Transcript PPT
School of Electrical and Computer Engineering Wireless Telemetry System for Solar Vehicle Scott Cowan Elliot Hernandez Tung Le March 14, 2011 Project Overview Wireless Data from the Solar Car to the Chase Car Source: http://www.ece.gatech.edu/academic/courses/ece4007/10fall/ECE4007L01/ws1/files/sjt_final_presentation.ppt Prior Work from Fall 2010 • • • • GPS receiver Wi-Fi link Data storage Data acquisition – Voltage – Current – Temperature – Speed Shortcomings of Fall 2010 Design • Current sensors – Low sensitivity – Unipolar sensing • Speed sensor – Fragile design • Interface board – Proto-board Transition Problems • Programming – Serial Peripheral Interface (SPI) bus not working • Hardware dismantled – All sensors lost • Parts list incomplete – Part numbers missing Spring 2011 Remedies • Current sensors – Lower range = higher sensitivity – Bipolar = bidirectional sensing • Speed sensor – Industrial sensor = robustness • Interface board – Printed circuit board (PCB) = permanence Additional Features • Take advantage of SPI bus • Enclose PCB and SBC for protection • Read data from other subsystems on the RS-485 network 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 Design Overview Solar Car Chase Car Transmitter Data Storage USB USB Current Speed SBC SPI DIO Temperature Laptop USB GPS RS-485/RS-232 Battery Mgmt. Motor Ctrl. MPPT HMI Voltage Current Measurement • Bi-polar Hall-effect sensor – Sensing range: ± 140 A – Maximum cable size: 1/2″ OD – 10 available inputs Speed Measurement • Industrial Hall-effect sensor – Senses magnet attached to wheel – Sends pulse to SBC – Computes Δt between pulses Wheel Temperature Measurement • Diode-connected transistor – Two available inputs for remote sensors – On-chip ADC – Accuracy of ±1 degree C Voltage Measurement • Simple voltage divider network – Total of six 0-5 Vdc inputs – Three remote signal conditioners for voltages up to 120 Vdc Interface Board • Custom PCB – Interconnection between Inputs/Outputs (I/O) and SBC – Signal buffering – Analog to Digital conversions Single Board Computer • TS-7250 – Heart of telemetry system – Linux operating system – C language programming Vehicle Location • GlobalSat BU-353 GPS receiver – NMEA 0183 protocol – Waterproof – Five foot USB cable Data from Other Subsystems Battery Mgmt. Motor Ctrl. MPPT HMI • 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 Data Storage • 2GB USB flash drive – FAT16 file system – One record set per second – CSV file format 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 Enclosure • Lightweight ABS plastic – Approximately 7 x 8 x 2.5 inches (W x L x H) – IP 54 rating 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 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 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 Future Testing • • • • • • • Speed sensor Current sensors Temperature sensors Voltage signal conditioners SPI bus RS-485 to RS-232 converter Communication to HMI Project Schedule March 23, 2011 SBC sensing all sensors March 30, 2011 Wi-Fi transmission of data April 6, 2011 Complete printed circuit board April 13, 2011 Display data on remote laptop April 20, 2011 Final demonstration Future Costs for Solar Jackets Description Quantity UOI Current sensors 6 ea Signal wiring 1 lot Misc connectors 1 lot Unit Price Extended Cost $10.00 $60.00 $100.00 $100.00 $100.00 $100.00 Total $260.00 Questions?