On Controllability of Hybrid Systems

In this article, we investigate controllability of hybrid systems. We use hybrid machines to model such hybrid systems. The model consists of an automaton and a linear time-invariant system. The control goal is to drive the continuous state from any initial state to any final state. To achieve this goal, controls at both the discrete-event level and the continuous-variable level are used. Control at the discrete-event level can force some forcible events, and disable some controllable events. For the case that all events are controllable and forcible, and the graph of the automaton is strongly connected, a necessary and sufficient condition for controllability is obtained, using some existing results on controllability of switched linear systems. For three other cases, sufficient conditions are derived. If a hybrid system is not controllable, we design a supervisor to control the discrete-event part to ensure that the system becomes controllable after some finite transitions if possible. We find a necessary and sufficient condition for such a discrete-event control to exist.