A design of novel damping controller combined with PID for nanopositioners

A design of novel damping controller combined with proportion-integration-differentiation (PID) controller used in signal tracking for nanopositioners such as atomic force microscopes is proposed in this paper. This novel damping controller can damp the first resonant mode of a piezoelectric nanopositioning stage, at the same time, it can get finite-gain stability, rather than the loop gain should be strictly less than 1 by small-gain theorem. But it has big steady-state error. As we know, PID can almost eliminate steady-state error because of the existence of integral term, but the integral term leads to bigger vibrations in the steady-state. So a new control structure which combines a damping controller for a positive feedback with a PID controller for a negative feedback has been proposed. The results have been verified in our experimental platform and show that our method has better tracking effect compared with PID control or damping control alone.