2. A.G.I.L.E Autonomously Guided Intelligent Lawn Equipment Team Members: Brad Ramsey Derek Rodriguez Dane Wielgopolan Project Advisors: Dr. Joel Schipper Dr. James Irwin

3. Who wants to mow the lawn? Who wants to pay someone else to mow the lawn? Why Build It?

4. Project Goal Create a proof of concept autonomous lawnmower Mow the lawn while – Staying in a defined area – Avoiding obstacles – Efficient mowing

5. Key Components Compass Microcontroller Software Sensors Motors Batteries

6. Key Components Compass Microcontroller Software Sensors Motors Batteries

7. Platform Dimensions: Length: 12.5’’ Width: 18.5’’ Height: 7’’ Symmetrical Dual 12V lead acid batteries Dual Pittman DC motors Differential turning – Zero turning radius All electronics designed to work off of 12VDC

8. Perception Radio frequency (RF) dog fence detectors Ultrasonic sensors to locate objects

9. “Ears” Radio frequency circuits Sense by signal strength

10. RF Filter Flowchart 1) Single-Frequency Band Pass Filter 2) Gain stages 3) Rectifier 4) Unity Gain Op-Amp 5) ADC on Emac

11. RF Filter Design Frequency - 333 KHz Low frequency (LF) spectrum IC used is LM318D High Slew Rate and Gain Bandwidth Product Within desired noise floor

12. “Eyes” Ultrasonic sensors Projects sound wave Listens for echo Converts time to distance SRF05 – 3m range We only need 1m

13. Reading the Ultra-Sonics Software Counter Returns Value from 0-250 250 is approximately 1m

14. Obstacle Avoidance Ultrasonic sensors scan environment Distance thresholds are used in software Environment is stored in memory Proper action is taken

15. Obstacle Avoidance

16. Key Components Compass Microcontroller Software Sensors Motors Batteries

17. Navigation Digital compass Voltage regulator PWM signal Follows heading Precise 90 and 180 degree turns Difficult indoors }

18. Compass Tracking Error = (Heading – Desired heading) x Gain Error modifies PWM signals accordingly Example: Turn Left Error = 90 = (45-0)*2 LEFT MOTOR – ERROR & RIGHT MOTOR + ERROR

19. Motor Control Utilizes the EMAC’s onboard DAC 0V to 5V → 0% to 100% duty cycle H-Bridges control direction

20. Key Components Compass Microcontroller Software Sensors Motors Batteries

21. Intelligence Software uses sensors’ data Follow the border Cover the field twice Avoid static and dynamic obstacles

22. Basic Algorithm Uses dog fence as border Starts with border Ideal for square field More testing Minimal areas missed

23. Wall Following Ideal Signal Strength Error correction Containment All shapes

24. Wall Following When do I stop? Turn counter Switch modes

25. Double Cut Missed areas – Light blue/light green Up-Down pattern – Blue Left-Right pattern – Green

26. Software Execution time – 147mS – 160mS Human reaction time – 250mS

27. Safety Features Stay with in mowing area – Avoid unknown obstacles – Don’t cut neighbor’s yard Ultrasonic sensors – Don’t run over life forms – Don’t crash into walls Bump sensors – Last line of safety protection Kill switch – Manual cutoff

28. System Block Diagram

29. Completed Mower

30. Questions?

31. Ultrasonic Error Correction

32. Microcontroller Connections

33. Compass Read Function

34. Compass Read Code int readcompass() { unsigned int reading=0; while(compassPWM==1){} //if its already high, wait while(compassPWM==0){} //if its low, wait while(compassPWM==1) //if its high, start counting until it falls low, then return count { reading++; } reading = (reading/13)-10; //convert to value between 0 and 359 if(reading > 380){reading = comp_readingold;} //error checking ignore massive error if(reading > 359){reading = 359;} //error checking comp_readingold=reading; return(reading); //return(compass_lookup(reading));//lookup table }

35. Actions Truth Table

36. Maximum reaction time of 200ms Max Speed: 2 ft/s Distance until reaction 0.4 ft/s or 0.12 meters Distance to Stop