共查询到20条相似文献,搜索用时 687 毫秒
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提出了一种基于插值拟合的在线复杂刀具轨迹平滑压缩算法,该算法依据主导点的选取策略,对原始数据点进行离线预处理,然后进行主导点的在线插值拟合以及非主导点的误差检测,进而生成一条满足拟合精度要求的B样条曲线。主导点依据离散数据点的曲率阈值、曲率极大值、曲线拐点,以及分段Bezier曲线逼近拟合后的误差最大值点进行选取。在具有C2连续性的分段Bezier曲线逼近拟合前,需要利用长度均分策略,提取长度突变点作为新增的主导点,以保证拟合的准确性。对主导点进行B样条插值拟合后,利用轮廓误差跟随法对非主导点到拟合曲线的误差进行检测。该方法与牛顿迭代法相比,其计算速度更快且能提高算法效率。仿真结果表明,提出的算法可对复杂刀具轨迹进行平滑压缩,且误差检测的精度能够满足要求。 相似文献
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为了解决涡轮叶片曲面不光顺而造成的数控加工刀轨生成失败的问题,本文针对叶片曲面截面线进行光顺拟合,提出了一种三次非均匀B样条曲线整体光顺逼近算法。该算法建立了一个由最小二乘法、型值点曲率和、型值点曲率变化和三项组成的目标函数,并利用高斯消元法求出最优控制顶点坐标序列。该算法可以使曲线在给定的逼近误差范围内,实现型值点曲率和降低的同时,曲率变化也更加均匀。最后将算法程序嵌入UG5.0二次开发程序中实现自动光顺拟合模块的开发,并通过与已存在的算法进行光顺效果对比实验,验证了本文算法更有效。 相似文献
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综合比较多种非圆曲线逼近拟合方法,等误差曲率圆法是最佳方法.文中对等误差曲率圆法进行了数学描述,提出了可行的拟合算法,并基于该算法编制出程序流程图.利用该程序流程图,为数控编程人员编制非圆曲线程序提供了思路,具有一定应用价值. 相似文献
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等误差面积法三点圆圆弧段逼近非圆曲线 总被引:1,自引:1,他引:0
详细介绍等误差面积法圆弧段逼近非圆曲线节点的计算方法 ,并通过编程误差的分析 ,建立逼近误差面积相等的三点圆圆弧段逼近非圆曲线节点坐标计算的算法 相似文献
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基于NURBS曲线拟合的刀具路径优化方法 总被引:1,自引:0,他引:1
为解决复杂曲面高速、高精度加工中由于微小直线段链逼近自由曲线产生的刀具路径不连续问题,提出一种基于非均匀有理B样条曲线拟合的刀具路径优化方法.在该方法中,通过分析刀具路径的几何特征鉴别需要平滑的连续直线段链,对其分段进行基于最小二乘法的非均匀有理B样条曲线拟合优化,并设置相邻段连接点处的边界平滑条件,还原刀具路径应有的连续性.拟合算法采用特征点搜索法设定曲线参数,通过误差控制的曲线节点向量和控制顶点调整保证拟合曲线精度.实验表明,经过该算法拟合优化后的刀具路径具有良好的平滑性,显著提高了曲面加工的精度和效率. 相似文献
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为提高利用形状信息优化点云逼近曲线的准确性,提出了一种基于曲率及误差分布的点云逼近曲线优化算法.该算法首先快速地创建满足误差限的非最优样条曲线,据此获得较为准确的曲率分布作为形状信息;然后,以大于所给曲率阈值的角点作为种子点,构建出点云的三次序号参变量样条逼近曲线.当逼近曲线误差不满足误差限时,以误差的分布情形确定型值点的添加位置.使得每一次型值点添加后最大误差均减小.通过数条点云曲线实验表明,该算法显著地减少了逼近曲线的控制点数目. 相似文献
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Huang Xiaoping Xiong YoulunSchool of Mechanical Science Engineering Huazhong University of Science Technology Wuhan China 《机械工程学报(英文版)》2002,15(2):121-125
The profile error evaluation of complex curves and surfaces expressed in parametric form is considered. The linear error model is established on the base of two hypotheses firstly. Then the profile error evaluation is converted into one of these optimal formulations: MINIMAX, MAXMIN and MINIDEX problems, which are easier to be solved than the initial form. To each one of them, geometric condition and algebraic condition are presented to arbitrate whether the ideal element reaches to the optimal position. Exchange algorithm is proven highly effective in searching for solutions to these optimization problems. At last some key problems in tolerance evaluation of freeform surfaces and curves in B spline method are discussed. 相似文献
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李贵红 《机电产品开发与创新》2011,24(5):178-179
对于数控加工中参数曲线的加工,提出了一种新的插补算法,该算法利用泰勒展开对曲线方程进行重构,引入误差补偿思想,对插补过程中产生的误差反复补偿,从而满足目标要求,通过仿真和实际切削实验,表明该算法简单实用、通用性强、算法精度高,能够保证参数曲线的光滑性,有利于提高参数曲线加工质量和加工效率. 相似文献
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《Measurement》2014
For aspheric surface measurement with wavefront sensing technology, after obtaining the slope or curvature as the measurement raw data, the data processing algorithm must be re-studied for high performance in practical application. This paper designs, analyzes and compares five different algorithms to generate wavefront for aspheric surface measurements, especially for practical measurements with noises and missing data. Simulation and experimental results show that in ideal condition without any noise in the system, direct fitting yields perfect results without error; the algorithms including Southwell reconstruction achieve better results under practical conditions, where there exist real issues such as noise and abnormal data. Reconstruction is therefore an essential step as it significantly improves the measurement stability and reliability, and enables the system feasible for practical applications. Furthermore, Southwell algorithm is extended for applications with missing data, which is most likely happen when the surfaces to be measured possess large dynamic range. 相似文献
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针对三轴磁力仪在磁场测量过程中的磁干扰问题,提出了基于阻尼粒子群优化算法的磁测误差补偿方法。建立了磁力仪误差和载体磁干扰的一体化误差补偿模型,分别采用阻尼粒子群算法和Two-step方法对非线性观测模型进行参数估计。以质子磁力仪数据作为真值,借助无磁转台充分连续采样,实验结果显示,阻尼粒子群算法对于磁场测量误差具有良好的抑制作用。补偿后,由阻尼粒子群算法和Two-step方法得到的均方根误差分别由1 025.7降至60.304 4、581 n T。结果表明,阻尼粒子群算法取得了更好的补偿效果,补偿精度提高了至少一个数量级,为磁场测量误差提供了一种非常有效的补偿方法。 相似文献
