Hi,
In my current setup I'm using the FAST observer and that works pretty descent, but I sometimes observe some resonances at several frequencies (you can feel the motor shaking at several Hz), that I'm not really get rid of by tuning the PI Speed Controller and the PI Current Controller bandwidth.These frequencies can be at low and medium speeds of the motor and are stronger, as stiffer I tune the PI Speed Controller (of course). The setup is using the universal motor control lab. I tried also different motors (different size, different torque constants etc.) and also different CSA (INA240A1 is the best so far), but I never really got rid of the oscillations at some frequencies. I also tried a 2500PPR encoder and it seems to performe pretty much the same as with FAST at medium speeds (500-3000rpm). When I then use the position control mode (Kp controller) with a trajectory generator, I cannot tune the system to have a position deviation of less than 1.5PU @3000rpm without heavy resonances of the system.
Now I would like to eliminate these resonances and still use a pretty stiff system, so I'm thinking about using a High Resolution SSI Encoder (something like 17bit), but I'm unsure if the performance would be better than with FAST. Can you tell me, how good the performance of the FAST observer at medium speeds (500-3000rpm) is in comparison to a High Resolution Encoder? Can such a encoder improve performance in terms of resonance?
