A method for obtaining the optimal intersection point of spatial non-planar target intersection imaging

Abstract

The present invention discloses a method for obtaining the optimal intersection point of space non-planar target rendezvous imaging. According to the space rendezvous imaging task requirements, the active spacecraft attitude and payload constraints are considered, all intersection point parameters that meet the conditions are given, and the optimal intersection point parameters are screened out based on a clustering algorithm; the intersection point parameters are defined as the height difference and phase difference between the active spacecraft and the target satellite at the intersection point.

Description

Technical Field

[0001] This patent involves the field of space rendezvous and situational awareness, and specifically involves a method for obtaining the optimal intersection point for rendezvous imaging of space non-planar targets. It performs technical decomposition based on the requirements of space imaging tasks and designs intersection point parameters that meet imaging constraints. Background Art

[0002] With the increasing number of spacecraft, rocket bodies, space debris and other space targets in orbit, the space environment is deteriorating, posing a serious, continuous and widespread threat to the normal operation of spacecraft, subsequent space missions and the development of future space industry. In order to ensure the safety of space assets and make full use of space, fully understanding the comprehensive information of space targets and environment and ultimately obtaining space situation has become the ultimate goal of the construction of space forces in various countries in the world.

[0003] One of the important uses of the space situational awareness system is to image space targets. If the imaging is done by natural rendezvous, it is very likely that the desired target image will not be obtained due to the constraints of space dynamics and physical position. Therefore, it is a reliable and controlled imaging method for the spacecraft to rendezvous with the target through maneuvering and changing the orbit. This also means that the control strategy can be designed to make the relative position of the spacecraft and the target meet the mission requirements at the intersection point, and obtain the desired target information.

[0004] For visible light payloads, the relative position of the spacecraft and the target at the intersection point determines whether the desired target image information can be obtained. Taking into full consideration the laws of space orbit operation and the constraints of spacecraft payload parameters, what relative position can enable the spacecraft to still meet the conditions for imaging the target at the intersection point after maneuvering and changing orbits and meet the mission requirements is a difficult problem in the design of intersection point parameters, and is also one of the problems to be solved by this patent.

[0005] There are generally many groups of relative positions of the spacecraft and the target at the intersection point (i.e., intersection point parameters) that meet the imaging mission constraints. How to evaluate the advantages and disadvantages of the intersection point parameters and how to select a set of reasonable and mission-optimal parameters from multiple groups of intersection point parameters are one of the problems to be solved by this patent.

[0006] Through the recent investigation of related fields, it is found that the most researched aspects of space rendezvous are control strategies, while the research on terminal conditions, i.e., the final rendezvous target, is less. The intersection point parameters are the key to whether the space rendezvous imaging mission can be performed as expected. Summary of the invention

[0007] The purpose of the present invention is to provide a method for obtaining the optimal intersection point of spatial non-planar target intersection imaging, using an analytical formula to solve the intersection point parameters that meet the imaging conditions, and screening out the optimal intersection point parameters based on a clustering algorithm.

[0008] The technical solution of the present invention is: a method for obtaining the optimal intersection point for rendezvous imaging of space non-planar targets, according to the space rendezvous imaging task requirements, considering the active spacecraft attitude and payload constraints, giving all intersection point parameters that meet the conditions, and screening out the optimal intersection point parameters based on a clustering algorithm; the intersection point parameters are defined as the height difference and phase difference between the active spacecraft and the target satellite at the intersection point.

[0009] Further, the specific steps are as follows:

[0010] Step 1: According to the requirements of the space rendezvous imaging mission, the altitude difference and phase difference search range between the active spacecraft and the target satellite at the intersection point is set, and the position and velocity of the active spacecraft and the target satellite at the intersection point are calculated according to the orbital parameters of the active spacecraft and the target satellite;

[0011] Step 2: According to the relative positions of the active spacecraft and the target satellite at the intersection point, considering the active spacecraft attitude and payload working constraints, determine whether the intersection point parameters can meet the mission requirements. If they meet the mission requirements, the set of intersection point parameters is considered feasible and stored in the feasible solution matrix.

