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2005 Hephaestus Final Report - University of Detroit Mercy ECE

1. A Josh Vetter EE Team Leader l Electrical Team Mechanical Team Gradiat T Reta Elias Brian Cook EN EE Leonard Tomaj TE eae Jean Harris Ono Okagbare Chris Scott Edgar Mabson Figure 4 Team Organization Chart The 2004 2005 Hephaestus teams focus has been on improving the mechanical system completing the electrical system and software algorithms and building a competition ready vehicle Each person was given a primary task as well as additional minor tasks The graduate students were primarily responsible for the image processing and navigation systems A Gantt chart was created and followed in order to maintain a steady schedule and to meet all deadlines A copy of the Gantt chart can be found in Appendix D 1 12 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Many resources were available to aid our team in this design and implementation process The Same resources as well as new ones will be available to aid the coming senior class as well as other future students Mainly the manuals found in the appendices will help as well as product websites Matlab and Simulink help menus books and professors Also professional engineers did help such as Stematt who is a Simulink expert as well as our graduate students The list below in Table 1 indicates which student worked in what system along with their email
2. Convert to T Fuzzy membership function LADAR Output Figure 46 Navigation Algorithm Flow The direction provided by the image processing computer is the input to a Fuzzy Inference system whose output is a fuzzy membership function of possible steering directions The LADAR output which is a 180 map of obstacle locations in front of the vehicle is converted to an equivalent fuzzy membership representation The two sets of membership functions are then fused to produce an overall fuzzy membership function of possible steering directions This membership function is then defuzzified to produce a final steering direction which is the input to the steering control algorithm 3 3 3 1 Algorithm Diagram The overall Navigation System Diagram is shown in Figure 47 This System consists of the Image Processing unit LADAR unit Navigation Controller Drive system and light indicators Each system is broken up into subsystems which will be explained 50 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Pulse y TRIGGER IP Input Steering Output Actual Angle to drive system Drive Output To navigation Image Processing Input Drive Image Processing Input Lights Distance light location in Lights Location Lights Ladar Input Contoroller Navigation Controller Figure 47 Overall Control Simulink Model Figure 48 is the Navigation
3. The circuit of the bandpass is in Figure 27 ER 0 Y2 U3A 1 35 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Figure 28 Full Wave Rectifier MARAP L 1 FREQ 3 0k Hz 7a Hephaestus 2005 The next step in the circuit was the full wave rectifier The full wave rectifier is used to invert all the negative voltage outputs coming from the bandpass filter into positive voltage values Figure 28 shows the circuit schematic of the full wave rectifier The integrator circuit comes after the full wave rectifier The integrator integrates the rectified sinusoid building up output voltage as long as the applied input voltage is positive The stronger the input signal the faster the output voltage will build up helping to block out ambient noise of the same frequency A potentiometer should be used in this circuit to vary the sensitivity of the integrator WAMIPL 10 31 FREQ 3 0kHz The equation A vo RC vo in Figure 29 Figure 29 Integrator ane euaemeee eee eae KC was used to find values for R and C The schematic of the circuit is shown The final circuit to trigger the relay is the comparator circuit is the comparator circuit Once the integrator is built up to the correct voltage the output of the comparator will enable the relay 36 Copyright 2005 University of Detroit Mercy Hephaestus University of De
4. 3 1 3 1 Electronics amp Layout For this year s group the upper platform was one of the few completely new aspects of the mechanical portion of the vehicle It was first designed in Catia Using Catia was a significant help in taking the design through several different changes and variations The team was able to make sure that it worked and all fit together before actually building it and that saved both time and material which were in short supply The final design of the upper platform was very 20 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 functional and visually appealing The design included a space for the judges camera that was covered on all sides except the front This space for the judges camera is linked to the space created for the two computers The place reserved for the two computers is also covered and flows seamlessly from the judges camera compartment The computer compartment is one of the more unique and interesting aspects of the upper platform It keeps both laptops stored one above the other When one wishes to access the computers they each slide out of the compartment on opposite sides When you slide them out you can use the computers while they are still attached to the platform This feature allows for quick adjustments while running the vehicle To keep the vehicle looking forward both the LADAR and the camera are attached to the upper platform The
5. University of Detroit Mercy Hephaestus 2005 4 0 Operation amp Maintenance This section of the report is very critical in that proper steps are taken in order to initialize the vehicle and have a safe maintenance procedure Note that safety is most critical and students faculties should be careful 4 1 Startup Manual As mentioned earlier there are three ways to operate Hephaestus The first is with the Roborun software the second would be with the speed control software with the programming computer the third and final way to move Hephaestus is with a remote controller Note incase of an emergency the best way to stop the vehicle is to E Stop it however in situations where E Stop is not active turn off the controller 4 1 1 RS232 Roborun Utility In the PC utility many of the Roboteq configurations can be set This program is very useful in configuring testing and diagnostics The following are detailed steps in operating the Roboteq controller using its own software run utility The robot should be free standing on jack stands or tools for this type of testing Connect the 55A fuse located on the end of the battery tray Slide the battery tray in the vehicle located on the lower platform Connect the Roboteq controller directly to a PC via RS232 serial cable Launch Roborun software Turn on the controller Make sure the correct comport is active os al Oe ae ee Se Once the controller is connected to the active port o
6. operating properly and due Reset to defaults to the lack of time that was Controler Input Ps 232 F WatchDog Load from Controller available for tes ting the Reset Controller for these changes to take effect Motor Control Mode A Speed B Position i Closed Loop Save to Controller final testing was completed ert a B Analog f Encoder l Load Profile from Disk Save Profile to Disk in open loop Next year s term should be able to Chanel 1 Chanel 2 Input Adjustment Linear Linear solve this problem Change COM LAN Port Estop inv Input Causes Emergency Stop PY ee ee Input E Mode No Action gt Update Controller Sotmare controller Input F Made No Action Settings should be saved to E Figure 19 PC Utility Autonomous Settings The closed loop configuration of the proportional gain integral gain and differential gain shown in Figure 20 is very critical in enabling the robot to move to the desired position Basic knowledge of controls is needed to be able to find the best suitable settings Based on the following knowledge different parameters were configured tested and observed by moving the steering motor a full turn Kp gives a fast rise time and when it is too high the system overshoots Kd eliminates overshoot Ki eliminates steady state error increases response time and rise time The best settings which were determined are as follows which resulted in about a 160 turn Prop
7. 1 Gantt Chart 2 Failure Mode Effects Analysis 3 Contact Information Appendix E Reports Presentations 2004 Hephaestus Report 2005 IGVC Report 2005 IGVC Presentation Appendix F Website Appendix G Photos Appendix H Schematics 4 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 2005 Hephaestus Design Report ABSTRACT The following document serves to detail the conceptual design and physical work completed on the University of Detroit Mercy Hephaestus vehicle platform Hephaestus has served as the platform for a multi year multi discipline effort to compete in the Intelligent Ground Vehicle Competition This vehicle was created in 2004 including initial design and partial construction During the past two term of the 2005 school year the design and construction have been refined and reworked Additionally the control and sensory systems have been implemented It is expected that another multi disciplinary team will continue work on Hephaestus during the 2006 terms This team shall remedy the issues mentioned in this document and prepare Hephaestus for competition in the 2006 Intelligent Ground Vehicle Competition Currently all systems of the vehicle are intact however several are in need of work to allow for proper operation Specifically the greatest downfall of the Hephaestus platform has been the drive train It is expected that the 2006 team should redesign the dri
8. A similar self locking effect in the drive motor allows the vehicle to stay stationary when power is lost or shut off This acts as a fail safe mechanism in case of power outage while climbing or descending a ramp There were a lot of problems with the steering motor The first thing that was done with the motor was changing how it was mounted The decision was made to mount it on a thick bracket that is secured on more than one axis unlike the mount from last year This made sure that the motor wouldn t move The next problem was the steering system had too much resistance The resistance was eliminated by making sure that the main rotating parts were supported by bearing instead of nylon bushings This helped the whole system turn easier making the steering motor adequate when the system was handled gently The chain was the weaker part of the steering system It would have been better if the steering motor had more torque or there was a higher gear ratio Something else that would help the steering would be to reduce the amount of weight on the upper platform for it to turn There were a lot of problems with the motor shaft because of 19 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 its two components The two components would come unscrewed from each other To solve this a hole was drilled through both of the components and a screw was then placed through the holes to hold them in plac
9. Read Value fscanf R n m size Read Value Send Encoder reading Question command Read Ist sent character same as sent if m gt 2 f there is garbage infron clear it xx strcat Read Value 1 m 2 m 1 if min x xx If cleared read next characters ReadValue2 fscanf R Read 2nd Character Encoder Speed ReadValue3 fscanf R Read 3nd Character Encoder position test 1 Get out of loop end end end Speed encoder value reading 127 to 127 A cellstr ReadV alue2 Make Character array cell array SpdEncdr hex2dec A Convert Hex value to dec Steering encoder value reading 127 to 127 B cellstr ReadValue3 Make Character array cell array StrngEncdr hex2dec B Convert Hex value to dec pass 1 StrngEncdr pass 2 SpdEncdr 57 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Matlab doesn t allow to change the values directly to decimal format Each character must be converted to a cell array by using the cellstr command Then the character can be converted from hexadecimal to decimal which will give decimal values Equations maybe added to the m file to convert this value to actual readings Please refer to the Simulink file and the commented code in Appendix C 7 for more details on this section 3 3 6 2 Current Readings To inquiry the controller to return the actual number of Amps being consumed by each motor the M file shown in Figure
10. Take the R C and first move the joystick from one extreme to the next a few times Now move the other joystick from one extreme to the next a few times Now leave the both joysticks in their dead band positions and press the program button Restart the controller RC MODE IS NOW ON Move the joysticks to move the vehicle 4 2 Maintenance Like any vehicle maintenance has to be considered to maximize the vehicles performance and longevity This section lists the maintenance information for various part of the vehicle 4 2 1 Batter Removal and Charging Two main battery sources are provided for Hephaestus one in the lower platform and the other in the upper platform 4 2 1 1 Lower Batteries The one in the lower platform is the bulk of the two Itis two 12V 55AHr batteries connected in series to provide 25V 55AHrs to drive both motors and power the Roboteq controller This battery tray is very heavy and is recommended that two people install it Removing is little easier Figure 63 displays an image of the sliding tray Figure 63 Battery Tray Removal 65 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 1 Locate the bolts that hold the tray in place 2 Remove the wing nuts from the bottom of the bolts and then pull the bolts upward to remove them 3 Carefully pull the tray away from the vehicle completely in a straight line 4 If not planning to use the batte
11. To close Rs232 you wish to close the port then enter the fclose R command NOTE Serial communication ports settings must be as follows 9600 bps 7 bit data 1 Start bit 1 Stop bit Even Parity Table 3 lists of commands used for autonomous operation via RS232 communication Most commands were used in the software which will be discussed in a later section Table 3 Roboteq Commands Set speed or position where M motor channel and direction Toggle available digital output lines on off Query power applied to motors Query amps consumed by motor Query analog inputs Query battery voltages Query digital inputs 30 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 mm Read parameter settings where mm parameter number mm nn Modify parameter where nn desired parameter value FF Apply parameter changes NOTE Consult Roboteq User Manual in Appendix A 1 for more detailed descriptions of commands and reply messages 3 2 1 3 3 Remote Control A radio Remote controller R C is used to navigate the vehicle unto the course The R C used is an FM Futaba ID AZPT4VF 72 This controller has 6 channels of communication although the Roboteq controller is cable of handling only three Since only two channels are required with our vehicle this R C controller is more than sufficient for Hephaestus applications The Roboteq controller has five command control curve
