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1. ND NAN PO Po Rectangular aluminum profile wheel legs Width 80mm Depth 40mm Height Thickness 4mm Planes Steel sheets Thickness 0 5mm Width Height Description Batteries The battery pack includes four FGH 20902 High rate 12V 9Ah batteries Battery pack DC output 24V 18Ah Charging Recharge the battery pack is very easy as shown by the following steps 1 Ensure that the robot and the MacMini are turned off 2 Unplug the robot power plug from the battery pack power plug 3 Plug the charger s plug in the battery pack power plug 4 Plug the charger to the power grid 5 The charger s LEDs indicates the charging status 6 When the green LED lights the battery pack is fully charged 7 Unplug the charger from the power grid 8 Unplug the charger s plug from the battery pack power plug 9 Ensure that the robot s power switches are turned off 10 Plug the robot power plug in the battery pack power plug Electrical schema The following electrical schema shows the power supply wires in the robot We can see that the ground wire coming from the batteries goes to the ground stabilizer This stabilizer is a piece of copper from which departs the ground wires for all electrical components On the 24V line we find a fuse and the main power switch which is highly recommended to be turned off if the robot is not in use Inside the electronic case there are 3 electronic components2. e ERROR 2 bad data This error is shown when we indicate in the command a not valid data i e numbers in wrong format e ERROR 7 bad command This error is shown when we indicate a wrong command i e EEPROM write request without associated value e ERROR 99 unknown command This error is shown when we indicate a command that does not exist Auto tuning parameters This command allows to get set automatically some important robot parameters such as MAX encoder ticks its syntax is t lt DEVICE gt lt DEVICE gt is the device we want to set parameters automatically This feature is very important because if we change the motors or encoders we can retrieve these parameters automatically The most important parameter retrieved is MAX encoder ticks i e actually NUM encoder ticks at the MAX speed for both the motors When these parameters have been calculated they are automatically written in the EEPROM the mnemonic strings are maxtcO or maxtcl Warning This command set the motor to its MAX speed Before start auto tuning if you are testing traction motor you should raise the robot so it can t start without control at its MAX speed If you are testing rotation motor pay attention no one finds near the robot The test lasts about 5 second
3. e The 24V to 18V switching step down power converter board which powers the MacMini e The 24V to 5V switching step down power converter board which powers the IRABoard e The IRABoard v1 1 for details see the electronic section MOTORO MOTOR 1 MAIN POWER SWITCH Battery pack Electronic case MacMini REMOTE STOP Electronics The electronic case contains the all the electrical and electronic components of the RoboCom There are 3 components DC DC 24V to 18V board We implemented the evaluation board of the ST L4970A 10A step down switching regulator This board carries two big capacitors 3300 uF which grants clean output even in case of perturbations on the power line The ST L4970A component is a step down switching regulator with an appropriate RC oscillator in the circuit this component outputs 18V DC with a maximum of 10 amperes It is provided in a 15 lead multiwatt plastic power package which requires an adequate cooling system We use this board to power the MacMini A little trick is needed when powering the MacMini without his own power adaptor because there is a e wire called iSense which allows the boot Without this wire the MacMini will not boot The following is the schematic of the board as provided bv ST RESET DUT DC DC 24V to 5V board We implemented the evaluation board of the ST L4973 3 5A step down switching regulator This board is significantly smaller than the
4. It is the number of no command cycles after that the program disable the engine The advice value is 5000 e maxtc0 MAX tick for motor 0 It is a positive integer value between 1 and 250 it depend on battery condition advice value is 240 This value can be computed using the auto tuning command e maxtcl MAX tick for motor 1 It is a positive integer value between 1 and 250 it depend on battery condition advice value is 240 This value can be computed using the auto tuning command e ticsp0 ticks to space for motor 0 It represents the covered space in millimeters by one tick To calculate this value we have to follow two steps First of all we have to reset encoder counters using command r2e and then move the robot by hand with motors disabled by one meter straight Then we have to use the command 12e again to read the ticks number We have to move the robot very slowly to have an exact measure We have to repeat this step many times to have a reliable ticks number The second step is calculate the ticks to space value We have to use the formula 1000 TICKS TO SPACE 0 PICKS TO_SPACE0 PERMETER where TICKS PER METER is the ticks number we have just retrieved It is a positive floating point value e ticspl ticks to space for motor 1 It represents the covered space in millimeters by one tick To calculate this value we have to follow the steps shown above It is a positive floating point value If we w
5. computer s case itself is easily extricable from the robot A set of security power switches and LEDs grants an easy emergency stop and diagnosis of the robot s status Robot packages The main units of RoboCom are The robot s skeleton The battery pack The electronic case The Mac Mini e The radio remote emergency stop Optional components are e Omni directional camera with support e Additional battery packages e Battery charger FOTO Chapter 2 Specifications Main components DISEGNO AUTOCAD CON SPIEGAZIONE Physical characteristics Measures Global Width mm 600 Depth mm 540 Height mm 790 Case Width mm 510 Depth mm 350 Height mm 270 Main plane Width mm 510 Depth mm 350 Height mm 370 from ground Battery pack Width mm 300 Depth mm 120 Height mm 90 Electronic case Width mm 320 Depth mm 100 Height mm 120 Mac Mini Width mm 165 Depth mm 165 Height mm 50 Vision system Width mm 120 Depth mm 120 Height mm 420 Materials Special profiles Item profiles www item info Product code 370 03 370 03 370 03 370 03 370 03 370 86 370 86 419 01 Other materials Length mm 510 00 514 00 156 00 199 00 284 00 268 00 284 00 260 00 Quantity Description Profile 5 20x20 natural Profile 5 20x20 natural Profile 5 20x20 natural Profile 5 20x20 natural Profile 5 20x20 natural Profile 5 80x20 natural Profile 5 80x20 natural Profile 6 30x30 natural
