中文摘要：

介绍了使用激光测距传感器配合球面二自由度并联机构测量大锻件尺寸的方法。分析了定坐标系下锻件上被测量点的三维坐标。锻压过程中的轴类锻件轴向断面仍可以近似视为圆,而斜向的截面形状为椭圆。本文把斜截面向轴向截面投影,并采用最小二乘法来拟合锻件的轴向截面,进而求出轴向截面的尺寸参数（包括中心坐标,半径,和圆方程的系数）。最后通过实验得出这种处理是可行和可靠的。

英文摘要：

This paper introduces a new online method to measure the dimension of large forgings, which uses the pulsed laser ranging sensor with a 2-DOF parallel spherical mechanism. In the paper the measuring point＇s coordinate in the fixed coordinates system is analyzed. In the course of forging press, the axial cross section of shaft forgings can still be seen as circle approximately. The shapes of the oblique section are ellipse. The ellipses which are on the oblique sections are projected to the axial cross sections and the least squares technique is adopted to fit the axial cross section of the shaft forgings, and then the parameters of the section, which include the center coordinate, the radius, the coefficients of circle＇s equation, can be worked out by the process presented in the article. In the end, experiments are conducted to test the method, and the results verified the efficiency of this method.