Model-based adaptive friction compensation for accurate position control

An adaptive friction compensator for position control is proposed using the generalized Maxwell-slip (GMS) friction model, with a new, linearly-parameterized Stribeck function. It employs a polynomial equation that is linear-in-the-parameter to approximate the nonlinear Stribeck effect in the GMS model, and simplifies the design of the adaptive friction compensator. The proposed compensator has a switching structure to accomodate for the hybrid nature of the GMS model, and contains a robustifying term to account for unmodelled dynamics. The stability of the proposed adaptive algorithm is analyzed and its stability conditions are clarified. The validity and effectiveness of the proposed, linearly-parameterized friction compensator is verified by simulations for the positional control of an inertia system under the influence of dynamic friction.