Sliding-mode based force control of a piezoelectric actuator

In this paper force control of a piezoelectric actuator is presented. Force control based on a force observer is emphasized; however, results with a force sensor are also presented for comparison purposes. With the help of the proposed force observer, sensorless force control and estimation of environmental forces are realized. The force observer is first compared with the force sensor for different step motions to verify the capability of the force estimation. The observer output is then used for feedback of the force information in the closed-loop system. Experiments are made to validate the method.