Augmented fast orthogonal search/kalman filtering (FOS/KF) positioning and orientation solution using MEMS-based inertial navigation system (INS) in drilling applications

Due to the advantages of small size and low cost, micro-electro-mechanical system (MEMS) inertial navigation systems (INS) show good prospects for use as a part of measurement-while-drilling (MWD) equipment to guarantee proper directional drilling procedure. Since current MEMS sensors have inaccurate measurements, an update aiding solution is developed using the Kalman filtering (KF) technique. However, because of the inherent poor behavior of MEMS sensors, KF technique with its linearized models has limited capability in providing accurate solution through the entire surveying process. In addition, certain realistic problems from the rugged environment would interrupt the updates in KF, without which the performance of the inertial system would deteriorate badly. This research proposes a fast orthogonal search (FOS)/KF solution where the FOS (a nonlinear modeling technique) method is proposed to augment KF. The experimental results illustrate that the FOS/KF solution outperforms the KF-only solution. Velocity and position performance are greatly enhanced during the interruptions of measurement updates.