Robust Time-Delay Force Control for Piezoelectric Actuators without Hysteresis Dynamics

Accurate force output control of piezoelectric actuators (PEAs) is particularly important in piezo-driven devices. Existing control methods are mostly designed based on system models and require complex parameter identification process, resulting in low control accuracy and poor robustness. Therefore, this work proposes a robust model-independent time-delay force tracking control scheme for PEAs without hysteresis dynamics. The designed control is mainly composed of three parts: 1) a desired error dynamics term based on fast nonsingular integral terminal sliding mode, which ensures fast convergence and high tracking accuracy; 2) a time-delayed estimation (TDE) part that avoids the continuous nonlinearities and realizes the model-free control; 3) a correction part on the basis of the fuzzy logic system (FLS), compensating the TDE error induced from discontinuous nonlinearities and improving the robustness. The stability and finite time convergence of the control system are given using the Lyapunov stability principle. Experiments demonstrate that compared with the conventional TDE-based force tracking control methods, this control scheme has faster converging speed and higher accuracy.