Ground simulation method for space debris visible light detector identification data

Abstract

The invention provides a space debris visible light detector identification data ground simulation method. The method comprises the following steps: establishing a space debris target detectable energy model according to a detection distance, a detection phase angle, an equivalent reflection area and the like; according to the real-time position of the detector track, large-step screening is carried out on the visibility of the space debris target; and performing real-time detection result generation on the space debris target according to a large-step screening result. According to the scheme, real-time simulation of massive space debris identification data is realized through a hierarchical combination method of large-step screening, small-step simulation and real-time calculation of a detection result, and the ground simulation cost is reduced.

Description

Technical Field

[0001] The invention belongs to the field of space debris identification, and in particular relates to a ground simulation method for space debris identification data by a visible light detector. Background Art

[0002] The size of space debris can usually be divided into three levels: less than 1cm, 1cm-10cm and larger than 10cm. Space debris smaller than 1cm can be passively protected by installing protective structures. The ground can track, classify, monitor and warn of space debris larger than 10cm, and usually protect spacecraft through active avoidance methods. At present, it is difficult to orient, monitor and warn space debris of 1cm-10cm on the ground, and there is a lack of reasonable protection measures, which seriously affects the safety of human space activities. Therefore, space debris of 1cm-10cm is identified by the international community as the most dangerous spacecraft debris. At present, there are more than 500,000 pieces of space debris larger than 1cm, and more than 130 million objects larger than 1mm.

[0003] In orbit, visible light detectors can be used to initially capture and track space debris near the orbit. In ground test simulations, it is necessary to simulate the space debris that appears in the field of view of the visible light detector and the target data identified. Visible light detectors image debris through visible light observations. Space debris in the Earth's orbit is mainly detectable through reflection of sunlight. The simulation of visible light detector identification data for space debris has the following technical difficulties:

[0004] 1. In order to achieve 1:1 equivalent semi-physical simulation with on-board products, the simulation system needs to use a real-time system to realize data simulation and interaction with the on-board. The control cycle of the simulation system is generally on the order of 10ms, but the number of space debris larger than 1cm is estimated to exceed 500,000. The number of space targets announced by the foreign space monitoring network (Space-Track.ORG) is 44,500 (as of November 10, 2023). That is, at least 44,500 targets need to be simulated and traversed in orbit in each control cycle. The large amount of calculation cannot be achieved in a short time by the real-time system;

[0005] 2. There are targets at different distances in the field of view of the visible light detector. The imaging effect of the target on the visible light detector is affected by internal factors such as the detector's dynamic performance, target recognition sensitivity, and residence time in the field of view, as well as external factors such as the target's sunlight exposure angle, relative distance, reflectivity, and target size. It is a complex simulation system. Summary of the invention

[0006] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and provide a ground simulation method for space debris visible light detector identification data, so as to realize the complex calculation function of ground simulation by hierarchical combination of low-cost modules.

[0007] The technical solution of the present invention is: a ground simulation method for space debris visible light detector identification data, comprising:

[0008] Establishing a target detectable energy model for space debris;

[0009] Receive the current satellite time SatT, current orbital position SatR and velocity SatV of the probe spacecraft sent by the test host in real time, select the space debris target set SelectTargetData that meets the detectable constraints from the space debris target library and send it to the test host;

[0010] The test host performs periodic simulation on the received space debris target set SelectTargetData, calculates the detector's recognition data of space debris targets in real time, and completes the simulation of the detector's recognition data of space targets.

[0011] The method of establishing a target detectable energy model of space debris comprises:

[0012] Space debris generates energy by reflecting sunlight in space. Optical sensors detect space debris by sensing the reflected energy of debris. The detected energy is equivalent to the magnitude of the star, which is related to the detection distance, debris albedo and phase angle. The target detectable energy model is as follows:

[0013]

[0014] in:

[0015] m V is the target equivalent apparent magnitude, the smaller the value, the higher the brightness;

[0016] m SUN is the solar equivalent apparent magnitude;

[0017] A is the equivalent reflection area;

[0018] ρ is the target reflectivity;

[0019] is the phase angle;

[0020] is the attenuation function of the brightness of the target reflected light as the observation direction and the sunlight irradiation direction are different;

[0021] r is the distance between the target and the detector;

[0022] C1, C2 are constant coefficients.

