Ground target-oriented spaceborne laser full-autonomous calibration method
By autonomously calculating and calibrating the emission time and attitude data of the satellite, autonomous calibration of the spaceborne laser payload has been achieved, solving the problems of cumbersome procedures and dependence on ground systems in the existing technology, and improving calibration accuracy and efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA ACADEMY OF SPACE TECHNOLOGY
- Filing Date
- 2026-03-10
- Publication Date
- 2026-06-02
AI Technical Summary
Existing methods for calibrating spaceborne laser payloads have lengthy and cumbersome processes, rely on ground system coordination, consume a lot of human resources, and are easily constrained by rapid and high-precision ground-based orbit data forecasts, thus failing to meet the operational and high-frequency calibration requirements.
The fully autonomous calibration method for spaceborne lasers is adopted. The satellite autonomously calculates and calibrates the emission time and attitude data, eliminating the complex manual calibration process on the ground. The satellite autonomously calculates orbit extrapolation and attitude optimization to achieve autonomous calibration of the laser payload.
It simplifies the calibration process, reduces costs, improves calibration accuracy and efficiency, and enhances the success rate and accuracy of calibration tasks.
Smart Images
Figure CN122131280A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a fully autonomous calibration method for spaceborne lasers targeting ground targets, belonging to the field of aerospace remote sensing technology. Background Technology
[0002] After a satellite is launched into orbit, its onboard laser payloads (such as laser altimeters and lidar) will experience pointing errors due to structural deformation caused by stress release during launch. During the satellite's operation in orbit, internal parameters (such as laser pointing angle, spot energy, and time synchronization) will also drift due to changes in the space environment and component aging, leading to a decrease in geometric or radiometric measurement accuracy. Therefore, from launch to the end of its lifespan, the laser payload must undergo multiple on-orbit calibrations to ensure the laser's pointing accuracy.
[0003] Current calibration methods require ground personnel to plan calibration tests in advance. Satellite users calculate the satellite's attitude maneuver angles based on orbit determination results and transmit these angles to the satellite developer. The developer, in conjunction with the satellite tracking and control unit, then sends attitude maneuver commands. When the satellite flies over a specific calibration field, ground personnel manually activate the calibration mode. Ground data receivers receive the downlink data and perform complex data processing on the ground. Therefore, existing calibration methods have the following problems: 1) The process chain is lengthy and the procedures are cumbersome, and it is constrained by the rapid and high-precision orbital data forecasting based on the ground. 2) The timing of the uploading command is tight, relying on the coordinated operation of multiple systems such as the ground receiving system, ground application system, ground telemetry and control system, and satellite development system.
[0004] 3) The calibration plan needs to be strictly formulated in advance. From the discovery of accuracy problems, mission planning, precise attitude and orbit calculation, instruction input to ground target coordination, the cycle is long and consumes a lot of human resources. Any error in any link will lead to mission failure. The engineering cost is high and it cannot meet the operational and high-frequency calibration needs.
[0005] In summary, existing calibration methods are lengthy, cumbersome, and require significant human resources; furthermore, a problem in any step of the calibration process can severely impact calibration accuracy. Therefore, there is an urgent need for a highly autonomous and streamlined spaceborne laser calibration method. Summary of the Invention
[0006] The technical problem solved by this invention is to overcome the shortcomings of existing technologies and provide a fully autonomous calibration method for spaceborne lasers targeting ground-based targets. This method autonomously calculates the emission time and attitude data of the satellite to complete the calibration of the laser payload, eliminating the need for complex manual calibration procedures on the ground and solving the problems of existing methods requiring ground personnel, cumbersome procedures, and unstable calibration accuracy.