[0012] Step 3: Considering the influence of perturbation iteration on the final intersection accuracy, a clustering algorithm is used to obtain the optimal intersection point parameters for all feasible solutions of the intersection point parameters.

[0013] Furthermore, step one is as follows:

[0014] Assuming that the height difference and phase difference between the active spacecraft and the target satellite at the intersection point are (Δh, Δf), the position and velocity of the active spacecraft and the target satellite at the intersection point are calculated as follows:

[0015] (a) Determine the latitude argument of the intersection point between the active spacecraft and the target satellite;

[0016] According to the adjacent four-element formula of the spherical triangle, we get:

[0017]

[0018] In the formula, u sc is the latitude argument of the rendezvous point of the active spacecraft, u tc is the latitude argument of the intersection point of the target satellite, Ω s is the right ascension of the ascending node of the active spacecraft, Ω t is the right ascension of the target satellite ascending node, i s is the active spacecraft inclination angle, i t is the target satellite inclination;

[0019] (b) Determine the rate of change of latitude argument of the active spacecraft and the target satellite;

[0020]

[0021] In the formula, u s is the latitude argument of the active spacecraft, u t is the latitude argument of the target satellite, r s is the distance from the center of the Earth to the active spacecraft, r t are the geocentric distances of the target satellites respectively;

[0022] (c) Determine the latitude arguments before and after the intersection point;

[0023]

[0024] In the formula, u sc is the latitude argument of the active spacecraft at the rendezvous point, u tc is the latitude argument of the target satellite at the intersection point, Δf is the true anomaly difference between the active spacecraft and the target satellite at the intersection point, Δt is the running time, and u s0 is the latitude argument at the start time of active spacecraft calculation, u t0 The latitude argument at the start time calculated for the target satellite, u sf is the latitude argument at the terminal moment calculated by the active spacecraft, u tf The latitude argument at the terminal time calculated for the target satellite;

[0025] (d) The target orbital radius vector of the known intersection point is r t , r s =r t +Δh, from which the position and velocity of the active spacecraft near the intersection point are obtained;

[0026] R sx =r s (cosΩ s cosu s -sinΩ s cosi s Sinu s )

[0027] R sy =r s (sinΩ s cosu s +cosΩ s cosi s Sinu s )

[0028] R sz =r s (sini s Sinu s )

[0029]

[0030]

[0031] In the formula, R sx is the X-direction position of the active spacecraft J2000, R sy is the Y-direction position of the active spacecraft J2000, R sz is the Z-direction position of the active spacecraft J2000, V sx is the velocity in the X direction of the active spacecraft J2000 system, V sy is the velocity of the active spacecraft J2000 in the Y direction, V sz is the velocity in the Z direction of the active spacecraft J2000 system;

[0032] Similarly, the position and velocity of the target satellite near the rendezvous point can be obtained: RV t =[R tx , R ty , R tz , V tx , V ty , V tz ], R tx is the X-direction position of the target J2000 system, R ty is the Y-direction position of the target J2000 system, R tz is the Z-direction position of the target J2000 system, V tx is the velocity of the target satellite in the X direction in the J2000 system, V ty is the velocity of the target satellite in the Y direction in the J2000 system, V tz is the speed of the target satellite in the Z direction in the J2000 system.

[0033] Furthermore, step 2 is specifically as follows: the constraints of the active spacecraft approaching the target satellite for imaging are as follows: the imaging distance is less than the maximum imaging distance constraint of the payload, the azimuth angle and the pitch angle are within the maximum working angle range of the spacecraft rotation mechanism, and the sun angle and the earth angle meet the minimum imaging angle constraint;

[0034] The specific screening method is as follows:

[0035]

[0036] In the formula, R max is the maximum relative distance between the active spacecraft and the target satellite;

[0037] θ min ,θ max are the minimum and maximum values ​​of the azimuth, respectively. The azimuth refers to the position of the target satellite relative to the active spacecraft in the VVLH coordinate system;

[0038] are the minimum and maximum values ​​of the pitch angle, respectively. The pitch angle refers to the pitch of the target satellite relative to the active spacecraft in the VVLH coordinate system;

