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.

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.

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.

scholarly journals Liveness characteristic analysis of a class of Petri nets

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878148
Author(s):  
Miao Liu ◽  
Zhou He
Keyword(s):  
Computational Complexity ◽  
Petri Nets ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Effective Algorithm ◽  
Finite Capacity ◽  
Characteristic Analysis ◽  
Control Actions ◽  
Sequential Processes

Petri nets are an effective tool for analyzing and modeling the dynamic behavior of flexible manufacturing systems. Finite capacity systems of simple sequential processes with resources are an important subclass of Petri nets, for which this article gives a liveness characteristic analysis. First, an effective algorithm for deciding the liveness of finite capacity systems of simple sequential processes with resources is developed by analyzing the relation between the structural properties of resource subnets and the strict minimal siphons. Then, a liveness condition of finite capacity systems of simple sequential processes with resources is accordingly established. Based on the proposed liveness condition, an algorithm for configuring an initial marking for a finite capacity systems of simple sequential processes with resources is given, and therefore, a live finite capacity systems of simple sequential processes with resources net with a configured initial marking can be obtained, which avoids the siphon enumerations and the addition of any control actions. It is shown that the computational complexity of both the developed liveness deciding and the initial marking configuration algorithms is polynomial. Examples are finally provided to illustrate the mentioned results.

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.

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 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.

An Efficient Deadlock Avoidance Policy for FMS Using ROPN

2014 ◽  
Vol 998-999 ◽  
pp. 751-754
Author(s):  
Yu Ming Zhao ◽  
Xiang Ju Chai ◽  
Li Zhen Zhao
Keyword(s):  
Petri Nets ◽  
Petri Net ◽  
Control Strategy ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Control Policy ◽  
Deadlock Avoidance ◽  
Concurrent Execution ◽  
Better Than

This article shows a composed method for modeling the concurrent execution of working processes in flexible manufacturing systems (FMS) by a special class of Petri nets named Resource Oriented Petri nets (ROPN). Essentially, the type of net comes from the availability of system resources. The analysis of ROPN is used to characterize deadlock situations in terms of full markings for certain structure named PPC. For the sake of preventing the system from deadlocks, a policy is proposed based on a series of restrictions for resource allocation, without considering the presence of unmarked siphons in Process Oriented Petri net (POPN). Finally, a control strategy of deadlock avoidance is designed for ROPN, which is better than other control policy.

Petri Net Based Deadlock Prevention Approach for Flexible Manufacturing Systems

2012 ◽  
pp. 445-463
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.

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