1. Control Some Material taken from RobotSubsumption.pdf

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

3. Controlling Robot Movement Based on QTI (or Photo-Resistor) Readings ' -----[ Constants ]--------------------------------------- LeftDark CON 108 RightDark CON 114 LeftWhite CON 20 RightWhite CON 22 ' Average light sensor value LeftThreshold CON LeftWhite + LeftDark / 2 RightThreshold CON RightWhite + RightDark / 2 ' -----[ Variables ]---------------------------------------- timeLeft VAR Word timeRight VAR Word ' -----[ Main Routine ]------------------------------------ DO GOSUB Test_Light GOSUB Navigate LOOP

4. Code ' -----[ Subroutine - Test_Light ]-------------- Test_Light: HIGH 3 ' activate Left QTI sensor HIGH 2 PAUSE 1 RCTIME 2, 1, timeLeft LOW 3 ‘ deactivate sensor HIGH 7 ' activate right QTI sensor HIGH 6 PAUSE 1 RCTIME 6, 1, timeRight LOW 7 ‘ deactivate sensor

5. Code ' -----[ Subroutine - Navigate to avoid light ]------------- Navigate: IF (timeLeft < LeftThreshold) AND (timeRight < RightThreshold) THEN PULSOUT 13, 650 ‘ go backwards PULSOUT 12, 850 ELSEIF (timeLeft < LeftThreshold) THEN PULSOUT 13, 800 ‘ go right PULSOUT 12, 600 ELSEIF (timeRight < RightThreshold) THEN PULSOUT 13, 600 ‘ go left PULSOUT 12, 800 ELSE PULSOUT 13, 850 ‘ go forwards 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 Measurement ' {$STAMP BS2} ' {$PBASIC 2.5} ' -----[ Pins ]----------------------------------- Trigger PIN 0 Echo PIN 1 ' -----[ Variables ]----------------------------- samples VAR Nib ' loop counter pWidth VAR Word ' pulse width sonic sensor rawDist VAR Word ' filtered distance cm VAR Word inches VAR Word irDetectLeft VAR Bit irDetectRight VAR Bit pulseCount VAR Byte ' -----[ Constants ]----------------------------------- Trig10 CON 5 ' trigger pulse = 10 uS ToCm CON 30 ' conversion factor to cm

8. Code ' -----[ Main Routine ]----------------------------------- DO GOSUB Read_IR GOSUB Read_Sonar IF (sonarForward = 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 = IN3 RETURN Read_Sonar: rawDist = 0 FOR samples = 1 TO 5 ' take five samples PULSOUT Trigger, Trig10 ' 10 uS trigger pulse PULSIN Echo, 1, pWidth ' measure pulse rawDist = rawDist + (pWidth / 5) PAUSE 10 NEXT IF ( ((rawDist / ToCm) */ $03EF) ) < 36 THEN sonarForward = 0 ELSE sonarForward = 1 ENDIF RETURN

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

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

12. Finite State Machine (FSM) Representation Read IR & Sonar Go forward turn left turn right go forward Obj forward Obj right Obj left No Obj

13. How to Put It Together? Read IR & sonar Go 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  Never detect opponent  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

16. FSM read IR & sonar 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. Program High-Level Outline 1. Declare pin assignments, constants and variables 2. Initialize thresholds 3. Wait the required start delay 4. Read boundary line sensors and move accordingly 5. If the boundary line is not detected, read proximity sensors and move accordingly 6. Repeat steps 4 and 5 until completion

19. Main Loop Do GOSUB Read_Line_Sensors IF (lightLeft < leftThresh) AND (lightRight < rightThresh) THEN GOSUB About_Face ' boundary ahead ELSEIF (lightLeft < leftThresh) THEN GOSUB Spin_Right ' boundary to left ELSEIF (lightRight < rightThresh) THEN GOSUB Spin_Left ' boundary to right ELSE PULSOUT LMotor, LFwdFast PULSOUT RMotor, RFwdFast GOSUB Search_For_Opponent ENDIF Loop

20. Possible Enhancements  Optimize the position of the sensors  Optimize your mechanical design for fighting Consider using lego components including motors Design against being pushed out of the ring  Optimize the code to maximize bot performance Evaluate tradeoffs in movement choices and sensor reading  Optimize the programming constructs that you use to increase processing speed BRANCH value, (Case_0, Case_1, Case_2) LOOKUP Index, (Value0, Value1,...ValueN), Variable LOOKDOWN Target, {ComparisonOp} [Value0, Value1,...ValueN], Variable