Nonsingular fast terminal sliding mode control of manipulator trajectory tracking based on adaptive finite-time disturbance observer

This study proposes a nonsingular fast terminal sliding mode control strategy based on an adaptive finite time sliding mode disturbance observer for trajectory tracking control of uncertain rigid manipulators with external disturbances. Firstly, an adaptive finite time sliding mode disturbance observer (AFTSMDO) is designed to suppress and compensate the total disturbance caused by the uncertainty of the manipulator model and external interference. The introduced adaptive law can estimate the centralized perturbation in real time, and the designed observer parameters are set independent of the specific value of the disturbances. Secondly, a new non-singular fast terminal sliding surface is proposed. By introducing the error cube term into the sliding mode surface, the approach law is improved by using the finite time theory, which greatly improves the fast convergence of tracking errors. Finally, the stability of the control system is proved in detail by using Lyapunov stability theorem and finite time stability theory. Through a specific simulation, the AFSMDO-NFTSMC control policy is applied to a 2-DoF manipulator to verify the effectiveness of the control strategy proposed in this paper.