High-precision control of positioning systems with nonsmooth nonlinearities

A high-precision control scheme for a precise point-to-point positioning system under the influence of nonsmooth nonlinearities is proposed. The proposed scheme consists of two controller modes: a tracking controller mode and a two-layered controller mode. The tracking controller is composed of a friction compensator, a linear feedback controller and a sliding control. The friction compensator is designed based on an identified friction model by using evolution strategies. The two-layered controller consists of a fuzzy precompensator and a PD controller. The fuzzy precompensator is employed to improve the performance of the PD controller. Its fuzzy rules are obtained from experimental evolutionary programming, not from an expert.