6. defined as private struct termios The structure Termios describes a general terminal interface for controlling asynchronous communications port In order to use this structure we must include termios h header file To see the other functions descriptions use Linux man pages Commands In this section we describe the commands available to use the IRABoard The basic syntax of a command is lt COMMAND gt lt DEVICE gt lt VALUE1 gt lt VALUE2 gt Where e lt COMMAND gt is the specific command we want to execute e lt DEVICE gt is the device we want to command Possible values are 0 for the motoro 1 for the motor 2 for both motor0 and motor e lt VALUEx gt is the command parameter if exists This value can be a motor set point or a value we want to store into PIC EEPROM The lt VALUEx gt is optional because it is not used by all commands it will be specified in the appropriate section The command is finished when we send the terminator character that is a carriage return If we are using a terminal emulation program such as minicom or HyperTerminal we must press the enter key If we are using a program test we must insert the character r at the end of the command string In this manual we indicate the variables between lt and gt and optional variables between T and J Enable Motors This command enable the motor specified in the lt DEVICE gt value its syntax
7. hardware along with their rationale Microprocessor Clock and Oscillator Frequency Since the oscillator frequency is correlated with the clock frequency according to the following formula Fclock 1 4 Fosc we have chosen the maximum oscillator frequency allowed which is 40 MHz on the PICI8F452 Notice that in order to obtain this frequency a particular oscillator configuration must be used 10 MHz crystal and HS PLL oscillator mode2 Pulse Width Modulation Pulse Width Modulation PWM is a common and simple way for interfacing digital and analog devices Since in IRABoard the control logic is programmed with a digital microcontroller and the DC motor is driven by an analog power circuit we use PWM to connect them A PWM signal is a periodic signal made up of pulses Per with a variable width Period and duty cycle that is the ne ER c width of the pulses in time units are the characteristic parameters of such a signal see figure beside Duty Cycle Period is fixed during the operation of the system and the main considerations that must be addressed regarding its choice are e Audible frequency band the PWM frequency must be outside the audible frequency band otherwise a disturbing noise would be heard e Compatibility with analog circuits the PWM frequency must be chosen so that analog circuits that will receive that signal as input would be able to process it The PWM period can be specified
8. load speed at gear output min 1 103 Max cont torque at gear output Nm 9 1 Interm perm torque at gear output Nm 23 Length mm 161 9 Planetary Gearhead Gear order no 203123 Description Planetary Gearhead GP 42 C 042 mm 15 Nm ball bearing ceramic Reduction 74 1 Number of stages 3 Max cont torque Nm 15 int permissible Torque Nm 23 Max efficiency 72 Average backlash unloaded deg 1 0 Mass inertia gcm2 15 Gearhead length mm 69 9 Weight g 460 Max motor shaft diameter mm 10 0 Motor Motor order no 148867 Description RE 40 40 mm Graphite brushes 150 Watt Power rating W 150 Nominal voltage Volt 24 0 No load speed Stall torque Speed torque gradient No load current Starting current Terminal resistance Max permissible speed Max continuous current Max continuous torque Max power output at nominal voltage Max efficiency Torque constant Speed constant Mechanical time constant Rotor inertia Terminal inductance Thermal resistance housing ambient Thermal resistance rotor housing Thermal time constant winding Length Weight Tacho Tacho resolver order no 110513 Description Axle diameter mm Counts per turn Number of channels Max operating freq kHz Diameter mm Length mm Transmission 4 500 3 100 10 21 0 min 1 Nm min 1 mNm 1 mA A Ohm min 1 mA mNm W mNm A 1 min 1 V 1 ms gcm2 mH KW 1 KW 1 S mm g 7580 2 28 3 33 137 76 0 317 12000 5
9. written in an incremental form so that the control law is u k u k 1 K e k e k 1 Kj e k Ka u k y k 1 y k 1 4 y k 2 where u k is the control output at instant k e k is the error at instant k y k is the process output at instant k Notice that this formulation differs from the standard continuous time PID controller here the derivative action is applied on the process output not on the set point This approach guarantees smoother control action behavior in case of a set point step variation From the software point of view the control algorithm is contained into a subroutine that is called with a fixed sampling time period and its main tasks are e Reading encoders data stored into timers e Computing control output e Applying the control output Regarding the first sub task it is needed in order to compute current motor rotation speed which compared to the set point value yields the control error Although this would seem a natural and simple way to design the control routine it is not efficient two ratios between two big integers should be computed at each control cycle and this is a time consuming operation for a microcontroller with limited resources We adopted the following strategy instead of comparing the computed speed with the set point the set point is transformed in a way that can be directly compared with ticks This transformations require two ratios too but they are computed eve
10. 770 170 438 91 30 2 317 138 0 082 4 7 1 9 41 6 71 0 480 Digital Encoder HEDS 5540 10 mm 500 counts per turn 3 channels The transmission for each motor wheel consists of two pulleys and a belt We chose the belt based transmission with the aim of minimize the maintenance operations Indeed the belts don t need any maintenance at all while the chains need lubrication and cleaning The two motors are not placed at the same height in order to reduce robot s width With this trick we gain in width 6 cm The upper pulley is fixed on the motor s shaft the torque transmission granted by a XXXXXXXX linguetta The toothed belt transmits the motion to the lower pulley which is fixed on the wheel s shaft This shaft is steel made so as to resist to any possible solicitation and is hold by two ball bearings The following scheme shows the transmission system BALL BEARINGS WHEEL S SHAFT LOWER PULLEY Wheels The robot has two drive pneumatic spoked wheels in front moved by the motors and a pivoting wheel on the rear The front wheels are fixed on the steel shaft which receives motion by the belt Technical data Front Producer Product number Wheel diameter Hub diameter Wheel thickness Wheel weight Rear Producer Product number Wheel diameter Pivoting plane height FOTO 3Emme Italy www 3emme com 260DALPN17 black tire mm 260 mm 17 mm 80 Kg 1 48 GS Euromarket ht
11. RoboCom User manual and documentation IRALab University of Milano Bicocca D I S CO Table of contents Table Of contents P 2 Chapter 4 Robot packages l 4 Gh pter 2 Specificatiors a i aee reae er EE E n ge evens eas 5 Maiti componehts ese a a Le ete tti ett t inches he ttd ive eS 5 Physical characteristics eden e ER Ue EET d CEU D evn Rieti adh ei ure ERREUR 5 hunc EE 5 Me tih RO E tat ae leeds Meas E pee a aa B a a 6 Special profiles xa ne eo RON be Waren er ue ipd eh Une ue ete rd 6 Other materials eh ee Eo ere A 6 tette ROME NS e IT 6 Batteries sane had ait A eue Dei gd LL ARABES LN LT Ate RT d deese LS ere 7 Charging ig e Reve E OC DU Ge ERREUR cv tlg e Ro Gee a Go ences RR a 7 El ctrica Re m e tente o dte eerta t RD De terit ec dubitem eee ans 8 E 9 DE DE 24V to TEV board e hag vacet See trad va ee rede ene DR aeneae A eaten 9 DC DC24W 0 5 V board sa ei p Eee Re PE II ete Rap tete te dux Eee t S Eo Eee 10 C 10 ovde m EE 10 Spe iticatiotis MERI ODER ILL UELLE 11 huj cpu 13 Maxon Codes REDEEM E ara etes e iR poe o FAR EAE 13 Combination technic
