Drilling Tool Attitude Dynamic Measurement Algorithm Based on Composite Inertial Measurement Unit

Drilling tool attitude parameters are crucial for achieving precise directional drilling and trajectory control. Navigation systems based on redundant micro-electro-mechanical systems inertial measurement units (MEMS-IMU) significantly improve the reliability and accuracy of drilling tool attitude measurements. To achieve redundant arrangement of MEMS-IMUs, this paper proposes uniformly arranging MEMS-IMUs on a hollow hexagonal prism carrier, taking into account the actual structure of the drilling tool. However, under dynamic conditions, when updating drilling tool attitude using the strapdown inertial navigation system (SINS), the nonlinear errors of the MEMS-IMU accumulate over time, leading to distortion in the attitude calculation results. Therefore, this paper proposes a composite inertial measurement unit (CIMU) attitude measurement method. A virtual inertial measurement unit (VIMU) is generated through multi-IMU data fusion. Furthermore, the geometric constraints between each IMU and the VIMU, combined with Kalman filtering, are used to achieve real-time suppression of attitude errors, thereby improving the accuracy of the drilling tool attitude calculation results. Experimental results show that, compared with conventional data fusion methods, the CIMU algorithm reduces the overall drilling tool attitude error level by 40–70%.