D.E.D.S. Modelling and Knowledge-Based Control 1 (original) (raw)
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A Petri Net-Based Approach to Synthesis of Control Systems for Discrete Event Dynamic Systems
Elsevier eBooks, 1995
An approach to dealing with the synthesis of control of discrete event dynamic systems (DEDS) is presented. It simultaneously utilizes both the model of the discrete events system to be controlled and the knowledge representation expressing the control task specifications by means of a knowledge base (KB). Both the model and the KB are described mathematically on the base of an analogy with COrTe8ponding kinds of Petri nets.
Computer-aided design of intelligent control systems for discrete event dynamic systems
Proceedings of IEEE Symposium on Computer-Aided Control Systems Design (CACSD)
Thie paper presents a Petri nets-based approach to both modelling the discrete event dynamic systems (DEDS) to be controlled and the representation of knowledge about details or specifications concerning the control task. In order to synthetise intelligent control systems for the DEDS a procedure utilizing the Petri nets-baaed model of both the DEDS and the knowledge representation (both of them expressed in analytical terms) is proposed here.
Intelligent control of discrete event dynamic systems
Proceedings of the 2000 IEEE International Symposium on Intelligent Control. Held jointly with the 8th IEEE Mediterranean Conference on Control and Automation (Cat. No.00CH37147), 2000
A new view on discrete event dynamic systems (DEDS) modelling and control synthesis is presented. To be more effective at the control synthesis Petri nets (PN), frequently used for DEDS modelling, are replaced here by a form of corresponding oriented graphs (OG). The adjacency matrix of such a graph is succesfully utilized in the DEDS control synthesis procedure. The state reachability tree in both the straight-lined system dynamics development (from an initial state to a prescribed terminal one) and the backtracking one (from the terminal state to the initial one) are generated. To solve the DEDS control synthesis problem a suitable combination both of these kinds of the model dynamics development is utilized. Namely, the intersection both of the state reachability trees yields all feasible trajectories of the system dynamics development, i.e. all realizable possibilities how to reach the prescribed terminal state from the given initial one, are automatically found. To choose the most suitable solution of the control synthesis problem rule-based knowledge about the control task specifications is utilized.
Petri Nets-Based Computer Aided Synthesis of Control Systems for Discrete Events Dynamic Systems
IFAC Proceedings Volumes, 1991
An idea of utilizing the Petri nets-based analytical system approach to modelling the discrete event dynamic systems and its application to the automation of their control systems synthes i s is presented and elaborated in this paper. Not to be dependent on partial features of a problem to be dealt with a general abstract discrete dynamic system is built by means of the so called bounded ordinary Petri nets to model the mentioned types of systems to be controlled. In attempting to treat problems of the computer aided synthesis of their contro l systems by means of a uniform analytical technique, we find that the automatic step-by-step analysis of the model gives us the expected procedure. This procedure can serve as a kernel of a decision support algorithm. It is developed to improve and generalize the previous author's (1988) procedure by means of utilizing the main principle of the automatic reasoning presented and elaborated in recent author's works (1990). Its applicability is illustrated on a simple example of the automatic robot assembly.
A Survey of Petri Net Methods for Controlled Discrete Event Systems
Discrete Event Dynamic Systems, 1997
This paper surveys recent research on the application of Petri net models to the analysis and synthesis of controllers for discrete event systems. Petri nets have been used extensively in applications such as automated manufacturing, and there exists a large body of tools for qualitative and quantitative analysis of Petri nets. The goal of Petri net research in discrete event systems is to exploit the structural properties of Petri net models in computationally efficient algorithms for computing controls. We present an overview of the various models and problems formulated in the literature focusing on two particular models, the controlled Petri nets and the labeled nets. We describe two basic approaches for controller synthesis, based on state feedback and event feedback. We also discuss two efficient techniques for the on-line computation of the control law, namely the linear integer programming approach which takes advantage of the linear structure of the Petri net state transiti...
