Identification of metrics and transition functions of pull system implementation

This research examines the problem of providing decision support for the transition from a traditional push production system to a pull system design. The methods presented include: a method for determining significant metrics of evolving production systems; a method for estimating associated transition functions; and a decision support system framework which gives guidelines for development of software employing these methods. An actual electronics assembly system provided a case study. Significant metrics for this system were determined to be quality, material flow congestion and system flexibility. Recursive equations for estimating these transition functions and a decision support system framework are given.     

Experimental identification for inverse problem of a mechanical system with a non-minimum phase based on singular value decomposition

This paper presents experimental results of source identification for a non-minimum phase system. Generally, a causal linear system may be described by matrix form. The inverse problem is considered as a matrix inversion. Direct inverse method cannot be applied for a non-minimum phase system, because the system has ill-conditioning. Therefore, in this study the SVD inverse technique is introduced to execute an effective inversion. In a non-minimum phase system, its system matrix may be singular or near-singular and has very small singular values. These very small singular values have information about a phase of the system and ill-conditioning. Using this property, we could solve the ill-conditioned problem of the system and then verify it for the practical system (cantilever beam). The experimental results show that the SVD inverse technique works well for a non-minimum phase system. This inverse technique can be applied to the estimation of the magnitude of impact force, which becomes often a cause of damage to a mechanical system.     

多自由度无阻尼动力吸振器的理论研究

讨论了将简谐激振下无阻尼单自由度主系统的动力消振原理推广到多频谐波激励下无阻尼多自由度主系统的情况,通过选择一个合适的多自由度无阻尼动力吸振从系统。即从系统的固定频率正好是所有的激振力的频率,可以完全消除多频谐波激励下无阻尼多自由度主系统中某质点的振动响应。还讨论了根据给定弹簧-质量系统的特征值及对该系统进行小的、已知的修正后所得系统的特征值,来直接重构质量矩阵和刚度矩阵的方法。     

A knowledge-based system for the strategic control level of robots in flexible manufacturing cells

The strategic control level synthesis for robots is related to a hierarchical robot control problem. The main control problem at the strategic control level is to select the model and algorithm to be used by the lower control level to execute the given robot task. Usually there are several lower control level models and algorithms that can be used by the robot control system for every robot task. Strategic control level synthesis depends on the particular robot system application. In a typical application, when the robot system is used in a flexible manufacturing system for manipulating various part types, the robot tasks executed by the robot system depend on the manufacturing processes in the system. If the robot system is applied in another flexible manufacturing system, dedicated to other manufacturing processes, another set of robot tasks might be needed to perform the necessary operations. Therefore, the quantity and the kind of knowledge required in the system for the strategic control level differ from one application to another. Such a fact creates the appropriate conditions for employing some artificial intelligence techniques. This article describes a knowledge-based system approach to the strategic control level synthesis problem.     

NON-THERMAL PLASMA AT ATMOSPHERIC PRESSURE: SYSTEM DESIGN AND DEVELOPMENT

The low-current non-thermal atmospheric plasma source is a useful cost-effective tool for many applications. One of the major applications of this source is to reform hydrocarbons to produce hydrogen. Here, the focus is on the design and development of a system for this process. The system described uses much lower current compared to the other thermal plasma systems and operates at atmospheric pressure eliminating the need for an expensive vacuum system. The system consists of a plasmatron, a fuel injection system for both liquid and gaseous forms, a window for inserting diagnostics systems, and a system to collect output signals from plasma. The non-thermal plasma was produced at high pressure with an AC high-frequency power supply. A three electrode system (copper, stainless steel 314, and nickel) were used with four different configurations. Initial discharge characteristics have been measured for all electrode configurations. The breakdown properties of the system with the electrode configurations and corresponding ionization coefficient (α) have been estimated. A cylindrical Langmuir probe was used to measure and estimate relevant plasma parameters.     

A re-configurable cross-sectional imaging system for reverse engineering based on a CNC milling machine

This paper presents a novel reverse engineering digitizing system for full part geometry, which is based on a cross-sectional imaging device built in a NC milling machine. The system successively captures a picture for each planar cross-section contour of the part by end-milling and CCD imaging, and builds the geometry for both external and internal surfaces of the complex 3D part based on a set of the vectored cross-sectional contours. The system mainly consists of three components: a NC milling machine, a cross-sectional imaging device and a computer control unit. Some issues involving the principle and process flow of the system, encasing materials, cross-sectional imaging and NC code generation, etc. are described in detail. Built on an existing NC milling machine, a portable device for capturing the cross-sectional images is designed, which includes an isolated light source, a digital camera, a protective case, a rigid arm and a robust tripod. The device, connected to a computer control unit, serves as a highly flexible accessory for the NC milling machine, constructing the cross-sectional imaging system for reverse engineering. Furthermore, the error analysis and accuracy assessment of the system are also addressed. A typical case is discussed in detail to illustrate the applications of the system. Such a re-configurable digitizing system for reverse engineering offers a number of advantages, such as the functional extension of an existing NC milling machine, low costs, and rapid construction. As a result, this system provides a feasible and useful scheme for many enterprises to construct their own reverse measuring system based on existing equipment to aid in rapid product development and extend the function of existing equipment.     

