提出将粒子群优化算法与拟随机序列法相结合对基于CAD模型引导测量的自由曲面进行高精度检测和轮廓度误差评定的方法.为解决用三坐标测量仪检测自由曲面时存在的设计坐标系与测量坐标系不重合问题,提出用拟粒子群优化算法来实现被测曲面与设计曲面精确定位；针对自由曲面特点,采用轮廓峰谷误差和轮廓均方根误差综合评定自由曲面的形状误差.最后,阐述了用拟粒子群优化算法实现曲面匹配时目标函数值的计算方法,确立了用拟粒子群优化算法优化求解参数向量的具体步骤.对仿真实例和大量实测零件自由曲面轮廓度误差的计算表明:采用本文方法能够实现自由曲面精确定位,其轮廓度误差评定精度比由三坐标测量仪内置软件计算的结果高8％～15％,适用于对高精度自由曲面零件形状误差的评定.%An evaluating method by combination of particle swarm optimization and quasi-random sequence was proposed to detect precisely and evaluate the profile errors of freeform surfaces inspected by Computer Aided Design (CAD) model-directed measuring. In order to solve the un-repetitive problem between design coordinate system and measurement coordinate system when a Coordinate Measurement Machine (CMM) was used to inspect free form surfaces, Quasi Particle Swarm Optimization (QPSO)was proposed to realize the precise localization between measured surface and design surface. Then, according to the features of freeform surface form, the peak-valley error and root mean square error were used to evaluate the freeform surface forms together. The computation method of the objective function was described, in which QPSO is used to match the measured surface and the design surface and the detailed steps were established for solving parameter vectors by using QPSO. Finally, by calculating the surface profile errors of simulation example and many practical measured parts, the results verify that the proposed method can locate precisely freeform surfaces and the evaluation precision of freeform surface profile errors by the proposed method is higher 8%-15% than that by CMM software. The method is suitable for the form error evaluation of high precise freeform surface parts.
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