On-orbit real-time target positioning method and device

Abstract

The invention provides an in-orbit real-time target positioning method and equipment. The method comprises the following steps: acquiring an orbit position coordinate at a satellite imaging moment; establishing an external calibration parameter model and a resection geometric imaging model of area-array camera observation to the sky, and obtaining a corrected camera mounting angle and a corrected rotation matrix from a satellite body coordinate system to a camera coordinate system; establishing an internal calibration parameter model and an adjustment model of the directional angle of the area array probe element of the detector, and obtaining a corrected directional angle of the camera; obtaining a corrected attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the imaging moment; the updated pitch angle and the updated side-sway angle of the imaging optics in the satellite orbit coordinate system are obtained; establishing a forward intersection geometric imaging model for earth observation of the area array optical satellite; and obtaining position coordinates of the target point. The technical problems that in the prior art, a positioning method is low in precision and cannot meet the requirement for quick response to a high-dynamic real-time positioning task can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of target positioning, and in particular, to an on-orbit real-time target positioning method and device. Background Art

[0002] With the continuous improvement of the resolution of remote sensing imaging satellites and the on-board computing resources, higher requirements have been put forward for the accuracy and timeliness of satellite image processing in various industries. The factors affecting the geometric positioning accuracy of optical imaging mainly include satellite orbit determination accuracy, satellite attitude determination accuracy, and optical camera calibration accuracy. Traditional processing methods send the satellite's orbit, attitude, and image data to the ground first, obtain the orbit data through post-precision orbit determination, use star sensors and gyroscopes to jointly determine the attitude information, calibrate the internal and external parameters of the optical camera based on ground reference images, and compensate for various systematic errors in the satellite imaging process. High-precision geometric positioning can be achieved through the above series of data processing.

[0003] According to the working mode, remote sensing satellites are divided into two types: static push-broom satellites and staring imaging satellites. When a static push-broom satellite observes the ground, it has a large swath width, high resolution, stable satellite attitude, high attitude determination accuracy, and high target positioning accuracy. However, its real-time performance is poor, and it only has the ability to perform single imaging reconnaissance on target points. When a staring imaging satellite observes the ground, it has a small swath width and high resolution. Through attitude maneuvering, it can achieve continuous observation of a target area for a period of time. During the attitude maneuvering process, the attitude determination accuracy drops severely, which seriously restricts the real-time positioning accuracy. In addition, due to the long delay from data acquisition to data downlink processing of various relevant data on the satellite, the timeliness is poor, and it cannot meet the requirements of fast-response high-dynamic real-time positioning tasks. Summary of the Invention

[0004] The present invention provides an on-orbit real-time target positioning method and device, which can solve the technical problems in the prior art that the positioning method has low accuracy and cannot meet the requirements of fast-response high-dynamic real-time positioning tasks.

[0005] According to one aspect of the present invention, an on-orbit real-time target positioning method is provided, and the method includes:

[0006] Obtain the orbital position coordinates at the satellite imaging moment;

[0007] Establish an external calibration parameter model and a resection geometric imaging model of the area array camera observing the sky, and obtain the corrected camera mounting angle and the rotation matrix from the corrected satellite body coordinate system to the camera coordinate system based on the external calibration parameter model and the resection geometric imaging model;

[0008] Establish an internal calibration parameter model and an adjustment model for the detector area array element pointing angle, and obtain the corrected camera pointing angle based on the internal calibration parameter model and the adjustment model;

[0009] Based on the attitude determination algorithm combining star sensors and gyroscopes, determine the attitude quaternion of the satellite body coordinate system relative to the J2000 inertial coordinate system, and obtain the attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the corrected imaging time based on the attitude quaternion;

[0010] Based on the corrected camera pointing angle and the actual side viewing angle during the optical camera's observation of the ground, obtain the updated pitch angle and roll angle of the imaging optics in the satellite orbital coordinate system;

[0011] Based on the orbital position coordinates at the satellite imaging time, the corrected camera mounting angle, the corrected rotation matrix from the satellite body coordinate system to the camera coordinate system, the corrected attitude rotation matrix from the body coordinate system to the J2000 inertial coordinate system at the imaging time, and the updated pitch angle and roll angle of the imaging optics in the satellite orbital coordinate system, establish a forward intersection geometric imaging model for the area array optical satellite's observation of the ground;

[0012] Based on the forward intersection geometric imaging model for the area array optical satellite's observation of the ground and the ellipsoid equation, obtain the position coordinates of the target point.