12. abeled with his number furthermore verify that the value is positive when you rotate the wheel clockwise and negative when you rotate the wheel counterclockwise Do the same for the Motor 1 If something goes wrong verify you plugged the connectors the right way Let s now verify the motors LIFT THE ROBOT SO THE WHEELS DON T THOUCH THE GROUND AND ARE FREE FOR ROTATING Type the command T2 WARNING be very careful while using this command because it sets both the motors rotation speed at maximum clockwise for several seconds When the wheels stop look at the minicom window you should read the following TICK MOTOR 0 1349 TICK MOTOR 1 1352 the values may change in a little range If one of the two values is 0 there is a mistake with the motor wires Verify that you plugged the right motor in the right female connector on the IRABoard If all behaves like you expect the robot is well settled Start testing your command software Now all is ready for start using the robot See the next chapter for the documentation of the IRABoard firmware and communication then write your code and enjoy the RoboCom Chapter 4 IRABoard documentation The whole content of this chapter is taken from the AIRBoard user manual with only some modifications to match the hardware differences Design Choices In this section we will explain in detail the design choices in the design of the IRABoard control unit software and
13. al data sse nee nenn mnn 13 Planetary Gearhead EE eet ie 13 IP 13 B Tela A 14 besi DE 14 hj pc HUI E 16 Mac Miti zn rene DHT n ERO o Oe e e He RM ER HE OTRO DRE FER OD DRE REI magna ss 17 oir oe e eee e ee D e E er e ir 17 Nub PE ati 17 Vision system optional nee tiec beste tie elei teet te tede cute Ine IIa ere 18 C atmetd cesi aes reine RO PR EI UR OO UE EE CE EE EORR E TOT TE HE E TU ER te a 18 MIEL nuin RR UE UH ERE ER Re pro e Ue e eter a ER HE EE EHE 18 Tuning plane AIR nep RINT eie HER ORI eie E 18 Chapter 3 Start using RODOCOM 5 ii ara ee d eR e epe re peus 19 nonna TSA eY LES BiA e 1e AEE A A 19 Inserting battery pack electronic case and 19 Connect all the plugs and switch on the robot nennen enne enne enne 20 The electronic case connectots sies etate tie Ue e e ERE RTI ER ER Ee T ede edes 20 The MacMini connectors sce e ede eere ede P e ER a see eden 20 The power connector eee emite RH RE Re e ELE 20 Verify serial connection encoders and motors sese eere enne nre enne enne 20 Start testing your command 2 21 Chapter 4 IRABoard documen
14. alid characters or sequences which commonly causes the PIC s firmware crash For the v1 1 we redesigned a big part of the circuit optimizing the space and shorting the communication wires The result is a robust board which we tested for more than 5 hours of continuative work Specifications The main components of the logic part of the board are The PIC18F452 Microchip s microcontroller This component is the operating core of the entire board It communicates via RS 232 with the MacMini interfaces with the HCTL in order to retrieve the encoder count and generates the PWM signal for both the H bridges For more information about the firmware see the dedicated section Follows a list of the main features of this microcontroller e Linear program memory addressing to 32 Kbytes Linear data memory addressing to 1 5 Kbytes Up to 10 MIPs operation DC 40 MHz osc clock input 4 MHz 10 MHz osc clock input with PLL active 16 bit wide instructions 8 bit wide data path Priority levels for interrupts 8 x 8 Single Cycle Hardware Multiplier Two Capture Compare PWM CCP modules PWM output PWM resolution is 1 to 10 bit Addressable USART module Supports RS 485 and RS 232 Single supply 5V In Circuit Serial Programming ICSP via two pins In Circuit Debug ICD via two pins The HCTL 2032 Agilent s Quadrature Decoder Counter Interface This component receives the signals from the two encoders decode them and count the ticks of the moto
15. ant to write a variable into the EEPROM we must also specify the value to store adding lt VALUE gt in the command syntax The value representation is the same of normal computers if the value is a floating point we must use a dot to separate integer and decimal part while if the value is an integer we must write an integer number Now we will show some example of use erkd0 1 ERROR 7 error bad command ewkil ERROR 7 error bad command erki2 ERROR 7 error bad command er ERROR 7 error bad command The command sequence above shows some example of typical error The first command is wrong because we want to perform a read but we also specify a value The second command is wrong because we want to perform a write but we do not specify any value The third command is wrong because we specify a not existent mnemonic string The fourth command is wrong because we do not specify any parameter ewkd0 1 5 write in the internal Eeprom the value for OK operation ok erkd0 read from the internal Eeprom the value for kd0 kd0 1 5 X the value for kdO is printed OK operation ok This command sequence shows two correct commands The first command write the value 1 5 in the EEPROM space associated to the mnemonic string kd0 The second command retrieve from EEPROM memory the value of variable kd0 and write it on the serial bus Return distance or speed This command allows to read the current spee
16. are programming with C An example of initialization code constructor method could be the follow SerialCommunicationAIR Board SerialCommunicationAIR Board mBaudRate B115200 mModemDevice strdup dev ttySO mHardwareFlowControl false InitCommunication StartMotors hi The functions InitCommunication and StartMotors start respectively the serial communication and the motors The InitCommunication function initializes the serial port with the correct configuration bits An example of initialization communication could be the follow void SerialCommunication InitCommunication void Open modem device for reading and writing and not as controlling tty because we don t want to get killed if linenoise sends CTRL C if fd open mModemDevice RDWR NOCTTY lt 0 perror mModemDevice exit 1 save current serial port settings tcgetattr fd amp oldtio clear struct for new port settings bzero amp newtio sizeof newtio BAUDRATE Set bps rate You could also use cfsetispeed and cfsetospeed CRTSCTS output hardware flow control only used if the cable has all necessary lines See sect 7 of Serial HOWTO CS8 8n1 8bit no parity stopbit CLOCAL local connection no modem contol CREAD enable receiving characters if mHardwareFlowControl j else newtio c_cflag mBaudRate CRTSCTS CSS CLOCAL CREAD newtio c_cflag mB
17. audRate CS8 CLOCAL CREAD IGNPAR ignore bytes with parity errors ICRNL map CR to NL otherwise a CR input on the other computer will not terminate input otherwise make device raw no other input processing newtio c iflag IGNPAR ICRNL Raw output newtio c oflag 0 ICANON enable canonical input disable all echo functionality and don t send signals to calling program newtio c_Iflag ICANON initialize all control characters default values can be found in usr include termios h and are given in the comments but we don t need them here newtio c_cc VINTR 0 Ctrl c newtio c cc VQUIT 0 Ctrl newtio c cc VERASE 0 del newtio c_cc VKILL 0 newtio c cc VEOF 4 Ctrl d newtio c_cc VTIME 0 inter character timer unused newtio c_cc VMIN 0 blocking read until 1 character arrives newtio c cc VSWTC 0 0 newtio c_cc VSTART 0 Ctrl q newtio c cc VSTOP 0 Ctrl s newtio c_cc VSUSP 0 Ctrl z newtio c_cc VEOL 0 0 newtio c cc VREPRINT 0 Ctrl r newtio c_cc VDISCARD 0 Ctrl u newtio c_cc VWERASE 0 Ctrl w newtio c_cc VLNEXT 0 Ctrl v newtio c cc VEOL2 0 0 now clean the modem line and activate the settings for the port tcflush fd TCIFLUSH tcsetattr fd TCSANOW amp newtio terminal settings done now handle input Variables newtio and oldtio are
