Computationally Improved Optimal Deadlock Prevention Policy for Linear Programming Problems of Flexible Manufacturing Systems

2013 ◽  
Author(s):  
Yen-Liang Pan ◽  
Mu-Der Jenga ◽  
Sheng-Luen Chungb ◽  
Yu-Xin Guoa
Keyword(s):  
Linear Programming ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Deadlock Prevention ◽  
Prevention Policy ◽  
Linear Programming Problems

scholarly journals Computationally Improved Optimal Control Methodology for Linear Programming Problems of Flexible Manufacturing Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Yen-Liang Pan ◽  
Yi-Sheng Huang ◽  
Yi-Shun Weng ◽  
Weimin Wu ◽  
MuDer Jeng
Keyword(s):  
Linear Programming ◽  
Petri Net ◽  
Flexible Manufacturing ◽  
Manufacturing Systems ◽  
Computational Cost ◽  
Deadlock Prevention ◽  
Prevention Policy ◽  
Linear Programming Problems ◽  
Control Methodology ◽  
State Separation

Deadlock prevention policies are used to solve the deadlock problems of FMSs. It is well known that the theory of regions is the efficient method for obtaining optimal (i.e., maximally permissive) controllers. All legal and live maximal behaviors of Petri net models can be preserved by using marking/transition-separation instances (MTSIs) or event-state-separation-problem (ESSP) methods. However, they encountered great difficulties in solving all sets of inequalities that is an extremely time consuming problem. Moreover, the number of linear programming problems (LPPs) of legal markings is also exponential with net size when a plant net grows exponentially. This paper proposes a novel methodology to reduce the number of MTSIs/ESSPs and LPPs. In this paper, we used the well-known reduction approach Murata (1989) to simply the construct of system such that the problem of LPPs can then be reduced. Additionally, critical ones of crucial marking/transition-separation instances (COCMTSI) are developed and used in our deadlock prevention policy that allows designers to employ few MTSIs to deal with deadlocks. Experimental results indicate that the computational cost can be reduced. To our knowledge, this deadlock prevention policy is the most efficient policy to obtain maximal permissive behavior of Petri net models than past approaches.

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.

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.

Distributed Computation of Liveness-Enforcing Supervisory Control of Flexible Manufacturing Systems

2017 ◽  
Vol 16 (01) ◽  
pp. 1-15 ◽  
Author(s):  
Fatemeh Jafarinejad ◽  
Ali A. Pouyan
Keyword(s):  
Supervisory Control ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Large Scale ◽  
Deadlock Prevention ◽  
Prevention Policy ◽  
Synthesis Procedure ◽  
Essential Set ◽  
Time And Space Complexity

This paper presents a modular deadlock prevention policy for large-scale flexible manufacturing systems. It can find maximally permissive liveness-enforcing supervisory control in an efficient computational complexity manner. A vector covering approach is used to minimize essential set of legal markings and first-met bad markings. Providing that modules of system interact using choice, we will prove that monitor-based supervisory control methods can be applied distributedly. Then, choice operator of Petri net will be used to synthesis subsystems. Even if such assumption limits the application of modular monitor-based supervisory control, the proposed results constitute a primary step towards a synthesis procedure that overcomes time and space complexity of monitor-based deadlock prevention policies.

Sign in / Sign up

Export Citation Format

Share Document