Petri Net Supervisory Method for Linear Constraints and its Applications to Flexible Manufacturing Systems

2013 ◽  
pp. 20-35
Author(s):  
Jiliang Luo
Keyword(s):  
Petri Nets ◽  
Petri Net ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Manufacturing System ◽  
Flexible Manufacturing System ◽  
Linear Constraints ◽  
Supervisor Synthesis ◽  
Synthesis Procedure

An algorithm is proposed to equivalently transform original linear constraints on Petri nets, where the uncontrollable subnets are forward-concurrent free nets, into admissible ones. Consequently, this algorithm can be used to design both efficient and optimal supervisors for enforcing linear constraints on Petri nets since the problem on how to enforce admissible constraints has been well solved. Further, the supervisor synthesis procedure is presented using this algorithm. Lastly, it is illustrated by an example where an optimal supervisor is designed for a flexible manufacturing system.

scholarly journals Optimal enforcement of liveness to flexible manufacturing systems modeled with Petri nets via transition-based controllers

2018 ◽  
Vol 10 (1) ◽  
pp. 168781401775070 ◽  
Author(s):  
Muhammad Bashir ◽  
Ding Liu ◽  
Murat Uzam ◽  
Naiqi Wu ◽  
Abdulrahman Al-Ahmari ◽  
...  
Keyword(s):  
Petri Nets ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Manufacturing System ◽  
Flexible Manufacturing System ◽  
Control Technique ◽  
Controlled System ◽  
High Productivity ◽  
Full Utilization

This article reports a transition-based control technique to prevent deadlocks for flexible manufacturing systems that can be modeled with a generalized class of Petri nets. The proposed method utilizes the structural properties of the Petri net model to avoid the computation of its reachability graph which in general leads to the state explosion problem. Three algorithms are developed. The first and second algorithms aim to compute first-met and n-met uncontrolled transitions, respectively, in an iterative manner until all the n-met uncontrolled transitions are found in the plant net model. The third algorithm is used to design n-transition controllers iteratively. The iteration terminates when all the transitions in the set of uncontrolled transitions are processed. The addition of the n-transition controllers to the plant net model is to make the n-met uncontrolled transitions controlled. The transition controllers are capable of enforcing liveness to the plant net model with all its reachable markings being retained in the controlled system, which ensures the full utilization of resources and provides the high productivity of a flexible manufacturing system.

Petri Net Based Deadlock Prevention Approach for Flexible Manufacturing Systems

2011 ◽  
pp. 416-433 ◽  
Author(s):  
Chunfu Zhong ◽  
Zhiwu Li
Keyword(s):  
Petri Nets ◽  
Petri Net ◽  
Flexible Manufacturing ◽  
Mixed Integer Linear Programming ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Iteration Step ◽  
Mixed Integer ◽  
Deadlock Prevention ◽  
Prevention Approach

In flexible manufacturing systems, deadlocks usually occur due to the limited resources. To cope with deadlock problems, Petri nets are widely used to model these systems. This chapter focuses on deadlock prevention for flexible manufacturing systems that are modeled with S4R nets, a subclass of generalized Petri nets. The analysis of S4R leads us to derive an iterative deadlock prevention approach. At each iteration step, a non-max-controlled siphon is derived by solving a mixed integer linear programming. A monitor is constructed for the siphon such that it is max-controlled. Finally, a liveness-enforcing Petri net supervisor can be derived without enumerating all the strict minimal siphons.

Extraction of elementary siphons in a class of generalized Petri nets using graph theory

2014 ◽  
Vol 31 (2) ◽  
pp. 331-352 ◽  
Author(s):  
YiFan Hou ◽  
ZhiWu Li ◽  
Mi Zhao ◽  
Ding Liu
Keyword(s):  
Graph Theory ◽  
Petri Nets ◽  
Petri Net ◽  
Flexible Manufacturing ◽  
Design Methodology ◽  
Manufacturing System ◽  
Flexible Manufacturing System ◽  
Structural Complexity ◽  
Compact Set ◽  
Content Type

