PLC在柔性制造系统托盘交换控制中的应用

１引言物料自动输送与贮运系统是柔性制造系统（ＦＭＳ）的重要组成部分，其主要任务是通过物料小车完成在装卸站、托盘库和加工中心三者之间工件的自动存贮运送和交换，它担负着使ＦＭＳ物流畅通、高速运行的重任，本文就ＦＭＳ物料系统托盘自动交换采用ＰＬＣ控制进行讨...     

有限缓冲区FMS的特征分析与托盘配置

本文研究了Ｊｏｂ－Ｓｈｏｐ型有限缓冲区ＦＭＳ的运行特性及托盘优化配置问题，给出了系统的分析模型及托盘优化算法。本文的结果对系统的分析与设计具有重要的实际意义。     

不完全柔性制造系统的最优控制

考虑具有随机需求的不完全柔性制造系统的最优控制，系统在各种产品间的切换时间是不可忽略的。运用马尔可夫最优决策过程归纳方法，导出机器服务率的最优控制策略。通过分析最优值函数的性质，证明最优策略具有简单的阈值结构，从而可得到次优生产策略--阈值控制策略。     

整合Petri网和蚁群优化算法用于柔性制造系统调度优化研究

以Petri网与蚁群优化算法相结合，求解柔性制造系统的调度问题，取得了明显的优化效果。以一个典型算例的调度优化为例，证明了算法的有效性。     

考虑混合型号托盘的托盘共用调度随机规划模型

如何将托盘科学地在系统内调度是目前托盘共用系统管理者们亟待解决的问题。面对各类参数的随机性和多种多样的托盘,管理者很难仅凭经验做出科学的决策。利用随机机会约束规划的方法,构建了考虑混合型号托盘的托盘共用系统调度随机规划模型,使用确定性等价转化的方法将机会约束转化为了其确定等价形式,通过算例进行了数值求解和分析,验证了模型的有效性,提出了决策策略建议。     

输入随机的不可靠柔性制造系统的反馈控制

对于具有随机输入和随机需求的一类不可靠柔性制造系统,利用转移率一致化技术和随机动态规划方法,给出了输入率和服务率分配的最优反馈控制策略,指出系统的最优控制具有bang-bang形式的天关结构,数值例子验证了文中的结果。     

托盘共用系统托盘回收随机规划模型研究

介绍了托盘共用系统的研究现状,并在现有托盘共用系统的基础上,提出一个改进的托盘共用系统.基于改进的托盘共用系统,建立了托盘共用系统托盘回收随机规划模型,模型中考虑了需求和运输能力不确定等因素,采用机会约束规划方法对模型进行了确定性等价转换.通过算例进行了数值求解和数值分析,验证了模型的有效性,得出了一些有意义的结论.     

柔性制造系统的仿真研究

本文介绍柔性制造系统的仿真研究。该系统是由中央管理系统,物流控制系统,加工单元和监视摄象系统四部份组成。用柔性自动化技术加工“伺服电机”的主要零件。并要求现在这条柔性制造系统由年产约1000台电机,提高到年产5000台。根据仿真研究结果,在此系统的3号工位必须增加2台数控车床,并采用一天工作二班制(16小时),才能满足要求。文中介绍了柔性制造系统的结构,仿真模型的魏立,仿真结果的分析。     

同尺寸物品托盘装载的动态规划算法

对同尺寸物品托盘装载问题,提出一种动态规划算法。本文将三维托盘装载问题转化为一系列的二维排样问题来求解。通过对动态规划算法的研究,设计出了适合同尺寸物品的三维托盘装载的算法,并通过实验证明了算法的有效性。     

Time-Optimal Coordination of Flexible Manufacturing Systems Using Deterministic Finite Automata and Mixed Integer Linear Programming

Automation and flexibility are often mentioned as key concepts in modern production industry. To increase the level of flexibility, deterministic finite automata (DFA) can be used to model, specify and verify the production systems. Often, it is also desirable to optimize some production criteria, such as for example the cycle time of a manufacturing cell. In this paper, a method for automatic conversion from DFA to a mixed integer linear programming (MILP) formulation is first presented. This conversion is developed for a number of DFA structures that have shown to be useful in practical applications. Special attention is paid to reducing the search region explored by the MILP solver. Second, a conversion from the MILP solution to a DFA supervisor is described. This allows to combine the advantages of DFA modeling with the efficiency of MILP and supervisory control theory to automatically generate time-optimal, collision-free and non-blocking working schedules for flexible manufacturing systems.

