CN109992869A - A calculation method for automatic layout of star sensor - Google Patents

Abstract

An automatic layout calculation method of a star sensor uses the ephemeris or the angle between the yellow and the red to establish a sun point model, and uses the CAD software import method to establish a satellite point model of the satellite body and the satellite components such as the antenna, the solar wing, and the engine plume. The point position and azimuth angle are used to establish the cone angle model of the star sensor's field of view, and the relationship between the sun point model, the satellite point model and the star sensor's field of view cone model is determined by space transformation, so as to output the effective field of view cone angle of the star sensor. By traversing the position and azimuth of the installation point of the star sensor in the layout area, the maximum effective cone angle of the field of view is obtained, thereby outputting the optimal layout position and azimuth.

Description

A calculation method for automatic layout of star sensor

technical field

The invention belongs to the technical field of overall design of spacecraft, and relates to an automatic layout calculation method of a star sensor.

Background technique

With the advancement of science and technology, more and more satellites are equipped with star sensors. By observing the positions of stars on the celestial sphere and comparing them with the star map, the star sensors can determine the satellite's attitude in inertial space, and then combine the satellite orbit information. , the on-orbit attitude of the satellite can be determined. Due to the advantages of high measurement accuracy and long-term use, star sensors, as important attitude measurement components, have obtained a large number of on-orbit applications.

The star sensor is usually fixedly installed with the satellite body. The issue of the star sensor layout refers to where the star sensor is installed on the satellite body and at what azimuth angle. The main goal of the layout of the star sensor is to obtain the largest field of view of the star sensor under the premise of satisfying various constraints.

As the equipment installed on the spacecraft develops in the direction of complexity and diversification, the layout of the star sensor needs to comprehensively consider the constraints such as equipment interference and field occlusion, and the layout becomes more and more difficult. How to quickly find the feasible solution of the star-sensing layout that meets the requirements, and how to find the optimal solution among the feasible solutions flexibly and quickly has important engineering significance.

In the past, the layout of the star sensor was mainly completed manually by the designer. The field of view of the star sensor was established as a cone on the satellite CAD model. The position of the cone was manually placed, and the collision relationship between the cone and other components was judged to determine the star. Whether Min can be laid out in this position.

This method is cumbersome to operate, has low efficiency, and takes up a lot of man-hours. At the same time, because the collision of the viewing cone angle is used as the criterion, the final result given by this method is a certain feasible solution, and the optimal solution cannot be given. On satellites with complex installation conditions, a large number of feasible solutions are often omitted.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art, the present invention proposes an automatic layout calculation method of a star sensor, which realizes the rapid calculation of the layout of the star sensor on the satellite.

The technical scheme adopted by the present invention is: an automatic layout calculation method for a star sensor, comprising the following steps:

1) Using ephemeris and satellite-related parameters, obtain the relative relationship between the sun and the satellite and establish a sun point model;

2) Import the satellite component model information and establish a satellite point model. The imported satellite components include the star body and antenna, solar wing, and engine plume;

3) In the value space, for any given set of star sensor installation positions and azimuth angles, establish a star sensor field of view cone angle model;

4) Based on the spatial coordinate transformation, discriminate the relationship between the sun point model and the field of view cone angle model, the relationship between the satellite point model and the field of view cone angle model, and output the effective field of view cone angle corresponding to the group of installation positions;

5) In the value space, give multiple sets of star sensor installation positions and azimuths in a discretized manner, return to step 3), use the next set of installation positions and azimuths to calculate again, and obtain each group of installation positions in the value space The effective FOV cone angle corresponding to the azimuth angle;

6) Compare all the effective cone angles of the field of view in the value space, and output the installation position and azimuth angle corresponding to the maximum effective cone angle of the field of view as the optimal layout position and azimuth angle.

Described step 1) using ephemeris time to establish a sun point model, the specific steps are: given the starting time, time step, and ending time as input conditions, according to the ephemeris, calculate that the sun is in the J2000 coordinate system at N calculation times The point coordinates are converted to the star body coordinate system, and the converted sun point coordinates are arranged in sequence to form the sun point model A; N is a positive integer.

