An inter-satellite laser communication advance angle monitoring method and system

Abstract

This invention proposes a method and system for monitoring the lead angle in inter-satellite laser communication. In inter-satellite and satellite-to-ground laser communication, there is high-speed relative motion between the satellite and the target. Besides accurately tracking the target's position, the tracking system must also compensate for alignment errors caused by relative angular displacement during the beam's round-trip time. This means the output optical axis and the tracking optical axis need to deflect at a certain angle; this angle is the lead angle. This invention provides a method for calculating the magnitude of the inter-satellite lead angle and decomposes it into azimuth and elevation axes.

Description

Technical Field

[0001] This invention relates to the field of space laser communication, and in particular to a method and system for monitoring the lead angle of inter-satellite laser communication. Background Technology

[0002] Current calculations for inter-satellite lead pointing mainly employ... In this way.

[0003] In the formula, R is the relative position vector between the two stars, V is the relative velocity vector between the two stars, and C is the speed of light.

[0004] The method used is the mainstream calculation-leading pointing method, but actual measurements show that, since the initial R and V are in the J2000 inertial coordinate system, in this...

[0005] When converted to the laser terminal coordinate system, the attitude angular velocity will cause the calculated lead angle to be too large. Summary of the Invention

[0006] Existing methods for calculating the lead angle of laser terminals cannot compensate for errors caused by attitude angular velocity. This invention can compensate for these errors, enabling direct use in engineering models. The technical solution adopted is as follows:

[0007] A method for monitoring the lead angle of inter-satellite laser communication, characterized in that the method includes:

[0008] S1: Acquire the data parameters of the target star and the local star. The data parameters include the position vector and velocity vector of the target star, the position vector and velocity vector of the local star, the attitude information of the local star, and the coordinate system installation matrix of the laser terminal, and record the data parameters.

[0009] S2: Based on the acquired target satellite and local satellite data parameters, calculate the target aiming position vector of the target satellite and local satellite in the J2000 inertial coordinate system, use the attitude information of the local satellite to transform the target aiming position vector, and at the same time use the laser terminal coordinate system mounting matrix to transform the target aiming position vector into the laser terminal coordinate system.

[0010] S3: Convert the target aiming position vector of the laser terminal coordinate system into azimuth and elevation angles, and perform differential calculation with the azimuth and elevation angles of the previous moment to obtain the leading azimuth and leading elevation angles;

[0011] S4: Save the azimuth and elevation angles obtained at the current moment as a reference for the calculation at the next moment, and apply the calculated leading azimuth and leading elevation angles to the tracking and aiming system of the laser communication system to adjust the angle of the emitted optical axis to ensure that the beam can be accurately aimed at the target star;

[0012] S5: Continuously cycle through S1 to S4, monitor and adjust the leading forward azimuth and leading pitch angles in real time to adapt to the alignment error changes caused by the high-speed relative motion between satellites.

[0013] Preferably, S1 includes:

[0014] S11: Obtain the position and velocity information of the target satellite and the local satellite in the J2000 inertial coordinate system from the satellite platform broadcast;

[0015] S12: Use the attitude sensors deployed on the satellite to acquire the satellite's real-time attitude information and convert the attitude information into attitude quaternions;

[0016] S13: Retrieve the laser terminal coordinate system installation matrix from the database.

[0017] Preferably, S2 includes:

[0018] S21: Calculate the relative position vector between the target star and the local star: DR = R tar -R loc Where DR represents the relative position vector between the target star and the local star, and R... tar R represents the target aiming position vector of the target star in the J2000 inertial coordinate system. loc This represents the target aiming position vector of the local satellite in the J2000 inertial coordinate system. Using the attitude quaternion of the local satellite, the relative position vector DR is rotated from the J2000 inertial coordinate system to the local satellite coordinate system to obtain the target aiming position vector in the local satellite coordinate system.

[0019] S22: Use the laser terminal coordinate system mounting matrix to transform the target aiming position vector to the laser terminal coordinate system.

[0020] Preferably, S3 includes:

[0021] S31: Convert the target aiming position vector in the laser terminal coordinate system into azimuth and elevation angles, and Az = arctan2(x, y). Where Az represents the azimuth angle, E1 represents the elevation angle, x represents the horizontal component of the target aiming position vector in the laser terminal coordinate system, y represents the vertical component of the target aiming position vector in the laser terminal coordinate system, and z represents the radial component of the target aiming position vector in the laser terminal coordinate system.

