Closed loop position control in CAN

[chi-town-biker]

We’ve used CAN in previous years and like it. This year we plan on using closed loop limit switches and position control. We’re unsure whether to use an encoder or potentiometer based position control. Does anyone have any experience and advice on which to choose? Which is more accurate? Easier to use? Any difference in tuning the PID? Thanks for any help.

[gpetilli]

Since you mention CAN, I assume you are using the PID on the Jaguar.
For position control, we prefer the potentiometer over an encoder mainly since it maintains the home position through power cycles. Depending on your application, the encoder will likely need a limit switch and a power up calibration to find home. We have been successful using a pot tied to the Jaguar running PID in the past - however if the load is asymmetric (think arm working against gravity going up vs. with gravity going down) it is difficult to stabilize with the textbook PID in the Jaguar.

[chi-town-biker]

Thanks. That was very helpful. I didn't realize we'd have to initialize an encoder every time we powered up.