The step 1) utilizes the angle between the yellow and the red to establish the sun point model, and the specific steps are: given the angle interval, the 360° circumference angle of the equatorial plane is discretized into m parts, and the included angle of the yellow and red is discrete into n parts of the inclination angle, forming m × n sets of direction angles, each set of direction angles calculates a sun position point coordinate, converts the point coordinates to the star body coordinate system, and arranges the converted sun point coordinates to form the sun point model A; m, n are positive integers.

The concrete steps of described step 2) are as follows:

(2.1) Convert the CAD model of the satellite body and the antenna to the STL file represented in the star body coordinate system, read several triangular information matrices composed of point coordinates in the STL file; arrange all the triangular information matrices to form the satellite body , Antenna point model B;

(2.2) By importing the CAD model STL file or manually setting, obtain the point coordinate information matrix of the vertex of the solar wing model in the star body coordinate system, and revolve each point in the point coordinate information matrix around the rotation axis of the solar wing to the set value Rotate 360 degrees at angular intervals to obtain several effective vertex information matrices of solar wings; arrange all effective vertex coordinate information matrices of solar wings to form a solar wing point model C;

(2.3) By manually setting the coordinates of the points on the generatrix of each engine plume cone model, rotate each point 360 degrees around the engine plume jet axis at a set angle interval to obtain the effective boundary of the engine plume point, combine all the effective boundary point coordinate information to obtain the engine plume point model D;

(2.4) Combine the satellite body, the point model B of the antenna, the point model C of the solar wing and the information matrix in the model D of the engine plume point to form the satellite point model E.

In the step (2.1), given a threshold σ, if the distance between two points in a certain triangular information matrix is greater than σ, then insert a number of points on the connection line between the above two points, so that two adjacent points on the line are connected. If the distance between the points is less than σ, the inserted points are added to the triangular information matrix to form a new triangular information matrix.

The concrete steps of described step 3) are as follows:

(3.1) In the value space, given any set of installation position reference points of the star sensor and the azimuth angle of the optical axis of the field of view, and calculate the three-coordinate axis vector of the field of view coordinate system of the star sensor in the star body coordinate system The coordinates in V _x , V _y , V _z ;

(3.2) According to the three-axis vector coordinates, obtain the transformation matrix M from the star body coordinate system to the star sensor field of view coordinate system, M=[V _x , V _y , V _z ] ^T ;

(3.3) According to the transformation matrix M and the origin of the field of view coordinate system of the star sensor, the transformation calculation of the point models A and E from the coordinate system of the star body to the coordinate system of the field of view of the star sensor is performed:

R _l represents the coordinate information matrix of the lth point in point models A and E, is the coordinate information matrix of the lth point in the field of view coordinate system of the star sensor, O _ST is the coordinate information matrix of the origin of the field of view coordinate system; l is a positive integer.

The concrete steps of described step 4) are as follows:

(4.1) Calculation the angle ρ _l with the y-axis of the star sensor's field of view coordinate system;

(4.2) Take the minimum value of the angle _ρj between all points in the point models A and E and the y-axis of the star sensor's field of view coordinate system, and denote it as It is the effective FOV cone angle corresponding to the current group installation position and azimuth angle.

The advantages of the present invention compared with the prior art are:

(1) The present invention provides a layout calculation method and process by using a mathematical expression form, so that the layout process can be fully automated by a computer, which greatly improves the calculation efficiency and reduces the labor cost.

(2) The present invention calculates the corresponding effective field cone angles of all installation positions and azimuth angles in the value space by means of cyclic traversal, so that feasible solutions are no longer omitted, and the global optimal solution can be found.

(3) In the star-sensing layout of the present invention, a point model processing method is uniformly provided for the influence objects of different properties such as the sun, satellite body, antenna, solar wing, plume, etc., and the granularity can be refined by setting a threshold value. , which is convenient for unified calculation and easy expansion.

Description of drawings

FIG. 1 is a flowchart of an automatic layout calculation method of a star sensor according to the present invention.

FIG. 2 is a flowchart of a method for establishing a point model of the sun.

Figure 3 shows the established sun point model.