[0007] The technical solution of this invention is: A fully autonomous calibration method for spaceborne lasers targeting ground-based targets, comprising the following steps: (1) The ground system obtains a rough estimate of the calibration emission time based on the satellite orbit and target latitude and longitude position information, combined with the allowable attitude maneuver range of the satellite laser payload; (2) Based on the rough estimate of the calibration output time, calculate the start command transmission time; the ground system sends the laser calibration start command to the satellite at the start command transmission time; (3) After receiving the laser calibration start command, the satellite performs the first orbit extrapolation calculation to obtain the first orbit extrapolation result; based on the first orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target and the laser payload observation target constraint conditions, the calibration light output time is obtained; (4) Calculate the second-order optimization time based on the calibration light output time; (5) The satellite performs a second orbit extrapolation calculation at the second optimization time to obtain the second orbit extrapolation result; based on the second orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target and the constraints of the laser payload observation target, the optimal calibration light emission time and the optimal three-axis attitude pointing angle are obtained; (6) Based on the optimal three-axis attitude pointing angle, control the optical axis of the laser payload on the satellite to point towards the center of the target; (7) Control the laser payload on the satellite to emit laser at the optimal calibration emission time; based on the position of the laser on the target, correct the laser payload parameters and complete the calibration of the laser payload; (8) Control the satellite attitude back to the normal zero attitude relative to the ground and end the calibration mission.
[0008] Furthermore, based on the rough estimate of the calibration light emission time, the formula for calculating the start command transmission time T1 is as follows: T1 = T0 - T s Where T0 is a rough estimate of the calibration light emission time; T s For greater than T wt Any duration; T wt This is the satellite extrapolation time.
[0009] Furthermore, the specific steps to obtain the calibration light emission time are as follows: The first step is to calculate the satellite's orbital prediction data relative to the ground calibration field based on the extrapolation results of the first orbit; The second step is to find all the moments during the satellite's on-orbit operation that meet the laser payload observation target constraints, based on the orbital prediction data, the current laser installation matrix, and the latitude and longitude of the ground target, and to compile these moments into a time set. The third step is to evaluate the maneuverability of the satellite at each time point in the time set and select the time point with the best maneuverability as the calibration time point.
[0010] Furthermore, the formula for calculating the second optimization time T2 is as follows: T2 = T' - T D Where T' is the calibration light emission time, T D For satellite precision forecasting and maneuver stabilization duration.
[0011] Furthermore, based on the extrapolation results of the second orbit, the optimal calibration emission time is obtained as follows: The first step is to calculate the optimal orbit prediction data of the satellite relative to the ground calibration field based on the extrapolation results of the second orbit. The second step is to find all the moments during the satellite's on-orbit operation that meet the laser payload observation target constraints, based on the optimal orbit prediction data, the current laser installation matrix, and the latitude and longitude of the ground target, and to compile these moments into a time set. The third step is to evaluate the maneuverability of the satellite at each time point in the time set and select the time point with the best maneuverability as the optimal calibration time.
[0012] Furthermore, based on the extrapolation results of the second orbit, the specific three-axis attitude pointing angles are obtained as follows: The first step is to calculate the satellite position at the optimal calibration light emission time based on the extrapolation results of the second orbit; The second step is to calculate the vector from the satellite to the center of the ground calibration field based on the satellite's position and the latitude and longitude of the ground target at the optimal calibration light output time. The third step is to calculate the three-axis attitude pointing angle based on the vector from the satellite to the center of the ground calibration field and the current laser installation matrix.
[0013] Secondly, this invention also proposes a fully autonomous satellite-borne laser calibration system for ground targets. The fully autonomous satellite-borne laser calibration system is deployed on a satellite and includes a data management subsystem and a control subsystem. The ground system obtains a rough estimate of the calibration emission time based on the satellite orbit and target latitude and longitude position information, combined with the allowable attitude maneuver range of the satellite laser payload; based on the rough estimate of the calibration emission time, it calculates the start command transmission time; at the start command transmission time, the ground system sends the laser calibration start command to the data management subsystem on the satellite; After receiving the laser calibration start command, the data management subsystem forwards it to the control subsystem. Upon receiving the command, the control subsystem performs the first orbit extrapolation calculation to obtain the first orbit extrapolation result. Based on the first orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the control subsystem obtains the calibration emission time and calculates the secondary optimization time. At the secondary optimization time, the control subsystem performs the second orbit extrapolation calculation to obtain the second orbit extrapolation result. Based on the second orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the control subsystem obtains the optimal calibration emission time and the optimal three-axis attitude pointing angle. Based on the optimal three-axis attitude pointing angle, the control subsystem controls the optical axis of the laser payload on the satellite to point towards the center of the target; at the same time, the data management subsystem controls the laser payload on the satellite to emit laser at the optimal calibration emission time; based on the position of the laser on the target, the ground system corrects the laser payload parameters and completes the calibration of the laser payload; finally, the control subsystem controls the satellite attitude to return to the normal zero attitude of the ground, and ends the calibration mission.