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Jinho Park Sungho Nam Minyang Yang 《The International Journal of Advanced Manufacturing Technology》2005,26(4):359-365
This paper deals with the real-time NURBS interpolation method in which the interpolation error between the ideal curve and the interpolated curve is compensated within the machine basic length unit (BLU). Parametric curve interpolation methods are based on the Taylor series expansion of curve parameters and an approximation. This approach enables effective feed command generation following the target curve. However, the interpolation error caused by the curve segmentation cannot be controlled.In this research, a two-stage interpolation method that compensates for interpolation errors within machine BLU is proposed. The interpolation result was filtered by an acceleration/jerk limitation equation. Through this two-stage interpolation, both the interpolation error condition and the motion dynamics can be satisfied.Using computer simulations in which interpolation results are revaluated by a numerical iteration method, it is shown that the two-stage interpolation algorithm can interpolate target curves precisely with geometric and dynamic contentment. The proposed algorithm was implemented in the CNC simulator system and an experimental run was conducted to identify the real-time adaptation. 相似文献
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双曲柄连续轨迹生成机构的优化综合 总被引:1,自引:1,他引:0
本文首先提出从动杆杆长结构误差的概念,然后基于该结构误差建立优化综合模型,采用改进遗传算法获取综合结果。从前杆杆长结构误差不仅计算便利,且能有效反映出实际生成的轨迹曲线与预期的理想轨迹曲线间的差异,避免了在两轨迹曲线上选择对应比较点的困难。改进遗传算法保证了获得全局最优解。综合实例结果表明了本方法的有效性。 相似文献
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热电偶群炉自动检定系统用于自动检定各种工作用热电偶,能满足短时间内检定大批量热电偶的要求,该控温系统采用RS485总线智能仪表和SSR进行控温,先进的专家PID算法,有效地防止控温过程中的超调和欠调现象,实现自然、平稳的温度过渡,既可减少不必要的等待时间,又可得到理想的恒温指标. 相似文献
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In practice, it is necessary to understand the general quality status of a batch of circular features machined under the same or similar conditions. In particular, it is necessary to understand the possible worst case among such a batch of circular features. To this end, a brand-new concept called “batch circular form error” is presented in this paper. Detailed definitions of batch circular form error including batch circular form error with ideal conditions and batch circular form error with realistic conditions are provided. Accordingly, the evaluation algorithms of batch circular form error are developed. The algorithms include the characterization of the deterministic profile of circular features and the evaluation of batch circular form error based on a given profile confidence level. Case studies with simulation and experimental data are used for demonstration. The results show that the batch circular form error can be estimated with the data measured from any circular feature in the batch, as long as the sample size is large enough and random ratio is not too large. 相似文献
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Mohammad Reza Chalak Qazani Siamak Pedrammehr Mohammad Javad Nategh 《The International Journal of Advanced Manufacturing Technology》2014,75(9-12):1763-1771
Accuracy is greatly affected by nonlinear motion of hexapods. This need is more obvious when these mechanisms are used in machining environments where precision and surface qualities are of critical importance. In this paper, comprehensive algorithm for hexapod tool path programming is developed. Using C#.Net, this algorithm is developed based on circular motion and rotation of the table which has the capability of checking nonlinear error and keeping it in a controlled limit as well. Improved Tustin algorithm is used for interpolating circular path. To evaluate the accuracy of the developed algorithm on a freeform surface, a turbine blade is scanned, and its CAD model is developed. Taking zigzag strategies, movement on turbine blade surface is approximated with smaller circles using the algorithm presented in this paper. The output accuracy resulted from interpolation algorithm for passing on turbine blade surface is studied in SimMechanics of MATLAB software. Using Total Station camera, motion path of two turbine blades with different radius curves on the hexapod table is experimentally obtained. Finally, it can be stated that the developed algorithm based on circular interpolation has the capabilities of motion on freeform curves. 相似文献