FIG. 4 is a flowchart of a method for establishing a satellite point model.

Figure 5 shows the established satellite point model.

Fig. 6 is a schematic diagram showing the relationship between the sun point model, the satellite point model and the star sensor's field of view cone angle model through spatial coordinate transformation.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that a more thorough understanding of the present invention will be provided, and will fully convey the scope of the present disclosure to those skilled in the art. It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

FIG. 1 is a flow chart of an automatic layout calculation method of a star sensor according to the present invention. It includes the following steps:

1) Using ephemeris and satellite-related parameters, obtain the relative relationship between the sun and the satellite and establish a sun point model;

2) Import the satellite component model information and establish a satellite point model. The imported satellite components include the star body and antenna, solar wing, and engine plume;

3) In the value space, for a given set of star sensor installation positions and azimuth angles, establish a star sensor field of view cone angle model;

4) Based on the spatial coordinate transformation, discriminate the relationship between the sun point model and the field of view cone angle model, the relationship between the satellite point model and the field of view cone angle model, and output the effective field of view cone angle corresponding to the group of installation positions;

5) In the value space, multiple sets of star sensor installation positions and azimuths are given in a discretized manner, return to step 3, use the next set of installation positions and azimuths and calculate again, and so on, to obtain each group in the value space. The effective cone angle of the field of view corresponding to the installation position and azimuth;

6) Calculate and compare all the effective cone angles of the field of view in the value space, and use the installation position and azimuth angle corresponding to the maximum effective cone angle of the field of view as the optimal layout position and azimuth angle output to complete the automatic layout calculation of the star sensor.

Described step 1), as shown in Figure 2, can be realized by two methods:

Method 1 uses ephemeris time to establish a sun point model. The specific steps are: given the starting time, time step, and ending time as input conditions, and according to the ephemeris, calculate the point coordinates of the sun in the J2000 coordinate system at N calculation times. , and convert the point coordinates to the star body coordinate system, and the matrix formed by arranging the coordinate information of the converted N _A =N points together is the sun point model A. Here, NA is _a positive integer, and the method for converting the point coordinates in the J2000 coordinate system to the star body coordinate system belongs to the common knowledge of those skilled in the art.

If 2017-1-1 00:00:00 is given as the start time, 2017-1-31 00:00:00 is the end time, and 5min is the time step, it is necessary to calculate N _A = 8641 times in total. Sun point coordinates.

The converted coordinate information of each point is represented by [x _i , y _i , z _i ] ^T , where i is the subscript, representing the i-th point; the coordinate information of the points at all times is arranged together to form a matrix, that is is the sun point model, denoted as

Method 2 uses the angle between the yellow and the red to establish the sun point model. The specific steps are: given the angle interval, the 360° circumferential angle of the equatorial plane is discretized into m parts, and the angle between the yellow and red is discrete into n parts of the tilt angle to form m × n groups of directions angle, where m and n are both positive integers, and denote N _A =m×n. The point coordinates of a sun position are calculated by using each set of direction angles, and the point coordinates are converted to the star body coordinate system. The converted coordinate information of N _A points is arranged together to form a matrix, which is the sun point model A. It is common knowledge for those skilled in the art to calculate the coordinates of the sun position point by using the azimuth angle.

If m is equal to 360, n is equal to 80, the angle between yellow and red is ±23.43°. Then, a total of NA ₌ 28800 groups of direction angles need to be calculated. An example of a certain group of direction angles is: the circumference angle is 122°, and the inclination angle is 14.662°. The converted point coordinates are represented by [x _i , y _i , z _i ] ^T , where i is the subscript, representing the ith point; all the point coordinates are arranged together to form a matrix, which is the sun point model A, the format as follows:

An image of the sun point model A is shown in Figure 3.

