Robust Sliding Mode Motion Control for Nonlinear Piezo-Driven Micropositioning Systems with Time-Varying Uncertainties

Piezo-driven micropositioning systems (PMSs) are prevalent in the high-precision manipulation fields, but also suffer from undesired nonlinear time-varying uncertainties, such as hysteresis, and parameter perturbation. To this end, this article proposes a novel sliding-mode-based robust control for a class of SISO nonlinear PMSs with time-varying uncertainties. Firstly, through a terminal-sliding-mode (TSM) surface with continuous, nonsingular, and finite-time convergence properties, a fast nonsingular TSM (FNTSM) control law is developed. Moreover, to avoid the shortage of the FNTSM control depending on the boundary information of system uncertainties, the Fourier series-based function estimation technique is adopted for dynamic approximation, and its approximation error is further compensated by the fuzzy logic system online. The updating laws of Fourier coefficients and fuzzy adjustable parameters are finally obtained via the Lyapunov stability theory. Numerical simulation results validate the reliability and superiority of the developed control strategy in comparison with the existing SMC methods.