Elementary-Siphon-Based Control Policy for Flexible Manufacturing Systems with Partial Observability and Controllability of Transitions

2014 ◽  
Vol 17 (1) ◽  
pp. 327-342 ◽  
Author(s):  
Meng Qin ◽  
ZhiWu Li ◽  
Abdulrahman M. Al-Ahmari
Keyword(s):  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Control Policy ◽  
Partial Observability ◽  
Elementary Siphon

Design of Optimized Petri Net Supervisors for Flexible Manufacture Systems Based on Elementary Siphons

2013 ◽  
pp. 322-342
Author(s):  
Mingming Yan
Keyword(s):  
Petri Net ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Deadlock Prevention ◽  
Excellent Performance ◽  
Plant Model ◽  
Elementary Siphon ◽  
Flexible Manufacture ◽  
Major Target

This chapter focuses on the deadlock prevention problems in Flexible Manufacturing Systems (FMS), and the major target is to design more excellent controllers that lead to a more permissive supervisor by adding a smaller number of monitors and arcs than the existing ones in the literature for the design of liveness-enforcing Petri net supervisors. The authors distinguish siphons in a Petri net model by elementary and dependent ones. For each elementary siphon, a monitor is added to the plant model such that it is invariant-controlled without generating emptiable control-induced siphons, and the controllability of a dependent siphon is ensured by changing the control depth variables of its related elementary siphons. Hence, a structurally simple Petri net supervisor is achieved. Based on the previous work, this chapter explores two optimized deadlock prevention approaches based on elementary siphons that can achieve the same control purpose and have more excellent performance.

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).

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 Maximally Permissive Nonblocking Control of Flexible Manufacturing Systems

2013 ◽  
pp. 36-60
Author(s):  
Renyuan Zhang ◽  
Yongmei Gan ◽  
W. M. Wonham ◽  
Zhaoan Wang
Keyword(s):  
Distributed Control ◽  
Petri Net ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Control Policy ◽  
Recent Theory ◽  
Automatic Guided Vehicle ◽  
Resource Allocation Systems ◽  
Production Cell

In recent years, a great deal of research has been focused on preventing deadlock in Flexible Manufacturing Systems. Policies based largely on Petri net models have been presented in the literature. Recently, a quite different approach has been developed based on supervisory control theory, and it has been adapted to solve the nonblocking maximally permissive control problem in various resource allocation systems, such as an Automatic Guided Vehicle system and a Production Cell. In this chapter, the authors obtain the corresponding control policy for a Flexible Manufacturing System, and from it derive an equivalent distributed control using the recent theory of supervisor localization.

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.

A Computationally Improved Control Policy for FMS Using Crucial Marking/Transition-Separation Instances

2013 ◽  
pp. 61-82
Author(s):  
Yi-Sheng Huang ◽  
Yen-Liang Pan
Keyword(s):  
Petri Net ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Control Policy ◽  
Deadlock Avoidance ◽  
Deadlock Prevention ◽  
Deadlock Detection ◽  
Optimal Controllers ◽  
Unique Method

Deadlock prevention, deadlock detection, and deadlock avoidance strategies are used to solve the deadlock problems of Flexible Manufacturing Systems (FMS). The theory of regions has been recognized as the unique method for obtaining maximally permissive controllers in the existing literature. All legal and live maximal behavior of a Petri net model can be preserved by using a Marking/Transition-Separation Instance (MTSI). However, obtaining all sets of MTSIs is an extremely time consuming problem. This work proposes Crucial Marking/Transition-Separation Instances (CMTSIs) that allow designers to employ few MTSIs to deal with deadlocks. The advantage of the proposed policy is that a maximally permissive controller can be obtained with drastically reduced computation. Experimental results, by varying the markings of given net structures, indicate that it is the most efficient policy to obtain optimal controllers among existing methods based on the theory of regions.

scholarly journals One Computational Innovation Transition-Based Recovery Policy for Flexible Manufacturing Systems Using Petri nets

2020 ◽  
Vol 10 (7) ◽  
pp. 2332 ◽  
Author(s):  
Yen-Liang Pan
Keyword(s):  
Petri Nets ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Control Policy ◽  
Deadlock Prevention ◽  
Three Dimension ◽  
Factory Production ◽  
Almost All ◽  
Industrial Revolutions

In the third and fourth industrial revolutions, smart or artificial intelligence flexible manufacturing systems (FMS) seem to be the key machine equipment for capacity of factory production. However, deadlocks could hence appear due to resources competition between robots. Therefore, how to prevent deadlocks of FMS occurring is a very important and hot issue. Based on Petri nets (PN) theory, in existing literature almost all research adopts control places as their deadlock prevention mean. However, under this strategy the real optimal reachable markings are not achieved even if they claimed that their control policy is maximally permissive. Accordingly, in this paper, the author propose one novel transition-based control policy to solve the deadlock problem of FMS. The proposed control policy could also be viewed as deadlock recovery since it can recover all initial deadlock and quasi-deadlock markings. Furthermore, control transitions can be calculated and obtained once the proposed three-dimension matrix, called generating and comparing aiding matrix (GCAM) in this paper, is built. Finally, an iteration method is used until all deadlock markings become live ones. Experimental results reveal that our control policy seems still the best one among all existing methods in the literature regardless of whether these methods belong to places or transitions based.

scholarly journals Enhancement of Selective Siphon Control Method for Deadlock Prevention in FMSs

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Yen-Liang Pan ◽  
Cheng-Fu Yang ◽  
Mu-Der Jeng
Keyword(s):  
Computational Efficiency ◽  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Control Method ◽  
Control Policy ◽  
Experimental Results ◽  
Deadlock Prevention ◽  
Exact Number ◽  
Sequential Processes

One novel control policy named selective siphon control policy is proposed to solve for deadlock problems of flexible manufacturing systems (FMSs). The new policy not only solves the deadlock problem successfully but also obtains maximally permissive controllers. According to our awareness, the policy is the first one to achieve the goal of obtaining maximally permissive controllers for all S3PR (one system of simple sequential processes with resources, S3PR) models in existing literature. However, one main problem is still needed to solve in their algorithm. The problem is that the proposed policy cannot check the exact number of maximally permissive states of a deadlock net in advance. After all iterating steps, the final maximally permissive states can then be known. Additionally, all legal markings are still to be checked again and again until all critical markings vanished. In this paper, one computationally improved methodology is proposed to solve the two problems. According to the experimental results, the computational efficiency can be enhanced based on the proposed methodology in this paper.

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