Described step 2) flow chart as shown in Figure 4, concrete steps are as follows:

(2.1) Use the Catia software to convert the CAD model of the satellite body and the antenna into an STL file represented in the star body coordinate system, and then read the point coordinates and triangle information in the STL file. The STL file contains _NB triangles and 3 Coordinate information of ×N _B points, where N _B is a positive integer. The matrix formed by the information of all points It can be expressed as follows:

Here r is the subscript,

In the formula, each P _r represents a triangle, including the coordinate information of the three vertices of the triangle, which are

[x _r1 ,y _r1 ,z _r1 ] ^T ,[x _r2 ,y _r2 ,z _r2 ] ^T ,[x _r3 ,y _r3 ,z _r3 ] ^T

Given a positive real threshold σ, for the case that the length of a certain side of the triangle in P _r is greater than σ, points are added uniformly on the side of the triangle, so that the distance between adjacent points on the side is less than σ. Take the rth triangle P _r as an example, if the length of the side where [x _r1 ,y _r1 ,z _r1 ] ^T ,[x _r2 ,y _r2 ,z _r2 ] ^T is located is greater than 3σ but less than 4σ, then on this side By adding 3 points evenly, the distance between adjacent points on this side can be less than σ, and the other two sides are similar. After adding points, the matrix representing the information of the triangle is denoted as The format is as follows

The point coordinate information in the formula Represents 3 points obtained by uniformly adding between point 1 ([x _r1 ,y _r1 ,z _r1 ] ^T ) and point 2 ([x _r2 ,y _r2 ,z _r2 ] ^T ), the other two sides are similar .

Arrange all the interpolated triangular information matrices together to obtain the satellite body and antenna point model information matrix B. The format is as follows:

(2.2) Obtain the coordinate information matrix of the vertices of the solar wing model in the star body coordinate system by importing the CAD model STL file or manually setting The format is as follows:

In the formula, t is the subscript, representing the t-th point, Q _t = [a _t , b _t , c _t ] ^T represents the coordinate information of the t-th point, N _c is a positive integer, representing the number of vertices of the solar wing model .

Will Each of the included vertices is rotated 360 degrees around the rotation axis of the solar wing at certain angular intervals to obtain multiple effective vertices of the solar wing. Taking the t-th point Q _t =[a _t ,b _t ,c _t ] ^T as an example, rotate Q _t around the rotation axis of the solar wing by 360° at angular intervals of 30° to generate A total of 12 valid vertices. All valid vertices lie on a surface of revolution. Arrange all valid vertex coordinate information together to obtain the sun wing point model information matrix C, the format is as follows:

(2.3) The coordinate information matrix of the points on the bus line of each engine plume cone model in the star body coordinate system is given by manual setting The format is as follows

In the formula, s is the subscript, representing the sth point, W _s = [e _s , f _s , g _s ] ^T represents the coordinate information of the sth point, N _d is a positive integer, representing the point on the engine plume bus. number.

Will Each point is rotated 360 degrees around the jet axis of the engine plume at certain angular intervals to obtain the effective boundary point of the engine plume. Taking the s-th point W _s =[e _s ,f _s ,g _s ] ^T as an example, rotating W _s around the engine plume injection axis by 60 degrees by 360° at angular intervals will generate W _s ¹ , W _s ² , ...,W _s ⁶ There are a total of 6 effective boundary points, all of which are located on the surface of a body of revolution. Then combine all the effective boundary point coordinate information to obtain the engine plume point model information matrix D, the format is as follows:

D=[W ₁ ,...,W ₂ ,...,W _s ,W _s ¹ ,W _s ² ,...,W _s ⁶ ,W _s+1 ,...]s=1,2 ,...,N _d

(2.4) Arrange the information arrays of the satellite body and the point model B of the antenna, the solar wing point model C, and the engine plume point model D together to form the satellite point model, denoted as E. The image of the point model E=[B,C,D] is shown in Figure 5.

Described step 3) concrete steps are as follows:

(3.1) In the value space, given a set of installation position reference points of the star sensor and the azimuth angle of the optical axis of the field of view (the installation position reference point and azimuth angle are both given in the star body coordinate system), the installation position The coordinate information and pointing azimuth information of the reference point are represented by [α, β, γ] ^T , [θ ₁ , θ ₂ , θ ₃ ] ^T respectively, such as installation position [2.5, 0.65, 0.4] ^T , azimuth angle [45 °,60°,-15°] ^T (azimuth is the angle between the three axes of the star body coordinate system).

