Initial alignment method suitable for rocking base

Abstract

The invention provides an initial alignment method suitable for a rocking base. The method comprises the following steps: synchronously collecting the angular rate information of a three-axis gyro and the specific force information of a three-axis accelerometer at real time when a base is influenced by rocking interference; carrying out coarse alignment; obtaining the transformation relationship between a carrier coordinate system and a semi-fixed coordinate system according to the navigation, horizontal rocking and transverse rocking information input by an inertial navigator; projecting the acceleration information in the carrier coordinate system onto the three axis of the semi-fixed coordinate system, and carrying out integration; processing signals by a high-pass digital filter; selecting the extracted ship instantaneous linear movement speed information as the speed reference, reducing the extracted speed by a speed calculated by the inertial navigator to obtain the difference, and building a state equation and a measurement equation of a Kalman filter by taking the difference as the measurement value of the Kalman filter; and discretizing the Kalman filter to complete alignment. The initial alignment method provided by the invention has the advantages of shorter alignment time, higher alignment precision, and higher environment adaptability in comparison with an alignment method using position error as the measurement value.

Description

Technical field [0001] The invention relates to an initial alignment method of a strapdown inertial navigation system for ships, in particular to an initial alignment method suitable for a rocking base. Background technique [0002] Compared with spacecraft and aircraft, the simultaneous existence of ship swaying and shaking (also known as "instant line motion") is a unique and severe state of motion. Under the condition of the instantaneous linear motion base, GPS and Doppler log cannot provide accurate instantaneous linear velocity information of the carrier, resulting in inaccurate measurement (ie velocity information) in the Kalman filter alignment process. If you ignore the instantaneous line motion, it will have a great impact on the initial alignment. [0003] For swaying, the inertial navigation system must first generate angular velocity input, which will cause the attitude matrix in the mathematical platform Changes, but It should change with the swing. So no matter h...

AI Technical Summary

Problems solved by technology

For this kind of instantaneous line motion, there is no good measurement method in China at present (the speed measurement error of Doppler Log (DVL) and GPS in the mooring state is very large), which leads to the error in the Kalman filter alignment process. The measurement error of the velocity quantity is very large. For the Kalman filter method based on the white noise error model, it is equivalent to introducing colored noise with a large amplitude in the quantity measurement, which makes the final estimation result diverge.

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