12. and the Receive file runs on the external computer The files are included in Appendix C 8 under the following names gt DataLogTransmit mdl gt DataLogRecieve mdl gt sfun_time dll These blocks are highly configurable and can support any number or type of data streams To add more channels simply modify the Input and Output Data Types within the Pack and Unpack blocks By configuring the UDP Send and UDP Receive blocks the data stream can be designated for a single computer or broadcast to many PCs or laptops It should be noted that using the UDP transmission method and a wireless connection there will be some amount of lost or corrupted data The only way to avoid this is to either use a TCP connection or a wired connection TCP is not recommended for this as it will slow the processing on the control computer Jog E DataLogRecieve JOE File Edit View Simulation Format Tools Help W DataLogTransmit File Edit View Simulation Format Tools Help DiS Hg B 2ce nji oma D Hg eR gt she Figure 58 Data Logging Simulink Files 60 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy 3 3 8 Turn Counter Since the spiral cord in the shaft between the two platforms will loosen and tighten as the vehicle turns it 1s critical to keep track of the number of full turns so that pressure is not put on the wiring This is being taken care of by code in tw
13. encoder Figure 64 Encoder Schematics Table 9 Speed_Encoder Connections Enc Name Color Ethernet Pin Pin Table 1 PCD16 so a E ee ee 5 ChannelA Orange 6 Table 10 Steering_Encoder Connections 5v l A t Kr A Z Enc Name Color Ethernet Pin B ov Pin Table 1 Channel B 020 3 Z Orange White Channel A Make sure that the encoders are damaged by testing them Figure out which encoder is being replaced If speed encoder use table 9 if steering encoder use table 10 Make sure to note these connections are according to bottom view of the encoder Get the encoder and solder according to the respective table Note that these terminals are very delicate and it s possible to break them Make sure to use shrink tubes oo oe ee eS Test the encoders to see if they are working properly 4 2 4 2 Circuit Repair Circuit repair is a delicate process One must make sure that all connections are correct not to destroy the new part or other parts already connected to the circuit board All circuits of Hephaestus reside in the electrical box Before a component or a part can be repaired it must be identified A digital multi meter and or and oscilloscope will do the trick Once the problem has been discovered view all schematics provided and carefully replace the part 68 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 4 2 4 3 C
14. the worst case scenario distance d increases when three extra wheels are added to the three wheel configuration In doing this however the problems that can only come from such a configuration surfaced Since only three points are required to make a plane the drive wheels 16 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 often were not in contact with the ground surface due to inconsistencies in the surface In order to resolve this the idler wheels were lathed so that approximately 0 75 were removed from the diameter of the wheels This allowed for all three of the drive wheels to be in contact with the ground at all times yet still allowed the idler wheels to provide stability in extreme circumstances when needed Figure 8 Three Wheels vs Six Wheels Figure 9 Wheel Pod Schematic The steering motor rotates the entire wheel pod assemblies As seen from Figure 9 the wheel pods have two separate sprockets connected to two separate chain drives The top sprocket connects the drive motor to the vertical drive shaft which in turn drives the wheel through a bevel gear The bottom sprocket connects to the steering motor and in effect serves to turn the entire wheel pod thus orienting the wheels in the direction of motion 3 1 2 3 Battery Tray Design The battery tray shown in Figure 10 is designed to hold two 12v car batteries connected in series It is also required
15. with occasional gaps in the lines Vehicles may cross a line resulting in a point deduction so long as some portion of the vehicle s mechanical footing remains in bounds Figure 2 Image of construction barrel and paint lines Image by Team Hephaestus e The vehicle must be able to negotiate grass sand dirt and a ramp with a maximum 15 grade The sand may be two to three inches in depth These conditions may be dry or wet e The vehicle must travel at a speed of at most 5 mph 7 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 For safety purposes the vehicle requires a wireless emergency stop E stop mechanism and a manual E stop system These systems must bring the vehicle to a complete stop within six feet on inclines up to 15 o The wireless must operate at a minimum of 50 feet away o The manual must be operated by the depression of a one inch red button located at the rear of the vehicle between two and four feet from the ground The vehicle dimensions are as follows o Length between three and nine feet o Width between three and five feet o Height between zero and six feet this does not include an antenna The vehicle must be capable of negotiating an 5 foot turning radius The vehicle may operate on combustible fuel or electric power All vehicles must be safety inspected on a simulation course Each vehicle will be required to carry a 20 pound pay
16. 1 T jo Anal _Stop Cfo Ene a r fo Ot FET Temp Plot 0 fo Bat Volt r Command 2 Motor 2 Stop Iv jo Amps 0 Cir Peak 120 P cl I Plot za Iv jo owa 100 _ _ ___ fo Ana2 J 80 J Joystick Enable Config Joystick 0 a pa m Input Status m Set Outputs E M outc Mio FET Temp 20 eae r OutD T fo Ctrler volt Of ep ae pe fe es e E EStop Inv Communication Error U Ax logging was used in Matlab If for some reason the commands are stopped however the motors are still operating disconnect the cable or turn off the controller 28 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 3 2 1 3 2 Serial Control Autonomous As mentioned earlier configuration can be done in Matlab but it is easier to do in the Run Utility For configuring the controller for Autonomous use it is very important that the motor mode be set A Speed B position since our first motor will be for speed and the second motor is for steering so that once a desired angle is reached the motor will stop Also since an E stop system will be in use make sure to enable it as shown in Figure 19 Note again that the Roboteq should be in closed loop in order to get the feedback from the encoder module however because the vehicle was not Controls Power Settings RrC Ana Specific Close Loop Encoder AL Out Codes Run
17. 42 Sensor and Vision System Integration 3 3 1 Vision System 3 3 1 1 Camera Figure 43 Camera The camera chosen for the Hephaestus is the Uni brain Fire I board camera This camera was selected for its low cost low power consumption and performance The Uni Brain Fire I Board Camera shown in Figure 43 courtesy of Www unibrain com captures the images used for lane and obstacle detection This camera is a single board fully operational Fire Wire color camera capable of 400Mbps data transmission with a native resolution of 640x480 pixels and 80 95 horizontal view angle for uncompressed VGA picture acquisition at 30 frames per second The latest 1394 Texas Instruments chipsets and Sonye CCD sensor provides a high quality subassembly for image capturing The camera provides sufficient image clarity and resolution and connects easily to a laptop via the fire wire 47 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 port provided eliminating the need and extra cost of a frame grabber A plastic weatherproof box was constructed to encase the camera 3 3 1 2 Image Processing Strategy The image processing strategy determines which obstacles potholes and lines are present in the camera s field of view A preliminary direction is determined by examining an image and establishing a preliminary direction between the lane boundaries In order to determine this preliminary direct
18. 56 is The command 2A The simulated question is number returned is an unsigned Hexadecimal number ranging from 0 to 256 Oto FF in Hexadecimal Note that everything in this program aside from different variable names and the command question is the same as the previous diagnostic file in such that three characters are returned where the first is the questions sent and the last two are the speed motor Figure 56 M File Rs232Read_Current function StrMotCur SpdMotCur Rs232Read_Current u global R This query will cause the controller to return the actual number of Amps being consumedby each motor The number is an unsigned Hexadecimal number ranging from 0 to 256 Oto FF in Hexadecimal if R BytesA vailable gt 0 Clear unnecesary data from Rs232 xx fread R R BytesAvailable end fprintf R A test 0 while test 0 Read Value fscanf R n m J size Read Value if m gt 2 f there is garbage infron clear it xx strcat Read Value 1 m 2 m 1 if min x xx If cleared read next characters ReadValue2 fscanf R Read 2nd Character Speed Mtr Current Read Value3 fscanf R Read 3nd Character Steer Mtr Current test 1 Get out of loop end end end Send current reading Question command Read Ist sent character same as sent Speed motor current reading A cellstr ReadValue2 StrMotCur hex2Dec A Make Character array cell array Convert Hex value to dec Steering motor current reading
19. B cellstr Read Value3 SpdMotCur hex2Dec B Make Character array cell array Convert Hex value to dec pass 1 StrMotCur pass 2 SpdMotCur current and the steering motor current respectively 58 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy 3 3 6 3 Voltage Readings Hephaestus 2005 This e query M File shown in Figure 57 will cause the controller to return values based on two internally measured Just as before the will send back 3 voltages controller characters the first is the sent question and the next two are voltages The first voltage is the Main Battery voltage present at the thick red and black wires The second voltage is the internal 12V supply needed for the controller s microcomputer and MOSFET drivers The values are unsigned Hexadecimal numbers ranging from 0 to 255 To convertthese numbers into a voltage Figure formulas described in Internal Voltage MonitoringSensors on page 62 of the Roboteq manual were used function MainBattV Internal Volt Rs232Read_Voltage u This codes sends a character to the Roboteq controller to read the main 24v Yvoltage reading as well as the internal 12v global R if R BytesAvailable gt 0 xx fread R R BytesA vailable end x he fprintf R x Clear unnecesary data from Rs232 if Send Voltage Question command test 0 while test 0 Read Value fscanf R n m size Read
20. Controller Algorithm The Image Processing input is ran through a saturation block where it imposes upper and lower bounds of the input This is then rounded and fuzzified to get possible angles as a direction for the vehicle to drive Goal Angle Hr MATLAB 4 Function Saturation Rounding Function Image Processing Input 7 aa round EN Fused Result Actual Angle f Rounding o dae aini MinMax Function Function t ail Allowed Direction Centoid Lett Outi Ladar Input To Lights Centroid Right Global Minimum Lights Distance location Critical Remap Lights Location Figure 48 Overall Navigation Simulink Model Obstacle Avoidance is implemented using the LADAR to locate obstacle positions The obstacle avoidance system generates a database of distance values referring to obstacle location ahead of the vehicle Figure 49 below is the critical remap block of the LADAR data The minimum input from the LADAR is found and compared to 2000 If the minimum is less than this value 51 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 then the minimum value is subtracted from the original LADAR data If the value is greater than 2000 then the LADAR data is used as is with no remapping Wlinhlax 1 Compare To Constant To Lights Constanti Figure 49 Navigation Critical Remap To create the final angle of travel of the vehicle the goal following informa
21. assembly This allows the vehicle to always face forward so that the LADAR and camera can detect obstacles and determine the best course for the vehicle to drive through Figure 5 Catia 3D Model The platforms are constructed using 30mm x 30mm Bosch aluminum extrusions The skin of the electrical platform was formed out of alumalite Alumalite is a man made material consisting of one corrugated sheet of a polymer plastic sandwiched between two sheets of 14 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 aluminum This material is much stronger and aesthetically more appealing than the sheets of aluminum used prior to the 2005 design 3 1 2 Lower Platform The drive train components including the steering and drive motors are mounted on the lower platform This platform is supported by a triangular wheel pattern consisting of three wheel pods Figure 6 Drive Train Configuration 3 1 2 1 Drive Train Two motors are used to control this vehicle A drive motor controls the speed and a steering motor controls the angular position of the wheels Figure 6 displays an AutoCAD model of the top view of the lower platform The drive chain is shown in blue and the steering chain is shown in red Note that the red chain is wrapped around the center shaft which causes the upper platform to rotate with the wheels Refer to the 2004 Hephaestus report P28 3
22. dirBPulse get as integer value if dirB lt 16 Convert to hex commented very well and all three SteerB cat 2 0 dec2hex dirB a else SteerB dec2hex dirB m files are very similar Only one end command cat 2 wordB SteerB roboteq character format motorB speed m file will be clearly explained the if R BytesAvailable gt 0 Clear unnecessary data from Rs232 Rs232Read_Steer_Pos m file xx fread R R BytesA vailable end When the Navigation angle outputs _ fprintf R command Send the character out using Rs232 a positive non zero this block is te dea x dirB simulated The u is the input of this Matlab function which is the angle Figure 53 M File Rs232Read_Steer_Pos 55 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 and x is the output mainly only used for the display Since the RS232 is throughout specify this is a global parameter R Specify which motor command is addressed A specifies the speed motor in the positive direction Convert the desired speed to a hexadecimal value For this example 30 will be 1E command cat 2 wordA speedA basically puts the values together as AIE The next part of the code basically reads any flawless unnecessary data from the RS232 so that is doesn t interfere with the messages sent This part of the code is used throughout all the programs and should be executed before sending the me
