Target orbit forecasting and imaging window forecasting method based on CW equation
Through the CW equation method, the problem of target orbit forecasting and imaging window prediction when the satellite is not equipped with a measurement mechanism is solved, and high-precision and high-real-time orbit forecasting and imaging window prediction are achieved, supporting the formulation of orbit game strategies.
Patent Information
- Application Number
- CN202411593110.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-03-11
AI Technical Summary
The prior art is difficult to predict target orbits and predict imaging windows when the satellite is not equipped with corresponding measurement mechanisms, resulting in the inability to formulate an effective orbital game strategy.
Using a method based on CW equation, the relative position and velocity of the future target star are recursively obtained by relative navigation output, and the relative distance and light angle are calculated, thereby predicting the imaging window duration.
The autonomous orbit forecast and imaging window prediction of the target star are achieved, the prediction accuracy and real-time nature of the prior information are improved, and the consumption of manpower and time resources is reduced.
Smart Images
Figure CN119596349A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a target orbit prediction and imaging window prediction method based on a CW equation, and relates to the technical field of satellite guidance, navigation and control. Background Art
[0002] In the prior art, the prediction of target orbit and imaging window requires the participation of on-board measurement devices and the acquisition of measurement results. If the satellite is not equipped with the corresponding measurement device, or if direct measurement results cannot be obtained on the satellite, the target orbit prediction and imaging window prediction cannot be performed. In the target orbit game process, it is necessary to obtain prior information such as the position and velocity information of the target satellite in the future, the imaging window, etc., in order to formulate the corresponding game strategy and complete the specific orbit game task. Summary of the invention
[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and solve the problems of target orbit prediction and imaging window prediction.
[0004] The purpose of the present invention is achieved through the following technical solutions:
[0005] A target orbit prediction and imaging window prediction method based on CW equation, comprising:
[0006] Step 1: Based on the relative position and velocity output by relative navigation, the relative position and velocity of the target star in the second orbital coordinate system of the primary star within the required time in the future can be recursively obtained by using the CW equation.
[0007] When entering the algorithm, the relative position and velocity of the target star output by relative navigation in the second orbital coordinate system of the host star are X0 = [x0, y0, z0] T and According to the analytical solution of the CW equation, the relative position and velocity of the target star in the second orbital coordinate system of the host star at any time t can be obtained as follows:
[0008]
[0009]
[0010]
[0011]
[0012]
[0013]
[0014] Where n is the orbital angular velocity of the main star, X0 = [x0, y0, z0] T and is the initial relative position and velocity at the time of entering the algorithm, which is output by relative navigation, where x0, y0, z0 are the three-axis components of X0, are the three-axis components of V0.
[0015] Step 2: Calculate the relative distance and minimum relative distance between the target star and the main star at each moment in the future.
[0016] According to the distance calculation formula, the relative distance between the two stars at any time t can be obtained as follows:
[0017]
[0018] Then the minimum distance between the two stars in the future required time is
[0019] d min =min[d(t)]
[0020] Step 3: Calculate the illumination angle and minimum illumination angle of the target star and the main star at each moment in the future.
[0021] The definition of illumination angle is Figure 2 As shown, θ is the angle between the relative position vector of the target star in the second orbital coordinate system of the host star and the position vector of the sun in the second orbital coordinate system of the host star.
[0022] First, record the moment of entering the algorithm, the position vector R of the sun in the second orbital coordinate system of the primary star sun0 =[x sun0 ,y sun0 ,z sun0 ] T , where x sun0 ,y sun0 ,z sun0 For R sun0 The XYZ three-axis components of are the initial values of the angle between the sun vector and the z-axis of the second orbital system of the primary star at the time of entering the algorithm. The specific calculation method is as follows:
[0023] If sun0 >0 and x sun0 > 0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is
[0024]
[0025] If sun0 >0 and x sun0 <0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is
[0026]
[0027] If sun0<0 and x sun0 <0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is
[0028]
[0029] If sun0 <0 and x sun0 > 0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is
[0030]
[0031] Then calculate the predicted value of the angle between the sun vector and the z-axis of the second orbital coordinate system of the primary star at each moment in the future:
[0032]
[0033] Then, according to the recursive value of the CW equation, the predicted value of the angle β between the target satellite position vector and the z-axis of the second orbital coordinate system of the host satellite at each moment in the future is calculated. The specific calculation method is as follows:
[0034] If z(t)>0 and x(t)>0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is
[0035]
[0036] If z(t)>0 and x(t)<0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is
[0037]
[0038] If z(t) < 0 and x(t) < 0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is
[0039]
[0040] If z(t) < 0 and x(t) > 0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is
[0041]
[0042] Finally, the illumination angle of the two stars at each moment in the future required time is calculated as
[0043]
[0044] Then the minimum illumination angle of the two stars in the future required time is
[0045] γ min=min[γ(t)]
[0046] Step 4: Based on the predicted relative distance and illumination angle, calculate the required time for the imaging window of the target star to our star.
