CN110968910B - A dual-line-of-sight orthogonal lidar satellite attitude design method and control system - Google Patents

Abstract

A dual-sight orthogonal laser radar satellite attitude design method and a control system thereof have the advantages that the dual-sight orthogonal laser radar satellite measures a wind field, a plurality of radial velocity vectors are measured simultaneously, the uncertainty of wind speed caused by factors such as satellite flight speed, earth rotation speed and the like during data inversion is reduced, and the wind speed inversion precision of a satellite-borne wind-measuring laser radar system is effectively improved. Aiming at the application requirement that the laser radar satellite formation needs to form double-sight orthogonal observation, the invention provides a double-sight orthogonal laser radar satellite attitude calculation model, and then calculates the relative phase angle of the double-star formation by adopting an equation solving method, and calculates attitude parameters of the star. Under the condition that any attitude parameter of one satellite is known, the position and the attitude of the other satellite are solved, and basis is provided for formation and attitude design and control of the double-sight orthogonal laser radar satellite.

Description

A dual-line-of-sight orthogonal lidar satellite attitude design method and control system

Technical field

The invention relates to a dual-line-of-sight orthogonal laser radar satellite attitude design method and a control system, and in particular to a dual-line-of-sight orthogonal laser radar satellite formation attitude design method for space wind fields.

Background technique

When obtaining wind field information in a certain spatial area, the real-time intersection of 2 to 3 radial wind vectors in different directions is required. When using lidar to measure the atmospheric wind field, only one radial velocity component can be measured in one line of sight direction, so it is necessary to use multiple satellite formations to achieve multi-angle wind speed measurements. However, the formation of multiple satellites to achieve multi-angle wind speed measurement involves issues such as the simultaneity of multiple velocity vector data during data calculation, and the intersection of multi-vector real-time space in the same observation area. Currently, the existing technology has not seen the use of multi-satellite formations. A real-time measurement method for lidar spatial intersection.

In addition, when using lidar space intersection for measurement, it is necessary to select an appropriate intersection angle to meet the high-precision requirements for data interpretation; at the same time, it is also necessary to pay attention to satellite orbits, relative positions of different satellites, satellite line-of-sight directions, etc. The problem of mutual coupling of factors.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology, provide a dual-line-of-sight orthogonal laser radar satellite attitude design method and control system, and provide a dual-line of sight orthogonal laser radar satellite attitude calculation model, Then the equation solving method is used to calculate the relative phase angle of the binary star formation and solve the attitude parameters of the stars. It is possible to solve the position and attitude of another satellite when the attitude parameters of one satellite are known, which provides a basis for the laser radar satellite formation and attitude design of orthogonal dual line of sight.

The object of the present invention is achieved through the following technical solutions:

A dual-line-of-sight orthogonal lidar satellite attitude design method, using two lidar satellites satellite A and satellite B, includes the following steps:

S1. Establish a dual-line-of-sight orthogonal lidar satellite imaging model;

S2. Establish a right-hand coordinate system O-XYZ with the earth's center O as the origin, the earth's center O to satellite A as the Y axis, and the satellite A's flight speed direction as the X axis; according to the attitude angle of satellite A, calculate the distance from satellite A to the photography point D Vector in the O-XYZ coordinate system

S3. is the vector from satellite B to photography point D in the O-XYZ coordinate system, using the space vector/> Calculate the relative phase angle from satellite B to satellite A;

S4. Establish a right-hand coordinate system O-X'Y'Z' with the earth's center O as the origin, the earth's center O to satellite B as the Y axis, and the satellite B's flight speed direction as the X axis; use the coordinate transformation method to calculate the sum of S3 Using the relative phase angle mentioned above, calculate the coordinates of photography point D and satellite B in the O-X'Y'Z' coordinate system;

S5. Calculate the attitude parameters of satellite B based on the coordinates of photography point D and satellite B in the O-X'Y'Z' coordinate system.

Preferably, the satellite A and satellite B fly in formation within the same orbit.

Preferably, the attitude parameters of satellite B include the line-of-sight equivalent pitch angle θ _B of satellite B and the line-of-sight equivalent roll angle of satellite B. The equivalent pointing angle α _B of satellite B.

Preferably, in S3, the relative phase angle from satellite B to satellite A is calculated using the method of solving equations.

