Analytical estimation of error in flank milling of ruled surfaces

This article introduces a method to estimate geometric error during flank milling of a ruled surface. The various positioning schemes developed by researchers are intended to reduce this geometric error in order to mill with larger sized milling cutters while respecting the tolerance interval. There are two trends in positioning: either positioning is simple and right from the start it is easy to determine design of the maximum allowed milling cutter radius, or positioning is complex and determination of the maximum milling cutter dimensions can only be conducted after digital calculations of the error. It will then be necessary to choose another milling cutter radius and recommence the positioning procedure and error calculation in order to validate the tool. In the present study, a method to estimate error in the scope of complex positioning is presented. The aim is to be capable of choosing a maximum cutting tool radius that respects the tolerance interval.     

排爆机器人机械臂定位精度误差自动补偿方法研究

针对于排爆机器人在进行排除爆破物质时,机械臂不能满足绝对准确的定位要求,位置检测精度与实际距离之间存在一定的误差。为了解决这一问题,提出排爆机器人机械臂定位精度误差自动补偿方法。基于D-H运动模型和微分变换法创建排爆机器人机械臂位姿误差模型,对误差模型进行重复参数分析,去除重复参数获得可辨识的线性方程;在可辨识的运动学参数误差模型线性方程中加入一个增量进行误差补偿。最后通过仿真实验结果表明,所提方法通过对机械臂位姿误差模型进行有效补偿,使排爆机器人机械臂绝对定位精度均值提升1.3mm。     

Prediction of geometric errors of robot manipulators with Particle Swarm Optimisation method

This paper reports on the prediction of the expected positioning errors of robot manipulators due to the errors in their geometric parameters. A Swarm Intelligence (SI) based algorithm, which is known as Particle Swarm Optimization (PSO), has been used to generate error estimation functions. The experimental system used is a Motoman SK120 manipulator. The error estimation functions are based on the robot position data provided by a high precision laser measurement system. The functions have been verified for three test trajectories, which contain various configurations of the manipulator. The experimental results demonstrate that the positioning errors of robot manipulators can be effectively predicted using some constant coefficient polynomials whose coefficients are determined by employing the PSO algorithm. It must be emphasized that once the estimation functions are obtained, there may be no need of any further experimental data in order to determine the expected positioning errors for a subsequent use in the error correction process.     

一种空间测向定位的解析算法和误差仿真分析

对于测向交叉定位系统,就空间模型的情况,给出了一种直接求解方法。还讨论了定位误差与观测误差,布站误差之间的关系,并仿真得出了不同测向精度条件下的误差GDOP分布图,得出的结果对实际应用有指导意义。     

热超声倒装键合机的视觉系统定位精度实验研究

简要说明了视觉定位原理及定位实验数据的采集过程,并对倒装键合实验台的视觉定位系统的误差进行了理论分析。以热超声倒装键合实验台为平台,应用HexSight图像处理软件,对实验用1mm×1mm的表面有8个凸点的芯片进行定位实验。根据测得的实验结果,分别对定位系统的平移误差和旋转误差进行了分析。采用对5次识别结果取平均值的优化方法,使角度误差减小到0.023766°,单项误差减小到0.183μm,综合误差减小到0.554μm。试验结果表明,该视觉定位系统达到了热超声倒装键合过程中芯片与基板之间的定位精度的要求。     

Positioning error guarantee method with two-stage compensation strategy for aircraft flexible assembly tooling

Flexible assembly tooling is an important manufacturing equipment for aircraft products, the positioning error of its end locating effectors determines the final assembly precision directly. To realize its accurate positioning, a precise and effective error compensation method based on two-stage strategy, is proposed. Based on the structure and working conditions of locating unit, an assembly measuring field is set up, for acquiring the actual geometric error status and the various time-varying assembly parameters in practical assembly site. Considering the transfer and accumulation of actual geometric error and deformation error, the positioning error mechanism model at the pre-compensation stage is proposed. Then with the actual assembly conditions and the measured training/testing data set of the positioning error, the SLFN motion prediction model for the locating unit is proposed, aiming at clarifying the nonlinear and strong coupling relationship between the input motion value and the output positioning error. And the SLFN data model has a good fitting and prediction ability. Combining the advantages of error mechanism modeling and measurement data modeling, a semi-mechanism model is proposed at the accurate compensation stage. Where the positioning error is predicted with SLFN model for a given input motion value, acting as an error generator. Experiment results showed that the final measured average error is 0.036 mm, having an enhancement ratio of 25.77 % contrasting with the error mechanism model. This accurate modification and compensation solution makes the relationship between causal factors and output positioning error more comprehensive, and the overall effect is more consistent with the practical situation, i.e. a higher precision value and an accurate input/output relationship can be gained.     

