Virtual Computer Numerical Control System

This paper presents a comprehensive virtual simulation model for CNC systems. The Virtual CNC (VCNC) has a modular architecture, allowing a real CNC to be prototyped quickly from standard library functions for feed drive models, feedback devices, axis control laws, and trajectory interpolation. Additional CNC modules can easily be prototyped and integrated to the VCNC by the user. Various application examples are presented which include the prediction of contour errors, auto-tuning of feed drive controllers, toolpath and feed modification for improved cornering, and rapid identification of closed loop drive dynamics. Detailed experimental verification is presented for each algorithm.     

Rapid identification technique for virtual CNC drives

This paper presents a technique for rapid identification of machine tool drives by conducting a short G-code test. The proposed strategy uses commanded and measured axis profiles and requires minimal intervention to the servo control loop. The drive system is identified as a whole, including the feed mechanism, motor, amplifier, and the control law. The methodology is fairly general and applicable to linear or ball screw drives, controlled with commonly used controllers like P, PI, PID, P–PI Cascade or Adaptive Sliding Mode Control; with or without feedforward dynamic or friction compensation. In order to guarantee the stability of identified dynamics, bounds are imposed on the pole locations. The identified models can be used in a Virtual CNC system for predicting the contouring and tracking errors to different part programs. Simulation and experimental case studies are presented, where tracking and contour errors are successfully predicted using drive models identified with the proposed strategy.     

3-RRR平面并联机器人神经网络滑模控制研究

针对具有强耦合和高非线性并联机器人的轨迹跟踪控制研究,设计了一种基于神经网络滑模控制器的控制系统。在传统滑模控制的基础上,利用神经网络算法实时修正系统非线性项和不确定参数的功能,有效抑制了SMC系统的抖振现象。建立了3-RRR平面并联机器人的结构简图和Matlab模型,并采用闭环矢量法得到了机器人的运动学反解,为控制系统提供了参考输入。基于机器人的简化动力学方程,设计了一种RBF神经网络滑模控制器,并构造Lyapunov函数证明控制器的稳定性。分别采用传统滑模和神经网络滑模控制方式对机器人的轨迹跟踪进行仿真分析。仿真结果表明:神经网络滑模控制器具有更好的轨迹跟踪精度和较小的稳态误差,验证了神经网络SMC控制器的有效性。     

基于MATLAB的并联机器人ISMVSC轨迹跟踪控制研究

主要介绍了积分滑模变结构控制（ISMVSC）在并联机器人控制系统中的应用。在传统变结构理论的基础上。提出一种以趋近率设计的ISMVSC模型跟踪控制策略,并将此理论应用于两自由度并联机器人轨迹跟踪控制系统。基于MATLAB／SIMULINK进行动态仿真,仿真结果表明：ISMVSC控制策略对外部干扰及参数变化具有较强的鲁棒性,其良好的跟踪性能可实现并联机器人的高精度控制。     

Virtual CNC system. Part II. High speed contouring application

This paper presents a trajectory planning strategy for maintaining the tool positioning accuracy in high speed cornering applications. A 3D contour error estimation algorithm is presented for determining the geometric deviation from arbitrarily shaped toolpaths. Two spline fitting strategies are developed for smoothening sharp corners. The under-corner approach reduces the toolpath length, and therefore the cornering time. This technique yields successful results when used with a high bandwidth servo controller (such as sliding mode control), capable of accurately tracking the commanded toolpath. The over-corner approach is based on stretching out the sharp corner with a smooth curve, which counteracts the ‘undercut’ caused by the large phase lag in low bandwidth servo controllers (such as P–PI control). The cornering feedrate is adjusted in the Virtual CNC platform, developed in the first part of this article, to ensure that contour error violation does not occur. The achieved cornering accuracy is verified in experiments, which are in close agreement with predictions obtained with the Virtual CNC.     

凸轮轴数控磨削系统的程序实现

文章介绍了在基于IPC和Windows平台下,摇摆式凸轮轴数控磨削系统的实现方法.同时对CNC系统的控制技术、实时中断的获取方法、虚拟设备驱动程序(VxD)、VtoolsD工具开发包以及应用程序与VxD之间的通信机制作了简要介绍.通过对源代码的分析说明了摇摆式凸轮轴数控磨削系统的实现过程.     

