Thread: Problems Using PID for Velocity
View Single Post
  #1   Spotlight this post!  
Unread 27-01-2006, 20:06
Astronouth7303's Avatar
Astronouth7303 Astronouth7303 is offline
Why did I come back?
AKA: Jamie Bliss
FRC #4967 (That ONE Team)
Team Role: Mentor
  
Join Date: Jan 2004
Rookie Year: 2004
Location: Grand Rapids, MI
Posts: 2,071
Astronouth7303 has much to be proud ofAstronouth7303 has much to be proud ofAstronouth7303 has much to be proud ofAstronouth7303 has much to be proud ofAstronouth7303 has much to be proud ofAstronouth7303 has much to be proud ofAstronouth7303 has much to be proud ofAstronouth7303 has much to be proud ofAstronouth7303 has much to be proud ofAstronouth7303 has much to be proud of
Question Problems Using PID for Velocity
We have a PID control loop to control velocity of a motor. We have the tooth counter giving us our current velocity, and an OI analog input giving us our target. The code is written such that the motor can never go backwards. (The tooth counters are giving us a speed of about 0-18, we're hoping to increase that range a little.)

The problem is that, when using only a P loop, it oscillates violently at mid- to low-speeds. Meaning that it revs up, then stops, revs up then stops, etc. (Victor set to coast.)

Anyone seen this before in their own code? Any recomendations on using PID for velocity->velocity control loops?