多颜色模型下的乒乓球快速检测与实时跟踪研究

乒乓球机器人视觉系统中的乒乓球检测主要有基于运动分析和基于单一颜色模型分割两种方法.基于运动分析的方法对运动背景干扰的鲁棒性较差,而基于单一颜色模型的分割方法会受到相近颜色及光照变化的干扰.为此,提出了多颜色模型下的乒乓球分割算法,结合RGB与HSV两种颜色模型的颜色表达特性提取出乒乓球区域,并利用质心法对乒乓球进行中心定位.在此基础上,提出基于前帧位置的感兴趣区域算法,对乒乓球进行实时跟踪.实验表明,该方法能够在复杂环境下对乒乓球进行快速精确定位,算法处理时间小于10 ms,定位误差小于20 mm,满足乒乓球机器人的击球需要.     

轻小型无人机遥感定位系统误差消除技术研究

传统无人机定位系统误差消除技术存在误差消除精准度低的问题,需对轻小型无人机遥感定位系统误差消除技术进行深入研究。根据轻小型无人机航线、地理参考和初始位置坐标系,构建轻小型无人机遥感定位模型;利用该模型对目标定位原理展开分析,通过模型构建和无人机隐秘飞行特征,对目标位置进行转换,获取转换后的坐标系位置信息,通过无人机飞行姿势变化幅度范围,获取精准误差影像序号,并进行修正,由此完成系统误差消除。实验结果证明,该技术误差消除精准度较高。     

基于RSSI测距的传感器网络定位算法研究

基于RSSI(Received Signal Strength Indicator)的测距技术根据理论或经验信号传播模型将传播损耗转化为距离.在实际应用环境中,由于多径、绕射、障碍物等因素,无线电传播路径损耗使得定位过程中产生距离误差.通过对二维空间定位过程中产生距离误差区域进行分析,提出了基于RSSI的新的定位算法ERSS.该算法计算简单,定位过程中节点间不增加通信开销,无需硬件扩展.仿真实验表明,该算法较普通的基于RSSI的测距方法有了明显的改进,提高了距离估计的精度,适合在通信开销小、硬件要求低的传感器网络节点上应用.     

A geometry-based error estimation for cross-ratios

For choosing specific cross-ratios as 2D projective coordinates in various computer vision applications, a reasonable error analysis model is usually required. This investigation adopts the assumption of normal distribution for positioning errors of point features in an image to formulate the error variances of cross-ratios. Based on a geometry-based error analysis, a straightforward way of identifying the cross-ratios with minimum error variances is proposed. Simulation results show that the proposed approach, as well as a further simplified alternative, yield much better estimations of minimum error variances in terms of accuracy, cost, and stability compared with some other methods, e.g., the one based on the rule given by Georis et al. (IEEE Trans. Pattern Anal. Mach. Intell. 20 (4) (1998) 366). Some causes of the performance differences in the estimations are explained using a special configuration of point features.     

射频仿真系统目标精度改进校准方法

这篇文章提出了一种改进的射频仿真系统低频段（1—2GHz）精度校准方案。方案是在对大量实验数据分析的基础上提出来的。实验数据证明仿真系统目标位置精度误差满足可重复性,目标阵列是一个稳定的“准”时不变系统。综合系统中“场”和“路”的误差影响,建立目标精度误差修正算法,得出对应于目标位置误差的信号辐射功率偏差并在系统中加以补偿,将目标“硬拉”回来,提高射频仿真系统低频段的精度指标。方法可以应用于国内众多的射频仿真系统,实现高精度的射频目标仿真。     

多目标规划模型在航迹规划中的应用

智能飞行器是由动力装置驱动,并在计算机系统自动引导进行的。航迹规划是实现飞行器智能导航并成功完成任务的技术保障。本文针对智能飞行器飞行过程中受到飞行器的最小转弯角限制以及定位误差的影响,提出了基于A*算法的多目标规划的数据模型以及寻求最优航迹规划路径的算法,并用两个校正点数据集进行了验证。结果显示,改进后的A*算法可以快速地规划出满足限制条件的最优路径。     

涡轮流量传感器在闭式水泵试验台中的测量误差分析

对闭式水泵试验台水泵流量测试的误差来源进行了分析，并针对各项来源误差提出了减小措施，对泵生产企业和检验单位提高测试精度具有一定的启迪。     

仿真转台误差分析及误差建模

该文针对某型三轴仿真转台的结构和工作原理，探讨了影响系统空间误差的各个误差源，总结出三轴转台的全部几何运动误差。基于多体系统运动学的基本原理，阐述了系统的拓扑结构，分析了多体系统有误差运动的基本规律，推导出特征矩阵构建方法，研究了根据特征矩阵得到三轴转台的综合空间误差。此空间误差包括了系统的空间指向误差和空间位置误差，为转台的误差补偿和精度分配提供了理论依据。该方法也可为其他类型的多自由度运动系统的误差建模及误差补偿提供理论参考。     

