用顺序功能图实现机械手臂及货物传输带的控制

用机械手向传输带上输送货物是生产环节中一个比较重要及复杂的控制问题,常采用PLC进行控制。阐述了用顺序功能图进行机械手臂及货物传输带的控制,具有简单、直观、高效和不易出错等特点,是解决此类控制问题的一种好方法。     

交通信号灯的顺序功能图实现

本文从不同的角度实现了交通信号灯的顺序功能图,通过对比说明了三种方法的优缺点,并在常规顺序功能图设计方法的基础上,提出了针对定时器使用比较复杂的系统的使用比较指令进行顺序功能图设计的实现方法,达到了对顺序功能图的灵活应用.     

基于顺序功能图的工控机VC编程研究

为了在工控机上实现类似于PLC顺序控制的功能,提出了基于顺序功能图的VC编程方法。以一个典型顺序功能图为例,通过单独开线程模拟PLC主扫描循环,从而可以不影响控制系统的其他界面操作;主扫描循环程序依次包含输入映射、步转换、步输出、输出映射等子程序;采用开线程结合Sleep函数实现了PLC定时器功能;给出了实现该顺序功能图的西门子S7-300 PLC主要梯形图程序作为对照,详细描述了其VC实现的步骤和主要代码。采用VC++6.0编程并在PC机上进行了运行调试,通过读取Windows的CPU时间戳的方法对主扫描循环时间进行了测试。研究结果表明,所提出的方法能较好地完成顺序控制功能,扫描时间短,可以满足工业控制要求,具有一定的应用价值。     

顺序功能图在机械手控制设计中的应用

简单介绍了顺序功能图的基础知识，并以机械手控制为例，利用顺序功能图的方法设计其梯形图。与传统的设计方法相比具有简单、直观、逻辑性强等特点，提高了编程的效率。     

编制顺序功能图的技巧与三种实现方法

在《机电设备电气控制系统安装与维护》的理实一体化课程开发中,学生很容易编制一般顺序控制系统的梯形图,但是顺序控制系统的结构变复杂时,自身调试非常不方便且绝大部分学生理不清内在的逻辑性而不能编制出梯形图,达不到机电设备的自动控制要求。针对上述问题,采用FX系列的PLC编程,结合复杂并行序列结构的顺序控制系统实例,首先详尽阐述了顺序功能图(SFC)的组成、动作过程和绘制顺序功能图的注意事项;然后在顺序功能图的基础上,依次使用SFC功能编程、"启保停电路"编程和置位复位指令编程三种方法对结构复杂的顺序控制系统进行编程,为理实一体化课程开发和提高高职院校教师教学水平提供一定的参考价值。     

基于顺序功能图的专用钻床PLC控制系统

介绍了一种法兰盘孔加工专用钻床的工艺过程、执行机构、液压系统、电气控制系统。夹紧油缸把法兰盘定位夹紧在回转工作台上,进给油缸带动动力头实现进退,双钻头动力头旋转钻孔,转位油缸带动工作台回转,完成工位变换。采用可编程控制器的顺序功能图图形语言设计编程,控制各执行机构按加工要求完成有顺序的循环动作,逻辑关系清楚,程序可读性好.并指出了使用顺序功能图进行电气控制系统设计应注意的事项。     

PLC顺序功能图解释程序研究

以烟厂的制丝车间的集控系统中的辅联设备的控制系统为实际案例,实现了在西门子1200PLC中按照顺序功能图流程编程的方案,解决了顺序功能图在1200PLC中的数据结构存贮问题和数据驱动下的解释程序开发,为这类问题提供一个统一的解决方案。     

顺序动作回路

顺序动作回路是实现多个执行元件以动作的回路。按其控制的方法不同可分为压力控制、行程控制和时间控制。压力控制顺序动作回路是用油路中压力的差别自动控制多个执行元件先后动作的回路。压力控制顺序动作回路对于多个执行元件要求顺序动作,有时在给定的最高工作压力范围内难以安排各调定压     