Use the installation position and azimuth to establish the field of view coordinate system of the star sensor. The origin of the field of view coordinate system coincides with the reference point of the installation position. The vector directions of the x, y, and z axes of the field of view coordinate system of the star sensor are in the star body. The coordinate information V _x , V _y , and V _z in the coordinate system are calculated as follows:

V _y =[cosθ ₁ ,cosθ ₂ ,cosθ ₃ ] ^T /|[cosθ ₁ ,cosθ ₂ ,cosθ ₃ ] ^T |

V _x =[cosθ ₂ ,-cosθ ₁ ,0] ^T /|[cosθ ₂ ,-cosθ ₁ ,0] ^T |

V _z =V _x ×V _y ;

In the formula, × represents the cross product, and |[cosθ ₂ ,-cosθ ₁ ,0] ^T | represents the modulus of [cosθ ₂ ,-cosθ ₁ ,0] ^T.

(3.2) According to the coordinate information of the three-axis vector direction, the transformation matrix M from the star body coordinate system to the star sensor field of view coordinate system can be obtained:

M=[V _x , V _y , V _z ] ^T

(3.3) According to the transformation matrix M and the origin of the field of view coordinate system of the star sensor, the transformation method of the sun point model A and the satellite point model E from the star body coordinate system to the field of view coordinate system of the star sensor can be obtained.

Here l is the subscript, and R _l represents the coordinate information matrix of the lth point in the point models A and E. is the coordinate information matrix of the point in the field of view coordinate system of the star sensor, O _ST is the coordinate information matrix of the origin of the field of view coordinate system, there is O _ST =[α, β, γ] ^T ; l is a positive integer;

Described step 4) concrete steps are as follows:

(4.1) For any one obtained by the previous step calculate The angle ρ _l with the y-axis of the field of view coordinate system of the star sensor

in the formula for 's model.

(4.2) Take the minimum value of the angle ρ _l between all points in the point models A and E and the y-axis of the star sensor's field of view coordinate system, denoted as That is, the effective cone angle of the field of view corresponding to the installation position of the group and the azimuth angle.

Described step 5) concrete steps are as follows:

In the value space, if there are Ω allowable installation positions (where Ω is a positive integer), the coordinate information matrix of the δth installation position is [α _δ , β _δ , γ _δ ] ^T , at each installation position There are Ψ groups of allowable azimuths (where Ψ is a positive integer), where the first The angle information of each allowable azimuth is Then, the allowable installation points and azimuth angles of the Ω×Ψ group are obtained.

Here δ, Both are subscripts. For each set of allowable installation positions and azimuths, calculate and obtain the effective cone angle of the field of view according to steps 3) and 4), so as to obtain k effective cone angles of the field of view (here k is the footmark).

The step 6) obtains all the effective cone angles of the field of view obtained in step 5) maximum value in The image is shown in Figure 6, and output Corresponding installation location with azimuth As the optimal layout position and azimuth, the automatic layout calculation of the star sensor is completed.

The parts of the present invention that are not described in detail belong to the common knowledge of those skilled in the art.

Claims (7)