[0013] Preferably, obtaining the orbital position coordinates at the satellite imaging time includes:

[0014] The on-board receiver obtains observation data in real time;

[0015] Use Kalman filtering to eliminate the pseudo-range gross error in the observation data, and obtain the observation data after eliminating the pseudo-range gross error;

[0016] Based on the observation data after eliminating the pseudo-range gross error, use geometric orbit to obtain the real-time single-point positioning and speed determination information of the satellite;

[0017] Perform extended Kalman filtering on the real-time single-point positioning and speed determination information of the satellite to estimate the state parameters of the satellite;

[0018] Perform Hermite polynomial interpolation on the state parameters of the satellite to obtain the orbital position coordinates at the satellite imaging time.

[0019] Preferably, establishing an external calibration parameter model and a back-projection geometric imaging model for the area array camera's observation of the sky, and obtaining the corrected camera mounting angle based on the external calibration parameter model and the back-projection geometric imaging model includes:

[0020] Obtain star map data;

[0021] With the assistance of the navigation star catalog, extract the right ascension and declination of the stars from the star map data;

[0022] Based on the right ascension and declination of the stars and the camera mounting angle, establish an external calibration parameter model;

[0023] Obtain the stellar observation vector based on the right ascension and declination of the star;

[0024] Establish a resection geometric imaging model for the sky observation of the area array camera based on the collinear relationship between the stellar observation vector and the line-of-sight pointing vector of the satellite payload;

[0025] Establish the first adjustment equation and the first error equation based on the external calibration parameter model and the resection geometric imaging model, and use the least squares adjustment method to iteratively solve the first adjustment equation and the first error equation until the external calibration parameters converge. Correct the camera mounting angle based on the converged external calibration parameters to obtain the corrected camera mounting angle;

[0026] Obtain the rotation matrix from the corrected satellite body coordinate system to the camera coordinate system based on the corrected camera mounting angle.

[0027] Preferably, establish the resection geometric imaging model for the sky observation of the area array camera through the following formula:

[0028]

[0029] Establish the first adjustment equation through the following formula:

[0030]

[0031]

[0032] where,

[0033] Establish the first error equation through the following formula:

[0034]

[0035] where,

[0036] Obtain the corrected camera mounting angle through the following formula:

[0037] α′ = α + dα

[0038] β′ = β + dβ

[0039] γ′ = γ + dγ

[0040] In the formula, are the pitch angle and the roll angle respectively, μ is the scaling coefficient, is the rotation matrix from the satellite body coordinate system to the camera coordinate system, (α, β, γ) is the mounting angle of the optical camera on the satellite body, and α, β, γ are the azimuth angle, pitch angle, and yaw angle of the optical camera on the satellite body respectively, is the rotation matrix from the J2000 inertial coordinate system to the satellite body coordinate system, and (r, p, y) are the attitude angles of the satellite body relative to the J2000 inertial coordinate system. r, p, and y are the roll angle, pitch angle, and yaw angle of the satellite body relative to the J2000 inertial coordinate system, respectively. R Aber is the light travel time correction matrix, and α0 and δ0 are the right ascension and declination, respectively. G x and G y are the vector residual functions of the image point along the track and perpendicular to the track directions in the image space coordinate system, respectively. is the vector of the observed star in the X, Y, and Z directions in the camera coordinate system. is the error value of the i-th star control point in the star camera coordinate system. A i is the coefficient matrix of the error equation of the star control point. L i is the constant vector of the error equation of the star control point. x = [dα, dβ, dγ] T is the correction vector of the three external calibration parameters. α′, β′, and γ′ are the azimuth angle, pitch angle, and yaw angle of the optical camera after calibration in the satellite body, respectively.

[0041] Preferably, establish the internal calibration parameter model and adjustment model of the detector array element pointing angle, and obtain the corrected camera pointing angle based on the internal calibration parameter model and adjustment model, including:

[0042] Establish the internal calibration parameter model of the detector array element pointing angle;

[0043] Obtain overlapping ground images through attitude maneuvers, obtain point matching based on the overlapping ground images, obtain the position coordinates of the ground points in the WGS84 coordinate system based on the point matching, and establish an adjustment model based on the point matching, the position coordinates of the ground points in the WGS84 coordinate system, and the resection geometric imaging model;

[0044] Based on the internal calibration parameter model and adjustment model, establish the second adjustment equation and the second error equation, and use the least squares adjustment method to iteratively solve the second adjustment equation and the second error equation until the internal calibration parameters converge. Based on the converged internal calibration parameters, correct the camera pointing angle to obtain the corrected camera pointing angle.

