基于Petri网的柔性制造系统的网简化技术研究

发布时间：2018-04-12 08:42

本文选题：冗余控制库所 + 柔性制造系统　；参考：《浙江工商大学》2012年硕士论文

【摘要】：柔性制造系统中共享资源的分配不当是死锁产生的主要原因。一旦出现死锁,系统生产就会出现停顿,从而导致昂贵设备的生产率低下,造成生产企业的经济损失,有时候甚至会造成灾难性的后果。有效处理系统的死锁问题是保证制造系统获得高生产率的前提条件,因此,寻找有效的方法来预防和控制柔性制造系统中的死锁已经成为近年来研究的热点。 Petri网是一种重要的建模工具,能够描述资源共享、互斥、并发和冲突等,而且在计算方面也表现出了优越的性能,相比于自动机等建模工具具有明显的优势,因而成为研究柔性制造系统死锁问题的主要建模工具。S3PR网是柔性制造系统Petri网模型的一个重要子类,也是大多数学者研究柔性制造系统死锁问题通常采用的模型。本文的研究工作基于S3PR网,主要集中在降低活性Petri网控制器的结构复杂性、提高其行为许可性,同时降低求解活性控制器的计算复杂性。本文的主要研究成果如下： 1.现有的死锁控制策略通常是基于信标来添加控制库所,最终得到活性的控制器。本文通过分析基于信标的死锁控制策略中添加的控制库所的特点,提出了一种基于信标资源排序的控制库所冗余性检测方法。现有的死锁控制策略得到的活性Petri网控制器中往往含有冗余控制库所,而本文提出的方法的优点在于能够剔除最大数量的冗余控制库所,且与检测控制库所冗余性的顺序无关,最终得到的活性控制器具有较简单的结构和较多的许可行为。 2.本文提出了一种基于必需控制库所设计优化控制器的的方法。在一般情况下,此法得到的活性控制器在行为许可性和结构复杂性方面有较好的性能。特别是当输入的活性控制器中含有多组必需控制库所的时候,此法得到的控制器在行为许可性和结构复杂性方面的优势更加明显。最优控制器的求解一直是设计活性Petri网控制器的研究热点。文中的两个柔性制造系统实例表明本文方法得到的优化控制器能以较简单的结构得到接近最优的行为许可性。最后,在总结全文的基础上,对基于Petri网的柔性制造系统活性控制器简化技术的未来研究工作进行了展望。
[Abstract]:Improper allocation of shared resources in flexible manufacturing systems is the main cause of deadlock.Once deadlock occurs, system production will come to a standstill, which will lead to the low productivity of expensive equipment, the economic loss of production enterprises, and sometimes even catastrophic consequences.It is a prerequisite for manufacturing system to obtain high productivity to deal with deadlock problem effectively. Therefore, to find effective methods to prevent and control deadlocks in flexible manufacturing systems has become a hot topic in recent years.Petri net is an important modeling tool, which can describe resource sharing, mutual exclusion, concurrency and conflict.So S3PR net is an important subclass of Petri net model of flexible manufacturing system, which is usually used by most scholars to study the deadlock problem of flexible manufacturing system.The research work in this paper is based on S3PR nets, which mainly focuses on reducing the structural complexity of active Petri net controllers and improving their behavior permissibility, as well as reducing the computational complexity of solving active Petri nets controllers.The main research results of this paper are as follows:1.The existing deadlock control strategy is usually based on the beacon to add the control library, and finally get the active controller.By analyzing the characteristics of the control library which is added to the deadlock control strategy based on beacon, this paper proposes a method for detecting redundancy of the control library based on the ranking of beacon resources.The active Petri net controllers obtained by the existing deadlock control strategies often contain redundant control libraries. The advantage of the proposed method is that it can eliminate the maximum number of redundant control libraries and is independent of the order in which the redundancy of the control libraries is detected.The resulting active controller has a simple structure and more permissive behavior.2.In this paper, a method of designing optimal controller based on necessary control library is presented.In general, the active controller obtained by this method has better performance in terms of behavior permissibility and structural complexity.Especially when the input active controller contains more than one set of necessary control libraries, the advantages of the proposed method in terms of behavior permissibility and structural complexity are more obvious.The solution of optimal controller has been a hot topic in the design of active Petri net controller.Two examples of flexible manufacturing systems in this paper show that the proposed optimal controller can obtain near optimal behavior permission with a simple structure.Finally, on the basis of summarizing the full text, the future research work of the flexible manufacturing system active controller simplification technology based on Petri net is prospected.
【学位授予单位】：浙江工商大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH165

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