基于滑模控制的活塞式压力模拟装置位置伺服系统设计

为解决活塞式压力模拟装置位置伺服系统速度可控、位置接近段运动平稳的问题,选用滑模变结构控制设计永磁同步电机位置伺服系统。分析现有变结构伺服系统中位置速度一体化控制设计的思想和方法,提出一种简化的滑模控制器设计方法,该方法通过滑模面状态量的简单切换,就可以实现速度控制和位置定位,具有结构简单、实现方便的特点。仿真结果验证了该滑模控制器设计方法的正确性,最后通过实验平台进行压力模拟实验,实验结果表明该滑模控制的位置伺服系统设计可行有效。     

基于IEC61499标准的可重构数控系统设计方法

可重构数控系统采用模块化结构和开放式系统接口,可充分利用先进的控制技术、硬件产品等有利资源,提高系统功能的自适应性与快速响应能力.根据制造技术不断变化的发展要求,通过对IEC 61499功能模块模型进行研究,提出了一种控制逻辑可重构的数控系统设计方法,规范软件功能模块的接口信息与控制算法描述,提高系统功能的升级、集成与二次开发能力.为了验证所提出的设计方法,搭建了可重构数控系统的基本原型,并进行加工测试.     

SIEMENS 840D数控系统渐开线插补指令的应用研究

CNC机床在加工零件的过程中，轴的运动轨迹是由数控系统的插补功能完成的。随着CNC的不断完善和发展，其中的渐开线插补应用场合越来越广泛。SIEMENS840D数控系统的渐开线插补功能强大，种类多，可以解决生产中的很多问题，因此得到了越来越广泛的应用。文章首先介绍了西门子SINUMERIK840D的渐开线插补指令，在此基础上通过一个工程实例-电缆弯制过程并结合Matlab的计算功能研究、展示了SIEMENS840D渐开线插补功能。     

CNC系统中"S曲线加减速"规划算法的研究与实现

速度控制、位置控制、多轴联动、直线插补和圆弧插补等是开放式CNC(Computer numerical control)系统的关键技术。运动过程中的升降速控制是高档CNC系统开发中的一大技术难题。优良的升降速控制能在很大程度上提高加工精度。对S曲线加减速算法进行了深入的理论和应用研究,通过该算法使系统的速度变化尽可能的平稳,实现系统加减速的柔性控制,减少对电机的冲击,延长整个系统的使用寿命。应用于工业PC、基于TMS320LF2407A的运动控制器、Lexium17D伺服驱动器和伺服电机组成的伺服系统中,其效果明显优于“梯形曲线加减速”。     

基于WinCE7和WiFi的数控转塔冲床数控系统无线通信的实现

通过分析基于PC的传统开放式数控系统的缺陷,提出一种基于高实时性、多任务的嵌入式操作系统WinCE7和CORTEXA8微处理器的数控转塔冲床数控系统,WinCE7操作系统是一个紧凑高效的模块化操作系统,配合CORTEXA8微处理器能满足数控转塔冲床对实时控制的要求。分析了计算机与数控机床之间通信方式的发展趋势和对机床加工高效化、自动化的影响,提出基于WiFi的数控转塔冲床无线通信解决方案。实验结果表明:WiFi模块工作正常,能实现上位机与嵌入式控制器之间的数据收发,降低了成本,提高了效率。     

Machining contour errors as ensembles of cutting, feeding and machine structure effects

CNC machining has been studied from the perspective of either cutting or feeding. However, machining quality is the outcome of both of these processes. This work investigates the contour errors of a complete CNC machine system. A system model is developed to cover all groups of functions, including trajectory planning, trajectory tracking, cutting process and machine structure. Analysis results reveal the limitations of traditional studies. The dependence of contour errors on trajectory curvature, feed-rate, cutting depth and tracking control is investigated as well. A new model of CNC machining is developed.     

六轴联动电火花加工数控系统及机床

针对闭式整体涡轮叶盘的特殊加工要求,充分利用六轴联动所能提供的空间可达性．提出并实现了一些专门用于加工闭式涡轮叶盘的特殊功能,旨在大幅提高系统的加工效率与精度。降低加工成本。基于开源操作系统与可编程运动控制器,开发了六轴联动电火花加工数控系统．用于控制3个移动轴和3个回转轴的同时插补。该系统包括连续平滑的空间曲线路径及电极空间姿态角的六轴联动单位弧长增量法直接插补技术、曲线路径的六轴联动伺服进给与回退技术、曲线路径的六轴联动抬刀技术等。六轴联动极大地提高了加工柔性与自由度。使该系统可用于更多类型、更复杂曲面的加工。     

