clock This would be useful if we were using an external memory device as would be needed would the Avago device since it outputs a large amount of data serially 54 peewee eenne LED ANODE DIGITAL OUTPUT Wa Figure 22 Functional Block Diagram of the Avago ADJD S371 QR999 The Avago is also very very small which is great for space considerations but too small may make it
151. teract as it would with a Playstation 2 console It would be preferable to use a Playstation 1 controller as to follow the documentation by the letter but only Playstation 2 DualShock 2 was on the market After a little more research though it has been noticed that the Playstation 2 is not even close to be barely different from the Playstation 1 controller The Microcontroller Many microcontrollers on the market right now can be used to interpret the data from the controller for the RF module and the brain of the robot So far it has been discovered that two of them have been used to handle the task of interacting with the controller Motorola s MC68HC11 MCU and Atmel s AT90S82313 The most recent documentation found involves the latter microcontroller was more recent so an Interpreter built around the AVR AT90S2313 received more consideration especially due to the fact that Atmel s microcontrollers are more commonly used in gaming electronics But after some research the Atom Pro 28 M was discovered and due to its extreme simplicity and to some of its convenient features in comparison to the microcontrollers mentioned previously was chosen for this project definitively The Transceiver A two way traffic of data of significant rate between the controller and the robot is needed for good control so two RF transceivers were necessary First Atmel s products were considered due to the high frequency of their products being used
152. th of these transceivers come with either an integral antenna or an MMCX connector for antenna without being included on development boards Of course it comes out to be more expensive than the previous chips but much cheaper than the development boards Linx Technologies RF modules were next considered Their price and their plug and play feature caught our attention The only downside was the fact that they were mostly surface mount devices PCB boards were necessary to even test them and antennas were to be installed PCBs were designed and built but their mysterious less than sastifying and inconsistent performance forced us to look for other solutions Observing another group using Xbee modules caused us to adopt them as well Though not as straightforward as Linx Technologies RF modules an antenna is already installed no PCB board was required for testing and they were more definitely more reliable and consistent in performance than the Linx Technologies RF modules 4 5 Power Types of Batteries In designing the robot s power supply one of the most important things to take into consideration is the battery source amp hour rating because it tells the maximum power the battery can supply and for how long it can supply that power This also decide how long the robot can run for Therefore rechargeable batteries are 62sed to power the robot which will save the cost of buying a lot battery Rechargeable Batteries Since we w
153. ting Temperature 55 C to 125 C Storage Temperature 65 C to 150 C Voltage on any pin except RESET with respect to ground 1 0V to VCC 0 5V Voltage on RESET with respect to ground 1 0V to 13 0V Maximum Operating Voltage 6 6V DC Current per I O pin 40 0 mA DC Current VCC and GND pins 40 0 mA Table 10 Absolute Maximum Ratings of the AT90S2313 microcontroller Authorization to reprint obtained from Atmel refer to A 4 DC Characteristics TA 40 C to 85 C VCC 2 7V to 6 0V Symbol Parameter Condition Min Typ Max Units Vit Input Low Voltage Except XTAL1 0 5 0 3Vcc V Vii Input Low Voltage XTALI1 0 5 0 1 V Vin Input High Voltage Except XTAL1 RESET 0 6Vcc Voect0 5 V Vien Input High Voltage XTAL 1 0 7Vcc Vect0 5 V Vim Input High Voltage RESET 0 85Vcc Vect0 5 V VoL Output Low Voltage Io 20 mA Vcc 5V 0 6 V Ports B D Io 10 mA Vcc 3V 0 5 V 27 Vou Output High Voltage Ion 3 MA Vcc 5V 4 3 V Ports B D lon 1 5 mA Vec 3V 2 3 V In Input Leakage Vcc 6V pin low 1 5 uA Current I O pin absolute value Im Input Leakage Vcc 6V pin high 980 nA Current I O pin absolute value RRST Reset Pull up 100 500 KQ Resistor Ryo VO Pin Pull Up 35 120 KQ Resistor Tec Power Supply Active Mode Vcc 3V 3 0 mA Current 4MHz 1 0 mA Idle Mo