23. driven manually while serial port control is the mode implemented using the PC based utility and during autonomous operation Please visit the Roboteq website www roboteg com to download up to date software and for technical support 26 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy 3 2 1 3 1 Serial Control Run Utility Hephaestus 2005 Although testing and configuration can be accomplished in Matlab the PC run utility makes it much easier to configure and test the controller Figure 15 displays the main controls screen Once the controller is connected to the serial port of the desktop the controller info should display valid ID Rev and codes If nothing happens try exiting the program and opening it back again Note that if you actually plan on using this software for testing the robot should be free standing on jack stands or stools Note that a regular RS232 cable should be connected directly from the controller to a PC lRoboteQ Controller Configuration Utility V1 7 02 01 05 Controler Input Motor Control Mode Input Adjustment EStop inv Input Input E Mode Input F Mode m Controller Info COM1 Active Controller not found Controller ID No Data Software Rev No Data Hardware Code No Data No FET Info No Amp Info Encoder ID No Encoder Info Controls Power Settings R C Ana Specific Close Loop Encoder RC Out Codes Run Reset to d
24. er Bor ow 24 RS Creel Ss forint ie FY 25 Pel chee commecthon AUX chip mR c c7 Robowsg compolier pins torier oeme gt o o o o o S Coide phs pues bo lbi r DES obied 0 0 TO TO T T 23 LED obrac indicator i 30 CADAR powenkdam commoniostier C cooo tt 3t EED obstacle diosa ta c o o a ce Caia Sed Fide Peer ceed O T tat eh k uly T es a a D 39 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Figure 35 R C Receiver Figure 35 below shows a schematic of the R C receiver The R C receiver is connected to part label 24 and 25 on Figure 34 Figure 36 shows the wiring diagram for both the manual amp wireless E stop system Figure 36 E Stop Manual and wireless 40 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Figure 37 and Table 5 show the Roboteq controller pins which are converted to an Ethernet connection These pins are routed through the central shaft via a spiral Ethernet cable and connected to the electrical box This is done for two reasons First the control computer must send signals to the Roboteq controller which is located in the lower Pin Wire Color platform The spiral Ethernet cable is used to avoid the cable being 1 stretched and snapped during the upper platform being rotated They are color coded to match the Ethernet cable Figure 37 shows the
25. last part of the upper platform is the mast It is a basic feature but it is important The LADAR had to be shared between the two vehicles as it is such an expensive piece of equipment It needed to be able to be swapped very quickly as there may not be much time between runs of the two vehicles To accomplish this the LADAR had to be mounted in the same way on both vehicles There would not be time to significantly modify how it is attached between runs On the LADAR are two brackets that connect to two RexRoth 30mm Aluminum pieces These aluminum pieces hang down vertically The bracket slides down over them and then they can be fastened in place This is done with a threaded piece that tightens against the aluminum in a way similar to a set screw Both vehicles were able to use this method A swap can be made between the vehicles in just a few seconds For this vehicle the LADAR had to be attached to the upper platform to keep it facing forward at all times To keep it low enough the vertical aluminum pieces were hung over the edge of the top platform This not only lowers it but keeps it out of the way of other components on the top platform To get a better idea of how the LADAR is mounted please refer to Figure 12 Figure 12 LADAR Mount 21 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 All the electronic components are integrated to one central unit the electrical box The e
26. reaction time 9 Reverse In the event that the vehicle drives into a trap as seen in Figure 3 it must be able to go in reverse if it does not have a 0 turning radius f fe f I Figure 3 Diagram of possible obstacle traps on IGVC course Image from IGVC org 10 Modularity In the event of failure or damage at the competition easy exchange of key components within the five minute window between runs will be crucial The LADAR 10 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 must be shared with other UDM teams The mounting system must be designed around this 11 Mechanical Reliability Designs that include mechanical systems that are prone to failure must be avoided 12 Mechanical Manufacturing Designs that include mechanical components that will be difficult and time consuming to manufacture must be avoided 13 Ease of control An intuitive and reliable method of controlling speed and direction should be incorporated in the design of the vehicle 14 Cost Due to the fact that this is a budgeted project the cost of potential designs must be weighed against their functional advantages 15 Design Ingenuity The quality and creativity of the design will determine the success in the design competition of the IGVC Therefore aesthetics of design will be nearly as important as functionality Adherence to the Intelligent Gro
27. set up with a resistor ratio to produce 3 5Hz frequency The 555 timer enables the lights to blink at a continuous frequency whenever a light is turned on Making the lights blink at a controlled frequency make them easily observable The circuit setup for the lights is illustrated in the following Figure 50 The Simulink program that controls the light is made up of a few Matlab function switching and logic blocks The file is then merged into the navigation program and is fed as an input whenever the LADAR transmits information Please see Appendix C 6 for the software files 3 3 5 Speed Steering Control Figure 51 Steering Speed Control Flow Chart The purpose of the control software is Navigation Output to be able to command the Roboteq gt Turn Angle controller to steer the desired angle and No Angle 0 to slow down where necessary The Tum navigation angle is the input for the a suman T Speed Motor On i Speed HIGH steering and speed system as shown in Convert to Hex Appendix C 1 The flowchart of how aaa A Speed LOW Speed LOW the control system operates is shown in Figure 51 The speed control is based Steering Motor On Negative Steering Motor On Positive Steer Nav output steer Nav output on a two speed strategy If it is Convert to Hex Convert to Hex determined by the navigation al
28. single color camera and a laser distance sensor to obtain information about its environment Using this information image analysis and a fuzzy logic based navigation strategy are implemented in a Matlab Simulink environment running on a laptop PC Using the resultant navigation output steering amp speed commands are executed via a laptop PC controlling the dedicated motion controller 3 1 1 Vehicle Architecture The chassis of the Hephaestus vehicle shown in Figure 5 is composed of two octagonal shaped platforms with the lower one supporting the mechanical components i e chain and sprocket drive system and the upper supporting the electrical components 1 e laptops power and control boxes These two platforms are connected via a hollow shaft that also functions as a raceway for wires which power most of the electrical systems including the camera The camera is mounted on the highest point of the vehicle mast The vehicle is supported by three pairs of wheels arranged in a triangular pattern In each pair of wheels one is driven by the motor while the other wheel serves to improve stability of the vehicle The electrical platform is slightly smaller than the mechanical platform The mechanical platform has a width of 38 in at the shortest section which complies with the dimension criteria set forth by IGVC The upper platform housing most of the electrical systems 1s designed to rotate about the center shaft synchronously with the wheel
29. team had a hard time finding the right amperage so as a result two MEH 17 series hollow shaft micro encoders from Microtech Laboratory Inc were chosen and are connected to the shafts of the steering and drive motors They provide accurate speed and direction feedback to the controller These controllers draw 30mA each and have a resolution of 300 pulses per revolution Refer to the Roboteq manual in Appendix A as well as the spec sheet in Appendix B 3 for any Encoder questions reference 3 2 3 E stop Safety is a major issue in the IGVC competition There is a chance that vehicles will go off track and possibly hurt someone The safety features that must be implemented are the manual emergency stop and the wireless emergency stop On the Hephaestus vehicle both of these safety features are present 3 2 3 1 Manual E stop The controller that is being used on the vehicle has a built in emergency stop pin When that pin is driven low then the emergency stop is activated For the manual e stop team Hephaestus uses a push button that acts as a normally open switch When this button is pressed pin 15 which is the emergency stop pin on the controller goes low and the e stop is activated The manual configuration is actually connected using an Ethernet connection This helped us to transmit the data that the e stop was being pressed to the power box a2 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestu
30. to the Roboteq and then reading back what the controller sends back Note that all the m files discussed are exactly the same aside from the question command and maybe a conversion equation Please refer to the Simulink file and the commented code in Appendix C 7 for more details on this section 3 3 6 1 Encoder Readings The M file for the encoder reading is shown in Figure 55 It is very important to read the speed and position computed by the encoder module Sending the command K to the controller will ask the question and then 3 characters will be sent back The first fscanf R will return the question the second fscanf R will return the hexadecimal number speed reading for the first encoder and the third fscanf R will return the hexadecimal number position reading for the second encoder Note that the while loop is there to make sure that all three data points are received and there 1s no error Figure 55 M File Rs232Read_Encoder function StrngEncdr SpdEncdr Rs232Read_Encoder u global R This mfile sends a question to the encoder module to find out what the speed reading is The module will return 3 characters The question encoder reading amp Encoder 2 Reading The values are signed Hexadecimal Ynumbers ranging from 127 to 127 x k if R BytesA vailable gt 0 Clear unnecesary data from Rs232 ifany xx fread R R BytesAvailable end fprintf R x test 0 while test 0
31. vehicle stable Without stability the vehicle has no functional guarantee In the 2004 design two major calculations were performed to assure stability center of gravity and incline calculations The center of gravity was calculated as y axis 0 00 x axis 0 96 Z axis 17 00 The equation used to solve for these values is Total Weight CG 2 Individual Weight Individual CG equation l where total weight refers to the total weight of the vehicle CGr refers to the center of gravity of the entire vehicle individual weight represents the weight of each component on the vehicle and individual CG refers to the lateral location of the center of gravity of each component Please refer to the 2004 Hephaestus report P18 20 in Appendix E 1 for more information and calculations 24 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Note that the main features of the Hephaestus which improve stability is the three wheel configuration using two wheels in one wheel pod and the battery tray being the heaviest item being in the center of the lowest point of the vehicle Table 2 Weight breakdown 3 1 5 1 Mass of Vehicle The 2004 estimated the vehicle weight would LowerPlatform 10 Middle Platform 6 be about 250 Ibs however the final weight of Upper Platform Le Upper Housing O the vehicle is now estimated to be about 355 Dive Motor shaft lbs Table 2 below wil
32. 0 in Appendix E 1 for more information on the drive train design The idea behind the drive train is relatively simple The idea is to have a single motor drive three different shafts with a two to one ratio The three shafts will then drive three other shaft perpendicular to them driving the wheels This is the idea that was used for the setup of the drive system However it did not end up quite this simple The final drive train setup had the motor driving a shaft single shaft through chain This single shaft was connected to the drive shaft in the three wheel pods via a different chain There was a two to one ratio between the drive shaft in the pods and the drive shaft that was connected to the motor Each shaft in the pods was connected by bevel gears to a shaft perpendicular to the drive shafts The wheels were then connected to these shafts There was also a tensioner on the chain in an effort to keep the drive chain from skipping on the gears under acceleration and to dampen chain harmonics 15 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 The pre existing design of the chain and sprocket system did not work because it created slack in the chains and never fully engaged each sprocket To improve upon this design an idler was removed the chain was rerouted and a chain tensioner was added A drive shaft was then put into place to connect the chain to the motor This drive shaft the
33. 05 5 0 Critical Evaluation of Design While the theory behind the Hephaestus vehicle is solid there are several problems that need to be addressed in the current design The vehicle did enter the IGVC competition however it did not even try to qualify because of major issues with the mechanical system which will be discussed shortly The vehicle actually did perform autonomously inside a made up course inside the tent on sold ground for about 5 minutes Once it got on the grass the steering motor was destroyed due to the excessive torque The first and the most critical of these is the chain and sprocket system Too much time was wasted on this aspect of the vehicle without a satisfactory solution A critical factor that dictates the success of most chain and sprocket systems is whether or not the sprockets in the system are level with each other If the sprockets are not leveled then the chain is less likely to be properly tensioned The chain not being able to fully engage the teeth on the sprocket will become misaligned and slip off the sprocket Rather than eyeball the height at which each sprocket is set on the shaft a sufficient leveler could be used to level the sprockets or spacers machined with identical dimensions could be mounted in between each sprocket on the shaft to ensure that chain will not be misaligned To remedy the problem of the chain not being able to fully engage on the sprocket the chain was tightened Tightening the cha
