closed llop speed control on AX3500 for one channel only

The roborun alllows either both channel in closed loop speed control or none on AX3500. I want to put only one channel in closed loop speed control (through encoder) and keep another in open loop.

How can I do that?
If Roboteq can't do it, does anybody know another motor controller that can do that?

There are no settings in the controller for doing this.

However, you could achieve practically the same result by configuring the second channel in position mode, with encoder feedback and no encoder attached.

Then, you will set the P parameter to 1, I and D to 0.

When running, a command will cause the motor to spin at the command speed value.

This is because the controller will think the motor is always at position 0 (no encoder attached) and the power applied is equal to command - position (i.e, command - 0) multiplied by the P gain of 1.

Thanks Cosma,

I am just trying to do what you said. But I see only one set of gains in Roborun. That means the gains are same for both channel. If I set integral component (I) to zero, wouldn't it affect the performance of another motor running in speed mode?

You are actually correct. My answer was not totally thought through, and I is the key component for closed loop speed, so it cannot be 0.

You can experiment but I will need to get back to you with a better answer.

We have a beta version of the firmware that will let you configure each channel differently with different PID values.

If you are still interested, pls let us know.

Cosma,

I am from Oceanscience group and We have already discussed this firmware change with you and Tony and Alex. I think our purchasing guy will soon process the payment.