18. because the libraries of each compiler has been written for one specific PIC family The code The program has been divided in various modules each of them performing a particular function Every module has been organized with the ANSI C typical structure an header file h extension that contains the functions and local variable declarations and a code file c extension that contains the functions source code There is also an header file that contains all global variable declarations and all definition strings the classic DEFINE preprocessor directives definitions h This header file is the most important because it contains all constant strings and global variable definitions The constant strings define preprocessor directive are very important because we can indicate each PIC pin with a mnemonic string In this way if we change pin layout we have to change only the define string without changing the mnemonic string in the code The define directive is also useful for other characteristics we can define mnemonic strings with a particular value or define boolean variables and all Eeprom mnemonic strings Global variables are useful because they keep their value even when the subroutine has finished and these values are available to each module We have chosen to use many global variables to keep the variable value for different elaboration steps and in each module We can find in definitions h all global communication buff
19. ce choice and others parameters needed for correct working of PIC with suggested values see below in Using internal EEPROM section Possible examples c2 configure both motors c0 configure only motor 0 Using internal EEPROM This command allow to use PIC internal EEPROM to save robot and control parameters The syntax is slightly different from other commands since we have to specify the operation we want to perform and not the device The syntax is e lt OPERATION gt lt VARIABLE gt lt VALUE gt There are only two possible values for lt OPERATION gt r read a value from EEPROM Ww write a value to EEPROM We have to specify also the variable we want to save or restore Each variable is contained in lt VARIABLE gt and it is represented by a mnemonic string Strings representing variables are kd0 motor 0 control derivative constant It is a positive floating point value ki0 motor 0 control integrative constant It is a positive floating point value kp0 motor 0 control proportional constant It is a positive floating point value kd1 motor 1 control derivative constant It is a positive floating point value kil motor 1 control integrative constant It is a positive floating point value kpl motor 1 control proportional constant It is a positive floating point value ct controller sampling period multiplier It is a positive integer value It is expressed in milliseconds The advice value is 10 e
20. character arrives this subroutine retrieve it from rs232 input register and copy it in the command buffer When a terminal character carriage return is received the command buffer is passed to the proper subroutine for command parsing and execution controller c This file contains the controller subroutine It contains only one subroutine but it is the most important in IRABoard since it is the engine controller algorithm Actually the engine control is a digital P I D but it is possible to write in IRABoard any type of control e g fuzzy controller If we want to change control algorithm we have to modify this file The only subroutine contained in this module is e engine control this is the subroutine that contains the engine control algorithm eeprom c This file contains all EEPROM subroutines This module is not the original Microchip because it does not exist We have written this module with datasheet information The address necessary for store or load data is 8 bits data the only reason for this choice is that EEPROM maximum size is 256 bytes and with 8 bits we can cover all memory space The subroutines contained in this module are e readByteFromlIE it reads a single byte data 8 bits from the EEPROM memory Example of use is data readByteFromIE address where address is the memory location of the data we want e writeByteTolE it writes a single byte data 8 bits it the EEPROM memory Example of use is writeBvteT
21. connect at least the power connector coming from the electronic case and the USB plug of the USB USART converter also coming from the electronic case Other devices may be plugged like the omnidirectional camera sonar or laser devices and similar The main power connector LAST remember LAST you need to connect the main power connector to the battery pack s one you settled up before Be very careful to plug this connector the correct way otherwise you may irremediably damage the robot At this point you may switch the power switches on and begin the test phase Verify serial connection encoders and motors If you completed all the previous steps then now you can switch on the MacMini When logged run minicom in a command window and try to send some commands to the robot On each command you send two events must happen e The communication led on the board the yellow one will change his status blink e Aresponse to your command should appear on minicom Try to execute the command C2 on minicom it should appear the string OK Let s test the encoders Type the command D3 minicom will start to write the motion controller status Two values are important for us EO and E1 the encoder reads Rotate the robot s wheels clockwise and counterclockwise the EO and E1 values should change Verify that the EO value changes when you rotate the wheel corresponding to the Motor 0 each motor is l
22. d by comparing each other The third signal provides zero crossing and could be used as a reference point for precise angle determination In our setup Channel A and B are processed by the HCTL2032 which we already discussed Serial Line Interface The IRABoard can be interfaced to any device through a common RS232 serial line connection This interfacing method has been chosen for several reasons e The PIC18F452 has a built in USART circuit that allows easy serial communication from the software point of view e RS232 interface is commonly available in almost every personal computer e Only few electronic components are needed to build the circuit responsible for TTL RS232 signal level conversion Among the drawbacks of serial lines the most important one is the limited data transfer rate that they can achieve This is not an issue in our case due to the limited computational resources available that prevent us from setting too high baud rates Regarding serial line settings in our setup we have chosen to operate in a full duplex asynchronous fashion data can flow in each direction as soon as it is produced without clock synchronization issues Each character sent over the line is represented by 8 bits with one start bit and one stop bit Baud rate used is 115200 bps In IRABoard serial line data management is interrupt driven when a character is received into the RCREG register an interrupt will be raised and the corresponding interrupt se