34. 1 Battery Removal amp charging 65 4 2 1 1 Lower Batteries 65 4 2 1 2 Upper Batteries 66 4 2 2 LADAR Swap 66 4 2 3 Reloading Code 67 4 2 4 Replacement of Parts 67 4 2 4 1 Encoder Replacement 67 4 2 4 2 Circuit Repair 68 4 2 4 3 Chain Sprocket Motors 69 5 0 Critical Evaluation of Design 12 6 0 Component Cost amp Info 72 2 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 7 0 Conclusion 72 APPENDICES Appendix A Manuals 1 Roboteq Manual 2 Roboteq Quick Start Manual 3 LADAR Manual Appendix B Spec Sheets 1 DeWalt Drive Motor Spec Sheet 2 AME Steering Motor Spec Sheet 3 CUI Optical Encoders Spec Sheet 4 Camera Spec Sheet 5 Wheels Appendix C Software 1 Overall Simulink File 2 Image Processing Algorithm Simulink File 2M Image Processing Algorithm m files 3 LADAR Simulink File 3M LADAR m File 4 Navigation Algorithm Simulink file 4M Navigation Algorithm m files 5 Speed Steering Control Algorithm Simulink files 5SM Speed Steering Control Algorithm m files 6 Obstacle detection LED Display Simulink files 6 Obstacle detection LED Display m files 7 Diagnostic Simulink file 7M Diagnostic m files 8 Data Logging files 9 1 Encoder_Counter m file 9 2 Angle Counter Simulink File 9M Angle Counter m File 10 Data Link files 3 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Appendix D Other
35. 14 Black Wire B 1 B 3 Red Wire 12 V power supply C 7 Yellow Wire Table 4 E Stop wiring 33 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 B 1 and B 3 have to be jumped together with one lead then going to the 12 V power as seen in Figure 25 below which is the back panel of the receiver component Figure 25 RF E stop pin connections 3 2 3 3 Audio E stop In previous years there was a threat of the RF e stop not working because of electromagnetic interference With this in mind the idea of building an audio emergency stop was thought of The audio e stop has 7 blocks which include an audio amplifier with microphone a bandpass filter a full wave rectifier an integrator a comparator and a latching relay The sound source that was used is an athletic whistle with a 3 0 kHz frequency When the sound source is activated it will go through its various blocks of the whistle stop circuit The first block of the whistle stop circuit is the audio amplifier This year the audio amplifier configuration that was used is the Jameco Super Snoop big Ear This audio amplifier uses various resistor capacitor configurations a 9V battery and 2 integrated circuits to provide its functionality The two integrated circuits that are used are the LM1458 and the LM386N 1 The LM1458 is a general purpose dual operational amplifier and the Lm386N 1 is a low voltage audio power a
36. Read_Steer_Pos u according to the gear ratios and tire Slows down vehicle and turns in the right direction according to input angle global R diameter however we ended up Convert numerical representation of Low speed to hex character and send via using values that gave us the Yoserial port to Roboteq Controller along with the specified motor character wordA A Specifies channel A Speed Motor approximate speed A speed of 30 spdA 30 needs to be positive integer if spdA lt 16 Convert dec value to hex gave us a low speed speedA cat 2 0 dec2hex spdA else speedA dec2hex spdA end command cat 2 wordA speedA roboteq character format motorA speed All the software consists of a if R BytesA vailable gt 0 Clear unnecessary data from Rs232 Simulink file and m files for the xx fread R R BytesAvailable end control algorithm which can be fprintf R command Send the character out using Rs232 found in Appendix C 5 Note that convert steering angle to position representation of 0 127 and then to hex character send via serial port to Roboteg Controller along with the the code is very well commented specified positive steering motor character wordB B Specifies channel B Steering Motor fprintf R Q1 Reset Steering Encoder Counter 2 3 3 5 2 Control m Files PDeg 0 8 300pulses 360 degrees f f dirBPulse u PDeg Angle PDeg desired position 0 127 The code in Figure 53 is dirB round
37. UNIVERSITY OF DETROIT MERCY University of Detroit Mercy College of Engineering and Science Electrical amp Computer Engineering Department Mechanical Engineering Department Detroit Michigan EE Design EE 401 403 Prototype ME 493 Date of Submission August 12 2005 Electrical Engineers Mechanical Engineers Grad Students Ryan Davis Chris Collins Bryan Grider Reta Elias Brian Cook Lei Wang Ono Okagbare Jean Harris Chris Scott Edgar Mabson Leonard Tomaj Josh Vetter Faculty Advisors Dr Mohan Krishnan Professor of Electrical Engineering Dr Sandra Yost Associate Professor of Electrical Engineering Dr Nassif Rayess Assistant Professor of Mechanical Engineering University of Detroit Mercy 2005 Hephaestus Final Report Outline Abstract 1 0 Introduction 1 1 Problem Statement 1 2 Project Requirements IGVC Rules 1 3 Performance Specification 2 0 Design Planning Team Organization 2 1 2003 2004 Team Development 2 2 2004 2005 Team Development 3 0 Vehicle amp Subsystems Description 3 1 General Vehicle Overview 3 1 1 Vehicle Architecture 3 1 2 Lower Platform 3 1 2 1 Drive Train 3 1 2 2 Wheels 3 1 2 3 Battery Tray Design 3 1 2 4 Motors 3 1 2 4 1 Drive Motor 3 1 2 4 2 Steering Motor 3 1 3 Upper Platform 3 1 3 1 Electronics amp layout 3 1 4 Mast 3 1 4 1 Communication between platforms 3 1 4 2 Camera tower 3 1 4 3 Wireless router tower 3 1 4 4 E stop LED Mount 3 1 5 Stability 3 1 5 1 Mass of Vehi
38. Value Read 1st sent character same as sent if m gt 2 xx strcat Read Value 1 m 2 m 1 if min x xx Read Value2 fscanf R Read Value3 fscanf R test 1 end end end f there is garbage in front clear it lf cleared read next characters Read 2nd Character Main Voltage Read 3nd Character Internal Voltage Get out of loop Main Battery Voltage Should be about 24 V A cellstr ReadV alue2 Make Character array cell array to able conversion Convert Hex value to dec Convert dec value to voltage value MBattV hex2dec A MainBattV 55 MBattV 256 Internal Battery Voltage Should be about 12 V B cellstr Read Value3 Create Cell array to able conversion IBattV hex2dec B Convert Hex value to dec Internal Volt 28 5 IBattV 256 Convert dec value to voltage value pass 1 MainBattV pass 2 Internal Volt Figure 57 M File Rs232Read_ Voltage 59 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 3 3 7 Data Logging The Hephaestus vehicle platform makes use of the onboard wireless router to provide external monitoring and data logging This is accomplished with the use of two Simulink models shown in Figure 58 and an associated dll file This method transmits the data using a User Datagram Protocol UDP which is not as reliable as TCP however it requires less processor time The Transmission file operates within the Control computer
39. address incase further help is needed given that the other available resources are not enough Table 1 System_Contact Person Major System Task Josh Vetter Computers joshyjv yahoo com Data Logging Reta Elias Speed Steering control Rere0282 aol com Diagnostic Software Roboteq Encoders Leonard Tomaj RC Controller tomajl sbcglobal net Electric Box Power System oe Davis Roboteq ryan_ eee mer hotmail com ome eee Camera Navigation ME s Drivetrain Motors ME s Catia Drivetrain ME s Platforms Drivetrain ME s Battery Tray Drivetrain var_1097 yahoo com 3 0 VEHICLE amp SUBSYSTEMS DESCRIPTION 3 1 General Vehicle Overview The main design features of Hephaestus are its two platforms and its three articulating wheel hubs that turn simultaneously to produce a zero turn radius In this manner the vehicle can translate in any direction allowing for absolute freedom of movement The design of the wheel assemblies will be described in detail later but the important feature is the mechanical coupling throughout the drive and steering systems Two gear motors run the driving and steering functions of the vehicle As a result a relatively simple motion controller with two input and two output channels could be used to effectively control the speed and direction of the vehicle 13 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Hephaestus uses a
40. al components were not originally designed very well and that is where most of our problems were Next year s team needs to make major mechanical changes because minor ones will not improve the design All the software and electronics were completed however there was almost no testing done in terms of running autonomous at all due to the time constraints and things breaking apart For future teams give the Electrical Engineers plenty of opportunity to test Even if the vehicle is not complete there are many ways to test its components Set aggressive goals and make sure everyone has an assignment with a clear deadline The sooner you break the machine the sooner 72 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 you can fix it testing is absolutely critical Make sure everyone can operate the vehicle not just the Electrical Engineering students 73 Copyright 2005 University of Detroit Mercy Hephaestus
41. al processing speed Image Processing the system bottleneck runs on a dedicated machine while all other control algorithms operate on a separate computer Since the flow of data from the IP computer to the Control computer is of the utmost priority it operates via a TCP link over a LAN connection Both computers are physically connected to an onboard router to make the physical connection Two Simulink models are used to pass the data and each model has an associated dll file These files are included in Appendix C 10 with the following filenames gt TCPServer mdl gt matser dll gt TCPClient mdl gt matcli dll Shown below in Figure 41 are the two models conFigured to pass the Image Processing angle from the IP computer to the Control Computer TCPClient File Edit View Simulation Format Tools Help Da ed a S IP ANGLE 5 Funection Figure 41 Data Passing TCPClient mdl operates on the IP Computer and the IP ANGLE block should be connected to the output of the IP system Within the matcli block the IP address for the destination computer can be set In the TCPServer model the matser block should be set with the port corresponding to that of matcli The Display block will show the current angle and the output block should be linked to the Navigation system 45 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 3 2 6 1 Image Processing Computer The Image Proce
42. aries the program determines the optimal direction by comparing the current image to the most immediate archived image in which the solid lane line appears and extrapolates the expected lane from this previous image Based on heuristics logic this preliminary direction is set and passed to the navigation software There are two main programs used to control and interface the image processing procedure which can be found in Appendix C 2 gt IP_FW m gt framePocess m The first IP_FW m is responsible for communicating with the camera The code initializes the camera by telling it when to capture an image It also defines an object where the images are buffered before being processed Once the buffer has images in it the latest image is passed to the program called framePocess m This program begins by choosing the most recent image from the buffer defined in IP_FW m Once through the procedure described above frameProcess m generates the desired angle of destination This angle is then passed back to IP_FW m IP_FW m then passes the angle to a global variable accessible by the navigation algorithm It is worthwhile to mention that the interaction between the image processing and navigation algorithms is asynchronous When the angle is passed to the global variable by IP there is no flag telling the navigation that there is a new angle The navigation has no way of determining the age of the angle within the variable 3 3 2 LADAR System T
43. cle 3 2 Electrical System 3 2 1 Motion Controller 3 2 1 1 Selection Process 3 2 1 2 Roboteq Capabilities 3 2 1 3 Hephaestus Roboteq Configurations 3 2 1 3 1 Serial Control Run Utility 3 2 1 3 2 Serial Control Autonomous 3 2 1 3 3 Remote Control 3 2 2 Steering amp Drive Encoders 3 2 3 E stop 3 2 3 1 Manual E stop 3 2 3 2 Wireless E stop 3 2 3 3 Audio E stop l Hephaestus 2005 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 3 2 3 3 1 Problems 37 3 2 3 3 2 Suggestions Recommendations 38 3 2 4 Electrical Box 38 3 2 5 Power System 42 3 2 5 1 Lower Power Distribution 43 3 2 5 2 Upper Power Distribution 44 3 2 5 3 Battery Life 44 3 2 6 Computers 45 3 2 6 1 Image Processing Computer 46 3 2 6 2 Navigation amp Control Computer 46 3 3 Sensory System amp software 47 3 3 1 Vision System 47 3 3 1 1 Camera 47 3 3 1 2 Image Processing Software 48 3 3 2 LADAR System 49 3 3 3 Navigation Strategy Autonomous Challenge 50 3 3 3 1 Algorithm Diagram 50 3 3 4 Obstacle Detection 52 3 3 5 Speed Steering Control 53 3 3 6 Diagnostic software 56 3 3 6 1 Encoder Readings 57 3 3 6 2 Current readings 58 3 3 6 3 Battery Voltage Readings 59 3 3 7 Data Logging 60 3 3 8 Turn Counter 61 3 3 9 Navigation GPS 62 4 0 Operation amp Maintenance 63 4 1 Startup manual 63 4 1 1 Rs232 Roborun 63 4 1 2 Matlab autonomous 64 4 1 3 Remote Control 64 4 2 Maintenance 65 4 2
44. colors of all wires in Ethernet cable Table 5 shows to what pins or NO on ff W PDP control lines each wire 1s connected to 00 Figure 37 Ethernet Pins Table 5 Ethernet Connections DB15 to Ethernet converter a Input Ethernet Output Signal Description pins Wire Color Output Be C AE C 2A pee U Sa EALO I aa oo a 6 Pwrin Ground 7 o g mA 7 Pwrin S V5 a Connect to pin 14 Input R C Ch 3 R C radio Channel 3 pulses ue Sue ce 2A Accessory Output Low Current Accessory Output Output D Output D Controller ground Eee a Fe 5V Pwr Output 100ma max _ A 4 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Figure 38 illustrates the diagrams of all four ether net jacks that connect to the electrical box Ground Ground RC RS232 Analog In 1 RC RS232 Analog In 2 E Stop RIC Ch 2 RAC Chl RIC R3232 Data a ii 24V LADAR Power Si E LADAR Ethernet Connection Ground Ground Ground E Stop Connection E Stop Connection 12 Fan 12V Router 12V Camera RACH R3232 Data In RAC R3232 Data Ont CAME Ethernet Connection CTRL O Ethernet Connection Figure 38 Ethernet jacks on Electric Box 3 2 5 Power Systems Hephaestus is composed of two completely independent power systems The first provides power to the motors and controller and is located on the lower platform The Second provides power to t
45. e This didn t last very long as the screw was eventually sheared The next solution was to make the shaft out of one piece This worked but because of the amount of tension on the steering chain the motor output shaft started to bend excessively To counteract this a bearing was placed to hold the part of the motor shaft that sticks through the motor mounting bracket This kept the shaft from bending However the fact that the shaft was bent for so long caused excessive wear and stress in the shaft giving it a short life and causing it to fail at the competition To make things easier for the steering motor and to create longer life for the steering motor either the gear ratio between the motor and the rest of the system needs to be changed or have a stronger steering motor or reduce the amount of effort needed to turn the vehicles upper platform and the wheels Figure 11 Electrical Component Layout 3 1 3 Upper Platform The upper platform also known as the electrical platform houses all the electrical components excluding the Roboteq controller A layout of these components is displayed in Figure 11 They are Vision Computer Control Computer Power Distribution Box Batteries Router LADAR and the payload required by the IGVC This upper platform has been designed in way that it rotates concurrently with the wheels This means that the LADAR and the camera are always facing the direction in which the vehicle is moving