基于状态重构的控制系统校正与仿真

基于状态重构的思想,针对控制系统中的一些不稳定因素和经典PID校正的局限性,应用现代控制理论,从系统性能要求出发,探讨了一种状态反馈校正的方法,对其中的一种典型模型进行了校正,使原系统不仅达到稳定,而且与应用经典控制理论的PID校正相比更具有良好的动态特性.最后用Matlab对校正的系统进行了对比仿真分析,从而证实了校正方法是有效的.     

基于绿色设计准则的柴油机微粒袋滤器系统的研制

介绍了绿色设计在环境、材料、结构等方面的准则 ,并运用于柴油机微粒袋滤器系统的研制中 ;为实现系统的“绿色度”,本文提出达标控制 ,并进行了软、硬件开发 ;最后 ,将系统在 4 85 Q柴油机台架上进行了初步实验 ,证明该系统有较好的响应性 ,可实现对系统的控制功能     

渐开线型面专用数控加工系统的开发

介绍了涡旋式空气压缩机涡盘渐开线型面加工专用数控系统,并研究了专用数控系统的硬件结构,以及运用系统工程的思想对其软件进行开发的方法。该数控系统经实际生产运行证明其加工精度和工作可靠性均较高,为我们在专用数控系统软件的开发方面提供了一定的经验。     

用于地铁隧道形变监测的图像处理系统

地铁隧道形变监测系统对于长时间运营、结构体受到多种应力影响的隧道安全性保障有重要意义。以解决现存隧道健康监测系统过于高昂的成本为目的,提出了一种图像处理系统用于完成监测系统的测量工作。测量设备基于嵌入式系统,以数字图像处理技术为核心,具有适应性强、成本低、易于维护等特点。     

Construction of an automation system for the inspection and packing processes of a screw/bolt production line

In this paper, a packing automation system was constructed and a prototype was manufactured to test its performance for the inspection and packing process automation of a screw/bolt production line. The packing automation system is composed of an automated inspection system and an automated packing system. An inspection system using machine vision inspection and the slant method was proposed, developed and applied. The system was also developed and applied as the MICOM system in the PLC system to improve inspection errors due to the delays in the inspection process. The feeder to supply work to the inspection device was proposed, developed and applied as a slide feeder by applying a vertical transfer mechanism. The slide method was designed to minimize friction and thus improve upon the disadvantages of the existing bowl feeder. An automated packing system based on a one-station method for two-sided vinyl automatic packing was proposed, developed and applied. The one-station method maximizes the speed of the packing processes, such as automatic supply, cutting, spreading, charging, closing and sealing, that occur over a short distance. Performance of the system was evaluated by producing a prototype and setting up a packing automation system. The performance test was validated based on the inspection handling speed, transfer speed of the slide feeder, packing speed of the automatic packing system and charging accuracy, verifying the applicability and practicality of the automated system for the screw/bolt production line.     

基于Lowtran软件包和Gabor匹配提高紫外告警系统探测距离

紫外告警的虚警率较低但探测距离太近,而红外告警则与之互补。基于此提出一种将紫外告警与红外跟踪相复合的应用于地面设备的新型告警/跟踪一体化模式。重点分析了紫外告警系统的探测机理、捕获条件及作用距离影响因素。据此提出了一种基于Lowtran软件包的紫外告警系统探测距离估算模型,用于精确估算紫外告警系统对近程固体推进剂导弹的探测距离。针对UVCCD图像信号处理对探测距离的重要影响,提出基于Gabor特征的图像匹配方案。通过系统仿真实验,证明该模型在系统硬件不变的条件下能将探测距离估算的准确性控制在5%以内,将目前紫外告警系统的探测距离由最远5km提高到最远8km,大大提高了告警系统的探测质量。本方案模型可用于其他光电探测设备。     

车辆制动系统需液量仿真分析

需液量是制动系统关键性设计参数,目前关于制动系统需液量的研究缺乏理论和仿真依据。通过解析车辆制动系统的结构和工作原理,推导需液量关于制动液压强的数学公式,并基于AMESim的设计探索工具,搭建可自寻优的需液量仿真模型。根据实测数据寻找制动系统仿真模型的最优参数拟合值,并利用自寻优出的模型对制动系统需液量的影响因素进行仿真分析。结果表明,该模型可根据目标需液量反向推导出制动系统的关键设计参数,并用以模拟制动系统的需液量分析,为制动系统的设计和故障诊断提供参考依据。     