[0045] Preferably, establish the internal calibration parameter model of the detector array element pointing angle through the following formula:

[0046]

[0047]

[0048] Establish the adjustment model through the following formula:

[0049]

[0050] The second adjustment equation is established by the following formula:

[0051]

[0052]

[0053] The second error equation is established by the following formula:

[0054]

[0055]

[0056] Wherein, s and l are respectively the row and column of the CMOS detector number, and (a0,... a9, b0,... b9) are the internal calibration parameters of the on-orbit geometry, are the X, Y, and Z direction vectors of the ground overlapping image points in the camera coordinate system, is the rotation matrix from the WGS84 coordinate system to the J2000 inertial coordinate system, X g , Y g , Z g are respectively the X, Y, and Z direction position coordinates of the ground points in the WGS84 coordinate system, X gps , Y gps , Z gps are respectively the X, Y, and Z direction orbital position coordinates of the satellite imaging time in the WGS84 coordinate system, F x , F y are respectively the vector residual functions of the image points along the track and perpendicular to the track in the image space coordinate system, and are respectively the correction vector corresponding to the image points on the left and right images, y = [da1,... da9, db1,... db9] T is the correction vector of the camera internal calibration parameters, and are respectively the partial derivative coefficient matrices corresponding to the calibration parameters in the left and right image point error equations, and are respectively the partial derivative coefficient matrices corresponding to the object space coordinates in the left and right image point error equations, and are respectively the constant vectors in the left and right image point error equations, represents the object space plane coordinate correction vector of each homologous image point.

[0057] Preferably, the attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the corrected imaging time is obtained by the following formula:

[0058]

[0059]

[0060] In the formula, is the attitude rotation matrix from the body coordinate system to the J2000 inertial coordinate system at the corrected imaging time, is the attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the corrected imaging time, and q = [q0 q1 q2 q3] T is the attitude quaternion, and q0, q1, q2, and q3 are the first, second, third, and fourth elements of the attitude quaternion, respectively.

[0061] Preferably, the updated pitch angle of the imaging optics in the satellite orbit coordinate system is obtained by the following formula:

[0062]

[0063] The updated yaw angle of the imaging optics in the satellite orbit coordinate system is obtained by the following formula:

[0064]

[0065] Wherein,

[0066] In the formula, are the updated pitch angle and yaw angle, respectively, are the corrected pitch angle and yaw angle, respectively, χ is the actual side view angle, χ0 is the original side view angle, R is the satellite altitude, H is the satellite orbit radius, and δθ is the line-of-sight angle deviation of the optical remote sensing satellite for earth observation.

[0067] Preferably, the forward intersection geometric imaging model of the area array optical satellite for earth observation is established by the following formula:

[0068]

[0069] The ellipsoid equation is established by the following formula:

[0070]

[0071] In the formula, X, Y, and Z are the position coordinates of the target point in the X, Y, and Z directions, a and b are the semi-major axis and semi-minor axis of the WGS84 reference ellipsoid, respectively, and h is the height of the ground target point corresponding to the image point from the reference ellipsoid surface.

[0072] According to another aspect of the present invention, a computer device is provided, including a memory, a processor, and an on-orbit real-time target positioning program stored on the memory and executable on the processor. When the processor executes the on-orbit real-time target positioning program, the above-mentioned any method is implemented.

[0073] Applying the technical solution of the present invention, to achieve high-precision on-orbit real-time target positioning under high dynamic conditions, in addition to relying on an on-board high-performance computing platform, orbit determination, attitude determination, and calibration algorithms adapted to on-orbit real-time positioning on the satellite, as well as a line-of-sight angle dynamic compensation algorithm during the imaging process are also considered. The present invention solves the problem that existing aircraft such as satellites equipped with single monocular optical payloads cannot perform high-precision real-time positioning of dynamic targets through a single optical image. Description of the Drawings

[0074] The accompanying drawings included are used to provide a further understanding of the embodiments of the present invention, which form a part of the specification, are used to illustrate the embodiments of the present invention, and together with the written description are used to explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0075] Figure 1 The flowchart of the on-orbit real-time target positioning method provided according to an embodiment of the present invention is shown. Detailed Embodiments

[0076] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0077] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0078] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0079] As Figure 1 shown, the present invention provides a method for on-orbit real-time target positioning, the method comprising:

[0080] S10. Obtain the orbital position coordinates at the satellite imaging moment;

[0081] S20. Establish an external calibration parameter model and a resection geometric imaging model for the area array camera's observation of the sky, and obtain the corrected camera mounting angle and the rotation matrix from the corrected satellite body coordinate system to the camera coordinate system based on the external calibration parameter model and the resection geometric imaging model;

[0082] S30. Establish an internal calibration parameter model for the detector area array element pointing angle and an adjustment model, and obtain the corrected camera pointing angle based on the internal calibration parameter model and the adjustment model;

[0083] S40. Determine the attitude quaternion of the satellite body coordinate system relative to the J2000 inertial coordinate system based on the star sensor and gyro combined attitude determination algorithm, and obtain the attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the corrected imaging moment based on the attitude quaternion;

