Stability analysis for switched systems with continuous-time and discrete-time subsystems

We study stability property for a new type of switched systems which are composed of a continuous-time LTI subsystem and a discrete-time LTI subsystem. When the two subsystems are Hurwitz and Schur stable, respectively, we show that if the subsystem matrices commute each other, or if they are symmetric, then a common Lyapunov function exists for the two subsystems and that the switched system is exponentially stable under arbitrary switching. Without the assumption of commutation or symmetricity condition, we show that the switched system is exponentially stable if the average dwell time between the subsystems is larger than a specified constant. When neither of the two subsystems is stable, we propose a sufficient condition in the form of a combination of the two subsystem matrices, under which we propose a stabilizing switching law.