Purpose – Siphon-based deadlock control in a flexible manufacturing system (FMS) suffers from the problems of computational and structural complexity since the number of siphons grows exponentially with respect to the size of its Petri net model. In order to reduce structural complexity of a supervisor, a set of elementary siphons derived from all strict minimal siphons (SMS) is explicitly controlled. The purpose of this paper is through fully investigating the structure of a class of generalized Petri nets, WS3PR, to compute all SMS and a compact set of elementary siphons. Design/methodology/approach – Based on graph theory, the concepts of initial resource weighted digraphs and restricted subgraphs are proposed. Moreover, the concept of augmented siphons is proposed to extend the application of elementary siphons theory for WS3PR. Consequently, the set of elementary siphons obtained by the proposed method is more compact and well suits for WS3PR. Findings – In order to demonstrate the proposed method, an FMS example is presented. All SMS and elementary siphons can be derived from initial resource weighted digraphs. Compared with those obtained by the method in Li and Zhou, the presented method is more effective to design a structural simple liveness-enforcing supervisor for WS3PR. Originality/value – This work presents an effective method of computing SMS and elementary siphons for WS3PR. Monitors are added for the elementary siphons only, and the controllability of every dependent siphon is ensured by properly supervising its elementary ones. A same set of elementary siphons can be admitted by different WS3PR with isomorphic structures.

scholarly journals Global Supervisory Structure for Decentralized Systems of Flexible Manufacturing Systems Using Petri Nets

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 595 ◽  
Author(s):  
Muhammad Bashir ◽  
Liang Hong
Keyword(s):  
Computational Complexity ◽  
Petri Nets ◽  
Petri Net ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Structural Complexity ◽  
Decentralized Systems ◽  
The Cost ◽  
Global Controller

Decentralized supervisory structure has drawn much attention in recent years to address the computational complexity in designing supervisory structures for large Petri net model. Many studies are reported in the paradigm of automata while few can be found in the Petri net paradigm. The decentralized supervisory structure can address the computational complexity, but it adds the structural complexity of supervisory structure. This paper proposed a new method of designing a global controller for decentralized systems of a large Petri net model for flexible manufacturing systems. The proposed method can both reduce the computational complexity by decomposition of large Petri net models into several subnets and structural complexity by designing a global supervisory structure that can greatly reduce the cost at the implementation stage. Two efficient algorithms are developed in the proposed method. Algorithm 1 is used to compute decentralized working zones from the given Petri net model for flexible manufacturing systems. Algorithm 2 is used to compute the global controller that enforces the liveness to the decentralized working zones. The ring assembling method is used to reconnect and controlled the working zones via a global controller. The proposed method can be applied to large Petri nets size and, in general, it has less computational and structural complexity. Experimental examples are presented to explore the applicability of the proposed method.

Flexible Manufacturing System for Drawingless Manufacturing

2013 ◽  
Vol 581 ◽  
pp. 527-532
Author(s):  
Peter Košťál ◽  
Daynier Rolando Delgado Sobrino
Keyword(s):  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Manufacturing System ◽  
Flexible Manufacturing System ◽  
3D Model ◽  
Fast Reaction ◽  
Technological Data ◽  
Geometrical Data ◽  
Production Conditions

Flexible Manufacturing Systems provide a fast reaction possibility to the changes in production conditions. As production conditions change, other changes in the final product like changes of the product variants, or other unpredictable events may be also expected. For achieving a quick responsibility of production, it is necessary to leave the traditional form of production process planning. Nowadays most of the products are designed by using the CAx software. The product design 3D model contains not only the geometrical data of product, but may contain a part of the process plan and technological data as well.

Deadlock Prevention for Automated Manufacturing Systems with Uncontrollable and Unobservable Transitions

2013 ◽  
pp. 367-387
Author(s):  
Meng Qin
Keyword(s):  
Petri Nets ◽  
Petri Net ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Deadlock Prevention ◽  
Sufficient Condition ◽  
Prevention Policy ◽  
Automated Manufacturing Systems ◽  
Partial Observability

Many deadlock prevention policies on the basis of Petri nets dealing with deadlock problems in flexible manufacturing systems exist. However, most of them do not consider uncontrollable and unobservable transitions. This chapter solves deadlock problems in Petri nets with uncontrollable and unobservable transitions. A sufficient condition is developed to decide whether an existing deadlock prevention policy is still applicable in a Petri net with uncontrollable and unobservable transitions, when the policy itself is developed under the assumption that all the transitions are controllable and observable. Moreover, the author develops a deadlock prevention policy to design liveness-enforcing supervisors for a class of Petri nets with partial observability and controllability of transitions. Furthermore, a sufficient condition to decide the existence of a monitor to enforce a liveness constraint is developed.

