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

The 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. 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 asymtotic stability of this adaptive scheme is developed using Popov hyperstability theorem. This adaptive PWC is tested on a laboratory positioning table and is shown to be effective.