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Educational Robot Design - USQ ePrints

1. 65 Figure 32 Assembly er eerte mc poe cate pvo ape eere ever pn 66 Figure 33 Robot 66 Robot 67 Figure 35 Children s Robot Action 2 68 Glossary of Terms ADC Analogue to Digital Converter AH Amp Hour cm centimetres Comm Port Computer Communication Port CPU Central Processing Unit D C Direct Current DLL Dynamic Link Library EEPROM Electronically Erasable Programmable Read Only Memory FLASH Rewriteable computer memory that holds its content independent of Power supply Hz Hertz 2 Master slave option for connection of multiple microchips or intelligent peripherals IC Integrated Circuit ICSP n Circuit Serial Programming Input Output IR Infrared IrDa Infrared Data Association LCD Liquid Crystal Display LDR Light Dependant Resistor LED Light Emitting Diode LVISP Low Voltage In System Programmer LVP Low Voltage Programming ms milliseconds or 0 001s NPN Opamp Operational Amplifier OCX OLE Control Extension OOP Object Orientated Programming O S Operating System PCBoard Printed Circuit Board PNP PWM Pulse Width Modulation RAM Random Access Memory S second SPI Serial Peripheral Interface UART Universal Asynchronous Receiver Transmitt
2. Figure 28 Musical note frequency and Timer settings compiled from Physics of Music Notes 2006 Pic Timer 0 Calculator 2006 In the children survey the children responded that they would like music in a robot Unfortunately the children were more thinking playing Mp3 s or CD s on the robot The final solution is a far cry from a surround sound system and it is unlikely that the classics will be converted into this format It does show that music can be simply produced using this system and very simple electronics 5 4 10 Remote Control The Remote control code replies on input from relevant keys on the keyboard via the computer software and wireless interface as discussed in section 5 2 6 The code initially checks for a valid key ASCII code so static and radio noise is ignored The relevant section is then selected to service the key press 55 The forward and reverse code checks a Boolean to decide if the robot is moving is the same direction as last time the forward or reverse code was called If it is the speed is incremented by 5 If not the speed is reset to a low speed that will stop the robot The subsequent presses will speed up the robot in the new direction Once the Robot reaches top speed further presses are ignored This system allows the robot to be sped up incrementally and the robot will then maintain its speed until it is reversed or stopped if the presses stop Left and right are controlled by inc
3. 28 RD5 PSP5 27 RDA PSPA 28 24 RCS SDO 23 RC4 SDI SDA 22 21 RD2 PSP2 55 12 13 OSC2 CLKO 14 RGO T1OSO T1CKI 15 RCA1 TA1OSI CCP2 16 RO2 CCP1 17 ROS SCK SCL 18 RDO PSPO C 19 RD1 PSP1 20 PIC16F8744 877A Figure 11 PicI6F87XA Pin out Diagram Microchip 2006b f Figure 12 Picture of Mainboard 4 2 Line and light following Circuitry Light Dependant Resistors LDR Data Sheet available on CD are used to detect the line or light differences required to follow these sources Red 5mm LED s were used in conjunction with the LDRs to reduce the effects of incidental light on the sensing The use of LEDs should also reduce the effect of a darker room where the LDRs will move towards infinite Resistance and move outside the parameters of the Microcontroller ADC Even though the LDRs were purchased at the same time from the same outlet there was significant differences in the output resistance at the same light To counteract this the 10K resistor suggested for the theoretical circuit were adjusted as necessary to bring resistances within a reasonably close range In this configuration the LDR s output is sufficient to interface with the ADC of the PIC16f877A without further electronics The addition of a terminal strips and Jumper shunt allows the Leeds
4. uite nip Rte 23 2 4 1 1 Standard transistors H Bridge 23 2 4 1 2 Mosfet Transistor H Bridge sssssssesseeeeee nennen 23 2 4 1 3 H bridge Dedicated 2 012222421 1000000 00000000000000000 23 2 5 Microcontroller 2 24 2 5 LBICTOID28 A dete Aas aan 24 25 2 PIC TOES TUA 25 2 0 SEISCH Otis tet era na utet ir RR once tutu oa acne aes 26 2 7 Wireless Transmitting and Receiving 0 enne 26 2 7 1 Infra Red Communication 1 20422 20001 000000000088 26 2 7 2 434 Hz Wireless 27 Chapter 3 Chassis Material Selection and 29 3 1 Chassis Type 002 22 2 0000000000000000000000000000000000 2 29 3 2 Chassis Material 2191204020 6000000010 000000000000 29 32 eT USE 29 o 30 3 2 9 Metal cas obe cetero e ver ree 30 3 274 Polypropyletie eee tete ti eee etit Renten pen 31 3 25 Binal t v Per
5. Dir movf DirTab w Increment the Table Index call DirSTORE subwf MemVar w are they the same btfsc STATUS Z goto WhereNow DirTab f Get the Index into the Table goto Dir Where Now Calculates the distance between the Two Bearings WhereNow movf DirTab w movwfDirD store the value are the same subwf DirP w STATUS Z goto Straight its the same direction STATUS C goto NoCarry it after goto WorkCarry 115 before WorkCarry Works the distance between the required and the actual bearing taking into consideration it the Required is before the actual if it is more then 4 the robot turns Left if it is less then 4 the rtobot turns right WorkCarry which way to go movf DirP w subtract the 2 subwf DirD w 18 the difference more then 4 sublw 0x04 btfsc STATUS C goto goright go right goto goleft yes go left NoCarry Works the distance between the required and the actual bearing this timethe Required is after the actual if it is more then 4 the robot turns Left if it is less then 4 the rtobot turns right which way to go movf DirD w subtract the 2 102 subwf DirP w is the difference more then 4 sublw 0x04 STATUS C goto goright no go right goto goleft yes go left GoLeft Turns the servo and waits while it turns Reverses a wheel to position the robot checks that the bearing for correct postion goleft call AddPerimeter bsf Direction movlw
6. R9 188R 6 Sui R13 4 8142 R12 Empi ik Sik S 1k RIS 1k 0 1 Porta Connector Setup 4 c Port B Connector Setup Mss Ys En En In 4 Dut 4 In3 Out 3 In 2 Out 2 Dut 1 Gnd Gnd 212 19 Motor 2 14 13 12 11 Q O D Whe o Final Project Port Schematics Rene M Bishop 1771272006 Page 2 of 3 Portc PortD Connector 71 Computer PicPGM cable for initial programming Ri ou T re out T2 in Peogrammng Port TRA34A Final Project Computer Wireless Interface sere __ re 1771272006 teres Appendix E Plans for Robot NON SCALED REPRODUCTIONS OF SCALE DRAWINGS FULL SCALE DRAWINGS ON CD 72 _________ 77 1272006 SSUED FOR CONSTRUCTION SCALE 1 1 1 AS DRAWN 1 OPPOSITE HAND NUMBER FINAL PROJECT BISHOP TECHNOLOGIES 4 1183 PROTOTYPE 41 102 DETAILS SHEET 1 OF 6 ALL DIMENSIONS IN MILLIMETERS U N 0 REV DRAWN CHECKED CLIENT APP D DESCRIPTION D O APP D DATE 1 D THORPE M BISHOP PROJECT No 04 3217 BISHOP_TECHNOLOGIES 73 7 72 26 2 REQ D SCALE 1 1 1 AS DRAWN 1 OPPOSITE HAND ITEM SCALE 1 1 PROJECT No 04 3217 DRAWING NUMBER
7. servo right movwf ADPos call OneSecond Wait until it turns call ReverseMotor Reverse the motor call CompassTurn Wait till we get there goto Straight Goright Turns the servo and waits while it turns Reverses a wheel to position the robot checks that the bearing for correct postion goright call AddPerimeter bcf Direction movlw servo left movwf ADPos call Wait until it turns call ReverseMotor Reverse the motor call CompassTurn Wait till we get there Straight Turns the servo and waits while it turns Starts to move the tangental distance Straight movlw servo straight movwf ADPos call Call StartMotors call Drive call AddPerimeter goto CompassMain DirSTORE The lookup table for the Compass Directions 2 103 thanks to Myke Predko and Programming and customising PicMicro Microcntrollers for this gem of a code to stop the table from going scrub movwf Temp movlw HIGH TheDir movwfPCLATH movf Temp w addlw LOW STATUS C incf PCLATH f movwfPCL TheDir dt 6 1001 NorthWest dt b 1000 North dt b 1100 NorthEast dt b 0100 East dt b 0110 SouthEast dt b 0010 South dt b 0011 SouthWest dt b 0001 West GetCompass Loads the compass inputs Turn off Readings that arent opf interest GetCompass CompassTimer banksel PORTA movf PORTA W movwf Compass bcf Compass 0x00 turn off response from
8. so we dont need else below goto Str8Grid so set the robot to straight btfsc Direction 0 choose which direction to turn call TurnLeft btfss Direction 0 make sure doesnt go straight call TurnRight back the other way Str8Grid Turns the servo and waits while it turns Starts to move the tangental distance Str8Grid movlw servo straight movwf ADPos clrf DistLeft sremove evidence of the turn call stop while wheel straightens clf DistRight call StartMotors go forward call Drive call AddPerimeter goto GridGo get next coordinate FindAngle Decides if the Bot should turn Left or right Depending on whether the angle is larger or smaller then 90 degrees 90 Degree is actually 180degrees 2 2 FindAngle movlw 0x5A 90 degrees subwf MemVar w see if is bigger or smaller then 90 btfsc STATUS C goto SetLeft goto SetRight SetLeft Sets the Direction boolean so the bot nknows which way to turn 2 2 SetLeft movwf MemVar subtract from 90 then retore value sublw 0x5A 106 MemVar bsf Direction 0 tell the bot which way to rotate goto Dirfinish SetRight Sets the Direction Boolean so the bot turns right 2 2 bcf Direction O tell the bot which way to rotate DirFinish Converts the angle back to the full 360 Degrere 50 it can be stepped out with the HallEffect sensors 2 2 Dirfinish rlf MemVar convert back to 360 degree re
9. the computer Loads each active port into the ComboBox Sets the port number then opens the next form Dim NoPort 4 As Integer Dim IsntGood As Boolean Dim A As Integer Dim b As Integer Dim c As Integer Private Sub Click set the port nuber then open the next window Open App Path amp PortNumber txt For Output As 2 Print 2 CmbPORT Text Close 2 If ResetMe True Then FrmMain Show ResetMe False End If Unload Me Set FrmPORT Nothing End Sub Private Sub Form Load through each port and see which are available On Error GoTo Erra For A 1 To 4 MSComm1 CommPort A MSComm1 PortOpen True If MSComm1 PortOpen True Then shut the Port if it did Open MSComml PortOpen False End If Next For 1 4 see which ones ended up as not available For c 1 Tob If NoPort c A Then check each Port number against the known unavailables IsntGood True not Available End If Next If IsntGood True Then IsntGood False reset for the next pass Else CmbPORT AddItem Available so add to the ist End If Next CmbPORT Text CmbPORT List 0 show the first 95 Exit Sub Erra b b 1 add the unavailable port to the list NoPort b A Resume Next End Sub 96 Appendix EEPROM Code The following codes must be inserted from EEPROM Address 00H for the Shape code to work The commas are of course spacers and not entered 0 8 2D 8 5A 8 87 8 Z 0
10. The chassis layout and structure now required some constraints and rationalisation The power supply was finalised and would be salvaged from the cheap spotlights available for 10 to 20 These carry a Sealed Lead Acid Battery SLAB charging circuit and power supply to run the charging Purchased separately these would be a substantial cost to the project The SLAB batteries are 6V and have a 4 5AH capacity which is more then enough for the little bit of current drawn by the electronics and the motors The battery would then be the heaviest part of the project The best place to carry this would be over the rear drive wheels to let the steering work easily and to stop tipping These batteries have a footprint of around 70 mm x 50mm The upright would need to be allowed for A servo for steering would also be required Allowing for the above parts and a little extra 220mm long was chosen as the working length for the chassis The drive train was the next consideration Gearing motors shafts and wheels were required The Tamiya Avante 2001 Snap together racer kit from Dick Smith electronics at 9 95 was chosen to supply one motor the drive shafts cogs and wheels required for the drive This kit is a 4 wheel drive so it has 2 drive shafts that supply all the necessary parts for the dual motors of the robot Laying the two motors and the two drive shafts and wheels out set the width at 150mm The final design of the chassis board
11. da viae re 39 Figure 14 Comp ss Board Tao eitt C DOR aaa eS 39 Figure 15 Hall Effect Processing Board sn eere deas Heap Stu sat 40 Figure 16 Hitachi 44780 LCD Pin out Hitachi 2006 41 Figure 17 Computer interface setting request dialog box 43 Figure 18 Robot Number 44 Figure 19 Main Menu entere ste 44 Figure 20 Set Axis Option 45 Figure 21 Grid Programming sous 45 Figure 22 Compass Dialog enne nennen 46 Figure 23 Shapes 47 Figure 24 Remote control Menu Verve ele eI e o ek res ea eb 47 Figure 25 RS232 Protocol Form Kim 2006 0 49 Figure 26 Binary Decimal Bquivalefts yo reete erbe n 49 Figure 27 Pic16F877A Register File Map Microchip 20066 52 Figure 28 Musical note frequency and Timer0 settings compiled from Physics of Music Notes 2006 Pic Timer 0 Calculator 2006 55 Fig re 29 Hand Span Results Prset Ye ade orbc t FEY P Fer 65 Figure 30 Questionnaire Participant Statistics 65 PACTS o Moye mentene n
12. dete E di Pep rh 43 5 22 Robot ete ee ene 43 5 22 Main eh tg ed ie Ho WE RUPEE 44 5 2 3 Grid Points Dialogs inea ed teet rt So 45 5 2 4 Compass Interface 1 1 200 000 00001 0000000000500000000000004 46 5 2 5 Shapes Menus isnt ee eee tee 47 5 26 Remote I DERE RERBA ERR 47 5 3 Interesting Aspects of the Computer 48 5 3 1 The Communication Port Gode cecus eite ced qt era PO EHE 48 5 3 2 The Grid C OUR a menos estin 48 5 3 3 The Compass coden enm enas 49 5 4 PICI6F877A Peta 50 S LDR Sensor 50 5 4 2 Compass Coding 2 202000600000000000000000000020000000 000 een nennen 3 50 5 4 3 Grid following 2 4 12224220000000000000000000000000000000000500000 51 544 Motor Code PR 52 5 4 5 Shapes mri 52 5 4 6 Servo 2 2 444844 10 0000000000000000000000000000 entree nennen 52 SAT Port eh E e EC EE 53 5 4 8 Interrupt 4 2 1 424040 400000000000000000000000
13. Chr x 240 64 End If If YNumber True Then Caption Caption amp Y amp y 240 Else Caption Caption amp Y amp Chr YFinal 64 End If End If End Sub Private Sub Form Load Sets printbox and line settings postions form and form items Calls the relevant code to draw the axis and dots MainAxis Cls MainAxis Line 0 0 0 0 MainAxis Refresh set axis size with 120twips between each dot If XNumber False Then MainAxis Width Xaxis 240 171 Else MainAxis Width Xaxis 1 240 171 End If If YNumber False Then MainAxis Height Y Axis 240 175 84 Else MainAxis Height Y Axis 1 240 175 End If set buttons and screen height frmAxis Height MainAxis Height 2500 frmAxis Width MainAxis Width 3000 CmdOption 0 Top MainAxis Height 600 CmdOption 0 Left MainAxis Width CmdOption 1 Top MainAxis Height 600 CmdOption 1 Left frmAxis Width 2 CmdOption 2 Top MainAxis Height 600 CmdOption 2 Left frmAxis Width 2 3 Label3 Top frmAxis Height 500 Label3 Left frmAxis Width 2 Label2 Left frmAxis Width Label2 Width 2 Label2 Top MainAxis Height 1200 PrintAxes Draw the axis DrawAxis set up the axis List DirectionList Top MainAxis Top DirectionList Left MainAxis Width MainAxis Left 500 ReDim 10 ReDim 10 DoNext True End Sub Private Sub Form Unload Cancel As Int
14. FINAL PROJECT BISHOP TECHNOLOGIES 201 4 1184 PROTOTYPE 41 102 DETAILS SHEET 2 OF 6 y ALL DIMENSIONS IN MILLIMETERS U N O LE lt a a lt a a vw n lt u a u T u gt REV1 D THORPE M BISHOP ISSUED FOR CONSTRUCTION 74 1771272006 2 REQ D 1 AS DRAWN 1 OPPOSITE HAND SSUED FOR CONSTRUCTION 22 3 5 ITEM SCALE 1 1 1 AS DRAWN 1 OPPOSITE HAND PROJECT No 04 3217 BISHOP TECHNOLOGIES FINAL PROJECT inicr BISHOP TECHNOLOGIES 201 4 1185 PROTOTYPE 41 102 DETAILS SHEET 3 6 Ah ALL DIMENSIONS IN MILLIMETERS U N O lt a a a a lt a z o n o u vy a ao u gt fe 92 EL AL a gt a 75 N N E lt v lt ES m gt o a 521 6 1 REQ D SCALE 1 5 N 7 PROJECT No 04 3217 BISHOP TECHNOLOGES FINAL PROJECT DRAWN NER BISHOP TECHNOLOGIES 201 4 1186 PROTOTYPE 41 102 revison DETAILS SHEET 4 OF 6 S HHEHHHHI ALL DIMENSIONS IN MILLIMETERS U N O a a a lt a v a a a a v a
15. If x Mod SpanSize gt SpanSize 2 Then if gt half span go to next XStart Int x SpanSize 1 SpanSize Else XStart Int x SpanSize SpanSize else drop back one End If Find the closest axis point for start of line in y If y Mod SpanSize gt SpanSize 2 Then if gt half span go to next YStart Int y SpanSize 1 SpanSize Else YStart Int y SpanSize SpanSize else drop back one End If End Sub Public Sub LineEnd x As Single y As Single snaps the line to the gridponts for the end of the line or Dragline Find the closest axis point for end of line in x If x Mod SpanSize gt SpanSize 2 Then if gt half span go to next XEnd Int x SpanSize 1 SpanSize Else XEnd Int x SpanSize SpanSize else drop back one End If Find the closest axis point for end of line in y If y Mod SpanSize gt SpanSize 2 Then if gt half span go to next YEnd Int y SpanSize 1 SpanSize Else YEnd Int y SpanSize SpanSize else drop back one End If End Sub Private Sub CmdOption Click Index As Integer process the relevant button push Select Case Index Case 0 reset drawing MainAxis Cls DrawAxis 5 0 Case 1 Program the Robot with the drawings FrmInterface Show DoMultiple Unload Me 81 Set frmAxis Nothing Case 2 exit MainAxis Cls DrawAxis S 0 FrmMain Show Unload Me Set frmAxis Nothing End Select End Sub Public Sub MainAxis MouseDown Button As Integer Shift As
16. Service5 movlw b 00010000 store Pin 4 5 and 7 so can check for changes andwf HoldPortB w movwf LastPortB4 movlw b 00100000 andwf HoldPortB w movwf LastPortB5 movlw b 10000000 andwf HoldPortB w movwf LastPortB7 BCF INTCON RBIF REset the values saved initially so the program continues where it left without error 2 IntEnd movf pclath w Restore PClath movwf PCLATH movf status w Restore status register movwf STATUS swapf w f Restore W without changing flags swapf w w retfie 120 H 8 Sound Code Excerpt 2 2 Load Next Note loads the next note in the seqence and looks for the the final note 2 2 Load Next Note movf NotePosition w call Songs get the next note for the song movwf Note movlw a L make sure its not the last note subwf Note w skpnz goto StopMusic movlw 0x40 see if it letter or Number subwf Note w STATUS C goto WorkLetter goto WorkNumber movlw 0x30 get the hex equivalent of the number subwf Note w GetNote Finds the Hz equivalent of the note 2 2 GetNote call MusicalNotes movwfNote banksel TMRO movwf TMRO load the note Hz into the Timer0 banksel NotePosition incf NotePosition movf NotePosition w call Songs get the time for the note movwfNoteTime movlw 0x30 get the hex equivalent of the number subwf NoteTime w movwfNoteTime incf NotePosition goto WorkLetter find the Hex equivalent of a letter 2 2 121 WorkLetter movlw 0x37 Sub
