An improved comprehensive calibration method for ship strapdown inertial navigation system

Abstract

To restrain the divergence of positioning errors in inertial navigation systems (INSs) and improve long-term navigation and positioning accuracies, comprehensive calibration technology is an important method. This paper improves on the basis of the previous method of determining the misalignment angles and equivalent gyroscope drift by the parameters identification method (PIM), and introduces the normal time-frequency transform (NTFT) method. The main work of this paper are as follows: (1) the relationship between the Schuler period oscillation (SPO) in the INS velocity and the misalignment angles are analyzed, and then the misalignment angles are calculated with the extracted velocity using NTFT; (2) PIM and NTFT are combined for comprehensive calibration, the attitude angles, velocities and latitude are reset, and the longitude is compensated with the equivalent gyroscope drift. Simulation and shipboard dynamic tests show that the NTFT/PIM can effectively restrain the amplitude of SPO error and improve the long-term navigation and positioning accuracies. From the perspective of practical application, the result of this study is a single-point calibration technology that improves the autonomy of the system.