1. a star sensor automatic layout calculation method, is characterized in that, comprises the steps as follows: 1) Using ephemeris and satellite-related parameters, obtain the relative relationship between the sun and the satellite and establish a sun point model; 2) Import the satellite component model information and establish a satellite point model. The imported satellite components include the star body and antenna, solar wing, and engine plume; 3) In the value space, for any given set of star sensor installation positions and azimuth angles, establish a star sensor field of view cone angle model; 4) Based on the spatial coordinate transformation, discriminate the relationship between the sun point model and the field of view cone angle model, the relationship between the satellite point model and the field of view cone angle model, and output the effective field of view cone angle corresponding to the group of installation positions; 5) In the value space, give multiple sets of star sensor installation positions and azimuths in a discretized manner, return to step 3), use the next set of installation positions and azimuths to calculate again, and obtain each group of installation positions in the value space The effective FOV cone angle corresponding to the azimuth angle; 6) Compare all the effective cone angles of the field of view in the value space, and output the installation position and azimuth angle corresponding to the maximum effective cone angle of the field of view as the optimal layout position and azimuth angle. 2. a kind of star sensor automatic layout calculation method according to claim 1 is characterized in that: described step 1) utilizes ephemeris time to establish sun point model, and concrete steps are: given starting moment, time step length , the termination time as the input condition, according to the ephemeris, calculate the point coordinates of the sun in the J2000 coordinate system at N calculation times, convert the point coordinates to the star body coordinate system, and arrange the converted sun point coordinates in sequence to form the sun point Model A; N is a positive integer. 3. a kind of star sensor automatic layout calculation method according to claim 1, is characterized in that: described step 1) utilizes yellow and red angle to establish sun point model, and concrete steps are: given angle interval, equatorial plane The 360° circumference angle is discrete into m parts, and the angle between yellow and red is discrete into n parts of inclination angle, forming m × n groups of direction angles, each group of direction angles calculates a point coordinate of the sun position, and converts the point coordinate to the star body coordinate system , arrange the converted sun point coordinates to form the sun point model A; m and n are positive integers. 4. a kind of star sensor automatic layout calculation method according to claim 2 or 3, is characterized in that: the concrete steps of described step 2) are as follows: (2.1) Convert the CAD model of the satellite body and the antenna to the STL file represented in the star body coordinate system, read several triangular information matrices composed of point coordinates in the STL file; arrange all the triangular information matrices to form the satellite body , Antenna point model B; (2.2) By importing the CAD model STL file or manually setting, obtain the point coordinate information matrix of the vertex of the solar wing model in the star body coordinate system, and revolve each point in the point coordinate information matrix around the rotation axis of the solar wing to the set value Rotate 360 degrees at angular intervals to obtain several effective vertex information matrices of solar wings; arrange all effective vertex coordinate information matrices of solar wings to form a solar wing point model C; (2.3) By manually setting the coordinates of the points on the generatrix of each engine plume cone model, rotate each point 360 degrees around the engine plume jet axis at a set angle interval to obtain the effective boundary of the engine plume point, combine all the effective boundary point coordinate information to obtain the engine plume point model D; (2.4) Combine the satellite body, the point model B of the antenna, the point model C of the solar wing and the information matrix in the model D of the engine plume point to form the satellite point model E. 5. A kind of star sensor automatic layout calculation method according to claim 4, is characterized in that: in described step (2.1), given threshold σ, if the distance between certain two points in a certain triangle information matrix If it is greater than σ, insert several points on the connection line of the above two points, so that the distance between two adjacent points on the connection line is less than σ, and add the inserted points to the triangle information matrix to form a new triangle information matrix. 6. a kind of star sensor automatic layout calculation method according to claim 5 is characterized in that: the concrete steps of described step 3) are as follows: (3.1) In the value space, given any set of installation position reference points of the star sensor and the azimuth angle of the optical axis of the field of view, and calculate the three-coordinate axis vector of the field of view coordinate system of the star sensor in the star body coordinate system The coordinates in V _x , V _y , V _z ; (3.2) According to the three-axis vector coordinates, obtain the transformation matrix M from the star body coordinate system to the star sensor field of view coordinate system, M=[V _x , V _y , V _z ] ^T ; (3.3) According to the transformation matrix M and the origin of the field of view coordinate system of the star sensor, the transformation calculation of the point models A and E from the coordinate system of the star body to the coordinate system of the field of view of the star sensor is performed: R _l represents the coordinate information matrix of the lth point in point models A and E, is the coordinate information matrix of the lth point in the field of view coordinate system of the star sensor, O _ST is the coordinate information matrix of the origin of the field of view coordinate system; l is a positive integer. 7. a kind of star sensor automatic layout calculation method according to claim 6 is characterized in that: the concrete steps of described step 4) are as follows: (4.1) Calculation the angle ρ _l with the y-axis of the star sensor's field of view coordinate system; (4.2) Take the minimum value of the angle _ρj between all points in the point models A and E and the y-axis of the star sensor's field of view coordinate system, and denote it as It is the effective FOV cone angle corresponding to the current group installation position and azimuth angle.