[0039] are the minimum and maximum values ​​of the azimuth angular velocity respectively;

[0040] are the minimum and maximum values ​​of the pitch angle velocity respectively;

[0041] α min is the minimum value of the solar angle, which is defined as the angle between the target satellite pointing to the active spacecraft vector and the target satellite pointing to the sun vector;

[0042] β min is the minimum value of the Earth-atmosphere angle. The Earth-atmosphere angle is the angle between the Earth-atmosphere light and refers to the angle between the active spacecraft’s vector pointing to the center of the Earth and the active spacecraft’s vector pointing to the target satellite.

[0043] If there is a solution that satisfies the above conditions, the set of intersection point parameters (Δh, Δf) is considered to meet the imaging conditions and is stored in the feasible solution matrix [(Δh i ,Δf i )]middle.

[0044] Furthermore, step three is as follows: Considering the influence of spatial perturbation on the final imaging effect, the intersection point parameters should select the feasible solution matrix [(Δh i ,Δf i )], that is, the more feasible solutions around the selected (Δh, Δf), the better.

[0045] Furthermore, the mean shift algorithm in the clustering algorithm is used to solve the optimal (Δh, Δf) as follows:

[0046] (1) In the feasible solution matrix [(Δh i ,Δf i )] randomly select a group as the center (Δh0, Δf0);

[0047] (2) Given a search radius r, find all points whose distance from (Δh0, Δf0) is less than r, recorded as set M, and consider these points to belong to category c. At the same time, the number of visits to these points in category c is increased by 1;

[0048] (3) Taking (Δh0, Δf0) as the center point, calculate the vector from (Δh0, Δf0) to each element in the set M, and add these vectors to obtain the drift M. r ;

[0049] (4) Update the center point (Δh0, Δf0) = (Δh0, Δf0) + Mr , indicating that (Δh0, Δf0) is along the direction M r Moved distance ||M r ||;

[0050] (5) Repeat steps (2) to (4) until ||M r || is less than the set threshold, stop the iteration, remember (Δh0, Δf0) at this time, all points in this iteration process belong to category c;

[0051] (6) If the center of the current category c and the center of the existing category c′ are less than the threshold during convergence, then the current c should belong to the same category as c′ and be merged into c′; otherwise, c is treated as a new category and an additional category is added;

[0052] (7) Repeat (2) to (4) until all points are marked as visited;

[0053] (8) Classification: Find the category with the most visits for each point and assign it to that category;

[0054] (9) The center of the class with the largest number of points is the optimal intersection parameter.

[0055] The beneficial effect of the present invention is to provide a method for solving the intersection points of the intersection imaging of space heterogeneous targets. This method is suitable for the task of close-range imaging of space heterogeneous targets by remote sensing satellites. It performs analytical solutions for different load constraints and task requirements, and selects the optimal intersection point parameters based on a clustering algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The drawings in the specification of this patent mainly assist in understanding this patent through graphics, specifically including:

[0057] Figure 1 A typical spherical triangle in a skew orbital rendezvous;

[0058] Figure 2 Intersection point parameters that meet task requirements;

[0059] Figure 3 Mean shift solution process;

[0060] Figure 4 Optimal intersection point parameters. DETAILED DESCRIPTION

[0061] The present invention will be further described below in conjunction with the accompanying drawings.

[0062] According to the requirements of the space rendezvous imaging mission, considering the active spacecraft attitude and payload constraints, all the intersection point parameters that meet the conditions are given, and the optimal intersection point parameters are screened out based on the clustering algorithm. The intersection point parameters are defined as the height difference and phase difference between the active spacecraft and the target satellite at the intersection point.

[0063] In order to illustrate the above invention, this patent adopts the following technical solution:

[0064] Firstly, according to the requirements of the space rendezvous imaging mission, the altitude difference and phase difference search range between the active spacecraft and the target satellite at the intersection point is set, and the position and velocity of the active spacecraft and the target satellite at the intersection point are calculated according to the orbital parameters of the active spacecraft and the target satellite.

