Method and system for autonomous computation and sun avoidance by laser communication terminals

Abstract

This invention provides a method and system for autonomous calculation and solar avoidance by a laser communication terminal, comprising: before the start of a laser communication mission, the satellite platform sends platform information for the current mission time period of the satellite and the target satellite to the laser terminal via the onboard bus; based on the received platform information, the laser terminal autonomously calculates the angle between the communication optical axis of the satellite and the target satellite and the solar vector during the mission period; during the calculation process before the mission starts, the laser terminal determines whether there is a moment during the mission when the angle is less than a preset safety threshold; if so, the laser terminal sends a warning message to the satellite platform; the satellite platform decides whether to execute the laser communication mission based on the warning message. This invention achieves autonomous solar outage avoidance onboard without real-time ground-based telemetry and control support by completely migrating the complex solar vector calculation and avoidance decision-making logic to the satellite and having the laser terminal perform it autonomously.

Description

Technical Field

[0001] This invention relates to the field of inter-satellite laser communication technology, specifically to a method and system for a laser communication terminal to autonomously calculate and avoid the sun. Background Technology

[0002] With the rapid development of space information networks, satellite laser communication has become the main transmission method for inter-satellite links (ISL) due to its advantages such as high bandwidth, anti-interference, and small size. However, because optical terminals are extremely sensitive to background light, "sun outage" or strong solar interference is a key bottleneck restricting the all-weather, 24 / 7 operation of laser communication. When the angle between the communication optical axis and the solar vector is less than a certain threshold (i.e., the sun exclusion angle, SEA), the intense solar background light will not only overwhelm the communication signal and cause link interruption, but in severe cases, the high-energy focused sunlight can directly burn out delicate optical sensors (such as ATP cameras and communication detectors), causing irreversible hardware damage.

[0003] To reliably and stably use inter-satellite lasers for high-speed data transmission and ensure the smooth operation of satellite missions, it is necessary to address the data loss problem caused by solar interference avoidance in laser communication. Specifically, during critical missions, the angle between the communication optical axis of the local satellite and the target satellite and the solar vector must be greater than a threshold angle. To solve this problem, the main technological evolution direction has shifted towards on-board autonomous processing. A search reveals that the existing technologies most similar to this solution mainly include:

[0004] Patent CN116112061A discloses a space routing method, apparatus, and storage medium based on solar outage avoidance, including: receiving user data; and obtaining the inter-satellite link topology matrix corresponding to all time periods at the current moment from multiple inter-satellite routing topology matrices. This method aims to solve the technical problem of ineffective and convenient space routing during solar outages, and differs from the prediction calculation method presented in this paper.

[0005] The patent with publication number CN113472418A discloses a method for inter-satellite link solar interference forecasting by a ground operation control system. This invention introduces a method that utilizes the spatial relationship between the sun, earth, and satellite, and considers the eclipse caused by the earth's shadow to complete the solar interference forecast. This method can quickly determine whether the inter-satellite link is affected by solar interference. It is a method for inter-satellite link solar interference forecasting by a ground operation control system. This invention is an on-board autonomous calculation, which is different from this patent.

[0006] The patent with publication number CN115865198A discloses an inter-satellite link solar outage avoidance and reset tracking method and system. This method adopts different avoidance strategies according to different link types to prevent the laser terminal from being directly exposed to sunlight. After solar outage avoidance, the laser terminal is moved to a specified angle to re-establish the inter-satellite link. This invention is applicable to the method of predicting and judging whether the mission is feasible after the laser terminal is turned on after receiving a satellite mission. This is different from the patent.

[0007] The patent with publication number CN114584198A discloses a method, device and medium for on-orbit autonomous avoidance of solar interference by a spaceborne laser communication device. The method includes, after the inter-satellite laser communication link is established, the attitude and orbit control subsystem continuously predicts the current time and the inter-satellite laser communication link vector and the solar incidence vector after T seconds. This invention is applicable to the method of predicting and judging whether the mission is executable after the satellite receives the mission and the laser terminal is turned on. This is different from the patent.