[0022] S32: The obtained azimuth and elevation angles are compared with those of the previous moment using differential calculations to obtain the difference ΔAz of the target star's azimuth angle in the laser terminal coordinate system from the previous moment to the current moment, and the difference ΔE1 of the target star's elevation angle in the laser terminal coordinate system from the previous moment to the current moment. Finally, the leading azimuth and leading elevation angles are calculated, and... Where Az' represents the forward azimuth angle, E1' represents the forward pitch angle, and DR... sat denoted by , where c represents the target aiming position vector in the local coordinate system, and c represents the speed of light.

[0023] Preferably, S4 includes:

[0024] S41: Save the azimuth and elevation angles obtained at the current moment as a reference for the calculation at the next moment;

[0025] S42: By changing the angle of the emitted optical axis, the beam can be directed in advance to the expected future target position to compensate for the angular displacement caused by the high-speed relative motion between the target star and the local star.

[0026] An inter-satellite laser communication lead angle monitoring system, characterized in that the system comprises:

[0027] Data collection system: acquires data parameters of the target star and the local star, including the position and velocity vectors of the target star, the position and velocity vectors of the local star, the attitude information of the local star, and the coordinate system installation matrix of the laser terminal, and records the data parameters;

[0028] Vector conversion system: Based on the acquired target satellite and local satellite data parameters, the target aiming position vector of the target satellite and local satellite in the J2000 inertial coordinate system is calculated. The target aiming position vector is converted using the attitude information of the local satellite. At the same time, the target aiming position vector is converted to the laser terminal coordinate system using the laser terminal coordinate system mounting matrix.

[0029] Differential system: The target aiming position vector of the laser terminal coordinate system is converted into azimuth and elevation angles, and differential calculation is performed with the azimuth and elevation angles of the previous moment to obtain the leading azimuth and leading elevation angles;

[0030] Dynamic adjustment system: Saves the azimuth and elevation angles obtained at the current moment as a reference for the calculation of the next moment, and applies the calculated leading azimuth and leading elevation angles to the tracking and aiming system of the laser communication system to adjust the angle of the emitted optical axis to ensure that the beam can be accurately aimed at the target star;

[0031] The cyclic system continuously cycles through S1 to S4, monitoring and adjusting the leading-forward azimuth and leading-forward elevation angles in real time to adapt to the alignment error changes caused by the high-speed relative motion between satellites.

[0032] Preferably, the data collection system includes:

[0033] Velocity and position information acquisition system: Acquires the position and velocity information of the target satellite and the local satellite in the J2000 inertial coordinate system from the satellite platform broadcast;

[0034] Attitude sensing system: Uses attitude sensors deployed on the satellite to acquire the satellite's real-time attitude information and converts the attitude information into attitude quaternions;

[0035] Laser terminal coordinate system installation matrix acquisition system: retrieves the laser terminal coordinate system installation matrix from the database.

[0036] Preferably, the vector conversion system includes:

[0037] Target aiming position vector acquisition system: calculates the relative position vector between the target star and the local star: DR = R tar -R loc Where DR represents the relative position vector between the target star and the local star, and R... tar R represents the target aiming position vector of the target star in the J2000 inertial coordinate system. loc This represents the target aiming position vector of the local satellite in the J2000 inertial coordinate system. Using the attitude quaternion of the local satellite, the relative position vector DR is rotated from the J2000 inertial coordinate system to the local satellite coordinate system to obtain the target aiming position vector in the local satellite coordinate system.

[0038] Local satellite vector acquisition system: Uses a matrix installed in the laser terminal coordinate system to transform the target aiming position vector to the laser terminal coordinate system.

[0039] Local satellite vector acquisition system: Uses a matrix installed in the laser terminal coordinate system to transform the target aiming position vector to the laser terminal coordinate system.

[0040] Preferably, the differential system includes:

[0041] Azimuth and elevation angle acquisition system: This system converts the target aiming position vector in the laser terminal coordinate system into azimuth and elevation angles, where Az = arctan2(x, y). Where Az represents the azimuth angle, E1 represents the elevation angle, x represents the horizontal component of the target aiming position vector in the laser terminal coordinate system, y represents the vertical component of the target aiming position vector in the laser terminal coordinate system, and z represents the radial component of the target aiming position vector in the laser terminal coordinate system.

[0042] The lead angle acquisition system calculates the difference between the obtained azimuth and elevation angles and those from the previous moment, yielding the difference ΔAz in the azimuth angle of the target star in the laser terminal coordinate system from the previous moment to the current moment, and the difference ΔE1 in the elevation angle of the target star in the laser terminal coordinate system from the previous moment to the current moment. Finally, it calculates the lead azimuth and lead elevation angles. Where Az' represents the forward azimuth angle, E1' represents the forward pitch angle, and DR... satdenoted by , where c represents the target aiming position vector in the local coordinate system, and c represents the speed of light.

