一般零件参数化绘图的实现

对于一般零件，因其在机器或部件中的功用不同且具有不同的结构和形状，不宜采用参数化绘图。传统的绘图方法是利用AutoCAD的绘图和编辑功能，通过频繁地点击鼠标、敲击键盘来输入命令、数据绘制图样。以AutoLisp为开发工具，通过建立基本图形程序库，实现一般零件的参数化绘图，简便、快捷，使绘制零件图向自动化方向迈进了一步。     

利用Autolisp及DCL语言建立机械零件图形库

利用Ａｕｔｏｌｉｓｐ和ＤＣＬ语言进行二次开发，建立了机械零件图形库，在绘图过程中直接调用，实现机械图形的快速绘制     

基于AutoLISP语言参数化绘图的实现

在绘制机械零件图时,经常遇到绘制标准件、中心孔等常用图形的烦琐工作。AutoCAD中提供的块操作命令BLOCK及块写出命令WBLOCK,可以将常用的某一图形写成块,然后利用INSERT命令进行插入,即可避免重复绘制某一常用图形,但使用这种方法只能按比例对图形进行缩放,无法实现参数化变化。 所谓的参数化绘图,是将工程图中的图形与一组参数相关联,由这组参数表示的约束条件来确定相应的零部件图形,即根据参数生成图形或修改已有图形的参数后进行图形更新。本文介绍的是在AutoCAD软件中,利用AutoLISP语言开发具有参数化绘图功能的程序,图形绘制过程中所有尺寸的     

快捷、适用的计算机绘图（二）

三、计算机绘制零件图 用计算机绘图与用手工绘图在方法和步骤上没有本质的区别,但在具体操作上,需要我们熟练并灵活运用计算机绘图系统提供的各种绘图工具。 计算机绘图的基本过程包括: (1)设定图幅、比例,调用边框、标题栏。 (2)绘制并编辑图形。     

计算机CAD绘图的基本方法和应用技巧探析

随着各行业广泛运用CAD作为绘图工具,其绘图的基本方法、应用技巧以及图形绘制习惯越来越受到业内人士的重视。本文针对计算机CAD绘图中的基本方法、绘图技巧以及绘图习惯的重要性进行探析。     

浅析AutoCAD二维绘图中常用的几种技巧

总结并介绍了AutoCAD二维绘图中常用的技巧,包括绘制倾斜图形技巧、二维面域造型法、复杂圆弧连接、均布及对称图形绘制技巧、快速获得工程图标准绘制设置等,为准确绘制图样、提高绘图效率,提供了新的思路。     

基于AutoLISP语言参数化绘制锥体排版图

AutoLISP语言参数化绘制锥体排版图是将工程图中的图形与一组参数相关联,由这组参数表示的约束条件来确定相应的零部件图形,即根据参数生成图形或修改已有图形的参数后进行图形更新。本文利用AutoLISP语言开发具有参数化绘图功能的程序,图形绘制过程中所有尺寸的计算、位置的确定以及尺寸标注等完全由编制的程序来执行。绘图时,只需输人参数,由应用程序自动生成符合要求的图样。     

"互联网+"AR技术、AutoCAD与机械制图理论结合的课程教学改革——评《现代工程图学》

机械制图是高等工科院校机械类和近机械类专业的一门必修专业基础课,既有理论性又有很强的实践性.机械制图研究绘制和阅读工程图样的原理和方法,在工程学科的人才培养体系中占有重要地位.AutoCAD计算机绘图是利用计算机对数值进行处理、计算,从而生成所需的图形信息,并控制图形设备输出图形,以实现图形和数值之间的转换.AutoCAD具有强大的图形绘制功能、图形编辑功能和图形输出功能,绘图效率高、绘图准确度好、绘图强度低,已经代替大部分的手工绘图工作,帮助工程技术人员完成从设计到绘图的一系列工作.     

三牙轮钻头参数化绘图系统的研究与开发

以AutoCAD 2006为图形支撑平台,采用可视化界面思想和ActiveX Automation技术,利用内嵌于AutoCAD的VBA语言进行编程,并结合图形数据库技术,开发了三牙轮钻头CAD参数化绘图系统,实现了三牙轮钻头图形的参数化绘制,可有效提高三牙轮钻头的绘图质量和设计效率.     