[0014] Furthermore, based on the rough estimate of the calibration light emission time, the formula for calculating the start command transmission time T1 is as follows: T1 = T0 - T s Where T0 is a rough estimate of the calibration light emission time; T s For greater than T wt Any duration; T wt This refers to the satellite extrapolation time. The formula for calculating the second-order optimization time T2 in the control subsystem is: T2 = T' - T D Where T' is the calibration light emission time, T D For satellite precision forecasting and maneuver stabilization duration.
[0015] Furthermore, the specific steps for the control subsystem to obtain the calibrated light output time are as follows: The first step is to calculate the satellite's orbit prediction data relative to the ground calibration field based on the extrapolation results of the first orbit. The second step is to use the orbital prediction data, the current laser installation matrix, and the latitude and longitude of the ground target to find all the moments during the satellite's on-orbit operation that meet the laser payload observation target constraints and to compile these moments into a time set. The third step is for the control subsystem to evaluate the maneuverability of the satellite at each time point in the time set and select the time point with the best maneuverability as the calibration time point.
[0016] Furthermore, based on the extrapolation results of the second orbit, the control subsystem obtains the optimal calibration light emission time as follows: The first step is to calculate the optimal orbit prediction data of the satellite relative to the ground calibration field based on the second orbit extrapolation results; The second step is to use the optimal orbit prediction data, the current laser installation matrix and the latitude and longitude of the ground target to find all the moments during the satellite's on-orbit operation that meet the laser payload observation target constraints and to compile these moments into a time set. The third step is for the control subsystem to evaluate the maneuverability of the satellite at each time in the time set and select the time with the best maneuverability as the optimal calibration time. Based on the extrapolation results of the second orbit, the control subsystem obtains the following specific three-axis attitude pointing angles: The first step is to calculate the satellite position at the optimal calibration light emission time based on the extrapolation results of the second orbit. The second step is to calculate the vector from the satellite to the center of the ground calibration field based on the satellite's position and the latitude and longitude of the ground target at the optimal calibration light output time. The third step involves the control subsystem calculating the three-axis attitude pointing angles based on the vector from the satellite to the center of the ground calibration field and the current laser installation matrix.
[0017] The advantages of this invention compared to the prior art are: (1) This invention completes the calibration of the laser payload by autonomously calculating and calibrating the light output time and attitude data of the satellite, eliminating the complex manual calibration process on the ground, simplifying the entire calibration process, reducing the cost required in the calibration process, and improving the calibration accuracy and efficiency.
[0018] (2) When the time of light emission is closer to the calibration time, the present invention uses the precise orbit determination data of the navigation satellite system to calculate the optimal light emission time and attitude angle for the second time, which further improves the calibration accuracy and the success rate of the calibration task. Attached Figure Description
[0019] Figure 1 This is a flowchart of a fully autonomous calibration method for spaceborne lasers targeting ground targets according to the present invention. Figure 2 This is a time planning segment diagram for a fully autonomous calibration method for spaceborne lasers targeting ground-based targets according to the present invention. Figure 3 This is a diagram illustrating the laser-driven autonomous calibration attitude maneuver process in a simulation of an example of this invention. Detailed Implementation
[0020] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.
[0021] like Figure 1 As shown, this invention provides a fully autonomous calibration method for spaceborne lasers targeting ground-based targets, with the following steps: (1) The ground system obtains a rough estimate of the calibration emission time based on the satellite orbit and target latitude and longitude position information, combined with the allowable attitude maneuver range of the satellite laser payload; The specific steps for obtaining the rough estimate of the calibration emission time are as follows: the ground system calculates the satellite orbit prediction result based on the satellite orbit historical data and high-precision orbit dynamics model; based on the satellite orbit prediction result, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the rough estimate of the calibration emission time is calculated.
[0022] (2) Based on the rough estimate of the calibration output time, calculate the start command transmission time; the ground system sends the laser calibration start command to the satellite at the start command transmission time; Based on the rough estimate of the calibration light emission time, the formula for calculating the start command transmission time T1 is as follows: T1 = T0 - T s Where T0 is a rough estimate of the calibration light emission time; T s For greater than T wt Any duration; T wt This is the satellite extrapolation time.