[0065] Secondly, according to the relative positions of the active spacecraft and the target satellite at the intersection point, considering the active spacecraft attitude and payload working constraints, it is judged whether the intersection point parameters can meet the mission requirements. If they meet the mission requirements, the set of intersection point parameters is considered feasible and stored in the feasible solution matrix.

[0066] Finally, considering the influence of perturbation iteration on the final intersection accuracy, a clustering algorithm is used to obtain the optimal intersection point parameters for all feasible solutions of intersection point parameters.

[0067] Furthermore, the specific implementation steps of this technical solution are introduced as follows:

[0068] Step 1: Calculate the position and velocity of the active spacecraft and the target satellite at the intersection point

[0069] Assuming that the target satellite does not perform orbital maneuvers, some orbital parameters of the target satellite at the intersection point are known, and only the latitude argument cannot be determined. In order to save fuel consumption, the active spacecraft only changes its orbit within the orbital plane, so its parameters outside the orbital plane are known. Assuming that the eccentricity of the active spacecraft is small, the orbital parameters of the active spacecraft at the intersection point are only the radial vector and the latitude argument unknown.

[0070] Assuming that the height difference and phase difference between the active spacecraft and the target satellite at the intersection point are (Δh, Δf), the position and velocity of the active spacecraft and the target satellite at the intersection point are calculated as follows.

[0071] (1) Method for determining the latitude argument of the intersection point between the active spacecraft and the target satellite.

[0072] Figure 1In the figure, orbit 1 is the parking orbit of the active spacecraft, orbit 2 is the target orbit of the target satellite, point F is the center of mass of the earth, the intersection line of the two orbital planes is FF'F", point F' is the intersection point of orbit 1 and the intersection line FF'F", and point F" is the intersection point of orbit 2 and the intersection line FF'F". Track 3 is the derivative of orbit 2 in the parking orbital plane after rotating δ angle along the intersection line FF'F" with the intersection point F" as the rotation point. Track 4 is the derivative of orbit 1 in the target orbital plane after rotating δ angle along the intersection line FF'F".

[0073] like Figure 1 As shown, u sc is the angle between the intersection line FF'F" of orbit 1 and orbit 2 and the node line of orbit 1, that is, the latitude argument of the intersection point of the active spacecraft, u tc It is the angle between the intersection line FF'F" of orbit 1 and orbit 2 and the node line of orbit 2, that is, the latitude argument of the intersection point of the target satellite. According to the adjacent four-element formula of the spherical triangle, it is obtained:

[0074]

[0075] In the formula, Ω s / Ω t is the right ascension of the ascending node of the active spacecraft / target satellite; i s / i t is the active spacecraft / target satellite inclination.

[0076] (2) Latitude argument change rate of active spacecraft and target satellite:

[0077]

[0078] In the formula, u s / u t are the latitude arguments of the active spacecraft and the target satellite, r s / r t are the geocentric distances of the active spacecraft and the target satellite, respectively.

[0079] (3) The latitude angle before and after the intersection point can be expressed by the following formula:

[0080]

[0081] In the formula, u sc / u tc are the latitude arguments of the active spacecraft and the target satellite at the intersection point, Δf is the true anomaly difference between the active spacecraft and the target satellite at the intersection point, Δt is the running time, and u s0 / u t0 are the latitude arguments at the start time of calculation for the active spacecraft and the target satellite, respectively, u sf / u tfare the latitude arguments at the terminal moments calculated for the active spacecraft and the target satellite, respectively.

[0082] (4) The target orbital radius vector of the known intersection point is r t , r s =r t +Δh, from which the position and velocity of the active spacecraft near the intersection point can be obtained.

[0083] R sx =r s (cosΩ s cosu s -sinΩ s cosi s Sinu s )

[0084] R sy =r s (sinΩ s cosu s +cosΩ s cosi s Sinu s )

[0085] R sz =r s (sini s Sinu s )

[0086]

[0087] In the formula, R sx is the X-direction position of the active spacecraft J2000, R sy is the Y-direction position of the active spacecraft J2000, R sz is the Z-direction position of the active spacecraft J2000, V sx is the velocity in the X direction of the active spacecraft J2000 system, V sy is the velocity of the active spacecraft J2000 in the Y direction, V sz is the velocity in the Z direction of the active spacecraft J2000 system.

