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

In the present paper, we study robustness properties of a class of digital feedback control systems with time-varying sampling periods consisting of a n interconnection of a continuous-time nonlinear plant (described by system s of first-order ordinary differential equations), a nonlinear digital cont roller (described by systems of first-order ordinary difference equations), and appropriate interface elements between the plant and controller (A/D a nd D/A converters). For such systems, we establish results for exponential stability of an equilibrium (in the Lyapunov sense) in the presence of vani shing perturbations and for the boundedness of solutions (i.e., Lagrange st ability) under the influence of nonvanishing perturbations. We apply these results in the study of quantization effects. (C) 2000 The Franklin Institu te. Published by Elsevier Science Ltd. All rights reserved.