阅读说明：本技术 一种基于天文导航原理的捷联惯导坐标系动态取齐方法 (Strapdown inertial navigation coordinate system dynamic alignment method based on astronomical navigation principle ) 是由 刘新明 赵李健 周海渊 徐如祥 周建 吴红兵 孔祥龙 李可 于 2020-05-09 设计创作，主要内容包括：本发明涉及一种基于天文导航原理的捷联惯性导航设备姿态动态精度鉴定方法,方法包括以下步骤：一是利用经纬仪获取恒星实测指向；二是通过提取星库数据计算恒星理论指向；三是通过坐标转换获取恒星实测指向和理论指向之间的误差；四是修正误差实现捷联惯导的坐标取齐。本发明建立一种基于天文导航原理的捷联惯导坐标系动态取齐方法,打破了捷联惯导坐标取齐需要静态的局限,解决了捷联惯导坐标取齐周期长、耗资大的难题,该方法可以在动态条件下实现捷联惯导坐标取齐,使用灵活而且经济实惠。(The invention relates to a strapdown inertial navigation equipment attitude dynamic precision identification method based on an astronomical navigation principle, which comprises the following steps: firstly, acquiring actually measured directions of fixed stars by using a theodolite; secondly, calculating the fixed star theoretical direction by extracting star database data; thirdly, acquiring an error between an actually measured direction and a theoretical direction of the fixed star through coordinate conversion; and fourthly, correcting errors to achieve coordinate alignment of strapdown inertial navigation. The invention establishes a strapdown inertial navigation coordinate system dynamic alignment method based on the astronomical navigation principle, breaks through the limitation that the strapdown inertial navigation coordinate alignment needs to be static, solves the problems of long alignment period and high cost of the strapdown inertial navigation coordinate, can realize the strapdown inertial navigation coordinate alignment under the dynamic condition, and is flexible to use and economical and practical.)

1. A strapdown inertial navigation coordinate system dynamic alignment method based on an astronomical navigation principle is characterized by comprising the following steps: the method comprises the following steps:

step one, acquiring actually measured direction of fixed star by using theodolite

1) Direct measurement value A' of photoelectric theodolite_ij、E″_ijThe method is synthesized by two parts of encoder output and miss amount output, namely:

A″_ij＝A″_ijcode + A_ijOff-target; e ″)_ij＝E″_ijCode + E_ijMiss (1)

2) For A ″)_ij、E″_ijCorrecting shafting difference and zero difference to obtain the azimuth A 'of the i star point on the electro-optic theodolite deck system'_ijAnd a pitch angle E'_ijNamely:

wherein: a. the₀、E₀Is azimuth and pitching zero position; c is the collimation difference; a. the_mIs the vertical axis difference amplitude; a. the_HThe direction of maximum inclination of the vertical axis difference; b is the difference of the horizontal axis.

3) Noting the i star pointThe sampling time of the jth sampling point is t_ijThen t is_ijPointing direction of i-star point at moment in ship body coordinate systemCan be prepared from A'_ij、E′_ijExpressed as:

step two, calculating the fixed star theoretical direction by extracting star database data

1)t_ijTheoretical azimuth angle of i-star point at moment in ship body coordinate systemPitch angleThe three-dimensional meridian α_ijCelestial sphere declination_ijLongitude lambda of star point_ijLatitude of star measuring point

wherein: tau is_ijIs the local hour angle of the i star point; the celestial red channels and celestial red latitudes of the i star points can be found in the astronomical calendar;

2) theoretical azimuth angle according to formula (4)

step three, acquiring actual measurement and theoretical pointing errors of fixed stars through coordinate conversion

1) The conversion relationship according to the coordinate system is as follows:

recording the strapdown inertial navigation coordinate system as a b' system, and expressing the output attitude matrix asAttitude matrix of hull coordinate systemCan be output by

2) substituting the formula (7) into the formula (6) to obtain:

wherein:are all known data;describing the deviation of a strapdown inertial navigation coordinate system and a ship body coordinate system;

step four, correcting errors to achieve coordinate alignment of strapdown inertial navigation

1) And (3) substituting the multiple groups of measurement data into a formula (8) to obtain a simultaneous equation:

therefore, the temperature of the molten metal is controlled,can be expressed as:

Technical Field

The invention relates to a strapdown inertial navigation coordinate system dynamic alignment method based on an astronomical navigation principle. Belongs to the technical field of inertial navigation.

Background

The strapdown inertial navigation provides accurate attitude information for the space survey ship and provides coordinate reference data for the ship body. As a coordinate reference, the equipment needs to be used after coordinate alignment, but the current coordinate alignment means is very inconvenient.

Traditionally, maintenance of the hull has been combined and performed in a static situation where the vessel enters the docking station. The cost of the ship entering the dock pier is huge on one hand, and the period is long on the other hand, so that the ship has an opportunity for several years. Coordinate alignment under the docking static condition can not meet the alignment requirement of a strapdown inertial navigation coordinate system in both the economic effect and the time effect.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a strapdown inertial navigation coordinate system dynamic alignment method based on an astronomical navigation principle aiming at the prior art, which can finish the alignment of the strapdown inertial navigation coordinate system under a dynamic condition.

