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Online Control Reconfiguration for Manufacturing Systems
Published in Javier Campos, Carla Seatzu, Xiaolan Xie, in Manufacturing, 2018
The approach of this chapter differs from the existing ones firstly by the model class, namely, I/O automata. This modelling approach is motivated by the fact that I/O automata explicitly describe the action–reaction principle (causality) which is a fundamental property of technological systems. The control problem has been solved for standard automata through the supervisory control theory (SCT). One idea would be to adopt the existing relation between I/O automata and standard automata [12] in order to deduce an I/O controller from the SCT-based supervisor. A similar approach has been proposed by [23,24] for DES with partial observations. The resulting I/O controller is a Moore automaton. In our framework (Figure 23.1), this way would lead to an open-loop control structure because the control signals wc would be generated regardless of the outputs wp of the plant but depending only on the internal state zc of the controller due to the Moore property of the controller.
How selfish individuals achieve unselfish goals: majority-based progressive control of discrete event systems
Published in International Journal of Control, 2020
Supervisory control is a feedback control for discrete event systems (DESs) of which state transitions happen by irregularly occurring events (Ramadge & Wonham, 1987). It provides systematic ways to achieve desirable behaviours by enabling or disabling controllable events following the observation of system behaviours. Supervisory control theory can be applied to many dynamical systems including power systems (Afzalian, Niaki, Iravani, & Wonham, 2009), biological systems (Baldissera, Cury, & Raisch, 2016), manufacturing systems (Hu & Zhou, 2015), economic systems (Park, 2011), and software systems (Phoha, Nadgar, Ray, & Phoha, 2004). In this paper, we present a new supervisory control framework called majority-based progressive control inspired by a principle of democratic progress, namely, making more people meet their interests or rights. For this purpose, we suppose that local supervisors have their own private specifications as well as an additional global specification which the overall system must achieve. The aim of progressive control is to increase the number of local supervisors meeting private specifications as the controlled system undergoes transitions. Here, the progressive behaviour means that the number of local supervisors meeting private specifications is not strictly increasing, but non-decreasing with at least one transition at which the number increases. This notion is targeted to imitate the gradual development of democracy.