46. e 33 Unity buffer as input on inverter circuit 3 2 3 3 2 Suggestions Recommendations The audio e stop design presented in this documentation is a model for the whistle stop that will be built for next year s competition It is a roadmap that the team can use for future whistle stop projects All of the blocks used here will be used in the whistle stop design but the components value will vary and there may be extra things that next year s team would like to add in order to make the audio e stop better A suggestion that was not able to be implemented with this year s team is getting a DTMF generator for the sound source This will help to cut out other frequencies better because there are two distinct frequencies With this suggestion there will have to be a dual channel bandpass filter that will have to be designed 3 2 4 Electrical Box The electric box power box controls power to the LADAR camera and router Just as an important feature is that it also integrates all the electrical components to one central unit providing LEDs to indicate system power up and communication In simple terms the electrical box does the following e Allows the control computer to plug directly into the electrical box via serial data cable o This means that the control computer can directly drive both motors form this connection e Jt transfers the signal to the Roboteq controller as well as providing an LED to indicate serial data communication e It
47. echanical problem associated with this project With the time constraints that may be involved in next year s project it should be a priority to have 24 7 access to vehicle lab and machine shop along with access to tools and a constant sufficient supply of materials to limit the possibility of exhausting that supply 71 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 6 0 Component Cost amp Info Table 11 provides a detailed retail cost and team cost of the components Incase more parts are needed or supplier needs to be contacted info is available in the table for the majority of the parts Table 11 Steering_Encoder Connections Retail Team __ Component Cost cost Supplier Part Supplier Motor Shaft 23 23 Robot combat Dustin DCW SHO1 8 www robotmarketplace com IPLaptop 1200 SOT HP f wwwhpeom o O Control Laptop 2 500 2 000 IBM______ wwwibmceom 87 Camera 100 100 Unibrain wwwunibrain com 100 Various Remote control 101 101 Futaba DMR 202 gt Esopo f sol sofen o o Structural material 1 300 680 Bosh o o o oO Wheels 6 drive train 900 Various Miscellaneous mech _ 300 200 Various J o ooo o o TETE E E SSCS 7 Conclusion Hephaestus is a very unique design It has unique features such as the integrated controller which simplifies wiring and troubleshooting Unfortunately the main mechanic
48. efaults Load from Controller Save to Controller Load Profile from Disk Save Profile to Disk Prceeccscccccesssscccsccsssocsees RS 232 TO M atchDog Recccccccccsccccesecccccceseestes Reset Controller for these changes to take effect JA and B Speed Separate Closed Loop Chanel 1 Chanel 2 Linear X Linear X Change COM LAN Port No Action COM1 is selected No Action Update Controller Software Exit Figure 15 PC Utility Controls If testing the controller using this software make sure the control input is set in RS232 and motor channel A amp B as speed separate This implies that both motors will keep going until manually stopped If the system is run in closed Controls Power Seinas R C Ana Specific Close Loop Encoder RC Out Codes Run loop the encoder feedback is considered For oe safety reasons start with open loop since many ot e problems arose when in closed loop due to ame a Loni Pie ton Dis problems with the encoder which will be _ ae aa Change COMAAN Pot discussed later Once configurations are set to the desired settings click to Save to controller COM1 is selected Update Controller Software Figure 16 PC Utility Power Settings The next tab shown in Figure 16 enables to set power settings At first not much change was done to this configuration however when testing we decreased the acceleration at times w
49. efore the middle of the competition that the camera could not see over the front of the vehicle If the vehicle were to be used next year there are two other issues that I believe should be addressed The lower platform is still made out of Aluminum and is bending severely in several places This would have to be replaced for any future competitions Also it is our belief that the chain could be replaced If the chain were to be replaced it could be replaced with a larger chain which would also allow for larger gears This would also help the chain slipping issue and could even possibly allow for the current chain and sprocket set up to remain with larger gears to match the new chain of course After seeing the course the size of the vehicle must be reduced by at least a third We learned we need to put the camera to the front of the vehicle as opposed the center of the vehicle Do not use chain excessively When designing the vehicle remember that the vehicle will probably be heavier than you plan and will encounter non ideal conditions Motors should be over specified The frame should also be very strong Remember that you will have to work on this thing and that easy access is important We had a very tight and cluttered chain set up that is difficult to work with in a timely manner The availability of tools and supply of materials 1 e bolts screws structural materials was lacking and almost seemed to be as big as any electrical or m
50. ew over the front portion of the upper platform A picture of this can be seen in Figure 14 3 1 4 1 Communication Between Platforms The only communication needed between the top and the lower platforms is the connection between the Roboteq controller and the control computer This connection is made with a retractable Ethernet cable One end of the cable is connected to the LAN port on the control computer and the other end is spliced and soldered to a 15 pin db15 serial connector which interfaces with the Roboteq controller 3 1 4 2 Camera Tower Figure 14 Mast The camera tower is constructed from the same 30mm x 30mm Bosch aluminum extrusions used for the structure of the upper platform and most of the vehicle As can been seen in the picture of the picture of the vehicle the camera mast is mounted on the frame of the computer housing The camera mast stands between the payload space and the computer housing with a cross bar on the top just below six feet The cross bar is about two feet in length and is centered on the mast to provide a view free of obstruction from the power box or other components on the upper platform The camera is attached to the crossbar using a center plastic holder that is screwed to the end of the crossbar The center plastic and the camera enclosure holder are both taken from a digital camera tripod mount 3 1 4 3 Wireless Router The two computers are linked together using Ethernet cables This se
51. f the desktop the controller info should display valid ID Rev and codes If nothing happens try exiting the program and opening it back again 9 ConFigure the setting to RS232 10 Setup the motor controller to the desired settings as described in section 3 2 1 3 1 63 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 NOTE THAT THE E_STOP IS NOT ACTIVE IN THIS COMMUNICATION SETUP SINCE THE ELECTRIC BOX IS NOT CONNECTED TO THE CONTROLLER 4 1 2 Matlab autonomous Note that testing can be done from a desktop PC just as mentioned in the last section where the controller is connected to the PC but running in Matlab rather than the Roboteq utility However in this section the autonomous startup manual will be discussed where the onboard laptop is doing the controlling These steps assume that configuration settings mentioned in section 3 2 1 3 2 are all set ee a Se ee ee ee Connect all connection to the power box located on the upper platform Connect the 55A fuse located on the end of the battery tray Slide the battery tray in the vehicle located on the lower platform Connect the control computer to the electrical box via RS232 serial cable Turn on the electrical box Turn on the Roboteq Controller Open Matlab and launch the main Simulink file in Appendix C 1 Run the Rs232 initialization commands Run the Main Simulink program 10 To stop this program either hit t
52. gorithm aioe end to Robotq that the vehicle is to be turned the Roboteq controller is commanded to operate in a low speed mode High speed mode is initiated when no turns are required Note that the Roboteq controller has built in speed and position control capability so the steering and speed system have only to generate the appropriate command signals When an angle is given by the navigation it is important to now if this angle iS a positive or a negative to know what command should be outputted The following is an example of the commands according to direction la gt will drive the speed motor to drive backwards A gt will drive the speed motor to drive frontward 53 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 lb gt will drive the steering motor to turn to the left direction B gt will drive the steering motor to turn to the right direction Note that channel A is connected to the speed motor and since our vehicle is omni directional there is no need for backward speed motion However the steering motor channel B is critical and should only move right when given a positive angle 3 3 5 1 Simulink Block The Simulink block in Figure 52 acts exactly as the discussed flow chart There are 3 switches to determine if the angle is zero less than zero or greater than zero Note that originally this was done using if then blocks which performed ok when running with co
53. hain Sprocket amp Motors To Remove 1 2 3 Remove upper platform and all unnecessary obstructions for access to motor area Undo all necessary electrical connections Remove chain find and remove clip on the master link with a pair of pliers 4 Remove Sprocket loosen setscrews that attach it to the motor s output shaft Remove key from the motor shaft s keyway use the correct size gear puller to remove the sprocket from off the shaft repeat this procedure for any sprocket in the drive or steering systems 5 Remove all components used to mount the motor in place 6 If desired replace the motor s output shaft To Replace 1 2 Re mount the motor to its previous location by affixing it to the platform with all the mounting components that were removed Re mount the sprocket to the motor shaft make sure the key has been inserted into the shaft s keyway when the sprocket is at the desired height on the shaft tighten down the setscrews enough to secure the sprocket on the shaft repeat this procedure for any sprocket in the drive and steering systems 3 Place the chain on the sprocket Make sure the chain is fully engaged by or wrapped around the sprocket Attached both loose ends of the chain to the master link by clamping down on the master link s clip with a pair of pliers 69 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 20
54. hange COM LAN Fort COM is selected Update Controller Software manually put in each time if correct visual readings are desired The chosen encoders have a value of 300 PPR The motor commands can be controlled using the bottom bars Make sure that as the command is moved in the positive direction the encoder reading increases positively and vice versa as you move toward the negative direction More info on the encoders can be found in the Roboteq manual To actually run the motors using this software go to the Run screen as shown in Figure 18 and click on Run in orders to start the motor motion Command 1 will start the speed motor and command 2 will control the steering motor Different data could be displayed as specified by checking the desired boxes v Data logging is possible using this software however no attempt was made since data Figure 18 PC Utility Run RoboteQ Controller Configuration Utility V1 7 02 01 05 Controller Info COM1 Active Controller not found Controller ID Software Rev Hardware Code No Data Encoder ID No Data No Data No FET Info No Amp Info No Encoder Info Eoessesesesoseceod Controls Power Settings R C Ana Specific Close Loop Encoder RC Out Codes Run Log _ Clear Log Motor 1 Iv jo Amps Empty Run pty Save Log 5 Ch Peak 0 00 00 Res Timer v oO Pewar m Command
55. he Hephaestus vehicle platform and sensory and control systems have been designed to both comply with the IGVC rules and to produce an advanced autonomous vehicle As described in the 2005 IGVC Rules the vehicles must e Vehicles must be fully autonomous during each heat of the competition The team may physically mechanically or electrically control the vehicle to the starting line however once the signal to begin the heat begins no member of the team may control the vehicle in any manner other than to stop the vehicle and end the heat e The vehicle must make direct contact with the ground as its means of propulsion Any part of the vehicle that makes contact with the ground is defined as the vehicle s mechanical footing Examples include o Wheels o Tracks o Pods e The vehicle will be expected to negotiate around an outdoor obstacle course Figure 2 shows a possible example of a course segment Obstacles include 6 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 o Full size orange and white construction barrels o Tall orange construction cones o Construction A Frame barricades o Five gallon white pails o Two inch deep by two foot diameter potholes These may be driven through with a considerable point deduction for each occurrence o Boundaries consisting of two three inch lines painted on the grass and spaced ten feet apart These may be either white or yellow
56. he LADAR system used is the SICK LMS 200 The laser scans horizontally through a 180 degree range at 0 5 resolution for a distance up to about 80m Refer to the LADAR manual in Appendix A 3 for more information The measurement information is transmitted via serial communication to the navigation computer The LMS200Setup m file sets up the LADAR which can be found in Appendix C 3 For this application the LADAR is configured so that the farthest distance is approximately 8 m Using this laser scanner the width of obstacles and their distance away from the front of the vehicle are determined 49 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 3 3 3 Navigation Strategy Autonomous Challenge The purpose of the navigation algorithm is to merge the preliminary direction angle provided by the image processing algorithm with the obstacle avoidance information obtained from the LADAR system to generate a final direction for the vehicle The algorithm is implemented in Simulink using fuzzy inference techniques as shown in Figure 46 Refer to Appendix C 4 for the Navigation controller software Note that the Navigation is almost identical to that of the Warrior Team since the same person worked on it Membership function Image Angle Fuzzy Inference of possible directions Processing System Output FIS en Final Steering
