现代仿真技术在制造系统中的应用

制造系统的日趋复杂,给系统的分析设计人员、维护人员和管理者带来很大的困难.在现代仿真理论技术研究中,尤其是在离散事件仿真领域,人们得到了许多处理复杂系统和系统复杂性问题的方法.该文讨论如何将处理复杂系统的仿真方法用于现代制造系统,介绍了对制造系统中随机量的建模方法,并讨论了面向制造系统仿真的软件包,对当前应用比较广泛的通用仿真软件包Extend进行了介绍,最后给出一个使用Extend对制造系统进行仿真的例子.     

离散制造系统规划与仿真建模研究

对离散制造过程的规划、建模和仿真技术进行了研究，建立了面向对象的系统模型，分析了仿真运行机理，通过仿真分析优化生产制造系统性能指标。应用实例，介绍了基于eM—Plant环境进行生产线建模仿真、设备布局、瓶颈分析的过程，为离散制造过程研究提供了有效的方法。     

数字化生产线离散制造过程仿真研究

数字化工厂是目前先进制造技术研究的热点。进行内嵌在生产线数字化制造环境中的离散制造过程仿真研究,建立了面向对象的系统模型,分析了仿真运行机理;同时基于eM-Plant软件开发离散制造过程仿真系统,通过具体的生产线实例说明系统的开发与运行机理,提供数字化生产线离散制造过程仿真研究的有效手段。     

基于eM-Plant的焊接单元物流仿真与分析

制造单元规划设计的优劣对生产系统运行效率有显著影响,针对制造单元规划问题,本文利用eM-Plant对某企业焊接单元物流过程进行建模和仿真分析。通过模型运行仿真,得到物流评价参数、设备使用情况和工人工作情况,分析了设备的利用效率,并对存在的问题提出整改方案。     

保守时间窗同步策略的研究与实现

为推进并行离散事件仿真技术在复杂制造仿真系统中的应用,提高仿真效率,针对制造系统仿真模型,研究和实现了一种基于时间窗的受限滞后保守同步策略。阐明了策略的思想,具体分析了策略中距离矩阵、关联矩阵、时钟推进等关键要素,给出了策略的实现流程。实践表明了该同步策略具有建模容易,仿真效率高的特点,为仿真模拟复杂制造系统提供了较好的同步机制。     

基于设备状态管理的制造系统可靠性仿真

该文利用仿真方法研究制造系统的可靠性。首先,讨论了仿真方法的优点;接着,给出了仿真系统的总体框架,利用面向对象的方法建立了制造系统的通用仿真模型,分析了以往仿真系统的局限性提出了基于设备状态管理的仿真方法。为减少由于生产计划变动过于频繁而造成的损失,该文提出了一种以生产计划稳定性为目标的故障问题处理方法。最后,给出了仿真的总流程及实现算法并通过一个实例演示了系统的功能。实践证明该仿真系统可以比较真实地模拟实际生产过程。     

企业仿真分析系统的设计研究

该文针对离散制造企业,将计算机仿真优化技术引入到企业分析领域,归纳了企业综合评价体系。建立了企业仿真优化系统的框架,对该系统中的企业建模方法、仿真环境设置、评价体系建立和仿真引擎等关键技术进行了讨论。     

面向生产制造过程的虚拟仿真系统建模研究

传统的仿真建模技术不能满足对复杂生产制造过程进行仿真的要求。通过对生产制造系统结构特点及其运行方式的研究并结合面向对象的设计方法和虚拟仿真技术，给出了面向生产制造过程的三维可视化图形仿零点建模机制及实现方法，该机制将应用在作者自主开发的面向制造过程仿真系统InteVss中。     

基于eM—Plant的焊接单元物流仿真与分析

制造单元规划设计的优劣对生产系统运行效率有显著影响，针对制造单元规划问题，本文利用eM—Plant对某企业焊接单元物流过程进行建模和仿真分析。通过模型运行仿真，得到物流评价参数、设备使用情况和工人工作情况。分析了设备的利用效率。并对存在的问题提出整改方案。     

面向离散制造业数据挖掘技术研究与应用

在对离散制造企业生产过程中的物流数据特点进行充分分析的基础上,利用数据挖掘技术建立面向零部件物流成本的供应商选择优化模型;研究了针对应用问题的关联规则处理策略以完成对所发现知识的理解和利用。提出了改进的Apriori算法并研制一个数据挖掘系统平台来对此构想进行具体的实现。     

Implementing a hybrid simulation model for a Kanban-based material handling system

Plant floor material handling is a loose loop in most assembly plants. Simulation offers a quick, controllable and tunable approach for prototyping complex material handling processes in manufacturing environments. This paper proposes a hybrid simulation approach, using both discrete event and agent-based technologies, to model complex material handling processes in an assembly line. A prototype system is implemented using a commercial multi-paradigm modeling tool. In this prototype, JIT principles are applied to both the production and the material handling processes. The system performance is evaluated and system optimization directions are suggested. The proposed hybrid modeling approach facilitates the implementation of a responsive and adaptive environment in that various “what-if” scenarios can be simulated under different simulation configurations and real-time situations.     

