A Transfer Alignment Algorithm Based on Grading Correction With Large Misalignment Angle

During the transfer alignment process, due to the unknown large installation angle between the main and secondary inertial navigation systems (INSs), nonlinear problems may occur, seriously deteriorating the accuracy of transfer alignment. To address this issue, we propose a transfer alignment method based on graded correction of large misalignment angles. First, we designed a coarse alignment algorithm based on singular value decomposition to estimate the approximate installation angle. Second, a virtual secondary INS framework is used to convert the original large misalignment angle into a small one. Finally, the virtual secondary INS is corrected using the fine alignment method, and then rotated back to the real secondary INS framework. Simulation and field test results show that the proposed algorithm achieves alignment accuracy better than 0.05°. Compared with common nonlinear transfer alignment algorithms, our method simplifies the complexity of the algorithm, significantly improves alignment accuracy and application reliability.