Novel Sampled-Output Feedback Controller Guaranteeing Lyapunov Stability for Continuous-Time Uncertain Nonautonomous Nonlinear Systems

A novel output-feedback digital controller designed for continuous-time completely unknown nonlinear systems with inherent uncertainties is proposed in this letter. It addresses a broad class of general time-varying nonlinear systems characterized by significant unstructured uncertainties. Unlike previous methods, this controller does not require discretization of the controller or the controlled plant and is not limited to specific systems like Lur'e-type systems or upper-triangular nonlinear plants. Leveraging a discrete differentiator, it is rigorously demonstrated that the proposed digital control input, processed through a zero-order hold, ensures Lyapunov stability of the hybrid closed-loop system.