A dual-line-of-sight orthogonal lidar satellite attitude control system includes a dual-line of sight orthogonal lidar satellite imaging modeling module, a coordinate system module, and a data calculation module;

The dual-line-of-sight orthogonal lidar satellite imaging modeling module is used to establish a space model including satellite A, satellite B, photography point D, and earth center O;

The coordinate system module is used to establish a right-handed coordinate system O-XYZ with the earth's center O as the origin, the earth's center O to satellite A as the Y axis, and the satellite A's flight speed direction as the X axis; used to establish the earth's center O as the origin. , the right-hand coordinate system O-X'Y'Z' from the earth's center O to satellite B is the Y axis, and the satellite B's flight speed direction is the X axis;

The data calculation module is used to calculate the relative phase angle from satellite B to satellite A; used to calculate the coordinate transformation between the coordinate system O-XYZ and the coordinate system O-X'Y'Z'; used to calculate the attitude of satellite B parameter.

Preferably, the data calculation module first calculates the vector from satellite A to photography point D in the O-XYZ coordinate system based on the attitude angle of satellite A.

Then use the space vector Calculate the relative phase angle from satellite B to satellite A;/> is the vector from satellite B to photography point D in the O-XYZ coordinate system.

Preferably, the data calculation module uses the equation solving method to calculate the relative phase angle, uses the coordinate system transformation method to calculate the coordinates of the photography point D and satellite B in the O-X'Y'Z' coordinate system; and finally calculates the coordinates of satellite B Attitude parameters.

Preferably, the satellite A and satellite B fly in formation within the same orbit.

Preferably, the attitude parameters of satellite B include the line-of-sight equivalent pitch angle θ _B of satellite B and the line-of-sight equivalent roll angle of satellite B. The equivalent pointing angle α _B of satellite B.

Compared with the prior art, the present invention has the following beneficial effects:

(1) This shows that the equivalent line-of-sight pointing of lidar adopts a two-vector orthogonal method. The wind speed uncertainty caused by satellite flight speed, earth rotation speed and other factors during data inversion is small, which can effectively improve the spaceborne wind measurement laser. Radar system wind speed retrieval accuracy;

(2) On the basis of establishing the imaging model, the method of the present invention first uses the equation solving method to solve the relative phase angle of the satellite, and then further solves the attitude of the satellite. The method of solving equations avoids the complex calculation process caused by the use of spatial geometric transformation methods, and can also be well adapted to the situation where the measured object has elevation;

(3) The method of the present invention adopts a dual-line-of-sight orthogonal lidar satellite imaging model. Previous lidar satellites are all single-line-of-sight models and do not involve the solution problem of strict spatial intersection. Dual line of sight orthogonality allows lidar to measure two mutually orthogonal velocity vectors at the same photographic point, breaking through the traditional single-axis and one-dimensional velocity measurement method.

Description of the drawings

Figure 1 is a step flow chart of the method of the present invention;

Figure 2 is a schematic diagram of the lidar satellite attitude calculation model with orthogonal dual sight lines;

Figure 3 shows the attitude solution model of satellite B;

Figure 4 is a schematic diagram of the verification of dual line of sight orthogonality in STK;

Figure 5 shows the vector of satellite A’s lidar line of sight in the J2000 coordinate system;

Figure 6 shows the vector of satellite B lidar line of sight in the J2000 coordinate system.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

Example 1:

A dual-line-of-sight orthogonal laser radar satellite attitude design method uses two laser radar satellites, satellite A and satellite B. The satellite A and satellite B fly in formation within the same orbit, including the following steps:

S1. Establish a dual-line-of-sight orthogonal lidar satellite imaging model;

S2. Establish a right-hand coordinate system O-XYZ with the earth's center O as the origin, the earth's center O to satellite A as the Y axis, and the satellite A's flight speed direction as the X axis; according to the attitude angle of satellite A, calculate the distance from satellite A to the photography point D Vector in the O-XYZ coordinate system

S3. is the vector from satellite B to photography point D in the O-XYZ coordinate system, according to the space vector/> Use the method of solving equations to calculate the relative phase angle from satellite B to satellite A;

S4. Establish a right-hand coordinate system O-X'Y'Z' with the earth's center O as the origin, the earth's center O to satellite B as the Y axis, and the satellite B's flight speed direction as the X axis; use the coordinate transformation method to calculate the sum of S3 Using the relative phase angle mentioned above, calculate the coordinates of photography point D and satellite B in the O-X'Y'Z' coordinate system;

S5. Calculate the attitude parameters of satellite B based on the coordinates of photography point D and satellite B in the O-X'Y'Z' coordinate system. The attitude parameters of satellite B include the equivalent pitch angle θ _B of satellite B's line of sight, and the equivalent side roll angle of satellite B's line of sight. The equivalent pointing angle α _B of satellite B.

Example 2:

A dual-line-of-sight orthogonal lidar satellite attitude control system includes a dual-line of sight orthogonal lidar satellite imaging modeling module, a coordinate system module, and a data calculation module; the satellite A and satellite B fly in formation within the same orbit.