计算机辅助绘制变速箱装配图的探讨

在变速箱的布局、传动方式、具体结构和元件的主要尺寸参数初步确定以后,必须绘制零件图和装配图。绘图的工作量占整个设计工作量的一半以上,因此利用计算机辅助绘图是当务之急,而其中的难点是装配图的绘制。 可利用集合求并、交、差的方法解决图形并合、裁剪、覆盖等问题。如何划分图块、如何根据上层图形的轮廓判别下层图形的可见性,消除隐蔽线是关键问题。本文以变速箱装配图为例,探讨其图块的划分,并采用引辅助线的方法对二维图形进行消隐处理,应用图论中计算结点总度的方法判定图形的轮廓线。     

A method for the blind correction of the effects of attenuation and shading in light micrographs based upon moderated histogram equalization

A means of correcting for the effects of attenuation and shading in multi-dimensional, digital, light micrographs, blindly, i.e. without the need for additional control sets of image data that record these effects, is described. The method, termed trans-elemental moderated histogram equalization (TEMHE), works with all three types of image that are collected in light microscopy: bright objects viewed against a dark background, bright and dark objects set against a grey background and darker objects set against a light background. In its most simple form TEMHE requires that the features of interest are distributed widely and evenly throughout the image data. If, however, the pattern of attenuation or shading is extracted, smoothed and the result used to correct the original set of image data, then the only restriction is that when different classes of feature are present the boundaries between them are not approximately parallel to the axes of one, or more, of the dimensions to be corrected. Moreover, when it is possible to formulate a simple model of the pattern of attenuation or shading this is no longer a constraint. The method does need to analyse a large number of elements of image data (pixels, voxels, etc.) to function correctly but it will correct shading in single frames of image data providing that they are quite large and the overall signal-to-noise ratio is relatively high.     

Retrieving true images through fine grid steps for enhancing the resolution beyond the classical limits: theory and simulations

We developed the theory of, and tested by extended simulations, a novel method for retrieving true images in a grid step much finer than both the acquisition and the optical microscope limits. We believe that the method is promising in view of avoiding the limitations on the resolution improvement in direct imaging mode systems. Two basic concepts are involved: (i) random (up to 3D) relative displacements of objects with respect to the receiving matrix and (ii) the use of a reference object firmly fixed to small signal objects for avoiding the displacement measurements. The retrieved images are created by rearranging a set of true images acquired with a lower resolution equal to the matrix pixel size. We demonstrate the good quality of the retrieved images and the possibility to visualize and detect small (convolved) objects not observed into the captured images. The method provides good opportunities for effective applications of different inverse algorithms for improving the resolution requiring, as a rule, more precisely sampled images, but at arbitrary relations between the pixel size and the optical diffraction limit. We further demonstrated the application of some deconvolution procedures for extracting highly resolved images in the object and image planes in the presence of noise. The possibility to resolve small objects beyond the two classical limits is shown by means of simulations. The estimates for the method's limiting resolution, combined with proper deconvolution processing, show that resolution in the lower nano‐dimension scale (below 10 nm) could be achieved. The requirements to the implementation of the novel method are commented as well.     

基于立体匹配技术的X射线分层成像方法研究

针对安检领域中行李箱内多层物体在二维透视图像中相互重叠,导致物体之间的形状不清晰、不易辨认和存在盲区等问题,提出了一种基于立体匹配技术的分层成像方法.该方法利用双目立体视觉原理,结合双角度投影的灰度信息对投影图像由外向内进行分割,并对分割结果基于相似属性进行匹配,结合视差进行分层重建.最后利用视差原理重建出不同深度的物体,实现了对不同深度物体的识别.经实验验证,该方法有效地消除了视图中的重叠现象,提高了对物体的识别准确率.     

Recognition and matching of occluded objects

This paper presents a method for both recognising and determining the position and orientation of occluded objects. The method works by determining the extreme points of the collection of objects, and then matching these points to a database of known objects using point-pattern matching. The results of the method are insensitive to both noise and affine transformations. Computer-vision examples are given.     

