Wireless Telemetry System for Solar Vehicle

1. School of Electrical and Computer Engineering Wireless Telemetry System for Solar Vehicle Scott Cowan Elliot Hernandez Tung Le March 14, 2011

2. Project Overview Source: http://www.ece.gatech.edu/academic/courses/ece4007/10fall/ECE4007L01/ws1/files/sjt_final_presentation.ppt

3. Prior Work from Fall 2010 • GPS receiver • Wi-Fi link • Data storage • Data acquisition • Voltage • Current • Temperature • Speed

4. Shortcomings of Fall 2010 Design • Current sensors • Low sensitivity • Unipolar sensing • Speed sensor • Fragile design • Interface board • Proto-board

5. Transition Problems • Programming • Serial Peripheral Interface (SPI) bus not working • Hardware dismantled • All sensors lost • Parts list incomplete • Part numbers missing

6. Spring 2011 Remedies • Current sensors • Lower range = higher sensitivity • Bipolar = bidirectional sensing • Speed sensor • Industrial sensor = robustness • Interface board • Printed circuit board (PCB) = permanence

7. Additional Features • Take advantage of SPI bus • Enclose PCB and SBC for protection • Read data from other subsystems on the RS-485 network

8. Current Status • Completed tasks • Preliminary schematic design • Component selection • Linux driver installation • Cross-compiler setup • Present tasks • Finalizing schematic and PCB designs • Soldering components • Coding program • Auto-sync • Transmit data

9. Design Overview Solar Car Current Transmitter Data Storage Chase Car Speed USB USB SBC Temperature SPI DIO Laptop RS-485/RS-232 USB Voltage Battery Mgmt. Motor Ctrl. MPPT HMI GPS

10. Current Measurement • Bi-polar Hall-effect sensor • Sensing range: ± 140 A • Maximum cable size: 1/2″ OD • 10 available inputs

11. Speed Measurement • Industrial Hall-effect sensor • Senses magnet attached to wheel • Sends pulse to SBC • Computes Δt between pulses Wheel

12. Temperature Measurement • Diode-connected transistor • Two available inputs for remote sensors • On-chip ADC • Accuracy of ±1 degree C

13. Voltage Measurement • Simple voltage divider network • Total of six 0-5 Vdc inputs • Three remote signal conditioners for voltages up to 120 Vdc

14. Interface Board • Custom PCB • Interconnection between Inputs/Outputs (I/O) and SBC • Signal buffering • Analog to Digital conversions

15. Single Board Computer • TS-7250 • Heart of telemetry system • Linux operating system • C language programming

16. Vehicle Location • GlobalSat BU-353 GPS receiver • NMEA 0183 protocol • Waterproof • Five foot USB cable

17. Data from Other Subsystems • Other subsystems communicate on RS-485 network • Telemetry “listens” through RS-485 to RS-232 converter • Relevant data captured and stored • Requested data sent to HMI Battery Mgmt. Motor Ctrl. MPPT HMI

18. Data Storage • 2GB USB flash drive • FAT16 file system • One record set per second • CSV file format

19. Data Transmission to Chase Car • ASUS WL-167g Wi-Fi transmitter • IEEE 802.11g standard • Supported by SBC drivers • Range of up to 150 m

20. Enclosure • Lightweight ABS plastic • Approximately 7 x 8 x 2.5 inches (W x L x H) • IP 54 rating

21. General Challenges • Slow delivery of parts has delayed testing • Current sensors • QSOP to DIP adapters • Identification of major components has delayed SBC programming • TS-7250 SBC • 2 GB USB memory stick

22. Interface Board Challenges • DesignSpark learning curve • Design and Library Creation tutorials helpful • Printed Circuit Board size limit • ECE machine limited to 7 x 8 inch PCBs • Component specification • Connector selection

23. Programming Challenges • TS-7250 SBC learning curve • Tyler Mann has assisted • Linux compatible drivers • GPS, Wi-Fi, and memory devices • Serial Peripheral Interface (SPI) Bus • Needs to work before PCB design is finalized

24. Future Testing • Speed sensor • Current sensors • Temperature sensors • Voltage signal conditioners • SPI bus • RS-485 to RS-232 converter • Communication to HMI

25. Project Schedule

26. Future Costs for Solar Jackets

27. Questions?