Homing Tank with Obstacle Avoidance (HToA)

1. Homing Tank with Obstacle Avoidance (HToA) Seth “The Assembler” Hill Jason “The Electrician” Brue

2. Project Objectives • Tank will move towards and find an infrared emitting beacon • The tank will be positioned anywhere within the emitting radius of the beacon • Once underway, the tank will stop periodically to adjust steering • The tank will stop once crossing a reflective tape circle around the emitter

3. Project Objectives (cont.) • Tank will avoid obstacles • If a obstacle is perceived, the tank will stop immediately and move around it • Once the obstacle has been successfully navigated, the tank will continue towards the infrared beacon

4. Project Specifications • Beacon • Will transmit infrared signal equally within its 360º radius • Vehicle must be placed within an 11 meter radius of the beacon • Obstacles • Must be shorter than infrared emitters/receiver • Must not be concave • Must be as high or higher than the ultrasonic sensor • Cannot be dynamically placed once vehicle homing has begun

5. Project Specifications (cont.) • Tank • Must have a turning radius of close to 0 • Must be large enough to hold all on-board components • HC12 • Servomotor • Ultrasonic sensor • IR receiver • Opto-reflector • Power supplies

6. Project Specifications (cont.) • Miscellaneous • There shall be no other infrared emitting devices within range of the receiver • There shall be no other ultrasonic emitting devices within range of the vehicle • There shall be no reflective surfaces, other than the tape, in the path of the vehicle. • There shall be a 2 foot radius between the reflective tape ring and the infrared beacon

7. Done Avoid / Search Reflective tape sensed IrDA received strength +5 Volts Motor 1 On Motor 2 On Debugging LEDs On/Off Switch Start Switch Debug Switch Project Specifications (cont.) • User interface • Input • Output

8. Random Analytical Facts • Height of infrared emitters: 70cm • Radius between infrared beacon and reflective tape: .5m • Tank footprint: 410mm Length 150mm Width • Turning radius: 13.29mm • Ultrasonic sensing range > 13.29mm + stopping distance of tank motors (tbd) • Lost productivity due to spam per employee per year: $874

9. Vehicle Control Algorithm Background loop: Output status to LEDs Goto Background loop Timer interrupt: Stop vehicle Sense beacon Adjust steering accordingly Move “forward” Obstacle interrupt: Stop vehicle If obstacle bit = ‘0’ then Rotate vehicle 90 clockwise Rotate ultrasonic sensor 90 counterclockwise Set obstacle bit = ‘1’ Endif Move forward No Obstacle Interrupt: If obstacle bit = ‘1’ then Stop vehicle Rotate vehicle 90 counterclockwise Rotate ultrasonic sensor 90 clockwise Move “forward” Endif

10. Seth HC12 assembly coding Ultrasonic sensor testing and integration Reflective sensor testing and integration Jason Beacon design and construction Beacon testing Tank motor testing and integration with H-Bridge circuit Servomotor testing and integration Division of Work • Both • System testing • Paperwork • Everything!

11. HC12 Port A Port B Port T Port P Port A/D Switches LED’s Photo Reflector Servo motor IR Receiver H Bridge US Drive Circuit DC Motor1 DC Motor 2 Ultrasonic Sensor Work Completed – System Block Design

12. Work Completed – Infrared Beacon

13. Work Completed – Infrared Beacon (cont.) • Timer must produce 38 KHz square wave with 50% duty cycle for infrared emitters • Each infrared emitter requires 60 mA of current for proper operation

14. Work To Be Completed (uh….) • Parts acquisition • Tank body has been chosen but has yet to arrive • Ultrasonic sensor has been rethought due to price constraints • Construction • Integration of all components with tank body • Coding • Everything • Testing • Beacon range and signal strength consistency • Servomotor • Ultrasound sensor • Opto-reflector • H-Bridge and Tank motors

15. Test Plan • Test individual components once they arrive for output voltage and current range • Integrate individual components and circuits together and insure proper operation • Integrate HC12 with all other components and write basic subroutines to ensure that microcontroller is interpreting inputs correctly • Implement controller algorithm as described previously

16. Test Plan – Controller Algorithm • Write assembly incrementally with each new section observing and reacting to new input(s) • Implement interfaces with: • tank motors • Implement interface with opto-reflector • Implement interface with servomotor • Implement interface with infrared detector • Implement interface with ultrasonic sensor

17. Test Plan – Final Stage • Once tank “appears to” be behaving “correctly” • Put tank in many different situations to ensure robustness of reaction • Distance from emitter • Number of obstacles • Placement of obstacles • Types of obstacles • Orientation of obstacles • Beginning orientation of tank • And anything else we can think of! • Any suggestions?

18. Power Consumption - Beacon • Power supplied – 18 Wh through 4 D-cell batteries • Therefore, one can expect to run the beacon continuously for 15 hours before a change of batteries is needed

19. Power Consumption - Tank • Until tank arrives, power requirements for DC motors are unknown • However, they will add a significant power requirement • Tank will be powered by a rechargeable 7.2V battery pack • Ultrasonic sensor has been rethought, and thus its power requirements are unknown • Although a major power requirement, it will be powered separately from the rest of the tank to ensure proper operation

20. System Cost

21. Safety Concerns • Some high powered devices onboard system could present shock hazard • During demo, moving tank may create traffic congestion and possible pedestrian accident within the halls of the computer engineering building • Falling infrared beacon may injure feet (please wear steel-shoed boots on demo day)