Sampled-data control for nonlinear systems with mismatched disturbances: a non-recursive design framework

This paper investigates a class of general nonlinear systems perturbed in a mismatched structural disturbance and formulates a sampled-data state feedback control law in a non-recursive manner. A novel discrete-time (DT) observer is first proposed in this strategy to recognise the unknown perturbations. Then, by utilising the estimated information, a linear DT non-recursive controller can be constructed in one step. The biggest challenges lie in the estimation accuracy of the DT observer and the rigorous stability analysis of the hybrid closed-loop system. Besides, the distinguished feature of the proposed method is the ‘explosion of terms’ caused by step-by-step recursive design in the traditional recursive control approaches can be avoided. Furthermore, the DT composite control design is friendly to digital computer implementation. The effectiveness of the built control scheme is validated through some numerical simulations and an illustrative application example.