57. he electronics located on the upper platform Figure 39 is a schematic for all the component power routing 42 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Camera Draws power Lap Top from PC Computers 100 mA Data oO a E imip Duration T 2 way switch J ail 12DC 42DC Figure 39 Controller Power Distribution 3 2 5 1 Lower Platform The current draw in the lower platform is more significant with the two 24V motors drawing a combined 46A during normal operation and a stall current of 120A The Roboteq power scheme used to route this power to the motors is displayed in Figure 40 courtesy of www roboteg com To provide the needed voltage and power two 12V 55Amp hour lead acid batteries are connected in series and are fused and stowed 5 Swich on inside the battery tray attached to the bottom of the lower platform A conservative estimate of the lower platform s battery life is approximately 1 2 hours as shown in Table 6 2 x 12V Batteries 24V Figure 40 Roboteg Power Distribution 43 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Lower Platform Mechanical A V W Drive Motor Dustin 2 30 46 731 04 Steering Motor AME 55s a4 32 Controller Encoders 1 directly from controller Encoders 2 directly from a a ae controller 0 03 5 0 15 75 Table 6 Lower Platform P
58. he pause stop button in Matlab or E stop the vehicle 4 1 3 Remote Control The following are instructions to start and operate the vehicle in R C mode Fore more information on configuration for this type of operating mode please refer to section 3 2 1 3 3 1 Connect all connection to the power box located on the upper platform 2 Connect the 55A fuse located on the end of the battery tray 3 Slide the battery tray in the vehicle located on the lower platform 4 Connect the control computer to the electrical box via RS232 serial cable 5 Turn on the electrical box 6 Turn on the R C 64 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 10 11 12 13 14 15 16 17 Launch Roborun software Verify that the setting is set for RC rather than RS232 and that the E stop is active Disconnect the RS232 cable from the electrical box Hold program as you turn the controller on until the seven segment display on the back begins to blink about 5 10 seconds You are now in programming mode Pressing the set button will change the configuration on the program while pressing program will save the configuration of that program and advance to the next program Press program until a J appears on the seven segment display This stats for programming mode At this point J appears and then a 0 appears sequentially Press the set button Now you have entered programming mode for R C
59. hen the motors seemed to be running too fast and increased it when going too slow However at the 21 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 final testing after many testing trials were analyzed it was determined that the best suitable acceleration according to the specified gains discussed later 1s 2048 Many problems seemed to arise from the encoders which will be discussed This diagnostic software as shown in Figure 17 made it easy to be able to test the the encoder readings as motors spin Note that the Configuration Parameters Digital Level Threshold J 2 iy Time Base m PPR Enc 1 fie 200 Max RPH 1459 Enc 2 he 20g Max RPH 1459 Distance Divider Parameters must be stored in controller to take effect Figure 17 PC Utility Encoders Controls Power Settings A C Ana Specific Close Loop Encoder RC Out Codes Run Encoder 1 Status Measured Rel Speed lo Dist fo APM Equivalent fo Switch 1 ij Switch 2 fj Ch Counter Yalue jo Encoder 2 Status Measured Rel Speed lo Dist io APM Equivalent lo Switch 3 Ij Switch4 fj Clr Counter Value lo Motors Command PPR Pulses per Revolution of the encoders need to be m Ts Mol Stop 0 un oF Mot2 Stop 0 Reset to defaults Load from Controller Save to Controller Load Profile from Disk Save Profile to Disk C
60. hicle In order to resolve this difficulty two holes were drilled into the handle of the battery tray When the battery tray was properly in place these two holes lined up with matching holes on the outer frame of the vehicle This allowed for two bolts to be slid into place and wing nuts could be tightened in order to ensure that they did not move 3 1 2 4 Motors The motors were selected based on function gearing self locking etc and performance horsepower stall torque and RPM Sufficient power ensures that the vehicle is capable of moving at a speed of 5 mph up the maximum incline of 15 Stall torque calculations take into account the motor s ability to propel the vehicle from a stationary position up the incline Motor RPM is used in conjunction with gearing and wheel size to ensure that the vehicle can achieve the intended speed of 5 mph Refer to the 2004 Hephaestus report P21 27 in Appendix E 1 for more information on the selection process The spec sheets can be found in Appendix B 3 1 2 4 1 Drive Motor Using the vehicle parameters and requirements the drive motor selected was the Dustin 2 a modified DeWalt drill motor with the following specifications 24V 50 4 1 Gear Ratio 450 RPM 0 98 HP and 62 14 Nm Stall Torque The drive motor proved to provide enough power to climb over obstacles However a few problems were encountered with the motor The biggest problem was with the gears inside the 18 Copyright 2005 Un
61. ility The vehicle must be designed with a low center of gravity and a wide wheelbase in order to avoid becoming unstable under any circumstances that may be encountered throughout the course A possible ramp represents the only portion of the track where the vehicle is not traversing flat ground There also exists the possibility of the vehicle partially missing the ramp or falling from the ramp in which case stability is crucial to ensure there is minimal damage to the vehicle 5 Reaction Time The vehicle must be able to process sensory inputs and make appropriate adjustments in speed and direction rapidly enough so as to ensure safe navigation through the course at an appropriate speed 9 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 6 Dimensions The vehicle must have dimensions that allow maneuverability up ramps through sandpits and around all obstacles 7 Battery Life There must be enough battery capacity to enable the vehicle to complete the entire course Batteries must be accessible enough to be changed within the five minute window between heats 8 Speed The competition vehicle must be able to travel fast enough to complete the course within the maximum allotted time The winner of the competition is the vehicle that completes the course the fastest Therefore it is desired to go at the maximum speed of 5 mph while still maintaining reliable
62. in was not a practical solution It was perhaps tightened too much While the vehicle was operating on the field the steering motor was partially destroyed The chains took up too much torque and the steering motor s soul drifted out in smoke A second issue which would also assist with the previously stated problem is the large amount of mass on the upper rotating platform The high masses that are accumulated on the top lead to a greater moment of inertia This in turn causes higher efforts of the motor and greater stresses placed on the chain and sprockets This can be resolved by moving several things to a lower level The control laptops as well as the other control boxes that are placed on top could be moved to another stationary platform between the current lower platform and the upper rotating platform This would leave the LADAR mount and the payload on the top to rotate The payload could be moved back to counter the weight of the LADAR hanging off of the front of the vehicle 70 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 A third issue is the camera mount The last second modification was hideous but functional This could have easily been remedied by adding a 45 joint on the top of the mast that would allow the top to lean forward and the camera to face down over the front of the vehicle A solution to this could have easily been implemented this year had it been known b
63. ion the captured image is processed in a Matlabe environment The algorithm broken down into separate tasks 1s outlined in Figure 44 Line an istics ine ine and Heuristics Set eae Potholes Based Preliminary x Figure 44 Flowchart of Image Processing Algorithm First the image is acquired from the Fire I camera with YUV color space Then the color space is transformed to RGB space After that adaptive threshold techniques are applied to all three planes and are accompanied by region based color segmentation The image in Figure 45b shows the changes made to the image in Figure 45a during the initial color filtering The binary image in Figure 45b coupled with a Hough transform based technique detects the existence of the painted lines in the image field The white pothole is considered a distinct region in the binary image and is detected by an area threshold As a result a pothole flag is triggered if the area of the distinct region is bigger than the area threshold Figure 45a Course Image before IP Figure 45b Course Image after IP The purpose of heuristics is to aid in the preliminary direction setting The strategy is designed with the number of the edges detected and their pixel positions as its main decision making 48 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 factors To deal with dashed lane bound
64. iversity of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 drive motor The motor when driven produced a horrible grinding noise and vibration along with a very slow rotation It is not known whether or not the motor came that way from its manufacturer When the gearbox for the motor was disassembled it was discovered that the last set of planetary gears were not assembled properly When the gearbox was reassembled properly the output shaft spun faster and a lot more smoothly The next problem that was encountered with the drive motor was the bending of the output shaft Measures were taken to reduce the bending of the shaft as much as possible such extra support for the shaft Next the motor shaft started to rise up The first attempt to solve this problem was the use of a collar and roller bearings This did not completely solve the problem and the shaft still bent To solve this a longer shaft was used so that the upper supports for the platform kept the shaft from moving up and put a bearing at the top of the shaft to keep it from bending This solved our motor problems 3 1 2 4 2 Steering Motor The steering motor was selected based on its ability to turn the wheels After initial measurements of the necessary torque a 2 Hp AME 24V right angle motor with a built in 50 1 worm gear reducer was chosen The self locking feature of the steering motor s worm gear allows for a mechanical means to maintain wheel direction
65. l give a breakdown of eao O o ate IP Laptop ee the weight according to the major big parts of Qo ER o o the vehicle Note that the motors were specked LADAR_LMS 200 LS lol Camera according to a 250 lb vehicle and therefore Miscellaneous electrical components s some of the problems that occurred were due to Roboteq controller Upper Batteries 2 EE i heavy load Lower Batteries 2 as Battery Tray Wheels 6 plus drive train Le Payload 20 Total Weight 354 1 3 2 Electrical Sub Systems 3 2 1 Roboteqa DC Motor Controller The Roboteg AX2850 motor controller was chosen to control Hephaestus s steering and drive motors The microcomputer based X2850 is highly configurable It 1s capable of accepting speed and position commands via pulse width signals from a standard Radio Control receiver analog voltage commands or RS 232 commands from a dedicated computer For more information or help refer to the Roboteq manual in Appendix A 1 3 2 1 1 Selection Process The 2004 team s first option was to use a Motorola HS12 microcontroller to control the robots movement The problem with using a dedicated microcontroller to control the chosen motors is that power electronics are still needed to amplify the signal to power the motors Motion controllers which create their own PWM and have onboard power electronic amplification specific to DC motors were investigated After investigating many such cont
66. lectrical box will be discussed in greater detail later but here is the electrical box interface which is shown in Figure 13 It allows the user to alter Roboteq configuration by directly connecting to the electrical box CTRL O DB9 connection o Through this same connection the control computer drives both motors All the useable Roboteq controller pins are routed through the central shaft to the electrical box via Ethernet cable and plugged into the in CTRL I Ethernet slot The camera router and manual E Stop are connected to the electrical box in via the Ethernet cable labeled CAMERA ROUTER E STOP The LADAR is connected to the electrical box through the Ethernet slot labeled LADAR The controller computer is connected to the Parallel port labeled LIGHTS I to control the obstacle detection lights The DB15 port labeled LIGHTS O connects directly the obstacle light Figure 13 LADAR Mount 3 1 4 Mast The mast is located in the center of the platform It rises high above the platform so it can get the best possible view The mast or shaft of the vehicle not only connects the two platforms together but serves as a communication pole a camera tower wireless router tower and as an E Stop LED mount so that it is noticeable for the audience It was later modified with the addition 22 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 of a cross member which extends its vi
67. load on top Because this payload may also contain a camera for the judges its view should be unobstructed The vehicle must be operational under conditions of light rain 1 3 Performance Specification Analysis of vehicles from past IGVC competitions led the team to develop a series of specifications which would ensure that our vehicle had an appropriate design By identifying the key features of successful vehicles we were able create unique solutions to the many difficulties of the competition 8 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 1 Sensory The sensory system of the vehicle is essential for lane and obstacle detection As the sensory system s ability to detect lanes and obstacles increases the need for vehicle agility decreases This relationship exists as a result of being forced to move the vehicle more quickly if objects are not detected until they are right next to or in front of the vehicle Conversely if obstacles are detected a considerable distance away from the vehicle it would be able to react in a slower manner while still avoiding the obstacle 2 Traction The vehicle must be able to traverse a variety of terrains grass sand ramp dirt wet or dry 3 Turning The vehicle needs to accurately negotiate the path that is determined by the navigation system Agility becomes important when sensory systems are less accurate 4 Stab
