Robust precision motion control of piezoelectric actuators using fast nonsingular terminal sliding mode with time delay estimation

Background: Piezoelectric actuators are widely used in many micro/nano-manipulation applications, but their positioning accuracy are badly affected by their inherent nonlinear hysteresis and creep. To solve this problem, this paper presents a new robust motion-control method for piezoelectric actuators with fast nonsingular terminal sliding mode based on time delay estimation. Method: The proposed controller needs no detailed information about the hysteresis and other nonlinearities of the system, leading to a simple and model-free characteristic due to the time delay estimation and ensures fast convergence and high tracking accuracy thanks to the nonsingular terminal sliding-mode surface and fast terminal sliding mode -type reaching law. A robust exact differentiator is adopted to estimate the velocity and accelerationinformation online, and it overcomes the limitation of only available position measurements. The finite-time convergence and stability of the closed-loop system are proved by using a Lyapunov function. Results: Experimental results show that the proposed control strategy has faster convergence and higher tracking precision compared with a traditional time delay control. Conclusion: The proposed control strategy can be widely used as an effective control method for high-precision motion control of piezoelectric actuators.