Model-free control of a 3-DOF piezoelectric nanopositioning platform

A model-free controller is designed for a nanopositioning platform with three degrees of freedom. The system is specially difficult to control because of the coupling between the different movements and the hysteresis present in the piezoelectric actuators. The authors propose a control design methodology based on the so called ultra-local system description. The developed controller has been implemented and validated on a real test bench and it has proven a good performance in handling the nonlinearities and uncertainties present in the platform.