[0008] Patent CN113595618A discloses a method for predicting solar interference angle and solar interference time for satellite communication. This invention relates to a method for predicting solar interference angle and solar interference time for satellite communication. It uses a combination of ray tracing and background light power calculation to calculate the solar background light power reaching the CCD; compares the calculated solar background light power with the detection sensitivity of the CCD to determine the solar interference angle; and predicts the solar interference time of the inter-satellite laser link based on the formula for calculating the angle between sunlight and inter-satellite laser link and the solar interference threshold angle. This invention differs from the patent in that it determines the solar interference time by using the angle between the communication optical axis between the local satellite and the target satellite and the solar vector to be greater than the threshold angle.

[0009] In summary, given the problems of the existing technologies, researching a method and system for autonomous calculation and solar avoidance by laser communication terminals has become a critical task that urgently needs to be addressed. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for laser communication terminals to autonomously calculate and avoid the sun.

[0011] A method for autonomous calculation and solar avoidance by a laser communication terminal according to the present invention includes the following steps: Step S1: Before the laser communication mission begins, the satellite platform sends platform information for the current mission time period of both the satellite and the target satellite to the laser terminal via the onboard bus. Step S2: The laser terminal autonomously calculates the angle between the communication optical axis between the local satellite and the target satellite and the solar vector during the mission based on the received platform information. Step S3: During the calculation process before the task begins, the laser terminal determines whether the included angle is less than a preset safety threshold during the task. If so, the laser terminal sends a warning message to the satellite platform. Step S4: Based on the warning information, the satellite platform decides whether to execute the laser communication mission.

[0012] Preferably, in step S1, the platform information includes: the position, velocity, orbital parameters, and attitude parameters of the local satellite at the current time and during the mission period; the position and velocity information of the target satellite at the current time and during the mission period; and the mission duration of this laser communication.

[0013] Preferably, in step S2, the laser terminal autonomously calculates the angle between the communication optical axis and the solar vector between the local satellite and the target satellite during the mission based on the received platform information, including: step S21, calculating the position and velocity of the local satellite in the inertial coordinate system based on the platform information; step S22, calculating the first pointing angle of the communication link from the laser terminal on the local satellite to the laser terminal on the target satellite in the inertial coordinate system based on the position information of the local satellite and the target satellite; step S23, calculating the second pointing angle from the laser terminal on the local satellite to the solar vector in the inertial coordinate system; step S24, obtaining the actual pointing angle of the laser terminal by transforming the first pointing angle through a coordinate transformation chain from the inertial coordinate system to the final pointing angle of the laser terminal; and step S25, calculating the difference between the second pointing angle and the actual pointing angle to obtain the angle between the communication optical axis and the solar vector.

[0014] Preferably, in step S24, the coordinate transformation chain from the inertial coordinate system to the final pointing angle of the laser terminal includes: transformation from the inertial coordinate system to the satellite orbit coordinate system; transformation from the satellite orbit coordinate system to the satellite body coordinate system; transformation from the satellite body coordinate system to the laser terminal optical head cube mirror coordinate system; transformation from the laser terminal optical head cube mirror coordinate system to the laser terminal optical head body coordinate system; and transformation from the laser terminal optical head body coordinate system to the laser terminal optical head pointing angle.

[0015] Preferably, in step S4, the satellite platform decides whether to execute the laser communication task based on the warning information, including: step S41, the satellite platform assesses the interference risk indicated by the warning information and the current task priority; step S42, if it decides to execute the task, it sends an instruction to the laser terminal to make it enter the acquisition and tracking mode; step S43, if it decides to avoid the risk, it sends an instruction to the laser terminal to make it power off or enter the standby state.

[0016] This invention also provides a system for autonomous calculation and solar avoidance by a laser communication terminal. This system can be implemented by executing the steps of the method for autonomous calculation and solar avoidance by a laser communication terminal. That is, those skilled in the art can understand the method for autonomous calculation and solar avoidance by a laser communication terminal as a preferred embodiment of the system. The system includes: Module M1: Before the laser communication mission begins, the satellite platform sends platform information for the current mission time period of both the satellite and the target satellite to the laser terminal via the onboard bus. Module M2, the laser terminal autonomously calculates the angle between the communication optical axis between the local satellite and the target satellite and the solar vector during the mission based on the received platform information; In module M3, during the pre-mission calculation process, the laser terminal determines whether the included angle is less than a preset safety threshold during the mission. If so, the laser terminal sends a warning message to the satellite platform. Based on the warning information, the satellite platform, module M4, determines whether to execute the laser communication mission.