17. This is particularly useful when combined with the ICSP In Circuit Serial Programming In this mode the chip can be programmed in circuit via the serial port of a computer with inclusion of a small amount of electronics This removes the problem of having to programme remove then insert in its final circuit and the related issues of Static Discharge Damage and or bent pins Finally this processor has a low Power consumption rate and can be operated on 5 Volts which lends itself nicely to this sort of application All of the data above referenced from Microchip 20064 2 5 2 PIC16F877A The full MICROCHIP range are very compatible with one another over the full range They have similar features and similar Programming commands This means that the PIC16F877A has all the same features as the PICI6F628A with the following additions 4 Banks PORTS of 8 Pins for input and or output 1 Bank PORT of 3 Pins for input and or output 7 Analog Digital input port Outputs for both SPI and I2C modes An SPI Data Out pin An SPI Data In pin A Data I O pin 2 Capture In Compare Out PWM Out pins Slave select for the synchronous serial port Read control for the parallel slave port Write control for the parallel slave port Select control for the parallel slave Parallel slave port The chip also has much a much larger Flash Program Memory RAM and EEPROM Data memory The data above and the functionality included on this Microcontroller Mic
18. and not at the risk of the Council of the University of Southern Queensland its Faculty of Engineering and Surveying or the staff of the University of Southern Queensland This dissertation reports an educational exercise and has no purpose or validity beyond this exercise The sole purpose of the course pair entitled Research Project is to contribute to the overall education within the student s chosen degree program This document the associated hardware software drawings and other material set out in the associated appendices should not be used for any other purpose if they are so used it is entirely at the risk of the user Professor R Smith Dean Faculty of Engineering and Surveying iii Certification I certify that the ideas designs and experimental work results analyses and conclusions set out in this dissertation are entirely my own effort except where otherwise indicated and acknowledged I further certify that the work is original and has not been previously submitted for assessment in any other course or institution except where specifically stated Matthew D Bishop Student Number D9811486X Signature Date Acknowledgements I would like to thank my wife Hope and my 3 children Monika Sarah and Chloe for their support during my time studying Thanks must also go to my supervisor Mark Phythian and Frank Young Without your help this would never have come together Table of Content
19. u D THORPE M BISHOP fi 76 20 30 9 50 60 70 9 100mm 10 10 7 20 HOLES SCALE 1 5 DRAWING NUMBER FINAL PROJECT BISHOP TECHNOLOGIES 201 4 1187 PROTOTYPE 41 102 DETAILS SHEET 5 OF 6 BEA ALL DIMENSIONS IN MILLIMETERS U N D 77 0 1 2006 SSUED FOR CHECKING lt a a n a a a u vy a a lt a uv u 5 8 1 REQ D SCALE 1 5 N 7 PROJECT No 04 3217 BISHOP TECHNOLDGIES N FINAL PROJECT E ipd EN 5 TECHNOLOGIES E 4 1188 PROTOTYPE 41 102 DETAILS SHEET 6 OF6 ALL DIMENSIONS IN MILLIMETERS U N 0 78 20 30 40 50 60 80 90 100mm 10 _______ 7712 2006 D THORPE M BISHOP ISSUED FOR CHECKING lt a e a E Q n a a lt v a u T Im gt PROJECT No 04 3217 BISHOP TECHNOLOGIES FINAL PROJECT BISHOP TECHNOLOGIES 201 4 1189 PROTOTYPE 41 102 GENERAL ARRANGEMENT J ALL DIMENSIONS IN MILLIMETERS U N O 79 AL Appendix F Visual Basic Code Excerpts F 1 Grid Coding FrmAxis Code Description ok K K ok ok ok The
20. 1200 1A0h General General General Purpose Purpose cave Register Register Register Register 80 Byles 80 Bytes 80 Bytes 96 Bytes EFh 16Fh accesses ron accesses 70h plas TOh 7Fh TOh 7Fh 70h 7Fh FFh 17Fh Bank 0 Bank 1 Bank 2 Bank 3 E Unimplemented data memory locations read as 0 Nota physical register Note 1 These registers are not implemented on the PIC18F876A 2 These registers are reserved maintain these registers clear 2003 Microchip Technology Inc DS39582B page 17 Figure 27 Pic16F877A Register File Map Microchip 2006b 5 4 4 Motor Codes The motor codes Appendix H 4 control the built in PWM function They use the built in Timer2 function to control CCP1 and CCP2 pins of PORTC Figure 10 This section also controls PIN 3 of PORTC This has been set to enable the H Bridge circuitry Forward and reverse is also controlled from here by raising the logic level on the required pins 5 4 5 Shapes Codes The preset shapes are preloaded into the Microchip EEPROM APPENDIX G This memory stays viable when the power is removed from the microcontroller and is therefore in memory at all times The shapes movement code uses most of the Grid following code to operate Code is shown in Appendix H 5 5 4 6 Servo Interfacing The Servo interfacing section Appendix H 6 acts in conjunction with the TMRO inbuilt timing function TMRO is set to run a continual 20ms PW
21. 56 While this is 70 dearer then the target 150 price it has to be remembered that all components were purchased at retail prices over the counter Purchasing at trade or wholesale price as would be available to a manufacturer would easily bring the price down to the targe price of 150 Interestingly the cheapest parts and simplest methods of manufacture were searched out at all times 6 2 Achievement of Objectives The aims and objectives set out in the Project Specification at the beginning of the project were a b c d e g Design construct and commission a small robot suitable for use by primary school students of grades 6 and 7 Research the current school syllabus and teacher requirements so the project will be relevant Obtain an overview of the children s expectations of the project and other aspects to make the project suitable for a child s use Create the robot from low cost components so the final project costs less than 150 Build the robot from off the shelf components where possible so it could be supplied in kit form and be assembled by a resourceful teacher from plans Design robot structure movement components and spatial awareness components taking into consideration interchangeable parts Add functions including musical and tactile interface 58 Create a computer interface for interaction with the robot i Create relevant codes for the microchip including distance r
22. ADPos goto GetNext GoR movlw d 2 movwf ADPos goto GetNext GoStr8 movlw d l movwf ADPos goto GetNext Store the front value sreset 1 for the next round set direction set direction set direction 100 H 2 Compass Code Excerpts CompassMain call wait 2 seconds while the compass call settles and get current position movlw 0x01 each bearing equals 100mm movwf Tangent call Get required Compass Bearing movwf MemVar direction STATUS Z call wait 2 seconds while the compass call make sure have a good reading movlw OxFF check if finished subwf MemVar w skpnz goto CompassEnd call CompasssStart goto CompassMain CompassMain Checks to see it the Actual and Required Bearing ar the same CompassStart movwf MemVar Check to see if Compass Bearing xorwf Compass w and required direction are the same btfsc STATUS Z goto Straight they are the same so continue forward FindCompass Checks the Actual Bearing against a Table of coordinates FindCompass movf DirTab w Increment the Table Index call DirSTORE subwf Compass w btfsc STATUS Z goto FindDirection incf DirTab f Increment Table Index goto FindCompass FindDirection Checks the Required Bearing against the above table FindDirection movf DirTab w movwf DirP DirTab 101 Compares if the Actual and Required Bearing are the same
23. Driver Receiver Texas Instruments USA vanRoon T 741 OP amp Tutorials op amps Operational Amplifiers Retrieved December 117 2006 from http www uoguelph ca antoon gadgets 741 741 html Bibliography Underwood J amp Underwood G 1995 Computers and Learning Blackwell Publishers Oxford UK Aird 2001 The education and care of children with severe profound and multiple Learning Difficulties David Fulton Publishers London UK Boschmann E ed 1995 The Electronic Classroom A Handbook for Education in the Electronic Environment Learned Information Inc Merdford NJ Jacak W 1999 Intelligent Robotic Systems Design Planning and Control Kluwer Academic Publishers New York Shircliff David R 2006 Build A Remote Controlled Robot McGraw Hill Professional New York Williams 2003 Amphibionics Build Your Own Reptilian Robot McGraw Hill Professional Publishing New York Miles P amp Carroll T 2002 Build Your Own Combat Robot McGraw Hill Professional New York Bergren C 2003 Anatomy of a Robot McGraw Hill Professional Publishing New York Braga N C 2002 Robotics Mechatronics and Artificial Intelligence Newness Publications Burlington M A Predko M 2000 Programming and Customising PIC micro Microcontrollers McGraw Hill Publishing New York Braga N C 2005 Mechatronics for the evil Genius McGraw Hill Publishing
24. PWM or Pulse Width Modulation is the process where the power is switched on and off at a particularly high speed rate The on off rate is usually measured in microseconds so the motor is only receiving power a percentage of each second This gradually adds up to a percentage of time on in a minute so the speed is adjusted accordingly Interestingly the on and off rate is at such a speed that measurement with a multimeter would show a constant voltage supplied and measurement requires an oscilloscope Figure 5 Simulated PWM Output There are a couple of ways to incorporate a H Bridge into the design 22 2 4 1 H Bridge A H bridge can be constructed using Transistors and a handful of discrete componentry Figure6 Battery Positive Figure 6 Transistor H Bridge Circuit The Complete BJT Circuit 2006 There are several configurations of these depending on the style of Transistor used These have there own consideration so will be addressed separately 2 4 1 1 Standard transistors H Bridge A suitable H bridge can be easily built from standard Transistors like the PNP BC557 General Purpose Transistor Phillips 2006 Data Sheet available on CD These are quite capable of handling the power but suffer with large current drains that can be detrimental to a self contained unit operated from a battery 2 4 1 2 Mosfet Transistor H Bridge A Bridge constructed on Mosfet Transistors overcomes the issues of power because
25. Prescaler for each note but this would be a little involved so the single prescaler approximation was chosen Two Prescaler ranges were tested and are shown in Figure 27 The 1 32 scale proved to be very 54 inaccurate and cut out the bottom notes where as the 1 16 Prescaler very nicely covered the note range With music timing is important By setting Timer to fire every 1 4 second a very basic 4 4 timing was possible The choice of music was then an issue Copyright needs to be considered so older classical tunes that had sheet music readily were available on the Internet chosen The three tunes selected were Also Sprach Zarathustra by Richard Strauss Blue Danube by Johan Strauss and Ode to Joy by Ludwig van Beethoven music scores com 2006 Small sections of these were reproduced in the code table The format for each note included the note number Figure 27 column 5 and the time from the sheet music e g Low G played for 4 timing beats 15 represented by 54 The rest of the notes of the tune were laid out in similar fashion Musical Note Freq Hz Prescaler 1 32 Prescaler 1 16 Hex Assign Low C 262 139 20 1 Low D 294 152 45 2 Low E 329 163 69 3 Low F 349 169 79 4 Low 392 178 99 5 440 187 116 6 B 494 195 132 7 C 523 198 139 8 D 587 205 152 9 E 659 211 163 A F 698 213 168 B G 784 218 178 C High A 880 223 187 D High B 988 195 E High C 1047 198 E High D 1175 205
26. are relatively even In the end it came down to the fact that the sender would most likely be plugged in at the back of a computer and possibly not be able to be used in plain sight of the receiver The TX434A and the RX434 sender and receiver from Oatley Electronics www OatleyElectronics com were chosen for the application because of price and availability More information on these two components on the CD 2 8 RS232 discussion The RS232 output from a serial port is based on an old system where logic 1 is at 10 volts and the logic 0 is set at 10 volts This system has its own standard which sets the pins of the cable and Computer port good source for information on this is http www camiresearch com Data Com Basics RS232 standard htm Unfortunately the voltage for a Logic 1 is 5 volts and Logic 0 15 Zero Volts in a microcontroller The microcontroller is also unable to produce voltage at the correct voltages to interface directly with a computer The addition of a wireless connection between the computer and Robot also amplifies this problem as the wireless connection has similar limitations One way around this is to incorporate a RS232 Transmitter Receiver IC into the Transmission side of the circuit near the Computer An ideal IC for this is the Maxim RS232 Texas Instruments 2006 Data Sheet available on CD The Max232 coupled to the output of the Computer turns the voltages into a logic level acceptable by the Micro
27. call stop while wheel move movf DistRight w movwf Perimeter save the perimeter DistLeft clf DistRight reset wheel distances Lcont Counts the pulses to see if the distance has passed Lcont movf Angle w subwf DistLeft w count how many pulses the unit has travelled STATUS C isover the required goto StopMotor goto Lcont continue until equal TurnRight This code is used by all of the movement code The servo is turned and the bot pasues while this happens the distance is rloaded and the bot counts the pulses TurnRight movlw d 2 load a right turn movwf ADPos call stop while wheel move movf DistRight w movwf Perimeter save the perimeter clrf DistLeft 109 X DistRight reset wheel distances Rcont Counts the pulses to see if the distance has passed Rcont movf Angle w subwf DistRight w count how many pulses STATUS Z 1 pulse 1 1 5 degree goto StopMotor goto Rcont continue until equal Drive count clicks let them add up every so amny and increment match robot will move 100mm for each spot on the grid of compass 100mm 33 clicks normally or 66 becasue of the boolean variable GridBool movlw 0x42 check to see 1f 66 clicks have passed subwf DistRight w Take readings from the right wheel STATUS Z goto Next100 goto Drive Next100 Increments for the next 100 Next100 incf DistForward ncrement the distnc
28. can take place The modification of the encoding wheel for incorporation into the robot was less then satisfactory 15 Another way to access this style of sensing would be to manufacture the encoding wheel The manufacture of an accurate encoder of this diameter could be done by a Cutting from a thin soft material that could be cut with a Stanley knife or a fine cutting implement b Cutting using a precision cutter e g a laser cutter from a thicker piece of material c Injecting or moulding in plastic by a plastics manufacturer The first method is not satisfactory when used in a situation where users in this case children could possibly touch or otherwise manipulate the sensor wheel as material fine enough to be cut in this way would be flimsy at best The method of manufacture is also dangerous and not conducive to producing an accurate final product The second method of manufacture is ideal for small run production like this and would create an extremely accurate product Unfortunately it is quite expensive and has to be done with an expensive precision cutter Realistically this unit will be at best a small run production Having the dies struck to make an encoder wheel by injection or moulding as in c is very expensive The savings on these methods come as large quantities are produced and the cost is shared out among a multitude of items Though this is the ideal method to produce this sort of precision item the cost
29. is not the dream language it may appear to be Grasping its concepts is difficult it is often not very well explained and it has no formatting in the way of modules or the OOP of higher languages possess To make the code more readable the code for this project have been placed in similar section e g Motor codes and codes relating to these go into the same section This made debugging the code much simpler The microcontroller controls nearly every aspect of the robot from producing the PWM for the motors and servo to counting the distances moved A good amount of commenting is done in the ASM file so an overview of the more important modules will be shown here The full coding is available in Appendix H 5 4 1 LDR Sensor Code The LDR coding Appendix H 1 involved using the ADC functionality of PORTA on the PIC16F877A This function allows the use of the internal ADC unit of the microcontroller This basically charges and discharges an internal capacitor using the resistance found on the Port Pin The capacitor discharge is timed then the PIC converts the time into a digital value Using this method the LDR with the lowest value the one with the line under it can be found by continually polling the 3 pins If the LDR to either side is on the line the robot will turn so the lesser value is in the centre 5 4 2 Compass Coding The compass pins are attached to Pins 4 5 6 and 7 of PORTA Figure 10 These pins are set to digital input becau
30. shape for the user to send to the robot 5 2 3 Grid Points Dialog The Grid Points Dialog Figure 20 allows the user to set the robot a path of movement via a grid system The Grid can have its axes set to X and Y Letter X Number Y Letter X Letter Y Number X and Y Numbers The Axis Setting Dialog allows these to be set each time Figure 19 44 Set Axes Options BAX Set Axes Options X Letter X Letter X Number X Number 9 Y Letter Y Number Letter Y Number Figure 20 Set Axis Option Dialog Y E 2 Xxx E Ro gt lt gt gt Clear Grid Program Bot Exit Remember the Robot will start at the or 0 0 The Dots represent 10 cm 100mm spacings Figure 21 Grid Programming Dialog Points are plotted on the grid at the same time the points are displayed in the column on the left so the format of X Y navigation that can be easily understood by children 45 To operate the cursor is moved around the grid A Dragline will show where the line will go Right clicking will remove the line Left clicking will place the line as a solid line and activate the next Dragline Two things that need to be remembered a The robot starts from the 0 0 point whatever combination this becomes by the settings as any
31. the Mosfet is substantially better on the current drain issue The main problem with Mosfets is the price 2 4 1 3 H bridge Dedicated IC There are quite a few H Bridge dedicated IC s available in Australia The main consideration in the selection of a H Bridge was price verses suitability for the process The majority of the H Bridge IC solutions were quite expensive and quite a bit more powerful then would be required here These where immediately removed as competitors From the rest the L293D STMicroelectronics 2006 Data Sheet available on CD from STMicroelectronics was a standout in both price 23 and features It was capable of driving the two motors that were required and the circuitry was incredibly simple to initiate into the design This unit 15 also compatible with microcontrollers Though some very interesting Transistor H Bridge designs were found the IC version of the H Bridge was the automatic choice because of the ease of implementation and the price 2 5 Microcontroller Selection There are quite a few varieties of microcontroller available The selection approach was a little slanted because of previous experience and success with the PICAXE range of microcontrollers based on the MICROCHIP range Research on the Internet and at the USQ Library also verified the popularity ease of use and prolific information sources for this range of microcontroller On the MICROCHIP website www microchip com there 15 also a
