共查询到19条相似文献,搜索用时 109 毫秒
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分析了B样条曲线的光顺拟合方法和均匀B样条曲线的升阶方法,针对截面线上数据点个数变化较大的情况,提出了曲面光顺拟合的方法,并给出了计算实例。 相似文献
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以螺杆钻具廓形曲线为研究对象,通过遗传算法对其进行光顺处理。利用三次B样条曲线拟合算法进行数值分析,得到螺杆钻具廓形曲线;通过对B样条曲线的降次处理得到拟合曲线的曲率;检测待光顺的型值点,以样条曲线型值点的变化量作为优化变量,通过制定遗传策略,加快算法收敛速度,完成光顺算法。经过验证:该算法准确有效并符合约束条件。 相似文献
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列表点曲线数控加工方法的分析与研究 总被引:4,自引:0,他引:4
分析和研究了列表点曲线的数控加工问题,提出了先以三次参数样条进行插值,再用双圆弧拟合的方法。实例证明:该方法拟合后的曲线光顺,偏差较小,并且算法简单。 相似文献
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测量数据的B样条曲线逼近算法 总被引:1,自引:0,他引:1
本文根据遗传算法,提出了一种B样条曲线逼近大量测量点的方法。为了使曲线具有良好的光顺性和曲线在端点处较好的控制性,本文采用端点插值的三次非均匀B样条算法逼近测量数据点。 相似文献
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ZHU Weidong KE Yinglin College of Mechanical Energy Engineering Zhejiang University Hangzhou China 《机械工程学报(英文版)》2007,20(4):112-116
A method to reconstruct symmetric B-spline curves and surfaces is presented.The symme- try property is realized by using symmetric knot vector and symmetric control points.Firstly,data points are divided into two parts based on the symmetry axis or symmetry plane extracted from data points.Then the divided data points are pararaeterized and a symmetric knot vector is selected in order to get symmetric B-spline basis functions.Constraint equations regarding the control points are deduced to keep the control points of the B-spline curve or surface to be symmetric with respect to the extracted symmetry axis or symmetry plane.Lastly,the constrained least squares fitting problem is solved with the Lagrange multiplier method.Two examples from industry are given to show that the proposed method is efficient,robust and able to meet the general engineering requirements. 相似文献
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关于B样条曲面造型及其刀位数据计算的探讨 总被引:1,自引:0,他引:1
复杂形状零件的几何建模是数控编程的首要环节,选择合适的曲面造型方法有利于刀位计算和数控加工编程;本文采用三次B样条曲线为基础的双三次B样条曲面造型方法,并给出了其矩阵表达式,在此基础上能十分方便地进行点矢和法矢计算;针对该造型方法,还给出了三轴数控加工中的刀位数据计算方法。 相似文献
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点云数据曲面重构和小波分解研究 总被引:3,自引:0,他引:3
根据三坐标测量机测得的点云数据,提出了一种准均匀B样条曲面重构和小波分解方法。该方法通过对测量数据的分层、排序,自动建立了数据点的拓扑信息。为了生成矩形域网格,构造插值于扫描线上数据点的非均匀B样条曲线,再对其均匀采样,以保证曲面插值精度。对反算出的控制点网格进行小波分解后得到了多级逼近曲面。采用面向对象的编程技术,开发了相应的模块。利用写引擎把构造和分解的曲面保存为IGES文件,并直接导入商用3维CAD软件中进行后续处理。该方法具有较好的工程应用价值。 相似文献
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用遗传算法拟合传感器的输出特性 总被引:8,自引:1,他引:8
本文提出了一种用遗传算法拟合传感器输出特性的新方法。结果表明采用这种方法,不仅能拟合Gauss-Newton等传统非线性最小二乘法难以处理的传感器输出特性,而且能得到较高的精度。 相似文献
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《Measurement》2014
The moving least squares (MLS) method and the moving total least squares (MTLS) method have been developed to deal with the measured data contaminated with random error. The local approximants of MLS method only take into account the error of dependent variable, whereas MTLS method considers the errors of all the variables, which determines the local approximants in the sense of the total least squares. MTLS method is more reasonable than MLS method for dealing with errors-in-variables (EIV) model. But because of the weight function with compact support, it is complicated to choose fitting method for the best performance. This paper presents an Adaptive Moving Total Least Squares (AMTLS) method for EIV model. In AMTLS method, a parameter λ associated with the direction of local approximants is introduced. MLS method and MTLS method can be considered as special cases of AMTLS method. Curve fitting examples are given to prove the better performance of AMTLS method than MLS method and MTLS method. 相似文献
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正确的人体点云数据分析不仅是人体3D测量的必要手段,更是未来服装数字化设计的基础,也是服装定制化智能生产的数据来源。人体散乱点云数据相比规整数据拥有更多的噪声及不规则性,这使得提取轮廓以及提取分割特征点更加困难。为了解决人体散乱点云数据分割难题,提出了基于移动最小二乘的切割算法。首先使用主成分分析法进行点云数据的调整,并使用夹角分析法提取投影到特定平面的二维轮廓。在此基础上,采用移动最小二乘法对部分二维数据点进行局部拟合并根据导数信息提取分割特征点。最后,利用VT K作为点云显示平台,对不同人体点云数据进行算法验证。实验结果表明,该分割方法实用可靠。 相似文献
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Lixin Cao Jian Liu 《The International Journal of Advanced Manufacturing Technology》2008,35(11-12):1053-1064
For given data points on different cylindrical section curves of marine propeller during the design period, the fair fitting method with the least squares of the cubic B-spline curve has been used to form cylindrical section curves with different radius. Then the control points of the cylindrical section curves were used as new data points to process fair fitting in another direction, and the pressure surface and the suction surface of the propeller can be acquired at last. Aims to overcome disadvantages of the present machining method of propeller, such as lower machining precision and efficiency, repeated clamping, and limited machining scope, a new machining method—the second order osculating machining method—has been presented. By using this method, not only the cylindrical cutter and the machined surface can keep line contact, but also the propeller can be machined with one clamping. It’s very suitable for the machining of propeller with larger projected area ratio and the machining precision and efficiency will be improved. 相似文献