Adaptive friction compensation for systems with generalized velocity/position friction dependency

The dynamic friction model proposed by Canudas de Wit et al. (1991) captures most of the friction behaviors that have been experimentally observed, which include the Stribeck effect, hysteresis, spring-like characteristics for stiction, and varying break away force. In this paper we deal with the problem of designing an observer-based adaptive friction compensation scheme for systems with generalized position/velocity static characteristics. The proposed controller yields global asymptotic stability of the tracking error while preserving boundedness of all the internal signals. We also explore several ways of selecting the basis functions for characterizing the friction position/velocity dependency: polynomial approximation, nonlinear functional approximation and neural networks