[0017] Compared with existing technologies, this invention has the following advantages: By completely migrating the complex solar vector calculation and avoidance decision-making logic to the satellite and having it autonomously completed by the laser terminal, this invention achieves autonomous solar interference avoidance on-board without real-time ground-based telemetry and control support. This method can predict the proximity risk between the communication optical axis and the solar vector in advance and accurately, and make intelligent mission decisions based on quantified risk parameters and preset strategies, thereby fundamentally avoiding data loss and communication interruptions caused by solar interference, and significantly improving the reliability and data integrity of the satellite laser communication link.

[0018] The on-board autonomous computing feature of this invention significantly reduces dependence on ground-based telemetry and control resources and enhances the autonomous operation capability of the satellite system. Furthermore, its support for a rapid collaborative forecasting and decision-making mechanism for multi-satellite clusters enables large-scale constellations to efficiently and flexibly schedule inter-satellite laser links, achieving an overall improvement from single-satellite reliability to system-level performance. This makes it suitable for next-generation satellite systems with high requirements for autonomy, reliability, and rapid response. Attached Figure Description

[0019] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 The flowchart illustrates a method for autonomous calculation and solar avoidance by a laser communication terminal, as provided by this invention.

[0020] Figure 2 This is a schematic diagram showing the angle between the communication optical axis of the laser terminal and the solar vector in this invention.

[0021] Explanation of reference numerals in the attached figures: 1—Orbit; 2—Angle between the communication optical axis and the solar vector; 3—Communication optical axis 4—Solar Vector 5—Laser Terminal Detailed Implementation The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0022] Figure 1 The flowchart of a method for autonomous calculation and solar avoidance by a laser communication terminal provided by the present invention is as follows: Figure 1 As shown, it includes the following steps: Step 1: Before the mission begins, the satellite platform sends the current platform information of the satellite and the target satellite, as well as the predicted value of the mission time period, to the laser terminal via the bus.

[0023] The platform information includes: the current position and velocity, orbital information, solar vector, and attitude parameters of the local satellite; predicted values ​​of the local satellite's position and velocity, orbital information, solar vector, and attitude parameters for the mission duration; estimated values ​​of the target satellite's current position and velocity; and mission duration. The target satellite's current position and velocity are reported from the ground at intervals, and the platform calculates them in real time based on this reported information.

[0024] Step 2: The laser terminal directly calculates the angle between the communication optical axis and the solar vector on the satellite based on the received platform information.

[0025] Specifically, the time interval for calculating the included angle during the mission is determined based on information from other platforms. It should be noted that the solar vector used is the solar vector under the orbital system.

[0026] In this embodiment, the forecasting method can be carried out autonomously on the satellite without ground support.

[0027] Furthermore, the specific steps for calculating the angle between the communication optical axis and the solar vector are as follows: Calculate the position and velocity of the local satellite in a specified inertial frame, where the specified inertial frame includes the J2000.0 or WGS-84 inertial frame; Calculate the link pointing angle between laser terminal 1 and laser terminal 2 in the specified inertial frame. Calculate the pointing angle from the laser terminal 1 (to which the link needs to be established) to the solar vector. ; Complete the coordinate transformation of the link pointing direction to obtain the pointing angle. The specific conversion process includes: specifying the inertial frame → orbital coordinate system → satellite body coordinate system → optical head cube mirror coordinate system → optical head body coordinate system → optical head pointing angle; calculate This yields the angle between the communication optical axis and the solar vector.

[0028] Step 3: If it is calculated before the task starts that there is an angle smaller than [a certain value] within the task time, [the following steps are taken]. At that moment, a forecast is sent to the satellite platform.

