Approximate methods for simulation and verification of numerically controlled machining programs

Algorithms for simulation and verification of Numerically Controlled (NC) machining programs are presented. Compared to NC simulation based on conventional solid modeling systems, these models are designed to give approximate results, but with a substantial decrease in computer time. The surfaces of the part are discretized into a Surface Point Set (SPS) with a point spacing dependent on cutting tool size and shape local surface curvature and the desired accuracy of the approximate simulation. The surface-surface intersection calculations of the solid modeling approach are replaced by the intersection of the surface of the tool movement envelope with straight lines emanating from the surface points. The methods are applicable to both 3 and 5 axis machining. Samples test cases are presented, and implementation and efficiency issues are discussed.     

远程数控仿真系统的设计与实现

由于几何建模的复杂性和消隐算法的低效性,目前的数控仿真系统大多只能实现数控加工结果显示,而在数控加工过程实时仿真方面功能还很弱,对于基于Internet的远程数控仿真的研究则更少。为解决以上问题,提出了实现远程数控仿真的技术框架,即采用VRML建立几何模型,采用Java建立通信接口,构造虚拟环境与操作者之间的通信机制。通过构造EAI接口控制Eleva-tion Grid结点,实现工件动态建模,采用Java applet构造NC代码解释器,并阐述了干涉校验的实现方法。实现了远程数控仿真系统。     

改进的八叉树模型在3D刀轨显示系统中的应用

在传统的八叉树模型的基础上增加了扩展八叉树结点,同时引入了混合式的八叉树教据结构,并将它们应用到数控加工的三维刀轨显示系统中;叙述了实体从B-rep表示法转换为相应的改进型八叉树模型的方法,并在这种改进的八叉树模型的基础上完成对零件加工过程的实时性仿真;最后通过运行实际的数控加工程序证明该算法的可行性和有效性.     

Solid modeling of 4-axis wire EDM cut geometry

NC verification has been widely used in milling and turning machining, but the implementation of NC verification for wire electrical discharge machine (wire EDM) has received little attention, made difficult by the characteristics of geometry cut by the thin wire. For an NC verification system, the speed and the accuracy of are two of the most critical issues. In this paper, a novel solid modeling method, which utilizes a dual quadtree structure and a boundary representation, is applied to modeling the parts cut by a wire EDM. In this implementation, two extended quadtrees on the top and bottom surfaces of the stock are first created. Special quadtree nodes are introduced into the dual quadtree structure to model the features associated with the almost coincident surfaces left by a thin wire. The region swept by a wire in each move is generated based on the diameter of the wire, spark gap size and the paths. The overall geometry of the part is represented by a boundary representation which is updated by means of efficient Boolean operations of extended quadtrees. The free-falling objects which may damage the machine tool can be detected. Dimensional inspection and feature detection can be made with the solid model representing the machined part. The system has demonstrated very promising speed and accuracy.     

An algorithm for converting the boundary representation of a CAD model to its octree representation

Present CAD systems store the solid model of an object using a convenient representation. Boundary models and CSG (Constructive Solid Geometry) models are the most frequently used representations. Based on recent research findings, octree representation of an object presents a promising approach in solving problems in the areas of Computer Graphics, Manufacturing and Robotics. The most notable use of octree representations is in CAD-based robotic path planning problems. Octree models have also been used in fast rendering of 3-D solid models using ray tracing methods. This paper presents an algorithm for converting the boundary representation of polyhedral models to its octree representation. Such an algorithm would provide the link between an object generated using a solid modelling system and the application involving an octree representation of an object. The algorithm is demonstrated by converting a polyhedral boundary model of a sample object to its octree representation.     

离散信号事件驱动的自动测试系统仿真验证方法与实现

为在设计早期对复杂自动测试系统进行充分验证从而加速其成熟并降低研发成本,对离散事件系统规范进行扩展和改进,在原子模型中引入了端口和故障模式,通过端口间的连接构成耦合模型,提出一种离散信号事件驱动的仿真调度算法,并给出一个C/S架构的支持远程交互的仿真验证实现方案;基于自研的SCATS自动测试系统软件平台,分别针对一个示例系统和真实系统开展了实验,结果表明所提模型和方法支持复杂系统多分辨率层次化建模,仿真具有较高的一致性和执行效率,满足自动测试系统仿真验证工程应用需求。     

A flexible quantitative method for NC machining verification using a space-division based solid model

A geometric-modeling method called Graftree and a system design of an NC (numerical control) machining verifier based on Graftree are proposed. Graftree is constructed by combining Oct-tree and constructive solid geometry (CSG) so as to simulate machining processes precisely in three-dimensional space. Using Graftree, the Boolean operation produces no risk of yielding topological conflicts, which often cause the simulation to stop abnormally. Based on the properties of Graftree, an NC machining verifier is designed to consist of three individual subsystems: data-input operations, geometric simulation, and interactive verification, i.e., visuluatzation of machining scenes and evaluation of the machined product using models of the measuring instruments. This design lets the users watch selectively only the machining steps they want to check precisely, and verify the machining according to dimensional tolerance.     