[0023] (3) After receiving the laser calibration start command, the satellite performs the first orbit extrapolation calculation to obtain the first orbit extrapolation result; based on the first orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the calibration emission time is obtained. The specific steps are as follows: (3.1) Based on the first orbit extrapolation result, calculate the satellite orbit prediction data relative to the ground calibration field; the satellite orbit extrapolation algorithm is the Chebyshev polynomial fitting algorithm; (3.2) Based on the orbit prediction data, the current laser installation matrix and the latitude and longitude of the ground target, find all the times during the satellite's on-orbit operation that meet the laser payload observation target constraints, and form these times into a time set; The constraints on the laser payload observation target include at least one of the following: satellite attitude pointing accuracy constraints, spatial constraints of laser beam coverage of the ground calibration field, and communication link constraints between the satellite and the ground calibration field.
[0024] (3.3) Evaluate the maneuverability of the satellite at each time point in the time set, and select the time point with the best maneuverability as the calibration time point; The maneuverability indicators include momentum wheel energy consumption and attitude adjustment range indicators; the lower the fuel consumption, the better the momentum wheel energy consumption indicator; the smaller the attitude adjustment range, the better the attitude adjustment range indicator. The process of evaluating satellite maneuverability and selecting the optimal moment for calibration and light emission involves the following steps: First, calculate the momentum wheel energy consumption and attitude adjustment range of the satellite at each moment. Then, calculate the weighted sum of the momentum wheel energy consumption and attitude adjustment range, with the weights determined based on the actual mission performed by the satellite. If the mission places a higher constraint on fuel consumption than on attitude adjustment range, the momentum wheel energy consumption index will have a larger weight; otherwise, the attitude adjustment range index will have a larger weight. Finally, calculate the weighted sum of the momentum wheel energy consumption and attitude adjustment range at each moment, and select the moment with the smallest weighted sum as the light emission moment.
[0025] (4) Based on the calibration light emission time, calculate the secondary optimization time. The calculation formula is as follows: T2 = T' - T D Where T' is the calibration light emission time, T D For satellite precision forecasting and maneuver stabilization duration.
[0026] (5) The satellite performs a second orbit extrapolation calculation at the second optimization time to obtain the second orbit extrapolation result; based on the second orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target and the constraints of the laser payload observation target, the optimal calibration light emission time and the optimal three-axis attitude pointing angle are obtained; The optimal calibration light emission time is obtained as follows: (5.1) Based on the second orbit extrapolation results, calculate the optimal orbit prediction data of the satellite relative to the ground calibration field; (5.2) Based on the optimal orbit prediction data, the current laser installation matrix and the latitude and longitude of the ground target, find all the times during the satellite's on-orbit operation that meet the laser payload observation target constraints, and form a time set of these times; (5.3) Evaluate the maneuver index of the satellite at each time in the time set, and select the time with the best maneuver index as the optimal calibration time.
[0027] The three-axis attitude pointing angles are obtained as follows: (5.4) Based on the extrapolation results of the second orbit, calculate the satellite position at the optimal calibration light emission time; (5.5) Based on the satellite position and the latitude and longitude of the ground target at the optimal calibration light output time, calculate the vector from the satellite to the center of the ground calibration field; (5.6) Based on the vector from the satellite to the center of the ground calibration field and the current laser installation matrix, calculate the three-axis attitude pointing angle.
[0028] (6) Based on the optimal three-axis attitude pointing angle, control the optical axis of the laser payload on the satellite to point towards the center of the target.
[0029] (7) Control the laser payload on the satellite to emit laser at the optimal calibration emission time; based on the position of the laser on the target, correct the laser payload parameters and complete the calibration of the laser payload.
[0030] (8) Control the satellite attitude back to the normal zero attitude of the ground and end the calibration mission; the normal zero attitude of the ground refers to the spacecraft body coordinate system being completely coincident with the local geographic coordinate system, with roll angle, pitch angle and yaw angle all being 0°, the spacecraft reference plane pointing vertically to the center of the earth, stably facing the earth and without any deflection.
