SYNTHESIS AND VIABILITY OF MINIMALLY INTERVENTIVE LEGAL CONTROLLERS FOR HYBRID SYSTEMS

In this paper, we study the control of Composite Hybrid Machines (CHMs ) subject to safety specifications. CHMs are a fairly general class of hybrid systems modeled in modular fashion as the concurrent operation of Elementary Hybrid Machines (EHMs). The formalism has a well-define d synchronous-composition operation that permits the introduction of t he controller as a component of the system. The task of a legal (safet y) controller is to ensure that the system never exits a set of specif ied legal configurations. Among the legal controllers, we are particul arly interested in designing a minimally-interventive (or minimally-re strictive) one, which interferes in the system's operation only when c onstraint violation is otherwise inevitable. Thus, a minimally interve ntive safety controller provides maximum flexibility in embedding addi tional controllers designed for other control objectives to operate co ncurrently while eliminating the need to re-investigate or re-verify t he legality of the composite controller with respect to the safety spe cification. We describe in detail an algorithm for controller synthesi s and examine the viability of a synthesized controller as related to the possibility of Zenoness, where the system can undergo an unbounded number of transitions in a bounded length of time.