Analysis and model-based control of servomechanisms with friction

Friction is responsible for several servomechanism problems, and their elimination is always a challenge for control engineers. In this paper, feedback model-based compensation of friction is used for servomechanism set point and tracking tasks. Basic friction models are tested and their influence on system response is examined using describing function analysis. Analytical predictions are compared to simulations and experimental results. Various control laws using friction compensation are compared experimentally. Results showed that for both types of tasks, the best response is obtained by a model-based control law with friction compensation using the general kinetic friction model.