68. mplifier Please refer to the data sheets in Appendix D for more information on these components The circuit for the audio amplifier is shown in Figure 26 0 speaker gt o aidhm 0 0 o Figure 26 Audio Amplifier 34 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 The output from the audio amplifier goes into the input of the bandpass filter which is the next stage of the audio e stop circuit The band pass filter design that was used was the Delyiannis Friend band pass filter circuit The bandpass filter only allows for the frequency of the sound source used to come through The other frequencies are not allowed to get through In order to make the design better in the circuit it is better to 1 kHz from Fc to get the upper and lower frequencies The sound source being used contained a center frequency of 3 kHz The calculations used to design the bandpass filter are as follows Fc 3 0 kHz Fy 3 0 kHz 1kHz 3 1 kHz F 3 0 kHz 1 kHz 3 0 1kHz 2 9 kHz Bandwidth B Fy Fy 3 1 kHz 2 9 kHz 2 kHz kHz Fc 3 0kHz uality Factor __ 2 J Q B 2kHz 15 The resistor values were then calculated using C 4 7 nF R3 S 338 8kQ 330kQ equation 2 a Fe C 3 14 3 0kKHz 4 7nF R3 330kQ 2Ho 2 1 165kQ x 160kQ equation 3 R3 330kQ 330kQ 40 2Ho 4 15 2 900 2 36702 equation 4 Figure 27 Bandpass Filter
69. n drove the chain which drove the rest of the shafts The ratio from the motor to the drive shaft was 1 1 and the ratio between the drive shaft and the other shafts is 2 1 This reduces the speed to make sure the vehicle will stay within the speed limits required by IGVC officials and also provide more torque to help move the vehicle 3 1 2 2 Wheels It is important to note that the configuration of the wheels chosen by last year s team was strongly influenced by the ramp A plane is defined by three points therefore a three wheeled vehicle will always travel on a plane even as it begins to climb a ramp It will always have three points of contact which keeps it stable at all times The three wheeled configuration is illustrated in Figure 7 On the contrary if a four wheeled diamond configuration vehicle were to begin climbing a ramp with only one wheel facing forward it would force the vehicle to tip to either its left or right wheel in order to reestablish a three points of contact meaning the vehicle will no longer be stable Figure 7 Wheel Configuration In addition to making sure the vehicle is stable by calculating the center of gravity maximum acceleration and turning rates Last year s team added three extra wheels to increase stability even more as depicted by the wheel configuration in Figure 7 where each wheel pod consists of a pair of wheels one is driven the other is free wheeling As can be seen in Figure 8
70. nstant input value However when connected to the Navigation as the input it did not work and therefore switches were used instead If there is no angle O value the vehicle will just drive straight at a high speed if the angle is positive slow the vehicle and turn right If the angle is negative take absolute value of angle since Matlab cannot handle hex to dec negative conversions slow the vehicle and turn left The following is the three m files used gt Rs232Read_Speed m gt Rs232Read_Speed_Pos m gt Rs232Read_Speed_Neg m Figure 52 Steering Speed Control Simulink Block a ee my Function Switch Relational Operator Constant Speed Only Fen Display Function Relational Speed Pos_ Steer Fon Display Constant Operator no bags Function o E Relational Abs Speed Neg Steer Font Display Constant Operator2 54 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 The actual input from navigation represents an angle in degrees However the Roboteq controller only understands pulse values ranging from 0 127 The following equation helps us achieve the actual value Degrees 300 pulses 360 degrees pulses equation 5 As for the speed we are only dealing with 2 different speeds a high speed and a low speed Remember that the maximum speed allowed for the IGVC competition is 5 mph The speed can be converted using equations function x Rs232
71. o different ways Only choose one At first a block was added to the Simulink file as shown in Figure 59 where a cumulative sum block Hephaestus 2005 Figure 59 Angle Counter 3 ee Nav Output keeps track of the angle inputted from Navigation and a Matlab function file will rewind the cord by turning the vehicle once it s limits have been reached Itis not for sure but it is believed that this is not valid because the summation box might keep reading the input from navigation before it gets a chance to refresh Figure 60 Steering Encoder Counter Mav Output Relstional Constant Operator Relational Constant Operator Relational Operator Constants MATLAB Function Sting Ecoder Counter Sig Encoder Value proper actions were taken Switch Switch 1 ay Switch 61 With that in mind another block was created which calls an m function directly as shown in Figure 60 This Matlab file will be reading the steering encoder counter instead and making judgments on that Once the encoder counter reaches its specified limits the vehicle stops and rotates and then the encoder counter is reset The only problem with this is to make sure that the encoder is not reset anywhere else in the program It is believed that at the IGVC competition the encoder was reset each time so that Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephae
72. ortional Gain Kp 0 25 Integral Gain Ki 1 12 Differential gain Kd 7 5 Acceleration 2048 29 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Figure 20 PC Utility Closed Loop Save all settin gs to the controller Controls Power Settings R C Ana Specific Chose Loop Encoder RC Out Codes Run upper platform to the controller a Max Save Profile to Disk and exit from the Roboteq Utility Reset to defauts Now to run the Robot using the Proportional Gain a Load from Controller comneh O adtonomously megaican Te Per Min Max a a a Diferental Gein TA l TE _Change COM LAN Pon Change COM LAN Port Open Matlab and the main COM1 is selected Simulink file in Appendix C 1 Update Controller Software Run the RS232 initialization Ext commands in Figure 21 and then run the program Figure 21 RS232 Setup ie up serial interface These commands initialize and open globa communication to the RS232 connected to the R serial com1 Specify comport used set R DataBits 7 set R Parity even set R Terminator CR comport must be inputted Note that the PC set R Timeout 1 Set read Timeout in 1 sec fopen R OOM utility and Matlab cannot share comports Only R Used to display settings controller It is important that the correct one application can use the active comport If fclose R
73. ower Estimation 3 2 5 2 Upper Power Distribution With the laptop computers using their internal power sources the upper platform batteries need only to supply power to the LADAR camera and RF receiver Two 12V 5 amp hour batteries are used to provide the estimated maximum power draw of 2 3A and the 24V needed for the LADAR The upper platform has over 2 hours of run time battery life as shown in Table 7 Electrical A V W Table 7 Upper Platform Power Estimation 3 2 5 3 Battery Life As seen in Table 6 and Table 7 the total worst case power consumption of Hephaestus is 1357W most of which is due to the drive and steering motors The motors themselves consume 1103W The rest of the electrical subsystems 2 computers LADAR camera emergency stop encoders consume a total of 254W Two 12 volt 55 amp hour lead acid battery packs are used for the lower platform mainly the drive and steering motors to provide a minimum of 71 minutes of run time In the upper platform two 12V 5A hr lead acid batteries are used to power all the electrical subsystems except for the two laptop computers which will be powered by their own 44 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 independent battery sources The minimum run time in the upper platform is expected to be 136 minutes 3 2 6 Computers The Hephaestus control system relies on two laptop computers to insure optim
74. placement 1 Slide LADAR onto mounting frame 2 Locate and tighten down the side clips that connect the LADAR to the mounting frame 4 2 3 Reloading Code A number of saved electronic copies of the code is critical to have One important thing to know is that all the files must be in the same directory and that the MATLAB directory should be specified to that specific folder Much effort is needed to enable a better and easier way to initialize the RS232 setup program 4 2 4 Replacement of Parts Some parts are replaced more often than others or maybe just taken off and put back on more frequently than some of the other components This section will illustrate a detailed description on how to replace parts 4 2 4 1 Encoder Replacement As mentioned earlier in the report the encoder connection terminals are very delicate The Ethernet terminal connected to the controller has the following connections shown in Table 8 Note that the wire colors are a bit different from what is mentioned in the Roboteq manual Table 8 Ethernet Pin Connections Cable Color Iwhen using standard network cable 5 University of Detroit Mercy Hephaestus 2005 The encoders that are being used for the Hephaestus has 5 input lines as shown in Figure 64 however channel Z is not used Encoder 1 is for the speed and encoder 2 is for the steering Note that this is the bottom view of the encoder Table 9 amp 10 illustrates the connections going to the
75. provides power for the RC receiver e It provides power for the LADAR e It provides power for the Camera 38 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 e It provides power and connection for the E Stop o Includes manual and wireless e Provides power for the Wireless router e Interfaces the obstacle light indicators through both a parallel port and a DB15 port Figure 34 below shows a diagram layout of the interior components of the electrical box Figure 34 Power Box F e Domenik i Mair swhoh comedian Pull down reri for RE LEO whicdir is poneret by ooral a DRS imer for LED obscie indisi mi used was replaced by sdo bas z ALK chip i rei uptd AUK chipek sik nasede o o o 1 2 Amp Ras for bosh orhe Cameras Hoki tod LED for Ro omade a Rki Logie chip weed io re reld or sop Rieky b dhe ees aid erie stor ndimi Rss logie chip for LED obrac indicstors mot used ene replaced by addon clrouk 5 65 mer chip kr LED aktam idkar mi ured peqibeced by adha dhuh lt o o o e n ZAmp tuss wrek E Stp Both ce o a Aa a SO r OR E E E E E A E E a a T E E S e a E aa I 7 ZAmp tuse tor LADAR 47V regui and hesi sik o c ooo a Cabado sol fesi fou uted K eguis Esi Wo RRE LED ikiak 0 oo 3t LED indicator connection for all components on power box AEE E ET A T E A E SO R EED indicator connection foraill components on pawar bo c oc oc oc o o a ine ee Eston reor
76. ries for a while it is recommended that the fuse be removed in case the terminals get accidentally shorted 5 To charge the batteries the fuse must be connected 6 Place the battery tray on the ground to charge it Use the Schumacher 24V charger Since these batteries are in series and are now 24 volts rather than 12 this charger must be used 7 To replace in the vehicle follow the same procedure in reverse order CAUTION The battery tray is heavy It is recommended that two people perform this 4 2 1 2 Upper Batteries Upper platform batteries are much smaller and much easier to replace or charge Remove the top off the electrical box and remove the two 12V S5AHr batteries These batteries are also connected in series and produce a total of 24V SAHrs There are two ways to charge these batteries 1 Once can connect each battery to a 12V charger and charge each individually 2 The other method would be similar to the lower platform batteries Connect the two batteries in series and use the 24V Schumacher charger 4 2 2 LADAR Swap As mentioned the LADAR had to be shared between the two vehicles as it is such an expensive piece of equipment and therefore it needed to be able to be swapped between teams 66 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Removal 1 Locate and loosen side clips that connect the LADAR to the mounting frame 2 Lift LADAR off mounting frame Re
77. rollers one seemed 25 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 ideal for our project the Roboteq AX2850 Although it was more expensive than some other controllers it has functionality that allows for complete autonomous operation Please refer to the 2004 Hephaestus report P30 31 in Appendix E 1 for more information on this section 3 2 1 2 Roboteq Capabilities The following outline is condensed for the AX2580 user s manual in Appendix A 1 e Fully Digital Microcontroller based Design e Multiple Command Modes e Multiple Advanced Motor Control Modes e Automatic Joystick Command Corrections e Special Function Inputs Outputs e Optical Encoder Inputs e Internal Sensors e Low Power Consumption e High Efficiency Motor Power Outputs e Advanced Safety Features e Data Logging Capabilities e Sturdy and Compact Mechanical Design Some of the special features that apply to this design include serial port inputs independent motor operation steering and speed closed loop feedback control Gin conjunction with optical encoders emergency stop capabilities and operation information via RS232 commands 3 2 1 3 Hephaestus Roboteq Configurations The AX2850 can be configured to control the motors by means of an analog joystick RC joystick or standard serial commands It also comes with a PC based run utility that aids diagnostics and testing Hephaestus is used in RC mode when being
78. s 2005 Once the manual e stop box is opened it can be seen that the switch has four leads There are two leads at the top and two leads at the bottom The top leads are for a normally closed configuration The Lower leads are for a normally open switch configuration which is the configuration that is used in the vehicle The wires from the Ethernet data cable that were used for e stop were blue and green stripped Connecting those wires to the bottom leads of the push button switch allowed for e stop data to be sent to the power box A picture of this device is shown in Figure 23 amp 24 below sity Of Deteoit cy Hephacstie Figure 23 Manual E Stop Internal Figure 24 Manual E Stop External 3 2 3 2 Wireless E Stop As for the wireless E stop the team went with a standard Bosch Key fob transmitter and receiver which powers up with a 12 volt source The wireless e stop operates at a frequency of 433 MHZ and has a range of 150 feet When the lock button on the key fob is pressed 12 volts is supplied to the receiver which in turn activates the e stop To reset the e stop the lock button is pressed a second time and the controller must be reset The controller already has a built in pull up resistor configuration so one did not have to be constructed for the emergency stop to work properly The proper pin connections for the receiver that were used on the Hephaestus vehicle are in Table 4 below Pin Connection Wire Color A