微型计算机顺序控制器

本文提出一种微计算机顺序控制器的工作原理。它具有功能强、程编方便、工作可靠的特点。若利用此原理,并用CPU和少量的RAM和EPROM或者用单片微计算机实现顺序控制,将使这种顺序控制器具有相当高的功能价格比。     

关于行程阀控制的顺序动作回路讨论

关于行程阀控制的顺序动作回路讨论张建栋常见的液压教科书中，行程阀控制的顺序动作回路如图１所示。工作原理是要实现如图２所示的工作循环。但在一般情况下，它并不能实现这个工作循环，而只有在极特殊情况下，才能实现这个工作循环。负载压力、行程阀位置、撞块长度、...     

Optimized sequential design of two-dimensional tolerances

Tolerancing has great impact on the cost and quality of a product. Previous research essentially focussed on one-dimensional tolerancing where sized tolerances accumulate only in one direction. When sized and angular tolerances are considered simultaneously, tolerances accumulate, however, in two different directions in the given view plane. We utilize related tolerance zones to illustrate the accumulation processes of sized and angular tolerances. The orientational tolerances are converted into the equivalent sized or angular tolerances in terms of their engineering semantics. We establish the sequential linear optimization models to maximize the 2D sized, angular, and orientational working tolerances of a 3D machined part based on the process capabilities. At any completion stage of operations, we measure the processed sized dimensions and then substitute them into the dimensional chains to dynamically re-calculate the mean working dimensions for remaining operations. We also re-evaluate the working tolerances for remaining operations using sequential optimization models. This approach can release the working tolerances, reduce manufacturing costs, and enhance the acceptance rate of machined parts when we manufacture the complex, low-volume, and high-value-added parts. The approach is finally illustrated with a practical example.     

分层顺序测试优化方法研究

针对复杂层次系统的故障隔离问题.提出了一种分层顺序测试优化方法.首先基于层次系统故障与测试之间的关联关系,以及故障与不同层级可更换单元的隶属关系,结合故障的先验概率与可用测试成本,构造了层次系统故障隔离问题的数学描述模型;然后以信息增益为启发策略,提出了一种准多步前向搜索算法,实现了不同隔离级的测试顺序优化.经某型卫星电源系统试验验证结果表明,该方可显著提高层次系统的故障隔离效率.     

基于时序模式挖掘的故障诊断方法

为发现生产过程中的故障传递和相互影响规则,并用于故障诊断,在监测系统的时序数据分析中引入序列挖掘技术,提出了采用基于核密度估计的符号空间划分方法,利用数据本身的分布特性对连续数值形的时序数据进行符号化,得到适于挖掘的符号序列.通过故障时窗约束、序列集成和序列化简,将多维非同步时间序列转化为与故障相关的序列数据库.在此基础上,采用序列模式挖掘算法对Tennessee-Eastman仿真数据进行序列挖掘,得到了以时序模式表示的故障过程的主要变化信息.实验表明该方法足可行且有效的.     

分布式环境下全局序列模式挖掘技术研究

由于分布式环境下挖掘全局序列模式常常产生过多候选序列,加大了网络通信代价.为此提出一种基于分布式环境下的全局序列模式快速挖掘算法.该算法将各站点得到的局部序列模式压缩到一种语法序列树上,避免了重复的序列前缀传输;基于合并树中节点序列规则和简单的特点,提出一种项扩展和序列扩展剪枝策略,有效地约减了候选序列,减少了网络传输量,从而快速生成全局序列模式.理论和实验表明,在大数据集环境下该算法性能优越,能够有效地挖掘全局序列模式.     

