LMI-based design of robust gain-scheduling control for precise slow motion in a servodrive

This paper presents a new control design method to solve the problem of uncertain friction compensation in robot joint control. A friction force observer is designed using local models of friction interpolated by mean of weighting functions. The estimated friction is used in a minor loop for a compensation purpose and the resulting dynamics after compensation are considered for the synthesis of robust gain scheduling control scheme with uncertain friction compensation assumptions. The performance of this method is verified by simulations and experiments performed on a robot joint.