圆柱体直径测量与评定中的相关问题研究

ISO/CD 14405:2001规定了圆柱体的计算尺寸和全局尺寸,其测量与评定将面临一些亟待解决的问题.基于圆柱度误差的截面测量法,分别建立了周长直径、面积直径、最小二乘尺寸、最大内接尺寸和最小外接尺寸的评定模型.介绍了用于测量圆柱体直径的柱坐标测量机的基本结构和测控系统.以径向尺寸测量机构的标定方法为基础,给出了由电感传感器和光栅传感器测得的各采样点的径向位移转换为由这些采样点到回转工作台回转轴线的径向距离的计算公式.     

基于MATLAB的直线度测量不确定度评定程序设计

形位误差测量不确定度评定由于其测量的复杂性和测量结果评定的多样性,导致在实际测量结果中形位误差测量的不确定度评定成了难题;尤其是测量点较多,测量数据难以处理,处理结果的准确性难以保证;为此,根据直线度测量不确定度的评定过程对其进行了评定程序的设计,在程序命令的提示下,输入测量值便可得到直线度误差,输入单点测量不确定度便可得到直线度测量不确定度;该程序根据测量不确定度常用的GUM法和蒙特卡罗法思想进行设计,可得到两种不同的评定结果,不受测量点的多少、测量数据的复杂程度等因素影响;通过数据验证,程序可靠准确,为直线度测量不确定度评定提供了便捷、高效的数据处理方法;通过测量数据验证,该程序准确可靠,具有一定的实际应用价值和推广意义。     

遗传算法在圆度误差评定中的应用

针对传统最小二乘圆优化算法评定圆度误差局部收敛的问题,提出基于遗传算法的圆度误差评定方法。介绍了遗传算法基本原理和运算流程,在建立最小二乘圆数学模型的基础上,推导出待优化的目标函数,并详细描述了基于遗传算法的圆度评定优化步骤。实例计算结果表明该算法能比传统优化算法收敛到更精确的解,并具有较高的稳定性,能有效地克服局部收敛的问题。     

基于极坐标测量的圆度误差评定算法

提出一种利用极坐标测量数据求解圆度误差的网格搜索算法,其原理是在最小二乘圆心周围按一定规则布置一系列的极坐标网格点,依次以各网格点为理想圆心计算所有测点的半径值,通过比较这些半径值,实现最小区域法、最小外接圆法和最大内接圆法的圆度误差精确评定。详细叙述了算法求解圆度误差的过程和步骤,给出了数学计算公式及程序流程图。试验结果表明,该算法可有效、正确地评定圆度误差。     

一类非线性系统基于最小二乘支持向量机的自适应H∞控制

提出一类非线性不确定系统基于最小二乘支持向量机的白适应H∞控制方法．该方法基于最小二乘支持向量机估计对象的未知非线性函数,并给出了最小二乘支持向量机权向量和偏移值的在线学习规则．引入H∞控制器用于减弱外部干扰及最小二乘支持向量机近似误差对输出误差的影响．利用李亚普诺夫理论证明了整个闭环系统一致最终有界稳定．仿真结果表明了该方法的有效性．     

基于移动最小二乘法的气动力数据建模方法

针对一体化飞行器高度耦合的非线性气动问题,提出了一种基于移动最小二乘法的气动力数据建模方法;首先,对影响模型精度的因素进行了分析;接着,在构建移动最小二乘模型时采用遗传算法获取最佳支撑域半径以及最佳影响因子β,提高近似精度从而达到减少样本点的目的;得到泛化能力较强的气动力模型,并与偏最小二乘方法的建模结果进行对比;实验结果表明:移动最小二乘法的建模效果优于偏最小二乘方法,预测误差较小,证明了将该方法应用于气动数据建模是可行的。     

线性最小二乘法的RSSI定位精确计算方法

基于接收信号强度指示(RSSI)定位模型,提出了一种目标节点位置的精确计算方法。将RSSI定位问题所描述的非线性优化函数转化为线性最小二乘法估计问题,将定位结果直接用代数解表示。分别提出了目标节点信号发射强度已知和未知下的非约束线性最小二乘(ULLS)定位方法。同时对非约束线性最小二乘法下的参数进一步优化,提出了约束线性最小二乘法以提高定位精度。仿真验证了该定位计算方法的有效性,测试了不同信号强度噪声对定位误差的影响。结果同时表明,约束线性最小二乘法比非约束线性最小二乘法的定位误差更小,非常接近于定位结果的克拉美罗下界值(CRLB)。     