23. d space only for motor 0 453 the covered space for motor 0 OK operation 05 print speed only for motor 0 23 the current speed for motor 0 OK operation ok In this example the commands print the covered space and the current speed only for motor 0 Debug information This command allows to change debug level and the information returned by IRABoard This feature is useful to get values and messages during IRABoard tests Its syntax is d lt DEBUG VALUE gt lt DEBUG VALUE gt is the value of the debug level The values are e 0 it does not return any message It is the default value e it returns only the command results OK if the command execution has successfully terminated ERROR code if the command execution has failed e 2 it returns advanced debug messages such as intermediate elaboration results It shows EEPROM operation result and enable disable operation on kicker and motors e 3 it returns ALL messages even the controller results set point PWM and tick step by step Warning This causes slowing down in the execution because of writing on the serial bus We recommend to use this feature with a monitor and terminal emulation program such as HyperTerminal under Windows or minicom under Linux We have said above that when a command execution fails an error message is printed with a special code They are e ERROR I bad device This error is shown when we indicate in the command a device not valid
24. d value and the covered distance since last read command its syntax is r lt DEVICE gt lt TYPE gt lt DEVICE gt is the device we want to query for distance or speed lt TYPE gt is the data type we want to check The possible values are we want to read the speed It is expressed in ticks second e we want to read the space It is expressed in ticks lt TYPE gt is optional since we may want both current speed and covered space for both devices In this case we must write only the command r2 without any other parameters and the AIRboard will return speed and space for both devices If we do not want both TYPE is required Now we will show some example of this command r2 print both distance and speed for both the motors 453 345 the covered space for motor0 and motorl 23 67 the current speed for motor0 and motorl OK operation ok This example shows the use of command r2 it returns both speed and covered distance for both the motors Here we have not specified the TYPE so IRABoard has returned all data r2e print covered space for both the motors 453345 the covered space for motor0 and motorl OK operation ok r2s print current speed for both the motors 23 67 the current speed for motorO and motor1 OK operation ok This command sequence has the same effect of the previous but here we have used two commands instead of one As we can see the results are the same r0e print covere
25. er encoders and controller variables ROBOT MAIN c This is the main file It contains all global variables declarations the interrupt service routines and the command interpreter When we turn on the IRABoard the sequence of operation is 1 Initialize all pic feature 15232 timer and PWM Load from internal EEPROM all controller constants 3 Start an infinite loop this is a polling loop which can be interrupted by serial bus and control interrupt service routines When IRABoard receives a terminal character carriage return from communication buffer it calls the interpreter routine to parse the command and then execute it if valid We can see this sequence in the diagram on the next page The subroutines contained in this module are e control isr this is the control interrupt service routine It is called each sampling period e rs232_isr this is the serial bus interrupt service routine It is called at each character arrival from the serial bus e executeCommand this is the subroutine that execute the command received from the upper layer It is called when the serial bus isr receive the end string character carriage return e Setup this is the initial PIC setup routine It sets all pic features we need e restoreData this is the subroutine that load all pic parameters from pic internal EEPROM It is called after Setup subroutines e main the main subroutine PIC Setup Restore PIC data Read fro
26. he range 0 500 As stated above the PWM duty cycle express the desired motor rotation speed computed by the control logic Since for a generic DC motor we can have two direction of rotation we have two information direction and rotation speed that need to be communicated to the analog circuit This is performed by a signal that carries only this information the direction bit In addition our H bridges accept the brake information implemented inverted low brake which signals to the bridge to stop the motors The H bridges when the brake bit is low short circuit the two motor wires together this action forces the current induced by the inertial motor rotation to re enter in the motor strongly braking the rotation Encoders The encoder measures the motor rotation speed providing a feedback to the control logic We used optoelectronic encoders produced by HP As can be read from Maxon catalogue they work according to the following principle a LED light is sent through a finely screened code wheel that is rigidly mounted onto the motor shaft The receiver photo transistor changes light dark signals into corresponding electrical impulses that are amplified and processed in the electronics These encoders provide three signals two of them Channel A and B are 90 phase shifted square signals that can be counted for exact motor shaft positioning or rotation speed determination furthermore rotation direction can be derive
27. is a lt DEVICE gt lt DEVICE gt is the device we want to enable When a motor is enabled it will start the control action to react with the current set point it could have been previously set Before enabling a motor it is better to set the correct set point the default set point values are zero so that the robot will not move even if we enable motors without giving set point values Possible examples a2 start both motors a0 X start only motor 0 Disable Motors This command disable the motor specified in the lt DEVICE gt value its syntax is b lt DEVICE gt lt DEVICE gt is the motor we want to disable When a motor has been disabled every change in set point value will not produce any result until next habilitation The motors will be automatically disabled after a number of cycles with no command set in the Eeprom Possible examples b2 disable both motors bl disable only motor 1 Change Set point Value This command allow to change set point values for the motors its syntax is m lt DEVICE gt lt VALUE0 gt lt VALUE I1 gt lt DEVICE gt is the motor for which we want to change set point According to the devices we can have different values When lt DEVICE gt is equal to 0 or 1 the new set point value is lt VALUE0 gt and lt VALUE I gt is not used when DEVICE is equal to 2 we must use both lt VALUE0 gt and lt VALUEI1 gt Some examples are for simplicity we will consider the mot