32. the rear of the Hall effect sensor was then required The South of the magnet being attached to the sensor meant the sensor would detect when the teeth of the magnetic cog are in the vicinity These assemblies and the magnets can be seen in Figure 9 The Hall effect processing board features an LM833 low noise OpAmp ON Semiconductor 2006 Data Sheet available on CD The LM833 is set up in a Window Comparator configuration using a voltage divider with 2000 potentiometer and a 1000 resistor for each side of the robot as the voltage reference comparator is a circuit that compares an input voltage with a reference voltage The output of the comparator then indicates whether the input signal is either above or below the reference voltage VanRoon T 2006 Figure 15 Hall Effect Processing Board The UGN3503 has an output voltage of around 1 volt when connect in the format when there is no metal in its presence The 2000 potentiometers are then adjusted to match this voltage so logic 0 0 volts is sent The output from the LM833 15 then a square wave moving between 0 volts and 5 volts that the Pic 16F877 can interpret as movement To complete the drive assembly and incorporate position sensing two 33 tooth metallic cogs were chosen from a hobby shop These allowed the measurement of 1 515mm increments when calculated from the 98mm wheel diameter of the previously selected wheels This was thought to be quite accurate enough for this ap
33. to be turned off if the board is used in Light following Mode Figure 12 38 A Schematic is provided in Appendix D Figure 13 LDR Circuitry 4 3 Compass Circuitry Two issues need to be acknowledged with the Dinsmore 1490 Compass module discussed in Chapter 2 3 The first being that the pins are very closes together and are a little flimsy in construction According to the specification sheet crossed or reversed current can destroy the internal circuitry Likewise time in the solder pool is also a concern To combat this a 16 pin IC socket was cut into 4 x 3 pin sockets to insert the component and help remove the above issues The result can be seen in Figure 13 Pull up resistors were then all that was needed to interface with the PIC16F877A The pull up resistors create logic 1 or 0 depending on the bearing of the compass This logic level can be read directly by the PIC16F877A Figure 14 Compass Board 39 4 4 Hall effects circuitry The Hall Effects assemblies were constructed in as 3 part design The first being 2 x 33 pin cogs attached to the drive shafts of the robot This supplied a method of accurately reading distance in a 13mm diameter piece Because of the room constraint a single UGN3503 Hall effect sensor board was created for each side of the robot This board consists of only the sensor and points for power in and sensor output The board also enabled easy mounting under the robot The addition of a magnet to
34. would be plugged into the relevant socket on the mainboard and the construction content of the project would be achieved 3 3 2 Printed Circuit Board Mounting A slotted upright was then designed to handle the PCBoards Experimentation showed that 1mm thick slot 5mm deep adequately help the boards in place while letting a child push the board assemblies into it The riser design took into consideration that the main board would lie in front of it though provision for it to be in another spot was available The upright also needed to be robust enough to handle abuse There was no real need for stress testing because of the minimal stresses and the properties of Polypropylene so a 40 mm section was decided on as it looked substantial enough to do the job The riser board Appendix E Sheet 4 Item 6 was the result This board allowed assembly without any sort of fasteners It is worth mentioning that only 2 circuit board assemblies now require fastening on this project They are the two boards holding the Hall Effect Sensors These need the stability and adjustment that a screw and slotted board offers The remaining boards are attached to the unit by locating slots Two side braces were also designed Appendix E Item 5 Sheet 3 to give added sideways stability in the event the robot was dropped on its side or it was tripped over Figure 8 shows these in place Figure 8 Riser with slots 33 3 3 3 The Chassis and Drive Assembly
35. 00000000000 53 5 49 Sound SCCHOM x52 nier nc ee 53 5 4 10 Remote Control AG tete bua phi 55 Chapter 6 Conclusions eb eee edet ceteri ds 57 GL PRA COSE ity ductis dtu 57 6 2 Achievement of Objectives ener nennen enne 58 6 3 PUT ICE orden ordine biased Gelb rur ie dte hd 59 BiblioSraphiy aea Ca UY 61 APPENDIXES deep onem voter MeL 62 Appendix A Project Specification 62 Appendix B School 63 Appendix C Low Voltage In System Programmer SCHEMATIC 69 Appendix D Electronic Schematics for 70 Appendix E Plans for 72 Appendix Visual Basic Code 80 Grid Coding 80 F 2 Compass Coding FrmCompass esses eene 90 F 3 Active Comm Port Find essere 95 Appendix EEPROM 4 sse eene eene enne nennen 97 Appendix PICI6F877A code Excerpts 98 H 1 LDR ASM Code sess enne 98 vii H2 C mp ss Code Exce
36. 30 c The weight of the project would immediately increase in the case of solid metal construction translating into cost as motors and drive assemblies would need to be increased in size to cope d If the chassis is made from steel plate it would require rust protection More expensive metals like stainless steel could be used but the costs increase accordingly Galvanized iron could also be used to make a folder chassis though cut edges could be a source of rust e Cut Hazard Improperly prepared steel plate can also harbour sharp edges or snags that can cause injury of these issues made the use of metal less then desirable for this application Metal was therefore removed from the option list 3 2 4 Polypropylene Polypropylene is a thermoplastic that has some great properties for this style of application These include Lightweightness Good Tensile strength Impact resistant High compressive strength Excellent dielectric properties Resists stress cracking Retains stiffness and flex Non toxic Easily fabricated It is also readily machined with woodworking tools which is perfect for the manufacture of this item Polypropylene Specifications 2006 The main disadvantage is that the plastic is very soft so this limits the amount of construction that could be done as an in class project Repeated assembly would soon strip the plastic from the screw holes 3 2 5 Final selection After careful consideration of the ab
37. 5 23 8 2 12 5 Insect 4 19 1 6 7 Other Person 0 0 3 18 8 Horse 0 0 1 6 25 Guinea Pig 0 0 1 6 3 Dog 1 4 8 1 6 3 Skater 0 0 1 6 3 Good 0 0 1 6 3 Looking Guy Figure 33 Robot Appearance BOYS Speed Car Race Hekker Helpful Educating kind Educational Robot RaFaCe Really Fast Car ESC Educational speed Car FERK Friendly Educational Robot Kid FER Friendly Educational Robot PERy Partisipating Engine robot ER Educational Robot FER Fun Educational Robot Lenny CuCeR Computer Controlled Robot Keniffer because it is a good Name FRED Friendly Robot Educational Device TED Talking Educational Device ACER Australian communication Educational Robot FRTH Friendly Robot that Helps ERFiK Educational Robot for Kids KLR Kids Love Robots SKIC Social Kind Intellectual Contraption KILL Kind Insect Little and Loyal 66 Kind Knowledgeable Friend GIRLS ADRIS REMI Really Exciting Machine Invention CAF Child and Adult Fun SALT Safe Active Loving Talent SQUIRT Socializing quiet understanding independent rough talkative FAST Fast active safe tiny Crotella Caring Robot organises talks excitement long amazing BABER Big and Better Electronic Robots HEDA Helps Anyone Do Anything KeFeR PIG Pretty Intelligent Girl ART Australian Robot Toy Kefer Kid Friendly Educational Robot TER Tal
38. 6 2D C2 5A 6 87 Z 16 4 44 4 87 4 Z F 8 34 4 87 8 Z 20 3 98 4 12 5 48 5 76 4 87 4 Z 2D 3 9E 4 16 4 2D 4 44 4 70 4 87 4 Z 20 4 A6 4 0 4 E 7 7 68 4 87 4 Z 2D 3 98 4 16 4 2D 4 44 70 4 87 4 7 97 Appendix H PIC16F877A code Excerpts H 1 LDR ASM Code Excerpt LDRStart call SetIMRO TMRO call Init motor Setthe PWM call SetADC call SetLED call StartInt Start Global Interrupt call StartMotors start motors LDR movf iw Get the Index into the Table incf if Increment the Table Index call ADSTORE movwf ADCONO set the LDR to look at call AD PORTA check the current LDR movf i w 18 this the front LDR sublw 0x01 btfss STATUS Z goto PutF movf iw is this the Left LDR sublw 0x02 STATUS Z goto movf iw Is this the right LDR sublw 0x03 STATUS Z call movf ADHF w subtract the high bits front from right movwf Temp subwf ADHR w STATUS Z higher bit is the same so check against left 98 goto CheckL BTFSC STATUS C one was bigger goto CheckL front was lower same check as above sright was lower movf ADHR w subtract the high bits front from right movwf Temp subwf ADHL w btfsc STATUS Z higher bit is the same so find lower goto CheckAllLower BTFSC STATUS C one was bigger goto GoL Right was lower goto GoR Left was lower find which pin is lower depending on the pin turn
39. Erase the before axis point line frmAxis MainAxis Line XStart YStart StoreX StoreY store coordinates redim array if necessary 5 85 1 If S Mod 10 0 Then s gt last 10 add another 10 to the variable ReDim Preserve XCoord S 10 ReDim Preserve Y Coord S 10 End If XCoord S XStart 240 YCoord S Y Axis YStart 240 put the coordinates in the list box to demonstrate plotting If XNumber False Then Listtext x amp Chr XCoord S 65 Else Listtext x amp XCoord S End If If YNumber False Then Listtext Listtext amp y amp Chr YCoord S 64 Else Listtext Listtext amp y amp YCoord S End If If S 1 Then XCoord S 0 Y Coord S 0 End If DirectionList AddItem Listtext add the direction to the list 83 NextPosition Xcoord S YCoord S S XEnd x YEnd MakeLine True End If frmAxis MainAxis DrawMode 6 frmAxis MainAxis DrawStyle 6 End Sub Public Sub Mainaxis MouseMove Button As Integer Shift As Integer x As Single As Single detects the mouse movements Draw the stretch or rubberband line Dim XFinal As Integer Dim YFinal As Integer If MakeLine Then frmAxis MainAxis AutoRedraw True frmAxis MainAxis Line XStart YStart XEnd YEnd XEnd x YEnd MainAxis Line XStart YStart x y XFinal Xaxis x YFinal Y Axis y 240 If XNumber True Then Caption X amp x 240 Else Caption X amp
40. FT Connector PGM Connector Connector to Printer Port LPT GND Connection Tabie for PIC Intertace PIC Connector PIC GND 5 PIC MCLR MCLR 4 PIC DATA R87 6 PIC NOTE Pin 83 RBS has to be connected to GND via a 1k resistor on the PIC Development Board Christian Stadler picpgm cable 26 06 2004 12 18 24 PIC Progr ammer Cable 11 0 5 istian Stadler Sheet 1 1 D E 69 Appendix D Electronic Schematics for Robot BCSS 208 11050 RAI ANI RE1 TIDSI Porta 2 1 Connector RC3 SCK RA4 T CKI RC4 SDI Connector E RAS AN4 RCS5 SDD 9 rann 5 3 epi RCTARM 5 PortB 39 P LOK 51 RD2 PSPB 42 RBS RD3Z PSP3 PortD i RD4 PSP4 Connector 44 RB 7 PGD RDSZPSP5 What osci CLkIN RD6 PSP6 ER 15 E OSC2 CLKOUT RD7 PSP7 E REB RD cs r1 3 22 REg CS SH VSS VSS 24 100R A Final Project Main Board P Rev 1 8 Tl Bishop 1671272006 Page 1206 23 70
41. Grid code is based on Multilin zip by Ethan www freevbcode com ShowCode asp ID 1240 Instructions One left mouse click turns the line drawing on and anchors the starting point of the line second click of the left button sets the end of the line Right clicking the mouse terminates the current Line Dim MakeLine As Boolean Dim XStart As Integer Dim YStart As Integer Dim XEnd As Integer Dim Y End As Integer Dim StoreX As Integer Dim StoreY As Integer Dim XCoord As Integer Dim Y Coord As Integer Dim ConvertHex As String Dim WhatUpto As Integer Dim DoNext As Boolean Const SpanSize 240 Dim S As Integer Const Pi 3 14159265358979 Dim Quadrant As Integer Dim Tangent As Integer Dim xHold As Integer Dim yHold As Integer Dim Done As Boolean Public Sub DrawAxis Draws the grid points on the picturebox Dim XPos As Integer Dim YPos As Integer Dim x As Integer Dim y As Integer set picture box settings MainAxis DrawMode 6 put points on axis For x 1 To Int ScaleHeight SpanSize For y 1 To Int MainAxis ScaleWidth SpanSize frmAxis MainAxis PSet XPos YPos move to the next spot XPos XPos SpanSize 80 Next XPos SpanSize YPos YPos SpanSize Next reset drawmode MainAxis DrawMode 13 End Sub Public Sub LineStart x As Single y As Single snaps the line to the gridponts for the start of the line or Dragline Finds the closest axis point for start of line in x
42. Integer x As Single y As Single detects the mouse button pushs Static StoreX As Single StoreY As Single Dim Listtext As String If S 0 Then x 0 y MainAxis Height End If If Button 2 Then right button is pushed so retract line frmAxis MainAxis Line XStart YStart XEnd YEnd MakeLine False XEnd 0 YEnd 0 Exit Sub End If Tf the MakeLine Flag is true If MakeLine True Then Erase the Stretch Line frmAxis MainAxis Line XStart YStart XEnd YEnd Turn inverted draw off frmAxis MainAxis DrawMode 13 Calculate Closest end axis Point to XStart and YStart LineEnd x y Draw the final line frmAxis MainAxis Line XStart YStart XEnd YEnd RGB 0 0 0 restore coordinates redim if necessary S S 1 If S Mod 10 0 Then ReDim Preserve XCoord S 10 ReDim Preserve Y Coord S 10 End If XCoord S 240 YCoord S Axis 240 Display Number Or letter If XNumber False Then 82 Listtext x amp Chr XCoord S 65 Else Listtext x amp XCoord S End If If YNumber False Then Listtext Listtext amp y amp Chr YCoord S 64 Else Listtext Listtext amp y amp YCoord S End If DirectionList AddItem Listtext NextPosition XCoord S YCoord S 1 S Set new start line points XStart XEnd YStart Y End Else The line has not been drawn yet StoreX x StoreY y Find the closest axis point LineStart x y
43. M cycle Another timed code sequence adds the 13 7 or 18 ms high pulse that selects the direction the servo turns 52 5 4 7 Port Interfacing This area initialises all the timer functions in TMRO and and all of the Ports on the microcontroller for their required function 5 4 8 Interrupt section The Picl6F877A has a special interrupt function which be set to react to various events These events can be anything from internal specifically timed interrupts to external inputs from the ADC or other pins on the microcontroller Once the event fires the interrupt the code leaves what it is doing and moves immediately to the code that services required event Using this interrupt feature allows the microcontroller to interface with the outside world As such the interrupts are the heart of the coding Important codes like the emergency push button stop are coded here The interrupt section also houses the Hall effect sensing response so positioning takes priority The timer functions and the music start here Most importantly the wireless interfacing 15 done here so the message 15 received on the wireless port as it is ready Code detailed in Appendix H 7 5 4 9 Sound Section There are several ways to implement sound on a Pic16F877A Many involve converting Midi files or similar into electronically identifiable data Research into implementing music showed that the Pic16f877A is capable of interacting with peripheral electro
44. New York 61 APPENDIXES Appendix A Project Specification FOR TOPIC University of Southern Queensland FACULTY OF ENGINEERING AND SURVEYING ENG4111 4112 Research Project PROJECT SPECIFICATION MATTHEW BISHOP EDUCATIONAL ROBOT DESIGN SUPERVISOR Mr Mark Phythian SPONSORSHIP Faculty of Engineering USQ PROJECT AIM Design a low cost educational robot which can be incorporated into current school curriculums targeting student of grade 6 and 7 to stimulate an interest in Engineering The bias will be to create the robot so it can be reproduced with off the shelf components where possible or supplied in kit form Another focus will be to make the robot a usable tool that can be used often to demonstrate relevant educational ideas and principles PROGRAMME Issue A 27 March 2006 1 2 Research the current school syllabus and teacher requirements so the project will be relevant Obtain an overview of the children s expectations of the project and the other aspects to make the project suitable for a child s use Research all suitable off the shelf components including chassis gearbox and controlling components taking into consideration compatibility and price Create a computer interface Design Robot structure movement components and spatial awareness components taking into consideration interchangeable parts and functions Musical functions and tactile interface Create relevant codes for the mic
45. RE 2 3 PIC18F876A 877A REGISTER FILE MAP File File File File Address Address Address Address Indirect addr ooh Indirect addr Indirect addr 100h Indirect addi TMRO oth OPTION_REG amp th TMRO 1011 OPTION 181h PCL 02h PCL 82h PCL 102h PCL 182h STATUS h STATUS 83h STATUS 103 STATUS 183h FSR 04h FSR 84h FSR 104h FSR 184h PORTA 05h 85h 105h 185h PORTB och TRISB 86h PORTB 106 TRISB 186h PORTC ozh TRISC 87h 187h PORTD oem TRISD 108h 188h PORTE coh TRISE gon 109h 189h PCLATH oAh PCLATH 8Ah PCLATH 10Ah PCLATH 18Ah INTCON INTCON eBh INTCON 1088 INTCON 188 PIR1 EEDATA 10Ch isch PIR2 Dh 2 8Dh EEADR 100 EECON2 18Dh TMRiL oh PCON 8Eh EEDATH 10Eh Reserved 18Eh TMR1H OFh 8Fh EEADRH 10Fh Reserved t amp Fh TICON toh 90h 110h 190h TMR2 Th SSPCON2 91h 191h T2CON 12h PR2 92h 12h 192h SSPBUF 13h SSPADD 93h 1143h 193h SSPCON 14h SSPSTAT 94h 14h 194h CCPRIL 15h 95 116 195h CCPRIH 16h 96h 116 196h CCPICON 17h 97h General General RCSTA 188 TXSTA 98h Register 18h Register 198h TXREG 19h SPBRG 99h 16 Bytes 119 16 Bytes 199h RCREG 1Ah 9Ah 19Ah CCPR2L 1Bh 9Bh TIBh 19Bh CCPR2H 1Ch CMCON 9Ch 11 19Ch CCP2CON 10 CVRCON 11Dh 19Dh ADRESH_ 1Eh ADRESL 9Eh 19Eh ADCONO 1Fh ADCON1 19Fh zn
46. This is then attached onto the chassis at the front Appendix E Sheet 7 and can remain in situ Figure 10 Assembled Robot with boards in situ 36 Chapter 4 Electronics Design 4 1 Test Bed Robot Main Board Once the method of programming and computer interfacing were finalised the next step was to build a testing bed Originally this was done with a dedicated board using PicPGM http www members aon at electronics pic picpgm and the Low Voltage In System Programmer circuitry LVISP Appendix C interfacing with the PIC16f877A on breadboard The programming powering down removal and reinsertion became time consuming and quite monotonous As a result the first major board designed to be the test bed was instigated The first item in the design was to implement the LVISP so the chip could be programmed and then quickly run to test the code If there was an issue the PIC needed to be able to be quickly reprogrammed again To get around this Header Terminal Strip and Jumper Shunts were incorporated in the design to facilitate the change A careful look at the PIC16F877A Pin out Diagram FIGURE 10 will show that while the microcontroller offers a good variety of functions its layout is a little jumbled This meant designing to bring relevant areas together and have all of the same PORT pins accessible from the same point Doing so allowed for a cheap user friendly header plug system to be used to stop the possibility of cab
