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School of Electrical and Computer Engineering. Wireless Telemetry System for Solar Vehicle. Scott Cowan Elliot Hernandez Tung Le March 14, 2011. Project Overview. Source: http://www.ece.gatech.edu/academic/courses/ece4007/10fall/ECE4007L01/ws1/files/sjt_final_presentation.ppt. - PowerPoint PPT Presentation
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Wireless Telemetry System for Solar Vehicle
Scott CowanElliot Hernandez
Tung Le
March 14, 2011
School of Electrical and Computer Engineering
Project OverviewWireless 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
Chase Car
Laptop
Solar Car
SBC
USB
Current
Speed
Temperature
Voltage
RS-485/RS-232
GPS
Battery Mgmt.Motor Ctrl.
MPPTHMI
Data Storage
USB
USB
SPIDIO
Transmitter
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
• 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.
MPPTHMI
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 Unit Price Extended CostCurrent sensors 6 ea $10.00 $60.00
Signal wiring 1 lot $100.00 $100.00Misc connectors 1 lot $100.00 $100.00
Total $260.00
Questions?