[0084] S50. Obtain the updated pitch angle and yaw angle of the imaging optics in the satellite orbit coordinate system based on the corrected camera pointing angle and the actual side viewing angle when the optical camera observes the ground;

[0085] S60. Establish a resection geometric imaging model for the area array optical satellite's observation of the ground based on the orbital position coordinates at the satellite imaging moment, the corrected camera mounting angle, the rotation matrix from the corrected satellite body coordinate system to the camera coordinate system, the attitude rotation matrix from the corrected body coordinate system to the J2000 inertial coordinate system at the imaging moment, and the updated pitch angle and yaw angle of the imaging optics in the satellite orbit coordinate system;

[0086] S70. Obtain the position coordinates of the target point based on the forward intersection geometric imaging model of the area array optical satellite for earth observation and the ellipsoid equation.

[0087] The present invention realizes on-orbit high-precision real-time target positioning under high dynamic conditions. In addition to relying on the on-board high-performance computing platform, it also considers the orbit determination, attitude determination, and calibration algorithms suitable for on-orbit real-time positioning, as well as the line-of-sight angle dynamic compensation algorithm during the imaging process. The present invention solves the problem that existing aircraft such as satellites equipped with single optical payloads cannot perform high-precision real-time positioning of dynamic targets through single optical images.

[0088] According to an embodiment of the present invention, in S10 of the present invention, autonomous real-time orbit determination is performed based on GNSS. Autonomous real-time orbit determination based on GNSS is a prerequisite for high-precision on-orbit real-time target positioning and is used to obtain the orbital position information of the satellite at the imaging moment. The present invention adopts dynamic autonomous real-time orbit determination based on GNSS pseudorange and Doppler measurements.

[0089] Specifically, obtaining the orbital position coordinates of the satellite at the imaging moment includes:

[0090] The on-board receiver obtains observation data in real time; among them, the observation data includes satellite ephemeris, pseudorange, Doppler, etc.;

[0091] Use Kalman filtering to eliminate the pseudorange gross error in the observation data to obtain the observation data after eliminating the pseudorange gross error;

[0092] Based on the observation data after eliminating the pseudorange gross error, use geometric orbit to obtain the real-time single-point positioning and speed determination information of the satellite;

[0093] Perform extended Kalman filtering on the real-time single-point positioning and speed determination information of the satellite to estimate the state parameters of the satellite;

[0094] Perform Hermite polynomial interpolation on the state parameters of the satellite to obtain the orbital position coordinates of the satellite at the imaging moment.

[0095] According to an embodiment of the present invention, in S20 and S30 of the present invention, on-orbit autonomous geometric calibration is used. High-precision attitude determination is a prerequisite for high-precision on-orbit real-time target positioning and is used for external calibration of the installation angle parameters of the optical camera and internal calibration of the pointing angle parameters of the area array detector elements.

[0096] Specifically, the present invention adopts the method of autonomous external calibration based on star observation to avoid relying on the ground high-precision control field and reference images. Among them, establishing an external calibration parameter model and a rear intersection geometric imaging model of the area array camera for sky observation, and obtaining the corrected camera installation angle based on the external calibration parameter model and the rear intersection geometric imaging model includes:

[0097] Utilize the agile maneuvering ability of the satellite to photograph suitable celestial regions and obtain stellar chart data;

[0098] With the assistance of the navigation star catalog, extract the right ascension and declination of the stars from the stellar chart data; these are the externally calibrated observed values of the right ascension and declination;

[0099] Based on the right ascension and declination of the stars and the camera mounting angle, establish an externally calibrated parameter model;

[0100] Based on the right ascension and declination of the stars, obtain the stellar observation vector (cosα0cosδ0, sinα0cosδ0, sinδ0) T ;

[0101] Based on the collinearity relationship between the stellar observation vector and the line-of-sight pointing vector of the satellite payload establish a resection geometric imaging model for the area array camera's observation of the sky;

[0102] Based on the externally calibrated parameter model and the resection geometric imaging model, establish the first adjustment equation and the first error equation, and use the least squares adjustment method to iteratively solve the first adjustment equation and the first error equation until the externally calibrated parameters converge. Based on the converged externally calibrated parameters, correct the camera mounting angle to obtain the corrected camera mounting angle;

[0103] Based on the corrected camera mounting angle, obtain the rotation matrix from the corrected satellite body coordinate system to the camera coordinate system

[0104] Furthermore, establish a resection geometric imaging model for the area array camera's observation of the sky through the following formula:

[0105]

[0106] Establish the first adjustment equation through the following formula:

[0107]

[0108]

[0109] where,

[0110] Establish the first error equation through the following formula:

[0111]

[0112] where,

[0113] Obtain the corrected camera mounting angle through the following formula:

