On Regional Sampled-Data Control of Nonlinear Time-Delay Systems with Input Saturation Constraints

In this paper, we deal with the stabilization problem of nonlinear time-delay systems affected by input saturation constraints via sampled-data dynamic output feedback controllers. Nonlinear time-delay systems not necessarily affine in the control input are studied. A new approach for the design of sampled-data dynamic output feedback controllers is provided taking into account the effects of input saturation constraints. In particular, it is shown that the digital implementation via suitable approximation functions of dynamic output steepest descent feedback (continuous or not) with amplitude bounds yields the practical stability, with arbitrarily small final target ball, of the related sampled-data closed-loop system limited to suitably small regions. The case of time-varying sampling intervals and the stability analysis of the inter-sampling system behavior are included in the theory here developed. The provided results can be applied also for nonlinear delay-free systems which are here addressed as a special case. An example is presented which validates the theoretical results.