Dynamic reliability of thermally deduced positioning precision of ball screw systems based on random moving difference method

The positioning precision of a half-closed-loop feed system of machine tools is usually affected by the frictional heat of the system. The axial thermal errors of the working table exceeding the axial allowed tolerance is a type of failure mode of the ball screw system in positioning precision. At present, thermal error prediction and compensation methods have poor accuracy retention because they do not consider the randomness of the parameters. In order to solve the problem, we present a new random moving difference method of studying a tree-like heat transfer with thermally excited moving branches. Furthermore, based on the random moving difference method, a dynamic reliability prediction model (DRPM) of thermally deduced positioning precision is proposed, which was used in the study for predicting the dynamic variation performance of the heat boundaries in the ball screw feed drive system and the dynamic reliability of positioning precision of the system. Finally, the prediction performance of the presented method is verified under a CNC lathe. Our method provides the theoretical and practical foundation for a real-time monitoring positioning precision reliability index while describing the positioning precision accurately because it effectively takes into account the random parameters.     

基于路径表的室内地图匹配方法

地图匹配算法能有效地提升定位精度,是定位技术不可或缺的一部分。为提高路径匹配正确率,并适应室内定位环境,提出一种基于路径表的室内地图匹配方法,在传统地图匹配方法的基础上建立一个路径表存放候选路径的信息,每次路径匹配时,都从表中选取具有最优权重值的路径进行匹配。在匹配过程中多处设置查错和纠错机制,即使在出现匹配错误的情况下,也能及时从路径表中重新选取正确路径。较强的查错和纠错功能使其特别适合用于室内复杂环境下的地图匹配。实验结果表明,与传统的地图匹配方法比较,能有效地提升匹配精确度。     

无相位截断误差DDS的设计与FPGA实现

通过修改传统的直接数字频率合成（DDS）设计方法,提出了一种基于查找表的无相位截断误差的DDS设计方案并用FPGA平台予以实现。该方案不做相位截断,并利用幅度量化的数学特性建立查找表,在查找表深度可容忍的前提下大幅降低了杂散噪声,减轻了存储量对提高信号精度的限制,消除了传统设计中相位截断给最终输出信号频谱的影响,提高了DDS的性能。     

捷联式惯导系统误差解析解研究

该文在一定的假设条件下利用捷联惯导系统的三维误差状态模型求解出了单通道误差状态方程的解析解,列表给出了各误差源对于某一特定误差状态的动态影响.然后利用某型导弹的弹道数据通过对两种误差模型在同一条件下进行仿真的方法验证了单通道误差状态方程解析解的正确性.单通道误差模型对分析各种误差源对系统的影响,确定在满足系统精度要求的条件下主要误差源的选择范围,进行系统精度分配提供了十分方便直观的方法.     

Development of a monocular vision system for robotic drilling

Robotic drilling for aerospace structures demands a high positioning accuracy of the robot, which is usually achieved through error measurement and compensation. In this paper, we report the development of a practical monocular vision system for measurement of the relative error between the drill tool center point （TCP） and the reference hole. First, the principle of relative error measurement with the vision system is explained, followed by a detailed discussion on the hardware components, software components, and system integration. The elliptical contour extraction algorithm is presented for accurate and robust reference hole detection. System calibration is of key importance to the measurement accuracy of a vision system. A new method is proposed for the simultaneous calibration of camera internal parameters and hand-eye relationship with a dedicated calibration board. Extensive measurement experiments have been performed on a robotic drilling system. Experimental results show that the measurement accuracy of the developed vision system is higher than 0.15 mm, which meets the requirement of robotic drilling for aircraft structures.     

GIS中衡量位置数据不确定性的可视化度量指标族探讨

点是矢量GIS中最基本的元素，线和面可以由其本身的特征点来加以抽象和表达。针对当前国际GIS数据质量标准中，只定义了衡量点位数值精度的情况，应GIS可视化的要求，从图形角度出发，借鉴测绘学科中衡量平面点元位置不确定性的几何误差椭圆方法，通过计算点位坐标落入其本身误差椭圆内的概率大小，来定义矢量GIS中衡量点、线和面位置数据不确定性的点位误差椭圆、线位误差和面位误差和可视化度最指标装，以期丰富和完善当前GIS数据质量的指标体系，从而可以更好地控制各种矢量GIS数据库中的精度。