综合定量反馈理论与特征结构配置的飞行控制系统优化设计

定量反馈理论(QFT)是一种新颖的频率域鲁棒控制技术,在N ichols图上开展分析与设计。针对大包线范围内系统模型变化大的特点,可采用QFT设计横航向控制器。由于QFT主要针对单输入单输出(SISO)系统进行分析,因此首先应采用特征结构配置(EA)理论将无人机的横航向模态进行近似解耦,将多输入多输出(M IMO)系统转化为SISO系统,再采用QFT进行控制系统设计。本文将两种控制方法结合起来,构成综合优化飞行控制方法,针对某型无人机包线范围内选取的18个状态点组成的控制对象模板进行控制设计,并进行非线性仿真。仿真结果表明设计的控制器使得无人机在全包线范围内具有较好的性能和鲁棒稳定性。     

论重点实验室的对外开放运行及体系建设

实行开放运行是重点实验室的基本要求。本文从充分利用重点实验室的资源,培养创新人才出发,结合本实验室管理实际工作,建立了适合本实验室的一套开放运行体系。在实践中建立、健全了实验室开放管理制度,实现管理制度信息化,并针对不同的实验开放对象建立不同的运行方式。作为重点实验室更要重视智能化网络化管理,实施了门禁控制、视频监控和仪器设备共享管理系统系统,为实验室开放的顺利进行提供了重要保障。     

基于AR模型的磁流变减振系统动态性能研究

研制了磁流变减振器及测试系统,建立了系统的动力学自回归AR模型。通过连续系统传递函数与离散系统的时间序列AR模型的对应关系推导出了三阶系统动态响应性能参数计算公式,分析了系统的减振性能和系统的动态响应,得到了系统的最优工况。     

Higher-order aberration corrector for an image-forming system in a transmission electron microscope

We developed a new electron optical system with three dodecapoles to compensate for spherical aberration and six-fold astigmatism, which generally remains in a two-hexapole type corrector. In this study, we applied the corrector for image-forming system in transmission electron microscope. Compensation for higher-order aberration was demonstrated through a diffractogram tableau using a triple three-fold astigmatism field system, which was then compared with a double hexapole field system. Using this electron optical system, six-fold astigmatism was measured to be less than 0.1 mm at an acceleration voltage of 60 kV, showing that the system successfully compensated for six-fold astigmatism.     

基于拓扑传递的耦合机械故障特征提取方法

旋转机械系统的复杂性,使得其特征参量具有较强的非线性和耦合性,对其进行有效特征提取存在困难。为了提取旋转机械系统耦合故障的特征信息,建立其状态特征信息拓扑空间,并构建旋转机械系统拓扑动力系统模型,基于系统的拓扑传递特性,提出了新的旋转机械系统特征提取的信息空间变换方法。通过跟踪系统特征信息的变换及传递过程,实现对系统特征信息的提取,从一个新的角度为分析旋转机械系统工作特性奠定基础。最后将该方法应用到含油膜力的裂纹故障、碰摩故障及裂纹碰摩耦合故障的旋转机械系统信息特征提取中,并通过仿真实验验证了理论方法的可行性。     

Development of a prototype customer-oriented virtual factory system

Current Computer integrated manufacturing/Enterprise Resource Planning (CIM/ERP) systems require harmony and communication between humans and facilities. A user’s preferences should also be considered in CIM/ERP systems. Virtual factory (VF), also known as virtual manufacturing (VM), systems can fulfill the requirements of current CIM/ERP systems. A VF system simulates virtual production in a virtual factory environment on the computer system which allows optimization prior to going into production. In this paper, we defined a VF system as a pre-analyzing system for designing, engineering and manufacturing a product in the enterprise system of the real world. The objective of this paper is to design a VF system and to develop a prototype system that the customer can participate in and be satisfied with. We selected a telephone as a sample product for the VF system. The VF system consists of four subsystems: virtual product ordering, design, manufacturing, and CIM/ERP interface. The prototype system aims to develop a virtual product ordering and design system.     

A value-based maintenance optimization method for failure prevention based on reliability modeling of a hybrid assembly system

The effective maintenance policy for the fixtures of the assembly system will guarantee good process capability and product quality to a great extent. Traditional maintenance schedules for the assembly system, such as a constant reliability index as the maintenance trigger, are always based on the fixed maintenance threshold in engineering practice. It always results in down time of the process, unqualified products or the excessive maintenance costs. The aim of this paper is to present a method to optimize the maintenance schedules for a serial-parallel hybrid assembly system. Based on the production chain definition of the hybrid system, a reliability evaluation method by integrating the process performance of the hybrid assembly system and product qualities is proposed. On the basis of the reliability method, a value-based preventive maintenance optimization policy for the fixture components is presented to prevent system failures. Compared with the traditional reliability threshold method for maintenance, the proposed maintenance method generates more value on the premise that the system status and product quality are guaranteed. A case study is used to illustrate the proposed method and validate the effectiveness and advantages.