Alternative to PID speed control

[Ether]

Originally Posted by martin417

We used a very simple closed loop control that worked flawlessly. We had a jag on CAN bus with an encoder attached to the jag. We used voltage control with a voltage ramp of ~115 V/S. We queried the jag for speed, and if the speed was less than the set speed, we set max voltage. If the speed was greater than or equal to set speed, we set zero voltage. The inertia of the system kept the shooter speed within ~15 RPM of set speed at all times, and when we shot, the voltage immediately went to full for rapid spin-up.

the simplest solution that works is usually best.

I've been wondering if that would work for this application. I did something very similar for an automotive actuator I worked on several years ago.

Thanks for posting that.

PS - I assume you had the Jag jumper set for coast?

[martin417]

Originally Posted by Ether

...PS - I assume you had the Jag jumper set for coast?

Yes, coast.

[Cal578]

This feed-forward idea sounds helpful. If I understand correctly, PID alone can be done in the Jaguar via CAN, but PID with feed-forward would need to be implemented entirely in the cRIO. The Jag PID doesn't have any way to add a feed-forward value. Did I get this right?

[Ether]

Originally Posted by Cal578

The Jag PID doesn't have any way to add a feed-forward value. Did I get this right?

Yes. See this post:

http://www.chiefdelphi.com/forums/sh....php?p=1108556