154. to be targeted Playstation Connector Pin Descriptions Oftentimes the Playstation 2 controller is equipped with a male connector pinouts matching the female port of the Playstation 2 console rare if not nonexistent are the controllers that come equipped with female no pinouts connectors The connector is composed of nine pins and a small square metal plate at the bottom of the connector usually referred to as the tenth pin that is connected to the shielding of the controller s cable Through these pins the controller and the console in our case the interface circuit send to and receive from each other serial data using the TTL or digital signal format 101110001 The pins are labeled as shown in Figure 2 PIN 1 DATA PIN The wire to this pin is brown Through it the controller and the Playstation 2 console communicate in a one way traffic where the controller sends serial data to the Playstation 2 or the interpreter circuit Data are sent by byte least significant bit first the lower bits of a data byte are output first on the falling edge of the clock pin signal while the console or the interpreter reads the data on the rising edge of the clock It is usually high and uses positive logic 1 5 volts 0 0 volts The maximum traffic rate is about 192000 bps PIN 2 COMMAND PIN Its wire is orange It allows one way communication between the controller and the console where the console sends data serially t
155. together If the robot is still receiving signals from the communication system and moving accordingly then the drive system is working However the vision system must also be working concurrently and autonomously Therefore the robot will be made to walk around in an environment with objects of the colors specified red green and blue and depending on what user mode is an LED will turn on 110 Section 8 Design Summary Section 8 1 Mechanics and Drive 8 1 1 Legs and Body The leg packages to be obtained are shown in Figure 69 There will be 6 of these legs They will all be connected to the body chassis shown in Figure 70 oe aE Figure 69 Leg package left from LynxMotion reprinted w permission Figure 70 Body chassis right from LynxMotion reprintd w permission 8 1 2 Drive hardware There will be 18 servomotors for every joint and they will be Hitec 475HB servomotors They will be controlled using the SSC 32 servomotor controller An Hitec 475HB servomotor is shown in Figure 71 and a SSC 32 servomotor controller is shown in Figure 72 Figure 71 Hitec 475HB left from LynxMotion reprinted w permission Figure 72 SSC 32 right from LynxMotion reprinted w permission 111 8 1 3 Drive software The technique of inverse kinematics will be used to position the motors appropriately in order to create linear motion In order to avoid any difficulty in syncing the different steps together e
156. too difficult for testing and building The dimensions of the Avago unit are 3 9 x 4 5 x 1 8 mm Figure 23 Avago ADJD S371 QR999 The Avago device has a timed data transfer so the image processor whether it be the microcontroller or FPGA must be programmed to accept data at the start sequence The master initiates data transfer after a START condition Data is transferred in bits with the master generating one clock pulse for each bit sent For a data bit to be valid the SDA data line must be stable during the HIGH period of the SCL clock line Only during the LOW period of the SCL clock line can the SDA data line change state to either HIGH or LOW A complete data transfer is 8 bits long or 1 byte Each byte is sent most significant 55 bit MSB first followed by an acknowledge bit or not acknowledge bit Each data transfer can send an unlimited number of bytes depending on the data format cy af se noe HY TOIT HT Yo j Pi d inacil j Seccad i sit Hh mM m wA fei a a B a te i ry fi fai Ts 9 SCL i A 1 2 o j 8 9 o 1 Ly Ls or Sr LP START or repeated STOP or repeated START CONDITION START CONDITION Figure 24 Avago ADJD S371 QR999 data stream The Avago ADJD S371 QR999 color sensor is available from Spark Fun Electronics for 19 95 already pre soldered onto a printed circuit board Recapping of the prices and vitals of our image color sensor uni
157. ts is shown in table Sensor Unit Difficulty of Timing Price Size Power Interfacing to Considerations Consumption Image Needed processor NTSCCamera High Yes 29 95 2 in 1OmW CMOS 26N x 2in x 1l in Photoresistor Low No 20 00 4 in Unknown Circuit x 4in Phototransistor Low No 20 00 4 in Unknown Circuit x 4 in TAOS Low No 44 95 1 in 5mW TSL230RD x lin Avago ADJD High Yes 19 95 5 S 371 QR999 2 in microamp 5 x 2in microW Table 14 Comparison of Color Sensor Solutions 56 4 3 2 Video Decoder The video decoder would only be needed for the camera This section describes that component If a color sensor circuit is used there would be no need of course for the video decoder Once an image is acquired in the form of an analog NTSC signal in order for any logical and computational operations to be done on it it must be in a digital format A video decoder does just this It is a subset of analog to digital converters that allows an analog signal to ultimately be in a format that can be read analyzed and or manipulated by a computer There are a variety of digital formats that a video decoder can output Figure 21 shows a basic NTSC video decoder block diagram NTSC OOMEDSITE VIDE COLOR DIFFERENCE DECODER COLOA BURST i MHz cac Figure 25 Basic NTSC decoding system One of particular interest is the ITU BT 656 video signal format It is a sim