Regulation problem in discrete event systems using interpreted Petri nets
SMC 2000 Conference Proceedings. 2000 IEEE International Conference on Systems, Man and Cybernetics. 'Cybernetics Evolving to Systems, Humans, Organizations, and their Complex Interactions' (Cat. No.00CH37166)
This paper presents a new approach to control DES modeled by interpreted Petri nets (IPN). The controller is obtained mainly using structural information of the system; it is devoted to track the output of another IPN called the reference model. This control approach is based on the regulation problem from continuos systems control. In this paper, it will be shown that if the controller exists such that solves the regulation problem, then the system and the reference model fulfills some conditions. Using both, the system and the reference model state, a state feedback control law can be implemented avoiding a feedback trajectory.
Step state-feedback supervisory control of Discrete Event Systems using Interpreted Petri Nets
2008
This paper deals with supervisory control of discrete event systems (DES) modeled by interpreted Petri nets (IPN). In the approach herein proposed, both, the specification and the system model are described by IPN, however, the specification describes a state subset that the specification must reach. It also captures the order in which these states must be reached. Based on this framework, this paper presents a method to compute the system firing transition sequence in order to confine the system model into the specification behavior. Although this problem is NP-complete, the proposed solution exploits the structural information of both IPN (system and specification) to compute Parikh vectors of system firing sequences; one vector per each transition of the specification. These Parikh vectors are processed in order to obtain controllable fireable transition sequences. Thus a divide and conquer technique is used, where the NP-complete problem divided into k small size problems (where k is the number of specification transitions), reducing the computational time of proposed algorithms. Moreover, the technique herein presented is suitable for distributed and hierarchical control. All algorithms herein purposed have being implemented in MAPLE.
Control synthesis approach for DES modelled by Petri Nets
This paper presents a control synthesis approach for discrete event systems modelled by ordinary Petri Nets (PN) to solve a forbidden state problem. The PN herein considered are transitions controllable and contain measurable and non measurable transitions. The proposed PN controller is synthesised using the influence paths of the forbidden transitions. The latter are deduced from the PN reachability graph. The designed PN controller is maximally permissive because it prevents the occurrence of forbidden markings and guarantees exactly the desired behaviours. The proposed approach is illustrated by an example.
The International Journal of Advanced Manufacturing Technology, 1998
As automated manufacturing systems become more complex, the need for an effective design tool to produce both highlevel discrete event control systems (DECS) and low-level implementations becomes more important. Petri nets represent the most effective method for both the design and implementation of DECSs. In this paper, automation Petri nets (APN) are introduced to provide a new method for the design and implementation of DECSs. The APN is particularly well suited to multiproduct systems and provides a more effective solution than Grafcet in this context. Since ordinary Petri nets do not deal with sensors and actuators of DECSs, the Petri net concepts are extended, by including actions and sensor readings as formal structures within the APN. Moreover, enabling and inhibitor arcs, which can enable or disable transitions through the use of leading-edge, falling-edge and level of markings, are also introduced. In this paper, the methodology is explained by considering a fundamental APN structure. The conversion of APNs into the IECtt31-3 ladder diagrams (LD) for implementation on a PLC is also explained by using the token passing logic (TPL) concept. Finall); an illustrative example of how APNs can be applied to a discrete manufacturing problem is described in detail.
The International Journal of Advanced Manufacturing Technology, 2003
This paper describes a method for constructing a Petri-net-based controller for a discrete event system (DES) modelled by a Petri net. Assuming that an uncontrolled Petri net model of the DES and a set of forbidden state specifications are given, feedback control elements, i.e. a set of places and related transitions, with initial marking, are computed using the theory of egions, which is a formal synthesis technique for deriving Petri nets from automaton-based models. When feedback control elements are added to the uncontrolled Petri net model, the controlled (closed-loop) Petri net model of the system is obtained. The controlled Petri net model obtained is maximally permissive while guaranteeing that forbidden states do not occur. The proposed method is computationally efficient and does not suffer from the state explosion problem. Two examples are provided to show the applicability of the proposed method.