Fixed-time terminal sliding mode control for uncertain robot manipulators

This paper proposes a fixed -time tracking control for robot manipulators in the presence of parametric uncertainties and disturbances. An auxiliary function is first proposed for constructing a fixed -time sliding manifold. Benefited from this fixed -time sliding manifold, a singularity -free robust control is proposed to evade the effects of algebraic loop problem of the commonly -used sliding mode controls (SMC). The key advantages of the proposed approach are: (i) exact fixed -time stability featuring the convergence time does not relate to the initial conditions and is acquired in advance; (ii) the singularity and algebraic loop problems are eliminated completely; (iii) a simple and intuitive control structure is used for easy implementation of trajectory tracking control for uncertain robot manipulators with faster transient and higher steady-state precision. Simulations and experimental comparisons validate the improved tracking performance of the proposed approach.