[0114] α′ = α + dα

[0115] β′ = β + dβ

[0116] γ′ = γ + dγ

[0117] Wherein, are the pitch angle and yaw angle respectively, μ is the scaling factor, is the rotation matrix from the satellite body coordinate system to the camera coordinate system, (α, β, γ) is the installation angle of the optical camera on the satellite body, and α, β, γ are the azimuth angle, pitch angle, and yaw angle of the optical camera on the satellite body respectively, is the rotation matrix from the J2000 inertial coordinate system to the satellite body coordinate system, (r, p, y) is the attitude angle of the satellite body relative to the J2000 inertial coordinate system, and r, p, y are the roll angle, pitch angle, and yaw angle of the satellite body relative to the J2000 inertial coordinate system respectively, R Aber is the aberration correction matrix, α0 and δ0 are the right ascension and declination respectively, G x and G y are the vector residual functions of the image point along the track and perpendicular to the track directions in the image space coordinate system respectively, is the vector of the observed star in the X, Y, and Z directions in the camera coordinate system, is the error value of the i-th star control point in the star camera coordinate system, A i is the coefficient matrix of the error equation of the star control point, L i is the constant vector of the error equation of the star control point, x = [dα, dβ, dγ] T is the correction vector of the three external calibration parameters, and α′, β′, γ′ are the azimuth angle, pitch angle, and yaw angle of the optical camera on the satellite body after calibration respectively.

[0118] Specifically, the present invention adopts the method of autonomous internal calibration based on the overlapping images of imaging the ground. Among them, establishing the internal calibration parameter model and adjustment model of the detector array element pointing angle, and obtaining the corrected camera pointing angle based on the internal calibration parameter model and adjustment model includes:

[0119] Establish the internal calibration parameter model of the detector array element pointing angle;

[0120] Obtain the overlapping ground images through attitude maneuver, obtain the point matching based on the overlapping ground images, obtain the position coordinates of the ground points in the WGS84 coordinate system based on the point matching, and establish the adjustment model based on the point matching, the position coordinates of the ground points in the WGS84 coordinate system, and the geometric imaging model of resection;

[0121] Based on the pre - calibration parameter model and the adjustment model, establish the second adjustment equation and the second error equation, and use the least - squares adjustment method to iteratively solve the second adjustment equation and the second error equation until the pre - calibration parameters converge. Then, correct the camera pointing angle based on the converged pre - calibration parameters to obtain the corrected camera pointing angle

[0122] Furthermore, establish the pre - calibration parameter model of the detector array element pointing angle through the following formula:

[0123]

[0124]

[0125] Establish the adjustment model through the following formula:

[0126]

[0127] Establish the second adjustment equation through the following formula:

[0128]

[0129]

[0130] Establish the second error equation through the following formula:

[0131]

[0132]

[0133] In the formula, s and l are the row and column of the CMOS element number respectively, and (a0, … a9, b0, … b9) are the pre - calibration parameters of the on - orbit geometry are the X, Y, and Z direction vectors of the ground overlapping image points in the camera coordinate system is the rotation matrix from the WGS84 coordinate system to the J2000 inertial coordinate system, X g , Y g , Z g are the X, Y, and Z direction position coordinates of the ground points in the WGS84 coordinate system respectively, X gps , Y gps , Z gps are the X, Y, and Z direction orbital position coordinates of the satellite imaging time in the WGS84 coordinate system respectively, F x , F y are the vector residual functions of the image points along and perpendicular to the track directions in the image space coordinate system respectively and are the correction vector corresponding to the image points on the left and right images respectively, y = [da1, … da9, db1, … db9] Tis the correction vector of the camera's internal calibration parameters, and are the partial derivative coefficient matrices corresponding to the calibration parameters in the left and right image point error equations respectively, and are the partial derivative coefficient matrices corresponding to the object space coordinates in the left and right image point error equations respectively, and are the constant vectors in the left and right image point error equations respectively, represents the correction vector of the object space plane coordinates of each homologous image point.

[0134] According to an embodiment of the present invention, in S40 of the present invention, star sensor and gyroscope combined attitude determination is performed. High-precision attitude determination is a prerequisite for high-precision on-orbit real-time target positioning. To meet the high-precision and high-stability attitude determination requirements of the satellite platform, a star sensor and gyroscope combined attitude determination method is adopted.

[0135] When the traditional star sensor operates statically and stably, it has high measurement accuracy. When the satellite platform adjusts its attitude at a large angular velocity, relative motion is generated between the star sensor and the stars, resulting in star trailing on the star sensor image plane during the exposure time. The starlight energy is dispersed and distributed to the pixels around the trajectory, and the measurement accuracy of the star point decreases, even leading to attitude determination failure. The gyroscope has a drift problem, and the error accumulates over time and continuously increases. It cannot be used independently for a long time, but can provide continuous angular velocity measurement information.

