SpyMobile

1. SpyMobile Stanley Mlekodaj Pavel Shostak ECE 345 – Senior Design Spring 2003

2. Objective • Create a remote-controlled vehicle with long range capabilities that will be able to capture audio and video footage and relay it back to control center. ECE 345 – Senior Design Spring 2003

3. Key Components • Physical Car Implementation • Chassis, wheels, motors, etc. • Transmitter • Linx Transmitter, 8x3 Encoder, Parallel/Serial Encoder • Receiver • Linx Receiver, Serial/Parallel Decoder • Control Module • Motora HC12 Microcontroller, Motor Drivers • Wireless Camera • 2.4 GHz X10 Wireless Camera with audio/video ECE 345 – Senior Design Spring 2003

4. ECE 345 – Senior Design Spring 2003

5. Physical Car Implementation • Created from scratch to fit designobjectives: • Chassis – 10”x6” Aluminum • Wheels – 2.75” diameter neoprene • Motors – High power DC motors • Drive System • 6 V power supply, 2 - 4 AA packs • 2 Motors driving left and right side independently • Belt drive supported by 8 pulley system ECE 345 – Senior Design Spring 2003

6. Transmitter • Portable transmitter powered by 9V battery • Switches for selecting Left/Right, Forward (3 speeds) and Backward (3 speeds) • Digital 8-to-3 Encoder for switch input • Converts switch selection into bit sequence • Parallel-to-Serial Encoder • Converts individual bit sequences into serial data stream • Linx Transmitter HP-II (900MHz) RF Module • Transmits serial data stream wirelessly to the car ECE 345 – Senior Design Spring 2003

7. Transmitter Block Diagram Antenna 8x3 Encoder Parallel to Serial Encoder 900 MHz Linx Transmitter Control Switches ECE 345 – Senior Design Spring 2003

8. Receiver Block Diagram Antenna 900MHz Linx Receiver Serial to Parallel Decoder 68HC12 Microcontroller Pre-Amp Circuit ToMotors Motor Drivers ECE 345 – Senior Design Spring 2003

9. HC12 Microcontroller • Accepts the received four bit instruction • Additional valid transmission bit from decoder • Control code parses instruction and delivers appropriate signal to motors • PWM feature used to create variable speeds by varying signal duty cycle ECE 345 – Senior Design Spring 2003

10. Read Data Control Flowchart no Valid Data? Compute Reverse of Last Valid Instr. yes Decode instr. Left? yes 50% Speed Left mtr. bwd Right mtr. fwd no Right? yes 50% Speed Right mtr. bwd Left mtr. fwd no Backward? yes Decode speed, Set PWM Both motors backward no Forward? yes Decode speed, Set PWM Both motors forward no

11. Testing • Motors tested for rotation/minute and current draw under load conditions • Car tested for maneuverability • Several changes made to wheel and motor placement and pulley drive system • Control code tested for proper response • Motor drivers tested for sufficient current output ECE 345 – Senior Design Spring 2003

12. Variable Speed Control 50% Duty Cycle ECE 345 – Senior Design Spring 2003

13. 70% Duty Cycle ECE 345 – Senior Design Spring 2003

14. 90% Duty Cycle ECE 345 – Senior Design Spring 2003

15. Accomplishments • Car built according to original design considerations • User-friendly portable transmitter • Working control code with variable speed functionality • Additional response to lost transmission ECE 345 – Senior Design Spring 2003

16. Problems Encountered • Extremely sensitive link between transmitter and receiver modules • Broken link presented problems within control code • Attributed to control switches and faulty contacts in Linx modules • Problems with amplifying logic output signal to drive motors • Motor drivers used did not supply enough current to motors ECE 345 – Senior Design Spring 2003

17. Recommendations • Given more time, the following changes would have been made: • Use bigger motors to handle the weight • Have wheels as close to the center as possible to improve maneuverability • Use debounced switches for transmitter ECE 345 – Senior Design Spring 2003

18. Acknowledgements • We would like to thank: • Professor Swenson • Machine Shop • ECE 345 TA’s • ECE Department • Mabuchi Motor Company ECE 345 – Senior Design Spring 2003