Non-linear alignment method of strapdown inertial navigation system

Abstract

A non-linear alignment method of a strapdown inertial navigation system comprises the following steps of: acquiring data of an accelerometer and a fiber gyroscope of the fiber strapdown inertial navigation system and carrying out denoise processing, realizing coarse alignment and fine alignment processes by the utilization of an analysis method and a compass method, establishing a quaternion-based strapdown inertial navigation system non-linear error model under the condition that attitude angle and azimuth angle are both large misalignment angles, establishing an observation model with speed as observed quantity, carrying out iterative and filter estimation by the use of an improved UKF algorithm on the basis of the model so as to obtain the misaligned angle of the platform, continuously carrying out closed-loop feedback and correcting attitude matrix of the strapdown inertia system in the previous period, so as to accurately complete the initial alignment process. The method can be used to guarantee safety and confidentiality of the initial alignment without the utilization of other sensor information. By the introduction of the quaternion error based non-linear system error model, linearization is not required to guarantee the precision of the model. Computational complexity is reduced, and filtering is carried out on the established non-linear system so as to complete fine alignment.

Description

technical field [0001] The invention relates to a fast, high-precision, passive non-linear alignment method for a strapdown inertial navigation system, which is particularly suitable for large misalignment angle alignment of the strapdown inertial navigation system. Background technique [0002] In the initial alignment of strapdown inertial navigation, due to the large initial misalignment angle, it is generally necessary to perform rough alignment first, and then use the Kalman filter for fine alignment. Coarse alignment is mainly to perform horizontal alignment. This process can also include azimuth coarse alignment. The accuracy of coarse alignment is low, and the alignment time of initial alignment is prolonged. The mathematical model of the strapdown inertial navigation system is strictly a nonlinear model, and the commonly used ψ equation and linear filtering method can no longer be accurately expressed, so it is necessary to use an accurate nonlinear error model and ...

AI Technical Summary

Problems solved by technology

However, most of the existing technologies are aimed at the alignment situation under small misalignment angles, and even for large misalignment angles, the algorithm is relatively complicated

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