螺纹参数测量中工件定位误差分析和补偿

利用齐次坐标变换方法从理论上研究了单针扫描式螺纹测量仪的工件定位误差模型，并考虑探针尖头的几何形状，建立了更加精准的曲线方程。以该曲线作为最小二乘拟合曲线，根据数学模型的特点和参数的取值范围，采用改进的单纯形-模拟退火(SMSA)算法，通过对标准件的测量，求解模型参数，补偿对应误差，减小了简单直线拟合的模型误差。基于该方法，在自主研发的测针式螺纹测量仪上进行了实验验证，结果表明，所述模型更符合实际情况，能够有效地减小工件定位误差。

Analysis and Compensation of Positioning Errors of Workpiece in Thread Measurement

The  positioning errors of workpiece on thread measuring instrument were investigated and analyzed by the homogeneous coordinate transformation method. A precise mathematical model of workpiece was established including the geometry of the probe. The measuring curve was fitted using least square fitting method. The model errors caused by simple fitting line were decreased. According to the features of mathematical model and the range of the parameters, an improved simplex-simulated annealing algorithm was applied to calculate the model errors. Validation experiments and measurement were made based on the thread measuring instrument which was developed independently. The measuring results demonstrate the mathematical model is suitable for the real situation which can reduce the fixing error effectively.