[0136] For the attitude maneuver process of the geosynchronous observation satellite's staring imaging, before the attitude maneuver process, the gyro drift parameters are corrected based on the measurement information of the star sensor. When the satellite maneuvers its attitude, the gyro measurement results are used as the basis, and the extended Kalman filter algorithm is used to filter the gyro measurement results and the star sensor measurement information. On the one hand, it can ensure the high accuracy and continuity of the attitude information, and on the other hand, it can estimate parameters such as the drift of the gyroscope using the filtering algorithm.

[0137] Specifically, the attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the corrected imaging time is obtained through the following formula:

[0138]

[0139]

[0140] In the formula, is the attitude rotation matrix from the body coordinate system to the J2000 inertial coordinate system at the corrected imaging time, is the attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the corrected imaging time, q = [q0 q1 q2 q3] Tis the attitude quaternion, and q0, q1, q2, and q3 are the first, second, third, and fourth elements of the attitude quaternion, respectively.

[0141] According to an embodiment of the present invention, in S50 of the present invention, high-precision in-orbit compensation of the line-of-sight angle for earth observation is performed. When the incident light passes through the non-uniform density atmosphere, a line-of-sight angle deviation is generated. To ensure the in-orbit real-time target positioning accuracy, the atmosphere is adaptively stratified into altitude layers according to the variation parameter of the atmospheric refraction index, and the incident angle and refraction angle of each altitude layer are calculated by using the ray tracing method. The line-of-sight angle deviation δθ of the optical remote sensing satellite for earth observation is calculated by using geometric relations.

[0142] When the atmospheric refraction error is corrected, the actual side view angle during the earth observation by the optical camera is χ.

[0143]

[0144] The updated pitch angle of the imaging optics in the satellite orbital coordinate system is obtained by the following formula:

[0145]

[0146] The updated roll angle of the imaging optics in the satellite orbital coordinate system is obtained by the following formula:

[0147]

[0148] In the formula, are the updated pitch angle and roll angle, respectively, are the corrected pitch angle and roll angle, respectively, χ is the actual side view angle, χ0 is the original side view angle, R is the satellite altitude, H is the satellite orbital radius, and δθ is the line-of-sight angle deviation of the optical remote sensing satellite for earth observation.

[0149] According to an embodiment of the present invention, in S60 of the present invention, a surface array optical satellite target positioning model is performed. Based on the imaging time of the optical image, the attitude and orbit data of the satellite are interpolated to obtain the attitude and orbit parameters at the imaging time. Then, based on the geometric relationship that the image point, object point, and projection center are collinear, a forward intersection geometric imaging model for the surface array optical satellite to observe the earth is established, as shown in the following formula:

[0150]

[0151] The above formula can be rewritten as:

[0152] X = X gps + mu x

[0153] Y = Y gps + mu y

[0154] Z=Z gps +mu z

[0155] In S70 of the present invention, the ellipsoidal surface equation is established by the following formula:

[0156]

[0157] Where X, Y, and Z are the X, Y, and Z coordinates of the target point, a and b are the major and minor axes of the WGS84 reference ellipsoid, respectively. a = 6378137 m, b = 6356752.3 m, h is the height of the ground target point corresponding to the image point from the reference ellipsoid, and m is the scale factor. (u x ,u y ,u z ) is the direction vector from the target to the satellite.

[0158] With the support of digital elevation data DEM, the height h is known, and the rewritten forward intersection geometric imaging model and the ellipsoidal surface equation are combined to obtain:

[0159]

[0160] Solve the scale factor m and iterate multiple times, then bring the obtained m into the rewritten forward intersection geometric imaging model to solve the position coordinates (X, Y, Z) of the target point.

[0161] The present invention also provides a computer device, comprising a memory, a processor, and an on-orbit real-time target positioning program stored in the memory and executable on the processor, wherein the processor implements any of the above-mentioned methods when executing the on-orbit real-time target positioning program.

[0162] In summary, the present invention provides a method and device for real-time on-orbit target positioning. The method is to achieve high-precision real-time on-orbit target positioning on a satellite under high dynamic conditions. In addition to relying on a satellite-borne high-performance computing platform, it also considers orbit determination, attitude determination and calibration algorithms adapted to real-time on-orbit positioning on a satellite, as well as a dynamic supplement algorithm for the line of sight during the imaging process. The present invention solves the problem that existing satellites and other aircraft equipped with monocular optical payloads cannot perform high-precision real-time positioning of dynamic targets through a single optical image.

[0163] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0164] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. is usually based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. Without contrary explanation, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present invention; the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0165] For convenience of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above-mentioned", etc. can be used here to describe the spatial positional relationship of one device or feature shown in the drawings with other devices or features. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the drawings for the device. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned as "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above..." can include both orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.

