Aircraft target positioning method and system based on satellite-borne bidirectional scanning imaging system

Abstract

The present invention discloses a method and system for locating aircraft targets based on a satellite-borne bidirectional swing imaging system, which is applied to the field of photoelectric detection and imaging technology. The method comprises: acquiring aircraft bidirectional swing observation data; constructing a strict geometric positioning model for the satellite-borne bidirectional swing system using imaging system parameters and attitude and orbit data; and calculating the aircraft's line of sight vector in a geocentric fixed coordinate system based on this model; constructing a spatial geometric constraint model based on the line of sight vector, and using this spatial geometric constraint model to calculate the aircraft's position. Based on the aircraft's significant infrared radiation characteristics, the infrared detection system enables instant detection of the aircraft target. Simultaneously, the space-based bidirectional swing imaging system acquires aircraft target imaging data at different orbital positions and observation angles. Finally, the spatial geometric constraint relationship is used to solve the problem of calculating the aircraft's altitude in the air, ultimately achieving accurate altitude calculation of the aircraft target in the air.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detection and imaging technology, and more particularly to an aircraft target positioning method and system based on a satellite-borne bidirectional sweep imaging system. Background Art

[0002] The detection, positioning, tracking and real-time status information acquisition of aerial aircraft targets are crucial to national defense security, accurate perception of enemy aircraft situation during wartime, and aerial search and rescue.

[0003] Currently, radar detection is primarily used to obtain real-time position information for moving aircraft targets. The radar-based aircraft detection process involves the following steps: First, the radar transmitter generates a radio frequency signal, which is radiated at a specific angle by the transmitting antenna into the detection space. Then, when the electromagnetic wave hits the target, it is reflected, and the echo signal travels through the radar receiving antenna to the receiver. Finally, the receiver transmits the detection information to the signal processing system, which then acquires information such as the target's range, direction, speed, and shape. However, this method faces two major challenges: First, the detection range is limited by the power of the radar transmitter. Furthermore, electromagnetic wave transmission is subject to loss and absorption, and the curvature of the Earth limits the detection of ground-to-air targets. Furthermore, radar detection is an active detection method, meaning that targets have already been detected and locked onto by the enemy. Second, with some current fighter jets now possessing stealth capabilities, their radar cross-sections have decreased, making it difficult for traditional radar detection methods to effectively detect specific aircraft targets. Considering the distinct infrared radiation characteristics of aircraft targets, infrared imaging systems are essential for immediate detection. Furthermore, a space-based, two-way, swing-scanning imaging system can acquire imaging data from aircraft targets at different orbital positions and observation angles. This allows the position of the aircraft target to be calculated based on the sensor's on-orbit geometric positioning model and spatial geometric relationships. In summary, for future applications in aerial aircraft target detection, research is urgently needed on aircraft position calculation methods based on infrared two-way swing-scanning imaging to meet the demands of significant practical applications. Summary of the Invention

[0004] In view of this, the present invention provides an aircraft target positioning method and system based on a satellite-borne bidirectional sweep imaging system to solve the problems in the background technology.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In one aspect, the present invention discloses a method for locating an aircraft target based on a satellite-borne bidirectional sweep imaging system, comprising the following steps:

[0007] Obtain the aircraft's two-way sweep observation data of the satellite at different times, positions, and observation angles;

[0008] Using imaging system parameters and attitude and trajectory data, a strict geometric positioning model for the spaceborne bidirectional scanning system is constructed according to the geometric imaging principle of the linear array scanning camera.

[0009] Calculate the aircraft's sight vector in the geocentric fixed coordinate system based on the aircraft's position coordinates on the reverse scan observation image at different times, the aircraft's position coordinates on the forward scan observation image, and the position angle of the satellite's scanning mirror at the corresponding times;

[0010] A spatial geometric constraint model is constructed based on the sight vector, and the position of the aircraft is solved using the spatial geometric constraint model.

[0011] Preferably, in the above-mentioned aircraft target positioning method based on the satellite-borne bidirectional swing scanning imaging system, the specific steps for acquiring aircraft observation data are as follows: the bidirectional swing scanning imaging system is carried on a low-orbit satellite platform, and at time t1, the bidirectional swing scanning system is in a reverse scanning imaging process, observing the aircraft target, and the projection point of the aircraft on the ground is located at position S1; similarly, at time t2, the bidirectional swing scanning system is in a forward scanning imaging process, observing the aircraft target, and the projection point of the aircraft on the ground is located at position S2.

