Thread: PID: P+D or P-D
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Unread 27-01-2008, 23:52
Tom Bottiglieri Tom Bottiglieri is offline
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Re: PID: P+D or P-D
Quote:
Originally Posted by billbo911 View Post
I have a light grasp on the PID control concept. There is one portion of it that I have seen presented with contradictory information. Currently, I understand the purpose and function for all three parameters: P, I & D. In the control system we will be using, we plan on just using a PD loop.

Here is the question: I have seen the equation represented as (Perror*KP)+(Derror*KD), I also have seen it as (Perror*KP)-(Derror*KD). So which is it, and when would I use one or the other?
D should take off your attack, so it should be P - D. If Kd is negative, P+D works too.