EKF (extended Kalman filter)-based alignment method for inertia/polarized light integrated navigation system under large misalignment angle

Abstract

The invention relates to an EKF (extended Kalman filter)-based alignment method for an inertia / polarized light integrated navigation system under a large misalignment angle. According to the method, the state vectors of the initial alignment of the inertia / polarized light integrated navigation system are selected to build the nonlinear error state equation of the inertia / polarized light integratednavigation system under the large misalignment angle; a solar vector is calculated according to a polarization azimuth angle measured by a polarized light sensor, and a polarized light nonlinear measurement equation is established; a speed error measurement equation is established according to the speed output of an inertial navigation system; the unified nonlinear measurement equation of the inertia / polarized light integrated navigation system is established by using an augmentation technology; the nonlinear equation of the inertia / polarized light integrated navigation system is discretized;an extended Kalman filter is designed to estimate the error states such as misalignment angle, speed error, gyroscopic drift and accelerometer constant bias of the inertia / polarized light integratednavigation system; feedback correction is carried out on the attitude and speed of the inertia / polarized light integrated navigation system, and the initial alignment estimation precision and speed ofthe inertia / polarized light integrated navigation system under the large misalignment angle are improved. The method has the advantages of high precision, high speed and high autonomy.

Description

technical field [0001] The invention relates to an EKF alignment method of an inertial / polarized light integrated navigation system at a large misalignment angle, which can effectively improve the initial alignment accuracy of a static base of a ground carrier in the earth's atmosphere at a large misalignment angle, and shorten the initial alignment time. Background technique [0002] Navigation is a key technology in the fields of aviation, aerospace, navigation and ground transportation. Since navigation is an integral process, the initial state has a great influence on its accuracy. In order to improve the accuracy of navigation positioning and constant speed, the navigation system needs to perform initial alignment before entering the navigation state. Accurately obtain initial navigation parameters, including attitude, velocity and position information, through initial alignment. Under the static base condition, the vehicle remains stationary, at this time the veloci...

AI Technical Summary

Problems solved by technology

The problem with this method is that only the speed error is used as the measurement information, which makes the eastward gyro drift unsatisfactory, and the alignment of the celestial misalignment angle coupled with it is slow, the alignment time is long, and the alignment accuracy is low

But when the gyro accuracy is low, its output is greatly affected by noise, which will seriously affect its alignment accuracy

Therefore, in order to overcome the shortcomings of a single sensor, the inertial navigation system can form an integrated navigation system with other sensors such as satellites, magnetic compass and star sensors for initial alignment. Additional measurement cannot be provided under the seat, so the accuracy of the initial alignment under the static base is not greatly improved; the magnetic compass is subject to greater electromagnetic interference, and its robustness is poor. When the surrounding magnetic field is abnormal, there will be a large error. The alignment effect in the initial alignment is not very good; the star sensor can estimate the attitude error of the vehicle with high precision, but it is expensive and not suitable for the initial alignment of the static base during the daytime period in the earth's atmosphere

In the invention patent No. 201310069511.4 "A method for initial alignment of the moving base of a SINS / GPS / polarized light integrated navigation system", only one polarized light sensor is used to obtain the polarization measurement, and the calculation process is relatively cumbersome. At the same time, there is division, which will cause the noise to not satisfy the Gaussian distribution, resulting in poor filtering results

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