[0047] Define the imaging window valid flag SF as
[0048]
[0049] Among them, maxDistance is the farthest distance that the target star can be imaged, and maxSunlightAngle is the maximum illumination angle that the target star can be imaged.
[0050] The target effective imaging window time is
[0051]
[0052] Among them, T is the total prediction time.
[0053] A target orbit prediction and imaging window prediction device based on CW equation, comprising:
[0054] The first module, based on the relative position and relative velocity output by the relative navigation, recursively obtains the relative position and relative velocity of the target satellite in the second orbital coordinate system of the host satellite at each moment in the future based on the CW equation;
[0055] The second module is used to calculate the relative distance and minimum relative distance between the target star and the main star at each moment in the future;
[0056] The third module is used to calculate the illumination angle and minimum illumination angle of the target star and the main star at each moment in the future period of time;
[0057] The fourth module calculates the duration of the imaging window of the target star to our star in the future based on the predicted relative distance and illumination angle.
[0058] Compared with the prior art, the present invention has the following beneficial effects:
[0059] (1) The present invention predicts the relative position of the target through the CW equation and predicts the illumination angle through solar vector recursion, thereby realizing the orbit prediction of the target, the closest distance between two satellites, the minimum illumination angle, and the imaging window prediction, and providing information input for the subsequent judgment of the target's orbital intention and the formulation of orbital game guidance strategy.
[0060] (2) The present invention can completely predict the target's onboard autonomous orbit and imaging window, which can greatly reduce manpower and time resources compared to the method of relying on ground-based target orbit determination.
[0061] (3) The present invention has high prediction accuracy and strong real-time performance for target prior information. BRIEF DESCRIPTION OF THE DRAWINGS
[0062] Figure 1 The figure is a flow chart of the steps of the method of the present invention.
[0063] Figure 2 Define a graph for the sun's illumination angle. DETAILED DESCRIPTION
[0064] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.
[0065] A target orbit prediction and imaging window prediction method based on CW equations, using the relative position and velocity data output by relative navigation as the initial value, the satellite relies on CW equations to recursively obtain the relative position and velocity of the target satellite in the second orbital coordinate system of the main satellite within the required time in the future, and then calculates the distance and illumination angle of the two satellites within the required time in the future, and autonomously calculates the imaging window duration of the target satellite to the main satellite, the closest distance between the two satellites, and the minimum illumination angle within the required time in the future according to the distance and illumination angle constraints. The method of the present invention can autonomously calculate the relative orbit and imaging window of the target in the future, provide information input for the subsequent orbit game guidance strategy, and has strong engineering practicality.
[0066] like Figure 1 As shown, specifically including:
[0067] Step 1: Based on the relative position and velocity output by relative navigation, the relative position and velocity of the target star in the second orbital coordinate system of the primary star within the required time in the future can be recursively obtained by using the CW equation.
[0068] When entering the algorithm, the relative position and velocity of the target star output by relative navigation in the second orbital coordinate system of the host star are X0 = [x0, y0, z0] T and According to the analytical solution of the CW equation, the relative position and velocity of the target star in the second orbital coordinate system of the host star at any time t can be obtained as follows:
[0069]
[0070]
[0071]
[0072]
[0073]
[0074]
[0075] Where n is the orbital angular velocity of the main star, X0 = [x0, y0, z0] T and is the initial relative position and velocity at the time of entering the algorithm, which is output by relative navigation, where x0, y0, z0 are the three-axis components of X0, are the three-axis components of V0.
[0076] Step 2: Calculate the relative distance and minimum relative distance between the target star and the main star at each moment in the future.
[0077] According to the distance calculation formula, the relative distance between the two stars at any time t can be obtained as follows:
[0078]
[0079] Then the minimum distance between the two stars in the future required time is
[0080] d min =min[d(t)]
[0081] Step 3: Calculate the illumination angle and minimum illumination angle of the target star and the main star at each moment in the future.
