Supervisor for toner error handling : a case study in supervisory control of Océ printers

The purpose of this report is to demonstrate the viability of supervisory control synthesis approach by presenting the formulation and a preliminary solution of a real-life control problem in Oce printers. In a nutshell, supervisory control synthesis is a procedure for automatic generation of control algorithms based on the formal model of the underlying system (plant) and of the requirements the controlled system has to satisfy. The underlying theory guarantees that the generated control algorithm will indeed force the system to meet the specified requirements, provided that the model of the system and of the requirements are accurate enough. The viability of the approach is demonstrated by applying it to a particular use-case of Oce, the toner error-handling problem. The presence of continuous-time behavior in the current use-case compelled us to use supervisory control theory in a novel way. Usually, when applying supervisory control theory, the plant is modeled as an automaton and this automaton is constructed manually. Instead, here we generate the finite-state automaton model by a computer program, which takes as inputs the value of a number of physical parameters.The reason for choosing to generate the model by a program is that the model is obtained by discretizing a hybrid model in time. In turn, the time-step used in the discretization of the hybrid model is one of the parameters of the computer program. By generating the model automatically, we are able to experiment with supervisors for different discretization time steps and different values of physical parameters

Supervisor for toner error handling : a case study in supervisory control of Océ printers

The purpose of this report is to demonstrate the viability of supervisory control synthesis approach by presenting the formulation and a preliminary solution of a real-life control problem in Oce printers. In a nutshell, supervisory control synthesis is a procedure for automatic generation of control algorithms based on the formal model of the underlying system (plant) and of the requirements the controlled system has to satisfy. The underlying theory guarantees that the generated control algorithm will indeed force the system to meet the specified requirements, provided that the model of the system and of the requirements are accurate enough. The viability of the approach is demonstrated by applying it to a particular use-case of Oce, the toner error-handling problem. The presence of continuous-time behavior in the current use-case compelled us to use supervisory control theory in a novel way. Usually, when applying supervisory control theory, the plant is modeled as an automaton and this automaton is constructed manually. Instead, here we generate the finite-state automaton model by a computer program, which takes as inputs the value of a number of physical parameters.The reason for choosing to generate the model by a program is that the model is obtained by discretizing a hybrid model in time. In turn, the time-step used in the discretization of the hybrid model is one of the parameters of the computer program. By generating the model automatically, we are able to experiment with supervisors for different discretization time steps and different values of physical parameters

Integrating continuous-time and discrete-event concepts in modelling and simulation of manufacturing machines

Using simulation models for the development and testing of control systems can have significant advantages over using real machines. This paper demonstrates the suitability of the ¿ language for modelling, simulation and control of manufacturing machines. The language integrates a small number of powerful orthogonal continuous-time and discrete-event concepts. The continuous-time part of ¿ is based on DAEs; the discrete-event part is based on a CSP-like concurrent programming language. Models are specified in a symbolic mathematical notation. A case study is presented of a transport system consisting of conveyor belts.

Linearization of hybrid Chi using program counters

The language χ was developed some years back as a modelling and simulation language for industrial systems [1, 2]. Originally, the language χ included fea-tures for modelling discrete event systems only. Later on it was extended with features to model dynamic behavior of a system as well [3, 4]. Hybrid χ wa

Towards a concurrency theory for supervisory control

In this paper we propose a process-theoretic concurrency model to express supervisory control properties. In light of the present importance of reliable control software, the current work ow of direct conversion from informal specication documents to control software implementations can be improved. A separate modeling step in terms of controllable and uncontrollable behavior of the device under control is desired. We consider the control loop as a feedback model for supervisory control, in terms of the three distinct components of plant, requirements and supervisor. With respect to the control ow, we consider event-based models as well as state-based ones. We study the process theory TCP as a convenient modeling formalism that includes parallelism, iteration, communication features and non-determinism. Via structural operational semantics, we relate the terms in TCP to labeled transition systems. We consider the partial bisimulation preorder to express controllability that is better suited to handle non-determinism, compared to bisimulation-based models. It is shown how precongruence of partial bisimulation can be derived from the format of the deduction rules. The theory of TCP is studied under nite axiomatization for which soundness and ground-completeness (modulo iteration) is proved with respect to partial bisimulation. Language-based controllability, as the neccesary condition for event-based supervisory control is expressed in terms of partial bisimulation and we discuss several drawbacks of the strict event-based approach. Statebased control is considered under partial bisimulation as a dependable solution to address non-determinism. An appropriate renaming operator is introduced to address an issue in parallel communication. A case for automated guided vehicles (AGV) is modeled using the theory TCP. The latter theory is henceforth extended to include state-based valuations for which partial bisimulation and an axiomatization are dened. We consider an extended case on industrial printers to show the modeling abilities of this extended theory. In our concluding remarks, we sketch a future research path in terms of a new formal language for concurrent control modeling