Friction characterization and compensation in electro-mechanical systems

Friction characterization is a prerequisite for an accurate control of electromechanical systems. This paper considers the identification and control of friction in a high load torque DC motor to the end of achieving accurate tracking. In the first place, model-based feedforward controllers for friction compensation are considered. For this purpose, friction model structures ranging from the classical Coulomb model through the recently developed generalized Maxwell slip (GMS) model are employed. The performance of those models is compared and contrasted in regard both to identification and to compensation. Subsequently, having an accurate model of the system, model-based feedback controllers are also considered, namely the DNPF and the gain scheduling controllers. We show further that the gain scheduling controller yields best performance.