[0043] Preferably, the dynamic adjustment system includes:

[0044] Data storage system: Saves the azimuth and elevation angles obtained at the current moment as a reference for calculation at the next moment;

[0045] Compensation system: By changing the angle of the outgoing optical axis, the beam can be directed in advance to the expected future target position to compensate for the angular displacement caused by the high-speed relative motion between the target star and the local star.

[0046] The beneficial effects of this invention are: This invention can calculate the lead angle in real time with high accuracy, on the order of approximately 0.1 urad, to ensure stable laser communication link establishment. Attached Figure Description

[0047] Figure 1 This invention relates to a method for monitoring the lead angle of inter-satellite laser communication. Detailed Implementation

[0048] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0049] An embodiment of the present invention provides a method for monitoring the lead angle of inter-satellite laser communication, characterized in that the method includes:

[0050] S1: Acquire the data parameters of the target star and the local star. The data parameters include the position vector and velocity vector of the target star, the position vector and velocity vector of the local star, the attitude information of the local star, and the coordinate system installation matrix of the laser terminal, and record the data parameters.

[0051] S2: Based on the acquired target satellite and local satellite data parameters, calculate the target aiming position vector of the target satellite and local satellite in the J2000 inertial coordinate system, use the attitude information of the local satellite to transform the target aiming position vector, and at the same time use the laser terminal coordinate system mounting matrix to transform the target aiming position vector into the laser terminal coordinate system.

[0052] S3: Convert the target aiming position vector of the laser terminal coordinate system into azimuth and elevation angles, and perform differential calculation with the azimuth and elevation angles of the previous moment to obtain the leading azimuth and leading elevation angles;

[0053] S4: Save the azimuth and elevation angles obtained at the current moment as a reference for the calculation at the next moment, and apply the calculated leading azimuth and leading elevation angles to the tracking and aiming system of the laser communication system to adjust the angle of the emitted optical axis to ensure that the beam can be accurately aimed at the target star;

[0054] S5: Continuously cycle through S1 to S4, monitor and adjust the leading forward azimuth and leading pitch angles in real time to adapt to the alignment error changes caused by the high-speed relative motion between satellites.

[0055] The working principle and effect of the above technical solution are as follows: Using the position and velocity vectors of the target satellite and the local satellite, the target aiming position vector is calculated in the J2000 inertial coordinate system. The J2000 inertial coordinate system is a fixed, time-invariant reference system commonly used in astronomy and aerospace. The target aiming position vector is transformed from the J2000 inertial coordinate system to the local satellite's main coordinate system using the local satellite's attitude information. Then, using the laser terminal coordinate system mounting matrix, the target aiming position vector is further transformed to the laser terminal coordinate system. This yields the precise aiming position required by the laser communication system. The target aiming position vector in the laser terminal coordinate system is converted into azimuth and elevation angles. These two angles describe the direction the laser communication system needs to adjust. Difference calculations are performed with the azimuth and elevation angles from the previous moment to obtain the leading azimuth and leading elevation angles. The leading angles reflect the alignment error changes caused by the high-speed relative motion between satellites. The azimuth and elevation angles obtained at the current moment are saved as a reference for the calculation at the next moment. The calculated leading apex and leading elevation angles are applied to the tracking and aiming system of the laser communication system to adjust the angle of the output optical axis. This ensures that the beam can be accurately aligned with the target star even during high-speed relative motion between satellites. Steps S1 to S4 are continuously executed, with real-time monitoring and adjustment of the leading apex and leading elevation angles. This method adapts to alignment error changes caused by high-speed relative motion between satellites, ensuring the stability and reliability of laser communication. By monitoring and calculating the leading apex and leading elevation angles in real time, the angle of the output optical axis of the laser communication system can be precisely adjusted, ensuring accurate beam alignment with the target star. The inter-satellite laser communication leading angle monitoring method can adapt to alignment error changes caused by high-speed relative motion between satellites. Due to the extremely high speed of satellites in orbit and their constantly changing relative positions, traditional alignment methods may not meet the requirements. This method, through real-time monitoring and adjustment, ensures communication stability. This invention employs a cyclic monitoring method, enabling real-time acquisition of data parameters from both the target and home satellites, and rapid calculation of the leading apex and leading elevation angles. This real-time capability is crucial for responding to emergencies and ensuring communication continuity.

