ROBUST-CONTROL FOR SERVO-MECHANISMS UNDER INEXACT FRICTION COMPENSATION

Uncertainties in the parameters but also in the structure of the frict ion model may lead to inexact friction compensation in servo-mechanism s. This will lead to differences between the predicted friction and th e real friction forces, provoking, in certain cases (overcompensation) an oscillatory behaviour. This paper proposes a new control scheme se eking to strengthen the closed-loop system properties in the eventuali ty of friction overcompensation. This control design has the advantage that, in the case of friction overcompensation, the oscillations can be reduced in amplitude and modified in frequency independently of the closed-loop system specifications.