Output-feedback control of precision motion systems with uncertain nonlinearities

We propose output-feedback tracking control with an extended high-gain observer-based feedback control for a class of precision motion systems that include unknown rate-dependent hysteresis nonlinearities with linear dynamics. The proposed control system has a number of features; namely, (i) it can guarantee ultimate boundedness of the tracking error, where the ultimate bound can be made arbitrarily small, for any given initial conditions and for bounded unknown exogenous inputs and modeling parameters, (ii) it provides the possibility of shaping the transient response of the closed-loop system as desired, and (iii) the proposed technique is non-adaptive inversion free technique. To verify the effectiveness of these results, first simulation results are provided for an iron pendulum in a magnetic field system. Then, the output-feedback approach is also applied experimentally to a piezotube micropositioning actuator for a precision motion control. (C) 2020 Elsevier Ltd. All rights reserved.