[0012] Preferably, in the above-mentioned aircraft target positioning method based on a satellite-borne bidirectional sweep imaging system, a strict geometric positioning model of the satellite-borne bidirectional sweep imaging system is constructed, and its expression is:

[0013]

[0014] in, is the position vector of the image point (i, j) in the pixel coordinate system and its object point in the geocentric fixed coordinate system;

[0015] is the position vector of the satellite projection center in the geocentric fixed coordinate system;

[0016] λ is the scaling factor;

[0017] R ref (θ) is the plane reflection matrix corresponding to the scanning angle θ of the scanning mirror;

[0018] θ is the scanning angle value of the scanning mirror;

[0019] is the transformation relationship between the geocentric inertial coordinate system and the geocentric fixed coordinate system;

[0020] The transformation matrix from the satellite's body coordinate system to the Earth's center inertial coordinate system usually includes the satellite's attitude angle (pitch, roll, yaw) calculation;

[0021] pitch, roll, yaw are the three attitude angles of the satellite: pitch angle, roll angle and yaw angle;

[0022] is the calibrated installation matrix of the camera in the satellite body coordinate system, and the installation matrix has been accurately calibrated before the satellite is launched;

[0023] (i0, j0) is the coordinate of the camera principal point in the pixel coordinate system;

[0024] Δi0, Δj0 are the principal point offset errors;

[0025] Δx, Δy are the offset errors of the image point on the image plane;

[0026] dx,dy are the dimensions of the pixel in the x and y directions;

[0027] f is the camera principal distance;

[0028] Δf is the main distance error;

[0029] ||·|| represents a vector normalization operation.

[0030] Preferably, in the above-mentioned aircraft target positioning method based on the satellite-borne bidirectional swing imaging system, the position of the aircraft on the backscan observation image at time t1 is (i1, j1), and the position on the forward scan observation image at time t2 is (i2, j2), then the line of sight vector of the aircraft in the geocentric fixed coordinate system can be solved as

[0031]

[0032]

[0033] in, and are the sight vectors of the aircraft in the geocentric fixed coordinate system at time t1 and time t2 respectively;

[0034] pitch1, roll1, yaw1 and pitch2, roll2, yaw2 are the three attitude angles of the satellite at time t1 and time t2 respectively: pitch angle, roll angle and yaw angle;

[0035] θ1 and θ2 are the position angles of the satellite’s scanning mirror at time t1 and time t2 respectively;

[0036] (i1, j1) and (i2, j2) are the position coordinates of the aircraft on the backscan and forward scan images at time t1 and t2, which can be obtained by the center of gravity extraction algorithm;

[0037] ||·|| represents the normalized unit vector.

[0038] Preferably, in the above-mentioned aircraft target positioning method based on a satellite-borne bidirectional sweep imaging system, the specific steps of constructing a spatial geometric constraint model are as follows:

[0039] Taking the scanning cycle into consideration, the satellite orbit altitude at different times during two consecutive observations is considered to be the same as the aircraft flight altitude at different times;

[0040] Using the fact that the height ratio of similar triangles is equal to the side length ratio, a height constraint relationship is constructed;

[0041] Use the closed graph vector sum to be 0 to construct the speed constraint relationship.

[0042] Preferably, in the above-mentioned aircraft target positioning method based on a satellite-borne bidirectional sweep imaging system, the specific steps of constructing a spatial geometric constraint model are as follows:

[0043] Determine that the satellite is at position A and position B on the orbit at time t1 and time t2, respectively, obtained from the satellite orbit information;

[0044] The aircraft target is located at position N and position M, and F and E are the projection positions of the aircraft target at position N and position M on the ground;

[0045] Determine the satellite orbit height as H; let the lengths of line segment AN and line segment BM be α and β respectively; the aircraft has the same height h at positions M and N, and the aircraft's flight speed v from position N to position M is known; then the following geometric constraints are obtained:

[0046] Height Constraint:

[0047]

[0048] Right now,

[0049]

[0050] Speed ​​Constraints:

[0051]

[0052] Δt=t2-t1 (7).