[0088] Similarly, the position and velocity of the target satellite near the rendezvous point can be obtained: RV t =[R tx , R ty , R tz , V tx , V ty , V tz ], R tx is the X-direction position of the target J2000 system, R tyis the Y-direction position of the target J2000 system, R tz is the Z-direction position of the target J2000 system, V tx is the velocity of the target satellite in the X direction in the J2000 system, V ty is the velocity of the target satellite in the Y direction in the J2000 system, V tz is the speed of the target satellite in the Z direction in the J2000 system.

[0089] Step 2: Determine whether the intersection point parameters can meet the task requirements

[0090] Generally speaking, the spacecraft payload working constraints need to consider the relative distance, azimuth and pitch angles, as well as the solar angle and geoatmospheric angle. According to step 1, the relative position and velocity of the spacecraft and the target can be obtained. The method for calculating the payload working constraints based on the relative position and velocity is as follows.

[0091] (1) Relative distance

[0092] The position of the active spacecraft in the J2000 system R s =[R sx ,R sx ,R sz ], R sx is the X-direction position of the active spacecraft J2000, R sy is the Y-direction position of the active spacecraft J2000, R sz is the Z-direction position of the active spacecraft in the J2000 system. The position of the target satellite in the J2000 system is R t =[R tx ,R tx ,R tz ], R tx is the X-direction position of the target J2000 system, R ty is the Y-direction position of the target J2000 system, R tz is the Z-direction position of the target in the J2000 system. The relative position vector ΔR between the active spacecraft and the target satellite st =R t -R s , relative distance ΔR=|R t -R s |.

[0093] (2) Azimuth angle and azimuth angular velocity, pitch angle and pitch angular velocity

[0094] The azimuth and pitch angles generally refer to the azimuth and pitch of the target satellite relative to the active spacecraft in the VVLH coordinate system. The relative position vector calculated above is expressed in the J2000 coordinate system. In order to obtain the azimuth and pitch in the VVLH system, it is necessary to convert ΔR stThe vector is converted to the satellite VVLH coordinate system using the following formula:

[0095]

[0096] In the formula, i s ,Ω s ,u s They are the orbital inclination, right ascension of ascending node and argument of latitude of active spacecraft respectively.

[0097] The calculation formula of azimuth angle and azimuth angular velocity is as follows: where θ_temp is the process variable for calculating azimuth angle, θ is the azimuth angle, is the azimuth angular velocity.

[0098]

[0099] The calculation formula of pitch angle and pitch angle angular velocity is as follows: is the pitch angle, is the pitch angle velocity.

[0100]

[0101] (3) Sun angle

[0102] The solar angle is defined as the angle between the target satellite pointing to the active spacecraft vector and the target satellite pointing to the sun vector. i is the solar vector in the inertial system. ΔR st is the relative position vector between the active spacecraft and the target satellite. α refers to the solar angle.

[0103]

[0104] (4) Geo-atmospheric angle

[0105] The Earth-Air Angle is the angle between the Earth-Air Light and the Earth-Air Light, which refers to the angle between the active spacecraft's vector pointing to the Earth's center and the active spacecraft's vector pointing to the target satellite. st is the relative position vector between the active spacecraft and the target, R s is the position vector of the active spacecraft in the J2000 system, and β refers to the Earth-atmosphere angle.

[0106]

[0107] Generally, the constraints for active spacecraft to approach and image the target satellite are as follows: the imaging distance is less than the maximum imaging distance constraint of the payload, the azimuth and pitch angles are within the maximum working angle range of the spacecraft rotation mechanism, and the sun angle and earth angle meet the minimum imaging angle constraint. The specific screening method is as follows.

