High-orbit space target enhanced detection method based on dynamic coordinate system gaze

Abstract

The application discloses a high-orbit space target enhanced detection method based on a moving coordinate system gaze, and belongs to the technical field of space-based space situation awareness. The method solves the problems of insufficient signal accumulation capacity, strong dependence on orbit priori and high system complexity in the process of detecting a small high-orbit space target. The method comprises the following steps: S1, defining an earth observation reference unit and constructing a virtual observation target; S2, calculating corresponding gaze directions according to the orbit position of an observation platform and the position of the virtual observation target, so as to construct an observation reference which moves synchronously with the earth reference system; S3, adjusting the XY axis direction of a load, so that the long side of an observation field is parallel to the equator, and finally obtaining an observation direction sequence; and S4, analyzing the gaze angular velocity, and ensuring that the gaze angular velocity is within the range of satellite attitude control.

Description

Technical Field

[0001] This invention belongs to the field of space-based situational awareness technology, specifically relating to an enhanced detection method for high-orbit space targets based on a staring motion coordinate system. Background Technology

[0002] Currently, space-based detection of high-orbit space targets mainly employs imaging methods based on inertial space reference frames and tracking and staring methods based on target orbit information. However, these methods still have significant shortcomings in practical applications and are difficult to meet the needs of detecting faint targets with low signal-to-noise ratios and conducting regional surveys.

[0003] First, when observing in an inertial space reference frame, the observation system typically uses an inertial coordinate system against the stellar background for stable pointing. In this mode, high-orbit space targets exhibit a certain apparent motion relative to the stellar background, resulting in continuous trajectories or tails on the detector during imaging. This causes the target signal to disperse in space, reducing the peak signal and significantly decreasing the signal-to-noise ratio. This problem is particularly pronounced for targets with low brightness or small size, severely limiting the system's detection sensitivity and recognition capabilities.

[0004] Secondly, the target-based tracking staring method, by adjusting the observation pointing in real time, keeps the target relatively stationary on the image plane. This method has certain advantages under known target conditions, but its performance is highly dependent on the accuracy of the target's orbit information. When there are errors in the orbit prediction or target maneuvers, the target may deviate from the field of view or the imaging position may be unstable, affecting the signal accumulation effect. In addition, this method requires detailed target orbit parameter input and orbit extrapolation calculation to achieve attitude pointing planning, resulting in high system complexity.

[0005] Furthermore, under space-based observation conditions, the position and attitude of the observation platform are constantly changing over time due to its orbital motion, making the observation geometry more complex. This poses challenges to existing methods in terms of stable signal accumulation, observation pointing, and system implementation.

[0006] In summary, existing technologies for detecting small, high-orbit space targets suffer from problems such as insufficient signal accumulation capabilities, strong reliance on prior orbital information, and high system complexity, and require further improvement. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides an enhanced detection method for high-orbit space targets based on a dynamic coordinate system gaze model. This invention aims to address the difficulty of directly establishing a stable observation pointing relationship with the Earth reference frame under on-orbit operation conditions of space-based platforms. It proposes an observation planning method that constructs a virtual observation target based on geographic coordinates and reconstructs the space-based observation reference frame by building a dynamic coordinate system. This method enables space-based observation platforms to achieve stable gaze observation of Earth reference areas without relying on prior information about specific target orbits, thereby supporting continuous observation and regional surveys of high-orbit space targets.

[0008] The method specifically includes the following steps: S1. Define the Earth observation reference unit and construct the virtual observation target; S2. Calculate the corresponding gaze direction based on the orbital position of the observation platform and the position of the virtual observation target, thereby constructing an observation reference that moves synchronously with the Earth reference system; S3. Adjust the XY axis orientation of the load so that the long side of the observation field of view is parallel to the equator, and finally obtain the observation orientation sequence; S4. Analyze the freezing angle velocity to ensure it is within the satellite attitude control range.

[0009] Furthermore, let the latitude, longitude, and altitude of the virtual observation target be... ,in Indicates longitude. Indicates latitude, The virtual observation target's position vector, representing altitude, is as follows:

[0010] in, For the Earth's eccentricity, The radius of curvature of the circle is denoted as . This is the Earth's semi-major axis.

[0011] Furthermore, the calculation process for the gaze direction is as follows:

[0012] in, As the direction of the gaze, For the Euler angles in the Euler axis-angle transformation from the orbital frame to the gaze direction, For the Euler axis in the orbital system.

[0013] further, , in, , Let be the vector pointing from the Earth's center to the virtual observation target. Pay attention to quadrant determination when solving. This is the satellite position vector.

[0014] further, , in, , , , This is the satellite's WGS84 velocity vector.

[0015] Furthermore, the calculation process for the observed pointing sequence is as follows: , in, To represent quaternion multiplication, Let be the rotational quaternion about the Z-axis of the star. It is an inertial quaternion.

[0016] further, ,in, , Earth axis vector The angle between the projection of the star onto the XOY plane and the X-axis of the star.

