Design and Analysis of a Closed-Loop Single-Workstation PPC System

Methods at control engineering can be integrated with methods of production engineering to improve robustness and performance of production systems, while making dynamic analysis tractable and improving understanding of complex behavior. In this paper a discrete, dynamic model of a single workstation is developed, including characteristic equations of transfer functions that are useful in choosing control parameter values according to desired dynamic performance and response. Nonlineartties such as dependence of capacity on WIP and delay in adjusting capacity due to work rules are modeled and incorporated into the dynamic analysis. Examples are presented of control parameter selection and resulting performance.     

Restart policies to maximize production quality in mixed continuous-discrete multi-stage systems

In sectors as semiconductor fabrication, pharma industry and food production, discrete production processes are intertwined with continuous production processes. Since continuous processes frequently produce large batches of material requiring fairly long processing times, restart policies aiming at scrap reduction especially due to work-in-progress perishability are commonly used to control the material flow in multi-stage production systems. A performance evaluation model integrating control mechanisms is proposed to assess the impact of local restart policies at system level. A real case study in the food production is presented, where the parameters of restart policies are optimized to maximize production quality.     

Backlog Control Design for a Closed Loop PPC System

In this paper a discrete dynamic model of a single workstation is used to design and analyse control algorithms for closed-loop PPC that improve performance, especially response to disturbances such as rush orders and periodic fluctuations in capacity, while ensuring that dynamic behavior remains favorable and robust. The presence of delays in adjusting capacity presents challenges in both dynamic analysis and control algorithm design that are addressed in the paper. Methods of control engineering, such as transfer function and frequency response analysis, are used to make analysis of fundamental system properties tractable and to improve control of dynamic behavior.     

Modelling and Control of Production Systems based on Nonlinear Dynamics Theory

Today's highly dynamic market with its rapid changing demand requires highly dynamic order processing in very flexible production systems. Most conventional production planning and control methods do not support such fast-moving activities. A dynamical approach is introduced for modelling and control of production systems. It was developed from concepts of the Nonlinear Dynamics Theory. Manufacturing processes as well as planning and control mechanisms are seen as one unit toward the establishment of a dynamical system. The dynamical approach includes an analysis of the dynamic behaviour of the production system as well as the control of the manufacturing process by a continuous adjustment because of changes or disturbances in the environment or in the production system itself.     

基于AMESim水下液压控制系统仿真分析

复合电液控制是目前深水油气田开发应用较多的控制方式。对水下液压控制系统进行分析,对主要的液压参数如操作压力,HPU蓄能器、水下蓄能器容积进行计算;依据南海某油气田工程实际,应用AMESim建立水下电液复合控制系统充压仿真模型,仿真模拟不同脐带缆管径对系统充压和ESD的影响,并利用AMESim仿真软件对南海某油田液压控制系统典型工况进行建模和动态仿真。仿真结果表明,该液压系统的各项性能指标均满足相应标准规范和工程的要求。该仿真研究为脐带缆管径选择提供参考,对水下液压控制系统的关键元部件选择分析有很好的参考和指导作用。     

电液负载模拟器力矩控制伺服系统不确定性的分析研究

电液力矩伺服控制系统常用于电液负载模拟器（EHLS）以模拟航空动力铰链力矩,从而实现对目标的动态加载。由于系统存在不确定性和非线性因素,影响了系统的控制性能和稳定性。本文通过对电液负载模拟器系统模型的分析,详细论述了造成系统不确定性的原因。同时针对参数不确定性、模型不确定性及强外干扰产生的不确定性进行了仿真研究。仿真结果明确了各种不确定性对该类系统的影响程度,为采用相应的控制策略以消除多余力矩、提高系统性能提供了理论依据。     

气动板形仪测力系统动态性能分析

气动板形仪是一种有色金属箔材在线实时检测、控制板形的专用张力传感器。针对高速及超高速带材生产的实时特点,研究该传感器的动态性能对其检测控制系统设计具有重要意义。分析气动板形仪测力系统的组成,建立其机械动力学模型,并推导了测力系统的传递函数。分析系统在欠阻尼时单位阶跃和单位脉冲信号的动态响应,得出的结论为气动板形仪测力系统的设计和性能分析提供了理论依据。     

Real-time capable Finite Element Models with closed-loop control: a method for Hardware-in-the-Loop simulation of flexible systems

Modern simulation methods are increasingly applied in all areas of research and development in production engineering. Moreover, the application area can be extended by the combination of different simulation tools e.g. Finite Element Method (FEM) with Computer Aided Control Engineering (CACE). The dynamic behaviour of machine tools depends not only on their distribution of mass, damping and stiffness, but also on their applied control mechanisms. The following article presents a method for simulating the influence of the actual control system on the structural dynamics in real-time by using Hardware-in-the-Loop Simulation.     