[0108]

[0109] In the formula, R max is the maximum relative distance between the active spacecraft and the target satellite;

[0110] θ min ,θ max are the minimum and maximum values ​​of the azimuth, respectively. The azimuth refers to the position of the target satellite relative to the active spacecraft in the VVLH coordinate system;

[0111] are the minimum and maximum values ​​of the pitch angle, respectively. The pitch angle refers to the pitch of the target satellite relative to the active spacecraft in the VVLH coordinate system;

[0112] are the minimum and maximum azimuth angular velocity, respectively.

[0113] are the minimum and maximum values ​​of the pitch angle velocity, respectively.

[0114] α min is the minimum value of the solar angle, which is defined as the angle between the target satellite pointing to the active spacecraft vector and the target satellite pointing to the sun vector.

[0115] β min It is the minimum value of the Earth-atmosphere angle. The Earth-atmosphere angle is the angle between the Earth-atmosphere light and the Earth-atmosphere light. It refers to the angle between the active spacecraft’s vector pointing to the center of the earth and the active spacecraft’s vector pointing to the target satellite.

[0116] If there is a solution that satisfies the above conditions, the set of intersection point parameters (Δh, Δf) is considered to meet the imaging conditions and is stored in the feasible solution matrix [(Δh i ,Δf i )]middle.

[0117] Step 3: Solve for the optimal intersection point parameters

[0118] Considering the influence of spatial perturbation on the final imaging effect, the intersection point parameters should choose the feasible solution matrix [(Δh i ,Δf i )], that is, the more feasible solutions around the selected (Δh, Δf), the better. The steps of solving the optimal (Δh, Δf) using the mean shift algorithm in the clustering algorithm are as follows.

[0119] (1) In the feasible solution matrix [(Δh i ,Δf i )] randomly select a group as the center (Δh0, Δf0);

[0120] (2) Given a search radius r, find all points whose distance from (Δh0, Δf0) is less than r, recorded as set M, and consider these points to belong to category c. At the same time, the number of visits to these points in category c is increased by 1;

[0121] (3) Taking (Δh0, Δf0) as the center point, calculate the vector from (Δh0, Δf0) to each element in the set M, and add these vectors to obtain the drift M. r ;

[0122] (4) Update the center point (Δh0, Δf0) = (Δh0, Δf0) + M r , indicating that (Δh0, Δf0) is along the direction M r Moved distance ||M r ||;

[0123] (5) Repeat steps (2) to (4) until ||M r || is less than the set threshold, stop the iteration, remember (Δh0, Δf0) at this time, all points in this iteration process belong to category c;

[0124] (6) If the center of the current category c and the center of the existing category c′ are less than the threshold during convergence, then the current c should belong to the same category as c′ and be merged into c′; otherwise, c is treated as a new category and an additional category is added;

[0125] (7) Repeat (2) to (4) until all points are marked as visited;

[0126] (8) Classification: Find the category with the most visits for each point and assign it to that category;

[0127] (9) The center of the class with the largest number of points is the optimal intersection parameter.

[0128] In order to make the physical laws and effects described in this patent easier to understand, this patent is further described below in conjunction with specific embodiments.

[0129] 1. Task Design Constraints

[0130] This patent aims to design the optimal intersection point parameters for the imaging task of spatial heterogeneous targets. The specific constraints of the task design are as follows.

[0131] (1) The orbital parameters of the active spacecraft and the target satellite are shown in Table 1.

[0132] Table 1

[0133]

[0134]

[0135] (2) The spacecraft payload operating constraints are shown in Table 2.

[0136] Table 2

[0137] Constraints Constraint Value Minimum rendezvous time for imaging 1s The maximum intersection distance that can be imaged 150km Minimum sun angle 60° Turntable azimuth range -120°～120° Turntable pitch angle range -12°～65° Turntable azimuth angular velocity range -8°～8° Turntable pitch angle angular velocity range -8°～8° Minimum ground light angle 12°

[0138] (3) Imaging task requirements

[0139] The spacecraft's closest imaging distance to the target is less than 30km, and the safety distance is 5km. During the imaging mission, the spacecraft's attitude is oriented toward the sun.