Plane strain extrusion by sequential limit analysis

In this paper, the analysis of plane strain forward extrusion through wedge shaped dies is implemented by using a finite element procedure based on a dual (upper bound) formulation. Since the von Mises yield criterion is employed and expressed in an inequality form, stresses do not appear in this upper bound formulation. As a result, neither complicated stress updating nor rigid zone treatment is needed in this approach. The effect of material strain hardening can be incorporated in the analysis by updating local yield stresses stepwise with deformation history. The computed results are first compared with existing analytical solutions in good agreement. Effects of friction, die semiangle, height reduction ratio and material strain hardening on the extrusion load of aluminum are then investigated.     

顺序迭代开发过程建模与仿真

为有效地管理和改进产品开发过程,提出了一种基于奖赏马尔科夫链的顺序迭代过程定量模型.该模型与已有的顺序迭代过程模型不同的是,模型中的返工影响因子不仅作用于直接返工任务的持续时间,而且作用于该返工任务的后续任务,即作用于返工任务的整个剩余时间.一个任务在每个阶段的返工量随着迭代次数的增加而逐渐减少.考虑了不同任务引起的同一任务返工量的不同.为估计开发过程的期望时间,建立了过程时间估计的分析模型和仿真模型,给出了仿真计算算法.以软件测试过程为例,给出了过程时间估计的分析和仿真实验结果,并与其他已有模型进行了对比分析.最后,讨论了模型估计结果产生偏差的可能原因.     

基于差分算法的贴装顺序优化问题求解

元器件取料、贴放顺序是影响印刷电路板(PCB)贴片机工作效率的关键因素之一.针对拱架型多头贴片机建立以时间为研究对象的取料、贴放顺序优化数学模型.给定解的整数编码形式,利用差分算法解决此优化问题.将迁徙操作思想引入差分算法,建立带迁徙操作的差分算法,并给出算法流程及实现方式.通过实验选择差分算法的较佳参数,用两组实验将差分算法、带迁徙操作的差分算法与遗传算法进行比较,实验表明差分算法、带迁徙操作的差分算法能够有效地解决拱架型多头贴片机元器件的取料、贴放优化问题,且优化结果较遗传算法好.     

Conicity error evaluation using sequential quadratic programming algorithm

Form error evaluation plays an important role in processing quality evaluation. Conicity error is evaluated as a typical example in this paper based on sequential quadratic programming (SQP) algorithm. The evaluation is carried out in three stages. Signed distance function from the measured points to conical surface is defined and the cone is located roughly by the method of traditional least-squares (LS) firstly; the fitted cone and the measured point coordinates are transformed to simplify the optimal mathematical model of conicity error evaluation secondly; and then optimization problem on conicity error evaluation satisfying the minimum zone criterion is solved by means of SQP algorithm and kinematic geometry, where approximate linear differential movement model of signed distance function is deduced in order to reduce the computational complexity. Experimental results show that the conicity error evaluation algorithm is more accurate, and has good robustness and high efficiency. The obtained conicity error is effective.     

Quantitative image analysis: applications using sequential transformations.

The theoretical foundations of quantitative image analysis and its implementation in the Leitz T.A.S. have been discussed in the preceeding paper [4]. Especially the Mathematical Morphology and its recent developments have been pointed out. Sequential image transformations are a new approach of morphological analysis. Elementary transform steps, which are hardwired in the device, performed in specific sequences, which are implemented as macroinstructions in the programming language have proven to be a very useful tool in image analysis. A specific sequence of elementary steps will be referred to as morphological function. This new approach will be illustrated by four general examples: analysis of fibers, computing the number of edges for metallic grains, separation of overlapping cells, analysis of minerals which occur free and locked to another one.     

Estimation of tissue layer level by sequential morphological reconstruction

An automated method for labelling layers of clustered elements in two dimensional images based on morphological operations is presented here. Unlike the various distance transforms for regular lattices, the procedure deals successfully with clusters composed of different shaped and sized elements and provides a distance measure, in number of layers, from each element in the cluster to any other reference element (or elements). The method was applied to histological sections of two different types of polystratified epithelia. Local clusters in the different cell profile layers can subsequently be used to define the orientation of the tissue layers relative to each element in it.