并联机床后置处理器的开发及实验研究

以六自由度6-TPS型并联机床为模型，阐述了机床控制数据的生成原理和流程；以此为基础，规划了后置处理器的功能和整体结构。对若干关键技术进行了研究和探讨，包括基于参数化二进制格式的内部数据传输，基于刀轴矢量的笛卡儿空间粗插补算法，三维和二维刀具半径补偿，刀位文件的预处理以及加工代码的词法和语法检查等。最后介绍了利用本系统进行的切削实验，验证了系统的工程实用性。     

浅谈并联机床发展趋势

并联机床作为机器人技术、机床结构技术、现代伺服驱动技术和数控技术四者相结合的产物,其发展前景非常广阔。并联机床于1994年在美国芝加哥国际机床展览会上的首次面世标志着机床设计开始采用并联机构,成为机床结构重大改革的里程碑。本文简要介绍了现阶段对并联机床的基本研究和其亟待解决的问题,以及并联机床未来的发展趋势。     

并联机床的设计简述

并联机床是90年代中期问世的新型数控加工设备,是安装刀具的动平台由多个支链联结到固定平台,通过这些支链上的主动副驱动平台运动以改变刀具在空间的位置和姿态,从而实现刀具对工件的进给运动.对并联机床的设计,主要从以下几个方面作简要的介绍:概念设计、运动学设计、力学问题、精度设计与运动学标定、数控系统、关键基础件.     

并联机床研究趋势及我国发展现状分析

并联机床是一种完全不同于传统机床的新一代机床,目前国内外对并联机床的研究趋势主要集中在并联机床机构学理论及相关理论研究、并联机床精度和可靠性研究、并联运动机床开放式数控系统的研究、并联机床组成标准模块和关键基础件的研制等。我国较早地对并联机床进行了研究并取得了较为显著的成果。     

基于CATIA平台的板料成形后置处理系统

基于CATIA平台和CAA二次开发技术,开发了完全集成于CATIA的后置处理系统,采用CATIA可视化显示技术与动态响应技术,实现了视图显示和查询功能。该系统可以在CATIA上直观地反映数据结果,并采用动态存储提高显示速度,操作简单,有效地提高了设计效率,在CATIA平台上实现了CAD/CAE真正意义上的无缝集成,适用...     

通用后置处理中生成固定循环加工指令

介绍了在通用后置处理系统中输出各种固定循环加工指令的实现方法。通过对当今主流数控机床编程手册进行研究，设计数控机床特性文件，该文件与刀位轨迹文件，刀具信息相结合就可以输出各类数控机床的循环加工代码。采用相同的实现方法。也可以实现其它数迭机床控制指令的输出。该系统已经在FUNAC，FIDIA，SIEMENS等数控机床进行成功的试验。     

时延估计后置处理算法的应用研究

时延估计是被动声定位的关键技术。受声信号传播起伏、声测量系统误差以及时延估计算法等均能影响时延估计的精度。因此,为了提高目标定位精度,需要对时延估计进行后置处理。本文研究了ba-递推估计后置处理算法在低空飞行武装直升机被动声定位中的应用,给出了典型飞行条件下的仿真结果。结果表明,采用后置处理算法可以有效地改善时延估值的精度。     

基于软件工程的机床控制设计分析

随着人们日益对生产与生活环境适应性的不断提高,最近几年,很多国内外机床制造业企业都在积极研制和探索新型的具有多功能的系统与制造装备,文章从当前在结构技术上,具有突破性进展的并联机床人手,结合并联机构的进给传动机构的实际情况,进行了大量的分析和研究。     

基于并行计算的三自由度并联机床动力学解析模型

基于运动学分析、凯恩动力学方程和数字-符号方法,建立了三自由度并联机床的动力学解析模型.将广义坐标、构件的质量和转动惯量处理为符号量.将动力学模型矩阵的推导问题转化为特定条件下运用运动学和动力学计算公式求解驱动力的问题,由计算机自动生成动力学模型矩阵中的各元素的实时代码.文中引入了一种新的标量矩阵与矢量矩阵的乘法运算,研究了广义坐标和构件的质量对驱动力的影响规律.构造了动力学解析模型的并行算法,节省了计算时间.给出了动力学模型矩阵元素的实时代码生成和驱动力矩与参数关系的具体数值实例.     

基于Pro/E的6-HTS并联机床虚拟样机参数化实体建模

基于平行滑块式6-HTS并联机床的概念机模型,建立了其各个结构部件的参数化实体模型及虚拟样机实体模型装配体。由于虚拟样机的所有部件的实体模型采用的都是真实尺寸而且是参数化的,得到的虚拟样机模型非常逼真。     

An open distributed measurement system based on an abstract client-server architecture

This paper describes in detail a Java-based, client-server architecture specifically designed to allow a flexible management of remote instruments. The main attributes of the proposed solution are portability and extensibility. The former feature is assured by the employment of the TCP/IP protocol suite and by the Java language properties. The latter is due to the high level of abstraction of the system implementation. This approach addresses a wide range of possible applications with high code reusability. In fact, the proposed architecture permits to drive many kinds of different devices and can be easily upgraded simply by adding a limited amount of code on the server computer whenever a new instrument is connected to the system.     

RT-Linux坐标测量机开放式控制系统构建

构建了一种基于RT-Linux操作系统的坐标测量机开放式控制系统.该系统利用RT-Linux作为操作系统.以模块化方式实现了坐标测量机的运动控制、相关I/O控制、测量数据采集和人机界面显示等功能.并且这些模块完全开放,从而使控制系统具有互操作性、可移植性、可缩放性和可互换性,大大提高了坐标测量机控制系统的适应能力.     

