Cascaded torque (outer loop) and current (inner loop) control

[mawad]

Dear All,
I am wondering if it okay to have cascaded torque and current control loops to control the torque of a system driven by DC motor. The torque control will be the outer loop and has the set torque value and the current is the inner control loop on the DC motor. Is that okay? or it is better to have one control loop only for example the current loop and use the motor characteristics to estimate the system torque. I am looking forward to hear your suggestions

 

[PNachtwey]

The torque is almost directly proportional to the current. I don't see where you need cascaded control loops.

How would you measure the torque?

I would look at this

http://ctms.engin.umich.edu/CTMS/index.php?example=MotorPosition&section=SystemModeling

and this

http://deltamotion.com/peter/Mathcad/Mathcad - DC Motor Velocity.pdf

What are you really trying to do? The usual example for torque control is controlling the tension on a winding application.



Peter Nachtwey
Delta Computer Systems

http://www.deltamotion.com

http://forum.deltamotion.com/

 

[mawad]

Hello,
I have torque sensor based on strain gauges. I use it to measure the torque directly. I have a robot and I want to do torque control on its joints