We demonstrate the use of a new, control-oriented notion of finite state approximation for a particular class of hybrid systems. Specifically, we consider the problem of designing a stabilizing binary output feedback switching controller for a pair of unstable homogeneous second order systems. The constructive approach presented in this note, in addition to yielding an explicit construction of a deterministic finite state approximate model of the hybrid plant, allows us to efficiently establish a useable upper bound on the quality of approximation, and leads to a discrete optimization problem whose solution immediately provides a certifiably correct-by-design controller for the original system. The resulting controller consists of a finite state observer for the plant and a corresponding full state feedback switching control law.
I. INTRODUCTION A. Motivation and OverviewFinite state approximations and abstractions of hybrid plants have been explored as a means for addressing instances in which the interaction between analog and discrete dynamics 1 leads to complex analysis and synthesis problems that cannot be adequately handled by traditional methods. Some of the early work in this area explored the use of 'qualitative' models, namely non-deterministic automata whose output behavior contains that of the original hybrid system [19]. In [21], an approach for deriving non-deterministic finite state approximations of systems with quantized outputs was proposed and used in conjunction with the supervisory control theory developed by Ramadge and Wonham [22] to design controllers meeting the desired specifications. Another line of research, inspired by formal verification techniques in computer science, explored the construction of deterministic discrete abstractions of hybrid systems [2]. Early work in this area focused on identifying classes of systems that admit finite bisimulation abstractions [11], [15]. Having recognized that these classes are fairly limited, more recent work has focused on finding discrete abstractions that are related to the original hybrid system by an approximate simulation or bisimulation relation [10], [25], [26]. The resulting controller design problem is then a two step procedure in which a finite state supervisory controller is first designed, and subsequently refined to yield a certified hybrid controller for the original plant [27].In this note, we demonstrate the use of a new 2 , alternative notion of approximation that, in addition to yielding a finite state deterministic approximate model of the original hybrid