Experimental comparison of disturbance observer and inverse-based hysteresis compensation in 3D nanopositioning piezoactuation

This paper presents an illustrative experiment-based comparison between different approaches for hysteresis compensation in piezoelectric actuators (X and Y axes). The focus is on 3D piezoactuation on some lab-made nanopositioning device, based on tunneling current phenomenon (Z axis). The experimental validation is done for two formerly developed methods - operator-based Modified Prandtl-Ishlinskii (MPI) inversion on the one hand and disturbance observer (DOB) affine hysteresis approximation on the other hand, as well as for the one corresponding to DOB based on MPI hysteresis approximation. It is shown that the modeling error introduced by MPI model is bounded and the MPI compensator in a forward path of the considered system can improve the performance of DOB. The results are given for tracking spiral patterns recently used in Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM).