Sampled-Data Model-Free Adaptive Sliding Mode Control for Piezoelectric Actuators Subject to Time Delay

Abstract

This paper proposes a model-free sampled-data sliding mode control of piezoelectric actuators considering time delay. As time delay is a challenging subject in controller design, we try to eradicate its effect on the tracking performance of the control system as much as possible. For this goal, an equivalent sampled-data data-based model from the continuous-time nonlinear system of a piezoelectric actuator is first derived. Then, we include the delay of the control system into the sliding surface to enrich the controller performance. Next, the sliding mode controller is designed using the equivalent model and the delayed sliding surface. No observer is used to compensate for the total disturbances. Thus, the scheme is easy to design and implement. The stability of the closed-loop system is theoretically studied, and the controller performance is confirmed through comparative experimental tests. Based on the experimental results, the proposed controller successfully obtains control objectives.