158. ucts This was a market trend noticed and was quickly posted online to the entire group so others could better focus their searches It turns out that LynxMotion specializes in hexapod robots They sell many premade robots for several hundred dollars and also sell kits for individuals who want to build the robots themselves However they sell kit pieces individually as well This meant that the chassis sold in their hexapod kits were available for individual sale The first hexapod 37 chassis investigated was their rectangular body chassis This chassis is shown in figure 7 below Figure 7 Hexapod Rectangular Chassis from www LynxMotion com reprinted w permission The total shipping weight of the chassis is 73 lbs therefore it met the weight spec Its length was a little over 2 feet so it also met the length specification The chassis was also desirable due to it being constructed from aluminum enabling adhesion and the fact that it had plenty of space for enclosing electronics All of the leg connections also lay on the same two dimensional plane as was specified The price of the chassis was 49 95 which was considered reasonable It certainly seemed like it was the beginning of a much better bargain compared to the 299 price tag on the HexCrawler Kit However it admittedly did not look nearly as cool Circular Body Chassis LynxMotion also vends a circular body chassis for hexapod robots Similar to the rectangular chassi
159. ut various output voltages These outputs can be used to power several subsystems and sub circuits which increase the flexibility and efficiency of the switching regulator Below figure 25 shows a basic diagram of a switching voltage regulator Figure 25 Switching Voltage Regulator Reprint permission granted through site www national com There are many switching regulators the most commonly used ones are 1 The Flyback Converter 2 The Boost Converter 3 The Buck Converter 4 The Buck Boost Converter Flyback Converter The Flyback converter is a very unique converter with diverse utilities It produces an output voltage that is less than or greater than the input voltage This converter is capable of generating an output voltage whose voltage level is less than the input level or it can produce an output voltage whose voltage level is greater than the input level Therefore this converter can be used in applications that desire either a voltage step up or a voltage step down It is also capable of producing multiple outputs Consequently its output voltage can be supplied to several subsystems simultaneously The fly back regulator is therefore the most versatile of all the regulators The lower diagrams show the current flow paths for each of the modes when the switch is ON and when the switch is OFF The most important feature of the fly back regulator is the transformer phasing as shown in figure 26 below by the dots on the pri
160. ven though they will be part of the same unit and soldered on the same board One of them is to interpret the data from the Playstation 2 controller The relationship between this microcontroller and the Playstation 2 controller will be the same as that between the Playstation 2 console and the controller hence the microcontroller is to emulate the Playstation 2 console It will receive the data from the controller which transmits it in serial format then process it and spit it out in parallel format to the transceiver which will be on the same board The other microcontroller is to collect and organize the data sent out by the robot through the transceivers This set of data is composed of data from the image processing unit of the robot and data concerning some decisions made by the user through the use of the Playstation 2 controller After processing the data the microcontroller will be programmed to display it explicitly to the user through a LED display thereby informing the user on the status of the robot Evidently two transceivers will be used in the wireless unit of the system allowing a two way data transfer between the mobile unit and the robot one let it be labeled Transceiver 1 on the mobile unit which consists of the Playstation 2 controller and the two microcontrollers covered above the other labeled Transceiver 2 on the robot In sending mode Transceiver Icollects and transmits to Transceiver 2 the parallel data supplie
161. waves is outputted These are known as light to frequency generators One really useful thing we also found in our research is that these light to frequency generators can be purchased with light filters on them already allowing only red green or blue light to reach the optoelectronic devices We found two major and widely used light to frequency generators commercially available 1 the TAOS TSL230RD and 2 the Avago ADJD S371 QR999 4 3 1 1 1 TAOS TSL230RD Color Sensor The TAOS TSL230RD is a light to frequency generator integrated circuit It is composed of an array of 64 photodiodes 16 with red color light filters 16 with green color light filters 16 with blue color light filters and 16 with clear filters The specific filters are selectable with two digital inputs The truth table for the color selection is shown below Filter S3 S2 Red L L Green H H Blue H L Clear L H Table 12 Truth Table for Color Selection on the TAOS TSL230RD The square pulses are outputted from the IC at a frequency linear to the intensity of light 53 Figure 21 Functional Block Diagram of the TAOS TSL230RD The TAOS TSL230RD is a very low power device and will our power as well as our weight specifications as indicated in the table below CHARACTERISTIC UNIT Supply voltage 5V High level input voltage 5 V Low level input voltage 0 0 8 V High level output voltage 4 5V Low level outpu
