Method of Acquiring Initial Attitude for Lunar Soft Landing Ground Test Using Strapdown Inertial Navigation

Abstract

The invention discloses an initial attitude acquisition method for a ground test for soft lunar landing by using a SINS (serial inertial navigation system), and belongs to the field of lunar exploration. The method comprises the following specific steps: firstly, arranging a fixed azimuth mirror near a test field, and by adopting the azimuth mirror for buffering, obtaining an attitude transformation matrix of a tester control coordinate system relative to a sky northeast coordinate system of the test field; then, through a geographical latitude of an observation point of the test field, obtaining a transformation matrix of the sky northeast coordinate system of the test field relative to a geocentric coordinate system, so that a transformation matrix C6 of the tester control coordinate system relative to the geocentric coordinate system is obtained, and then an attitude Q0 quaternion at an initial time T0 is obtained finally; starting from the initial time T0, carrying out attitude extrapolation by using gyro measurement data; and obtaining an attitude Qk during a k(th) control period, carrying out real-time output on the Qk until the tester attitude extrapolation process is completed and a landing test begins, wherein the Qk at the moment is taken as an initial attitude of a tester. The method disclosed by the invention is applicable to the ground test for lunar landing.

Description

Technical field [0001] The invention relates to the field of lunar exploration, in particular to a real-time acquisition method of initial attitude for lunar soft landing ground test using strap-down inertial navigation. Background technique [0002] For the currently more commonly used lunar soft landing missions using strapdown inertial navigation, if the feasibility of the process control scheme and the function and performance of the equipment are to be verified, it is necessary to carry out corresponding ground tests. [0003] At the beginning of the ground test, it is necessary to obtain the initial attitude (ie attitude reference) of the tester to complete the subsequent autonomous guidance, navigation and control tasks. The attitude of the tester represents the three-axis direction of the control coordinate system of the tester. The coordinate system is an inertial principal axis coordinate system centered at the center of mass. [0004] In actual orbital lunar soft landing ...

AI Technical Summary

Problems solved by technology

Since the tester is initially at a high altitude during the test, it is difficult to set up measurement equipment at high altitude and close range

Usually, the feasible method is to fix the target on the tester, use the total station on the ground to measure the relative position relationship between the target on the tester and the coordinate system of the test field at a distance, so as to calculate the relative attitude of the tester relative to the coordinate system of the test site, and then Combining the relative relationship between the test site coordinate system and the test site's local sky northeast coordinate system for further conversion, the relationship between the test device and the test field local sky northeast coordinate system can be obtained. The above method has many conversion steps, and the long-distance measurement position relationship is used to calculate the attitude The error is large, and the final initial attitude accuracy cannot meet the test requirements

[0009] In addition, due to the time difference between the end time of the initial attitude measurement, the time when the attitude data injector is uploaded, and the start time of the test, the attitude at the start time of the test is different from the measurement time due to the influence of natural wind and other factors, resulting in the injected initial attitude and the time when the test starts to navigate. There is a large deviation in attitude

[0010] Therefore, there is currently no effective method to obtain a high-precision initial attitude in real time in the lunar soft landing test

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