Quote:
Originally Posted by ekapalka
Believe it or not, there is actually a "typical" way to do this. It's called field-centric control, and is in fact so popular that it is included in the with the developing software (C++, Java and LabView, I think...) as an alternative to the more common robot-centric control. The only sensor needed is a gyro. Magnetometers haven't proven particularly successful for teams to use in competitions due to their high sensitivity (high enough to detect the earth's magnetic field -> high enough to detect the electronics on other teams robots). I'm not entirely certain how you would incorporate the accelerometer if you were going to use one... What language are you using?
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ekapalka is correct on which sensor is most commonly used successfully for field-centric control.
Most gryos actually sense for angular velocity while we are interested in the value for angular position. The code that retrieves the value for us performs the integration that turns the angular velocity reading into the position that we are concerned about. This matters because it is a source of drift in the gyro's angular position reading. It is important to reset the gyro's position value to 0 at the start of autonomous so that any drift that occurs while the robot is sitting on the field or between sitting on the cart and in its starting position on the field can be cancelled out. When we used field centric control in 2010, we also had a button for resetting the gyro in teleop so that we could zero the angular position reading if too much drift occurred throughout a match. Taking advantage of this anytime the robot was facing the proper direction in relation to the driver station helped keep the drift to a minimum and the driving experience as intuitive as possible.