The dual-line-of-sight orthogonal lidar satellite imaging modeling module is used to establish a space model including satellite A, satellite B, photography point D, and earth center O;

The coordinate system module is used to establish a right-handed coordinate system O-XYZ with the earth's center O as the origin, the earth's center O to satellite A as the Y axis, and the satellite A's flight speed direction as the X axis; used to establish the earth's center O as the origin. , the right-hand coordinate system O-X'Y'Z' from the earth's center O to satellite B is the Y axis, and the satellite B's flight speed direction is the X axis;

The data calculation module is used to calculate the relative phase angle from satellite B to satellite A; used to calculate the coordinate transformation between the coordinate system O-XYZ and the coordinate system O-X'Y'Z'; used to calculate the attitude of satellite B parameter.

Specifically, the data calculation module first calculates the vector from satellite A to photography point D in the O-XYZ coordinate system based on the attitude angle of satellite A. Then use the space vector/> Calculate the relative phase angle from satellite B to satellite A; is the vector from satellite B to photography point D in the O-XYZ coordinate system. The data calculation module uses the equation solving method to calculate the relative phase angle, uses the coordinate system transformation method to calculate the coordinates of the photography point D and satellite B in the O-X'Y'Z' coordinate system; and finally calculates the attitude parameters of satellite B. The attitude parameters of satellite B include the equivalent pitch angle θ _B of satellite B's line of sight, and the equivalent side roll angle of satellite B's line of sight/> The equivalent pointing angle α _B of satellite B.

Example 3:

Figure 1 shows a flow chart of the method in this embodiment. The method of this embodiment is aimed at the application requirements of the LiDAR satellite formation that requires orthogonal observations with dual line of sight. Based on the establishment of a LiDAR satellite attitude calculation model with orthogonal dual line of sight, the relative phase angle of the double-satellite formation is obtained by solving equations. , and further solved to obtain the attitude parameters of the satellite. This method realizes the solution to obtain the position and attitude of the other satellite when the attitude parameters of one satellite are known, providing a basis for the laser radar satellite formation and attitude design of orthogonal dual line of sight.

① Satellite attitude model with orthogonal dual line of sight

Satellite A and satellite B are a double-star formation constellation operating in the same orbital plane. Along the flight direction in the orbital plane, the geocentric angle of satellite A is ζ angle later than that of satellite B, as shown in Figure 2. Satellite A has a pitch angle θ and a roll angle Point to laser photography point D, the lower point of satellite A is A'; satellite B is at pitch angle θ _B and side swing angle/> Point to the laser photography point D, and the point below star B is B'. At given parameters θ and/> When , there exists a set of ζ, θ _B and /> Make/>

② Calculation of A-star line of sight pointing parameters

View from star A:

The angle between the plane AOD and the track plane

The distance from satellite A to target point D is:

Among them, the semi-major axis of the satellite orbit is Rs, and the distance from the earth's center O to the target point D is Re.

Establish a spatial coordinate system O-XYZ with point O as the origin, OA as the Y-axis, the X-axis along the satellite speed direction, and the Z-axis perpendicular to the paper surface. The coordinates of several points related to star A are:

③ Calculation of B star position parameters

Satellites A and B are both running in the same orbit, and the coordinates of point B can be assumed to be Therefore the vector BD can be expressed as:

space vector Yes/> Right now

Solving this equation, we get

In the function x(L,α,Rs,η,Re), the orbital spacing x is a positive value, so there is

Rs is the satellite orbit height, and Re is the distance between the photography point and the center of the earth. Substituting formulas (1) and (2) into them, the numerical solution of x can be obtained. The geocentric angle ζ corresponding to satellite A and satellite B:

④Calculation of attitude parameters of B star

Establish a new coordinate system O-X'Y'Z' with OB as the Y-axis, that is, the original coordinate system O-XYZ rotates counterclockwise around the Z-axis by an angle ζ. As shown in Figure 3, the equivalent pitch angle θ _B of the satellite line of sight, the equivalent side swing angle of the satellite line of sight The lower viewing angle is the composite α _B of the two angles. The coordinates of intersection point D and the new coordinates of satellite B in the new coordinate system:

(11)

The distance L _B from satellite B to photography point D:

Satellite line-of-sight equivalent pitch angle θ _B :

Satellite line of sight equivalent side angle

Equivalent pointing angle α _B :

Application effect of Example 3:

Taking the lidar satellite operating in a sun-synchronous return orbit with a semi-major axis of 6774.64km as an example, the side swing angle of Star A is 35° and the pitch angle is 45°. The calculation shows that x = 978.3748km, the geocentric angle difference ζ between Star A and Star B = 8.3035°, and further calculations show that the pitch angle θ _B = -38.3173° and side swing angle of Star B Set the attitude angles of star A and star B in the STK software. As shown in Figure 4, the lidar fields of view can completely overlap. Output the pointing vectors of satellite A and B satellite lidars. The results are shown in Figure 5 and Figure 6 respectively. The dot multiplication of the two vectors is 0, that is, the two pointing vectors are vertical, which meets the requirements for orthogonal observation of lidar dual line of sight.