47. University of Southern Queensland Faculty of Engineering and Surveying Educational Robot Design A dissertation submitted by Matthew Darrell Bishop In fulfilment of the requirements of Course ENG4111 and 4112 Research Project Towards the Degree of Bachelor of Mechatronics Submitted January 4 2007 Abstract By introducing children in the final years of primary school to simple Engineering principles children may consider Engineering when they make the choice of career in the early years of high school Using a Robot as this vehicle ties the already existing fascination children have with science fiction to a practical classroom interaction This interaction should effectively draw attention to Engineering and create interest in the disciplines it encompasses The exposure of children to Engineering in this intimate format should help career choice and the growth of engineering in the future University of Southern Queensland Faculty of Engineering and Surveying 4 111 Research Project Part 1 amp ENG4112 Research Project Part 2 Limitations of Use The Council of the University of Southern Queensland its Faculty of Engineering and Surveying and the staff of the University of Southem Queensland do not accept any responsibility for the truth accuracy or completeness of material contained within or associated with this dissertation Persons using all or any part of this material do so at their own risk
48. ameters for the project The following points were highlighted as useful from a teacher s point of view The robot should able to generate shapes squares rectangles etc and demonstrated areas and perimeters 12 Beable to operate on coordinate system to demonstrate graphing Have the ability to draw a picture from the coordinate system Be able to demonstrate basic compass navigation Have LCD screen for output to take the children away from the computer after the initial programming and e Possibly offer some sort of challenge It was also discovered from the interview that a child could concentrate for up to an hour so the robot tasks could be reasonably involved It would also be possible to incorporate building the robot as a lesson in itself A copy of the current teaching curriculum was shared with relevant sections highlighted It showed many areas where the robot would be useful and easily integrated into the classroom environment The child orientated section of the data collection was in the form of a statistical information collection and a questionnaire for the children The teacher who was approached had experience in the area of child questionnaires and ethics After reviewing the proposed questionnaires he considered them to fit within the requirements of ethics To maintain the ethical approach the children s questionnaires were conducted as a class activity without the author be
49. ape SetHep movlw 460 banksel EEADR movwfEEADR goto SetShape SetOct movlw d 77 banksel EEADR movwfEEADR goto SetShape 114 H 6 Servo Code Excerpt SERVO INTERFACING 2 sends the required PWM on time so Timer0 knows how long to set the high time and position the servo set PulseM go Straight movlw d 13 movwf DelayCount call SERVOON MainDelay 0018 return set PulseL go left movlw d 7 movwf DelayCount call SERVOON MainDelay 0011 return set PulseR go Right movlw d 18 movwf DelayCount call SERVOON MainDelay 0022 return SSERVOON Controls the on time for the servo positioning allows multiples of 1000 SERVOON movf DelayCount w see if Delay amount 0 btfsc STATUS Z RETURN call TheDelay decf DelayCount f Decrement delay goto SERVOON TheDelay this is the 100us Pause movlw d 11 movwf usDelay TENusDelay wait 1005 decf usDelay f movf usDelay w nop nop 115 btfss STATUS Z goto return 116 H 7 Interrupt Code Excerpt InterruptHandler movwf W save W movf STATUS w bef STATUS RPO bef STATUS movwf Status save STATUS movf PCLATH w PCLATH because the code movwf pelath is larger then 1 page PCLATH btfsc was it the wireless connection goto RX HANDLE INTCON TMROIF Was TMRO interrupt goto int service it BTFSC TMRIIF Tim
50. are Consideration 5 1 Computer Software Programming With extensive experience in the basic language a copy of Visual Basic 6 0 Professional and access to a plethora of Visual Basic programming sites for reference the obvious choice for the computer software was Visual Basic The advantages of this software are Pre Existing DLL s for functions like Port Access Graphical interface for User Interfacing Modular programming for ease of debugging 5 2 The Computer Software This section will be a user manual for the Software Extensive code remarks are incorporated into the Visual basic code that is incorporated on the CD 5 2 1 Comm Port set up Each time the software starts it searches for 2 files the Port number file and the Robot Id file If these are missing example at the first start the program asks for these to be set If the Port Id file PortNumber txt is missing the following dialog is opened Figure 16 By simple error control the program finds the available Comm Ports and adds them to a dropdown combo box The user then selects the relevant box and the port number is saved Set Port SET COMPUTER PORT FOR ROBOT INTERFACE Figure 17 Computer interface setting request dialog box 5 2 1 Robot ID Set up If the Robot ID file ID txt is missing the following Dialog is opened Figure 17 The dropdown box is populated with 26 ID Letters A single unit can use the first letter This fun
51. basic notes of A B C E F and G in its three forms lower middle and high a total of 21 notes If this was to be translated for use on the PIC16F877A some more thought was needed as to its implementation The note frequencies could be hard coded against a fixed number system so an individual note could be accessed This can easily be done by using a look up table similar to the ones being used for the compass code With this in place a song could be coded into another table and the individual note frequencies would be called as required The Hexadecimal number system is based on 16 numbers For easy implementation of the hard coded notes the earlier number of notes would need to be trimmed Considering that a musical rest should be included this left 15 notes A quick look at some prospective music showed that realistically the 15 notes could be taken from Low C to High C this is demonstrated in Figure 27 Column 1 The range would allow a reasonable amount of songs to be played if required Producing the frequencies took some more consideration A musical frequency could be looked at another way as a PWM signal A PWM signal historically sends a square wave at a particular frequency figure 5 The on and off period for PWM is a regular on off pulse that if matched to the frequencies of a musical note the problem would be solved Unfortunately the dedicated PWM pins were previously taken by the motor control circuitry of the robot Using
52. bot suitable for use by primary school students of grades 6 and 7 b Research the current school syllabus and teacher requirements so the project will be relevant c Obtain an overview of the children s expectations of the project and other aspects to make the project suitable for a child s use d Create the robot from low cost components so the final project costs less than 150 e Build the robot from off the shelf components where possible so it could be supplied in kit form and be assembled by a resourceful teacher from plans f Design robot structure movement components and spatial awareness components taking into consideration interchangeable parts g Add functions including musical and tactile interface h Create a computer interface for interaction with the robot 11 i Create relevant codes for the microchip including distance recognition motion light and line following and spatial recognition j Create relevant interfacing components to implement computer robot normal functioning and remote control If time permits Research methods to shape plastic Create a shaped plastic exterior The full specification is available in Appendix A Learning from observing is an excellent way to learn Combining the above specifications into a robot will allow the teacher to reinforce theory with application Using the icon based interface on a computer then activating the robot via the Wireless interface w
53. coder rings and more sensors to decipher the Gray code produced Miniaturisation of the electronic sensors again becomes an issue For the reasons listed above this method was rejected 2 1 3 Rotary Encoder Potentiometer Rotary encoder potentiometers are readily available at high end electronics suppliers rotary encoder works in a similar method to the encoder wheel above often in the Gray encoder configuration The main difference is that in place of light metal contacts brush on contact and non contact areas to give a binary representation of the current position These encoders range in price according to the accuracy or style of encoding starting from as little as 10 and ranging up to several hundred for the more accurate optical variety Besides the obvious problem of price for accuracy this style of device has it s own unique issues in regards to incorporation into this designed While the devices themselves can be quite small there is a problem in this instance in regards to mounting because of the closeness of surrounding mechanical and chassis parts This method was rejected because of these issues 17 2 1 4 Stepper Motor Stepper motors are available in all shapes and sizes and are readily available from old office and computer equipment The most useful aspect of these particular motors is they can move in small increments of degrees Power has to be sent to particular coils within the motor in a particular order to
54. controller and wireless system The Maxim IC also has a built in Voltage Pump so it can convert the Microcontroller output to the correct voltages to interface the microcontroller signal to the computer if required 28 Chapter 3 Chassis Material Selection and Design As the robot would be used by children in a classroom situation and would most likely be mistreated the chassis of the robot required particular consideration The following designs and materials were considered and or tested 3 1 Chassis Type Selection One Constraint on the design of the project was the ability to turn in its own axis There are 2 ways to effectively do this either using tracks like a tank or by creating a three wheeled design Motion by tracks is a common mode of locomotion in the modern world Many vehicles use this method of motion and it is extremely successful and stable Tracks would be a simple method of implementing motion in this situation as well as steering Tamiya offers a kit in their educational Construction series that would work for this situation while supplying the chassis for the robot in one piece A three wheeled robot in comparison could be made quite simply by inverting a Servo on some sort of chassis and building a mount for the wheel Because the PIC16F877A has the ability to offer PWM to a servo this method would be easy to incorporate into the design The Track method would have easily provided the chassis and a simple met
55. ction 1s not properly implemented here though the code 15 ready to apply it as multiple bots were not available for the testing 43 Set Robot ID Set Robot Number Sets the Robot ID if Multiple robots are operated Click OK if only a single robot is available TOTES Figure 18 Robot Number Dialog 5 2 2 Main Menu The main dialog allows access to the relevant areas of the robot interface Figurel8 shows the interface Main Area Lele File SetPort SetRobot ID Line Follow Light follow Grid Points Compass Points Shapes Remote Control Figure 19 Main Menu Dialog The menu options do the following a File Opens Exit that allows the user to Exit the program b SetPort opens the Set Port Dialog above and allows the port to be changed Set Robot Id opens the Robot Id Setup above and allows the Robot number to be changed The Menu buttons have the following Functions a Line Following immediately sends the robot the command for Line Following mode b Light Following immediately sends the robot the command for Light following mode 44 c Grid Points opens the Grid Dialog Figure 20 so a design can be made on the grid d Compass Points opens up the Compass Point Dialog Figure 21 so compass points can set for the robot to negotiate e Shapes opens the shapes dialog Figure 22 so the user can select a
56. e Grid Code Many aspects of this code were taken from Multilin zip by Ethan at www freevbcode com ShowCode asp ID 1240 The original code was horribly fragmented and hard to follow The code has been reworked and optimised The code Appendix F 1 initially plots an evenly spaced grid of dots on a Picturebox control From there a Dragline is fed out behind the cursor This allows a visual indication of where the line will go The code also allows for the line to drawn from the nearest Grid Point and the removal of the Drag Line when the left mouse button is pushed A coordinate history has been made available so all past coordinate additions can be erased Because of the difficulty in working trigonometry and angles in the PIC16F877A code that works out the angle and movement in relation to the last was created in Visual Basic This code breaks each direction down into an angle of 360 degrees in relation to the last direction with straight ahead being 0 The required rotation is broken down into quadrants and the new heading is placed into its quadrant and the angle amount is deducted The angle and the tangent is then worked out from the remaining angle that is less then 90 The Quadrant amount in degrees is then re added e g 250 will be in the 3 Quadrant 250 180 is 70 degrees The 70 angle and the tangent are found by the tangent rule The 180 will be then be re added to give the true angle It was discovered that the g
57. e egt 31 Bs Chassis DeSIPR oet eret ente ipe eA TO Eco a 32 3 3 Wh tis Assembly isset EE e re docte tede eed eda 32 3 3 2 Printed Circuit Board 001001 eere eene 33 3 3 3 The Chassis and Drive 2 34 3 34 Dnvedarountilg ssec ire ERE 34 3 3 5 Stee nin ge xev oie ete a etti eei 35 3 3 6 Peripheral Mountings 2 22 22 01 00000100000006000000000000000000000000 36 Chapter 4 Electronics a e 37 vi 4 1 Test Bed Robot Main 2 0 00400 0 8 eene 37 4 2 Line and light following Circuitry sess 38 4 3 Compass oet eee URN IH E toes 39 4 4 Hall etre ipee eret heme eerte eret ie eri iei 40 4 5 H Bridge Circultry aou Iced 41 4 6 434 Hz Transmitter and Receiver 4004 41 4T E SD c 41 4 8 Stop Button 42 4 9 Connecting Dee eere ieee 42 Chapter 5 Software nennen 43 5 1 Computer Software Programming 43 5 2 The Computer aine ane he tener hee Geos 43 5 2 Port idee
58. e forward movf Tangent w subwf DistForward w see 1f we have gone far enough yet STATUS Z goto StopMotor goto Drive 110 H 5 Shape Code Excerpt Shape code Calls the relevant shape memory area in EEPROM and loads the Shape rotations and distances one at a time prints the perimeter and sings at the end 2 the shape number 2 OutPut none 2 ShapeStart call SetHall call SetTMRO TMRO call SetTimerl call Init motor Set the call StartInt Start Global Interrupt return find which shape is to be stepped out Get the poistion in the table 2 2 2 BeginShape movlw 0x01 subwf Received w btfsc STATUS Z goto SetSQ Get the Square movlw 0x02 sublw Received btfsc STATUS Z goto Get the Rectangle movlw 0x03 sublw Received btfsc STATUS Z goto SetPen Get the Pentagon movlw 0x04 sublw Received btfsc STATUS Z goto SetHex Get the Hexagon movlw 0x05 sublw Received STATUS Z goto SetHep get the Heptagon movlw 0x06 111 2 2 sublw Received STATUS Z goto SetOct Get the Octagon movlw 0x07 sublw Received STATUS Z goto SetEQ get the Eq Triangle movlw 0x08 sublw Received STATUS Z goto SetSC get scalene triangle SetShape Load the angle to turn and the distance of a side Move the robot into positon then step out the distance SetShape call EEPROMRead movwf MemVar movlw OxFF sublw MemVar STATUS Z goto Sha
59. e money to purchase many of the learning aids that children use in school Parents want their children to have an education that includes learning with technology based influences to prepare them for the future They know they that this helps create steppingstones for future education choices for the changing world that will be our children s By providing the above system while keeping that the system costs down the real outcome of this project will be a system that can be used in modern schools Using the data collected from the questionnaire the project direction was chosen 14 Chapter 2 Component Selection An important aspect of the project involved finding cheap and effective ways to implement the mechanical requirements of the Robot This section will discuss this aspect of the project Earlier on in the project consideration was given to the size of the final product and ideally for several reasons focus would be put into keeping it small This consideration was kept foremost in mind along with price when considering below 2 1 Position Sensor Selection Position sensing offered its own unique challenges It had to be kept in mind that non technical people could possibly assemble the Robot if a kit was developed Special consideration was therefore required to find the easiest method to enact the position sensing whilst keeping in mind the skill requirement involved The following systems were considered 2 1 1 Slotted Encoding
60. e robot to do e g Follow a line on the floor walk forwards and backwards play music when it finishes its tasks 64 c Questionnaire Results Average Hand Size for children Grade 6 and 7 Boys Girls 103 90 90 80 80 94 84 81 77 88 98 118 100 108 90 100 92 95 105 83 105 90 110 96 90 86 100 80 105 90 108 95 107 95 110 100 109 104 2162 1474 Average 98 27 92 13 Mode 90 90 Minimum Value 77 80 First Quartile 90 5 85 25 Median Quartile 100 90 Third Quartile 105 95 25 Maximum Value 110 118 Figure 29 Hand Span Results Boy Girl Other Total 21 15 37 Figure 30 Questionnaire Participant Statistics Boy Girl Walk 6 28 5 9 56 Roll 9 42 9 4 25 Slide 2 9 5 1 6 3 Other 4 19 1 67 Others On a sphere Hover Flies Fly like an insect Figure 31 Movement 65 Time Boys Girls 5 mins 0 0 0 0 10 mins 0 0 1 6 7 20 mins 7 33 3 18 8 30 mins 8 38 4 25 Other 15 mins 0 0 1 6 3 1 hr 1 4 8 4 25 Ihr 30 mins 1 1 8 0 0 2 hours 2 9 5 1 6 3 3 hours 0 0 1 6 3 1 week 0 0 1 6 3 6 days 1 4 8 0 0 As long as 1 4 8 0 0 Figure 32 Assembly Time Boy Girl SciFi Robot 11 57 5 31 3 Car