[0056] In one embodiment of the present invention, S1 includes:

[0057] S11: Obtain the position and velocity information of the target satellite and the local satellite in the J2000 inertial coordinate system from the satellite platform broadcast;

[0058] S12: Use the attitude sensors deployed on the satellite to acquire the satellite's real-time attitude information and convert the attitude information into attitude quaternions;

[0059] S13: Retrieve the laser terminal coordinate system installation matrix from the database.

[0060] The working principle and effect of the above technical solution are as follows: The satellite platform broadcasting system periodically transmits signals containing satellite position and velocity information. The receiving system captures these signals and extracts the position and velocity information of the target satellite and the local satellite in the J2000 inertial coordinate system. An attitude sensor is deployed on the local satellite to monitor its attitude changes in real time. The attitude sensor captures the local satellite's attitude data, including pitch, yaw, and roll angles. Through specific algorithms and calculation processes, this attitude data is converted into attitude quaternions. The laser terminal coordinate system installation matrix is ​​a matrix describing the installation position and orientation of the laser communication system relative to the local satellite. This matrix is ​​typically measured and calibrated during satellite manufacturing and integration and stored in a database. When needed, this matrix can be retrieved from the database for use in subsequent calculations and processing. The position and velocity information obtained from the satellite platform broadcast is generally highly accurate because this information is provided by a high-precision navigation and measurement system on the satellite. Furthermore, the satellite platform broadcasting system has global coverage capabilities, enabling the acquisition of the position and velocity information of both the target satellite and the local satellite regardless of their location. Using attitude quaternions to describe attitude information can avoid gimbal lock problems and improve the accuracy and stability of attitude description. Using an accurate laser terminal coordinate system installation matrix can reduce errors caused by inaccurate installation position and orientation, thereby improving the accuracy and stability of inter-satellite laser communication.

[0061] In one embodiment of the present invention, S2 includes:

[0062] S21: Calculate the relative position vector between the target star and the local star: DR = R tar -R loc Where DR represents the relative position vector between the target star and the local star, and R... tar R represents the target aiming position vector of the target star in the J2000 inertial coordinate system. loc This represents the target aiming position vector of the local satellite in the J2000 inertial coordinate system. Using the attitude quaternion of the local satellite, the relative position vector DR is rotated from the J2000 inertial coordinate system to the local satellite coordinate system to obtain the target aiming position vector in the local satellite coordinate system.

[0063] S22: Use the laser terminal coordinate system mounting matrix to transform the target aiming position vector to the laser terminal coordinate system.

[0064] The working principle and effect of the above technical solution are as follows: First, based on the position information of the target satellite and the local satellite in the J2000 inertial coordinate system obtained in S11, the relative position vector DR between them can be calculated. Next, the local satellite attitude quaternion obtained in S12 is used to rotate the relative position vector DR from the J2000 inertial coordinate system to the local satellite coordinate system. The rotation process involves quaternion multiplication and matrix transformation. The relative position vector DR is multiplied by the attitude quaternion to obtain the target aiming position vector in the local satellite coordinate system. According to the laser terminal coordinate system installation matrix obtained from the database in S13, the laser terminal coordinate system installation matrix describes the installation position and orientation of the laser communication system relative to the local satellite body. Using the laser terminal coordinate system installation matrix, the target aiming position vector in the local satellite coordinate system calculated in S21 is transformed to the laser terminal coordinate system. Step S21 obtains the relative position vector between the target satellite and the local satellite through precise mathematical calculations. Using attitude quaternions for coordinate rotation is an efficient and accurate mathematical method. Compared to traditional Euler angle representation, attitude quaternions avoid gimbal lock issues and are computationally simpler and more stable. Rotating the relative position vector from the J2000 inertial coordinate system to the local satellite coordinate system allows the laser communication system to more accurately aim at the target satellite. Step S22 uses the laser terminal coordinate system installation matrix to transform the target aiming position vector from the local satellite coordinate system to the laser terminal coordinate system. This transformation process ensures the accuracy of the aiming information, providing a foundation for precise aiming by the laser communication system. The laser terminal coordinate system installation matrix is ​​measured based on the actual installation position and orientation of the laser communication system, thus possessing strong adaptability. Regardless of the laser communication system's location on the local satellite, accurate coordinate transformation can be performed using the corresponding installation matrix.

[0065] In one embodiment of the present invention, S3 includes:

[0066] S31: Convert the target aiming position vector in the laser terminal coordinate system into azimuth and elevation angles, and Az = arctan2(x, y). Where Az represents the azimuth angle, E1 represents the elevation angle, x represents the horizontal component of the target aiming position vector in the laser terminal coordinate system, y represents the vertical component of the target aiming position vector in the laser terminal coordinate system, and z represents the radial component of the target aiming position vector in the laser terminal coordinate system.