基于ADAMS的理想铰约束模型的局限性研究

针对在多体系统动力学分析中采用理想铰约束模型模拟关节轴承的铰接功能引起仿真结果出现偏差的问题,以基于虚拟样机技术的组合臂架式门座起重机变幅过程的动力学分析为例,将其中的两个主要铰接点视为含间隙的滑动轴承,运用含间隙矢量模型、非线性连续接触碰撞力的混合模型和修正的库仑摩擦模型,综合考虑铰链间隙、接触变形和摩擦等因素的影响,求解了系统在典型工况下的动力学响应,并与按照理想铰约束模型得到的响应结果进行对比,揭示了理想铰约束模型存在的局限性,为如何在工程机械动力学分析中合理使用理想铰约束模型提供了参考。     

生料带分卷机速度与张力控制建模与仿真

生料带分卷过程中张力变化过大会导致收卷质量不高。张力控制由于材料存在拉伸变形，要得到系统的精确模型比较困难，适合采用PID控制方法。文章在简化了的速度与张力控制模型的基础上利用MATLAB的SIMULINK工具建立了一个仿真模型。根据实际生产条件设定仿真参数，仿真结果表明该方法能准确地模拟卷绕过程中的速度与张力控制的动态过程。     

A Connectionist Production System with Partial Match and its Use for Approximate Reasoning

The paper discusses a connectionist implementation of knowledge engineering concepts and concepts related to production systems in particular. Production systems are one of the most used artificial intelligence techniques as well as a widely explored model of cognition. The use of neural networks for building connectionist production systems opens the door for developing production systems with partial match and approximate reasoning. An architecture of a neural production system (NPS) and its third realization—NPS3, designed to facilitate approximate reasoning—are presented in the paper. NPS3 facilitates partial match between facts and rules, variable binding, different conflict resolution strategies and chain inference. Facts are represented in a working memory by so-called certainty degrees. Different inference control parameters are attached to every production rule. Some of them are known neuronal parameters, receiving an engineering meaning here. Others, which have their context in knowledge engineering, have been implemented in a connectionist way. The partial match implemented in NPS3 is demonstrated on the same test production system as used by other authors. The ability of NPS3 for approximate reasoning is illustrated by reasoning over a set of simple diagnostic productions and a set of decision support fuzzy rules.     

复杂激励下变速箱箱体动态响应分析

动态响应分析用于确定结构承受随时间变化载荷时的动力响应,是工程技术中最普遍的分析内容。对于变速箱箱体来讲,由于运行时轴承处作用力是随时间不断变化且不规则的,因此很难建立准确的激励函数并进行动态响应分析。利用ADAMS建立变速箱传动系统的动力学仿真模型,通过多体动力学分析,得到箱体各轴承座处的动态力;在此基础上利用有限元ANSYS软件将轴承作用力施加到箱体上,并对箱体结构进行了动态响应求解,通过实验验证了该复杂响应分析的可行性。     

大型技术改造工程项目管理实践

大型技术改造工程项目管理是一个复杂、系统的过程,既要考虑原有资源的综合协调利用,又要兼顾现有生产与工程建设两不误、共促进,技改工程中管理模式的创新、方案优化控制、制度规范激励控制以及有效的协调等管理方法的成功应用和实践,将有效实现技改工程良好的经济效益和社会效益。     