61. easons plywood was rejected as a chassis material 3 2 2 Maranti pine This wood is very readily available at any hardware shop or timber sales Itis very strong and is quite reasonably priced Its main downfalls are a It is timber and as such can have raw edges or splinters This can be a danger for children or people handling the robot There also could be a danger of injury from splinters if the robot brushed past someone while moving across the floor b Pieces of Pine 150 mm wide as required for this project are prone to cupping which would make the robot inoperable overtime unless the timber is treated Treating could be achieved by painting another process and another cost for the project Pine was therefore removed as an option 3 2 3 Metal One of the strongest chassis materials available would be metal It is very readily available and could be formed as a flat plate or folded sheet While this would be the strongest option it offers its own unique disadvantages a Metal is a highly conductive material This means that all electric and electronics would need to be specifically insulated This of course would increased the time and cost involved in building b Special tools and skills are required to machine or fold solid and sheet metal Machining of metal is also labour intensive and costly It also requires specialty tools to do successfully so construction would need to outsource this part of construction
62. ecognition motion light and line following and spatial recognition j Create relevant interfacing components to implement computer robot normal functioning and remote control of the main objectives were touched on and completed during this project Some of the ways covered may not be optimum e g the music coding but all area were attempted and a result was achieved The final cost was a little disappointing Achieving these objectives was much more time consuming than expected One main area was difficulty debugging the microcontroller live The expensive boards with microchip debugging would have made for some much less frustrating times In hindsight PICBasic would have been used because PIC Assembler is a huge learning curve even for someone who has a background in assembler Though it 15 second nature now a considerable amount of time was spent working with poor documentation and even worst examples Another difficulty was self funding the components This cost more then expected especially trailing different ideas during the process and sometimes resulted in delays in sourcing components Something like this would be much better done in house at the university 6 3 Further Work There is possibility for future work with this project This could be a valuable tool for use in schools and could easily be implemented and distributed on scale To integrate in schools the following area would need to be addressed a A plastic m
63. ect Case Quadrant 88 2 greater the 90 degree and less the 180 TheAngle 90 90 TheAngle Case 3 greater then 180 and less then 270 TheAngle 180 TheAngle 4 greater then 270 and less then 360 TheAngle 270 90 TheAngle Case 5 deal with 90 degrees TheAngle 90 Case 6 TheAngle 270 End Select divide the angle in half because there isnt a full amount of degrees available in the grid this way 360 degrees can be represented in binary 255 TheAngle CInt TheAngle 2 XCoord W Tangent YCoord W TheAngle HoldMe TheAngle amp amp Tangent Listl AddItem HoldMe Xcoord W Listl AddItem Y Coord W xHold store the x value for comparison yHold y store the x value for comparison End Sub Private Sub TimerSend slow the send down a touch Theoretically this should be able to be done at full board but in practice it seems the work better with a pause timer1 value 71000 1 second reality timer is only accurate to 1 18 of a second Done True End Sub 89 F 2 Compass Coding FrmCompass Dim x As Integer Dim y As Integer Dim XLast As Integer Dim YLast As Integer Dim XBack As Integer Dim YBack As Integer Dim XX As Integer Dim CoOrd As String Dim XMax As Integer Dim Done As Boolean Const MoveMe 240 Private Sub CmdCompass Click Index As Integer Sends to the screen the directions to the list box displays the line on the sc
64. eger clear everything from memory and exit FrmMain Show Unload Me Set frmAxis Nothing End Sub Private Sub PrintAxes sets the picturebox dimensions sets and positions the axis numbers or letters Dim i As Integer Dim c As Integer Dim As Integer Dim D As Integer set the pictureboxes to suit the axes PicYAxis Height MainAxis Height 350 PicYAxis Top MainAxis Top 300 PicY Axis Left MainAxis Left PicY Axis Width DirectionList Left MainAxis Width 1000 DirectionList Height MainAxis Height frmAxis Width DirectionList Left DirectionList Width 500 240 If XNumber False Then 85 D 1 Else D 0 End If c 0 A PicY Axis CurrentX For i YAxis To 1 Step 1 240 Set Position and Display the Yaxis numbers PicY Axis CurrentY c Axis CurrentX A If YNumber True Then PicY Axis Print i Else PicY Axis Print Chr i 64 End If Next i PicY Axis Print doxAxis End Sub Private Sub DoMultiple sends the list of controls to the BOT Dim A As Integer add the robot number to the code and send set baud rate bit length etc MSComm1 Settings 2400 N 8 1 set port number MSComml CommPort PORTNUMBER SEND THE X DATA TO THE BOT 5 5 1 YCoord S 255 For A 2 ToS ignore the start position TimerSend Interval 10 10 m s TimerSend Enabled True Do wait for tht timer DoEvents dont lock up th computer Loop Until Done True Done False reset the valu
65. er us micro seconds also can be designated us 0 000001 s UHF Ultra High Frequency VREF Voltage Reference ZIF Zero Insert Force Chapter 1 Project Introduction 1 1 Introduction As a child takes the rite of passage to adulthood there is an expectation in our society that the child will make a life choice in the form of a career at the same time There are a plethora of choices for child these days and it is very difficult to expose a child to a variety of career possibilities especially the more technical Engineering is a field that is in everyone s daily life but is often overlooked as a career choice Providing a device that can bring engineering to the attention of children whilst entertaining and educating will give children a taste for what engineering has to offer in their future This introduction could leave a lasting impression that could help a future career choice when it is required This project is focused on bringing a robot design that can be readily used in the Queensland teaching curriculum The current curriculum is a results based plan that allows the teacher a great deal of flexibility to incorporate tools such as this in a custom made teaching programme By introducing relevant areas of the curriculum into its design this project will be able to be adopted as a pertinent teaching tool 1 2 Research Objectives The main objectives of the project are a Design construct and commission a small ro
66. er1 GOTO Tmrl INT YES Service the Timer Overflow Interrupt goto PORTBInt will be the PORTB interrupt then goto IntEnd handles the input from the wireless connection either sets a mode or loads the next values to RX HANDLE movf RCREG w movwf Received movlw reset subwf Received w btfsc STATUS Z goto ResetAll btfsc GridBool 0 shas one of these modes been set goto GridHandle so service it btfsc CompassBool 0 goto CompassHandle btfsc RemoteBool 0 goto RemoteHandle btfsc ShapeBool 0 has one of these modes been set goto BeginShape so service it movlw 0x01 Line Follow n light follow subwf Received w btfsc STATUS Z bsf LDRBool 0 movlw 0x02 Grid subwf Received w btfsc STATUS Z 117 goto GridSet movlw 0x03 subwf Received w STATUS Z goto CompassSet bsf CompassBool 0 movlw 0x04 subwf Received w STATUS Z goto RemoteHandle movlw 0x05 subwf Received w STATUS Z goto ShapeSet Compass Remote Shape something else just reset the port RX END bcf RCSTA CREN reset everything for the next message bsf RCSTA CREN bcf goto IntEnd processes the Timer 0 interrupt decides what mode the timer is in and processes TMRO int bef INTCON TMROIF movlw 0x01 subwf MusicBool w skpnz goto DoMusic movlw d 106 movwf TMRO bsf 0 movf ADPos w sublw 0x01 btfsc STATUS Z call PulseM movf ADPos w sublw 0
67. es TimerSend Enabled False If MSComm1 PortOpen False Then open the port MSComml PortOpen True End If send the details ConvertHex Hex Y Coord A MSComml Output ConvertHex send angle If A S Then 86 once the end bit FF is sent do no more ConvertHex Hex XCoord A MSComm1 Output ConvertHex send distance End If If MSComm1 PortOpen True Then close the port MSComm1 PortOpen False End If Next End Sub Private Sub NextPosition PosX As Integer PosY As Integer W As Integer figure out the movements of the robot works out the next movement from the current position Works out the degrees in the movement divides it into the relevant quadrant calculates the angle in its quadrant for the robot Calculates the tangent distance for the rovbot to travel This same code in the PIC was prohibitively large and comlicated so it is done here and sent to the PICc divides the angle in half the angle fits the hex 255 requirement the grid can only display corinates in about 2 degree increments anyway This with the tolerances of the robot should be sufficiently accurate for this purpose tan opp adj Dim x As Integer Dim y As Integer Dim CalcX As Integer Dim CalcY As Integer Dim TheAngle As Double Dim Tang As Single Dim TangBool As Boolean Dim HoldMe As String find where next point is PosX y PosY Ify 0 Then y 0 calculated direction from quadrant from current point If x gt xHold The
68. f the target age have limited dexterity and as such controlling a screwdriver and negotiating screws into specific holes may be an issue c Screwdrivers are sharp and pose a stabbing hazard The best of us have stabbed ourselves with a screwdriver so children unaccustomed to handling this type of tool would be very likely to injure themselves and or others Obviously if assembly is to be involved some adjustments parameters to the term assembly were required More thought with respect to the above issues showed the robot main chassis drive train and related parts needed to be supplied in an assembled format This would mean the parts that required assembly by screwing would need to remain attached permanently This revelation then left only one aspect of the robot that could be assembled onto the robot the electronic component board assemblies Possibly a way could be found to attached these so the construction aspect of the robot was still available Screwing and gluing were automatically removed from the list The implications of screwing were discussed earlier and carry the same issues in this instance Gluing is usually final so this was not a consideration After a lot of thought on the issue it became obvious that circuit boards all have a couple of common features Thickness and Rigidity 32 These meant if slots were cut into the robot the board assemblies could be easily pushed into these From there the cords
69. fortunately this addition adds an extra 10 to the price so the luxury was not considered important enough The Cheaper version was therefore chosen 2 7 Wireless Transmitting and Receiving There are two cheap alternatives for wireless communication between the robot and the computer base The first is the IR Infrared communication which entails a light emitting array and a receiver based in the Infra red spectrum The second is the UHF based transmitter Receiver set in the 434Hz range of this band 2 7 1 Infra Red Communication Infrared communication is very well documented and has been used for many years in applications from T V remote controls to Mobile Phone Computer interfacing The system is relatively easy to implement and requires extra circuitry in the form of a decoder encoder IC to use It is well proven in many instances but has disadvantages 26 Because it uses light the units communicating need to be fairly straight on to one another There is an angle of Transmission Figure 7 that allows communication but the Transmitter and Receiver must be facing each other to communicate If the Robot turned away from the Transmitter no communication would happen Robot Transmitter Figure 7 IR Transmission Angle b Infrared used outdoors or in high light conditions can be prone to false signals As Sunlight contains the Infrared spectrum also this could theoretically cause difficulty when the computer and Rob
70. g but generally they are an ideal plug in component for this project 2 3 1 Dinsmore Digital Sensor 1490 This sensor is the cheapest of the range It supplies a digital signal to the microcontroller that is bought to logic level with pull up resistors in the circuit The sensor is made from sub miniature rotor crystal in suspension with Solid State Hal Effect IC s Wiltronics 2005 This compass can therefore be incorporated into a design without the use of external or internal ADC circuitry The component outputs a basic 8 direction compass bearing of N S E and W The 4 output pins output logic 1 or 0 in regards to these directions NE NW SE and SW are produced by the overlap of two 20 directions For example North East would have the North Pin high and the East pin High 1100 There is also some settling time for a 90 swing but this shouldn t be a major issue as the robot shouldn t be moving at a great rate 2 3 2 Dinsmore Analogue Sensor 1525 This sensor is more then twice the price of the 1490 model but has substantial features over the later This component has 2 output pins that output separate analogue sine waves These can then be processed with either external ADC or the internal microcontroller ADC circuitry By comparing the sine waves heading can be defines down to the degree This unit has the same considerations as the 1490 in regards to polarity of pins and soldering time in regards to circuit dama
71. ge This compass is also damped so there is an up to 3 second delay for a 90 displacement 2 3 3 Dinsmore Analogue Sensor 1655 The 1655 has similar characteristics configuration and consideration to the 1525 It has a little faster recovery time then the later and is similarly priced The Dinsmore Digital Sensor 1490 was chosen for use in the project The main reason being that the demonstration of the 8 basic compass points is all that is required The others would do this more accurately but at around 80 for a single component the last 2 alternatives were way out of the price range of this project 2 4 Motor circuitry Selection A 6 Volt motor while being cheap brings its own issues in regards to control Controlling speed and direction of these motors is more complicated then plugging a few wires in and hoping for the best After investigation the best way to control a motor in relation to speed and direction is by incorporating a H Bridge into the design H bridge works by using electronic switches that let current flow in a particular direction across the motor Refer Figure 3 21 V Ve Figure 3 H Bridge simulation Turning one direction By changing the switching the motor will turn the other way Figure 4 V V Figure 4 H Bridge simulation Changed direction The other beauty of this format is that it can be incorporated with the PWM output from a Microcontroller to control the actual motor speed
72. gether with an 8 pin Header so the group plugs into a specific Port and relevant pins are correctly aligned Inserting the wrong board plug will just result in inappropriate behaviour in the robot Power is has been deliberately kept separate so there is no chance of catastrophic failure due to power being introduced into the wrong area This system will not of course stop a concerted attempt to put power into an incorrect spot It will make it easy for someone who is trying to assemble the system with limited knowledge doing accidental damage As discussed earlier similar areas are grouped together where possible The PortA group has the ADC dependant inputs of the Light Line following sensors and the compass inputs on it This is a grouping of directional sensors The PortB group has the inputs from the LDR and the Emergency button Both of these peripherals fire interrupts on the P1c16F877A when actuated so are necessarily on PortB which has this option available The PortC group houses the Servo control H Bridge its Enable control the Motor Directional control and the Received data from the computer interface The PIC16f877A PortC carries motor functions in the form of PWM generation and the Receive transmit UART area Grouping the Motor Direction and the Servo control in the same area utilises this Port to its fullest The PORTD area houses the controlling of the LCD interface and the Music output board 42 Chapter 5 Softw
73. grid navigation would be expected to b Each increment on the graph represents 10cm 100mm this needs to be remembered because the robot will hit any objects in or falloff surfaces that are in its path This format of the robot does not have these external collision sensors The buttons have the following functions a Clear Grid Clears the grid and all the variables related to any previous grid movement b Program Bot Sends the coordinates to the Robot so it can start to navigate c Exit Returns to the Main Menu 5 2 4 Compass Interface Dialog This Dialog Figure 21 allows Compass Coordinates to be entered via the compass point buttons A Line appears on the compass screen and the coordinates are displayed in the left list box so the results can be viewed as both a line direction and as the compass bearing Pressing the C Button cancels the previous points The lines can be cancelled back to the first point Compass tJ n North North East East South Program Bot Figure 22 Compass Dialog 46 The function buttons have the following options a Program Bot Sends the set course to the Robot b Exit Reloads the Main Menu 5 2 5 Shapes Menu Equilateral Triangle Hexagon pentagon Heptagon Octagon Exit Figure 23 Shapes Menu Scalene Triangle Square Rectangle The shapes menu simply sends the command to the Robot to
74. h the prices they were purchased for UGN3503U Hall effect x 2 BC557 transistor 7805 Voltage Regulator Dinsmore 1490 Compass LCD Display 4 0 Mhz Crystal TX434 RX434 L293D H Bridge Driver Max232 LM833 OpAmp 741 505 Hex invertor PICI6F877A LDR x3 470 uF electrolytic cap x 2 1 uF electrolytic cap x 5 10 uf electrolytic 0 022uf Ceramic x 2 0 01uf Ceramic LED x 4 Trim Pot 200ohm x 2 Cutting Board DC Motor Tamiya Super Avante Kit Servo 33 tooth metal cog x 2 9 90 0 26 0 99 27 95 19 96 3 95 6 00 8 00 4 95 5 34 2 40 0 60 12 95 3 63 1 10 1 25 0 20 0 28 0 28 1 00 0 64 8 00 1 38 9 66 19 95 16 00 57 Jaycar Jaycar Wiltronics Wiltronics DSE Jaycar Oatley Electronics Oatley Electronics Wiltronics Wiltronics Jaycar Jaycar Jaycar Wiltronics Jaycar Jaycar Jaycar Jaycar Jaycar Jaycar Jaycar Supermarket Wiltronics DSE Hobby Shop Hobby Shop 8 pin Header x 4 3 80 Jaycar 8 Locking Headerx 4 1 60 Jaycar Jumper shunts 1 45 Jaycar 40 pin terminal strip 0 65 Jaycar Piezo 4 10 Jaycar 40 pin IC Socket 0 70 Jaycar 16 pin IC Socket 0 34 Jaycar Resistors x 18 0 90 Jaycar Switches x 2 1 80 Jaycar Ribbon Cable 1 m 2 89 Jaycar Terminal Block 2 98 Jaycar 500000 Candle Power torch 19 95 Car Store PCBoard 16 98 DSE 2 pin Header x3 1 50 Jaycar 3 pin locking Header x 3 0 30 Jaycar Total 222
