Drivetrain PID tuning

[sspoldi]

Originally Posted by SamcFuchs

This is a good point, and I feel it would probably solve a lot of out problems. However, I haven't found a good way to get real time plots from the robot. Do you just use the smartdashboard?

We like to print to the console and either dump to an excel file or Octave script and do system ID on that.

We've gone almost exclusively to a PI controller for yaw rate for stabilization, since in teleop we're generally commanding yaw rate anyway. In autonomous we just program rate*time for heading changes, the integrator in the controller almost always gets us close enough. We've done heading control with feed forward for more bandwidth, but it was overkill for the particular application we tried it with. One of the first things we do in our gyro service function is to calculate (if necessary) and provide robot heading, and heading rate so that we don't need to derive it in a controller.

BTW, we generally run at 50 Hz, and target around 10 rad/sec for rate bandwith (a little less that 2 Hz). Our recent setups have been giving us around 30 millicesonds of delay between command and robot response, and 10 rad/s is about the point where we have to start to get more creative with a controller. We may try 100 Hz this year, depending on what we need to do.

Cheers,
Steve.