汽车装配线的可视化仿真研究

由于装配系统仿真对象复杂以及传统仿真方法难以建立装配系统的仿真模型,因此该文提出运用面向对象的理论建立汽车装配线的可视化虚拟仿真系统.文中详细论述了实现该仿真系统的关键技术和流程,接着根据离散事件系统的特点介绍了装配仿真系统的仿真策略,最后以某汽车总装车间为例建立了装配线的可视化虚拟仿真系统.通过可视化仿真实现了车间的布局设计和生产过程的动态仿真,并依据仿真结果确定生产线的技术参数以决策生产.     

基于数字孪生的智能车间系统仿真加速测试方法

为解决当前制造系统软件可靠性仿真测试时间长、测试环境难以搭建等问题,提出采用数字孪生技术与智能车间系统仿真加速测试相结合的方法;建立智能车间高保真数字孪生模型替代现实生产车间系统用于制造系统软件的可靠性仿真测试,首先要构建包含产品、设备资源、工艺流程等系统级仿真模型;同时,为仿真车间生产事件流程,在模型中,还需结合生产实际情况,设置设备间通信协议、通信数据以及生产线事件及队列顺序,真实模拟系统运行环境;通过构建步进电机产线数字孪生模型,仿真加工装配流程,运行智能车间系统软件,采用仿真时钟推进机制开展加速测试,验证了该方法的有效性和实用性,对开展工业系统软件高保真快速测试评估具有一定的借鉴意义。     

Combined simulation for process control: extension of a general purpose simulation tool

Combined discrete event and continuous views of production processes are important in designing computer control systems for both process industries and manufacturing. The paper presents an extension of the popular Matlab–Simulink simulation tool to facilitate the simulation of the discrete sequential control logic applied to continuous processes. The control system is modelled as a combined system where the discrete and the continuous parts of the system are separated and an interface is introduced between them. The sequential control logic is represented by a Sequential Function Chart (SFC). A SFC blockset is defined to enable graphical composition of the SFC and its integration into the Simulink environment. A simulation mechanism is implemented which is called periodically from the standard Simulink simulation engine and carries out the correct state transition sequence of the discrete model and executes corresponding SFC actions. Two simulation case studies are given to illustrate the possible application of the developed simulation environment: the simulation of a batch process cell, as an example from the area of process control and an example of a manufacturing system, i.e. the control of a laboratory scale modular production system.     

GEMS: A generalized manufacturing simulator

The purpose of this paper is to describe a Generalized Manufacturing Simulator (GEMS) which can be used in the analysis of complex discrete part manufacturing systems. GEMS is a FORTRAN based analysis program which has been developed to study assembly line or job shop manufacturing environments. However, the current capabilities of GEMS enable a user to model a wide range of industrial, social, and operational problems. Conceptualization of manufacturing environments to the GEMS program is executed via a box/node arc network representation of the manufacturing system. GEMS is an activity-on box (node) simulation program composed of standardized simulation input via specialized boxes and arcs. A box (node)/arc structure can be developed to represent complex material flow patterns, probabilistics branching, routing based on attribute values, resource constraints, cost considerations, and complex queueing characteristics. GEMS can be used to study product flow rates, manufacturing capabilities, and queueing phenomena; assess in-process inventories and raw material storage requirements; determine the effects of alternate sequencing and scheduling rules; different routing and material handling schemes; and the impact of limited resources and increased/decreased production rates. An analysis package has been constructed which normally requires only a representation of the simulated system in terms of a network diagram, and transmission of this diagram to the GEMS program structure through FORTRAN NAMELIST data inputs.     