75. hod of motion and steering For this project though the 3 wheel robot method was chosen for 3 reasons 1 The Tamiya Track model is built from moulded plastic and hence may not stand up to the anticipated abuse during use 2 The interesting construction design and programming aspect of the build three wheeled 3 The difficulties in designing a substantial Track system as apposed to the three wheeled system 3 2 Chassis Material Selection Once the chassis design was decided upon a suitable material was required to build it from The following materials were considered 3 2 1 CD Ply CD ply is a common building material readily available at hardware shops and timber stores It is relatively cheap lightweight and reasonably easy to work Its main downfalls are 29 It is timber and as such can have very raw edges or splinters This can be a danger for children or people handling the robot There also could be a danger of injury from splinters if the robot brushed past someone while moving across the floor b Ifthe robot was flexed excessively as in the case of someone stepping on it though plywood is relatively flexible it may splinter and injure someone c CD ply is often only available in full sheet size This would make it rather expensive to make single units d Ply is not very strong in its end grain so screwing or fastening that involved fixing into the end grain would be less then satisfactory For these r
76. icCompass PSet x y PicCompass DrawMode 13 CmdOption 0 Left FrmCompass Width CmdOption 0 Width 300 CmdOption 0 Top PicCompass Height FrmCompass Height PicCompass Height CmdOption 1 Height 2 3 CmdOption 1 Left FrmCompass Width CmdOption 1 Width 300 CmdOption 1 Top PicCompass Height FrmCompass Height PicCompass Height CmdOption 1 Height 3 End Sub Private Sub DoMultiple sends the list of controls to the PIC16F877A Dim A As Integer set baud rate bit length etc MSComm1 Settings 2400 N 8 1 set port number MSComm1 CommPort PORTNUMBER CoOrd XX Hex 254 For 1 To XX TimerCompass Interval 10 10 m s TimerCompass Enabled True Do wait for tht timer DoEvents dont lock up the computer Loop Until Done True Done False reset the values TimerCompass Enabled False If MSComml PortOpen False Then open the port MSComml PortOpen True End If send the details CoOrd A ROBOTID amp CoOrd A if need to send code each time MSComm1 Output CoOrd A If MSComm1 PortOpen True Then close the port MSComm1 PortOpen False End If Next End Sub 93 Private Sub Form Unload Cancel As Integer CmdOption Click 0 End Sub Private Sub MSComm1_OnComm Done True End Sub Private Sub TimerCompass_Timer Done True End Sub 94 F 3 Active Comm Port Find FrmPORT Checks each port to see which are active
77. ill give real world applications for the child to tie together with the theory they have previously learnt These combinations will allow this unit to become a valuable tool in the teaching environment 1 3 Research with teacher and children It appeared obvious that any project targeting children and teachers was doomed to failure unless the target users were consulted early in the planning stage of the project This was therefore an important first step and was implemented early in the process The initial approach was to send a letter of outline to the principal of local school This was a requirement of the Department Of Education From here the relevant teacher was approached This initial research was a two pronged approach Firstly input on what the average teacher would require to integrate the finished product into the everyday classroom situation was required Secondly the children needed to be consulted as to what they might find useful and or interesting if this sort of device was going to be used by them in the classroom To implement the teacher stage of the project an outline of questions was put together The idea was not to be too specific in case the tone and expectations of the questioning skewed the outcome By sticking to topics and allowing the teacher to run with the ideas a plethora of information was collected This method on reflection took the interview far beyond what was initially perceived as possible par
78. ing present The first part of the child s questionnaire Appendix B a came about on the idea that the robot might be assembled from a group of modular boards that could become a class activity in itself It involved measuring the hand span of each child so that an average or as was eventually chosen the smallest hand size could be found The results show that by making the boards a maximum of 75mm on the small side it would allow all children of this age group to comfortably grip the boards and assemble them The questionnaire Appendix B b was incorporated to see what the children thought would be interesting or useful The questions were meant to be slightly leading to narrow the field off possible answers Unfortunately as W C Fields indicated never work with children or animals so the questions lead to some interesting answers A full rundown can be found in Appendix B c A summary of the answers is included below This research greatly helped set the project specification Topic Girls Boys Motion Walking 56 Wheeled 28 5 Time to Assemble More then 30 mins 50 30 mins 38 Appearance Sci fi robot 57 Sci fi robot 31 3 Figure 1 Brief Overview of Child Questionnaire 13 1 4 Conclusions Chapter 1 As any parent knows cost is a real factor in today s free education In the long run parents through organizations like the P amp C Parents and Citizens Association supply th
79. is shown in Appendix E Drawing 5 3 3 4 Drive mounting The motor and shaft assemblies required proper mounting so the robot could move and the whole assembly remain stable This assembly also needed to be robust enough to handle repeated use and interaction with children This posed the question what to build the assembly from Metal would be the ultimately choice but as discussed earlier there are issues with manufacture and weight especially for a homebuilder With a little thought Polypropylene because the obvious choice for all the reasons discussed earlier for the chassis The use of gearing and shafts meant the motor and wheel assemblies would be mounted separately Considerations for motor shaft mounting a The mountings would be as compact as possible 34 b The mountings for the shaft should incorporate mountings for the motor as well c The parts should be easy to construct With this in mind the parts were laid out in and the mountings were designed by trial and error Technical drawings of the Drive Mountings can be viewed in Appendix E The mountings were designed from the centre out The central mountings were designed using the circular end on the motor for mounting and the length of the main shaft Item 4 on sheet 3 was the final designed to hold these The other end of the motor now needed to be mounted With a small pinion gear directly mounted on the motor an intermediate cog also required mounting As a
80. k of the sensor it can be made to detect the presence of metal or its absence Hall affect sensors are also quite cheap and reasonable robust electronically Surprisingly the Hall effect sensors were sensitive enough to detect very fine teeth on small sprocket By using a small metallic sprocket with a large number of teeth on the main drive shaft connected to the wheels minute 18 variations in position can be detected This happens as the teeth of magnetically effected metal sprocket move past the sensor Though this method worked out to be moderately expensive its ease of implementation in this situation and minimal requirement of skill for inclusion or adjustment made it the most obvious choice for this application 2 2 Motor Selection Moving the robot about required careful consideration due to size constraints of the robot Whatever was chosen needed to be small enough to fit under the robot without making the robot look top heavy or unstable It also required suitable mounting so they remain in situ during the use and abuse the robot would suffer in a classroom environment 2 2 1 Stepper Motors Stepper motors are particularly powerful and by their very makeup incorporate the ability for position sensing This would make then ideal for this sort of action Stepper motors are inherently quite bulky in particular the cheaper ones available The bulk of the stepper motor raised the robot significantly with the gir
81. king Educational Robot BETTY Brilliant Educational Technology Truthful Yacker CISER Children s Safe Educational Robot Figure 34 Robot Names Boys 2 Girls Talk Play Music Be controlled gt Avoidance Follow Line Steer Remote Voice Activated Walk Sideways Do School Work Clean Cook Serve Meals Autonomous Answer the Door Pick up stuff Walk up stairs Walk on rough Dance StoreInfo Fold Up off Beep when finished Bark Read write See Type Climb Help Kids Learn Play Games Fly Skate Crush Cans Run Xray Vision NI DO Go BIL RL NINI I DN A House Work Help Reward you Make animal sounds 67 Swish Tail Flash lights Be water Proof Learn Act Real Hug Be Fast Flash Lights Interact Sing Gymnastics Transformer Tell Jokes Jump Sleep Weal Backwards Sense stuff on floor NI NI N Figure 35 Children s Robot Action Suggestions 68 Appendix C Low Voltage In System Programmer SCHEMATIC Connection Tabie for Panter Port LPT E
82. lation return GridEnd movlw 0x03 movwf LCD call DoLinel GridStop goto GridStop 107 H 4 Motor Code Excerpt 2 Motor codes Contains the codes for the motiors Including forward Reverse Left Reverse right and full stop StartMotors Sets both motors to forward moving a value to CCPR1L and CCPR2L sets the speed StartMotors MOVLW d 125 movwf CCPRIL MOVLW d 125 movwf CCPR2L MotorPort BSF PORTC 3 BCF 4 5 return ReverseMotor this enables the HBridge this set to forward this sets to forward Chooses which Motor to reverse according to the Direction boolean ReverseMotor see which motor to reverse call AddPerimeter btfsc Direction 0 Goto RevLeft RevRight Moves the speed value into the Right Motor Sets the Reverse port to high so the motor spins backwards RevRight movlw 4 125 movwf CCPRIL BSF 4 BSF PORTC 3 set high to reverse this enables the HBridge 108 RevLeft Moves the speed value into the leftt Motor Sets the Reverse port to high so the motor spins backwards 2 2 RevLeft MOVLW d 125 movwf CCPR2L BSF PORTC 5 set to reverse BSF PORTC 3 this enables the HBridge return TurnLeft This code is used by all of the movement code The servo is turned and the bot pasues while this happens the distance is rloaded and the bot counts the pulses TurnLeft movlw d 3 load a left turn movwf ADPos
83. les being plugged in backwards While there was little chance of damage to the electronics it creates a debugging issue that might not be easily rectified by an inexperienced user Another addition was a reset button so the Microcontroller could be reset in case of error or just to restart a sequence of code The reset button could be easily left out of production assembly without detriment to the circuit The power supply circuitry was chosen because it was envisioned that the main board would also supply power to other parts of the robot Early trials of this showed the microcontroller was prone to reset especially when a high draw item like a motor was changing direction This was rectified by incorporating a couple of large 470uF capacitors across the feed and supply pins of the LM7805 to smooth the power at the demand time Schematics are provides in Appendix E for this main board and a picture of the mainboard can be seen with Figure 11 37 40 Pin PDIP MCLR VrP 1 40 RB7 PGD RAO ANO 2 39 RB6 PGC lt 3 38 RB5 RA2 AN2AnErFOVREF 4 RAS ANSAVAEF a 5 RA4 TOCKI C1OUT L 6 RAS ANA SSIC2OUT 0 7 REO RD ANS RE1AWRYANG 9 RE2 CS AN7 10 Yoo 11 37 RB4 36 RB3 PGM 35 RB2 34 RB1 RBO INT 32 4 31 Vss 30 RD7 PSP7 29
84. make the Stepper motor operate This order means that it is quite easy to track the current position of the motor and how far it has travelled since the pulses started The disadvantages of this style of motor a They are rather bulky in size This means the size of wheels needed for the vehicle would be fairly large to compensate for the size of the stepper b This size also means there are difficulties in mounting them to the chassis c Stepper motors have multiple wires in each unit depending on the amount of steps that are available from the unit Connecting these units would require either multiple pins on the Microcontroller or a specific controller Because of these issues Stepper motors were discounted for this application 2 1 5 Hall effect sensors Modern Hall effect sensors are commonly used to detect the presence of metal or magnetic fields Some models are so sensitive to magnetic fields they are capable of detecting the magnet fields of the earth and most electronic compasses are based on these In this instance the Hall effect sensors would work by detecting the magnetic fields created by the presence of teeth on a metal cog The sensor emits a voltage or no voltage in relation to the presence of the metal teeth To facilitate detection a magnet is glued to the back of the sensor This produces the magnetic field with the presence of a metal tooth By positioning the North or South of the magnet against the bac
85. more expensive parts of the robot Considering at least three would be required in the final design they quickly became a substantial portion of the final cost b Technical Skill An amount of mechanical skill is required to pull down a servo and adjusted it to produce a 360 revolution It is also easy to damage the servo while doing this Even in a short run situation considerable time would be required to manipulate a number of units This labour content would add greatly to the cost of the final unit The above considerations meant the Servo was removed as a choice for the final unit 2 2 3 Small DC motor and gear assembly Small D C motors that run on voltages up to 6 Volts D C are readily available quite cheaply Flat versions are available and avail themselves to easy mounting Cheap gear trains are also readily available quite cheaply for this size motor This flat DC style motor was chosen for the project because of the final price of around 1 50 each They also are powerful enough to move the lightweight robot around The flat version of these also allowed easy constraint within the mountings of the drive train 2 3 Electronic Compass Selection There are 3 models of electronic Compasses readily available here is Australia They are all suppled by Wiltronics Electronics in Victoria and all are variations on the same technology The compasses have special requirements to stop damage from incorrect pin orientation and or solderin
86. n see if in first or fourth quadrant CalcX x xHold calculate x distance If y gt yHold Then Quadrant 1 select quadrant CalcY yHold calculate y distance End If If y yHold Then Quadrant 5 CalcY yHold calculate y distance End If If y lt yHold Then 87 Quadrant 2 select quadrant CalcY yHold y calculate y distance End If End If If x xHold Then CalcX x xHold calculate x distance If y gt yHold Then Quadrant 1 select quadrant CalcY yHold calculate y distance Else Quadrant 3 select quadrant CalcY yHold y calculate y distance End If End If If x lt xHold Then x is less so has turned around CalcX xHold x calculate x distance If y gt yHold Then Quadrant 4 select quadrant CalcY yHold calculate y distance End If If y yHold Then Quadrant 6 select quadrant CalcY y yHold calculate y distance End If If y lt yHold Then Quadrant 3 select quadrant CalcY yHold y calculate y distance End If End If calculate actual tangent of triangle Tangent Sqr CalcX 2 CalcY 2 Tangent Format Tangent calculate the angle offset in degree If CalcX lt gt 0 Then If CalcY lt gt 0 Then TangBool True Tang CalcY CalcX End If End If If TangBool lt gt True Then Tang 0 End If TangBool False TheAngle Atn Tang TheAngle TheAngle 180 Pi TheAngle Round TheAngle add Quadrant to angle Sel
87. n be seen that adding all the digital amounts 128 64 32 16 8 4 2 1 256 This is how numbers and letters are sent via modems In this application using the binary representations of 0 to 180 for the halved degrees The value can be sent in one 8 bit data bit represented as 175 and 0 5 and doesn t need to reassembled in the PIC16F877A from two passes as a number like 359 would need In reality the 180 degrees would be represented as 0 but to demonstrate the decimal number 180 would be represented in binary as 10110100 in its 8 bit form 5 3 3 The Compass code The compass code Appendix F 2 uses the picture box again to show the progress of the robot A representation of a compass is used for the navigation buttons As the buttons are pushed Figure 21 a line is drawn on the screen and the compass directions are placed in the list box at the side The compass directions are converted into a 4 bit code representing the expected input from the compass on the PIC16F877A This is explained more thoroughly in 5 4 2 Incorporated in this code is a direction history so a sequence of instructions can be deleted back to the initial starting point 49 5 4 PIC16F877A Coding The coding format selected for programming the PIC16F877A is ASSEMBLER Assembler enables a compact code that can even allow code sections to be timed for important functions Code written in it can be easily optimised It was chosen for this reason Assembler
88. ng code The code Appendix H 3 firstly receives the list of angles and tangents produced in the Visual Basic code as discussed in 5 3 2 Each piece of data is stored in the memory area range of AOh to FFh Figure 26 This allows 95 entries or 47 different directions to be added The code then loads the first angle The angle data is halved to see if the angle of movement is greater or smaller then 90 this represents a full 180 degrees Depending on the result the robot wheel direction is set The original angle is then doubled to return it to its true 360 representation The robot is reverse on one wheel until the angle is correct The Hall effect Sensors detect the movement By taking the distance at the centre of the two wheels it was calculated that the sensors would be able to detect approximately 1 5 degrees of change The code counts the degrees moved in this method and stops when the required distance has passed The tangent amount is then loaded from memory and the robot moves forward counting the Pulses from the wheels The robot is set to move 100mm for each space on the grid 66 pulses are equivalent to 100mm So 66 pulses from the sensors are counted for each unit until the tangent amount has been reached 51 PIC16F87XA FIGU
89. nics to produce quality music Most of these methods are quite involved and appeared to be outside the scope of this project An easier way to do this was required It was noted during this research that it 1s possible to produce a beep in a piezo speaker with minimal peripheral electronics Bringing music back to basics one must realise that providing a vibration at a particular frequency produces a particular musical note In different musical instruments this is done in various ways stringed instrument vibrates its strings at the particular frequency to form a note or a chord where as a wind instrument might vibrate a reed to produce the required sound waves Likewise a stereo sends a particular vibration to a speaker to produce each note With this mind research focused on discovering the frequencies for individual musical notes The theory being if the individual note vibrations could be produced from the Pic16f877A music could be played by inputting the notes from sheet music The internet site http www phy mtu edu suits notefreqs html deals with the physics behind musical note frequencies discussing the frequencies in Hz and the wave lengths in cm s Considering the plethora of information on hand at the site and trying to put it into perspective for this project the first idea was not 53 to try producing symphony quality music With this in mind all notes except the Major scale could be ignored This would leave the