28. k is assembled put them in the robot the way indicated by the arrows on the battery container now push them in the direction of the motors until the pack reaches the motor plane border The battery pack is in position The electronic case must be placed beside the battery pack Put the case in the remaining space beside the battery pack and push them to the end Finally remains the MacMini Put them in the appropriate space on the rear of RoboCom the I O ports on the right side of the robot Fix them with the belts Connect all the plugs and switch on the robot There are some plugs you may need to connect disconnect while working with RoboCom The electronic case connectors There is the main connector a big plug you ll see in the area of the case It includes the power wires coming from the batteries switches and going to the MacMini and the remote emergency stop The motors wires come from the motors and terminate in two green easy on plugs Plug this male connectors to the correspondent female on the IRABoard as indicated by the labels The encoder wires come from the encoders and terminate in two black little plugs Plug this male connectors to the correspondent female on the IRABoard as indicated by the labels The RS232 serial connector coming from the MacMini is the last connector you must plug On the IRABoard it must be plugged on the bottom of the front side of the board The MacMini connectors On the MacMini you need to
29. m RS232 bus Program Execution Interrupt from RS232 Waiting for commands Control action Parse and execute command Interrupt from Controller rs232 c This file contains all rs232 serial bus subroutines This module is not the original Microchip s because the original had some bugs specially in the putsUSART and putrsUSART subroutines so we rewrote it The new version is so smaller than the original and contains only the subroutines necessary for our application The subroutines contained in this module are e putsUSART this is the subroutine that writes a string on the serial bus The string has to be placed in the PIC RAM memory this means that the string must not be within the double quote i e constant string Example of use is putsUSART variable where variable is a string variable e putrsUSART this is the subroutine that writes a string on the serial bus This string has to be placed in the PIC ROM memory this means that the string is a constant string write within the double quote Example of use is putrsUSART Welcome in IRABoard e ReadUSART this is the subroutine that read a single character from the serial bus Example of use is character ReadUsart e WriteUSART this is the subroutine that write a single character into the serial bus Example of use is WriteUSART v e read 15232 this is the subroutine called by serial bus interrupt service routine When a
30. ogrammable postscaler This means that an ISR will be called every fixed amount of time that must be a multiple of the PWM period In our case the chosen sampling time was Ts 100Hz To have the control routine called 100 times per second we set TMR2 postscaler equal to 10 and a software trick has been introduced so that the control routine is called every 20 TMR2 interrupts Concurrency issues In order to make the whole system correct with respect to concurrent behavior the ISR with the control routine runs at low priority This means that the control routine can be interrupted only by the RS232 ISR which has high priority This may cause delays but they are of little amount since RS232 ISR has short time execution This gives us two advantages e No serial received character will be overwritten since RS232 ISR will be executed as soon as the character arrives on the receiving buffer e The RS232 ISR is executed as an atomic operation which is needed to preserve correct program state since multiple memory location are accessed modified by it Furthermore since the control routine is executed into an ISR it can interrupt program body execution command string parsing for example guaranteeing to be executed at a given frequency Eeprom As you can see in Datasheet errata about pic18Fxx2 family when reading the stored data the contents of the EEDATA register may be corrupted if the RD bit EECON1 lt 0 gt is set immediately foll
31. olE address data where address is the memory location we want store the value and data is the value to save e loadEEPromValue it reads a floating point value from the EEPROM memory The floating value is stored in scientific notation mantissa and exponent so we can store a big range of number with few memory locations Example of use is value loadEEPromValue address where address is the memory location of the value we want e storeEEPromValue it writes a floating point value in the EEPROM memory Example of use is storeEEPromValue address value where address is the memory location we want store the value and value is the value we want to save Chapter 5 How to use IRABoard The use of IRA Board is very simple First of all we have to configure the serial bus with the proper values otherwise the communication will not be possible For testing the communication we can use a terminal emulation program HyperTerminal on Windows or Minicom on Linux or a test program written in C C language The values to use are bus speed 115 200 bps hardware flow control disabled bit parity no parity eventual modem initializations disabled Test program in C C Language We can use IRABoard with a test program written in C or C language To use a test program we have to include the header file sstream h and then we must create a function to initialize the serial communication We can do that in the constructor method if we
32. ors always active m1 010 010 set motor ERROR 7 error bad command ml 010 set motorl OK operation ok m2 020 set both motors ERROR 7 error bad command The command sequence above shows a typical use of this command As we can see the first command produces an error because we have chosen to change set point value only to motor but we have specified two values The second command is correct since we have specified only one value to 1 The third command produces an error since we have chosen to change both set point values but we have passed only one value m2 000 000 set both motors OK operation ok m0 050 set only motorO OK operation ok m1 050 set only motor OK operation ok m2 099 099 set both motors OK operation ok This command sequence shows the use of all cases without errors The first command stops both the motors they are still enabled The second command change set point value only to motor0 The third command change set point value only to motorl now both engines have the same set point value The fourth command change set point value to both the motors When the motor is controlled in speed the new set point value is expressed in MAX speed percentage and it can be both positive and negative The MAX speed value is in absolute value 100 and the MIN value is 0 value greater than 100 or less than 100 takes the controller to saturation zone If we want to move the