[0082] The definition of illumination angle is Figure 2 As shown, θ is the angle between the relative position vector of the target star in the second orbital coordinate system of the host star and the position vector of the sun in the second orbital coordinate system of the host star.
[0083] First, record the moment of entering the algorithm, the position vector R of the sun in the second orbital coordinate system of the primary star sun0 =[x sun0 ,y sun0 ,z sun0 ] T , where x sun0 ,y sun0 ,z sun0 For R sun0 The XYZ three-axis components of are the initial values of the angle between the sun vector and the z-axis of the second orbital system of the primary star at the time of entering the algorithm. The specific calculation method is as follows:
[0084] If sun0 >0 and x sun0 > 0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is
[0085]
[0086] If sun0 >0 and x sun0 <0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is
[0087]
[0088] If sun0 <0 and x sun0 <0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is
[0089]
[0090] If sun0 <0 and x sun0 > 0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is
[0091]
[0092] Then calculate the predicted value of the angle between the sun vector and the z-axis of the second orbital coordinate system of the primary star at each moment in the future:
[0093]
[0094] Then, according to the recursive value of the CW equation, the predicted value of the angle β between the target satellite position vector and the z-axis of the second orbital coordinate system of the host satellite at each moment in the future is calculated. The specific calculation method is as follows:
[0095] If z(t)>0 and x(t)>0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is
[0096]
[0097] If z(t)>0 and x(t)<0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is
[0098]
[0099] If z(t) < 0 and x(t) < 0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is
[0100]
[0101] If z(t) < 0 and x(t) > 0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is
[0102]
[0103] Finally, the illumination angle of the two stars at each moment in the future required time is calculated as
[0104]
[0105] Then the minimum illumination angle of the two stars in the future required time is
[0106] γ min =min[γ(t)]
[0107] Step 4: Based on the predicted relative distance and illumination angle, calculate the required time for the imaging window of the target star to our star.
[0108] Define the imaging window valid flag SF as
[0109]
[0110] Among them, maxDistance is the farthest distance that the target star can be imaged, and maxSunlightAngle is the maximum illumination angle that the target star can be imaged.
[0111] The target effective imaging window time is
[0112]
[0113] Among them, T is the total prediction time.
[0114] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.
[0115] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.
Claims
1. A target orbit prediction and imaging window prediction method based on CW equation, characterized in that: include: Step 1: According to the relative position and relative velocity output by relative navigation, the relative position and relative velocity of the target satellite in the second orbital coordinate system of the host satellite at each moment in the future are recursively obtained based on the CW equation; Step 2: Calculate the relative distance and minimum relative distance between the target star and the main star at each moment in the future; Step 3: Calculate the illumination angle and minimum illumination angle of the target star and the main star at each moment in the future period of time; Step 4: Based on the predicted relative distance and illumination angle, calculate the duration of the imaging window of the target star to my star in the future.
2. The target orbit prediction and imaging window prediction method according to claim 1, characterized in that: In step 1, the relative position and velocity of the target star output by relative navigation in the second orbital coordinate system of the host star are respectively X0=[x0,y0,z0] T and According to the analytical solution of the CW equation, the relative position and velocity of the target star in the second orbital coordinate system of the host star at any time t are obtained as follows: Where n is the orbital angular velocity of the main star, X0 = [x0, y0, z0] T and is the initial relative position and velocity at the time of entering the algorithm, which is output by relative navigation, where x0, y0, z0 are the three-axis components of X0, are the three-axis components of V0.
3. The target orbit prediction and imaging window prediction method according to claim 2, characterized in that: In step 2, according to the distance calculation formula, the relative distance between the two stars at any time t can be obtained as Then the minimum distance between the two stars in the future required time is d min =min[d(t)]。 4. The target orbit prediction and imaging window prediction method according to claim 3, characterized in that: In step 3, first record the position vector R of the sun in the second orbital coordinate system of the primary star at the time of entering the algorithm sun0 =[x sun0 ,y sun0 ,z sun0 ] T , where x sun0 ,y sun0 ,z sun0 For R sun0 The XYZ three-axis components of are the initial values of the angle between the sun vector and the z-axis of the second orbital system of the primary star at the time of entering the algorithm. The specific calculation method is as follows: If sun0 >0 and x sun0 > 0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is If sun0 >0 and x sun0 <0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is If sun0 <0 and x sun0 <0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is If sun0 <0 and x sun0 > 0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is Then calculate the predicted value of the angle between the sun vector and the z-axis of the second orbital coordinate system of the primary star at each moment in the future: Then, according to the recursive value of the CW equation, the predicted value of the angle β between the target satellite position vector and the z-axis of the second orbital coordinate system of the host satellite at each moment in the future is calculated. The specific calculation method is as follows: If z(t)>0 and x(t)>0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is If z(t)>0 and x(t)<0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is If z(t) < 0 and x(t) < 0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is If z(t) < 0 and x(t) > 0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is Finally, the illumination angle of the two stars at each moment in the future required time is calculated as Then the minimum illumination angle of the two stars in the future required time is c min = min[γ(t)].
