Adaptive Pulse Width Control for Precise Positioning Under the Influence of Stiction and Coulomb Friction

Abstract

Conventional linear digital control fails to provide precise positioning of a control object under the influence of static friction, Coulomb friction, and backlash. This paper presents an adaptive pulse width control (PWC) scheme for a precise point-to-point positioning system. This scheme is developed based on the relationship between the displacement of a control object due to a single pulse input and the pulse width. The coefficient appearing in this relationship is estimated by a parameter adaptation algorithm. Sufficient conditions for asymptotic stability of this adaptive scheme are developed using Popov hyperstability theorem. This adaptive PWC is tested on a laboratory positioning table and is shown to be effective.