A bi-vector calibrated algorithm of fiber optic gyroscopes aided magnetometers based on inclinometer

Inclinometers based on magnetometers are widely applied in oil and gas well measurements and have poor anti-interference ability. Affected by the drilling tools and stratum, the magnetized inclinometer will cause the output deviation of three-axis magnetometer. Therefore, periodic calibration before engineering applications is a necessary operation process. Fiber optic gyroscopes, with their characteristics of high precision and anti-interference, complement the advantages of magnetometers, which have improved the precision and reliability of the borehole attitude. In addition, a navigation grade three-axis fiber optic gyroscope provides convenience for periodic calibration of magnetometer. Consequently, a bi-vector field correction method based on a fiber-optic gyroscope and magnetometer inclinometer is presented in this study. First, the geometric relation between the seven elements of the geomagnetic field and Earth's angular velocity was deduced with reference to the right-hand criterion. Second, a bi-vector field error compensation model was established. Finally, the simulation and experimental results demonstrated the effectiveness of the proposed calibration method.