整体最小二乘法在精同步中的应用

为了验证整体最小二乘法(TLS,Total Least Squares)比最小二乘法(LS,Least Squares)更适用于精同步,提出了基于整体最小二乘的精同步方法;该方法以PN码基于BPSK调制的同步模型为基础,在接收端得到鉴相曲线后,对鉴相曲线零值点附近的几个固定位置的数据点利用QR分解和奇异值分解的整体最小二乘法拟合出鉴相曲线,求出同步误差;最后通过在Matlab软件上的仿真,得出结论:在噪声环境下,整体最小二乘法在同步中的应用可以得到优于基于普通最小二乘法的同步法的测量精度和稳定性;特别是在信噪比较低的条件下,基于整体最小二乘的精同步测量精度提升了3倍多,同事稳定性提升5倍多。     

基于惯导/数据链的动态相对定位方法

针对卫星导航定位在复杂环境不可靠情况下如何实现无人机机间相对定位问题,提出一种基于机载惯性导航系统与机间数据链测距相结合的动态相对定位算法。该方法利用机载数据链通信测距能力与机载惯性导航系统输出的无人机速度矢量信息结合,建立机间相对定位模型,通过最小二乘法对无人机之间的相对位置进行估计,实现无人机机间的实时相对定位能力。由于通过最小二乘法解算出的相对定位结果依然存在误差,针对最小二乘法相对定位误差,提出秩亏网平差算法对无人机机群间的相对定位误差进行校正。仿真结果表明：基于最小二乘法的相对定位方法可以减缓惯性导航系统相对定位误差发散速度并且将惯导相对定位精度提高到3倍左右,通过秩亏网平差算法校正将最小二乘相对定位精度提高2倍。     

磁传感器的非线性误差修正技术

介绍了最小二乘法多项式曲线拟合的原理和方法,以及该方法在磁传感器误差修正中的应用。对磁传感器的测量数据进行处理,利用计算机的高级语言计算拟合函数的系数,设定拟合准确度,得到函数的系数,将系数转换成十六进制数,保存到仪器的微计算机中,利用汇编语言编制误差修正程序,对测量误差进行自动修正。     

Interactive computer methods for design optimization

Two interactive methods for design optimization are discussed in this paper. The first method is implemented by the computer program GDOPT and is an essentially manual search procedure based on graphical searches of the design space within user-defined planes. In contrast, the computer program ADOPT consists of the more effective nonlinear programming techniques available and the search is mostly under computer control. The user observes progress on a graphical display and is able to modify the search procedure as desired. These two interactive methods make an extensive use of computer graphics to display search results in the form of graphs, contour plots, sensitivity curves, and search trajectories. The designer interacts with the programs through these displays and is an active participant in the decision making process. It is believed that this integrated approach to design optimization can result in an enhanced understanding of the design problem and an effective convergence to the optimum design. An example is presented which illustrates the effectiveness of this interactive technique.     

Interactive graphical program portability

In the opinion of the authors, a fully portable interactive graphical program should be able to take advantage of the object display terminal's hardware features where these are beneficial to the efficiency of man-machine interaction. By analysing the FORTRAN code of an interactive graphical program designed to operate on both refresh displays and storage tubes, a program design approach has evolved which attempts to reduce the effort required to achieve this aim.     

Effects of Integrated Graphical Displays on Situation Awareness in Anaesthesiology

Anaesthetic information displays have been shown to influence anaesthesiologists’ situation awareness. In study 1 an object display was compared with the traditional display currently used. Twelve anaesthesiologists (residents and faculty members) participated in a simulator evaluation of the displays. Reaction times for detection of critical events and situation awareness were measured. The object display improved situation awareness for one of four test scenarios. Low-level situation awareness was higher with the traditional display, and medium-level situation awareness was higher with the new display. In study 2, an integrated 3D display was compared to the traditional display. Twelve students participated in the evaluation. The new 3D display helped the observers to see changes more rapidly. In one scenario, situation awareness was higher with the new display than with the traditional display. In summary, during 63% of the simulated scenarios, reliable differences were found in favour of the new displays. Thus, by introducing integrated graphical displays in the operating room, anaesthesiologists’ performance may be improved.     

