Optimal Calibration Method of PIGA’s Orthogonal Poses for Gravity Field Testing

Abstract

With the increasing requirements for accuracy of pendulous integrating gyroscopic accelerometer (PIGA), the key to the development of accuracy of PIGA is the advanced calibration methods. This paper focuses on the calibration method of the main error coefficients of PIGA on the indexing head table. The precise input accelerations and angular velocities are deduced and the complete error calibration model is established based on the corresponding coordinate systems. Then, the orthogonal 4-pose calibration method of dual PIGAs is proposed to identify the harmonic term coefficients of angle error. The calibration uncertainty and efficiency of equal angle sequency and equal acceleration sequency calibration schemes are analyzed. Then, the optimal calibration method is proposed and the complete test process is designed, which can accurately and efficiently calibrate PIGA by compensating with the angle error and combining the two different sequency schemes. Simulation results show that 22-position equal acceleration sequency scheme can calibrate bias and scale factor more accurately and the test cost of equal angle sequency scheme is lower. After compensation with angle error, the magnitudes of calibration uncertainties are decreased from 10−6 to 10−7 and the maximum value of relative fitting accuracy is decreased from 6.6 × 10−5 to 2.7 × 10−5 g by the proposed 22-position optimal calibration method.