79. s for the R C They are Logarithmic Strong Logarithmic Week Linear Exponential Week and Exponential Strong Figure 22 shows a graph of all the control curves The linear command curve is a proportional control the control curve chosen for Hephaestus This proved to be a desired speed increase and decease for the remote control If the remote control was too sensitive that a slight movement of the toggle stick would cause rapid speed increases then the exponential strong command would be used Forward Motor Output 100 Logarithmic Strong Logarithmic Weak Linear default Exponential Weak Exponential Strong Yo Command Input Deadband Figure 22 Control Curves from Robotegq AX2580 User Manual 31 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 The R C must be conFigured to the Roboteg controller before it is able to operate in that mode There are two ways to conFigure the R D to the Roboteg controller manually with the push buttons on the controller or using the Roborun software Details on configuring the controller are provided in the Roboteq manual as well the Hephaestus quick start guide located in Appendix A 3 2 2 Steering amp Drive Encoders The 2004 team chose two optical encoders with quadrature outputs to measure speed and position Their selection process was based on amperage and pulses per revolution The Roboteq actually recommends the 200 PPR however the
80. ssage to the controller via the fprintf command if R BytesA vailable gt 0 xx fread R R BytesAvailable end Now that the speed has been setup execute the steering commands B specifies the steering motor in the positive direction fprintf R Q1 resets the steering encoder This was added at the competition in order for the steering to work appropriately and it might interfere with the encoder counter code which will be discussed at a later section Equation 5 was broken down in order to put the angle in terms of values from 0 127 The rest of the code is a repetition but this time to get the steering command out to the controller 3 3 6 Diagnostic software Figure 54 Diagnostic Simulink Blocks The Roboteq controller commands VAT LAB Function Encoder Reading make it very easy to be able to read data The Roboteq manual refers to many commands that can be sent for oe Um query purposes Three main data that Curent Reading we are interested in knowing while the mi runcioen software is running are the battery Battery Voltage Displays voltage readings encoder readings and 56 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 current readings The m files that correspond to the Simulink file shown in Figure 54 are as follows gt Rs232Read_ Current m gt Rs232Read_ Current m gt Rs232Read_Voltage m This is possible by sending a question command
81. ssing computer is an HP zx5180us This has a 2 4 GHz Intel processor and IGB of RAM This laptop also has integrated LAN and WLAN hardware however does not include any RS232 ports To function as the IP computer these are not needed however the Quatech QSP100 PCMCIA Serial Adapter does work with this laptop to provide serial ports The HP laptop was donated to the Hephaestus Team by Best Buy of Novi MI For this reason all Best Buy logos on the laptop must remain This laptop also operates Windows XP Professional From earlier testing an installation of Linux does remain The Linux distribution is Red Hat Enterprise v9 Red Hat is available through a prompt during the boot process While Linux is preferred for its stability and processor priorities it may not be appropriate for this purpose There is some evidence available which indicates Matlab is better optimized under Windows thus negating those advantages 3 2 6 2 Navigation amp Control Computer The Control computer is an IBM ThinkPad A30 with a 2 GHz Intel processor This system has 768 MB of RAM This laptop includes integrated LAN and WLAN hardware Onboard is one single RS232 port which is insufficient alone for the vehicle communications A Quatech QSP100 PCMCIA Serial Port Adaptor provides an additional 4 RS232 ports through the IBM s PCMCIA interface The IBM laptop was passed down to Hephaestus from Dr Paulik During the 2005 IGVC Competition this laptop suffered a fa
82. stus 2005 3 3 9 Navigation GPS It was intended for the Hephaestus to compete in the navigation challenge in the 2005 IGVC The electronic hardware that was slated for use for this purpose on the Hephaestus are shown in Figure 61 Figure 61 From Left to right Accelerometer compass and GPS unit A Race tech AC 22 accelerometer for measuring linear movement acceleration applied to the vehicles inertial frame A PNI micromag xx compass used to pinpoint the vehicles location and a Rikaline GPS6010 Global Position System unit to provide waypoint locations on the navigation course The integration of the sensors mentioned above make up the inertial navigation system Together they can tell the system the location of the vehicle measure the change of position distance and provide direction The network of the system is susceptible to small errors from all sensors which can add up to make the system unreliable To compensate for the errors a Kalman filter is added Kalman filter uses estimates from previous time steps to predict the current state position and velocity and used _ measurements of current state to refine prediction of new states A diagram illustrating the use of the Kalman filter oe apet PELER Error Kalman within the navigational system is depicted in Figure MEI e a 62 Figure 62 A depiction of the Navigational system 62 Copyright 2005 University of Detroit Mercy Hephaestus
83. tal error and required to be restored to factory defaults The factory default operating system is Windows XP Professional All work that was done to optimize processes on it were subsequently lost Because of this problem it is advisable for hard drive images to be made and stored externally when major changes are made to the computers Optimization steps include manually setting process priorities eliminating unused programs and closing unneeded processes Much information about Windows XP optimization can be found on the internet 46 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 3 3 Sensory System amp software The Hephaestus sensory system hardware consists of a notebook that interfaces with the navigation sensors via a serial adapter The serial adapter is a PCMCIA card that provides multiple serial ports to enable the notebook to interface with multiple sensors including the LADAR and motor controller Hephaestus vision algorithm runs on its own dedicated laptop connected to a fire wire camera The sensory system on the vehicle is completely housed on the electrical platform The sensory and vision systems configuration is depicted in Figure 42 All software was completed using a combination of MATLABe and Simulink operating under an optimized Windowse operating system Ethernet Interface PCMCIA Roboteq Controller TL Control Laptop IP Laptop Fire wire Camera Figure
84. tion was combined with the obstacle avoidance information as shown in Figure 48 The two data sets are fused together using the minimum function to produce an overall fuzzy membership function of possible steering directions This data is then defuzzified using the COLA method The COLA method finds the largest area of the output membership function and calculates its center With this method the center corresponds to the best solution for that system The defuzzified angle is acrisp angle of travel that is the final angle of travel used by the vehicle Figure 50 Light switch circuit 3 3 4 Obstacle Detection Obstacle detection is primarily handled by the St LADAR range finder The location of the bt LADAR mount enables it to pickup a variety of m anes F obstacle height IR 182 qr NASB SOCP A ono ce L NESSBN Z r C v GNOD FE The Hephaestus is equipped with lights to indicate F c1 WCC C14 when and where an obstacle has been detected PR E 19 outa ind OUTS IMS The lights are placed on the front and sides of the s oU IN2 OUTI IM vehicle and a light is also mounted on the back of the vehicle to mimic the front lights for spectators 52 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 behind the vehicle The light indicator is setup with a simple switch circuit using two mosfet switches and a 555 timer The timer circuit is
85. to be housed below the lower platform in order to help lower the center of gravity of the vehicle and must be able to be quickly removed and changed It also must be in contact with two electrical leads that would allow them to provide power to the vehicle The dimensions of the battery tray itself although being large enough to contain the two batteries is small enough to keep the tray from interfering with the motion of the wheel pods and to ensure that it remains clear of any protrusions from the ground that would hinder or possibly stop the vehicle Figure 10 Battery Tray 17 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 For quick removal and exchange drawer sliders were initially used to slide the tray under the vehicle into contact with the electrical leads However there was some question regarding the strength and durability of such a system so a new one was implemented Nylon channels were cut and bolted into the frame of the vehicle to provide tracks for on which the battery tray can slide unto These were reinforced by steel in order to ensure the strength of the system After this system was perfected it greatly reduced the time required to change battery trays and made use of the tray and lead system already in place A locking mechanism was also required to ensure that the tray would not accidentally slide out of contact with the electrical leads or fall off of the ve
86. troit Mercy Hephaestus 2005 circuit which will make the vehicle stop The reference voltage can be varied using a potentiometer A voltage divider circuit will have to be set up in order to input the required voltage into the circuit which in the case of this specific design was 10 3 V which is shown in Figure 30 Figure 30 Comparator Circuit Figure 25 Relay Circuit The relay latches the circuit which in turn stops the vehicle when the sound source has been presented The relay that was used in this design was the Omron G6H Low Signal Latching relay The relay is shown in Figure 31 3 2 3 3 1 Problems There were problems presented in this design as there will be within any design The key is to troubleshoot the problem and come up with a solution that will help to rectify the situation One problem was that there was a loading effect and negative output from the integrator circuit This was fixed by designing an inverter circuit shown in Figure 32 Figure 32 Inverter Circuit for loading and negative output With one solution solved by making an inverter circuit another problem was presented which was a loading effect due to 1K input impedance on the actual inverter circuit This particular problem was solved by using a unity gain buffer at the input of the inverter circuit shown in Figure 33 37 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 Figur
87. tup allows for high speed transfer of data between the two onboard computers Both laptops are equipped with wireless communication capabilities and linked by a linksys 802 11g wireless router allowing for remote monitoring of the vehicle s status using an external computer The wireless router is mounted on top of the pay load space by Velcro tape and enclosed in a plastic box to shield it from the 23 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 elements The antenna is mounted on the cross bar of the mast so that a better signal is received The network setup is described in details later on in this report 3 1 4 4 E stop LED Mount The vehicle is equipped with manual and wireless emergency stop options A pushbutton plunger is located to the rear of the vehicle on the upper platform When pressed the plunger connects the emergency stop pin of the motor controller to ground cutting power to the motors and halting the vehicle The same result is achieved by activating the wireless emergency stop via a Bosch automotive Remote Keyless Entry transmitter receiver unit Pressing the transmitter causes a relay to connect the same pin to ground Both the wireless and manual E stop are connected to an LED display on top of the power box When the E stop is enabled the red LED is on and off when the E stop 1s disabled 3 1 5 Stability One of the most important design criteria is to make the
88. und Vehicle Competition rules and a strict application of these performance specifications will ensure not only successful completion of the first phase of the design but also in turn will lead to the fulfillment of the goals of this project in its entirety 11 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 2 0 Design Planning Team Organization 2 1 2003 2004 Team Development The development of Hephaestus started during the 2003 2004 academic year by a team of mechanical and electrical engineering seniors Detailed study of the rules published competitors reports and previous results were analyzed to determine the design attributes of the winning vehicle This team started the research and designed and built the mechanical systems including the frame and drive train Unfortunately not much time was left to startup with the electrical systems or to test or improve upon the Mechanical parts The 2004 Hephaestus report is available in Appendix E 1 2 2 2004 2005 Team Development The 2005 Hephaestus team is interdisciplinary and composed of senior Electrical amp Mechanical Engineering students as well as graduate Electrical Engineers The team has an elected leader and is advised by three faculty members The organization chart is displayed in Figure 4 below Dr Mohan Krishnan Dr Sandra Yost Dr Nassif Rayess EE Advisor EE Advisor ME Advisor
89. ve and steering mechanisms to allow for optimal omni directional operation While Hephaestus was able to perform limited autonomous activity at IGVC this may no longer be the case when the 2006 team begins initial work However the level of work completed in 2005 should ensure that the following team is able to successful prepare the Hephaestus vehicle for the 2006 Intelligent Ground Vehicle Competition Figure 1 The Hephaestus 1 0 Introduction 1 1 Problem Statement This year marks the second phase of work on the Hephaestus autonomous vehicle platform shown in Figure 1 With the chassis designed and built in the first phase the goal of this phase is to improve the reliability of the drivetrain and complete the electrical 5 Copyright 2005 University of Detroit Mercy Hephaestus University of Detroit Mercy Hephaestus 2005 systems In short the goal for the second phase is to fully complete the vehicle in preparation for entry into the 13 Annual Intelligent Ground Vehicle Competition The Hephaestus team consists of 12 engineering students including 2 Masters students The six EE students are responsible for all of the electrical systems of the vehicle One of the EE Masters students leads the Image Processing effort and the other Navigation The four ME students have the responsibility of ensuring that the drivetrain functions properly and that all components are mounted securely 1 2 Project Requirements IGVC Rules T

2005 Hephaestus Final Report - University of Detroit Mercy ECE

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