[0053] Preferably, in the above-mentioned aircraft target positioning method based on a satellite-borne bidirectional sweep imaging system, the specific steps of calculating the aircraft position using the spatial geometric constraint model are as follows:

[0054] Determine the common perpendicular line segment of the two non-planar sight lines of the aircraft target at time t1 and time t2. The common perpendicular line theorem of non-planar straight lines in space can be used to calculate the spatial coordinates of point C and point D.

[0055] When the direction and length of the flight segment NM of the aircraft are determined, there is a line segment that satisfies the constraint conditions on each side of the common perpendicular segment CD; considering the actual spatial movement of the aircraft, only one of the line segments satisfies the actual conditions, and the position coordinates of the aircraft are calculated using the constraint equation based on the relationship between the aircraft position and the two skew lines of sight.

[0056] Preferably, in the above aircraft target positioning method based on a spaceborne two-way swing-scanning imaging system, calculating the position coordinates of the aircraft using the constraint equation based on the relationship between the aircraft position and the two skew lines of sight includes:

[0057] (1) If the line segment BE < BC and the line segment AF < AD, that is, the common perpendicular of the skew lines of sight is located in the space below the ground surface, then points M and N are respectively located on the line segments BE and AF, and α and β are solved through the following constraint equations, and then the position coordinates of the aircraft positions M and N are calculated:

[0058]

[0059] (2) If BE > BC and AF > AD, and the common perpendicular of the skew lines of sight intersects the space line segments BE and AF, then the following judgment needs to be continued:

[0060] 2-1) If MN ≥ EF, then points M and N are respectively located on the line segments BC and AD, and α and β are solved through the following constraint equations, and then the position coordinates of the aircraft positions M and N are calculated:

[0061]

[0062] 2-2) If MN < EF, theoretically there are two line segments NM that meet the conditions above the ground, but considering the actual situation of ground observation where the target line of sight cannot cross in space and then separate, this situation is not considered in practice.

[0063] On the other hand, the present invention discloses an aircraft target positioning system based on a spaceborne two-way swing-scanning imaging system, including:

[0064] An acquisition module, which acquires aircraft observation data of the satellite at different times, different positions, and different observation angles;

[0065] A first construction module, which constructs a strict geometric positioning model of the spaceborne two-way swing-scanning system according to the imaging system parameters and attitude and orbit data based on the geometric imaging principle of the line array swing-scanning camera;

[0066] A first calculation module, which calculates the line-of-sight vector of the aircraft in the geocentric fixed coordinate system according to the position coordinates of the aircraft in the reverse-scanning observation image at different times, the position coordinates of the aircraft in the forward-scanning observation image, and the position angle of the scanning mirror of the satellite at the corresponding time;

[0067] The construction and solution module constructs a spatial geometric constraint model based on the sight vector and uses the spatial geometric constraint model to solve the aircraft position.

[0068] Preferably, in the above-mentioned aircraft target positioning method based on a satellite-borne bidirectional sweep imaging system, the construction and solution module includes:

[0069] Height constraint unit, using the height ratio of similar triangles to be equal to the side length ratio to construct a height constraint relationship;

[0070] The speed constraint unit uses the closed graph vector sum to be 0 to construct the speed constraint relationship;

[0071] The solving unit calculates the position coordinates of the aircraft using the constraint equation according to the relationship between the aircraft position and the two non-planar sight lines.

[0072] It can be seen from the above technical solution that compared with the existing technology, the present invention provides an aircraft target positioning method and system based on a satellite-borne two-way swing imaging system. Based on the significant infrared radiation characteristics of the aircraft target, the infrared detection system is used to realize the instant detection of the aircraft target. At the same time, the imaging data of the aircraft target at different orbital positions and different observation angles are obtained through the space-based two-way swing imaging system. Finally, the problem of calculating the height of the aircraft target in the air is solved based on the line of sight intersection method, and ultimately the accurate calculation of the height of the aircraft target in the air can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0074] Figure 1 is a flow chart of the method of the present invention;

[0075] Figure 2 This is a schematic diagram of the satellite-borne bidirectional sweep imaging of the present invention;

[0076] Figure 3 This is a schematic diagram of the spatial geometric constraint relationship based on the sight vector of the present invention. Figure 1 ;

[0077] Figure 4 This is a schematic diagram of the spatial geometric constraint relationship based on the sight vector of the present invention. Figure 2 ;

[0078] Figure 5 This is a system block diagram of the present invention. DETAILED DESCRIPTION

