Design of fixed-time adaptive super twisting controllers for perturbed nonlinear systems.

In this paper a design methodology of fixed-time adaptive super twisting control is proposed for a class of multi-input nonlinear systems with matched and unmatched perturbations to solve the fixed-time regulation problems. The sliding surface is firstly designed, and then the super twisting controller is designed accordingly. The perturbation estimation and adaptive mechanisms are also embedded in the proposed control scheme, so that there is no need to know the upper bounds of perturbations as well as perturbation estimation error in advance. Hence applying excessive control input energy to systems is also avoided due to utilisation of perturbation estimator. Moreover, choosing appropriate design parameters is also addressed in detail in order to meet the required fixed-time convergent time. Finally, a numerical example is given for demonstrating the feasibility of the proposed control strategy. [ABSTRACT FROM AUTHOR]