[0023] The step of selecting a space debris target set SelectTargetData that meets the detectable constraint from the space debris target library includes:

[0024] Assume that the bound space debris target library is

[0025]

[0026] Where i = 1, 2, ..., N1, N1 is the number of space debris target libraries; TLE is the number of two-row orbital elements of space debris target i;

[0027] Orbit screening is performed according to period T, and the orbits of all space debris targets are extrapolated using the SGP4 / SDP4 model. The orbit extrapolation time t = SatT, SatT+T, SatT+2T is calculated to obtain ALLTargetData of each space debris target. i Position TargetR in J2000 inertial system i _t, speed TargetV i _t, and calculate the target ALLTargetData of each space debris i Vector Sun2Target with space debris pointing to the sun i ;

[0028] The orbit extrapolation method under the J2 perturbation model is used to extrapolate the orbit of the probe. The orbit extrapolation time t = SatT, SatT+T, SatT+2T, and the position SatR_t and velocity SatV_t of the probe in the J2000 inertial system are calculated;

[0029] The target vector Sat2TargetR of the detector pointing to the space debris is calculated i _t=TargetR i _t-SatR_t, further derive the space debris target ALLTargetData i The detection distance r from the detector at time t i _t=|Sat2TargetR i _t|;

[0030] Calculate the space debris target ALLTargetData i The phase angle with the detector at time t

[0031] The detection distance r i _t and phase angle Substitute the target detectable energy model of space debris to obtain the space debris target ALLTargetDatai The detectable energy m at the detector position at time i vi _t;

[0032] Calculate the space debris target ALLTargetData i The relative velocity of the detector at time i is Sat2TargetV i _t=TargetV i _t-SatV_t, and calculate the relative angular velocity ω i _t;

[0033] For all time t, all space debris targets ALLTargetData i Perform conditional screening; send the space debris target set SelectTargetData that meets the screening conditions to the test host.

[0034] The period T=the shortest task execution time of the entire satellite / 2.

[0035] The space debris target ALLTargetData i The phase angle with the detector at time t

[0036] The relative angular velocity

[0037]

[0038] For all time t, all space debris targets ALLTargetData i Perform conditional screening, the screening conditions are:

[0039] 1)m vi _t≤m max

[0040] 2)ω i _t≤ω max

[0041] Among them, m max Indicates the maximum sensitivity of the visible light detector, ω max Indicates that the visible light detector recognizes the maximum relative angular velocity; satisfying the above two conditions at the same time means that the screening conditions are met.

[0042] The test host periodically simulates the received space debris target set SelectTargetData, and calculates the space debris target identification data of the detector in real time, including:

[0043] Use SGP4 / SDP4 model to select target data of space debrisj Extrapolate the orbits of all targets in j = 1, 2, ..., N2, where N2 is the number of space targets after screening; calculate the position of each target in the J2000 inertial system TargetR j _t, speed TargetV j _t, and calculate the vector Sun2Target pointing to the space debris from the sun j ;

[0044] The orbit extrapolation method under the J2 perturbation model is used to extrapolate the probe's orbit, and the position SatR_t and velocity SatV_t of the probe in the J2000 inertial system are calculated;

[0045] Calculate the space debris targets that meet the filter conditions SelectTargetData j The relative angle on the detector is further calculated from the three-axis vector of the detector; the target whose relative angle is smaller than the angle constraint of the detector is output, thereby realizing the simulation of the detector's space target recognition data.

[0046] The relative angle on the detector

[0047]

[0048] in,

[0049] Coi: Transformation matrix from the spacecraft orbital system to the inertial system where the probe is located;

[0050] Cbo: Conversion matrix between the spacecraft system and the orbital system where the probe is located;

[0051] Czb: spacecraft visible light detector to the system installation matrix;

[0052] Cez: Transformation matrix from detector output coordinate system to detector installation coordinate system;

[0053] Re xj _t、Re yj _t、Re zj _t: vector x, y, z axis components of the target vector on the detector;

[0054] The relative angle between the X and Y axes of the target on the detector.