33. owing a write to the address byte EEADR A NOP instruction between the registers writing should solve the problem Source Code Description The language The code has been written in C language It is not an ANSI C but it is a Microchipl version very similar to the ANSI C including some libraries such as string h rewritten for working on small devices with a little amount of memory and low computer power The most important thing while programming this device is clock cycles saving it is better to have longer code than compact code but slower to execute However we must remember that PIC has a little amount of memory and the code cannot be too long This is the trade off we have considered programming the PIC The environment The entire code has been written with MPLAB IDE environment v6 30 by Microchip The code can be modified with any text editor but we advise to use this suite because the PIC18 specific compiler can be easily integrated with this environment MPLAB IDE allows also to compile the source code to obtain the hexadecimal file that must be written on the PIC MPLAB IDE can write the hexadecimal file on the PIC but also different program can do it The compiler The code has been compiled with MPLAB C18 compiler v 2 20 by Microchip This compiler has been designed to be integrated with MPLAB IDE suite This is the specific compiler for PIC18 family If we change PIC family i e PIC17 family we must change the compiler
34. previous one the component is provided in a 18 pin PowerDIP package and needs only a few components The ST L4973 component is a step down switching regulator with an appropriate RC oscillator in the circuit this component outputs 5V DC with a maximum of 3 5 amperes We use this board to power the IRABoard v1 1 for the logic sub circuit See also the Future work section The following is the schematic of the board as provided by ST Voc l DIP18 R2 7i L4973 2 c7 m L1 Vo Q 10 1244 45 R4 L1 JI ws D97INS15C gt IRABoard v1 1 Evolution The IRABoard v1 1 is the empowered version of the IRABoard v1 0 while the IRABoard v2 0 is currently under development This family of powerful boards have grown from the experiences achieved by the IRALab in the last years This experiences drove us to very important improvements which will be discussed in the following During the development of the v1 0 we encountered heavy problems due to the electrical noise driven by the H bridges In order to solve that critical situation the noise disturbs reset the microcontroller we decided to physically divide the two sub circuits i e the logic and the power one over the same board The resulting v1 0 worked well under some conditions but it revealed to be unreliable in normal robot activity conditions The biggest problems was the RS 232 communication between the board and the PC inv
35. r s rotation The counter are two 32bit signed registers one for each motor which are accessible to the PIC via an 8 bit tristate interface The microcontroller periodically reads this value and resets the counter Follows a list of the main features of this microcontroller e Up to 33MHz clock operation Programmable count modes 1x 2x 4x High noise immunity Schmitt trigger inputs and digital noise filter 32 bit binary up down counter 8 bit tristate interface 8 16 24 or 32 bit operating mode TTL CMOS compatible I O 32 pin PDIP The MAX232 component for the voltage conversion of the RS 232 signal The LMD18200 H bridges by National Semiconductors The LMD18200 is a 3A H Bridge designed for motion control applications The device is built using a multi technology process which combines bipolar and CMOS control circuitry with DMOS power devices on the same monolithic structure Ideal for driving DC and stepper motors the LMD18200 accommodates peak output currents up to 6A This components are the power supplier for the motors according to the PWM direction and break signals coming from the microcontroller An ICD2 interface is also built on the board to allow easy microcontroller reprogramming This is the schematic of the IRABoard v1 1 Motors The motors are a Maxon product The specifications are the following Maxon codes Gear 203123 Motor 148867 Encoder 110513 Combination technical data No
36. robot to its MAX speed we must set the set point value to 100 or 100 if we want to change the direction If we want to stop the robot without disabling motors we have to set the set points value to 0 The sign represents the direction of motor rotation Usually with positive set point values the motor rotation is clockwise and with negative set point values the motor rotation is counter clockwise Warning If the wheels are opposed such as with bidirectional robots and we want to move the robot on a straight direction we must set one set point positive and the other negative This is necessary because if we set both set points with the same sign the wheels will rotate both clockwise and robot will turn around itself We have chosen to represent the speed as max value percentage when the motor is controlled in speed and not with absolute values such as in cm sec because we are always sure that 100 represent the MAX speed even if we change motors or wheels while absolute speed value may change Configuring parameters This command configure the control parameters of motor specified in the lt DEVICE gt value and other parameters its syntax is c lt DEVICE gt lt DEVICE gt is the device we want to configure This command is useful if we want a quick configuration of all parameters The parameters configured are the constant of the PID controller kp 0 5 ki 0 1 kd 0 3 and maxtick value maxtick 240 according with devi
37. rvice routine ISR will be executed Notice that this is an high priority ISR meaning that it cannot be interrupted by any other ISR Received characters are copied into a buffer to store the whole command string When the terminator character v is received the buffer content is transferred into a second buffer where the complete command string can be parsed Control PID Control The process that IRABoard will control is a DC brush motor From control point of view this system can be modeled as a second order system where input variable is the voltage applied to the motor armature and output variable is the rotation speed From the physical model of the motor we can derive the following transfer function applying Laplace Transform K where e Kisthe electromotive force constant e Jis the moment of intertia of the motor e Lis the electric inductance e 15 the electric resistance b is the damping ratio We have chosen a closed loop control system control action output setpoint error Controller This control architecture ensure both high disturbance rejection in noisy environments and low residual error with respect to open loop control systems This can be done thanks to the feedback provided by the encoders The control algorithm implemented is a digital PID This kind of controller is common in industry and suits well in control systems where process can be modeled as a second order transfer function It is
38. ry time the set point is changed not at each control cycle The second sub task computation of control action is done according to the above depicted control law In order to do this we need to maintain state variables to store past errors control action and process output It is worth to notice that attention must be paid in order to avoid the integral windup problem that affects PID controllers This problem may cause very large response times of the controlled system due to the presence of an integrator which in case of control output saturation may diverge A solution for this problem is the following the discrete integrator part of the PID algorithm is stopped when the control output saturate preventing the integrator from reaching too large values In other words the sum that realize the discrete integrator is not performed when control action saturate Third sub task involves the control action application A saturation must be introduced here since PWM duty cycle values must stay in a given set Timing issues In IRABoard in order to perform control action every sampling time a timer generated interrupt is used Our PIC is equipped with three hardware timers registers of which only the third Timer2 is used It performs the counter within the PWM circuit as a time base generator and must be set to operate at the PWM frequency Fortunately it is also possible to use this timer as an interrupt generator with a pr