[0140] 2. Calculation of Rendezvous Parameters to Meet Mission Requirements

[0141] Assume that the height difference and phase difference between the intersection point and the target satellite range from -20000m to 20000m and -0.2° to 0.2° respectively, and the search step length is 1000m and 0.01° respectively. According to steps 1 and 2, there are 294 sets of rendezvous parameters that meet the above mission requirements. Figure 2 shown.

[0142] 3. Solving the optimal intersection point parameters

[0143] First, the 294 feasible intersection parameters are normalized, the search radius is set to 0.07, and the mean shift algorithm is used to solve the process and the optimal intersection parameters. Figure 3 and Figure 4 As can be seen from the figure, the optimal intersection point parameter ([-7500, 0.02]) obtained by screening has the most feasible solutions clustered around it, which meets the task requirements.

[0144] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for obtaining the optimal intersection point of spatial non-planar target intersection imaging, characterized in that: According to the requirements of the space rendezvous imaging mission, considering the active spacecraft attitude and payload constraints, all intersection point parameters that meet the conditions are given, and the optimal intersection point parameters are screened out based on the clustering algorithm; the intersection point parameters are defined as the height difference and phase difference between the active spacecraft and the target satellite at the intersection point; The specific steps are as follows: Step 1: According to the requirements of the space rendezvous imaging mission, the altitude difference and phase difference search range between the active spacecraft and the target satellite at the intersection point is set, and the position and velocity of the active spacecraft and the target satellite at the intersection point are calculated according to the orbital parameters of the active spacecraft and the target satellite; Step 2: According to the relative positions of the active spacecraft and the target satellite at the intersection point, considering the active spacecraft attitude and payload working constraints, it is determined whether the intersection point parameters can meet the mission requirements. If they meet the mission requirements, the intersection point parameters are considered feasible and stored in the feasible solution matrix. Step 2 is as follows: The constraints for the active spacecraft to approach and image the target satellite are as follows: the imaging distance is less than the maximum imaging distance constraint of the payload, the azimuth angle and the pitch angle are within the maximum working angle range of the spacecraft rotation mechanism, and the sun angle and the earth angle meet the minimum imaging angle constraint; The specific screening method is as follows: In the formula, R max is the maximum relative distance between the active spacecraft and the target satellite; θ min ,θ max are the minimum and maximum values ​​of the azimuth, respectively. The azimuth refers to the position of the target satellite relative to the active spacecraft in the VVLH coordinate system; are the minimum and maximum values ​​of the pitch angle, respectively. The pitch angle refers to the pitch of the target satellite relative to the active spacecraft in the VVLH coordinate system; are the minimum and maximum values ​​of the azimuth angular velocity respectively; are the minimum and maximum values ​​of the pitch angle velocity respectively; α min is the minimum value of the solar angle, which is defined as the angle between the target satellite pointing to the active spacecraft vector and the target satellite pointing to the sun vector; β min is the minimum value of the Earth-atmosphere angle. The Earth-atmosphere angle is the angle between the Earth-atmosphere light and refers to the angle between the active spacecraft’s vector pointing to the center of the Earth and the active spacecraft’s vector pointing to the target satellite. If there is a solution that satisfies the above conditions, the intersection point parameters (Δh, Δf) are considered to meet the imaging conditions and are stored in the feasible solution matrix [(Δh i ,Δf i )]middle; Step 3: Considering the influence of perturbation iteration on the final intersection accuracy, a clustering algorithm is used to obtain the optimal intersection point parameters for all feasible solutions of the intersection point parameters.

