转台工作面角位置测量装置误差分析与补偿

Error analysis and compensation of angular position measuring device for turntable working surface

针对特定转台轴端角位置检测误差不能反映实际产品工作面空间角位置的问题,介绍了一种以圆光栅和水平电容传感器作为测角元件的转台工作面空间角位置定位测量装置。以提高空间测角精度为目的,重点对装置各项误差因素进行归类分析。除光栅和传感器分别存在的分系统测角误差外,测量装置还存在转轴与测量基面不平行、传感器敏感轴与测量基面不平行等误差项。为修正测角系统误差,根据圆光栅旋转面、传感器敏感轴、转轴轴系、测量基面的空间几何关系建立数学模型,分析系统误差影响因素。最后利用分度误差在0.3″高精度转台对校准装置进行标定,并利用径向基函数(RBF)神经网络建立误差补偿模型,对系统测角精度进行修正,使系统最大误差值由13.75″下降至2.9″,满足了3″以内的测角精度需求。

The detection of angular positioning error on specific turntable shaft end cannot reflect its actual space angular position of working surface. Thus, a space angular position measuring device of turntable working surface is introduced with circular grating and horizontal capacitance sensor as its angle measuring components. The error factors of the measuring device are especially classified and analyzed in order to improve spatial angle measurement accuracy. Besides the angle measuring error of subsystem, the measuring device has error that the shafting or the sensitive direction of horizontal capacitance sensor is not parallel to the reference plane for measurement and others error terms. The mathematical model is established to analyze the factors of systematic errors and correct them according to the spatial geometrical relations of grating rotary surface, sensitive direction of sensor, rotation axis and reference plane for measurement. Then the measuring device is calibrated by using high-precision turntable with 0.3＂ indexing error. And the mathematical model of error compensation is established based on radial basis function （RBF） neural network to improve precision with the maximum error value decreased to 2.9 ＂ from 13.75 ＂ to satisfy angular measuring accuracy within 3 ＂ demand.