5. The target orbit prediction and imaging window prediction method according to claim 4, characterized in that: In step 4, the imaging window duration of the target star to our star is calculated based on the predicted relative distance and illumination angle; Define the imaging window valid flag SF as Among them, maxDistance is the farthest distance that the target star can be imaged, and maxSunlightAngle is the maximum illumination angle that the target star can be imaged; The target effective imaging window time is Among them, T is the total prediction time.
6. A target orbit prediction and imaging window prediction device based on CW equation, characterized in that: include: The first module, based on the relative position and relative velocity output by the relative navigation, recursively obtains the relative position and relative velocity of the target satellite in the second orbital coordinate system of the host satellite at each moment in the future based on the CW equation; The second module is used to calculate the relative distance and minimum relative distance between the target star and the main star at each moment in the future; The third module is used to calculate the illumination angle and minimum illumination angle of the target star and the main star at each moment in the future period of time; The fourth module calculates the duration of the imaging window of the target star to our star in the future based on the predicted relative distance and illumination angle.
7. The target orbit prediction and imaging window prediction method according to claim 6, characterized in that: In the first module, the relative position and velocity of the target star output by relative navigation in the second orbital coordinate system of the host star are respectively X0=[x0,y0,z0] T and According to the analytical solution of the CW equation, the relative position and velocity of the target star in the second orbital coordinate system of the host star at any time t are obtained as follows: Where n is the orbital angular velocity of the main star, X0 = [x0, y0, z0] T and is the initial relative position and velocity at the time of entering the algorithm, which is output by relative navigation, where x0, y0, z0 are the three-axis components of X0, are the three-axis components of V0.
8. The target orbit prediction and imaging window prediction device according to claim 7, characterized in that: In the second module, according to the distance calculation formula, the relative distance between the two stars at any time t can be obtained as Then the minimum distance between the two stars in the future required time is d min =min[d(t)]。 9. The target orbit prediction and imaging window prediction device according to claim 8, characterized in that: In the third module, we first record the position vector R of the sun in the second orbital coordinate system of the primary star at the time of entering the algorithm. sun0 =[x sun0 ,y sun0 ,z sun0 ] T , where x sun0 ,y sun0 ,z sun0 For R sun0 The XYZ three-axis components of are the initial values of the angle between the sun vector and the z-axis of the second orbital system of the primary star at the time of entering the algorithm. The specific calculation method is as follows: If sun0 >0 and x sun0 > 0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is If sun0 >0 and x sun0 <0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is If sun0 <0 and x sun0 <0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is If sun0 <0 and x sun0 > 0, then the initial value of the angle between the sun vector and the z-axis of the second orbital system of the primary star is Then calculate the predicted value of the angle between the sun vector and the z-axis of the second orbital coordinate system of the primary star at each moment in the future: Then, according to the recursive value of the CW equation, the predicted value of the angle β between the target satellite position vector and the z-axis of the second orbital coordinate system of the host satellite at each moment in the future is calculated. The specific calculation method is as follows: If z(t)>0 and x(t)>0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is If z(t)>0 and x(t)<0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is If z(t) < 0 and x(t) < 0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is If z(t) < 0 and x(t) > 0, the predicted value of the angle β between the target satellite position vector and the z-axis of the host satellite's second orbital coordinate system is Finally, the illumination angle of the two stars at each moment in the future required time is calculated as Then the minimum illumination angle of the two stars in the future required time is c min = min[γ(t)].
10. The target orbit prediction and imaging window prediction device according to claim 9, characterized in that: The fourth module calculates the imaging window duration of the target star to our star in the future according to the predicted relative distance and illumination angle; Define the imaging window valid flag SF as Among them, maxDistance is the farthest distance that the target star can be imaged, and maxSunlightAngle is the maximum illumination angle that the target star can be imaged; The target effective imaging window time is Among them, T is the total prediction time.