精密辊筒机数控系统开发

针对自主研发的精密辊筒机床,开发一套基于IPC和UMAC的开放式数控系统。依据精密辊筒数控机床的功能需求和结构特点,设计数控系统的硬件平台,搭建数控软件的总体框架,并采用模块化编程技术,基于Qt Creator编程环境开发数控系统软件,实现了轴信息显示、运动控制、自动编程和程序编辑等功能。进行微V形槽阵列加工实验,结果表明:该数控系统功能丰富,运行稳定,可以满足精密辊筒机床的数控加工要求。     

基于USB总线的微型车床开放式数控系统研究与设计

针对微型车床数控加工系统,提出并初步实现了一种便捷的基于USB总线的开放式数控系统。开放式数控系统由上位机和STM32+FPGA组成的下位机构成。研究了数控系统实时多任务调度,译码、刀补、插补算法的软件实现,针对微型车床研究了下位机的功能要求并设计了硬件电路板,研究了下位机的内存管理及运动控制的实现。提出了一种基于USB串行总线的通信方式,验证了USB在开放式数控系统中的可行性。实验证明,USB总线可以便捷高效地运用在开放式数控系统中;通过软硬件结合的方式,保证了系统具有良好的开放性、实时性和同步性。     

基于SolidWorks的组合夹具CAD系统的开发

文章针对西安昆仑机械厂提出的数控机床用的组合夹具,常因生产时间交替,造成对同一零件,其组合夹具结构和安装方位差异较大,从而使编好的数控加工程序不能直接重复使用的问题,以SolidWorks为平台,建立了组合夹具CAD系统.该系统运用SolidWorks面向对象的参数化特征造型方法和成组技术原理,建立组合夹具元件库和对组合夹具进行分类、装配、管理.该系统的建立对组合夹具的推广,CAD/CAM的集成,有一定促进作用.同时,作者借助VC 6.0和SolidWorks的API函数对SolidWorks的二次开发进行了有益的探索.     

High speed CNC system design. Part I: jerk limited trajectory generation and quintic spline interpolation

Reference trajectory generation plays a key role in the computer control of machine tools. Generated trajectories must not only describe the desired tool path accurately, but must also have smooth kinematic profiles in order to maintain high tracking accuracy, and avoid exciting the natural modes of the mechanical structure or servo control system. Spline trajectory generation techniques have become widely adopted in machining aerospace parts, dies, and molds for this reason; they provide a more continuous feed motion compared to multiple linear or circular segments and result in shorter machining time, as well as better surface geometry. This paper presents a quintic spline trajectory generation algorithm that produces continuous position, velocity, and acceleration profiles. The spline interpolation is realized with a novel approach that eliminates feedrate fluctuations due to parametrization errors. Smooth accelerations and decelerations are obtained by imposing limits on the first and second time derivatives of feedrate, resulting in trapezoidal acceleration profiles along the toolpath. Finally, the reference trajectory generated with varying interpolation period is re-sampled at the servo loop closure period using fifth order polynomials, which enable the original kinematic profiles to be preserved. The proposed trajectory generation algorithm has been tested in machining a wing surface on a three axis milling machine, controlled with an in house developed open architecture CNC.     

KC-TZ118型链轨节数控钻镗组合机床的研制

KC-TZ118型链轨节数控钻镗组合机床,是校企合作共同研发的高效率、高精度、高性能自动钻镗组合机床,专门用于挖掘机左右链轨节镗孔、钻孔的加工.主要介绍KC-TZ118型链轨节数控钻镗组合机床的方案确定、机床结构特点、机床参数的配置、数控系统的配置及调试方法等,并详细分析机床设计中的关键技术.     

基于PMAC的开放式弧焊机器人控制系统

针对V01弧焊机器人控制器结构封闭，不能进行离线编程和集成焊接传感器的缺点，设计了一种基于PMAC的开放式机器人控制器。文中给出了控制器分层的系统体系和结构化的功能单元组成的控制系统体系结构，根据该体系结构设计了机器人的伺服系统和控制器的硬件结构；采用面向对象技术和模块化的思想开发了系统的控制软件。     

基于DSP运动控制器的实时多任务开放式数控系统

文章在对CNC系统进行面向对象分析的基础上,建立了以PC机作为上位机、DSP运动控制器作为下位机的主从式数控系统.以C BUILDER为开发工具,采用模块化结构设计,体现了数控系统开放性的基本思想.