162. what type of feedback mechanisms will be employed to most efficiently solve this problem In order to provide the necessary torque to rotate the mechanical components responsible for leg movement or the joints motors will be used The 18 degrees of freedom can then be defined as 18 distinct joints and 3 joints will exist on every leg Each triple pair of motors will then rotate the joints in a particular fashion such that the leg itself moves along a given arc of motion With the combined effort of the six legs that is the combined six arcs of motion the robot will then be able to move in any path linearly that is the rotational motion will be converted to linear motion An algorithm must be created to properly drive the legs and a method to actually make the motors follow the given algorithm must also be created Thus proper control of the legs will rely on not only writing proper software but on being able to build the necessary hardware that can command the motors to execute the software in sync This will be a significant difficulty since all 18 motors must be controlled at once The main objective of this subsystem is to provide a method by which to linearly translate the position of the robot to move it It must provide a fluid and somewhat aesthetic movement that does not falter or crash when the robot starts stops or changes directions Which directions the robot will move in what joints will provide movement gait speed and other
163. which generates baud rates according to the following equation fex BAUD _ s 16 UBRR 1 BAUD Baud Rate fcx Crystal Clock frequency UBRR Contents of the UART Baud Rate register UBRR 0 255 The UBRR register is an 8 bit read write register which specifies the UART Baud Rate according to the formula above SRAM 224 Data Memory locations address the Register file V O Memory and the data SRAM The first 96 locations address the Register File I O Memory and the next 128 locations address the data SRAM The five different addressing modes for the data memory cover Direct Indirect with Displacement Indirect Indirect with Pre Decrement and Indirect with Post Increment In the register file registers R26 to R31 feature the indirect addressing pointer registers The Direct addressing reaches the entire data address space The Indirect with Displacement mode features 63 address locations reach from the base address given by the Y and Z registers When using register indirect addressing modes with automatic pre decrement and post increment the address registers X Y and Z are used and decremented and incremented The 32 general purpose working registers 64 I O registers and the 128 bytes of data SRAM in the AT90S2313 are all directly accessible through all these addressing modes T O All AT90S2313 I O and peripherals are placed in the I O space The I O locations are accessed by the IN and OUT instructions trans
164. xact product picture for example http www_crustcrawler com products hex pages hex3_htm and use it to explain what we are referring to Thank you very much in advance Sincerely Roberto Miguez Reply gt Forward webmaster at CrustCrawler to me show details Nov 24 2 days ago 5 Reply Hello Roberto Sure grab whatever images you need By the way the link in your email points to http www lynxmotion com images Products Full hbkrblk jpq Good luck on your project Best Regards Mike Gebhard CrustCrawler Inc Figure 17 Permission from www crustcrawler com to use any of their images 123 A 2 LynxMotion Products Permission Regarding pictures on your website tnbox X Y Roberto Miguez to sales show details Nov 23 2 days ago 4 Reply Dear Sales Staff For our Senior Design Project at the University of Central Florida we will be using some of your products Since we are building a hexapod robot many of your products are exactly what we need Our documentation needs us to show where we obtained our products from Would it be alright if we use some of the pictures on your website to better explain the products A picture really is worth a thousand words The immediate caption below the picture would mention your company and website and there would also be mention of the company at the end of our documentation All we want to do is take the exact product picture for example http www lynxmotion

Senior Design II Documentation - University of Central Florida

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