1. Mini Tankbot Homing Vehicle with Obstacle Avoidance By Jamie Mitch

2. The Idea Build a small mobile robot on treads (a tank) Add some sensors Get it to find a beacon within a room Keep it from running into things

3. Basic Logic Look for Beacon If not found, wander Head towards Beacon If obstacles detected, avoid Periodically check location of beacon and adjust direction Find Beacon

4. The Parts The robot kit Tankbot from BudgetRobotics.com  High-power Tamiya Twin Motor gearbox kit  Tamiya rubber tank tread kit (treads, sprockets, axles)  Precision pre-drilled and pre-cut plastic base -- includes second deck for micro controller or other electronics (hah.)

5. Assembled Mini Tankbot

6. The Parts (2) Motorola HCS12 micro processor 76 configurable I/O lines 8 channel, 16-bit enhanced capture timer 256K Flash 12K RAM 4K EEPROM

7. The Parts (3) Sensors SHARP GP2D15 Detector Package  Infrared ranger which will detect an obstacle within approx. 24 cm  Returns a logic 1 if detected, 0 if not detected Optek OPB745 Reflective Object Sensor  Detects a reflective object within its field of view  Range is approximately 3.8 mm

8. The Parts (4) A quadruple half H driver chip Allowed logic output from the processor to drive the two DC motors

9. The Parts (5) PNA4612M IR Detectors Can have a range of 11m or more Carrier frequency is 38kHz Will be mounted on the Tankbot LN64PA IR Emitters Angle range of approximately 45° Will be mounted on the Beacon

10. Obstacle Avoidance There will be 5 IR rangers on the tankbot 3 in the front to detect obstacles 2 in the rear to aid in determining if the obstacle has been successfully avoided The sensors will stop the tankbot approx. 9” from an obstacle, leaving plenty of room for maneuvering

11. Obstacle Avoidance (2) Ideally obstacles will be box shaped The logic If the model finds an obstacle, it will run a recipe to avoid it The processor will keep track of how far off course the avoidance recipe puts the tank, and will compensate after the obstacle is no longer a danger Problems with Logic What about walls?

12. The Tankbot

13. The Beacon The beacon will be a freestanding tube Will house the IR emitters Will contain the circuitry required to run the emitters, including one or more 555 timer chips Will be surrounded by reflective tape, to allow the model’s optoisolator to determine if the beacon has been found Will *not* be connected to a microprocessor

14. The Beacon (2)

15. User Interface Operations & sub-modesControllerIndicatorDescription ON/OFFSwitch (on/off) Red LED is on when Power is received Simply turns the power to the vehicle and controller board on and off -Switch (on/off) Green LED is litThe vehicle will find its beacon, and move toward it ResetButton-Acts like a Panic Button: resets the system to Standby Seeking-Blue LED is flashing The vehicle is currently seeking the signal from its beacon Found-Blue LED is litThe vehicle has found its signal, and is following it to the source Collision Detected-Orange LED is litThe vehicle has detected a collision, and is avoiding it. The LED will go off after the collision is no longer a problem

16. User Interface (2) The interface display and described is a simplified version that can be expanded if time allows

17. Cost Estimates

18. The Problems/Obstacles Accurately designing the IR emitter circuit to create as close to 38kHz as possible Running into obstacles at an angle Soldering Working alone Batteries, Batteries, Batteries