Contents not described in detail in the specification of the present invention are well-known technologies to those skilled in the art.

Although the present invention has been disclosed above in terms of preferred embodiments, they are not intended to limit the present invention. Any person skilled in the art can utilize the methods and technical contents disclosed above to improve the present invention without departing from the spirit and scope of the present invention. Possible changes and modifications are made to the technical solution. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention, all belong to the technical solution of the present invention. protected range.

Claims (4)

1. A dual-line-of-sight orthogonal lidar satellite attitude design method, using two lidar satellites satellite A and satellite B, is characterized by including the following steps: S1. Establish a dual-line-of-sight orthogonal lidar satellite imaging model; S2. Establish a right-hand coordinate system O-XYZ with the earth's center O as the origin, the earth's center O to satellite A as the Y axis, and the satellite A's flight speed direction as the X axis; according to the attitude angle of satellite A, calculate the distance from satellite A to the photography point D Vector in the O-XYZ coordinate system S3. is the vector from satellite B to photography point D in the O-XYZ coordinate system, using the space vector/> Calculate the relative phase angle from satellite B to satellite A, specifically the geocentric angle ζ corresponding to satellite A and satellite B: x is the orbital spacing, Rs is the satellite orbital height; S4. Establish a right-hand coordinate system O-X'Y'Z' with the earth's center O as the origin, the earth's center O to satellite B as the Y axis, and the satellite B's flight speed direction as the X axis; use the coordinate transformation method to calculate the sum of S3 Using the relative phase angle mentioned above, calculate the coordinates of photography point D and satellite B in the O-X'Y'Z' coordinate system, specifically as follows: L is the distance from satellite A to photographing point D, α is the viewing angle under satellite A, eta is the angle between plane AOD and the orbital plane, D'('x _D ', y _D ', z _D ') is the angle of photographing point D Coordinates, B'('x _B ', y _B ', z _B ') are the coordinates of satellite B; S5. Calculate the attitude parameters of satellite B based on the coordinates of photography point D and satellite B in the O-X'Y'Z' coordinate system, including: Satellite line-of-sight equivalent pitch angle θ _B : Satellite line of sight equivalent side angle Equivalent pointing angle α _B : Re is the distance from the center of the earth O to the target point D. 2. A method for designing the attitude of a laser radar satellite with orthogonal dual sight lines according to claim 1, characterized in that the satellite A and the satellite B fly in formation within the same orbit. 3. A method for designing the attitude of a laser radar satellite with orthogonal dual sight lines according to claim 1 or 2, characterized in that, in S3, the relative phase angle from satellite B to satellite A is calculated using the method of solving equations. 4. A dual-line-of-sight orthogonal lidar satellite attitude control system, characterized by including a dual-line of sight orthogonal lidar satellite imaging modeling module, a coordinate system module, and a data calculation module; The dual-line-of-sight orthogonal lidar satellite imaging modeling module is used to establish a space model including satellite A, satellite B, photography point D, and earth center O; The coordinate system module is used to establish a right-handed coordinate system O-XYZ with the earth's center O as the origin, the earth's center O to satellite A as the Y axis, and the satellite A's flight speed direction as the X axis; used to establish the earth's center O as the origin. , the right-hand coordinate system O-X'Y'Z' from the earth's center O to satellite B is the Y axis, and the satellite B's flight speed direction is the X axis; The data calculation module is used to calculate the relative phase angle from satellite B to satellite A, specifically the geocentric angle ζ corresponding to satellite A and satellite B: x is the orbital spacing, Rs is the satellite orbital height; The data calculation module is also used to calculate the coordinate transformation between the coordinate system O-XYZ and the coordinate system O-X'Y'Z', specifically: L is the distance from satellite A to photographing point D, α is the viewing angle under satellite A, eta is the angle between plane AOD and the orbital plane, D'('x _D ', y _D ', z _D ') is the angle of photographing point D Coordinates, B'('x _B ', y _B ', z _B ') are the coordinates of satellite B; The data calculation module is also used to calculate the attitude parameters of satellite B, including: Satellite line-of-sight equivalent pitch angle θ _B : Satellite line of sight equivalent side angle Equivalent pointing angle α _B : Re is the distance from the center of the earth O to the target point D.