High-Precision Calibration Method of Inclinometer for Coal Mine Based on Improved Ellipsoid Fitting

The inclinometer for coal mine is limited by the downhole drilling conditions, it usually composed of magnetic sensor and MEMS accelerometer, and the drilling trajectory parameters can be solved through the principle of inclination principle. However, in fact, due to the existence of various errors, before the inclinometer is used, it must be calibrated to correct the error. The traditional method is ellipsoid fitting, which can quickly meet the error compensation of three-dimensional space, but there is a problem of algorithm instability caused by constraint matrix singularity during solution, and the compensation effect is limited. In this paper, an improved ellipsoid fitting calibration algorithm is proposed to solve the above problems and to Secondary compensate for the remaining angle error. The result is that the root mean square error of azimuth angle is reduced from 9.72° to 0.86°, which shows that the improved ellipsoid fitting method has significantly improved the measurement accuracy of the inclinometer.