[0031] Secondly, this invention also proposes a fully autonomous satellite-borne laser calibration system for ground targets. The fully autonomous satellite-borne laser calibration system is deployed on a satellite and includes a data management subsystem and a control subsystem. The ground system obtains a rough estimate of the calibration emission time based on the satellite orbit and target latitude and longitude position information, combined with the allowable attitude maneuver range of the satellite laser payload; based on the rough estimate of the calibration emission time, it calculates the start command transmission time; at the start command transmission time, the ground system sends the laser calibration start command to the data management subsystem on the satellite; After receiving the laser calibration start command, the data management subsystem forwards it to the control subsystem. Upon receiving the command, the control subsystem performs the first orbit extrapolation calculation to obtain the first orbit extrapolation result. Based on the first orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the control subsystem obtains the calibration emission time and calculates the secondary optimization time. At the secondary optimization time, the control subsystem performs the second orbit extrapolation calculation to obtain the second orbit extrapolation result. Based on the second orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the control subsystem obtains the optimal calibration emission time and the optimal three-axis attitude pointing angle. Based on the optimal three-axis attitude pointing angle, the control subsystem controls the optical axis of the laser payload on the satellite to point towards the center of the target; at the same time, the data management subsystem controls the laser payload on the satellite to emit laser at the optimal calibration emission time; based on the position of the laser on the target, the ground system corrects the laser payload parameters and completes the calibration of the laser payload; finally, the control subsystem controls the satellite attitude to return to the normal zero attitude of the ground, and ends the calibration mission.
[0032] Example: The laser payload on the satellite was calibrated using targets in the calibration field. The parameters of the targets in the calibration field are shown in Table 1, and the orbital data of the satellite are shown in Table 2.
[0033] Table 1 Target Parameters
[0034] Table 2 Satellite orbital data
[0035] The operations performed by the entire method at different time periods are as follows: Figure 2 As shown, the process is as follows: (1) The ground system obtains a rough estimate of the calibration emission time based on the satellite orbit and target latitude and longitude position information, combined with the allowable attitude maneuver range of the satellite laser payload; the rough estimate of the calibration emission time is T0=620s; (2) Based on the rough estimate of the calibration output time, calculate the start command transmission time; the ground system sends the laser calibration start command to the satellite at the start command transmission time; The formula for calculating the time T1 when the start command is sent is: T1 = T0 - T s Among them, T s =30h.
[0036] (3) After receiving the laser calibration start command, the satellite performs the first orbit extrapolation calculation to obtain the first orbit extrapolation result; based on the first orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the calibration emission time is obtained. The specific process is as follows: (3.1) Based on the extrapolation results of the first orbit, calculate the orbit prediction data of the satellite relative to the ground calibration field; (3.2) Based on the orbit prediction data, the current laser installation matrix and the latitude and longitude of the ground target, find all the times during the satellite's on-orbit operation that meet the laser payload observation target constraints, and form these times into a time set; (3.3) Evaluate the maneuverability of the satellite at each time point in the time set, and select the time point with the best maneuverability as the calibration time point; The entire above can be viewed as an optimization problem, and the specific expression of the optimization problem is: min
[0037] st
[0038]
[0039]
[0040] (4) Based on the calibration light emission time, calculate the secondary optimization time using the following formula: T2 = T' - T D Where T' is the calibration light emission time, T D For satellite precision forecasting and maneuver stabilization duration, T D =240s.
[0041] (5) The satellite performs a second orbit extrapolation calculation at the second optimization time to obtain the second orbit extrapolation result; based on the second orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target and the laser payload observation target constraints, the optimal calibration light emission time and the optimal three-axis attitude pointing angle are obtained; the three-axis attitude pointing angle is [-0.042°, -0.015°, 0.000°].
[0042] (6) Based on the optimal three-axis attitude pointing angle, control the optical axis of the laser payload on the satellite to point towards the center of the target; (7) Control the laser payload on the satellite to emit laser at the optimal calibration emission time; based on the position of the laser on the target, correct the laser payload parameters and complete the calibration of the laser payload; (8) Control the satellite attitude back to the normal zero attitude relative to the ground and end the calibration mission.
[0043] In summary, the actual control process is as follows: Figure 3 As shown, specifically: first, perform attitude maneuver to prepare to change the attitude direction, that is, execute steps (1) to (5); then, perform state adjustment and maintain the adjusted attitude, that is, execute steps (6) to (7); finally, return to the zero attitude, that is, execute step (8).