[0055] The space debris target that meets the screening conditions SelectTargetData j The three-axis vector of the detector Re = Cez*Czb*Cbo*Coi*Sat2TargetR j _t.

[0056] The advantages of the present invention compared with the prior art are:

[0057] Taking into account the detection constraints and performance characteristics of visible light detectors, and combining the target equivalent simulation situation, a hierarchical combination simulation method of computer large-step target screening + real-time system small-step target orbit calculation + real-time system visible light detector period simulation was designed. The complex calculation function of ground simulation was realized through the hierarchical combination of low-cost modules, and the experimental verification of the space debris target detection function based on visible light detectors in the ground semi-physical simulation environment was effectively realized.

[0058] Taking into account the detection constraints and performance characteristics of visible light detectors, and combining the target equivalent simulation situation, a hierarchical combination simulation method of computer large-step target screening + real-time system small-step target orbit calculation + real-time system visible light detector period simulation was designed. The complex calculation function of ground simulation was realized through the hierarchical combination of low-cost modules, and the experimental verification of the space debris target detection function based on visible light detectors in the ground semi-physical simulation environment was effectively realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Schematic diagram of the relationship between the positions of space debris, the sun and the probe. DETAILED DESCRIPTION

[0060] The present invention provides a ground simulation method for space debris visible light detector identification data, and the hardware involved is composed of an orbit screening computer and a test host with a real-time system. The orbit screening computer implements large-step periodic space target screening, screens out targets that can be identified by visible light detectors, and sends them to the test host; the test host with a real-time system implements small-step orbit extrapolation of the target, and at the same time implements simulation of visible light detector identification data based on real-time satellite attitude, orbit, target lighting environment, reflectivity, relative distance and other information. The specific steps are as follows:

[0061] Step 1: Establish a detectable energy model for space debris targets. Space debris can generate energy by reflecting sunlight in space. Optical sensors detect debris by sensing the reflected energy. The schematic diagram of the relationship between space debris, the sun, and the sensor is shown in the figure below. Figure 1 As shown. The detection energy can be equivalent to the magnitude, which is related to the detection distance, debris albedo and phase angle. The target detectable energy equivalent model is as follows:

[0062]

[0063] in:

[0064] m VThe target's equivalent apparent magnitude. The smaller the value, the higher the brightness. It can clearly give the brightness level of the target's reflected light compared to the star background. It is often used to characterize the target's detectable energy.

[0065] m SUN is the solar equivalent apparent magnitude;

[0066] A is the equivalent reflection area;

[0067] ρ is the target reflectivity, which is mainly related to the target surface material;

[0068] for Figure 1 The phase angle in is the attenuation function of the brightness of the target reflected light as the observation direction and the sunlight irradiation direction are different;

[0069] r is the distance between the target and the detector;

[0070] C1, C2 are constant coefficients.

[0071] Step 2: Receive the current satellite time SatT, the current orbital position SatR, and the velocity SatV of the probe spacecraft sent by the test host in real time, select the space debris target set SelectTargetData that meets the detectable constraints from the space debris target library, and send it to the test host;

[0072] a. The bound space debris target library is

[0073]

[0074] Where i = 1, 2, ..., N1, N1 is the number of space debris target libraries; TLE is the number of two-row orbital elements of space debris target i;

[0075] b. Orbit selection is performed according to the period T, where T = the shortest mission execution time of the entire satellite / 2;

[0076] c. Use the SGP4 / SDP4 model to perform orbital extrapolation on all space debris targets (orbital extrapolation time t = SatT, SatT+T, SatT+2T) and calculate the ALLTargetData of each space debris target i Position TargetR in J2000 inertial system i _t, speed TargetV i _t, and calculate the vector Sun2Target pointing to the space debris from the sun i ;

[0077] d. Use the orbit extrapolation method under the J2 perturbation model to extrapolate the probe's orbit (orbit extrapolation time t = SatT, SatT + T, SatT + 2T), and calculate the position SatR_t and velocity SatV_t of the probe in the J2000 inertial system;

[0078] e. Calculate the target vector Sat2TargetR of the detector pointing to the space debris i _t=TargetR i _t-SatR_t, further derive the space debris target ALLTargetData i The detection distance r from the detector at time t i _t=|Sat2TargetR i _t|;

