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Unread 12-21-2012, 08:59 PM
Jared Russell's Avatar
Jared Russell Jared Russell is offline
Taking a year (mostly) off
FRC #0254 (The Cheesy Poofs), FRC #0341 (Miss Daisy)
Team Role: Engineer
 
Join Date: Nov 2002
Rookie Year: 2001
Location: San Francisco, CA
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Re: Motion Profiling

A perfect motion profiler (and appropriate controller) will get you to your goal at least as fast as any other method. If the acceleration limit in your profiler is right on the cusp of the stick-slip point for the wheels, you have essentially implemented a form of traction control for your robot.

Of course, the stick-slip point depends on a lot of things (tread wear, carpet irregularities, the amount of weight being carried by each wheel instantaneously, etc.), so in practice you usually want to back off on the acceleration limit by a safety margin. The extra repeatability is worth the handful of milliseconds longer it takes for your robot to get to its goal.

In general, if all your feedback controller is doing is removing noise/error from your planned trajectory, you're going to have a good time. This is why feedforward gains are so powerful - in the absence of any disturbances, you theoretically will get exactly where you want to go without needing ANY feedback!

Last edited by Jared Russell : 12-21-2012 at 09:01 PM.