[0017] further, , It is the quaternion for the conversion between the orbital frame and the inertial frame.

[0018] The beneficial effects of the method described in this invention are as follows: (1) Observation planning can be carried out without relying on the precise orbit information of the target, which reduces the system's dependence on the accuracy of orbit prediction and the integrity of the target database; (2) It can directly conduct staring observations on geographic reference areas, taking into account both target enhancement detection and regional survey needs, breaking through the limitations of traditional target-driven observation modes; (3) By constructing a dynamic coordinate system, the relative motion velocity of the high-orbit target in the observation reference system is significantly reduced, thereby improving the target signal accumulation capability and detection sensitivity; (4) Make the stellar background form a trailing distribution on the image plane, reduce the influence of the stellar background on the detection of weak targets, and improve the detection probability of dark and weak targets; (5) Under the condition of sun-synchronous orbit, by selecting high-latitude regions for observation, the required freezing point velocity can be effectively reduced and the observation duration can be increased. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the vector relationship between the geocenter, the satellite platform S, and the virtual observation target in an embodiment of the present invention; Figure 2 This is a schematic diagram of the observation results in the inertial space reference frame in an embodiment of the present invention; Figure 3 This is a schematic diagram of the observation results using a gaze in a moving coordinate system in an embodiment of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0021] Example 1 Step 1: Define the Earth observation reference unit and construct the virtual observation target. Within the Earth reference frame, an observation area is selected, and its latitude, longitude, and altitude information are defined as a fixed Earth observation reference unit. A binding relationship is established between this reference unit and the Earth rotation model to characterize the Earth reference benchmark for space-based observations. Let the latitude, longitude, and altitude of the virtual observation target be... ,in Indicates longitude. Indicates latitude, The virtual observation target's position vector, representing altitude, is as follows: (1) in, For the Earth's eccentricity, The radius of curvature of the circle is denoted as . This is the Earth's semi-major axis.

[0022] By using the above method, discrete Earth regions are uniformly mapped into continuous spatial observation reference units, providing a foundation for subsequent time evolution modeling.

[0023] Step 2: Inertial space evolution modeling of the observation reference unit To achieve continuous observation of a fixed reference unit under Earth's reference, it is necessary to establish the spatial geometric relationship between the space-based observation platform and the virtual target. Since the constructed virtual observation target maintains a fixed correspondence with the Earth's reference frame, its position in inertial space changes continuously with the Earth's rotation. Therefore, it is necessary to calculate the corresponding gaze direction based on the orbital position of the observation platform and the position of the virtual observation target, thereby constructing an observation reference that moves synchronously with the Earth's reference frame.

[0024] First, based on the WGS84 position information of the space-based observation platform, the staring direction is calculated in the orbital coordinate system. For example... Figure 1 The image shows the geocentric O and the satellite platform. and virtual observation targets Vector relationships: Depend on Figure 1 It can be known that: (2) (3) in For the Euler angles in the Euler axis-angle transformation from the orbital frame to the gaze direction, For geocentric satellite platforms Direction and geocentric pointing towards virtual observation target The angle between directions, Let be the vector pointing from the Earth's center to the virtual observation target. Pay attention to quadrant determination when solving. This is the satellite position vector.

[0025] Euler axes are described in the WGS84 series as follows: (4) because With satellite position vector Perpendicular to each other, therefore At the same time, it lies within the XOY plane of the orbital system, requiring only the solution... The Euler axis in the orbital system can be determined by using the cosine values ​​of the X and Y axes of the orbital system.

[0026] The satellite's velocity vector in the instantaneous inertial frame is: (5) in, The WGS84 velocity vector of the satellite. For the entrainment velocity vector, This is the Earth's rotational angular velocity.

[0027] The Y-axis vector of the orbital system in the instantaneous inertial frame can then be expressed as: (6) The X-axis vector of the orbital system is given by the right-hand rule: (7) The Euler axis in the orbital system is: (8) Then the direction of the gaze in the orbital system is: (9) Then the gaze is directed through the quaternion of the conversion between the orbital and inertial frames. Realizing evolutionary modeling of inertial space: (10) in, Represents an inertial quaternion.

[0028] Through the above process, the virtual observation target defined in the Earth reference frame can be converted into a feasible inertial space observation target for the space-based platform, thus achieving the unification between the Earth fixed reference and the space-based moving reference.

[0029] Step 3: Adjust the XY axis orientation of the load so that the longer side of the observation field of view is parallel to the equator, thus obtaining the final observation orientation sequence. To further improve the coverage efficiency of the observation area and the target signal accumulation effect, it is necessary to optimize the configuration of the payload's field of view. Considering that high-orbit targets are mainly distributed near geostationary orbit, by constraining the long side of the field of view to be consistent with the equatorial direction, a larger orbital coverage range can be obtained while ensuring staring ability.

