Friction Identification and Compensation in a DC Motor

Friction modeling and identification is a prerequisite for the 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. Model-based friction compensation in the feedforward part of the controller is considered. For this purpose, friction model structures ranging from the simple 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. It turns out that the performance depends on the prevailing range of speeds and displacements, but that in all cases, the GMS model scores the best.