[0079] f. Calculate the space debris target ALLTargetData i The phase angle with the detector at time t

[0080]

[0081] g. Substitute the results of e and f into the model in step 1 to calculate the space debris target ALLTargetData i The detectable energy m at the detector position at time i vi _t;

[0082] h. Calculate the space debris target ALLTargetData i The relative velocity of the detector at time i is Sat2TargetV i _t=TargetV i _t-SatV_t, and calculate the relative angular velocity

[0083]

[0084] i. For all time t, all space debris targets ALLTargetData i The following conditions are screened: 1) m vi _t≤m max 2)ω i _t≤ω max

[0085] The space debris target set SelectTargetData that meets the screening conditions is sent to the test host.

[0086] Step 3: The test host continues to periodically simulate the received space debris target set SelectTargetData, and calculates the detector's recognition data of space debris targets in real time:

[0087] a. Use SGP4 / SDP4 model to select target data of space debris j Extrapolate the orbits of all targets in the (j=1,2,…,N2, N2 is the number of space targets after screening) and calculate the position TargetR of each target in the J2000 inertial system j _t, speed TargetV j _t, and calculate the vector Sun2Target pointing to the space debris from the sun j ;

[0088] b. Use the orbit extrapolation method under the J2 perturbation model to extrapolate the probe's orbit and calculate the position SatR_t and velocity SatV_t of the probe in the J2000 inertial system;

[0089] c. According to steps 2e to 2i, calculate the space debris target SelectTargetData that meets the screening conditions in real time j ;

[0090] d. SelectTargetData based on the space debris targets that meet the screening requirements j , calculate its three-axis vector Re = Cez*Czb*Cbo*Coi*Sat2TargetR on the detector j _t, further calculate the relative angle on the detector

[0091]

[0092] in,

[0093] Coi: Transformation matrix from the spacecraft orbital system to the inertial system where the probe is located;

[0094] Cbo: Conversion matrix between the spacecraft system and the orbital system where the probe is located;

[0095] Czb: spacecraft visible light detector to the system installation matrix;

[0096] Cez: Transformation matrix from detector output coordinate system to detector installation coordinate system;

[0097] Re xj _t、Re yj _t、Re zj _t: vector x, y, z axis components of the target vector on the detector;

[0098] Relative angle identification data of the target on the detector on the X and Y axes;

[0099] e. Output targets whose relative angles are smaller than the detector angle constraint, thus realizing the simulation of the detector's recognition data of space targets.

[0100] 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 can make possible changes and modifications to the technical solution of the present invention by using the 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 ground simulation method for space debris visible light detector identification data, characterized in that: include: Establishing a target detectable energy model for space debris; Receive the current satellite time SatT, current orbital position SatR and velocity SatV of the probe spacecraft sent by the test host in real time, select the space debris target set SelectTargetData that meets the detectable constraints from the space debris target library and send it to the test host; The test host performs periodic simulation on the received space debris target set SelectTargetData, calculates the detector's recognition data of space debris targets in real time, and completes the simulation of the detector's recognition data of space targets.

2. A ground simulation method for space debris visible light detector identification data according to claim 1, characterized in that: The method of establishing a target detectable energy model of space debris comprises: Space debris generates energy by reflecting sunlight in space. Optical sensors detect space debris by sensing the reflected energy of debris. The detected energy is equivalent to the magnitude of the star, which is related to the detection distance, debris albedo and phase angle. The target detectable energy model is as follows: in: m V is the target equivalent apparent magnitude, the smaller the value, the higher the brightness; m SUN is the solar equivalent apparent magnitude; A is the equivalent reflection area; ρ is the target reflectivity; is the phase angle; is the attenuation function of the brightness of the target reflected light as the observation direction and the sunlight irradiation direction are different; r is the distance between the target and the detector; C1, C2 are constant coefficients.