90. nt out via Receiver pin 12 R1 out The output then goes to the Data pin on the TX434A Pin out available on CD An extended track on this board also acts as an antenna to save having an external antenna The only other connections required are the power and the earth 4 7 LCD Module The LCD PCBoard is also quite unremarkable and only used to mount the LCD module a potentiometer and the header to interface to the PIC16F877A The potentiometer is used to adjust the contrast on the LCD The potentiometer ties the voltage the ground and the contrast pins together Adjusting the potentiometer adjusts the contrast accordingly D 8 1524109 Sy Dea 420123 2285 Figure 16 Hitachi 44780 LCD Pin out Hitachi 2006 41 The LCD has been set up in the 4 configuration so only 6 pins are needed to run the LCD and send the required characters to it The Read Write pin is tied to the VCC Line so it is easy to write all of the time Lines to the Register Select Eclock D14 D13 D12 and D11 are all that is necessary then to interface the LCD module and the PIC16F977A together 4 8 Stop Button Circuit The Stop button circuit is simply a mount so the button can be pushed if the unit is eminent danger or needs to be instantly stopped 4 9 Connecting it together The schematics in Appendix D show the connections of each electronic module to the Mainboard housing the PIC16F877A Board groups are connected to
91. ot were legitimately trying to communicate c Range 15 also an issue with Infrared with normal ranges in low light situations being on several metres and IrDa Devices usually having ranges up to More information can be found at http www irda org the home page of the Infrared Data Association Web Page 2 7 2 434 Hz UHF Wireless Communication This method uses the 434 Hz UHF frequency which has been set aside for this style of communication device In difference to the Infrared system the 434 Hz wireless UHF transmits in all direction at once so the robot does not need to be facing the unit The system can also have a range of up to Ikm with the right power source The modules for this are incredibly easy to use in an electronic circuit The disadvantages of this system are a Just as the multidirectional properties of 434Hz wireless are a bonus they also become an issue when multiple units are operated in the one area Where an Infrared unit could be aimed at a particular robot all robots receive the signal from the 434Hz UHF system This would require workarounds in the software b The full effect of radio waves and the human body is still a grey area of science and medicine Prolonged exposure to these waves could cause a health hazard The time of exposure in reality should be seconds in an hours use but this is still a small issue 27 Both methods use similar electronics to interface and the cost of implementing both
92. oulded cover for the robot This would finish the robot and allow parts like the LCD to be mounted on the robot Plastic moulded chassis parts would also be a plus b Have some sort of touch bumper sensor designed This would stop the robot bumping into things and possibly causing damage It could also possibly be used to stop the robot from falling off a table for example This could also be in the form of an Infrared radar system c USB interface At the start of the project the use of USB was tossed around for the interfacing There was concerned about USB licensing for a marketable product though Over the last 12 months USB has become more prevalent and many new computers no longer have the serial or parallel ports supplied It will probably be a couple of years before Schools get the newer computers but this is an issue of obsolescence Not addressing this would make this final product less then attractive 59 References Allegro 2006 3503 Ratiometric linear Hall Effect sensors Allegro USA Dinsmore Compass Specifications 2006 Wiltronics electronics Retrieved 11 December 2006 from http www wiltronics com au datasheets dinsmore pdf Fairchild Semiconductor 2006 LM78XX LM78XXA 3 Terminal Positive voltage Regulator Fairchild USA Hitachi 2006 HD44780 U LCD Hitachi Japan Kim Dr C 2006 Embedded Computing with PIC 16F877 Assembly Language Approach Self Published Purchased July 2006 f
93. ove materials Polypropylene was the stand out choice Although the in class assembly activity would have to be carefully reconsidered it offers the best all round properties including safety The best aspect for testing is that it is readily available at the local supermarket in the form of cheap cutting boards This made the product readily available for testing or the amateur builder without having to source it from a specialist plastics supplier Plastic also gives the product a more professional finish then timber and metal 31 3 3 Chassis Design There was an idea in the early stages of the project to include basic assembly into the design as an option for the children This would give a teacher the opportunity to incorporate this as a class activity Assembly would also give the children a feel for the important hands on aspect that is so relevant to modern engineering 3 3 1 What is Assembly The choice of Polypropylene as the chassis material bought forward the above question If the robot was to be in several parts and these parts needed to be to be reassembled how would this happen The most obvious method of assembly would involve screws Screws are readily available easy to use and have a proven ability as a fastener Screws though instantly cause several issues a Polypropylene while having some very good properties is a plastic and as such has issues with threading when it is screwed into b Children o
94. peEnd call EEPROMRead movwf Tangent call FindAngle movf MemVar w movwf Angle STATUS Z call StartMotors btfss STATUS Z call ReverseMotor movf Angle w straight sublw 0x00 STATUS Z goto Str8 btfsc Direction 0 call btfss Direction O other way call TurnRight get the distance calculated angle set motors for ahead Set the motor to turn the bot check to make sure we are going so we dont need else below choose which direction to turn make sure doesnt go straight back the 112 Straightens the Servo Deletes turn in for Starts to step out the side Str8 movlw servo straight movwf ADPos clrf DistLeft sremove evidence of the turn call OneSecond stop while wheel straightens clf DistRight call StartMotors go forward call Drive goto SetShape ShapeEnd Stops motors LCD Music ShapeEnd call StopMotor do some LCD magic movlw 0x02 movwfLCD call X DoLinel Stopme goto Stopme Loads the EEPROM memory Positions for each shape 2 2 movlw 4 0 banksel EEADR movwfEEADR goto SetShape SetR movlw d 9 banksel EEADR movwf EEADR goto SetShape SetEQ movlw d 18 banksel EEADR movwf EEADR goto SetShape SetSC movlw d 25 banksel EEADR movwf EEADR goto SetShape 113 movlw d 32 banksel EEADR movwfEEADR goto SetShape SetHex movlw d 45 banksel EEADR movwfEEADR goto SetSh
95. pins bcf Compass 0x01 we not interested in bcf Compass 0x02 bcf Compass 0x03 swapf Compass f swap the high and low bits return CompassEnd movlw 0x01 movwf LCD call DoLinel CompassStop goto CompassStop 104 H3 Grid code Excerpt Grid code Reads the Compass points and tangents from Memory one at a time 2 The robot moves around the required angle 2 then moves the required distance n the direction prints the perimeter and sings at the end plays music 2 OutPut none 2 Begin Grid Sets all required Ports and registers so the robot can interact 2 BeginGrid call InitMemory call SetHall call SetTMRO TMRO call SetTimerl call Init motor Set the call StartInt Start Global Interrupt Perimeter Perimeter 1 Loads in the Tangent and The new Angle Moves the robot the required angle then sets the distance to travle on the tangent GridGo movlw servo straight movwf ADPos call movwf Tangent read in tangent distance movlw OxFF see if grid is finished subwf Tangent w skpnz goto GridEnd call movwf MemVar read in Angle call FindAngle 105 movf MemVar w calculated angle movwf Angle STATUS Z call StartMotors set motors for ahead btfss STATUS Z call ReverseMotor Set the motor to turn the bot movf Angle w check to see if we are to go striahgt sublw 0x00 btfsc STATUS Z
96. plethora of addition information on how to use built functions and examples of operation for its entire range of Microcontrollers The final choice came down to two microcontrollers from this Range 2 5 1 PIC16f628A The PIC16f628 is an 18 pin microcontroller that offers two banks of 8 pins called PORTS that are accessible for input and output to peripheral electronics The chip also offers the following built in functions as standard 4 Analog input pins RX USART Asynchronous Receive capability TX USART Asynchronous Transmit capability A Synchronous Data Input pin A Synchronous Clock A Capture In Compare Out PWM Out pin An Oscillator In External Clock In Pin An Oscillator Out Clock Out Pin A MCLR Master Clear pin A Timer0 clock input A Timer oscillator output A Timer oscillator input A Serial programming data Pin A Serial programming clock Pin A Low voltage programming input A External interrupt Pin This CPU uses a RISC format for its instructions and in this case a small set of 35 instructions for programming The speed of the microcontroller can also be accurately controlled by using an external crystal This means timing for specific peripheral interfaces can be timed to precision It has a 2k Flash Program Memory 224 byte Ram data Memory and 128 byte EEPROM Data memory 24 This chip also has the option of LVP Low Voltage Programming where the chip can be easily programmed with the relevant code via 5Volts
97. plication 40 4 5 H Bridge Circuitry The H bridge circuitry is quite unremarkable because the L293D takes all of the complication out of the circuitry All that is required besides the power and earth is the PWM signal from the Microcontroller for each side and logic high of 5 Volts to enable each side of the H bridge controller In this instance they are connected together at the PIC16F8767A because when the Motors to be shut off both motors will be disabled at once As mentioned before the PWM is supplied from pins and RC2 the CCP2 and outputs This is sufficient to supply the power to actuate the L293D The output is simply 2 power lines that connect straight to the motor 4 6 434 Hz Transmitter and Receiver The Receiver module is a straightforward connection only requiring power an earth and the data out line A long track on the board was created to act as the antenna to save having an external antenna The Transmitter module is a little more involved with the inclusion of a MAX232 IC Texas Instruments 2006 Data Sheet available on CD incorporated into the design This IC converts the RS232 output from the Serial Port to Logic levels for the PIC16F877A as discussed in chapter 2 8 The connection to the MAX232 is a little back the front from the expected The inputs and outputs are in relation to the IC itself so to transmit a signal from the computer the signal goes into the Received pin 13 R1 In and is se
98. prohibits this This style of position sensing was therefore rejected 2 1 2 Gray Encoder wheel The Gray encoder wheel is a particularly simple design where a wheel is marked with shaded and white areas of various lengths circumferentially around a circle The current position in relation to the sensor is determined by an optical sensor array detecting the light or dark areas underneath By having three or four senses in alignment the current position is output as a binary sequence depending on these areas underneath Figure 2 3 bit Gray Encoder Wheel Rotary Encoder 2006 16 A 3 bit encoder as shown in Figure 2 produces the following binary code as it turns clockwise you move counter clockwise starting at the 000 001 011 010 110 111 101 100 Though this is particularly effective with a position sensing in this particular application there are several difficulties in its implementation a The size constraint of the encoder wheel is around 20 mm diameter This would mean that each particular encoder section would be particularly fine making it a little difficult to produce This could of course be worked around by supplying the encoder as a sticker b The electronic componentry of the reader would be very small Electronics miniaturisation 18 obtained at a cost An array of sensors of this size would become quite expensive especially if more accuracy was sought c To gain accuracy the wheel would need more en
99. raph and grid points could only give 2 accuracy As result it was possible to halve the angle before sending it to the robot This was done to fit within Hexadecimal constraint of Hex FF or 255 decimal Dividing the angle in half means the angle can be sent in one 8 bit burst and later doubled at the Robot end because 360 divided by 2 is 180 Figure 24 demonstrates the constraints of how a single character is sent from the computer to the Robot 48 Mark 10V sat 1 2 3 4 5 06 7 59 10V Space Figure 25 RS232 Protocol Form Kim 2006 The diagram above shows using the common 8N1 format 8N1 signifies 8 Data bits No Parity and 1 Stop bit format The RS 232 line when idle is in the Mark state Logic 1 A transmission starts with a start bit which is Logic 0 Then each bit is sent down the line one at a time The LSB Least Significant Bit is sent first A Stop bit Logic 1 is then appended to the signal to make up the end of a transmission Kim 2006 in layman s terms The PICI6F877A expects to see a zero to start then a combination of 8 ones or zeros to make up the data then a one to say it is finished The combination of 8 ones and zeros are where the constraint comes in Figure 25 demonstrates how the largest binary 8 bit number is represented and its equivalent binary representation Binary and Decimal equivalents 1111 1111 128 64 32 16 8 4 Figure 26 Binary Decimal Equivalents It ca
100. reen as a representation stores the Hex value as would be expected by the PIC16f877A from the compass to save processing Dim Skipthis As Boolean Dim F As Integer Select Case Index Case 0 north PicCompass CurrentY PicCompass CurrentY MoveMe LstDirection AddItem North CoOrd XX 8 b 1000 north Case 1 south PicCompass CurrentY PicCompass CurrentY MoveMe LstDirection AddItem South CoOrd XX amp H2 b 0010 South Case 2 west PicCompass CurrentX PicCompass CurrentX MoveMe LstDirection AddItem West CoOrd XX b 0001 West Case 3 east PicCompass CurrentX PicCompass CurrentX MoveMe LstDirection AddItem East CoOrd XX amp 4 b 0100 East Case 4 north east PicCompass CurrentY PicCompass CurrentY MoveMe PicCompass CurrentX PicCompass CurrentX MoveMe LstDirection AddItem North East CoOrd XX amp HC b1100 North East Case 5 southeast PicCompass CurrentY PicCompass CurrentY MoveMe PicCompass CurrentX PicCompass CurrentX MoveMe LstDirection AddItem South East CoOrd XX amp H6 b O110 South East 90 Case 6 southwest PicCompass CurrentY PicCompass CurrentY MoveMe PicCompass CurrentX PicCompass CurrentX MoveMe LstDirection AddItem South West CoOrd XX amp H3 b0011 SouthWest Case 7 northWest PicCompass CurrentY PicCompass CurrentY MoveMe PicCompass CurrentX PicCompass CurrentX MoveMe LstDirection AddItem North Ea
101. rementing and decrementing the PWM steering pulse between 7 and 18 by 1 This represents full left and full right turn with 13 being centre Once the maximum or minimum is reached further presses are ignored A standard computer has a Type Matic Rate Characters second of 6 with a Type Matic Delay Seconds of 250ms This means the PIC16F877A and the computer will interact a maximum of 6 times in a second At this rate the Servo will turn from full left to full right in around 2 seconds and go from start to full speed in 3 seconds 56 Chapter 6 Conclusion This chapter brings together the project with respect to the previous chapters Discussed here will be the achievement of objectives and potential for further work This project has been very difficult at times but has been incredibly rewarding and has pushed personal boundaries aside It has truly been educational The project has allowed the demonstration wide of variety of skills and topics from programming to design both electronic and mechanical Totally new skills like methods of designing and manufacturing PCBoards had to be learnt and demonstrated The author designed and produced all of the electronic circuits used and tested Circuit board designs designed on PCB123 are included on the CD This project was truly a worthwhile educational experience 6 1 Final Cost The final cost of the components is listed below The items from the various suppliers are listed wit
102. result Item 2 on Sheet 1 was designed The drawing shows how the flat motor shape was used to hold the motor in the mounting The Wheel Mount Item 2 of Sheet 2 was designed to hold the other end of the intermediate cog and the wheel end of the main shaft with space for its cog The full assembly can be seen in Appendix E Drawing 7 and in FIGURE 9 Figure 9 Drive Assembly Aluminium rivets were used as bushes for the drive with the pull removed and the intermediate cog shafts with the pull in and trimmed There use was to stop any wear in the plastic that spinning shafts may cause 3 3 5 Steering As was indicated above the Robot was to be three wheeled In this configuration the Servo would be mounted inverted in a hole cut in the chassis 35 Appendix E Sheet 5 7 The wheel is then mounted onto the Servo Horn a bracket Appendix E Sheet 6 Item 8 This allowed an easy wheel configuration that was easy to interface with the Electronics 3 3 6 Peripheral Mountings The final mounting consideration was the Line following PCBoards The nature of this board meant it requires some shielding from incidental light and it needs to hold the board low enough that the line can be detected To accommodate this a redesigned version of one the mountings for the drive was produced Appendix E Sheet 2 Item 3 The new design has a slot along its length that allows the board to slide into and be held while in operation
103. rochip 2006a The full datasheet is also available on the CD The Pic16f877A is available in a 40 pin configuration This with the added functionality and memory size made this chip the ultimate choice for the functionality that was intended to be included in the final product 25 2 6 LCD Selection At the time of research there were only 2 LCD displays available at a reasonable pricing Both were clones of the Hitachi LCD Controller range Several other models have appeared on the market since then and will not be reviewed in the text The first includes the following functions Control Refresh and Display functions executed by a dedicated on board controller Dot Matrix 16 Character x 2 Lines Module Full 160 characters JIS font set Low Power Consumption 5V Power Supply 5x 7 Dot Matrix with Cursor The controller also allows the creation of the new characters It is also programmable by either 4 or 8 bit mode The 4 bit mode allows the LCD to be enabled with as few as 6 inputs from the microcontroller This information and more is available at http www dse com au cgi bin dse storefront 458b31 df03fe8ca4273fc0a87f9c0754 Product View Z 4172 They are relatively easy to use though special steps and timing are required for interaction An excellent source of information for this LCD is at http www myke com Icd htm The second LCD display incorporates the above features with the added functionality of being backlit Un
