Autonomous Robot Merlin Perry Travis Shricker Ross Aten
Goal • Build an Autonomous robot that will navigate the R-4 parking lot using GPS tracking data.
GPS • The Global Position System uses a 3 segment system: Space, User, & Control segment. • Space – consists of 24 satellites circling the globe at 12000 miles above the earth • User – the GPS device and the user • Control – controls GPS satellites by tracking and sending data.
GPS • The GPS, in order to work properly, must be in contact with at least 4 of the 24 satellites at all time. • The GPS picks up two types of data almanac and ephemeris when these are known the location of all the satellites at all time is known.
GPS Data • The GPS gives out a lot of different data once every second but our group only focused on one line : $GPRMC – Recommended Minimum Specific GPS/Transit Data (RMC) • UTC - Coordinated Universal Time • This one line provided all the necessary data needed to perform the given goal
GPS altering • Since our group only focused on the GPRMC line we decided that we would program the GPS to only give out that one line once a second
GPS Simulation • A useful tool was the GPS simulation that could be used to test the car without physically having to go outside.
Transceiver • One pivotal step was making sure that the transceiver and the MSP where communicating correctly and sending valid data to each other.
Voltage Regulator • Used a MAX640 & MAX639 to output 3.3volts for the MSP430 & 5volts for the servo. • The MAX regulators were used because they are high efficiency switching regulators.
Servo • Used PWM to control the servo • When the servo was mounted it was a little lose causing the wheels to pivot a little. • Steering wasn’t as tight as it could have been.
H-Bridge • Used the H-bridge to control the motor. • Sent a PWM to the forward plug and when signal went low the motor would go.
Problems • Didn’t get the program running in time. Ran into a lot of algorithmic program problems. • Ran out of programming time. • Motor would either go to slow or to fast for correct steering. • Never had the right ratio between turning and speed.
Reference • http://www.colorado.edu/geography/gcraft/notes/gps/gps_f.html • http://www.garmin.com/aboutGPS/manual.html • http://www.hvwtech.com/pages/ • http://www.fatlion.com/sailplanes/servos.html • http://www.maxim-ic.com/