三维虚拟加工环境及其关键技术的研究

在分析虚拟制造特点的基础上,提出了三维可视化虚拟加工环境的系统结构,介绍了支持三维建模仿真的组件设计、基于装配模型的三维实体建模方法、NC代码解析器的设计方案以及基于毛坯表面三角片离散化的加工过程仿真算法,并开发了虚拟加工环境原型系统,该系统能够实时地反映零件虚拟原型的加工成形过程仿真,并进行可加工性分析。     

Octree Representation and Its Applications in CAD

In this paper,a survey of octree representation and its applications in CAD is presented.The octree representation may be categorized as pure octree representation and polytree(or extended octree),and the latter is actually a boundary representation decomposed by octree.Linear octree which is a variant of regular octree representation has the advantage of saving memory space.The mapping between Cartesian coordinates and node addresses in linear octree is discussed.Then,algorithms for converting a boundary representation of 3D object into an octree are investiged and major approaches for transforming an octree encoded object are presented.After that,some of the applications of octree representation in CAD are listed,in particular,the applications in solid modeling,in accelerating ray tracing and in generating meshes for FEM.     

基于事件图的离散事件仿真模型并行检验方法

非形式化仿真模型验证方法易受主观因素的影响且具有不完备性,而传统的形式化模型检验方法由于受到状态空间爆炸问题的影响,很难处理大规模的仿真模型.并行模型检验方法以其完备性、高效性已经在工业界中得到了成功的应用,但是由于涉及到形式化规约、逻辑学以及并行计算等多项技术,应用难度较大.针对上述问题,提出了基于事件图的离散事件仿真模型并行检验方法.该方法首先对事件图在模型同步方面进行了扩展,给出了扩展事件图的形式化定义、语法及语义;然后将扩展事件图模型转换到分布并行验证环境的DVE模型,成功地将并行模型检验方法应用于仿真模型验证领域.该方法使得仿真人员无须学习新的形式化验证语言就能采用并行模型检验方法对仿真模型进行形式化验证,可降低模型并行验证的难度,从而有效提高模型验证的效率和完备性.实验结果表明了该方法的有效性,有利于扩展并行模型检验方法在仿真领域中的应用.     

某型机载雷达对抗仿真训练系统的分析与设计

本文研究某型雷达对抗仿真训练系统的分析与设计两个方面问题.为了解决大型仿真系统联邦成员多且建模困难问题,围绕某型机栽雷达对抗仿真训练系统建设,应用面向对象技术分析系统,提高系统体系结构模型的健壮性和可扩展性.为了进一步提高系统的可重用性,解决联邦成员设计中普遍存在紧耦合性问题,应用用软件模式设计了一种基于仿真逻辑的组件...     

基于面向对象的虚拟数控系统的研究

提出了虚拟数控机床的基本系统结构,引入面向对象程序设计的基本概念于虚拟数控机床的设计.根据数控机床各零部件在加工过程中的特点,把它们分成静态类、运动类和动态类3类.在此基础上,利用3维实体CAD（computer aided design）软件系统进行虚拟数控机床加工过程中非变形物体（静态类与运动类）的外形设计并转换成STL（stereolithography）文件,对动态变形物体采用特征造型方法,与设计的成员函数即该零部件的运动函数有机地集成起来,构成类,最终实现数控机床各机构的动态仿真.引入了四元数的基本概念,并将其应用于系统设计与实现.上述方法为虚拟数控系统的研究提供了基本框架.实验结果证明,上述方法是可行的,具有很好的实用价值和参考价值.     

基于STeC-Stateflow转换系统的实时系统仿真与验证方法

物联网以及信息物理融合系统对形式化建模提出了新的挑战, 引入了实时系统规范语言STeC, 为刻画实时系统的时空一致性提供了规范语言。针对STeC语言建立STeC至Stateflow自动转换系统, 提出一种基于STeC至Stateflow转换的仿真及验证方法, 该方法使用STeC语言对实时系统进行形式化建模, 再建立实时监控的Simulink仿真模型, 并使用Checkmate对系统进行安全性验证。通过对京沪高铁运行的实例研究, 表明该方法对高铁运行系统实时仿真的有效性, 并能够验证高铁运行系统的安全性。     