Economic Analysis of a High-volume Flexible Manufacturing System by High-speed Processing

Agility in manufacturing requires a quick response to the changes in quantity of products without losing productivity. A high-volume flexible manufacturing system (HV-FMS) attains the high flexibility as well as the high volume production. We consider in this paper the energy-saving effect of HV-FMS from the viewpoint of consumed electric power. We take a production system of cylinder heads for automobile engines as a subject in this study, and draw a comparison of the energy-saving effect between HV-FMS and flexible transfer line to verify the effectiveness of HV-FMS. Moreover, we discuss the economic effect of high-speed processing at HV-FMS. We measure the energy-saving effect by high-speed processing and give the permissible level for additional tooling cost.     

Intelligent Jig System to Automate Flexible Manufacturing System

Jig pallet systems are intended for the automatic, complete machining or assembly of parts families in the area of medium and large scale manufacturing. Their distinctive feature is that several machine tools, or assembly machines, are linked together to generate an overall system by means of common tool and workpiece supply with integrated computer control. A jig pallet system is considered to be intelligent, if its central processor is equipped with a knowledge-base and an inference-engine. A jig pallet system was structured. It consists of a central processor, tools supply system, workpiece supply system, manufacturing cell which includes four work stations and a local area network. A knowledge-base and inference-engine were developed to reason the next position of jig pallet systems. The jig pallet system, with its incorporated knowledge-base and inference-engine, was tested for a large variety of operational parameters to explore the ability of the central processor to control participant's operations. The conclusion which is derived from these tests is that the central processor can control and optimize participant's operation in real time with minor effects on the system efficiency.     

Object-oriented software modeling of a Flexible Manufacturing System

Flexible Manufacturing Systems play an important role in improving our manufacturing productivity. Simulation is emerging as a popular tool in modeling FMS for analyzing its performance in the area of production planning/scheduling. In this paper, we illustrate how to model a Flexible Manufacturing System in the object-oriented paradigm using an example. We present a systemtic approach to the design of object-oriented programming systems based on a combination of data modeling and event analysis techniques.An entity relationship approach is used as the basis for an initial decomposition of the system into objects. The design is refined by an analysis of the events the objects participate in. The design is implemented in Objective-C. Finally, we describe ways in which this model of an FMS can be extended to explore popular research questions in production planning and scheduling.     

Design of Optimal Petri Net Supervisors for Flexible Manufacturing Systems via Weighted Inhibitor Arcs

This paper develops an approach to the design of an optimal Petri net supervisor that enforces liveness to flexible manufacturing systems. The supervisor contains a set of observer places with weighted inhibitor arcs. An observer place with a weighted inhibitor arc is used to forbid a net from yielding an illegal marking by inhibiting the firing of a transition at a marking while ensuring that all legal markings are preserved. A marking reduction technique is presented to decrease the number of considered markings, which can dramatically lower the computational burden of the proposed approach. An integer linear program is presented to simplify the supervisory structure by minimizing the number of observer places. Finally, several examples are used to shed light on the proposed approach which can lead to an optimal supervisor for the net models that cannot be optimally controlled via pure Petri net supervisors.     

柔性制造单元的一种调度算法

本文提出了一种新的柔性制造单元的调度算法,它在离散周期控制的基础上加上事件中断以适应系统状态的随机干扰,在流控制中,我们不仅决定产品类型的混合比,同时决定每种工件在各加工路径的比。文中给出了一个制造单元的仿真结果,它表明了算法的有效性。     

Maximally Permissive Petri Net Supervisors for Flexible Manufacturing Systems with Uncontrollable and Unobservable Transitions

This paper presents a deadlock prevention policy to obtain behaviorally optimal supervisors for flexible manufacturing systems with uncontrollable and unobservable transitions. The conditions of uncontrollability and unobservability of transitions are revealed in the sense of the implementation of a Petri net supervisor. Then, integer linear programming models are designed to obtain a Petri net supervisor such that all legal markings are reachable and the number of control places is reduced. We also show that a controllable transition can be unobservable and self‐loops can be used to disable the transition but do not observe its firing. Finally, examples are provided to illustrate the proposed approach.     

Study on Robot Sequencing Model in Flexible Manufacturing System Using Timed Petri Net

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