[0079] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0080] The embodiment of the present invention discloses a method for locating an aircraft target based on a satellite-borne bidirectional sweep imaging system. Figure 1 As shown, first, a two-way sweep imaging system is used to acquire image data of the aircraft at different times, positions, and observation angles. Then, based on the satellite attitude and trajectory data, the sight line vector of the aircraft target on different observation images is calculated based on the strict geometric positioning model of the two-way sweep imaging system. Finally, assuming that the aircraft's flight altitude remains unchanged and its flight direction and speed are known within a scanning cycle, a spatial geometric constraint relationship is constructed based on the continuously observed sight line vectors, and a set of equations is established to achieve the position solution of the aircraft target. This embodiment of the present invention mainly includes the following steps:

[0081] 1. Obtain space-based two-way sweep observation data of aircraft targets:

[0082] like Figure 2 As shown in the figure, the bidirectional sweep imaging system is carried by a low-orbit satellite platform. At time t1, the bidirectional sweep imaging system is in the reverse sweep imaging process (shown in the solid line frame in the figure), observing the aircraft target, and the aircraft's projection on the ground is located at position S1. Similarly, at time t2, the bidirectional sweep imaging system is in the forward sweep imaging process (shown in the dashed line frame in the figure), observing the aircraft target, and the aircraft's projection on the ground is located at position S2. During continuous on-orbit observation, the satellite can obtain aircraft observation data at different times, positions, and observation angles, laying the data foundation for aircraft position calculation.

[0083] 2. Construct a strict geometric positioning model for the onboard bidirectional sweep system:

[0084] According to the geometric imaging principle of the linear array scanning camera, a strict geometric positioning model of the satellite-borne bidirectional scanning system is constructed, and its expression is:

[0085]

[0086] in, is the position vector of the image point (i, j) in the pixel coordinate system and its object point in the geocentric fixed coordinate system;

[0087] is the position vector of the satellite projection center in the geocentric fixed coordinate system;

[0088] λ is the scaling factor;

[0089] R ref (θ) is the plane reflection matrix corresponding to the scanning angle θ of the scanning mirror;

[0090] θ is the scanning angle value of the scanning mirror;

[0091] is the transformation relationship between the geocentric inertial coordinate system and the geocentric fixed coordinate system;

[0092] The transformation matrix from the satellite's body coordinate system to the Earth's center inertial coordinate system usually includes the satellite's attitude angle (pitch, roll, yaw) calculation;

[0093] pitch, roll, yaw are the three attitude angles of the satellite: pitch angle, roll angle and yaw angle;

[0094] is the calibrated installation matrix of the camera in the satellite body coordinate system, and the installation matrix has been accurately calibrated before the satellite is launched;

[0095] (i0, j0) is the coordinate of the camera principal point in the pixel coordinate system;

[0096] Δi0, Δj0 are the principal point offset errors;

[0097] Δx, Δy are the offset errors of the image point on the image plane;

[0098] dx,dy are the dimensions of the pixel in the x and y directions;

[0099] f is the camera principal distance;

[0100] Δf is the main distance error;

[0101] ||·|| represents the normalized unit vector.

[0102] 3. Aircraft target sight vector calculation based on bidirectional scanning images:

[0103] Based on the strict geometric positioning model of the bidirectional scanning imaging system in step 2 above, assuming that the position of the aircraft on the reverse scanning observation image at time t1 is (i1, j1), and the position on the forward scanning observation image at time t2 is (i2, j2), the line of sight vector of the aircraft in the geocentric fixed coordinate system can be solved as

[0104]

[0105]

[0106] in, and are the sight vectors of the aircraft in the geocentric fixed coordinate system at time t1 and time t2 respectively;

[0107] pitch1, roll1, yaw1 and pitch2, roll2, yaw2 are the three attitude angles of the satellite at time t1 and time t2 respectively: pitch angle, roll angle and yaw angle;

[0108] θ1 and θ2 are the position angles of the satellite’s scanning mirror at time t1 and time t2 respectively;

[0109] (i1, j1) and (i2, j2) are the position coordinates of the aircraft on the backscan and forward scan images at time t1 and t2, respectively, which can be obtained by the center of gravity extraction algorithm. The definitions of other quantities are the same as in step 2.

[0110] 4. Construct a spatial geometric constraint model based on the line of sight vector:

[0111] like Figure 3 As shown in the figure, at times t1 and t2, the satellite is located at positions A and B in orbit, respectively. Specific position information can be obtained from the satellite orbit information. The aircraft target is located at positions N and M, with F and E representing the ground projections of the aircraft target at positions N and M. Line segment CD is the common perpendicular segment between the two non-parallel sight lines of the aircraft target at times t1 and t2.