[0166] In addition, it should be noted that the use of words such as "first", "second", etc. to limit components is only for the convenience of distinguishing the corresponding components. Without otherwise stating, the above words have no special meaning. Therefore, it should not be construed as a limitation on the protection scope of the present invention.

[0167] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for real-time on-orbit target positioning, characterized in that, The method includes: Obtaining the orbital position coordinates at the satellite imaging moment; Establishing an external calibration parameter model and a resection geometric imaging model for the area array camera's observation of the sky, and obtaining the corrected camera mounting angle and the rotation matrix from the corrected satellite body coordinate system to the camera coordinate system based on the external calibration parameter model and the resection geometric imaging model; Establishing an internal calibration parameter model for the detector area array element pointing angle and an adjustment model, and obtaining the corrected camera pointing angle based on the internal calibration parameter model and the adjustment model; Determining the attitude quaternion of the satellite body coordinate system relative to the J2000 inertial coordinate system based on the star sensor and gyro combined attitude determination algorithm, and obtaining the attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the corrected imaging moment based on the attitude quaternion; Obtaining the updated pitch angle and roll angle of the imaging optics in the satellite orbit coordinate system based on the corrected camera pointing angle and the actual side viewing angle during the optical camera's observation of the ground; Establishing a resection geometric imaging model for the area array optical satellite's observation of the ground based on the orbital position coordinates at the satellite imaging moment, the corrected camera mounting angle, the rotation matrix from the corrected satellite body coordinate system to the camera coordinate system, the attitude rotation matrix from the corrected body coordinate system to the J2000 inertial coordinate system at the imaging moment, and the updated pitch angle and roll angle of the imaging optics in the satellite orbit coordinate system; Obtaining the position coordinates of the target point based on the resection geometric imaging model for the area array optical satellite's observation of the ground and the ellipsoid equation.

2. The method according to claim 1, characterized in that, Obtaining the orbital position coordinates at the satellite imaging moment includes: The on-board receiver obtains observation data in real time; Using Kalman filtering to eliminate the pseudo-range gross error in the observation data, and obtaining the observation data after eliminating the pseudo-range gross error; Based on the observation data after eliminating the pseudo-range gross error, using geometric orbit to obtain the real-time single-point positioning and speed information of the satellite; Performing extended Kalman filtering on the real-time single-point positioning and speed information of the satellite to estimate the state parameters of the satellite; Performing Hermite polynomial interpolation on the state parameters of the satellite to obtain the orbital position coordinates at the satellite imaging moment.

3. The method according to claim 1 or 2, characterized in that, Establishing an external calibration parameter model and a resection geometric imaging model for the area array camera's observation of the sky, and obtaining the corrected camera mounting angle based on the external calibration parameter model and the resection geometric imaging model includes: Obtaining the star map data; Extracting the right ascension and declination of the stars from the star map data with the assistance of the navigation star catalog; Establishing an external calibration parameter model based on the right ascension and declination of the stars and the camera mounting angle; Obtaining the star observation vector based on the right ascension and declination of the stars; Establishing a resection geometric imaging model for the area array camera's observation of the sky based on the collinear relationship between the star observation vector and the satellite payload line of sight pointing vector; Establishing the first adjustment equation and the first error equation based on the external calibration parameter model and the resection geometric imaging model, and using the least squares adjustment method to iteratively solve the first adjustment equation and the first error equation until the external calibration parameters converge, and correcting the camera mounting angle based on the converged external calibration parameters to obtain the corrected camera mounting angle; Obtaining the rotation matrix from the corrected satellite body coordinate system to the camera coordinate system based on the corrected camera mounting angle.

4. The method according to any one of claims 3, characterized in that, The geometric imaging model of resection for the sky observation by the area array camera is established by the following formula: The first adjustment equation is established by the following formula: Among them, The first error equation is established by the following formula: Among them, The corrected camera mounting angle is obtained by the following formula: α′＝α+dα β′＝β+dβ γ′ = γ + dγ Wherein, are the pitch angle and the yaw angle respectively, μ is the scaling factor, is the rotation matrix from the satellite body coordinate system to the camera coordinate system, (α, β, γ) are the installation angles of the optical camera on the satellite body, α, β, and γ are the azimuth angle, pitch angle, and yaw angle of the optical camera on the satellite body respectively, is the rotation matrix from the J2000 inertial coordinate system to the satellite body coordinate system, (r, p, y) are the attitude angles of the satellite body relative to the J2000 inertial coordinate system, r, p, and y are the roll angle, pitch angle, and yaw angle of the satellite body relative to the J2000 inertial coordinate system respectively, R Aber is the aberration correction matrix, α0 and δ0 are the right ascension and declination respectively, G x 、G y are the vector residual functions of the image point along the track and perpendicular to the track directions in the image space coordinate system respectively, is the vector of the observed star in the X, Y, and Z directions in the camera coordinate system, is the error value of the i-th star control point in the star camera coordinate system, A i is the coefficient matrix of the error equation of the star control point, L i is the constant vector of the error equation of the star control point, x = [dα, dβ, dγ] T is the correction vector of the three external calibration parameters, α′, β′, and γ′ are the azimuth angle, pitch angle, and yaw angle of the optical camera on the satellite body after calibration respectively.

