PID Tips and Tricks

P.I.D.'s are a common trouble area for Idle control, O2 feedback, boost control, and Electronic Throttle control.

Error Gain - All of the PID gains are multiplied by this number. If you set this to zero, it will turn off the PID feedback. This is handy for dialing in base settings like boost control or idle base settings.

P - Proportional - There are 2 parts to the proportional part of the PID control, the gain, and the gain tables. The key to fast smooth response is the gain tables. Use the straght gain number for over all proportional response. The gain table is based on error both positive and negative, so you can have the system work fast one direction, and slow the other if you choose. Remember Proportional gains make the big jump when your off of target.

I - Integral - Same as the proportional...2 parts, Integral gain, and Integral gain table. Think of integral as a trim to get you to target. Integral will 'wind' itself like a rubber band, so you want your gain high close to target, and low at larger errors... something like this .... .5, .75, 1, 1.5, 2,3,2,1.5,1,.75,.5 for the gain table. This is effectively the opposite of your Proportional gain table.

D - Derivative - Same 2 parts (in most cases). Think of Derivative as a damper when approaching the target. Derivative gains are NOT used on dynamic feedback systems (which is what we mostly have in Idle, O2, boost, and ETC feedback). So typically your D gain is set to zero, or maybe .01. If you notice you are getting really close to your target and aren't quite getting there, or your feedback loop is pausing on it's way to target...shut the D gain down to zero. I run all of my D gains at zero on all of the PID loops that I do.

Interesting how you describe setting up the Integral Erro table. Have you successfully set the table up like this and have it work effectively? Everything I've seen that you've helped set up (mainly for Supras) has that table set up the same as the Proportional Error table.

Turbo98 wrote:

Interesting how you describe setting up the Integral Erro table.  Have you successfully set the table up like this and have it work effectively?  Everything I've seen that you've helped set up (mainly for Supras) has that table set up the same as the Proportional Error table.

This is how I set up the I Gain table on everything I do...some are more or less sensitive and that will change the numbers, but the idea remains the same.

Admin wrote:

Turbo98 wrote:

Interesting how you describe setting up the Integral Erro table.  Have you successfully set the table up like this and have it work effectively?  Everything I've seen that you've helped set up (mainly for Supras) has that table set up the same as the Proportional Error table.

This is how I set up the I Gain table on everything I do...some are more or less sensitive and that will change the numbers, but the idea remains the same.

Great.  Thanks.  Interesting concept that makes good sense.