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Unread 30-01-2013, 12:27
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AKA: James Killian
FRC #3481 (Bronc Botz)
Team Role: Engineer
 
Join Date: May 2011
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Re: Velocity PID Programming: Terms dependent on time

Quote:
Originally Posted by Tom Line View Post
Which of these terms need to be normalized by dividing them by the loop timing?
This is what we do:
m_error = (setpoint - input) * dTime_s; //Using dTime_s will keep the errors consistent if time is erratic

For us we do not use threads (tasks) for PID... we compute the time deltas and pass them throughout the entire loop. We usually stay between 10-12ms as there really shouldn't be much overhead to run.

This means we have large P I D terms... so 100 for P is about 1 for the usual standard. This may be a bit unorthodox but quite effective if you give it a try, as we found in last year's game for the shooter with non-linearized 884 victor's stress (ouch). Comments and criticism are welcome.

P.S. They are linearized off-season with help from the Simbot's poly but now all this may not matter with the new 888's

Last edited by JamesTerm : 30-01-2013 at 12:29.