Adaptive compensation method of friction forces using differential estimator

This paper considers an adaptive tracking control problem for a positioning mechanism with friction. Almost of the previous adaptive control methods, the control strategy needs full-states measurements, such as position and velocity measurements. In general, only the position is measured by using position sensors, therefore, we have to make a velocity signals. To make a velocity signal component, an approximate differentiator and first order filter are often applied. But, unfortunately, it may cause deterioration of the control performance for the high ultra precision positioning control problems. This paper deals with adaptive friction compensation method that includes an adaptive differentiator which can estimate velocity signals without using approximated differentiator. The effectiveness of the proposed method is demonstrated by numerical simulations for the high ultra precision positioning control problems.