Reliability-based maintenance and job scheduling for identical parallel machines

Quality has an important role in manufacturing, and on the other hand, machine condition has a significant effect on quality. Based on this fact, all manufacturers integrate the production scheduling with maintenance activities to keep the machines in perfect conditions. In this paper, we propose a mixed integer nonlinear model to optimise the quality cost, maintenance cost, earliness–tardiness cost and interruption cost simultaneously. We assume that if machines work in undesirable conditions, their quality is reduced, resulting in quality cost. On the other hand, if the machines are repaired to decrease the quality cost, maintenance cost and other cost such as earliness–tardiness cost and interruption cost are imposed to the manufacturer. Several numerical instances are implemented by the proposed model to show the model effectiveness to obtain the best maintenance and production scheduling with minimum quality cost.     

Fast and meta-heuristics for common due-date assignment and scheduling on parallel machines

This study considers common due-date assignment and scheduling on parallel machines. The problem has three decision variables: assigning the common-due-date, allocating jobs to parallel machines, and sequencing the jobs assigned to each machine. The objective is to minimise the sum of due-date assignment, earliness and tardiness penalties. A mathematical programming model is presented, and then two types of heuristics are suggested after characterising the optimal solution properties. The two types of heuristics are: (a) a fast two-stage heuristic with obtaining an initial solution and improvement; and (b) two meta-heuristics, tabu search and simulated annealing, with new neighbourhood generation methods. Computational experiments were conducted on a number of test instances, and the results show that each of the heuristic types outperforms the existing one. In particular, the meta-heuristics suggested in this study are significantly better than the existing genetic algorithm.     

基于PLC的精冲机电气控制系统研究

该文针对目前精冲机的电气控制系统操作复杂、系统抗干扰能力差、电气控制系统和液压系统难以协调工作的现状,给出以PLC为核心控制器件的控制方案,详细阐述控制系统的设计过程,PLC、触摸屏的硬件选择及应用注意事项。实际应用表明:利用PLC实现对精冲机的控制,保证了精冲机各种动作协调、可靠地运行,从而提高精冲机的整体性能。     

Scheduling of unrelated parallel machines: an application to PWB manufacturing

In this paper, we tackle scheduling the bottleneck operation of a Printed Wiring Board (PWB) manufacturing line. The problem may be characterized as unrelated parallel machines and we are interested in several performance measures including: makespan, the average finish time, mean flow time, utilization, the number of lots and the total amount of overtime beyond the release interval. Due to setup reduction techniques employed by the company, setups are negligible, and we construct an Integer Programming (IP) model with a special structure - >unimodularity. Thus, the corresponding linear programming optimal solution always satisfies the integrality constraints. In order to account for multiple objectives of the scheduling system, we introduce preference constraints and bring them into the objective function by Lagrangian Relaxation (LR). We give a heuristic procedure to select constraints to be relaxed, and formulations to determine the Lagrange multipliers. To verify the validity of the proposed method, we compare it with a network model and with a modified FIFO method. The proposed method presents very promising results in terms of our measures of interest.     

基于VRML的空间并联机器人运动仿真优化

虚拟现实技术(VRML)经常被运用于机器人仿真,针对传统的并联机器人运动学反解运算量大所引发的仿真系统效率问题,采用VRML的IndexedLineSet节点,通过负载平台的运动学参数动态更新IndexedLineSet节点,并以该节点为基础解出导杆的位姿.通过JavaScript与VRML交互编程实现了6自由度机器人的运动仿真.结果证明,优化后的系统仿真效率相比于传统的方法有很大的提升.     

Approximation algorithms for common due date assignment and job scheduling on parallel machines

We consider the problem of assigning a common due date to a set of jobs and scheduling the jobs on a set of parallel machines so that the weighted sum of the due date, total earliness, and total tardiness is minimized. A heuristic is developed to solve this problem, and an absolute performance ratio is provided for this heuristic. Another heuristic with a better worst-case performance bound is presented for the case with a zero earliness penalty. A fully polynomial approximation scheme is also developed.     

Error bound for common due date assignment and job scheduling on parallel machines

We consider a heuristic which has been applied to assign a common due date to a set of n jobs and schedule them on a set of m parallel and identical machines so that the weighted sum of the due date, earliness and tardiness is approximately minimized. We alter the heuristic slightly and show that the revised version is asymptotically optimal as n→∞.     

基于MATLAB的3-RPS并联机构控制系统仿真

针对传统螺旋法求解并联机构Jacobian矩阵的缺陷,提出了一种基于并联机构微运动分析的微位移法.该微位移法在求解过程中可避免求解超越方程组的难题,且得到的Jacobian矩阵为非奇异方阵.同时,针对并联机构传统控制器轨迹跟踪精度低的问题,设计了一种基于并联机构动力学方程和比例切换控制律的滑模变结构控制器(SMC).首先,建立机构的MATLAB/SimMechanics仿真分析模型,采用微位移法求解并联机构的Jacobian矩阵,为控制系统提供理论参考输入值.其次,设计SMC控制器,运用Lyapunov函数证明控制器的稳定性;最后,分别建立机构PID控制和SMC控制系统的MATLAB/Simulink框图,对其进行仿真分析与对比.结果表明:SMC控制器的轨迹跟踪精度比PID控制器的精度高,稳态误差小,且鲁棒性强,响应速度快,从而验证了SMC控制的有效性.