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Prepared by: Jeremy Hubbard Dept. of Electrical and Computer Engineering Utah State University E: j.l.hubbard@aggiemail.usu.edu; F: (435)797-3054 (ECE Dept.). ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Global Positioning System. 3/7/2008.
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Prepared by: Jeremy Hubbard Dept. of Electrical and Computer Engineering Utah State University E: j.l.hubbard@aggiemail.usu.edu; F: (435)797-3054 (ECE Dept.) ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Global Positioning System 3/7/2008
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Outline • Reference list • To probe further • Major applications • Basic working principle illustrated • A sample configuration • Major specifications • Limitations
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Reference list • http://www.gps.gov/ • http://www.colorado.edu/geography/gcraft/notes/gps/gps_f.html • http://aprs.gids.nl/nmea/
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators To explore further (survival pointers of web references etc) • http://en.wikipedia.org/wiki/Global_Positioning_System
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Major applications • Outdoor position sensing • UAV position • Car Navigation • Backwoods Navigation • Timing • Precise worldwide timing • Surveying • etc...
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Basic working principle illustrated • Constellation of satellites constantly sends out extremely accurate time information along with orbital information. • Using triangulation based on the doppler effect the precise position of almost any place on earth can be calculated. http://en.wikipedia.org/wiki/File:ConstellationGPS.gif
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Basic working principle • The satellites transmit data in frames and subframes for the GPS receivers to decode http://www.colorado.edu/geography/gcraft/notes/gps/gps_f.html
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators A typical sample configuration • The data is transmitted serially to a microcontroller • Microcontroller parses data to get position • http://phy5ics.com/blog/wp-content/uploads/2008/11/gps_bt_schematic_rev1.jpg
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators A typical sample configuration • Data from GPS is commonly output in NMEA format • For information on decoding NMEA sentences see: http://aprs.gids.nl/nmea/ • Typical data included in NMEA sentences includes: signal quality, satellites in view, quality of position lock, latitude and longitude, ground speed, altitude, heading, time, and much other data.
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Major specifications • Number of Channels (12-50) • Time to fix (seconds): • Hot start: 8 • Warm start: 38 • Cold start: 42 • Output Protocol (NMEA or proprietary) • Antenna Gain • Receiver Sensitivity
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Major Specifications (cont.) • Supply Voltage • Supply Current • Accuracy (0.001 m to 3.3+m) • Augmentations (WAAS, DGPS, EGNOS, MSAS) • Output type: • SPI • UART
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Limitations • Accuracy is not high enough for many precision tasks • Update frequency may be to slow for many applications • Not always suitable indoors
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators GPS Accuracy • Low-cost, single-receiver SPS projects (100 meter accuracy) • Medium-cost, differential SPS code Positioning (1-10 meter accuracy) • High-cost, single-receiver PPS projects (20 meter accuracy) • High-cost, differential carrier phase surveys (1 mm to 1 cm accuracy) • Prices range from about $50 to $50000
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators How to choose • Types of modules available: • GPS module • Antenna is onboard, easiest to interface with, typically a UART on a microcontroller is suitable • OEM module • Not mounted on a PCB, most customizable, but PCB may need to be designed for RF depending on the module and antenna chosen, additional components may be required.
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators How to choose (cont.) • Update frequency • Most modules update between 1Hz and 5Hz • System power • Typical modules run on 1.8, 3.3, or 5 V • Current supply ranges from 20mA to 100mA • Required accuracy, major determination of cost • TTFF • Antenna gain high enough for the application
ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Where to Buy • www.sparkfun.com • www.digikey.com • www.mouser.com • http://www.usglobalsat.com/c-43-engine-boards-modules.aspx • Various other online retailers