3. The method for simulating space debris visible light detector identification data on the ground according to claim 1, characterized in that: The step of selecting a space debris target set SelectTargetData that meets the detectable constraint from the space debris target library includes: Assume that the bound space debris target library is Where i = 1, 2, ..., N1, N1 is the number of space debris target libraries; TLE is the number of two-row orbital elements of space debris target i; Orbit screening is performed according to period T, and the orbits of all space debris targets are extrapolated using the SGP4 / SDP4 model. The orbit extrapolation time t = SatT, SatT+T, SatT+2T is calculated to obtain ALLTargetData of each space debris target. i Position TargetR in J2000 inertial system i _t, speed TargetV i _t, and calculate the target ALLTargetData of each space debris i Vector Sun2Target with space debris pointing to the sun i ; The orbit extrapolation method under the J2 perturbation model is used to extrapolate the orbit of the probe. The orbit extrapolation time t = SatT, SatT+T, SatT+2T, and the position SatR_t and velocity SatV_t of the probe in the J2000 inertial system are calculated; The target vector Sat2TargetR of the detector pointing to the space debris is calculated i _t=TargetR i _t-SatR_t, further derive the space debris target ALLTargetData i The detection distance r from the detector at time t i _t=|Sat2TargetR i _t|; Calculate the space debris target ALLTargetData i The phase angle with the detector at time t The detection distance r i _t and phase angle Substitute the target detectable energy model of space debris to obtain the space debris target ALLTargetData i The detectable energy m at the detector position at time i vi _t; Calculate the space debris target ALLTargetData i The relative velocity of the detector at time i is Sat2TargetV i _t=TargetV i _t-SatV_t, and calculate the relative angular velocity ω i _t; For all time t, all space debris targets ALLTargetData i Perform conditional screening; send the space debris target set SelectTargetData that meets the screening conditions to the test host.

4. The method for simulating space debris visible light detector identification data on the ground according to claim 3, characterized in that: The period T=the shortest task execution time of the entire satellite / 2.

5. The method for simulating space debris visible light detector identification data on the ground according to claim 3, characterized in that: The space debris target ALLTargetData i The phase angle with the detector at time t 6. The method for simulating space debris visible light detector identification data on the ground according to claim 5, characterized in that: The relative angular velocity 7. A ground simulation method for space debris visible light detector identification data according to claim 6, characterized in that: For all time t, all space debris targets ALLTargetData i Perform conditional screening, the screening conditions are: 1)m vi _t≤m max 2)oh i _t≤ω max Among them, m max Indicates the maximum sensitivity of the visible light detector, ω max Indicates that the visible light detector recognizes the maximum relative angular velocity; satisfying the above two conditions at the same time means that the screening conditions are met.

8. The method for simulating space debris visible light detector identification data on the ground according to claim 7, characterized in that: The test host periodically simulates the received space debris target set SelectTargetData, and calculates the space debris target identification data of the detector in real time, including: Use SGP4 / SDP4 model to select target data of space debris j Extrapolate the orbits of all targets in j = 1, 2, ..., N2, where N2 is the number of space targets after screening; calculate the position of each target in the J2000 inertial system TargetR j _t, speed TargetV j _t, and calculate the vector Sun2Target pointing to the space debris from the sun j ; The orbit extrapolation method under the J2 perturbation model is used to extrapolate the probe's orbit, and the position SatR_t and velocity SatV_t of the probe in the J2000 inertial system are calculated; Calculate the space debris targets that meet the filter conditions SelectTargetData j The relative angle on the detector is further calculated from the three-axis vector of the detector; the target whose relative angle is smaller than the angle constraint of the detector is output, thereby realizing the simulation of the detector's space target recognition data.

9. The method for simulating space debris visible light detector identification data on the ground according to claim 8, characterized in that: The relative angle on the detector in, Coi: Transformation matrix from the spacecraft orbital system to the inertial system where the probe is located; Cbo: Conversion matrix between the spacecraft system and the orbital system where the probe is located; Czb: spacecraft visible light detector to the system installation matrix; Cez: Transformation matrix from detector output coordinate system to detector installation coordinate system; Re xj _t、Re yj _t、Re zj _t: vector x, y, z axis components of the target vector on the detector; The relative angle between the X and Y axes of the target on the detector.

10. A ground simulation method for space debris visible light detector identification data according to claim 9, characterized in that: The space debris target that meets the screening conditions SelectTargetData j The three-axis vector of the detector Re = Cez*Czb*Cbo*Coi*Sat2TargetR j _t.

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