A linear alignment method for large azimuth misalignment angles based on additive quaternions

Abstract

The invention relates to a large azimuth misalignment angle aligning method based on additive quaternion. The method comprises the following steps: (1) according to a state equation and an observation equation of coarse alignment, by utilizing GPS observation information and linear Kalman filtering, carrying out coarse alignment; (2) in a sliding window, by utilizing the provided threshold conditions, directly calculating the convergence level of a current course angle through additive quaternion, judging whether the course angle completely satisfies the threshold conditions or not, if the result is positive, storing the system covariance information, carrying out fine alignment; and if the result is negative, carrying out coarse alignment (step (1)); and (3) keeping on the system state variable and position of coarse alignment, gesture error equation and observation equation, using a new speed error equation, taking the stored covariance matrix as the primary condition, and carrying out fine alignment, wherein the fine alignment can enter the convergence state rapidly until the alignment reaches an expected level. The provided method can realize stable model switch and satisfies the total state application conditions, and the calculation is simple.

Description

technical field [0001] The invention relates to a linear alignment method for large azimuth misalignment angles based on additive quaternions, and belongs to the technical field of inertial navigation. Background technique [0002] Initial alignment is a key technology of inertial navigation and one of the key technologies of INS / GNSS integrated navigation. In the MEMS-INS / GNSS integrated navigation system, due to the limitations of MEMS devices, especially the gyroscope, it is impossible to initialize the azimuth misalignment angle through self-alignment, resulting in a large azimuth misalignment angle problem. One of the solutions The method is to directly align the moving base. [0003] Establishing accurate INS error propagation equations and adopting appropriate filtering techniques are the main issues for initial alignment. In the case of a large azimuth misalignment angle, the alignment model of the moving base is nonlinear in nature, and the nonlinear filtering met...

AI Technical Summary

Problems solved by technology

[0009] The invention solves the problem: it overcomes the problem that the rough alignment and fine alignment models of the Euler angle method are not stable in the prior art, and the filtering model of the quaternion method is nonlinear, and provides a method based on additive quaternion The large azimuth misalignment angle linear alignment method can not only realize smooth model switching, but also meet the application conditions of all states, and the calculation is simple

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