时栅传感器定距变换与误差频率扫描自标定法

时栅传感器在特殊恶劣环境中应用,面临安装偏差、电气参数偏移、外部导磁介质介入引起电磁场畸变等因素的影响,导致测量精度下降。现场又缺乏提供高精度参考基准的条件,无法实施在线标定。针对这一问题,本文提出利用两个相隔恒定间距测量值函数求解误差函数频谱的算式(定义为定距变换),并据此设计了一种基于定距变换的误差频率扫描自标定方法。该方法通过合理的间距组合,可对包含有限频率成分误差的时栅传感器实施误差频谱扫描,重构误差函数,在无参考标准器的前提下实现传感器的在线自标定。在此基础上,研制样机进行自标定和比对实验。实验结果表明:由于安装偏差和电气参数偏移引起±40″测量误差的时栅传感器,在实施误差频率扫描自标定后与参考标准器进行比对,二者差异小于0.7″。本研究为时栅传感器进一步提高测量精度以及在特殊环境的应用中保持精度提供了有效的解决方案和可靠的理论依据。

Fixed distance transform and error frequency scanning self-calibration method for time grating sensor

Time grating sensor is usually applied in extreme severe environment, there exist the influences of mounting error, electrical parameter deviation, electro magnetic field distortion caused by external magnetic medium and etc., which leads to the measurement accuracy declining. Moreover, there is a lack of high precision reference standard in the working site, it is difficult to calibrate the sensor online. Aiming at this problem, in this paper an algorithm is proposed, which employs the measurement results of the sensor in two positions with a fixed distance (named fixed distance transform) to calculate the error frequencies, and an error frequency scanning self-calibration method based on fixed distance transform is designed. The method can enable the time grating sensor to perform error frequency scanning and reconstruct error function when the sensor contains the error with finite frequency components and if the sensor position interval is appropriate. Thus, the sensor online self calibration is achieved without using any reference standard. Based on above, a prototype was developed, experiments on self-calibration and comparison with reference standard were conducted. Experiment results show that for the time grating sensor with ±40 arc-seconds measurement error caused by mounting error and electrical parameter deviation, there is only 0.7 arc-second difference left compared with the reference standard after the sensor prototype is calibrated with the error frequency scanning self-calibration method. The study in this paper provides a feasible solution scheme and reliable theory foundation for further improving the measurement accuracy of time grating sensor and maintaining its accuracy in the applications under extreme severe environment.