基于赋时有色Petri网离散制造过程控制系统建模与仿真研究

发布时间：2018-01-12 13:05

本文关键词：基于赋时有色Petri网离散制造过程控制系统建模与仿真研究　出处：《长春工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着自动化生产能力不断的提高,以柔性制造为主要生产方式的企业日渐增多。柔性制造系统(FMS)是离散事件动态系统(DEDS)的一个典型分类,其是由统一的信息控制管理系统、物料运输及贮存系统和一系列数字控制加工设备组成,能适应加工对象变换的自动化机械制造系统。而柔性制造系统的运行,除了对预订的加工工艺进行工作外,在系统中还会出现各种突发性的情况。在资源有限的情况下,如何对资源进行有效的配置,是提高整个系统生产效率的关键所在。为提升效率,对整个生产系统直接进行改造是极其不现实的,所以要利用计算机仿真技术对整个系统进行建模,根据生产实际改变模型相应变量,从而得到相应的结论。系统调度与控制的研究方法常见的有：启发式算法派遣规则,马尔科夫链法,排队网络方法,数学方法,人工智能等。但这些方法多以稳态、独立性为假设前提,系统中不一定完全能够满足这些要求,所以不能保证得出结论的正确性。Petri网具有直观、易懂和易用的优点。不仅可以有直观的图形表示也有严谨的数学表达公式。既可以用于静态结构分析也可用于动态行为分析,所以,以Petri网建模和Flexsim仿真相结合的方案对柔性制造系统进行分析。首先运用Petri网对整个的系统所涉及的对象进行建模,该模型是对整个系统的静态逻辑结构进行建模,着重表达各个对象之间的逻辑关系,基本Petri网可以对一些简单的逻辑关系进行很好的表达,但当Petri网所描述的对象数量增加时,Petri网中的节点数量会呈指数爆炸增长。为了减少整个网系统的节点数量,本文引入了带有颜色因素的Petri网,即有色Petri网。通过对网中的流动资源——托肯,赋予颜色,也就是相同或不同的特征值,以此来给Petri网进行分层,来减小整个网系统的规模。基本Petri网所有的动作都是瞬时完成的,实际系统的加工时间,物流消耗时间等在Petri网中的表达则需要引入时间因素。Petri网只对系统进行了静态逻辑结构建模。Flexsim仿真软件则可对生产系统进行动态仿真。Flexsim是一款3D可视化的仿真软件,其不仅有面向对象的建模技术,还可以对建模系统的数据进行分析。通过Petri网与Flexsim之间的转换,根据Petri网设置相关参数,运行并得出数据。通过建立生产系统的仿真模型,分析了模型中存在的冲突、死锁等情况,本文提出了容量预警机制来反馈调节系统的发料速度。对于生产平衡率的问题,提出了运用启发式算法的SPT规则,合理的解决了生产过程中资源流动与利用的问题,有效地改进了生产设备的平衡率。对生产系统的控制调度、优化改造是一种很好的探索,具有重大意义。
[Abstract]:With the increasing of automatic production capacity, more and more enterprises take flexible manufacturing as the main mode of production. Flexible manufacturing system (FMS) is a typical classification of discrete event dynamic system (DDS). It is composed of a unified information control management system, material transportation and storage system and a series of digital control processing equipment, which can adapt to the automatic mechanical manufacturing system. In addition to the work of the processing process, there will be a variety of unexpected situations in the system. In the case of limited resources, how to effectively configure the resources. It is the key to improve the production efficiency of the whole system. In order to improve the efficiency, it is extremely unrealistic to directly transform the whole production system, so we should use the computer simulation technology to model the whole system. According to the production practice, the model variables are changed, and the corresponding conclusions are obtained. The common research methods of system scheduling and control are: heuristic algorithm dispatch rules, Markov chain method, queuing network method. Mathematical methods, artificial intelligence, etc., but most of these methods are based on the assumption of steady-state and independence, the system may not be able to fully meet these requirements. Therefore, the correctness of the conclusions can not be guaranteed. Petri nets are intuitionistic. Easy to understand and easy to use. Not only can have intuitive graphical representation but also have rigorous mathematical expression formula. Can be used in both static structure analysis and dynamic behavior analysis, so. The FMS is analyzed by combining Petri net modeling and Flexsim simulation. Firstly, the whole system object is modeled by Petri net. This model is to model the static logic structure of the whole system, focusing on expressing the logical relationship between the objects. The basic Petri net can express some simple logic relations well. However, when the number of objects described by Petri nets increases, the number of nodes in Petri nets will increase exponentially in order to reduce the number of nodes in the whole network system. In this paper, we introduce Petri nets with color factors, that is, colored Petri nets. By giving color to the flowing resource -Tocken in the network, that is, the same or different eigenvalues, is introduced. In order to reduce the scale of the whole network system, all the actions of the basic Petri net are instantaneous completed, and the processing time of the actual system is achieved. The expression of logistics consumption time in Petri net needs to introduce the time factor. Petri net only carries on the static logic structure modeling to the system. Flexsim simulation software can carry on to the production system. Dynamic simulation. Flexsim is a 3D visual simulation software. It not only has the object-oriented modeling technology, but also can analyze the data of the modeling system. Through the conversion between Petri net and Flexsim, the relevant parameters are set according to the Petri net. By establishing the simulation model of the production system, the conflicts and deadlocks in the model are analyzed. In this paper, a capacity early warning mechanism is proposed to feedback and adjust the speed of the system. For the problem of production balance rate, the SPT rule using heuristic algorithm is proposed. The problem of resource flow and utilization in production process is solved reasonably, and the balance rate of production equipment is improved effectively. It is a good exploration and great significance for the control and scheduling of production system to optimize the transformation.
【学位授予单位】：长春工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TP301.1;TP391.9

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