Position and torque control of AC servo motor

[siha]

I have an AC servo motor attached to a steering wheel. The torque reaction will be produced proportional (linear relation) to the steering wheel angle. There is no torque sensor in the system but an encoder. When the steering wheel is released at some angle, it will return to center (zero) position. I have designed a PID control for the position. Is it possible to control the position and torque of the motor at the same time? If it is, how can I make it? Also, can I make it without using a torque sensor?

[Erik-S]

Hi Siha,

What kind of hardware are you using to control the motor? In theory, you could probably use torque feedback to control the position, or vice versa, but you cannot do both at the same time as far as I know. It may be possible to estimate the torque based on the position if you have a robust linear relation, but I am not sure of any precedent (or examples I could point you to) for that.

-Erik S