基于虚拟样机的仿真系统校核、验证与确认研究

虚拟样机模型的正确性和精确度直接影响到仿真的置信度,如何保证建立的计算机仿真模型的正确性是虚拟样机建模的一个重要问题。首先对虚拟样机技术的特点及其仿真步骤进行了描述;然后,在介绍仿真系统校核、验证与确认概念的基础上,讨论了分布交互仿真系统校核、验证与确认的原则;根据虚拟样机的特点,研究制定了虚拟样机仿真系统的校核、验证与确认的七步过程,重点对虚拟样机仿真系统的模型验证方法进行分析;最后,提出了的虚拟样机校核、验证与确认过程中应该遵循的原则。     

某飞机辅冷系统IMA应用实时验证模型研究

某飞机环控增加蒸发制冷式辅助冷却系统(简称辅冷系统),对多个厨房、大功率电子设备以及设备舱进行冷却。为了对综合模块化航空电子系统(IMA)驻留应用进行硬件在环(HIL)测试验证,开展辅冷系统实时仿真模型研究。在对辅冷系统冷凝器等关键部件的建模原理进行数学描述后,利用MATLAB/Simulink进行部件建模与仿真分析,并根据建模框架对辅冷系统模型进行集成与仿真,最后将模型下载到实时机对IMA应用进行HIL测试。仿真与测试结果表明,制冷剂工作压焓曲线满足要求,辅冷系统模型仿真误差满足要求,可以对IMA应用进行实时的仿真验证。首次利用模型开展制冷剂在关键部件的工作压焓曲线以及飞机辅冷全系统的HIL测试研究,该研究对制冷领域的系统级实时仿真验证具有参考意义。     

An environment for DEVS-based multiformalism simulation in Common Lisp/CLOS

The paper presents the realization of an object-oriented kernel of a new modeling and simulation environment. The kernel system stands out as it is based on systems theoretical concepts and facilitates combined discrete-continuous, modular, hierarchical modeling. Its implementation language is the AI language Common Lisp and its object-oriented superset CLOS. The kernel system serves as the basis for a knowledge-based modeling and simulation environment supporting interactive modeling and simulation and automatic model construction. This research was supported in part by SIEMENS Munich, ZFE, ST.     

A rule-based parametric modeling method of generating virtual environments for coupled systems in high-speed trains

A rule-based parametric modeling (RPM) method is proposed to dynamically generate virtual environments for simulation and analysis of the dynamics of coupled systems in high-speed trains. First, a precise and complete basic-element model base is built according to the modeling requirements of virtual simulation environments. Meanwhile, the classes of and relationships between the basic-element models are defined with respect to the geometrical, topological, semantical and appearance properties of these models. Then, multi-level semantic constraint rules and a parametric modeling method are designed to accurately analyze the simulation parameters and to rapidly integrate various basic-element models for automatic generation of virtual high-speed railway environments. Finally, after a prototype system is developed, various experiments are carried out for analysis of the advantages of the RPM method. The experimental results show that the RPM method can be used to normalize the error-prone modeling procedure and rapidly generate precise and realistic virtual environments.     

基于XML的信息物理融合系统组件建模与仿真

信息物理融合系统（CPS）涉及多种计算模型的集成和协同工作，针对CPS设计方法不统一、重塑性差、复杂度高、难以协同建模验证等问题，提出一种结构化、可描述行为的异元组件模型。首先，用统一组件建模方法进行建模，解决模型不开放问题；然后，用可扩展标记语言（XML）规范描述各类组件，解决不同计算模型描述语言不一致和不可扩展问题；最后，用多级开放组件模型的协同仿真验证方式进行仿真验证，解决验证的不可协同问题。通过通用组件建模方法、XML组件规范描述语言以及验证工具平台XModel对医用恒温箱进行了建模、描述和仿真。医用恒温箱的案例表明，这种模型驱动建立可重塑异元组件并确认其设计正确性的过程，支持信息物理协同设计和边构建边纠正，可避免在系统实现过程中发现问题时再进行反复修改。     

基于FPGA的计算机系统原型仿真平台设计

如何帮助学生实现认知上从理论到实践的飞越,是传统计算机体系结构教学面临的最大挑战.目的是构建可重构的计算机系统原型仿真实验平台,给学生创造一个设计计算机系统原型的机会.通过FPGA仿真验证和C语言模拟器仿真的方法,以32位乱序流水线的RISC处理器原型为核心,构建了C语言模拟器、RTL仿真器和FPGA仿真验证平台,移植和改造了操作系统、编译器等系统软件和工具链,最终设计和实现了一套完整的计算机系统原型仿真教学实验平台.仿真教学实验平台与目前传统的计算机系统教学实验平台相比,具有较先进的技术水平,并具有开放性,可扩展性,综合性的特点,易于在教学中使用.     

COLLISION DETECTION AMONG MOVING OBJECTSIN MACHINING PROCESS SIMULATION

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