The application of a flexible tooling system in a flexible manufacturing system

Robotica ◽  
1985 ◽  
Vol 3 (4) ◽  
pp. 221-228 ◽  
Author(s):  
Norman Carter
Keyword(s):  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Manufacturing System ◽  
Flexible Manufacturing System ◽  
Management Systems ◽  
Tool Management ◽  
A Value ◽  
Tooling System ◽  
Machine Utilisation

SUMMARYThe introduction of Flexible Manufacturing Systems, Cell Technology, and Automated Machining Techniques with the related reduction in manning levels has resulted in the development of tooling systems, tool management systems, and, independent tool magazines to service TURNING MACHINES where a high number of tools are required to cover one shift or unmanned operation.Actual cutting time (production time) represents a value between 5% and 20% of average machine utilisation time, and developments in cutting materials and geometries have largely exhausted rationalisation possibilities in this area.

scholarly journals One Novel and Optimal Deadlock Recovery Policy for Flexible Manufacturing Systems Using Iterative Control Transitions Strategy

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ter-Chan Row ◽  
Wei-Ming Syu ◽  
Yen-Liang Pan ◽  
Ching-Cheng Wang
Keyword(s):  
Petri Nets ◽  
Petri Net ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Experimental Results ◽  
Reachability Graph ◽  
Sequential Processes ◽  
Iterative Control

This paper focuses on solving deadlock problems of flexible manufacturing systems (FMS) based on Petri nets theory. Precisely, one novel control transition technology is developed to solve FMS deadlock problem. This new proposed technology can not only identify the maximal saturated tokens of idle places in Petri net model (PNM) but also further reserve all original reachable markings whatever they are legal or illegal ones. In other words, once the saturated number of tokens in idle places is identified, the maximal markings of system reachability graph can then be checked. Two classical S3PR (the Systems of Simple Sequential Processes with Resources) examples are used to illustrate the proposed technology. Experimental results indicate that the proposed algorithm of control transition technology seems to be the best one among all existing algorithms.

scholarly journals An Efficient Siphon-Based Deadlock Prevention Policy for a Class of Generalized Petri Nets

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
YiFan Hou ◽  
Mi Zhao ◽  
Ding Liu ◽  
Liang Hong
Keyword(s):  
Petri Nets ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Synthesis Method ◽  
Deadlock Avoidance ◽  
Deadlock Prevention ◽  
Prevention Policy ◽  
Supervisor Synthesis ◽  
Resource Allocation Systems

We propose a new deadlock prevention policy for an important class of resource allocation systems (RASs) that appear in the modeling of flexible manufacturing systems (FMSs). The model of this class in terms of generalized Petri nets is, namely, S4PR. On the basis of recent structural analysis results related to the elementary siphons in generalized Petri nets on one hand and an efficient deadlock avoidance policy proposed for the class of conjunctive/disjunctive (C/D) RASs on the other hand, we show how one can generate monitors to be added to a net system such that all its strict minimal siphons aremax′-controlled and no insufficiently marked siphon is generated. Thereby, a new, simple, and more permissive liveness-enforcing supervisor synthesis method for S4PR is established.

Optimal enforcement of liveness for decentralized systems of flexible manufacturing systems using Petri nets

2020 ◽  
Vol 42 (12) ◽  
pp. 2206-2220
Author(s):  
Muhammad Bashir
Keyword(s):  
Computational Complexity ◽  
Petri Nets ◽  
Petri Net ◽  
Supervisory Control ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Common Elements ◽  
Decentralized Controllers ◽  
The Given

The decentralized supervisory structure has drawn much attention in recent years. Many studies are reported in the paradigm of automata while few can be found in the Petri net model. This paper proposes a new method for decentralized supervisory control using the Petri net paradigm. Two efficient Algorithms are developed in the proposed method. Algorithm 1 is used to compute decentralized working zones from the given LS3PR Petri net model for flexible manufacturing systems. Algorithm 2 is used to compute the decentralized controllers that enforced liveness to the decentralized working zones. The sequential assembling is used to reconnect and controlled the working zones via decentralized controllers. The decentralized controller is added to the decentralized working zones that have common elements, that is, common transitions. The proposed method has the following advantages: (i) it can be applied to a complex Petri net model for flexible manufacturing systems, (ii) the proposed methods has less computational complexity when compared with the previous methods, (iii) the proposed method can obtain a minimal number of decentralized controllers that enforce liveness of the uncontrolled Petri net model. Experimental examples are presented to explore the applicability of the proposed methods.

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