104. rochip including distance recognition motion light and line following spatial recognition Create relevant interfacing components to implement computer robot normal functioning and remote control As time permits 8 Research methods to shape plastic 9 Create a shaped plastic exterior AGREED Student Supervisor Date 62 Appendix B School Research a Hand Measurement Measurement mm B G Measurement mm B G Measurement mm B G 63 b Child Questionnaire Grade 6 and 7 Robot Design Questionnaire Please circle one 1 of the following in each Question 1 Are you a a Boy b Girl Considering a small robot about the size of a tissue box that you would be able to control using a computer 2 How do you think the robot should move a Walk b Roll on wheels c Slide d Other Please specify 3 If you had to assemble the robot how long would you like to spend putting it together before you could use it a 5 mins b 10 mins c 20 mins d 30 mins e Other please specify 4 What should the robot look like a A science fiction Robot b A car c An insect d Other please specify 5 What should the robot be called This should be a name like KeFER Kid Friendly Educational Robot 6 What else would you like th
105. rom http www hirstbrook com book html McManus C 2006 The Complete BJT Circuit Retrieved December 12 2006 from http www mcmanis com chuck Robotics tutorial h bridge bjt circuit html Microchip 2006a 16 6274 6284 648 Datasheet Microchip USA Microchip 2006b PICIGF87XA Datasheet Microchip USA Motorola 2006 SN54 74LS05 Hex Inverter Motorola Semiconductors USA Music Scores com 2006 Retrieved December 20 2006 from www music scores com ON Semiconductor 2006 LM833 Low Noise Audio Dual Operational Amplifier ON Semiconductor Japan Optoelectronics 2006 CDS Cell VT935G OptoElectronics USA Phillips 2006 BC556 BC557 PNP General Purpose Transistors Phillips USA Physics of Music Notes 2006 Retrieved December 1 2006 from www phy mtu edu suits notefreqs html Pic Timer 0 Calculator 2006 Retrieved November 10 2006 from www best microcontroller projects com pic timer 0 html Polypropylene Specifications 2006 Retrieved December 10 2006 from http www boedeker com polyp_p htm Robson Company Inc 2006 Dinsmore Compass Robson Company Inc USA Rotary Encoder Image 2006 retrieved 15 December from www en wilkipedia org wiki Image Encoder Disc 283 11 29 5 STMicroelectronics 2006 L293D PUSH PULL 4 Channel Driver with Diodes STMicroelectronics USA 60 Texas Instruments 2006 232 Max232I Dual EIA 232
106. rpts une ete oe eds el poe ri tede eed 101 Grid code Excerpta eee eerte itera 105 HAE Motor Code BxCetpt Re Un estis 108 H S Shape Gode EXcerpt x een eee ete 111 H 6 Servo Code Excerpt iie ROC ee edet miei eerie ed 115 Interr pt Code 117 Sound Code Excerpt ine eere see teres 121 viii Table of Figures Figure 1 Brief Overview of Child 13 Figure 2 3 bit Gray Encoder Wheel Rotary Encoder 2006 16 Figure 3 Bridge simulation Turning one direction eese 22 Figure 4 Bridge simulation Changed 22 Figure 5 Simulated PWM Output scsi tom rrr RR etn EN Fete een 22 Figure 6 Transistor H Bridge Circuit The Complete BJT Circuit 2006 23 Figure 7 IR Transmission Angle ios 27 1 8 Ris r with s Lotes e a Ha MR E 33 Figure 9 Drive Assembly 225 eM 35 Figure 10 Assembled Robot with boards in situ 36 Figure 11 Picl6F87XA Pin out Diagram Microchip 20066 38 Figure 12 Picture of Mamiboard ian 38 Fig re 13 LDR LEY
107. s iu bU Gi eite tes ix Glossa y Of Termsz tue X Chapter 1 Project Introduction oe RE RUE RH 11 artt Rete ram 11 1 2 Research ODJeCtivess ues ie eee ene it ce e eet 11 1 3 Research with teacher and 12 1 4 Conclusions Chapter T 23 2 ns e eate RI re OR da 14 Chapter 2 Component 1 nennen 15 2 1 Position Sensor Selection eei dis 15 2 1 1 Slotted Encoding wheel sess 15 2 52 Gray Encoder wheel ase og ameet esee dde 16 2 1 3 Rotary Encoder Potentiometer 17 2 1 Stepper 18 2 1 5 Halleffect sensorS3 1 a ee t eet 18 2 2 Motor SELECTION a etit ba ert tei pre Hber 19 2 2 ls Stepper reete rete reae ete e t etre e teat eee 19 2 2 2 SEVO MOOT eee eere RO Ree Tee eet e bea eee 19 2 2 3 Small DC motor and gear assembly sess 20 2 3 Electronic Compass Selection 2 1 1 00 044 0 2 0000 20 2 3 1 Dinsmore Digital Sensor 1490 20 2 3 2 Dinsmore Analogue Sensor 1525 21 2 3 3 Dinsmore Analogue Sensor 1655 21 2 4 Motor circuitry 1 eere nennen eene enne 21 2 41
108. se of the output properties of the Dinsmore Compass The full port is read and the irrelevant bits are removed The port is read every 0 5 seconds The output of the compass is a 4 bit word N 1000 NE 1100 E 0100 SE 0110 5 0010 SW 0011 W 0001 NW 1001 50 This is made up of the logic 175 and 0 s that indicate the compass direction To find if the robot is heading in the right direction the code checks the current direction against a look up table with the above binary codes in it and takes note of the table number of the relevant binary code The required direction binary code sent from the computer 15 checked in the same table Its Table position is also noted Depending on the differences between these two values the robot will turn either left or right e g the robot is heading SW 0011 position 5 keeping in mind the tables first entry is counted as 0 and the new coordinate is E 0100 position 2 The difference is less then 4 table positions before the current bearing so the wheel turns right and the robot reverses until the new position is found If we were heading SW 0011 and wished to go N 1000 North is greater then 4 positions before in the table so the wheel turns left and the robot reverses until the correct heading is reached The Hall Effect Sensors are used to detect the distance travelled This 15 updated each step and is discussed in the Interrupt section The code is shown in Appendix H 2 5 4 3 Grid followi
109. ss y PicCompass CurrentY End If Skipthis False End Sub Private Sub CmdOption_Click Index As Integer provceses the buttons pushed Select Case Index Case 0 Exit FrmMain Show Unload Me Set FrmCompass Nothing Case 1 Program the pic FrmInterface Show DoMultiple Unload Me Set frmAxis Nothing End Select End Sub Private Sub Form Load add the captions set the position og the form and its contents set line and picturebox settings initialise variable ReDim XBack 10 ReDim YBack 10 ReDim CoOrd 10 1 CmdCompass 0 Caption N CmdCompass 0 FontBold True CmdCompass 1 Caption S CmdCompass 1 FontBold True CmdCompass 2 Caption W CmdCompass 2 FontBold True CmdCompass 3 Caption E CmdCompass 3 FontBold True CmdCompass 4 Caption NE CmdCompass 4 FontBold True CmdCompass 5 Caption SE CmdCompass 5 FontBold True CmdCompass 6 Caption SW CmdCompass 6 FontBold True CmdCompass 7 Caption NW CmdCompass 7 FontBold True 92 CmdCompass 8 Caption C CmdCompass 8 FontBold True PicCompass Width PicCompass Height PicCompass Left FrmCompass Width PicCompass Width 2 CompassFrm Left FrmCompass Width CompassFrm Width 2 PicCompass CurrentX PicCompass ScaleWidth 2 PicCompass CurrentY PicCompass ScaleHeight 2 x PicCompass CurrentX y PicCompass CurrentY LstDirection Height PicCompass Height PicCompass DrawMode 6 P
110. st CoOrd XX amp H9 b1001 NorthWest Case 8 Erase Button Steps back through the history and deletes the lines on each click by putting a background color line over the line removes the deleted point s from memory and the direction display stops the initial point being deleted PicCompass ForeColor amp HEOEOEO set the color to grey PicCompass Line x y XBack XX YBack XX get the last point 1 If XX 1 Then 1 go back to the start dont erase the PicCompass DrawMode 6 point on the screen PicCompass PSet x y PicCompass DrawMode 13 End If CoOrd XX delete the coordinate the variable x PicCompass CurrentX y PicCompass CurrentY Skipthis True LstDirection ListCount If F gt 0 Then LstDirection Removeltem F 1 delete the direction from the list End If PicCompass ForeColor amp H0 amp the color to black End Select Adds the points to the history draws the new line on the screen If Skipthis lt gt True Then XX 1 gt If XX Mod 10 0 Then make sure the array 15 always big enough ReDim Preserve XBack XX 10 ReDim Preserve YBack XX 10 ReDim Preserve CoOrd XX 10 XMax XX 10 End If End If 9 PicCompass Line x y PicCompass CurrentX PicCompass CurrentY draw the line XBack XX x store for history YBack XX y x PicCompass CurrentX store the current position for next pa
111. tell it which shape to draw The shapes and sizes are predefined 5 2 6 Remote control The remote control interface uses two methods of steering The appropriate buttons can be clicked with the mouse to send a command to the robot Otherwise the Key Press option has been set on the Remote control form so presses from the keyboard are trapped The w z a d g and s keys trigger the appropriate button event so the robot can be operated remotely The go button must be pushed to start the robot or restart after a stop The exit button automatically stops the Robot at the same time dx Remote SAX This area controls the robot directly either click the buttons or type the letters to control 5 bz 8 Click go to start or Ext restart after stop Figure 24 Remote control menu 47 5 3 Interesting Aspects of the Computer code 5 3 1 The Communication Port code Visual basic 6 has built in OCXs and DLLs that handle most of this interfacing These works fine on all Windows O Ss Pre XP or the NT series For the later versions a port interface like Inpout32 dll http www logix4u net inpout32 htm is required Logic4U the coder of this interface software was approached and rights were given to include this DLL with this software in any future incarnation As for the Visual Basic code Appendix F 3 the relevant comport is called it is turned on and the data is sent This interaction is very easy 5 3 2 Th
112. th meaning large wheels would be required to give the robot clearance This would involve more cost and could cause the robot to become or appear top heavy The manufacture of a suitable bracket to mount the unit in its final position was also a concern It would involve metal manufacture to build something substantial enough to counteract the torque of these units Unfortunately this meant more cost in the form of complicated construction that required specialised input These motors can also be quite costly though they can be sourced at second hand shop in the form of second hand computer Printers have one or two motors inside and can be stripped for salvage The issue with this source is consistency of product size and specifications with different manufacturers using different motors for their products Mounting was the main constraint on the use of stepper motors for this project with the height issue coming next 2 2 2 Servo motor Servomotors are commonly used in steering mechanisms or actuation applications They are very powerful and have good amounts of torque There is usually a range constraint on their rotation of around 180 Fortunately they can be modified so the actuator can do a full 360 revolution In this application they 19 could easily be used by for the locomotion in this project The use of servomotors in the design had the following implications a Cost The cheapest servo cost 20 This made it one of the
113. the built in Timers on the Picl6f877A still allow the generation of PWM By toggling a Pin on and off at the required rate the PWM is generated After experimentation the use of Timer0 was the easiest to do this with This is previously used for the servo function but by using the music functions after the other function has finished both functions are easily satisfied The output 15 then channelled to another pin Full code in Appendix H7 The built in Timer0 can measure time increments from 2us to 65 356ms Considering that 1000 Hz 0 001 seconds or 1 ms and the required note frequency range is 262 to 1175 Hz using this timer to create the musical notes was quite feasible Calculating the specifications for these times is quite a tedious calculation Considering the prescaler goes from 1 2 to 1 256 with dozens of variations of timings being able to be produced with the prescaler and TMRO setting To speed up the process a Timer calculator was found on the web http www best microcontroller projects com pic timer 0 htm This calculator allowed the values to be tested and experimented with easily One factor that came to light while using this calculator was the fact that the Times ran off at either end on a single Prescaler This meant that exact values for the Frequencies weren t possible for most of the range on a single Prescaler setting but close approximations that would be possible Exact values could possibly be found by moving the
114. the robot to make the centre lighter CheckL movf ADHF w subtract the high bits front from right movwf Temp subwf ADHL w STATUS Z higher bit is the same so check against left goto CheckAllLower BTFSC STATUS C one was bigger goto GoStr8 Straight was lower goto GoR Left was lower CheckAllLower movf ADLF w subtract the high bits front from right movwf Temp subwf ADLR w STATUS Z higher bit is the same so check against left goto CheckLAll BTFSC STATUS C one was bigger goto CheckLAIl front was lower same check as above sright was lower movf ADLR w subtract the high bits front from right movwf Temp subwf ADLL w BTFSC STATUS C one was bigger goto GoL Right was lower goto GoR Left was lower CheckLAIl movf ADLF w subtract the high bits front from right movwf Temp subwf ADLL w BTFSC STATUS C one was bigger goto GoStr8 Straight was lower goto GoR Left was lower 99 Store the LDR values so they can be processed GetNext FSR f goto LDR PutF Point to Next LDR continue to check while set in this mode movf ADValueH w Store the front value movwf ADHF movf ADValueL w movwf ADLF goto GetNext PutL Store the front value movf ADValueH w Store the front value movwf ADHL movf ADValueL w movwf ADLL goto GetNext PutR Store the front value movf ADValueH w Store the front value movwf ADHR movf ADValueL w movwf ADLR clrf i return movlw d 3 movwf
115. tmr0 interrupt enabled goto IntEnd DoMusic Toggles the Sound on and off so they become a musical note DoMusic movf NoteToggle w subwf 0x01 w skpnz goto NoteOn goto NoteOff 2 2 3 Turns DortD pin 0 on for on portion of note NoteOn bsf PORTD 0 turn the note on bsf NoteToggle 0 123 goto NoteStart 2 2 NoteOff Turns DortD pin 0 off for off portion of note NoteOff bcf PORTD 0 turn the note off bcf NoteToggle 0 NoteStart loads the note value to so the interrupt will fire again NoteStart movf Note w movwf TMRO goto IntEnd 124
116. tract 55 so equals relevant number subwf Note w goto GetNote 2 2 WorkNumber Finds the Hex equivalent of a number WorkNumber movlw 0x30 Subtract 48 so equals relevant number subwf Note w goto GetNote thanks to Myke Predko and Programming and customising PicMicro Microcntrollers for this gem of a code to stop the table from going scrub movwf Temp movlw HIGH TheSongs movwfPCLATH movf Temp w LOW TheSongs STATUS C incf movwfPCL TheSongs Also SPrach Zarathustra Intro Richard Strauss Starts 0 Blue Danube Johann Strauss Starts 015 Ode to Joy Ludwig van Beethoven Starts 0058 DT 145484F2D2D4D4L517191910191910171710151719191019191018181L7171819191 81716151516171718182L MusicalNotes lookup table for the notes tmr0 amounts MusicalNotes thanks to Myke Predko and Programming and customising PicMicro Microcntrollers for this gem of a code to stop the table going scrub movwf Temp movlw HIGH TheNotes movwfPCLATH 122 movf Temp w LOW TheNotes STATUS C incf PCLATH f movwf PCL TheNotes dt 0x00 Rest 0 dt 5 LowC 1 dt 20 Low D 2 dt 45 E3 dt 69 F4 dt 79 LowG 5 dt 99 6 dt 116 B 7 dt 132 8 dt 139 D 9 dt 152 E A dt 163 F B dt 168 G dt 178 HighA dt 187 High B E dt 195 High dt 198 High D G StopMusic As it says can stop the music call NoteOff bef INTCON
117. wheel The encoder wheel is commonly used for this style of application The principles behind its use are very simple Historically this style of sensing incorporates a wheel with slots cut at regular intervals around its circumference a light emitting diode often infrared and a matching sensor As the wheel turns while the robot is moving it causes the light beam to be interrupted The related circuitry converts this to a pulse that can be sent to the microcontroller This sort of encoding wheel is very often used in computer mouses the variety with a ball that contacts the mouse pad where accuracy and small movement detection are required The main drawback for this situation comes in the size of the encoder wheel itself Because of the size constraints underneath the robot this encoder wheel would have to be less than 20 mm diameter The simplest way to get a precision wheel of this size would have been to purchase a cheap mouse and use the wheels and circuitry from this to enact the system While this was considered two objections came against it a Cheap mice seem to be imported in lots and once they are all sold the next lot are of different design It is possible the changes in design may make them incompatible with the final robot design b The design of the encoder wheel incorporates a shaft that actually contacts the ball of the mouse This usually clips at either end to give the unit stability so the movement interaction
118. x02 btfsc STATUS Z call set PulseL movf ADPos w sublw 0x03 btfsc STATUS Z Clear TMRO interrupt Re initialise TMRO MAKE PINO pwm high for servo 18 this the front LDR is this the Left LDR Is this the right LDR 118 call PulseR bcf 0 set low again to finish pul goto IntEnd Tmrl INT bef PIRI TMRIIF Clear Timer Interrupt Flag call resetButton in case the button debounce is called decf TMRICount BCF PIRI TMRIIF Clear Timerl Interrupt Flag MOVLW d 133 TIMIH TMRIL gives 1 4 second MOVWF TMRIH overflow at 32 KHz MOVLW d 238 MOVWF TMRIL movlw 0x01 see if this 15 just a second count subwf SecBool w skpnz goto IntEnd decf NoteTime skpnz goto Load Next Note goto IntEnd PortBInt Processes the PortB interrupt reads in the pins recordes their values these values are checked against the next pass to make sure a pin isnt read twice in error if there is a change the pin 15 priocessed PORTBInt movf PORTB W movwf HoldPortB movlw b 10000000 check if Pin7 changes subwf LastPortB7 w this 18 emergency stop btfss STATUS Z call Service7 movlw b 00010000 check if Pin4 changes andwf HoldPortB w from last time INTB was fired subwf LastPortB4 w btfss STATUS Z call Service4 movlw b 00100000 check if Pin5 changes andwf HoldPortB w from last time INTB was fired subwf LastPortB5 w btfss STATUS Z 119 call

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