Velocity PID Programming: Terms dependent on time

[Tom Line]

Thanks - the pseudocode is corrected.

While I understand running in a forced timing loop will get good results, forced timing in LabVIEW results in a very high processor utilization.

"Waited" loops are only a minimum. For instance, if you have a 20ms loop and your timing control is a 20 ms wait, the actual loop execution time is never shorter than 20ms, but can be as long as it likes.

Forcing priority so that a loop runs at consistent timing last year added 10-15% processor utilization. As a result, we'd like to use the more elegant solution and account for time in our velocity PID calculation.

After glancing back at my notes from last year to confirm it, both the integral and the derivative of a PID loop require time normalization. That means the velocity term itself in a velocity PID should need it as well (and I'm guessing on that), the integral should not (integral of velocity is position), but I don't know about the derivative term, acceleration, though I would guess it should as well.

The internet is woefully light on velocity PID documents that a layman can get info from.

What the heck is the integral term in a position PID anyway? How do you integrate position?