scholarly journals Deadlock Prevention Policy with Behavioral Optimality or Suboptimality Achieved by the Redundancy Identification of Constraints and the Rearrangement of Monitors

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Liang Hong ◽  
YiFan Hou ◽  
JunFeng Jing ◽  
AnRong Wang ◽  
Dmitry A. Litvin
Keyword(s):  
Flexible Manufacturing ◽  
Manufacturing Systems ◽  
Mixed Integer ◽  
Deadlock Prevention ◽  
Second Phase ◽  
Deadlock Detection ◽  
Prevention Policy ◽  
Prevention Method ◽  
Two Phases ◽  
Redundancy Identification

This work develops an iterative deadlock prevention method for a special class of Petri nets that can well model a variety of flexible manufacturing systems. A deadlock detection technique, called mixed integer programming (MIP), is used to find a strict minimal siphon (SMS) in a plant model without a complete enumeration of siphons. The policy consists of two phases. At the first phase, SMSs are obtained by MIP technique iteratively and monitors are added to the complementary sets of the SMSs. For the possible existence of new siphons generated after the first phase, we add monitors with their output arcs first pointed to source transitions at the second phase to avoid new siphons generating and then rearrange the output arcs step by step on condition that liveness is preserved. In addition, an algorithm is proposed to remove the redundant constraints of the MIP problem in this paper. The policy improves the behavioral permissiveness of the resulting net and greatly enhances the structural simplicity of the supervisor. Theoretical analysis and experimental results verify the effectiveness of the proposed method.

A Channelized Deadlock Prevention Policy for Flexible Manufacturing Systems Using Petri Net Models

2011 ◽  
Vol 284-286 ◽  
pp. 1498-1501
Author(s):  
Yi Sheng Huang ◽  
Ter Chan Row
Keyword(s):  
Petri Net ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Control Policy ◽  
Deadlock Avoidance ◽  
Deadlock Prevention ◽  
Deadlock Detection ◽  
Prevention Policy ◽  
Maximal Permissiveness

Deadlock prevention, deadlock detection and deadlock avoidance strategies are used to solve the deadlock problems of flexible manufacturing systems (FMSs). The conventional prevention policies were always attempt to prevent the system entering the deadlocked situation by using a few control places. On can know that one prohibits the deadlocked markings, some dead markings will be sacrificed. Therefore, the reachability states will become less than the initial net. However, our goal is to preserve all the reachability states of the initial net. Under our control policy, the deadlocks or deadlock zone will be channelized to live markings such that all the dead markings in reachability states will be conserved. Finally, an example is performed and can obtain the maximal permissiveness of a Petri net model. The other examples are all getting the same result. To our knowledge, this is the first work that employs the channelized method to prevent the deadlock problem for FMSs.

Deadlock Control in Generalized Petri Nets

2013 ◽  
pp. 343-366 ◽  
Author(s):  
Mi Zhao ◽  
Yifan Hou
Keyword(s):  
Computational Complexity ◽  
Petri Nets ◽  
Flexible Manufacturing ◽  
Manufacturing Systems ◽  
Structural Complexity ◽  
Mixed Integer ◽  
Future Research ◽  
Deadlock Prevention ◽  
Prevention Policy ◽  
Detection Approach

This chapter proposes a number of deadlock prevention polices for a class of generalized Petri nets, namely G-systems, which is usually considered to be the most generalized Petri nets that can model Flexible Manufacturing Systems (FMSs) with machining, assembly, and disassembly operations. First, a deadlock prevention policy based on elementary siphons theory is presented, which indicates that structural complexity and behavioral permissiveness can be improved effectively. In order to reduce the computational complexity, a Mixed Integer Programming (MIP)-based deadlock detection approach is proposed, then two deadlock control polices combined with MIP method are introduced. Finally, comparison among deadlock prevention policies reported in this chapter is done in terms of structural complexity, behavioral permissiveness, and computational complexity of the resulting supervisor through a typical case study. Importantly, future research directions related to this area are presented at the end of this chapter.

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.

Petri Net Channelized-Based Deadlock Prevention Policy for Flexible Manufacturing Systems

2011 ◽  
Vol 317-319 ◽  
pp. 552-555
Author(s):  
Yi Sheng Huang ◽  
Ter Chan Row
Keyword(s):  
Control System ◽  
Petri Net ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Control Policy ◽  
Original Model ◽  
Deadlock Prevention ◽  
Prevention Policy ◽  
Maximal Permissiveness

Petri nets are employed to model flexible manufacturing systems (FMSs). However, the system deadlocked are possible happened. The conventional deadlock prevention policies are always to forbid the system entering the deadlock by using the control places. To obtain a live system, some dead markings must be sacrificed in the traditional policies. Therefore, the original reachability states of the original model can not be conserved. However, this paper is able to maintain all the reachability states of the original net and guaranty the control system live. Under our control policy, all number of reachability states of the original net will be preserved. Finally, two examples are performed that can reach the maximal permissiveness for FMSs using Petri net models (PNMs).

scholarly journals Supervisor Reconfiguration for Deadlock Prevention by Resources Reallocation

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Miao Liu ◽  
Shouguang Wang ◽  
Zhiwu Li
Keyword(s):  
Efficient Method ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Deadlock Prevention ◽  
Prevention Policy ◽  
Computationally Efficient ◽  
Controlled System ◽  
Plant Model ◽  
And Control

Analysis and control of deadlocks play an important role in the design and operation of automated flexible manufacturing systems (FMSs). In FMS, deadlocks are highly undesirable situations, which always cause unnecessary cost. The design problem of an optimal supervisor is in general NP-hard. A computationally efficient method often ends up with a suboptimal one. This paper develops a deadlock prevention policy based on resources reallocation and supervisor reconfiguration. First, given a plant model, we reallocate the marking of each resource place to be one, obtaining a net model whose reachable states are much less than that of the original one. In this case, we find a controlled system for it by using the theory of regions. Next, the markings of the resource places in the controlled system are restored to their original ones. Without changing the structure of the obtained controlled system, we compute the markings of the monitors gradually, which can be realized by two algorithms proposed in this paper. Finally, we decide a marking for each monitor such that it makes the controlled system live with nearly optimal permissive behavior. Two FMS examples are used to illustrate the application of the proposed method and show its superior efficiency.

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