[0044] In this embodiment, the laser calibration command is injected at 6400s. After 7655 seconds of simulation, the coarse prediction is completed, and the emission time T0 = 620s. The coarse prediction yields a roll angle of -0.081 degrees and an elevation angle of 0.804 degrees. The fine prediction is completed at 90387.75 seconds, finding the roll and elevation angles corresponding to the minimum elevation angle of the satellite relative to the calibration field. The fine prediction yields a roll angle of -0.042 degrees and an elevation angle of -0.015 degrees.
[0045] Without considering control execution errors, using a roll angle of -0.042 degrees and a pitch angle of -0.015 degrees (corresponding to line-of-sight attitudes: roll -0.757°, pitch -0.055°), the calculated pointing error between the geographical latitude and longitude of the laser pointing to the ground and the actual latitude and longitude is [-0.039740203527978, 0.007792196832228] (meters). Assuming a calibration field with a ground area of hundreds of meters, the satellite's autonomous calibration pointing error is much smaller than the calibration field size, enabling precise pointing.
[0046] The parts of this invention not described in detail are common knowledge to those skilled in the art.
Claims
1. A fully autonomous calibration method for spaceborne lasers targeting ground-based targets, characterized in that, include: Based on the satellite orbit and target latitude and longitude location information, combined with the permissible attitude maneuver range of the satellite laser payload, the ground system obtains a rough estimate of the calibration emission time. Based on the rough estimate of the calibration light emission time, the start command transmission time is calculated; the ground system sends the laser calibration start command to the satellite at the start command transmission time. After receiving the laser calibration start command, the satellite performs the first orbit extrapolation calculation and obtains the first orbit extrapolation result; Based on the extrapolation results of the first orbit, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the calibration emission time is obtained. Based on the calibrated light emission time, the secondary optimization time is calculated; The satellite performs a second orbit extrapolation calculation at the second optimization time, and obtains the second orbit extrapolation result; Based on the extrapolation results of the second orbit, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the optimal calibration emission time and the optimal three-axis attitude pointing angle are obtained. Based on the optimal three-axis attitude pointing angle, the optical axis of the laser payload on the satellite is controlled to point towards the center of the target; The laser payload on the control satellite emits laser light at the optimal calibration emission time; based on the position of the laser on the target, the laser payload parameters are corrected to complete the calibration of the laser payload; The satellite attitude was brought back to its normal zero attitude relative to the Earth, thus ending the calibration mission.
2. The fully autonomous calibration method for spaceborne lasers targeting ground-based targets according to claim 1, characterized in that: Based on the rough estimate of the calibration light emission time, the formula for calculating the start command transmission time T1 is as follows: T1=T0-T s Where T0 is a rough estimate of the calibration light emission time; T s For greater than T wt Any duration; T wt This is the satellite extrapolation time.
3. The fully autonomous calibration method for spaceborne lasers targeting ground-based targets according to claim 1, characterized in that: The specific steps to obtain the calibration light emission time are as follows: The first step is to calculate the satellite's orbital prediction data relative to the ground calibration field based on the extrapolation results of the first orbit. The second step is to find all the moments during the satellite's on-orbit operation that meet the laser payload observation target constraints, based on the orbital prediction data, the current laser installation matrix, and the latitude and longitude of the ground target, and to compile these moments into a time set. The third step is to evaluate the maneuverability of the satellite at each time point in the time set and select the time point with the best maneuverability as the calibration time point.
4. The fully autonomous calibration method for spaceborne lasers targeting ground-based targets according to claim 1, characterized in that: The formula for calculating the second optimization time T2 is: T2=T’-T D Where T' is the calibration light emission time, T D For satellite precision forecasting and maneuver stabilization duration.
5. The fully autonomous calibration method for spaceborne lasers targeting ground-based targets according to claim 1, characterized in that: The optimal calibration light emission time is obtained as follows: The first step is to calculate the optimal orbit prediction data of the satellite relative to the ground calibration field based on the extrapolation results of the second orbit. The second step is to find all the moments during the satellite's on-orbit operation that meet the laser payload observation target constraints, based on the optimal orbit prediction data, the current laser installation matrix, and the latitude and longitude of the ground target, and to compile these moments into a time set. The third step is to evaluate the maneuverability of the satellite at each time point in the time set and select the time point with the best maneuverability as the optimal calibration time.