[0112] Assume that the satellite orbit height is H; the lengths of line segment AN and line segment BM are α and β respectively; the aircraft has the same height h at positions M and N, and the aircraft's flight speed v from position N to position M is known; then the following geometric constraints can be obtained:

[0113] (1) Height Constraint

[0114]

[0115] Right now,

[0116]

[0117] (2) Speed ​​constraint

[0118]

[0119] Δt=t2-t1 (7);

[0120] in, is a vector The corresponding unit vector.

[0121] 5. Accurately calculate the aircraft target position based on spatial constraint equations:

[0122] like Figure 3As shown, the line segment CD is the common perpendicular line segment of two skew lines of the aircraft target in space at time t1 and time t2. Then, the spatial coordinates of points C and D can be calculated according to the theorem of the common perpendicular line of skew lines in space.

[0123] As Figure 4 shown, it can be seen from the fact that the distance of the common perpendicular line segment between skew lines is the shortest that when the direction and length of the line segment NM are determined, there is a line segment satisfying the constraint conditions on each side of the common perpendicular line segment CD. Considering the actual movement of the aircraft in space, only one line segment meets the actual conditions, and it can be determined by the following method:

[0124] (1) If the line segment BE < BC and the line segment AF < AD, that is, the common perpendicular line of the skew lines of sight is located in the space below the ground surface, then points M and N are respectively located on the line segment BE and the line segment AF, and α and β can be solved through the following constraint equations, and then the position coordinates of the aircraft positions M and N can be calculated:

[0125]

[0126] (2) If BE > BC and AF > AD, that is, as Figure 3 shown, the common perpendicular line of the skew lines of sight intersects with the space line segments BE and AF, then the following judgment needs to be continued

[0127] 2-1) If MN ≥ EF, then points M and N are respectively located on the line segment BC and the line segment AD, and α and β can be solved through the following constraint equations, and then the position coordinates of the aircraft positions M and N can be calculated:

[0128]

[0129] 2-2) If MN < EF, theoretically there are two line segments NM that meet the conditions above the ground, but considering the actual situation that the target line of sight cannot cross in space and then separate during ground observation, this situation can be not considered in practice.

[0130] Based on the above method, the values of α and β can be obtained, and then the three-dimensional space coordinates of the aircraft can be solved, realizing the spatial positioning of the aircraft target based on the spaceborne two-way pendulum scanning imaging system.

[0131] Another embodiment of the present invention discloses an aircraft target positioning system based on a spaceborne two-way pendulum scanning imaging system, as Figure 5 shown, including:

[0132] An acquisition module, which acquires the two-way pendulum scanning observation data of the aircraft by the satellite at different times, different positions, and different observation angles;

[0133] A first construction module, which constructs a strict geometric positioning model of the spaceborne two-way pendulum scanning system according to the geometric imaging principle of the line array pendulum scanning camera by using the imaging system parameters and attitude and orbit data;

[0134] The first calculation module calculates the aircraft's sight vector in the geocentric fixed coordinate system based on the aircraft's position coordinates on the backscan observation image at different times, the aircraft's position coordinates on the forward scan observation image, and the position angle of the satellite's scanning mirror at the corresponding times;

[0135] The construction and solution module constructs a spatial geometric constraint model based on the sight vector and uses the spatial geometric constraint model to solve the aircraft position.

[0136] In order to further optimize the above technical solution, the construction and solution modules include:

[0137] Height constraint unit, using the height ratio of similar triangles to be equal to the side length ratio to construct a height constraint relationship;

[0138] The speed constraint unit uses the closed graph vector sum to be 0 to construct the speed constraint relationship;

[0139] The solving unit calculates the position coordinates of the aircraft using the constraint equation according to the relationship between the aircraft position and the two non-planar sight lines.