5. The method according to any one of claims 1-3, characterized in that, The internal calibration parameter model and adjustment model of the detector area array element pointing angle are established, and the corrected camera pointing angle is obtained based on the internal calibration parameter model and adjustment model, including: The internal calibration parameter model of the detector area array element pointing angle is established; The overlapping ground images are obtained through attitude maneuvering, the point matching is obtained based on the overlapping ground images, the position coordinates of the ground points in the WGS84 coordinate system are obtained based on the point matching, and the adjustment model is established based on the point matching, the position coordinates of the ground points in the WGS84 coordinate system, and the resection geometric imaging model; Based on the internal calibration parameter model and the adjustment model, the second adjustment equation and the second error equation are established, and the least squares adjustment method is used to iteratively solve the second adjustment equation and the second error equation until the internal calibration parameters converge. Based on the converged internal calibration parameters, the camera pointing angle is corrected to obtain the corrected camera pointing angle.

6. The method according to claim 5, wherein The internal calibration parameter model of the detector area array element pointing angle is established by the following formula: The adjustment model is established by the following formula: The second adjustment equation is established by the following formula: The second error equation is established by the following formula: Where \(s\) and \(l\) are the row and column of the CMOS detector element number respectively, and \((a_0, \ldots, a_9, b_0, \ldots, b_9)\) are the internal calibration parameters of the on-orbit geometry. are the X, Y, and Z direction vectors of the ground overlapping image points in the camera coordinate system. is the rotation matrix from the WGS84 coordinate system to the J2000 inertial coordinate system, X g , Y g , Z g are the X, Y, and Z direction position coordinates of the ground points in the WGS84 coordinate system respectively, X gps , Y gps , Z gps are the X, Y, and Z direction orbital position coordinates of the satellite imaging moment in the WGS84 coordinate system respectively, F x , F y are the vector residual functions of the image points along and perpendicular to the track in the image space coordinate system respectively. and are the correction vector corresponding to the image points on the left and right images respectively, \(y = [da_1, \ldots, da_9, db_1, \ldots, db_9]\) T is the correction vector of the camera internal calibration parameters. and are the partial derivative coefficient matrices corresponding to the calibration parameters in the left and right image point error equations respectively. and are the partial derivative coefficient matrices corresponding to the object space coordinates in the left and right image point error equations respectively. and are the constant vectors in the left and right image point error equations respectively. represents the object space plane coordinate correction vector of each homologous image point.

7. The method according to claim 1, characterized in that, The attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the corrected imaging time is obtained by the following formula: In the formula, is the attitude rotation matrix from the body coordinate system to the J2000 inertial coordinate system at the corrected imaging time, is the attitude rotation matrix from the J2000 inertial coordinate system to the body coordinate system at the corrected imaging time, and q = [q0 q1 q2 q3] T is the attitude quaternion, and q0, q1, q2, and q3 are the first, second, third, and fourth elements of the attitude quaternion, respectively.

8. The method according to claim 1, wherein The updated pitch angle of the imaging optics in the satellite orbit coordinate system is obtained by the following formula: The updated yaw angle of the imaging optics in the satellite orbit coordinate system is obtained by the following formula: Among them, In the formula, are the updated pitch angle and yaw angle respectively, are the corrected pitch angle and yaw angle respectively, χ is the actual side view angle, χ0 is the original side view angle, R is the satellite altitude, H is the satellite orbital radius, and δθ is the line-of-sight angle deviation of the optical remote sensing satellite for earth observation.

9. The method according to claim 1, characterized in that, The geometric imaging model of intersection for the area array optical satellite's earth observation is established by the following formula: The ellipsoid equation is established by the following formula: Wherein, X, Y, and Z are the position coordinates of the target point in the X, Y, and Z directions, a and b are respectively the major semi-axis and minor semi-axis of the WGS84 reference ellipsoid, and h is the height of the ground target point corresponding to the image point from the reference ellipsoid surface.

10. A computer device, characterized in that, It includes a memory, a processor, and an on-orbit real-time target positioning program stored on the memory and operable on the processor. When the processor executes the on-orbit real-time target positioning program, it implements the method according to any one of claims 1 to 9.

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