RobotC built in PID help

VEX V5 General Discussion General Forum
1

We are working with a single flywheel shooter using RobotC and are using the built in PID functions vs making our own. We are not quite to the level of making our own yet. SO… we have the P set at 65. At low speed it would oscillate at any lower P setting, but not is stable as far as ramping up at a setting of P = 65. Our I is at 5 and D is 0. It seems that no matter how much tuning… we cannot get the rpm to stay constant. It slows down slightly after each ball.

What would be the next course of action? in order to keep the rpm’s up, what would the best adjustments? I thought adjusting the I, but it just does not seem to be working that well. We have to find the sweet spot

2

My mentors are telling me that the I term is really not needed and that you could get away with a PD controller (set I to zero or something like that). The I term’s usually messy so see if that works for you.

3

Thanks. We will give it a try and hope it works!
Any more opinions?

4

I is used for continuous load, IE force needed to hold up a bar or w/e. Given that friction will constantly drag on the flywheel, I’d recommend a small amount of I.