Stability analysis of digital feedback control systems with time-varying sampling periods

We consider digital feedback control systems with time-varying sampling per iod's consisting of an interconnection of a continuous-time nonlinear plant (described by systems of first-order ordinary differential equations), a n onlinear digital controller (described by systems of first-order ordinary d ifference equations), and appropriate interface elements between the plant and controller (A/D and D/A converters). For such systems we study the stab ility properties of an equilibrium (in the Lyapunov sense) and derive some results for local stability and instability via a linearization approach. T hese results are then used in the analysis of certain classes of switched s ystems and in the stabilization problem of nonlinear cascade control system s via hybrid feedback controllers. (C) 2000 Elsevier Science Ltd. All right s reserved.