2. The method for obtaining the optimal intersection point of spatial non-planar target intersection imaging according to claim 1, characterized in that: Step 1 is as follows: Assuming that the height difference and phase difference between the active spacecraft and the target satellite at the intersection point are (Δh, Δf), the position and velocity of the active spacecraft and the target satellite at the intersection point are calculated as follows: (a) Determine the latitude argument of the intersection point between the active spacecraft and the target satellite; According to the adjacent four-element formula of the spherical triangle, we get: In the formula, u sc is the latitude argument of the rendezvous point of the active spacecraft, u tc is the latitude argument of the intersection point of the target satellite, Ω s is the right ascension of the ascending node of the active spacecraft, Ω t is the right ascension of the target satellite ascending node, i s is the active spacecraft inclination angle, i t is the target satellite inclination; (b) Determine the rate of change of latitude argument of the active spacecraft and the target satellite; In the formula, u s is the latitude argument of the active spacecraft, u t is the latitude argument of the target satellite, r s is the distance from the center of the Earth to the active spacecraft, r t are the geocentric distances of the target satellites respectively; (c) Determine the latitude arguments before and after the intersection point; In the formula, u sc is the latitude argument of the active spacecraft at the rendezvous point, u tc is the latitude argument of the target satellite at the intersection point, Δf is the true anomaly difference between the active spacecraft and the target satellite at the intersection point, Δt is the running time, and u s0 is the latitude argument at the start time of active spacecraft calculation, u t0 The latitude argument at the start time calculated for the target satellite, u sf is the latitude argument at the terminal moment calculated by the active spacecraft, u tf The latitude argument at the terminal time calculated for the target satellite; (d) The target orbital radius vector of the known intersection point is r t , r s =r t +Δh, from which the position and velocity of the active spacecraft near the intersection point are obtained; R sx =r s (cosΩ s something s -sinΩ s so s sinus s ) R sy =r s (sinΩ s something s +cosΩ s so s sinus s ) R sz =r s (breasts) s sinus s ) In the formula, R sx is the X-direction position of the active spacecraft J2000, R sy is the Y-direction position of the active spacecraft J2000, R sz is the Z-direction position of the active spacecraft J2000, V sx is the velocity in the X direction of the active spacecraft J2000 system, V sy is the velocity of the active spacecraft J2000 in the Y direction, V sz is the velocity in the Z direction of the active spacecraft J2000 system; Similarly, the position and velocity of the target satellite near the rendezvous point can be obtained: RV t =[R tx , R ty , R tz , V tx , V ty , V tz ], R tx is the X-direction position of the target J2000 system, R ty is the Y-direction position of the target J2000 system, R tz is the Z-direction position of the target J2000 system, V tx is the velocity of the target satellite in the X direction in the J2000 system, V ty is the velocity of the target satellite in the Y direction in the J2000 system, V tz is the speed of the target satellite in the Z direction in the J2000 system.

3. The method for obtaining the optimal intersection point of spatial non-planar target intersection imaging according to claim 1, characterized in that: Step 3 is as follows: Considering the influence of spatial perturbation on the final imaging effect, the intersection point parameters should choose a feasible solution matrix [(Δh i ,Δf i )], that is, the more feasible solutions around the selected (Δh, Δf), the better.

4. The method for obtaining the optimal intersection point of spatial non-planar target intersection imaging according to claim 3, characterized in that: The steps for solving the optimal (Δh, Δf) using the mean shift algorithm in the clustering algorithm are as follows: (1) In the feasible solution matrix [(Δh i ,Δf i )] randomly select a group as the center (Δh0, Δf0); (2) Given a search radius r, find all points whose distance from (Δh0, Δf0) is less than r, recorded as set M, and consider these points to belong to category c. At the same time, the number of visits to these points in category c is increased by 1; (3) Taking (Δh0, Δf0) as the center point, calculate the vector from (Δh0, Δf0) to each element in the set M, and add these vectors to obtain the drift M. r ; (4) Update the center point (Δh0, Δf0) = (Δh0, Δf0) + M r , indicating that (Δh0, Δf0) is along the direction M r Moved distance ||M r ||; (5) Repeat steps (2) to (4) until ||M r || is less than the set threshold, stop the iteration, remember (Δh0, Δf0) at this time, all points in this iteration process belong to category c; (6) If the center of the current category c and the center of the existing category c′ are less than the threshold during convergence, then the current c should belong to the same category as c′ and be merged into c′; otherwise, c is treated as a new category and an additional category is added; (7) Repeat (2) to (4) until all points are marked as visited; (8) Classification: Find the category with the most visits for each point and assign it to that category; (9) The center of the class with the largest number of points is the optimal intersection parameter.

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