[0140] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0141] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for locating an aircraft target based on a satellite-borne bidirectional sweep imaging system, characterized in that: The following steps are involved: Obtain the aircraft's two-way sweep observation data of the satellite at different times, positions, and observation angles; Using imaging system parameters and attitude and trajectory data, a strict geometric positioning model for the spaceborne bidirectional scanning system is constructed according to the geometric imaging principle of the linear array scanning camera. Calculate the aircraft's sight vector in the geocentric fixed coordinate system based on the aircraft's position coordinates on the reverse scan observation image at different times, the aircraft's position coordinates on the forward scan observation image, and the position angle of the satellite's scanning mirror at the corresponding times; Constructing a spatial geometric constraint model based on the sight vector, and solving the aircraft position using the spatial geometric constraint model; The specific steps to build a spatial geometric constraint model are as follows: Determine that the satellite is at position A and position B on the orbit at time t1 and time t2 respectively. Obtained from satellite orbit information; The aircraft target is located at position N and position M, and F and E are the projection positions of the aircraft target at position N and position M on the ground; Determine the satellite orbit height as H; let the lengths of line segment AN and line segment BM be α and β respectively; the aircraft has the same height h at positions M and N, and the aircraft's flight speed v from position N to position M is known; then the following geometric constraints are obtained: Height Constraint: Right now, Speed ​​Constraints: Δt=t2-t1(7); is a vector The corresponding unit vector; The specific steps for calculating the aircraft position using the spatial geometric constraint model are as follows: Determine the common perpendicular line segment of the two non-planar sight lines of the aircraft target at time t1 and time t2, and calculate the spatial coordinates of points C and D using the common perpendicular line theorem of non-planar straight lines in space; When the direction and length of the aircraft's flight segment NM are determined, there is a line segment on each side of the common perpendicular segment CD that meets the constraint conditions. Considering the actual aircraft motion in space, only one of the line segments meets the actual conditions. The aircraft position coordinates are calculated using the constraint equation based on the relationship between the aircraft position and the two non-planar lines of sight.

2. The method for locating an aircraft target based on a satellite-borne bidirectional sweep imaging system according to claim 1, characterized in that: The specific steps for acquiring aircraft observation data are as follows: the bidirectional swing scanning imaging system is carried on a low-orbit satellite platform. At time t1, the bidirectional swing scanning system is in the reverse scanning imaging process, observing the aircraft target, and the projection point of the aircraft on the ground is located at position S1; similarly, at time t2, the bidirectional swing scanning system is in the forward scanning imaging process, observing the aircraft target, and the projection point of the aircraft on the ground is located at position S2.

3. The method for locating an aircraft target based on a satellite-borne bidirectional sweep imaging system according to claim 1, characterized in that: A strict geometric positioning model of the satellite-borne bidirectional sweep system is constructed, and its expression is: in, is the position vector of the image point (i, j) in the pixel coordinate system and its object point in the geocentric fixed coordinate system; is the position vector of the satellite projection center in the geocentric fixed coordinate system; λ is the scaling factor; R ref (θ) is the plane reflection matrix corresponding to the scanning angle θ of the scanning mirror; θ is the scanning angle value of the scanning mirror; is the transformation relationship between the geocentric inertial coordinate system and the geocentric fixed coordinate system; The transformation matrix from the satellite's body coordinate system to the Earth's center inertial coordinate system usually includes the satellite's attitude angle (pitch, roll, yaw) calculation; pitch, roll, yaw are the three attitude angles of the satellite: pitch angle, roll angle and yaw angle; is the calibrated installation matrix of the camera in the satellite body coordinate system, and the installation matrix has been accurately calibrated before the satellite is launched; (i0, j0) is the coordinate of the camera principal point in the pixel coordinate system; Δi0, Δj0 are the camera principal point offset errors; Δx, Δy are the offset errors of the image point on the image plane; dx,dy are the dimensions of the pixel in the x and y directions; f is the camera principal distance; Δf is the camera principal distance error; ||·|| represents a vector normalization operation.

4. The method for locating an aircraft target based on a satellite-borne bidirectional sweep imaging system according to claim 3, characterized in that: The position of the aircraft on the backscan observation image at time t1 is (i1, j1), and the position on the forward scan observation image at time t2 is (i2, j2). The line of sight vector of the aircraft in the geocentric fixed coordinate system is calculated as: in, and are the sight vectors of the aircraft in the geocentric fixed coordinate system at time t1 and time t2 respectively; pitch1, roll1, yaw1 and pitch2, roll2, yaw2 are the three attitude angles of the satellite at times t1 and t2 respectively: pitch angle, roll angle and yaw angle; θ1 and θ2 are the position angles of the scanning mirror of the satellite at times t1 and t2 respectively; (i1, j1) and (i2, j2) are the position coordinates of the aircraft on the reverse scan and forward scan images at times t1 and t2 respectively, which are obtained by the centroid extraction algorithm.

