Yaw Rate Sensor Drift?

[Mark McLeod]

Originally Posted by phrontist

When you say you used it as a yaw trimmer do you mean that it was used to correct the robots steering? I was thinking about this and I figured that the errors would build up to the degree that the sensors would give such faulty information that the robot would no longer be operable. I take it this isn't the case?

It works great as a yaw trim to correct stearing due to the relatively short distances involved in a single movement on the field. The drift error builds up over time so it affects absolute position the most because your comparison is to the original starting position of the robot and that gets further and further away in time as the game goes on and drift increases over time.

Yaw trimming on the other hand can be thought of as being broken up into separate distinct movements (like backing up, going straight ahead, then a curved forward or backward movement). Yaw trim doesn't require an absolute heading, but a relative one. Each distinct movement applies the gyro from only the beginning of that distinct motion which is a much shorter time for drift to have an opportunity to enter the equation.
For instance, suppose that halfway through a match the gyro drift results in a cumulative error of 5 degrees. The driver starts a forward movement in the original starting direction, but the RC uses the new gyro output of 5 degrees as the heading to maintain. If you're at the end of autonomous and start driving a new direction then you might be pointed in the wrong direction overall because of the total drift, but you'll drive straight as an arrow for that one motion.