[0029] Specifically, Figure 2 This is a schematic diagram of the angle between the communication optical axis of the laser terminal and the solar vector. In the diagram: 1-orbit, 2-angle between the communication optical axis and the solar vector, 3-communication optical axis, 4-solar vector, 5-laser terminal. As shown in the figure, the laser terminal determines the angle between the communication optical axis of the local satellite and the target satellite and the solar vector during the mission based on platform information and predicted values, and compares it with the set angle threshold. If it is less than the threshold angle, it indicates that there is a solar outage that needs to be avoided, and the laser terminal reports the result to the platform.

[0030] Step 4: The satellite platform determines whether the mission should proceed based on the reported results and the importance of the mission. If the mission proceeds, it sends a command to put the laser terminal into acquisition and tracking mode. If the mission is terminated, it sends a command to shut down the laser terminal.

[0031] Specifically, the process of speculating whether a task is feasible includes: The satellite platform transmits platform information such as solar vector information and orbital information to the laser terminal via a bus; The laser terminal calculates the angle between the optical axis and the sun in real time based on the received solar vector information and orbit information; If in Time calculation The angle at any moment is less than Then, a warning message is sent to the satellite platform; Laser communication in Initiate evasion actions at all times, and refrain from communication during this period until... The angle at any time is greater than The laser communication system was restored to a working state and reported its status information to the satellite platform. Through the above steps, this embodiment can achieve rapid forecasting of multiple star clusters in a short time by calculating all stars within the visible range through inter-satellite information interaction.

[0032] This invention also provides a system for autonomous calculation and solar avoidance by a laser communication terminal. This system can be implemented by executing the steps of the method for autonomous calculation and solar avoidance by a laser communication terminal. That is, those skilled in the art can understand the method for autonomous calculation and solar avoidance by a laser communication terminal as a preferred embodiment of the system. The system includes: Module M1: Before the laser communication mission begins, the satellite platform sends platform information for the current mission time period of both the satellite and the target satellite to the laser terminal via the onboard bus. Module M2, the laser terminal autonomously calculates the angle between the communication optical axis between the local satellite and the target satellite and the solar vector during the mission based on the received platform information; In module M3, during the pre-mission calculation process, the laser terminal determines whether the included angle is less than a preset safety threshold during the mission. If so, the laser terminal sends a warning message to the satellite platform. Based on the warning information, the satellite platform, module M4, determines whether to execute the laser communication mission.

[0033] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0034] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for autonomous calculation and solar avoidance by a laser communication terminal, characterized in that, include: Step S1: Before the laser communication mission begins, the satellite platform sends platform information for the current mission time period of both the satellite and the target satellite to the laser terminal via the onboard bus. Step S2: The laser terminal autonomously calculates the angle between the communication optical axis between the local satellite and the target satellite and the solar vector during the mission based on the received platform information. Step S3: During the calculation process before the task begins, the laser terminal determines whether the included angle is less than a preset safety threshold during the task. If so, the laser terminal sends a warning message to the satellite platform. Step S4: Based on the warning information, the satellite platform decides whether to execute the laser communication mission.

2. The method for autonomous calculation and solar avoidance by a laser communication terminal according to claim 1, characterized in that, In step S1, the platform information includes: The satellite's position, velocity, orbital parameters, and attitude parameters at the current moment and during the mission period; The position and velocity information of the target star at the current moment and during the mission period; Duration of this laser communication mission.

3. The method for autonomous calculation and solar avoidance by a laser communication terminal according to claim 1, characterized in that, In step S2, the laser terminal autonomously calculates the angle between the communication optical axis of the local satellite and the target satellite and the solar vector during the mission, based on the received platform information, including: Step S21: Calculate the position and velocity of the local satellite in the inertial coordinate system based on the platform information; Step S22: Based on the position information of the local satellite and the target satellite, calculate the first pointing angle of the communication link from the laser terminal on the local satellite to the laser terminal on the target satellite in the inertial coordinate system. Step S23: Calculate the second pointing angle of the solar vector from the laser terminal on the local satellite in the inertial coordinate system; Step S24: The first pointing angle is transformed into the actual pointing angle of the laser terminal through a coordinate transformation chain from the inertial coordinate system to the final pointing angle of the laser terminal; Step S25: Calculate the difference between the second pointing angle and the actual pointing angle to obtain the angle between the communication optical axis and the solar vector.