Graphical displays of human strength data

To facilitate the effective use of strength data in a human-task simulation environment, we have developed graphical methods to display the multidimensional characteristics of strength data. We use human figures together with two and three dimensional graphical symbols, colours and animations to visualize the effects of different parameters on strength. These displays give a dynamic view of the effects of various parameters on strength, and illustrate safe and forbidden body postures (or regions) in terms of strength capabilities.     

Under the weather: an evaluation of different modes of presenting meteorological information for pilots

Understanding current and forecast weather conditions for a planned route of flight is vital for general aviation (GA) pilots. Weather information can be obtained from multiple sources and in multiple formats, ranging from abbreviated code provided by aviation weather forecasters to animated graphical displays available on TV and the Internet. The present study investigated the effectiveness of graphical displays of meteorological information. A commercially available graphical display was ergonomically redesigned and the original and redesigned displays were compared with an ordinary text statement. Recall of information was significantly affected by display type. Comparisons showed the ergonomically redesigned display to be superior to the ordinary text statement. Performance was affected by participants’ general level of familiarity with evaluating data displays as measured by their area of study (sciences or humanities). The generalizability of the results to the pilot population is discussed.     

Configural display design techniques considered at multiple levels of evaluation

Two studies were conducted to examine issues in the design and evaluation of configural displays. Four design techniques (bar graphs/extenders, scale markers/ scale grids, color coding/color layering/color separation, and annotation with digital values) were applied, alone and in combination, to a baseline configural display, forming 10 displays. Two qualitatively different evaluations assessed performance for (A) low-level data probes (quantitative estimates of individual variables) and (B) system control and fault detection tasks. Three of the four design techniques improved performance significantly for low-level data probes (color coding was the exception). A display with digital values only (i.e., no analog configural display) produced the poorest performance for control/fault detection tasks. When both levels of evaluation are considered, a composite display (configural display with all four techniques applied) was clearly the most effective. Overall, the findings obtained in the two experiments provide very limited evidence for the generalization of results between evaluations. The two levels of evaluation, the display manipulations, and the patterns of results are considered in terms of a cognitive systems engineering evaluation framework. General implications for the evaluation of displays and interfaces are discussed. Actual or potential applications include design techniques to improve graphical displays and methodological insights to focus and improve evaluation efforts.     

DMS-Dynamic motion simulator

DMS is a graphics program that displays the output of multibody systems programs like DYNACOMBS¹. The menu driven program supports a full range of display options to aid the user in the visualization of his or her output. A small CORE compatible graphics package is included to produce graphical output on Tektronic 4010 terminals or emulators.     

Decomposition of three-dimensional objects into spheres

Algorithms are presented for converting between different three-dimensional object representations: from a collection of cross section outlines to surface points, and from surface points to a collection of overlapping spheres. The algorithms effect a conversion from surface representations (outlines or surface points) to a volume representation (spheres). The spherical representation can be useful for graphical display, and perhaps as an intermediate representation for conversions to representations with other primitives. The spherical decomposition also permits the computation of points on the symmetric surface of an object, the three-dimensional analog of Blum's symmetric axis. The algorithms work in real coordinates rather than in a discrete space, and so avoid error introduced by the quantization of the space.     

Computer graphics as a memory aid and a thinking ald

Abstract The increasing use of microcomputers in classrooms opens up new possibilities for using visual, diagrammatic methods of teaching. This article sets out to explain why we sometimes abandon words and turn to graphical methods of communication. It is argued that a well designed graphical display can function as a kind of memory store. This view of the graphical display as a memory aid and a thinking aid suggests three principles for the program designer: parsimony, accessibility and reflection. 'Progressive graphics', where a display changes in step with the users' thinking, seem particularly suited to implementation on a computer.