Questions about Encoders and PIDControllers

[Cal578]

Originally Posted by Ether

No, that's not how positional P-only works. With P-only, there would still need to be an output of sufficient magnitude to maintain a position against any external forces. With P-only, this output comes from the steady-state positional error.

We actually agree on this. I said the output would go to zero if the system reaches the setpoint. With P-only, the system will never reach and hold the setpoint; it can hold a steady error.

Originally Posted by Ether

Yes, they really are that different. If you are controlling position, then the plant is an integrating plant. If you are controlling speed, then the plant is not an integrating plant. They require different strategies.

That assumes you are always measuring distance, whether controlling position or speed. If you measure speed for speed control, and set your P, I, and D constants accordingly, it works out to the same concept.