Fuzzy terminal sliding mode control of two-link flexible manipulators

This paper proposes a fuzzy terminal sliding mode control method for two-link flexible manipulators. Based on the singular perturbation method and two time-scale decomposition, the flexible manipulator system is firstly decomposed into two subsystems by modeling the joint angles and the corrected flexible modes as the slow and fast variables, respectively. A nonsingular terminal sliding mode manifold is proposed for the slow subsystem to realize fast convergence and better tracking precision. Meanwhile, a hybrid controller for the slow subsystem is proposed to ensure strong robustness, as well as to weaken chattering phenomenon using fuzzy logic. The fast subsystem is stabilized using a LQR control strategy. A reduced-order observer is proposed to estimate the corrected flexible mode variables that can not be measured directly. The simulation results are presented to validate the designed method.