Friction Modeling and Compensation of Servomechanical Systems With Dual-Relay Feedback Approach

The application of a dual-relay feedback approach toward the identification of a model of servomechanical system will be presented in this paper. The model will capture the linear dynamics of the system, as well as the frictional forces affecting the system, through a comprehensive friction model that includes static friction, Coulomb friction, viscous friction, and the boundary lubrication velocity. This friction model is able to adequately describe the friction property when the servo system runs under both low- and high-velocity modes. Properties of the oscillations induced under the dual relay will be presented, based on which insights for the selection of relay parameters can be drawn. A systematic set of procedures to derive all the parameters of the model will be furnished. The model will be directly useful in the design of the feedback controller and feedforward friction compensator. Results from the simulation and experiment will be presented to illustrate the practical appeal of the proposed method.