采用间接测量法对平面3-RPR机构进行运动学标定的仿真

采用间接测量对平面机构进行标定时，需要引进标准测量参照物，但参照物本身仍可能存在一定的尺寸误差；另外间接测量时要不断变换标准测量参照物的位置，又会引进位置误差。为便于解决实际问题，使研究更具可操作性，将上述误差和待标定的机构结构误差一起考虑对机构进行了标定仿真，同时在仿真过程中采用矩阵重构的方法来解决测量误差扰动的问题，避免了大规模的空间寻优。仿真结果表明，可以通过让动平台走过不同的轨迹组合来实现对平面机构的标定。     

基于无线数传模块的海上移动物标位置跟踪与监测

介绍了基于无线数传模块的海上移动物标的位置跟踪与监测，重点讨论了系统的组成、工作原理及在PC机上利用VB6．0实现对远端GPS定位信息的提取与分离方法，给出了硬件电路及关键程序代码。本成果在海上运行良好，可以推广到陆上作为搜救的辅助装备。     

机器人多指手预抓取模式聚类分析

提出一种基于计算机视觉的,以及改进的模糊C均值聚类算法的机器人多指手预抓取模式分类方法.根据人手抓取分类学,将抓取手势分为13类.选取若干具有代表性的不规则形状物体,先经视觉系统采集物体图像,然后运用数字图像处理方法提取物体的姿态、大小、形状和表面粗糙度等特征,最后利用改进后的模糊C均值聚类算法对待抓取物体进行聚类分析.实验结果表明:对比人类抓取策略,该方法具有理想的预抓取模式分类效果.     

Moderated histogram equalization, an automatic means of enhancing the contrast in digital light micrographs reversibly

A means for improving the contrast in the images produced from digital light micrographs is described that requires no intervention by the experimenter: zero‐order, scaling, tonally independent, moderated histogram equalization. It is based upon histogram equalization, which often results in digital light micrographs that contain regions that appear to be saturated, negatively biased or very grainy. Here a non‐decreasing monotonic function is introduced into the process, which moderates the changes in contrast that are generated. This method is highly effective for all three of the main types of contrast found in digital light micrography: bright objects viewed against a dark background, e.g. fluorescence and dark‐ground or dark‐field image data sets; bright and dark objects sets against a grey background, e.g. image data sets collected with phase or Nomarski differential interference contrast optics; and darker objects set against a light background, e.g. views of absorbing specimens. Moreover, it is demonstrated that there is a single fixed moderating function, whose actions are independent of the number of elements of image data, which works well with all types of digital light micrographs, including multimodal or multidimensional image data sets. The use of this fixed function is very robust as the appearance of the final image is not altered discernibly when it is applied repeatedly to an image data set. Consequently, moderated histogram equalization can be applied to digital light micrographs as a push‐button solution, thereby eliminating biases that those undertaking the processing might have introduced during manual processing. Finally, moderated histogram equalization yields a mapping function and so, through the use of look‐up tables, indexes or palettes, the information present in the original data file can be preserved while an image with the improved contrast is displayed on the monitor screen.     

基于物理属性的虚拟装配过程

针对虚拟装配系统中存在仿真程度不够高的缺点,提出基于物理属性的虚拟装配过程研究。通过分析虚拟装配过程对零部件物理属性的需求,建立零部件物理属性模型,给出确定零部件各物理属性以及自由运动状态的方法,分析碰撞响应对运动状态的影响。研究虚拟装配系统中装配对象间的交互过程,使用多刚体系统动力学分析方法对零部件装配过程中的动力学以及运动学进行分析,给出装配对象的运动学与动力学方程。通过把抽象的约束关系转换为基本约束方程表达运动副约束,并把运动副约束用于装配对象的运动分析。提出基于碰撞与静力学的稳态分析方法研究零部件达到稳定状态的条件。应用实例表明上述方法有效可行。     

暗弱空间目标的高精度定位

提出了一种暗弱空间目标的高精度定位方法,以进一步提高该类空间目标的定位精度。研究了星像质心计算和星图匹配以及光电望远镜静态指向修正模型和天文定位等算法。首先,深入分析了星像质心计算和三角形匹配算法。然后,采用Tycho-2星表和基本参数修正模型,修正光电望远镜系统静态指向误差。最后,针对暗弱空间目标定位精度低,对传统天文定位方法进行了改进,提出了"暗弱空间目标高精度定位方法",实现了暗弱空间目标高精度定位。实验结果表明:提出的暗弱空间目标高精度定位方法的测量精度优于4″,基本满足光电观测系统进行暗弱空间目标测量时对精度和稳定性的要求。