Q:

How can I damp oscillating behaviour caused by quantization in a digital control system?

After introducing a quantization block in the simulink model, the output of the controlled system starts to oscillate around the zero fixpoint.
I am using a lqr controller to regulate the system, which was designed based on the continuous system. 
Can I tune the parameters of the lqr design to fix this problem ? Which method is recommended here ?

A:

The typical method is to choose hardware whose quantization is lower than the system's ambient noise.
You can't damp it out -- it's a nonlinear phenomenon, which, when linearized around a switch in the output, has infinite incremental gain.  If for some reason you can't just make the quantization small enough, you can add some dither to it -- either add a sawtooth right before the worst quantization step, or implement a delta-sigma modulator (a 1st-order is enough in my experience).

