Fixed-time nonsingular terminal sliding mode control for trajectory tracking of uncertain robot manipulators

This paper investigates the fixed-time trajectory tracking problem for uncertain robot manipulators and proposes a fixed-time nonsingular terminal sliding mode controller. First, an adaptive disturbance observer is constructed to estimate the unknown lumped disturbance in fixed-time. Then, a nonsingular terminal sliding mode surface is developed by introducing the auxiliary function. Based on the designed sliding mode surface and disturbance observer, a continuous fixed-time nonsingular terminal sliding mode controller is designed to ensure that the upper bound of the convergence time is independent of system initial conditions. Rigorous stability is given by utilizing the Lyapunov theory. Finally, numerical simulation results demonstrate the effectiveness and superiority of the proposed method.