4. The method for autonomous calculation and solar avoidance by a laser communication terminal according to claim 3, characterized in that, In step S24, the coordinate transformation chain from the inertial coordinate system to the final pointing angle of the laser terminal includes: Transform from the inertial coordinate system to the satellite orbit coordinate system; Transform from the satellite orbit coordinate system to the satellite body coordinate system; Transform from the satellite body coordinate system to the laser terminal optical head cube mirror coordinate system; Transform from the coordinate system of the cube mirror of the laser terminal optical head to the coordinate system of the laser terminal optical head body; Transform from the coordinate system of the laser terminal optical head body to the pointing angle of the laser terminal optical head.

5. The method for autonomous calculation and solar avoidance by a laser communication terminal according to claim 1, characterized in that, In step S4, the satellite platform decides whether to execute the laser communication mission based on the warning information, including: Step S41: The satellite platform assesses the interference risk indicated by the early warning information and the current mission priority; Step S42: If it is decided to execute the task, a command is sent to the laser terminal to make it enter the capture and tracking mode; Step S43: If it is decided to avoid the risk, a command is sent to the laser terminal to shut it down or put it into standby mode.

6. A system for autonomous calculation and solar avoidance in a laser communication terminal, characterized in that, include: Module M1: Before the laser communication mission begins, the satellite platform sends platform information for the current mission time period of both the satellite and the target satellite to the laser terminal via the onboard bus. Module M2, the laser terminal autonomously calculates the angle between the communication optical axis between the local satellite and the target satellite and the solar vector during the mission based on the received platform information; In module M3, during the pre-mission calculation process, the laser terminal determines whether the included angle is less than a preset safety threshold during the mission. If so, the laser terminal sends a warning message to the satellite platform. Based on the warning information, the satellite platform, module M4, decides whether to execute the laser communication mission.

7. A system for autonomous calculation and solar avoidance in a laser communication terminal according to claim 6, characterized in that, In module M1, the platform information includes: The satellite's position, velocity, orbital parameters, and attitude parameters at the current moment and during the mission period; The position and velocity information of the target star at the current moment and during the mission period; Duration of this laser communication mission.

8. A system for autonomous calculation and solar avoidance in a laser communication terminal according to claim 6, characterized in that, In module M2, the laser terminal autonomously calculates the angle between the communication optical axis of the local satellite and the target satellite and the solar vector during the mission, based on the received platform information, including: Module M21 calculates the position and velocity of the local satellite in the inertial coordinate system based on the platform information; Module M22 calculates the first pointing angle of the communication link from the laser terminal on the local satellite to the laser terminal on the target satellite in the inertial coordinate system based on the position information of the local satellite and the target satellite. Module M23 calculates the second pointing angle of the solar vector from the laser terminal on the local satellite in the inertial coordinate system; Module M24 obtains the actual pointing angle of the laser terminal by transforming the first pointing angle through a coordinate transformation chain from the inertial coordinate system to the final pointing angle of the laser terminal; Module M25 calculates the difference between the second pointing angle and the actual pointing angle to obtain the angle between the communication optical axis and the solar vector.

9. A system for autonomous calculation and solar avoidance in a laser communication terminal according to claim 8, characterized in that, In module M24, the coordinate transformation chain from the inertial coordinate system to the final pointing angle of the laser terminal includes: Transform from the inertial coordinate system to the satellite orbit coordinate system; Transform from the satellite orbit coordinate system to the satellite body coordinate system; Transform from the satellite body coordinate system to the laser terminal optical head cube mirror coordinate system; Transform from the coordinate system of the cube mirror of the laser terminal optical head to the coordinate system of the laser terminal optical head body; Transform from the coordinate system of the laser terminal optical head body to the pointing angle of the laser terminal optical head.

10. A system for autonomous calculation and solar avoidance in a laser communication terminal according to claim 6, characterized in that, In module M4, the satellite platform determines whether to execute the laser communication mission based on the warning information, including: Module M41, the satellite platform assesses the interference risk indicated by the early warning information and the current mission priority; If module M42 decides to execute a task, it sends a command to the laser terminal to put it into capture and tracking mode. If module M43 decides to avoid the risk, it sends a command to the laser terminal to shut it down or put it into standby mode.

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