[0030] According to inertial quaternions Give direction cosine array Solve for the Earth axis vector The angle between the projection of the celestial body onto the XOY plane and the celestial body's X-axis. : (11) Obtain the rotation quaternion around the star's Z-axis: (12) in

[0031] The final observation sequence is as follows: (13) This represents quaternion multiplication and is a standard symbol in quaternion operations.

[0032] Step four: Analyze the freezing angle velocity to ensure it is within the satellite's attitude control range, and simultaneously provide imaging expectations. By adjusting the height parameter of the virtual observation target This allows for the planning of observations in space regions at different orbital altitudes. For example, when the virtual observation target altitude is set near the geostationary orbit altitude, enhanced detection of targets in the GEO region can be achieved; when adjusted to a higher or lower altitude, observation coverage of the corresponding space region can be achieved.

[0033] After obtaining the observation pointing sequence, it is necessary to further analyze the changes in the angular velocity of the observation pointing during the staring process to verify whether it meets the attitude control capability constraints of the space-based platform. If the staring angle velocity exceeds the platform's allowable range, the observation area should be reselected or the observation time window adjusted.

[0034] For sun-synchronous orbit observation platforms, since the relative velocity of the orbit to the Earth's reference frame is relatively small when passing through high-latitude regions, staring observations are preferably conducted in high-latitude areas. At this latitude, the rate of change in the observation point is low, which helps to extend the stable integration time and improve the accumulation of signals from weak targets.

[0035] Furthermore, in practical applications, conditions such as illumination constraints, Earth occlusion constraints, and payload operational constraints can be introduced to optimize the selection of observation areas and observation time windows. Among them, illumination constraints ensure that the target is under observable illumination conditions, while occlusion constraints prevent the target from being blocked by the Earth itself, thereby further improving the detection success rate and observation efficiency.

[0036] Example 2 This embodiment further defines Embodiment 1, applying the method from Embodiment 1 to a specific instance. It was implemented on a certain type of satellite, and the observation results are as follows: Figure 2-3 As shown.

[0037] As can be seen from the figure, the observation results using the inertial space reference frame result in signal energy being dispersed across multiple pixels due to the relative motion between the platform and the target, leading to a low peak signal-to-noise ratio. This is especially true for targets with weak reflectivity or small size, where the signal is easily submerged in background noise, making effective monitoring and identification difficult. In contrast, using a moving coordinate system for staring can significantly improve the target signal strength and signal-to-noise ratio, enhancing the detectability of small targets.

Claims

1. A method for enhancing the detection of high-orbit space targets based on staring in a moving coordinate system, characterized in that, The method includes the following steps: S1. Define the Earth observation reference unit and construct virtual observation targets; S2. Calculate the corresponding gaze direction based on the orbital position of the observation platform and the position of the virtual observation target, thereby constructing an observation reference that moves synchronously with the Earth reference system; S3. Adjust the XY axis orientation of the load so that the long side of the observation field of view is parallel to the equator, and finally obtain the observation orientation sequence; S4. Analyze the freezing angle velocity to ensure it is within the satellite attitude control range.

2. The high-orbit space target enhancement detection method based on dynamic coordinate system staring according to claim 1, characterized in that, Let the latitude, longitude, and altitude of the virtual observation target be... ,in Indicates longitude. Indicates latitude, The virtual observation target's position vector, representing altitude, is as follows: in, For the Earth's eccentricity, Let be the radius of curvature of the circle. This is the Earth's semi-major axis.

3. The high-orbit space target enhancement detection method based on dynamic coordinate system staring according to claim 2, characterized in that, The calculation process for the gaze direction is as follows: in, As the direction of the gaze, For the Euler angles in the Euler axis-angle transformation from the orbital frame to the gaze direction, For the Euler axis in the orbital system.

4. The high-orbit space target enhancement detection method based on dynamic coordinate system staring according to claim 3, characterized in that, ， in, , Let be the vector pointing from the Earth's center to the virtual observation target. Pay attention to quadrant determination when solving. This is the satellite position vector.

5. The high-orbit space target enhancement detection method based on dynamic coordinate system staring according to claim 4, characterized in that, ， in, , , , This is the satellite's WGS84 velocity vector.

6. The high-orbit space target enhancement detection method based on dynamic coordinate system staring according to claim 5, characterized in that, The calculation process for the observed pointing sequence is as follows: , in, To represent quaternion multiplication, Let be the rotational quaternion about the Z-axis of the star. It is an inertial quaternion.

7. The high-orbit space target enhancement detection method based on dynamic coordinate system staring according to claim 6, characterized in that, ,in, , Earth axis vector The angle between the projection of the star onto the XOY plane and the X-axis of the star.

8. The method for enhancing the detection of high-orbit space targets based on staring in a moving coordinate system according to claim 7, characterized in that, , It is the quaternion for the conversion between orbital and inertial frames.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-8.

10. A computer-readable storage medium for storing computer instructions, characterized in that, When the computer instructions are executed by the processor, they implement the steps of the method according to any one of claims 1-8.

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