A novel robust fixed-time fault-tolerant tracking control of uncertain robot manipulators

This paper presents a novel robust fixed-time fault-tolerant control for global fixed-time tracking of uncertain robot manipulators with actuator effectiveness faults. With the sufficient consideration of the effects on uncertain dynamics, external disturbances and actuator effectiveness faults to the trajectory tracking performance, a singularity-free robust fault-tolerant control with an auxiliary vector is constructed for the fixed-time tracking control of uncertain robot manipulators. Lyapunov stability theory is employed to prove the global fixed-time stability ensuring that both the position and velocity tracking errors converge globally to the origin within a fixed time. The appealing advantages of the proposed control are as follows: (i) it is easy to implement with the global robust fixed-time fault-tolerant tracking control for uncertain robot manipulators featuring with faster transient convergence rate and higher steady-state tracking precision; (ii) the settling time is independent of the initial states of closed-loop system and can be calculated in advance for robot manipulators with uncertain dynamics, external disturbances and actuator faults. Extensive simulations on a two-DOFs robot are presented to demonstrate the effectiveness and improved performances of the proposed approach.