5. The method for locating an aircraft target based on a satellite-borne bidirectional sweep imaging system according to claim 1, characterized in that: The specific steps for constructing the spatial geometric constraint model are as follows: Considering the scanning period duration, the satellite operating orbit altitude at different times and the aircraft flight altitude at different times are regarded as the same during two consecutive observations; Using the fact that the height ratio of similar triangles is equal to the side length ratio, a height constraint relationship is constructed; Using the fact that the vector sum of a closed figure is 0, a speed constraint relationship is constructed.

6. The method for locating an aircraft target based on a satellite-borne bidirectional sweep imaging system according to claim 1, characterized in that: According to the relationship between the aircraft position and two skew lines of sight, the aircraft position coordinates are calculated using the constraint equations, including: (1) If the line segment BE < BC and the line segment AF < AD, that is, the common perpendicular of the skew lines of sight is located in the space below the ground surface, then points M and N are respectively located on the line segment BE and the line segment AF, and α and β are solved through the following constraint equations, and then the position coordinates of the aircraft positions M and N are calculated: (2) If BE > BC and AF > AD, and the common perpendicular of the skew lines of sight intersects the space line segments BE and AF, then the following judgment needs to be continued: 2 - 1) If MN ≥ EF, then points M and N are respectively located on the line segment BC and the line segment AD, and α and β are solved through the following constraint equations, and then the position coordinates of the aircraft positions M and N are calculated: 2 - 2) If MN < EF, then theoretically there are two line segments NM that meet the conditions above the ground, but considering that in actual ground observation, the target line of sight cannot cross in space and then separate, so this situation is not considered in practice.

7. An aircraft target positioning system based on a satellite-borne bidirectional sweep imaging system, characterized in that: Including: An acquisition module that acquires the aircraft two-way swing scan observation data of the satellite at different times, different positions, and different observation angles; A first construction module that constructs a strict geometric positioning model of the spaceborne two-way swing scan system according to the imaging system parameters and the attitude and orbit data based on the geometric imaging principle of the line array swing scan camera; A first solution module that calculates the line of sight vector of the aircraft in the geocentric fixed coordinate system according to the position coordinates of the aircraft on the reverse scan observation image at different times, the position coordinates of the aircraft on the forward scan observation image, and the position angle of the scanning mirror of the satellite at the corresponding times; A construction and solution module that constructs a spatial geometric constraint model based on the line of sight vector and calculates the aircraft position using the spatial geometric constraint model; The specific steps for constructing the spatial geometric constraint model are as follows: It is determined that the satellite is located at positions A and B on the orbit at times t1 and t2 respectively, Obtained from the satellite orbit information; The aircraft target is located at positions N and M, and F and E are the projection positions of the aircraft targets at positions N and M on the ground; It is determined that the satellite orbit altitude is H; let the lengths of the line segments AN and BM be α and β respectively; the aircraft has the same altitude h at M and N, and the flight speed v of the aircraft from position N to position M is known; then the following geometric constraint relationships are obtained: Height constraint: That is, Speed constraint: Δt = t2 - t1 (7); is a vector The corresponding unit vector; The specific steps for calculating the aircraft position using the spatial geometric constraint model are as follows: Determine the common perpendicular line segment of the two non-planar sight lines of the aircraft target at time t1 and time t2, and calculate the spatial coordinates of points C and D using the common perpendicular line theorem of non-planar straight lines in space; When the direction and length of the aircraft's flight segment NM are determined, there is a line segment on each side of the common perpendicular segment CD that meets the constraint conditions. Considering the actual aircraft motion in space, only one of the line segments meets the actual conditions. The aircraft position coordinates are calculated using the constraint equation based on the relationship between the aircraft position and the two non-planar lines of sight.

8. The aircraft target positioning system based on a satellite-borne bidirectional sweep imaging system according to claim 7, characterized in that: The construction and solution modules include: Height constraint unit, using the height ratio of similar triangles to be equal to the side length ratio to construct a height constraint relationship; The speed constraint unit uses the closed graph vector sum to be 0 to construct the speed constraint relationship; The solving unit calculates the position coordinates of the aircraft using the constraint equation according to the relationship between the aircraft position and the two non-planar sight lines.

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