Robust adaptive friction compensation

A new control scheme is presented which makes the closed-loop system properties robust under the eventuality of inexact friction compensation which may provoke limit cycles. This control design has the advantage that the possible oscillations can be reduced in amplitude and modified in frequency independently of the closed-loop system specifications. Also proposed is an approximate Tustin model, as a basis for the friction compensation, obtained by including a priori information about the lubricant coefficients. Simulations have shown that this model gives better accuracy than other models and that, together with the robust linear compensator, it improves adaptive transients