数控折弯机电液比例控制技术的研究

钣金折弯过程中因折弯机双缸电液比例模型参数的差异与时变以及折弯负载力干扰等导致系统指令跟随误差和双缸同步误差增大,为减小这种误差给生产效率和机床工况带来的不良影响,提出了一种基于迭代前馈和单神经元PID的复合控制算法,利用单神经元PID的自适应能力提高系统对折弯负载力干扰的鲁棒性,通过迭代学习前馈控制提高系统的快速跟随性,并引入交叉耦合控制改善双缸同步性。折弯实验结果表明：该复合控制算法较工程中常用的PID算法,不仅使得最大跟踪误差和最大同步误差分别从2.1 mm和0.14 mm减小到0.5 mm和0.055 mm,改善了机床加工工况,而且折弯工进的定位周期缩短了约18%,提高了生产效率     

球墨铸铁中珠光体开始转变动力学数学模型

珠光体球墨铸铁正大量地被应用于许多重要、关键汽车零件的制造之中．但是珠光体球墨铸铁零件的生产过程和其质量及性能却不能得到有效的控制。根据Johson-Mell珠光体转变动力学理论和Hiller珠光体长大理论，采用待定系数法，求得了能够正确描述球墨铸铁中珠光体转变真实过程的动力学数学模型。并对连续冷却条件下珠光体的连续转变作了深度的分析。通过球墨铸铁的连续冷却实验．证明了该数学模型的科学性、合理性和可行性，可应用于珠光体球墨铸铁的实际生产中，指导生产工艺的制定和对产品质量、性能的预测、控制，具有高的学术价值和工程应用价值。     

基于物联网技术的动态GRNN模型的液压系统故障检测研究

液压系统因其独特的特性,在各个领域有着广泛的应用。液压设备的运行安全与状态监测是生产中的一项重要内容。由于液压系统的所有部件都在封闭油路中工作,故障源的定位比较困难。为了解决这个问题,本文提出了一种基于物联网技术的动态故障诊断方法GRNN模型的基于物联网的智能控制,利用无线传感器网络技术在分布式液压设备中各参数的实时测量和控制,远程数据共享、故障信号的采集输入GRNN模型故障观察器,检测阈值,通过实验模拟准确诊断系统故障。实验表明,该方法可以有效地应用于过程生产液压系统中,保证系统的正常运行,降低设备故障率,提高生产效率。     

基于Modelica的潜液泵系统建模与仿真分析

为研究潜液泵系统的动态特性以及速度限制扭矩控制阀(STC阀)结构参数对阀芯动态性能的影响,在分析其工作原理、数学模型的基础上,采用多领域统一建模语言Modelica,在MWorks仿真软件中构建STC阀子系统、遥控阀组子系统等模型,并将所建立的子系统模型与恒压变量泵、离心泵模型相结合,构造出完整的潜液泵系统模型。利用该模型进行系统仿真,分析STC阀节流孔直径和阀芯质量对阀芯动态性能的影响。研究结果表明:潜液泵系统具有良好的动态特性;STC阀节流孔直径越小,阀芯的运动速度越平稳、速度振荡越小,越能更快达到稳定状态;STC阀阀芯质量越大,阀芯的速度振动越小,运动速度越平稳。     

基于板坯连铸结晶器液压振动系统的集成测试研究

结晶器液压振动系统是板坯连铸机的核心装备之一,其动态响应性能直接影响到铸坯的质量,是评判振动系统是否满足生产的依据。通过对板坯结晶器液压振动系统集成测试的研究,获取液压振动的动态响应等参数,并评判振动系统是否满足设计需求,为工程设计和现场调试提供技术支持。     

基于迭代学习的6-DOF平台控制与仿真研究

在建立某型模拟器平台动力学模型的基础上,提出一种迭代学习控制(ILC)算法。通过多体系统动力学分析软件ADAMS建立虚拟样机模型,运用Matlab/Simulink建立控制策略模型,利用接口文件将两者结合起来进行机械系统与控制系统的联合仿真。结果表明:联合仿真具有较好的直观性和分析的快速性,验证了迭代学习控制策略的优越性,对控制器的设计与验证具有重要的借鉴意义。     

泵控多缸液压同步系统的研究及模拟试验

本文对多缸液压同步系统建立数学模型,进行动态分析,并提出了同步系统模拟试验和计算机在线检测的新方法。目前,该成果已成功地用于多条大型自动生产线设计上,实践表明高效实用,经济效益显著。