Fractional-order fast terminal sliding mode control for nanopositioning

Abstract

A novel fast terminal sliding mode controller is proposed in this work for high-performance trajectory tracking at the nanometer scales. It combines a recursive integer-order non-singular high-order sliding manifold and a fractional-order fast fixed-time reaching law to ensure globally fast convergence, and adopts a time-delay-estimation based disturbance estimator deeming the designed controller robust to parameter uncertainty. The stability of the designed controller is verified through the Lyapunov framework, where the full analyses of convergence region and settling time are also presented. The tracking performance is experimentally verified on a piezo-stack-driven nano-positioning platform.