6. The fully autonomous calibration method for spaceborne lasers targeting ground-based targets according to claim 1, characterized in that: The three-axis attitude pointing angles are obtained as follows: The first step is to calculate the satellite position at the optimal calibration light emission time based on the extrapolation results of the second orbit; The second step is to calculate the vector from the satellite to the center of the ground calibration field based on the satellite's position and the latitude and longitude of the ground target at the optimal calibration light output time. The third step is to calculate the three-axis attitude pointing angle based on the vector from the satellite to the center of the ground calibration field and the current laser installation matrix.
7. A fully autonomous spaceborne laser calibration system for ground-based targets, characterized in that: The spaceborne laser fully autonomous calibration system is deployed on the satellite and includes a data management subsystem and a control subsystem. Based on the satellite orbit and target latitude and longitude location information, combined with the permissible attitude maneuver range of the satellite laser payload, the ground system obtains a rough estimate of the calibration emission time. Based on the rough estimate of the calibration light emission time, the start command transmission time is calculated; at the start command transmission time, the ground system sends the laser calibration start command to the data management subsystem on the satellite; After receiving the laser calibration start command, the data management subsystem forwards the command to the control subsystem. Upon receiving the command, the control subsystem performs the first orbit extrapolation calculation to obtain the first orbit extrapolation result. Based on the first orbit extrapolation result, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the control subsystem obtains the calibration emission time and calculates the secondary optimization time. At the secondary optimization time, the control subsystem performs the second orbit extrapolation calculation to obtain the second orbit extrapolation result. Based on the extrapolation results of the second orbit, the current laser installation matrix, the latitude and longitude of the ground target, and the constraints of the laser payload observation target, the control subsystem obtains the optimal calibration light emission time and the optimal three-axis attitude pointing angle. Based on the optimal three-axis attitude pointing angle, the control subsystem controls the optical axis of the laser payload on the satellite to point towards the center of the target; at the same time, the data management subsystem controls the laser payload on the satellite to emit laser at the optimal calibration emission time; based on the position of the laser on the target, the ground system corrects the laser payload parameters and completes the calibration of the laser payload; finally, the control subsystem controls the satellite attitude to return to the normal zero attitude of the ground, and ends the calibration mission.
8. A fully autonomous spaceborne laser calibration system for ground-based targets according to claim 7, characterized in that: Based on the rough estimate of the calibration light emission time, the formula for calculating the start command transmission time T1 is as follows: T1=T0-T s Where T0 is a rough estimate of the calibration light emission time; T s For greater than T wt Any duration; T wt This refers to the satellite extrapolation time. The formula for calculating the second-order optimization time T2 in the control subsystem is: T2=T’-T D Where T' is the calibration light emission time, T D For satellite precision forecasting and maneuver stabilization duration.
9. A fully autonomous spaceborne laser calibration system for ground-based targets according to claim 7, characterized in that: The specific steps for the control subsystem to obtain the calibrated light output time are as follows: The first step is to calculate the satellite's orbit prediction data relative to the ground calibration field based on the extrapolation results of the first orbit. The second step is to use the orbital prediction data, the current laser installation matrix, and the latitude and longitude of the ground target to find all the moments during the satellite's on-orbit operation that meet the laser payload observation target constraints and to compile these moments into a time set. The third step is for the control subsystem to evaluate the maneuverability of the satellite at each time point in the time set and select the time point with the best maneuverability as the calibration time.
10. A fully autonomous spaceborne laser calibration system for ground-based targets according to claim 7, characterized in that: The control subsystem obtains the optimal calibration light emission time as follows: The first step is to calculate the optimal orbit prediction data of the satellite relative to the ground calibration field based on the second orbit extrapolation results; The second step is to use the optimal orbit prediction data, the current laser installation matrix and the latitude and longitude of the ground target to find all the moments during the satellite's on-orbit operation that meet the laser payload observation target constraints and to compile these moments into a time set. The third step is for the control subsystem to evaluate the maneuverability of the satellite at each time in the time set and select the time with the best maneuverability as the optimal calibration time. The control subsystem obtains the three-axis attitude pointing angles as follows: The first step is to calculate the satellite position at the optimal calibration light emission time based on the extrapolation results of the second orbit. The second step is to calculate the vector from the satellite to the center of the ground calibration field based on the satellite's position and the latitude and longitude of the ground target at the optimal calibration light output time. The third step involves the control subsystem calculating the three-axis attitude pointing angles based on the vector from the satellite to the center of the ground calibration field and the current laser installation matrix.