全圆连续角度标准装置的系统误差分离与补偿

System error separation and compensation of the continuous full circle angle standard device

中国计量科学研究院自主研发了全圆(0°~360°)连续角度标准装置,该标准装置采用四读数头等分平均(EDA)的自校准方法进行硬件补偿,补偿后的测角精度优于0.1″。为了进一步提高该标准装置的测角精度,本文首先基于误差特征从谐波角度推导自校准误差分离算法数学模型,提出利用全组合和EDA混合测量校准的误差分离方法;其次量化分析全组合分离的原始误差与EDA补偿后的全圆离散角位置偏差傅里叶级数各阶次分布,分析EDA补偿后误差的衰减率获得EDA最优补偿函数,并利用傅里叶逆变换法生成(0°~360°)全圆连续角度补偿函数;最后利用激光干涉仪对全圆连续角度标准进行小角度范围内的测角精度验证,同时与中国计量科学研究院的激光小角度基准进行比对验证。实验结果表明该方法利用全组合离线的高精度测量能力,使补偿后的EDA测角精度在全圆连续角度范围内逼近全组合方法,改善了自校准的校准能力及局限性,进一步优化了全圆连续角度标准装置。

A continuous angle standard device for the full circle(0°~360°) is developed at the National Institute of Metrology, China. The self-calibration method of equal division average(EDA) with four reading heads is utilized for hardware compensation. The angle measurement accuracy of the standard device after compensation is smaller than 0.1″. To further improve the angle measurement accuracy of the standard device, the mathematical model of the self-calibration error separation algorithm is derived from the harmonic angle based on the error characteristics, and the error separation method based on cross-calibration and the EDA method is proposed. Secondly, the Fourier series distribution of the original error of full combination separation and the full circle discrete angular position deviation after EDA compensation is analyzed quantitatively. And the error attenuation rate after EDA compensation is analyzed to achieve the optimal EDA compensation function. The inverse Fourier transform method is used to generate the continuous full circle(0°~360°) angle compensation function. Finally, the laser interferometer is utilized to verify the accuracy of the full circle continuous angle standard in the small angle range, which is compared with the laser small angle benchmark of National Institute of Metrology. Experimental results show that the proposed method takes advantage of the high-precision measurement capability of the cross-calibration off-line. The compensated EDA angle measurement accuracy is close to the cross-calibration method within the continuous angle range of the full circle. This method can improve the calibration capability and limitations of self-calibration. The continuous full circle angle standard device is further improved.