Design of adaptive super twisting tracking controllers for perturbed nonlinear systems with input constraints

This paper proposes an adaptive super-twisting control design method to solve tracking problems for a class of perturbed MIMO nonlinear systems under the condition of input constraints. A partial state’s observer is firstly designed to estimate the unmeasurable states. Then, one designs a sliding surface function and crafts an adaptive super-twisting sliding mode controller under the constraints of input saturation for solving the tracking problems. The signs of the upper and lower bounds of the input saturation functions are not restricted to positive and negative respectively. Under certain conditions, the tracking errors and state estimation errors are all tend to zero within a finite time. Furthermore, there is no need to know the upper bounds of perturbations beforehand due to the usage of adaptive mechanisms embedded control both in the scheme and the state’s observer. An application example is given to demonstrate feasibility and effectiveness of the proposed control scheme.