I purchased a roboclaw 2x30 and the info page says it has been updated to include absolute position with pot feedback. The manual linked doesn’t say this however or how to command the device to go to a positon. Neither does the mfg website link.
The version of datasheet we have does not explain how to use a potentiometer for position feedback. You might try contacting the manufacturer, Orion Robotics, directly for additional assistance.
I contacted Orion Robotics recently with basically the same question and this is what they said:
[quote]We just updated our manual with the new position PID commands so you may have missed them. Also the manual doesn’t show an example of using the Position PID system yet. We are working on new updates to the manuals.
You can set the Roboclaw to use absolute (i.e. pots) instead of incremental encoders. Then you would need to tune the position PID coefficients. Velocity PID can be used along with the position PID but isn’t required. You just have to set the QPPS and zero the other velocity PID coefficients if you just want a position controller.
One of the ways the position PID has been tested was by gutting the motor driver from an RC servo and controlling the servo directly from the Roboclaw using the servos built-in POT.
Incremental encoders can also be used with position PID but you will have to home and zero the encoders if you go that route.[/quote]
Knowing at least that it is capable of this, I have since purchased one and will be trying to figure out how to do this from what little the manual does say about this form of position control. If I manage to get something working before Orion releases a new manual, I’ll post back with details.
Did you succeed in obtaining position control?
I too am having a lot of difficulty in using it in this manner.
What do we need to set the QPPS to if we are only using a pot?