The technical scheme adopted by the invention for solving the problems is as follows: a strapdown inertial navigation coordinate system dynamic alignment method based on an astronomical navigation principle comprises the following steps:

step one, acquiring actually measured direction of fixed star by using theodolite

1) Direct measurement value A' of photoelectric theodolite_ij、E″_ijThe method is synthesized by two parts of encoder output and miss amount output, namely:

A″_ij＝A″_ijcode + A_ijOff-target; e ″)_ij＝E″_ijCode + E_ijMiss (1)

2) For A ″)_ij、E″_ijCorrecting the shafting difference and the zero difference to obtain the star iPoint to azimuth angle A 'of electro-optic theodolite deck system'_ijAnd a pitch angle E'_ijNamely:

wherein: a. the₀、E₀Is azimuth and pitching zero position; c is the collimation difference; a. the_mIs the vertical axis difference amplitude; a. the_HThe direction of maximum inclination of the vertical axis difference; b is the difference of the horizontal axis.

3) Let the sampling time of the j sampling point of the i star point be t_ijThen t is_ijPointing direction of i-star point at moment in ship body coordinate systemCan be prepared from A'_ij、E′_ijExpressed as:

step two, calculating the fixed star theoretical direction by extracting star database data

1)t_ijTheoretical azimuth angle of i-star point at moment in ship body coordinate systemPitch angle

The three-dimensional meridian α_ijCelestial sphere declination_ijLongitude lambda of star point_ijLatitude of star measuring pointAt time of local t'_ijAnd accurately calculating to obtain:

wherein: tau is_ijIs the local hour angle of the i star point; the celestial sphere with the i stars and the three meridiansThe declination can be found in the astronomical calendar;

2) theoretical azimuth angle according to formula (4)Pitch angle

Can be used for converting t_ijThe real pointing direction of the star point at time i in the geographic coordinate system is represented as:

step three, acquiring actual measurement and theoretical pointing errors of fixed stars through coordinate conversion

1) The conversion relationship according to the coordinate system is as follows:

recording the strapdown inertial navigation coordinate system as a b' system, and expressing the output attitude matrix as

Attitude matrix of hull coordinate systemCan be output byExpressed as:

2) substituting the formula (7) into the formula (6) to obtain:

wherein:are all known data;describing the deviation of a strapdown inertial navigation coordinate system and a ship body coordinate system;

step four, correcting errors to achieve coordinate alignment of strapdown inertial navigation

1) And (3) substituting the multiple groups of measurement data into a formula (8) to obtain a simultaneous equation:

therefore, the temperature of the molten metal is controlled,can be expressed as:

namely a coordinate system deviation matrix of the strapdown inertial navigation, and a solution is obtained.

Compared with the prior art, the invention has the advantages that:

the invention establishes a strapdown inertial navigation coordinate system dynamic alignment method based on the astronomical navigation principle, breaks through the limitation that the strapdown inertial navigation coordinate alignment needs to be static, solves the problems of long alignment period and high cost of the strapdown inertial navigation coordinate, can realize the strapdown inertial navigation coordinate alignment under the dynamic condition, and is flexible to use and economical and practical. The method mainly comprises the steps of obtaining a fixed star actual measurement pointing direction, calculating a fixed star theoretical pointing direction, converting fixed star actual measurement pointing direction and theoretical pointing coordinate and correcting coordinate alignment errors.

Drawings

FIG. 1 is a diagram illustrating the error review of the strapdown inertial navigation pitch angle after accurate alignment according to an embodiment of the present invention.

FIG. 2 is a diagram for rechecking the errors of the strapdown inertial navigation yaw angles after accurate alignment in the embodiment of the invention.

FIG. 3 is a diagram for rechecking the course angle error of strapdown inertial navigation after accurate alignment in the embodiment of the invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

The embodiment is a method for aligning a dynamic strapdown inertial navigation coordinate system, which comprises the following steps: firstly, acquiring actually measured directions of fixed stars; secondly, acquiring the theoretical orientation of the fixed star; thirdly, coordinate matrix conversion; and fourthly, coordinate alignment realization.

Second, the implementation process

Under the condition of wharf mooring or ship navigation, the strapdown inertial navigation (fixedly connected with the photoelectric theodolite base) is used for guiding the photoelectric theodolite to measure the fixed star, so that the strapdown inertial navigation coordinate system is accurately aligned.

The implementation process is as follows: starting up the strapdown inertial navigation equipment, measuring n stars with elevation angles between 20 and 60 degrees and approximately consistent azimuth intervals by using a strapdown inertial navigation servo photoelectric theodolite, recording m groups of data by each star, and obtaining an actual observation value A' of each star in a theodolite measurement system_ij、E″_ijAnd (i represents an asterisk; j represents a sampling number), and synchronously recording the time of the sampling moment, the ship position and the attitude angle information output value of the strapdown inertial navigation.

In order to inhibit the influence of the measurement error of the theodolite, the number of stars of each set of the surveyors is required to be more and uniformly distributed in all directions as much as possible; in order to reduce the influence of attitude measurement errors of the strapdown inertial navigation, repeated star measurement is required to be carried out for 1-2 days after the strapdown inertial navigation works stably, and the star measurement intervals are uniform as much as possible. The specific operating points are given below:

1. after the strapdown inertial navigation system is started for 8 hours, guiding the electro-optic theodolite to measure stars at intervals of about 2-4 hours by utilizing the strapdown inertial navigation;

2. selecting more than 16 stars during star measurement, and uniformly distributing the stars as much as possible, wherein each quadrant has more than 4 stars;

3. carrying out effective star measurement for more than 10 times in total; if the actual number of the stars is less than 10 or 1 or more quadrants have no stars detected, the star is considered invalid;

4. and (3) carrying out a star measurement test after the coordinate system is accurately aligned: and (3) utilizing the strapdown inertial navigation to guide the theodolite to carry out 1-time satellite surveying, calculating the attitude angle error of the strapdown inertial navigation after the satellite surveying is finished, and if the horizontal error is less than 10 ' and the azimuth error is less than 20 ' -30 ', determining that the coordinate alignment result is effective.