Tuning PID

[AustinSchuh]

Originally Posted by TimTheGreat

How much do I increase it by? 1?

And how do I know when the P value is tuned? It seems to work, but is there a way I could make it work "better"?

There are a couple answers I usually give to this.

1) Don't use I unless you have tried P and D extensively and can't get it to converge to the actual goal but can get it to converge close but not close enough. I rarely use I on 971's robots, and when I do, the loops end up being much more complicated and hard to reason about.

2) Start with 0.00001 for P (then D then I) and multiply them by a factor of 2 each time. I tend to round from 4 to 10 when multiplying to keep it easy. You'll quickly cover the space and learn what matters. One of my colleagues just multiplies by 10 each time.

3) Use the method recommended by plnyyanks


You can also choose to gain-schedule your PID gains based on if you are above or below the goal. That would mean that you have 2 different coefficients depending on if the arm is below or above your setpoint. Unless you have mastered normal PID, I wouldn't try this. (I needed to do this on 254's 2011 elevator and claw to get them to converge nicely with PD)