基于OOPN的柔性制造系统控制过程建模与仿真

发布时间：2018-06-25 13:55

本文选题：柔性制造系统 + 离散事件动态系统　；参考：《长春工业大学》2017年硕士论文

【摘要】：柔性制造作为一种多批量小品种的生产方式能够适应当今制造业发展的要求,并能迅速地向市场提供多种多样的产品。但柔性制造系统在实施过程中存在投资大、风险性及不可预见性高等问题,特别是其控制过程具有异步、并发的离散动态特性,分析、控制难度大,因此对柔性制造系统中的控制系统进行建模与仿真一直是学术界重视和研究的问题。分析柔性制造系统的首要任务就是对其进行建模。本文采用的Petri网是一种结构化的、可视化的描述语言,能够对系统中的事件进行模拟,突出各系统要素间的逻辑关系,捕捉事件发生的先后顺序。因此本文采用Petri网作为建模工具,而基本Petri网描述系统的能力不足,而且随着系统复杂程度的增强,建立模型将会出现组合爆炸等问题。针对以上问题,本文提出一种面向对象的赋时着色Petri网,用以解决诸如节点爆炸、分析难度大、可重复利用性差等问题。本文采用赋时Petri网对其中的变迁赋予时间属性来描述系统中有关时间属性的事件,如加工、运输等;用着色Petri网对其中的状态或变迁赋予颜色属性,用来区分同一类型系统要素的不同个体,以达到减小网络规模的目的;从面向对象的角度,按照属性、行为或状态将控制系统分为若干模块并将其内部运行机制进行封装,系统运行时各对象仅通过对外信息传递的接口进行沟通,使模型更加层次化、简洁化。对象之间的信息传递由门变迁控制,而系统通过控制门变迁的激发来协调不同对象所进行的活动及顺序来解决系统中出现的冲突、死锁等问题。Petri网对系统进行了静态结构和逻辑描述,为了对其进行动态分析,本文将Petri网中的逻辑控制关系和消息传递机制等映射到仿真软件Flexsim中,利用Flexsim面向对象建模的技术驱动Petri网,通过仿真来验证Petri网的动态特性。对模型中各对象的运行状态及结果进行分析,发现系统中存在的突发事件如机床故障、订单加急等状况。针对出现的问题,本文采用一种嵌入式的启发式算法对系统运行中出现的不确定性问题如机床故障、加急订单等通过重新规划加工路径、分配替代加工设备等控制方法,以减少生产系统中诸如设备使用冲突和资源浪费等问题的发生,从而提高柔性制造系统的生产效率。通过对控制系统改进前后的仿真结果进行对比,证明了本文提出的面向对象的赋时着色Petri网在对柔性制造控制系统进行静态描述和动态分析、控制中的有效性和实用性。
[Abstract]:As a multi-batch and small-variety mode of production, flexible manufacturing can meet the requirements of the development of the manufacturing industry today, and can quickly provide a variety of products to the market. However, the flexible manufacturing system has many problems, such as large investment, high risk and unpredictable, especially its control process has asynchronous, concurrent discrete dynamic characteristics, analysis, control is very difficult. Therefore, modeling and simulation of the control system in FMS has always been an important issue in academic circles. The first task of analyzing flexible manufacturing system is to model it. The Petri net used in this paper is a structured and visual description language, which can simulate the events in the system, highlight the logical relationship between the elements of the system, and capture the sequence of events. Therefore, Petri nets are used as modeling tools in this paper, but the basic Petri nets are insufficient to describe the system, and with the increase of the complexity of the system, there will be some problems such as combinatorial explosion. In order to solve the above problems, an object-oriented timed colored Petri net is proposed to solve the problems such as node explosion, difficult analysis and poor repeatability. In this paper, timed Petri nets are used to assign temporal attributes to transitions in the system, such as processing, transportation and so on, and colored Petri nets are used to assign color attributes to states or transitions. In order to reduce the scale of network, the control system is divided into several modules according to properties, behavior or state, and its internal running mechanism is encapsulated from the point of view of object oriented, which is used to distinguish the different individuals of the same type of system elements to achieve the purpose of reducing the scale of the network. When the system runs, each object communicates only through the interface of external information transmission, which makes the model more hierarchical and succinct. The transmission of information between objects is controlled by gate transitions, and the system coordinates the activities and sequences of different objects by controlling the excitation of gate transitions to resolve the conflicts that occur in the system. In order to analyze the static structure and logic of the system, the logic control relation and message passing mechanism in Petri net are mapped to Flexsim. The technology of Flexsim object-oriented modeling is used to drive Petri nets, and the dynamic characteristics of Petri nets are verified by simulation. By analyzing the running state and results of each object in the model, it is found that there are some unexpected events in the system, such as machine tool failure, order rush and so on. Aiming at the problems, this paper uses an embedded heuristic algorithm to control the uncertain problems such as machine tool failures, urgent orders and so on. In order to reduce the occurrence of problems such as equipment conflict and resource waste in production system, the production efficiency of flexible manufacturing system can be improved. By comparing the simulation results before and after the improvement of the control system, the validity and practicability of the proposed object-oriented timed colored Petri net for static description and dynamic analysis of the FMC are proved.
【学位授予单位】：长春工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH165;TP301.1

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