Showing papers by "W. M. Wonham published in 2020"

Exploiting Symmetry of Discrete-Event Systems by Relabeling and Reconfiguration

Abstract: Symmetric discrete-event systems (DESs) are composed of groups of identical components (machines) and buffers. As every component in each group has the same structure, they can be relabeled to a prototype machine. With respect to buffer specifications (prohibiting overflow and underflow) it is shown that optimal supervisory control of the original DES (with many machines) can be reduced to control of the much smaller collection of prototype machines. With buffer sizes fixed, the result is a small invariant supervisor which is independent of the total number of original machines. We analyze the underlying reason for this invariance property and apply the result of the invariant reduced supervisor to efficient reconfiguration triggered by the addition or removal of machines and increase or decrease of the buffer capacity.

Failsafe mechanism design of multicopters based on supervisory control theory

Abstract: In order to handle undesirable failures of a multicopter, which occurs in either the pre-flight process or the in-flight process, a failsafe mechanism design method based on supervisory control theory (SCT) is proposed for the semi-autonomous control mode. The failsafe mechanism is a control logic that guides what subsequent actions the multicopter should take, by taking account of real-time information from guidance, attitude control, diagnosis and other low-level subsystems. In order to design a failsafe mechanism for the multicopters, safety issues of the multicopters are introduced. Then, user requirements including functional requirements and safety requirements are textually described, where functional requirements guide the modelling of a general multicopter plant, and safety requirements cover the failsafe measures dealing with the presented safety issues. Based on these requirements, several multicopter modes and events are defined. On this basis, the multicopter plant and control specifications are modelled by automata. Then, a supervisor is synthesized by using SCT. In addition, the authors present three examples to demonstrate the potential conflicting phenomena due to the inappropriate design of control specifications. Finally, based on the obtained supervisor, an implementation method suitable for multicopters is presented, in which the supervisor is transformed into decision-making codes.

Composite supervisory control for symmetric discrete-event systems

Abstract: In symmetric discrete-event systems, the system complexity is reduced by relabelling to the same symbol events fulfilling the same task In this paper, we divide specifications into two classes: pu

Bidirectional Dynamic Reconfiguration of Discrete-Event Systems *

Abstract: We study the fundamentals of bidirectional reconfiguration for discrete-event systems with an arbitrary number of modes. Our approach is to construct reconfiguration specifications based on analysis of plant components and generate a reconfiguration plant. The latter is the synchronous product of the original plant and the reconfiguration specifications. As a result, a reconfiguration is always defined at states that belong to both the source mode and the target mode. Besides, the resulting reconfiguration plant is compact, nonblocking, and compatible with supervisory control under behavioral specifications.