39. tation cesccccssccssescesessssseessesecncesscseescsseeseesecseesecuseseesaeesessecaeesecseeseesaeeseaecaeeseeneeseenaes 22 Desigt Choices E UN itu iim tulisti 22 Microprocessor Clock and Oscillator Frequency sees 22 Pulse Width Modulation MR 22 MI asi ask SA Hd 23 Serial Line Interface duet Re SIRO RP Re UB RATIS 24 Control Ue ERA AP Ia festus late cas ied cet aa odia oad 24 PID Control nee A ee eta qn de ERR e EHE etie t ein ees 24 Timing ISSUES EROR 26 Conc tr ncy 188068 et RE te e eG GR ERU dere ede Ee E ERRARE Reve Re Pe 26 Source Code Description eee eee ea ede RC RARO E RE 27 Thedanguage 4s emo Mor e I M vL d ie 27 The enviro ment c ao uon utere tet esed e terret ore etie eto ey Pe e Dre ors REOR REN 27 hie COImpllerz t voe mu cd ine M a EE te 27 i issir M M 27 definitions i ii kies e eq eddie been elu ge gie e ER 28 ROBOT MAINS eoa a d gei tage lue pe ag 28 1923216 recede fede tede e be EE e ee e baee dte ed e de iade 29 Ue Ge s A e 30 Ug uM M 30 Chapter 5 How to use IRABoard eei e eer retener ER IE qt ge re Ue beet bep red edu 31 Test program in C C Language enne ennemi enne nennen 31 Commands oes ee o estet
40. toa ate hd et e At em eL 33 Enable e i e im bo e e o t ete ER EAT d ER CES 33 Disable dt bo tt S e dit iot ue EE d 34 Changeset point Value easet vedette item ice dede esee 34 Configuring parameters tci ee edente diii Te esi ee re Het e e e Tele eee bed eee 35 Using internal EEPROM sisa ree epe et PR RE ede eh 36 Return distance or speed ee e eene He ee ee eed e ees 37 Debug information i e e EHE RH et e EIE He e ei e eee dts 38 Auto tuning paramleters ei 39 Chapter 1 Introduction The RoboCom is a multi purpose robot designed for carrying modest weights max 50 kg in indoor and outdoor spaces The presence on the robot of a powerful PC allows both easy communications with other computers e g wireless Bluetooth etc and easy interface to sensor devices The high wheels allows the robot to drive without problems also on grass and rough grounds The motors are kept high with respect to the wheels in order to protect them against accidental hits with objects The skeleton is completely in aluminum to reduce the robot s weight and designed for high resistance to solicitations The batteries are easily chargeable no need to extract them from the robot or to charge separately thanks to the unique plug of the battery pack The electronic case is designed for quick plug in and plug out without any risk of mistakes with plugs The MacMini s I O ports are fully accessible and the
41. tp shop gseuromarket com SCP200F mm 200 mm 239 MacMini Hardware 1 83GHz Intel Core Duo processor Apple Remote with Front Row 2GB RAM Intel GMA 950 graphics processor DVI connector VGA adapter Slot loading optical drive 80GB hard drive Built in gigabit Ethernet Analog and digital audio Expansion via USB and FireWire Software By default a Ubuntu Linux distribution is installed but end user may choose alternative operating systems For robot control we provide the complete documentation of the command set which can be used via COM ports communication Vision system optional The MRT 06 is a omnidirectional vision system composed by a firewire camera a bi conical omnidirectional mirror and a tuning plane for camera centering Camera The camera is fixed on the tuning plane on the floor of the video system and is directed upwards Interface EEE 1394a FireWire 400 Mbps 2 ports 6 pins Camera Type IDC 1394 Digital Camera V1 04 Specification compliant Sensor Type Sony Wfine 14 color CDD with progressive scan I CX 098BQ Resolution VGA 640 x 480 Optics Bright F 2 0 lens with with 4 3 mm focal length Lens filters coating Antireflective coating and infrared cut filter Video Modes YUV 4 1 1 4 2 2 4 4 4 RGB 24bit Monochrome 8bit Frame Rates 30 15 7 5 and 3 75 frames per second Gain Automatic or Manual Control 0 30 dB Shutter Automatic or Manual Control 1 3400s 1 31s Gamma ON OFF visual
42. use image processing use White Balance Automatic or Manual Control Color Saturation Adjustable Backlight 6 modes OFF Compensation Sharpness Adjustable Special Features Software sleep mode Color bar generator Power Supply 8 to 30 VDC by 1394 bus or external jack input Consumption 1W max 0 9 W typical 0 4 W sleep mode Dimensions WxHxD 62 x 62 x 35 mm Housing amp Weight Silver gray plastic polymer 60 gr Mirror The mirror is a bi conical omnidirectional mirror and is fixed in front of the camera i e on the top of the vision system The image retrieved by the camera of this mirror is the conical projection of the surrounding world This image should be straighten via software Tuning plane The camera lies on a tunable plane with 2 degrees of freedom The tuning should be performed with a screwdriver from the outside of the vision system This operation is fundamental for centering the camera s optical axis with the mirror s one Chapter 3 Start using RoboCom Mounting the battery pack The battery pack consists of four batteries and their container Place the batteries in the container in numerical order like shown in the figure and fix them with the belt Plug the power wires in the battery plates like indicated by the labels on the wires Battery Ill Battery a md Battery IV _ Battery l _ m EN Inserting battery pack electronic case and MacMini Now that the battery pac
43. writing an integer value into the PIC PR2 register that can be calculated using the following formula PWM period PR2 1 4 Tosc TMR2Prescalevalue where Tosc is 10 at 40Mhz In our case the PWM frequency chosen is 20KHz To obtain this value we put PR2 TC 16 12410 and a TMR2 prescale value of 74 The duty cycle is the information that a PWM signal carries and it generally varies over time It is the output of the control logic for the power circuit that will drive the motor to the desired rotation speed The PIC18F452 has a maximum PWM duty cycle resolution of 10 bits and its value can be calculated using the following formula5 PWMdutycycle CCPRIL CCPICON lt 5 4 Tosc TMR2prescalevalue where CCPR1L CCP1CON lt 5 4 gt are the registers containing the desired PWM duty cycle value CCPRIL stores the eight MS bits the fourth and fifth bits of CCPICON stores the two LS bits It is important to notice that the PWM duty cycle has to be in the following range PWMdutycycle e 0 PWMperiod as is quite obvious from the definition of PWM duty cycle If the PWM duty cycle equals the PWM period or exceeds it we obtain a constant signal that is always in the high state electrically speaking a constant signal of 5V Having chosen a PWM period of 500 Tosc TMR2prescalevalue we have a 9 bit PWM duty cycle resolution since values that we can write to CCPRIL CCP1CON lt 5 4 gt registers must be in t
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