钢铁企业生产调度与仿真研究

流程工业企业在生产过程中存在如生产量大、过程复杂等特点,因此生产调度在其中处于非常重要的地位。本文针对钢铁流程企业中存在的物料流调度参数多、流程多样、约束种类多等问题,首先进行了问题的数学建模,定义了调度过程中常用的各种参数、基本数学模型、优化指标和相关约束,然后利用改进的遗传算法对问题进行了求解,并通过实际的生产实例的仿真实验,证明了方法的有效性。     

Data driven production modeling and simulation of complex automobile general assembly plant

Flexible manufacturing and customization has long been a topic in modern manufacturing society. However, challenges still remain on the responsiveness of production system to the fluctuation of market demand. In this paper, we developed a data driven simulation methodology to automatically model a production system and rapidly modify the model corresponding to dynamic requirements and real time information. This methodology provides a “rapid prototyping” capability for production system modeling and enables a quick analyzing and remodeling capability to respond to the fluctuation of demands. The approach is developed and applied to an automotive general assembly plant with an online material handling system. A complete information model based on IDEF1X is constructed for this domain specific modeling and simulation. The main simulation modules for assembly line and material handling system of the plant floor are analyzed and a simulator is implemented in ARENA by SIMAN/VBA program. The case study of an automotive assembly plant shows that the data driven approach enables the modeling and simulation of the complex assembly plant in a “real-time” fashion and therefore effectively improve the responsiveness and flexibility of the production line.     

Development of a simulation framework and applications to new production processes in shipyards

Recently, a floating crane is frequently used for the block lifting, transportation, turn-over, and assembly processes in waves. For these production processes, it is important to detect collision in advance between assembly blocks or the block and the other facilities like the wire rope and the barge which are carrying the block. The tension of the wire rope also needs to be calculated to check that the maximum value is less than the safety criteria. In this paper, a mathematical model is constructed based on multibody system dynamics considering the external forces such as the hydrostatic, hydrodynamic, wind force, etc. To observe the dynamic motions of the floating crane and the block, and to calculate the tension of the wire rope, the time and event simulations are performed by solving the mathematical model in the computer. For applying the simulations to the various production processes in shipyards, a simulation framework is developed. The simulation framework consists of a simulation kernel, application-specific modules, a simulation coordinator, development tools, and post-processing tools. The simulation kernel manages both DEVS (discrete event system specification) and DTSS (discrete time system specification) to deal with various simulation requests. The application-specific modules provide the functions used in application systems, such as dynamic analysis, collision detection, visualization, wire rope force calculation, hydrostatic force calculation and hydrodynamic force calculation. The simulation coordinator manages the data of the simulation kernel and the application-specific modules. The development tools provide a development process, a scenario manager, and a simulation model generator. The post-processing tools are used to report the simulation results. The examples of block lifting, transportation, turn-over, and assembly simulations are developed based on the framework to show that the framework is useful for the simulations of the production processes using one or more floating cranes.     

基于虚拟现实的煤矿设备装配仿真系统研究

针对煤矿大型设备装配存在拆装繁琐和成本高的问题,以采煤机、液压支架、掘进机和提升机为研究对象,采用虚拟现实技术设计并实现了一套由虚拟装配子系统、场景仿真与漫游子系统组成的虚拟装配与仿真系统.利用Maya对大型设备建模,通过VS程序设计,在Unity中进行交互控制,实现了设备的虚拟装配与拆卸、采煤工作面的虚拟仿真漫游功能.系统有效地提高了训练效果,形象逼真地再现了煤矿井下生产过程,具有良好的沉浸性和交互性.测试表明:经该仿真系统训练与使用,有效提高了设备实际装配与拆卸能力,同时降低了成本,具有显著的实际应用效果.     

Assembly simulation of multi-branch cables

Cable assembly simulation is a key issue in the computer-aided design (CAD) of products with complex electrical components. In this study, an assembly simulation method is developed to simulate the assembly process of multi-branch cables. First, based on the Cosserat theory of elastic rods, a novel scheme is introduced to model the joints of multi-branch cables. The potential energy of joints is calculated by taking the topology and anatomical features into consideration. Various physical properties are considered. Various constraints, including connectors, collars, and handles are analyzed, based on which the initial conditions of assembly simulation are determined. The configuration of the cable is then calculated by minimizing its potential energy. To increase computational efficiency, GPU acceleration is introduced, which makes the simulation run at interactive rates even for a cable with resolution up to 1000 discrete points. Finally, the proposed algorithm is integrated into the commercial assembly simulation system, DELMIA. Several simulations were performed with our system. It was demonstrated that the proposed method is able to handle cables with complex topologies. In addition, the proposed method is about four times as efficient as a previous method, and it is able to generate realistic configurations of multi-branch cables at interactive rates. Thus, the proposed method is helpful in the assembly process planning of cables.