1. Control Material taken from RobotSubsumption.pdf and SumoBot : Mini-Sumo Robotics

2. Remember Where Are We Going? Sumo-Bot competitions

3. Controlling Robot Movement Based on Photo-Resistor Readings ' -----[ Constants ]--------------------------------------- LeftDark CON 108 RightDark CON 114 LeftWhite CON 20 RightWhite CON 22 ' Average Scale factor LeftThreshold CON LeftWhite + LeftDark / 2 RightThreshold CON RightWhite + RightDark / 2 ' -----[ Variables ]---------------------------------------- timeLeft VAR Word timeRight VAR Word ' -----[ Main Routine ]------------------------------------ DO GOSUB Test_Photoresistors GOSUB Navigate LOOP

4. Code ' -----[ Subroutine - Test_Photoresistors ]-------------- Test_Photoresistors: HIGH 6 ' Left RC time measurement. PAUSE 3 RCTIME 6,1,timeLeft HIGH 3 ' Right RC time measurement. PAUSE 3 RCTIME 3,1,timeRight RETURN

5. Code ' -----[ Subroutine - Navigate ]-------------------------- Navigate: IF (timeLeft < LeftThreshold) AND (timeRight < RightThreshold) THEN PULSOUT 13, 650 PULSOUT 12, 850 ELSEIF (timeLeft < LeftThreshold) THEN PULSOUT 13, 800 PULSOUT 12, 600 ELSEIF (timeRight < RightThreshold) THEN PULSOUT 13, 600 PULSOUT 12, 800 ELSE PULSOUT 13, 850 PULSOUT 12, 650 ENDIF PAUSE 20 RETURN

6. Finite State Machine (FSM) Representation Read photo- resistors backup turn right turn left go forward both low right low left low both high

7. Controlling Robot Movement Based on Proximity ' {$STAMP BS2} ' {$PBASIC 2.5} ' -----[ Variables ]----------------------------------- irDetectLeft VAR Bit irDetectRight VAR Bit pulseCount VAR Byte

8. Code ' -----[ Main Routine ]----------------------------------- DO GOSUB Read_IR IF (irDetectLeft = 0) AND (irDetectRight = 0) THEN GOSUB Forward_Pulse ELSEIF (irDetectLeft = 0) THEN GOSUB Turn_Left ELSEIF (irDetectRight = 0) THEN GOSUB Turn_Right ELSE GOSUB Forward_Pulse ENDIF LOOP

9. Code ' -----[ Subroutines ]------------------------------------- Read_IR: FREQOUT 8, 1, 38500 irDetectLeft = IN9 FREQOUT 2, 1, 38500 irDetectRight = IN0

10. Code ' -----[ Subroutines ]-------------------------------------- Forward_Pulse: PULSOUT 13, 850 PULSOUT 12, 650 PAUSE 20 RETURN Turn_Left: PULSOUT 13, 650 PULSOUT 12, 650 PAUSE 20 RETURN

11. Code ' -----[ Subroutines ]-------------------------------------- Turn_Right: PULSOUT 13, 850 PULSOUT 12, 850 PAUSE 20 RETURN Back_Up: PULSOUT 13, 650 PULSOUT 12, 850 PAUSE 20 RETURN

12. Finite State Machine (FSM) Representation Read IRGo forward turn left turn right go forward Obj forward Obj right Obj left No Obj

13. How to Put It Together? Read IRGo forward turn left turn right go forward Obj forward Obj right Obj left No Obj Read photo- resistors backup turn right turn left go forward both low right low left low both high

14. Possible Problems  Jerky or halting movement  Chase object over boundary  More?

15. Possible Solution o Subsumption Architecture A programming process by which one behavior subsumes, or over-rides another based on an explicit priority that we have defined. First described by Dr. Rodney Brooks in "A robust layered control system for a mobile robot,” IEEE Journal of Robotics and Automation., RA-2, April, 14-23, 1986. o FSM with exit conditions o Optimize PBasic control commands

16. FSM read IR and set nextState variable read Photoresistors and set nextState variable check nextState variable and branch Go forward Go backwards turn teft turn right

17. Alternative FSM read Photoresistors and set nextState variable check nextState variable and branch Read IR Go forward turn left turn right go forward backup turn right turn left go forward

18. New PBasic Control Commands BRANCH value, (Case_0, Case_1, Case_2) is equivalent to: Test_Value: IF (value = 0) THEN Case_0 ' value = 0: go to label "Case_0" IF (value = 1) THEN Case_1 ' value = 1: go to label "Case_1" IF (value = 2) THEN Case_2 ' value = 2: go to label "Case_2"

19. New PBasic Control Commands LOOKUP Index, (Value0, Value1,...ValueN), Variable Find the value at location Index and store it in Variable. If Index exceeds the highest index value of the items in the list, Variable is left unaffected. LOOKDOWN Target, {ComparisonOp} [Value0, Value1,...ValueN], Variable Compare Target value to a list of values and store the index number of the first value that matches into Variable. If no value in the list matches, Variable is left unaffected. The optional ComparisonOp is used as criteria for the match; the default criteria is "equal to."

20. The Implementation lineBits VAR Nib lineLeft VAR lineBits.Bit1 lineRight VAR lineBits.Bit0 Main: GOSUB Read_Line_Sensors BRANCH lineBits, [Search_For_Opponent, Spin_Left, Spin_Right, About_Face] Read_Line_Sensors: HIGH LLineSnsIn HIGH RLineSnsIn PAUSE 10 RCTIME LLineSnsIn, 1, leftSense RCTIME RLineSnsIn, 1, rightSense ' convert readings to bits lineBits = %00 LOOKDOWN leftSense, >=[blackThresh, 0], lineLeft LOOKDOWN rightSense, >=[blackThresh, 0], lineRight RETURN

21. A Bit More Complicated Search_For_Opponent: GOSUB Read_IR_Sensors ' If opponent is not in view, scan last known direction. Turn toward ' opponent if seen by one "eye" -- if both, lunge forward BRANCH irBits, [Scan, Follow_Right, Follow_Left, Lunge] Scan: BRANCH lastIR, [Move_Fwd, Scan_Right, Scan_Left] Lunge: ' locked on -- go get him! FOR pulses = 1 TO 15 PULSOUT LMotor, LFwdFast PULSOUT RMotor, RFwdFast GOSUB Read_Line_Sensors IF (lineBits = %11) THEN Match_Over ' in sight and we're on the line NEXT GOTO Main