[0067] S32: The obtained azimuth and elevation angles are compared with those of the previous moment using differential calculations to obtain the difference ΔAz of the target star's azimuth angle in the laser terminal coordinate system from the previous moment to the current moment, and the difference ΔE1 of the target star's elevation angle in the laser terminal coordinate system from the previous moment to the current moment. Finally, the leading azimuth and leading elevation angles are calculated, and... Where Az' represents the forward azimuth angle, E1' represents the forward pitch angle, and DR... sat denoted by , where c represents the target aiming position vector in the local coordinate system, and c represents the speed of light.

[0068] The working principle and effect of the above technical solution are as follows: In three-dimensional space, the position of a point can be represented by its coordinates in a certain coordinate system. For the target aiming position vector in the laser terminal coordinate system, it can be regarded as a point in three-dimensional space. Azimuth and elevation are two angles describing the direction of this point in space relative to a reference point. Azimuth usually represents the angle relative to a reference direction on the horizontal plane, while elevation represents the angle relative to the horizontal plane on the vertical plane. Through mathematical transformation, the target aiming position vector can be transformed from the laser terminal coordinate system to a spherical coordinate system with the laser terminal as the origin, thus obtaining the azimuth and elevation angles. At consecutive points in time, the azimuth and elevation angles of the target star in the laser terminal coordinate system will change. To predict the azimuth and elevation angles at a future moment, it is necessary to calculate the difference in azimuth and elevation angles from the previous moment to the current moment. Through these differences, the motion trend of the target star can be inferred, and the leading azimuth and leading elevation angles can be calculated accordingly. First, the azimuth and elevation angles of the previous and current moments are obtained. Then, the azimuth and elevation differences between these two moments are calculated. This typically involves simple subtraction. Next, based on parameters such as the target star's velocity and direction, and the time difference between the current and predicted moments, the leading azimuth and leading elevation angles are calculated. Converting the target aiming position vector in the laser terminal coordinate system into azimuth and elevation angles makes the target star's position information more intuitive and easier to understand. This representation is more in line with human spatial cognition habits. The azimuth and elevation angles directly correspond to the aiming direction of the laser communication system; therefore, the converted information can be directly used to guide the aiming operation of the laser communication system. The converted azimuth and elevation angle information can be used for subsequent calculations and analysis, providing strong support for precise aiming and stable communication in inter-satellite laser communication. The difference between the azimuth and elevation angles obtained through differential calculation can reflect the target star's motion relative to the laser terminal in real time. This helps to adjust the aiming direction of the laser communication system in a timely manner, ensuring the stability and accuracy of communication. Using the difference obtained through differential calculation, the azimuth and elevation angles of the target star at a future moment can be predicted. This provides a basis for advanced aiming in laser communication systems, helping to adjust the aiming direction in advance and ensure the continuity of communication.

[0069] In one embodiment of the present invention, S4 includes:

[0070] S41: Save the azimuth and elevation angles obtained at the current moment as a reference for the calculation at the next moment;

[0071] S42: By changing the angle of the emitted optical axis, the beam can be directed in advance to the expected future target position to compensate for the angular displacement caused by the high-speed relative motion between the target star and the local star.

[0072] The working principle and effect of the above technical solution are as follows: The azimuth and elevation angles calculated at the current moment are saved. These two angle values ​​represent the precise position of the target star that the laser communication system needs to point to in the laser terminal coordinate system at the current time. Saving these values ​​serves as a reference for differential calculations at the next moment, thereby enabling the prediction and adjustment of the laser communication system's aiming direction. Saving the current azimuth and elevation angles allows for differential calculations at the next moment to determine the motion of the target star relative to the laser terminal. By continuously saving and comparing the azimuth and elevation angles at different times, the future motion trend of the target star can be predicted, thus achieving advanced aiming. Since both the target star and the local star are constantly moving, their relative positions are constantly changing. To ensure that the laser communication system can stably point to the target star and maintain the communication link, the angle of the outgoing optical axis needs to be continuously adjusted so that it can point to the expected future target position in advance. The system calculates the advanced azimuth and elevation angles based on the current azimuth and elevation angles and the relative motion of the target star and the local star. Then, by adjusting the output optical axis of the laser communication system to point according to the calculated lead angle, the angular displacement caused by relative motion is compensated. Adjusting the angle of the output optical axis compensates for the angular displacement caused by the high-speed relative motion between the target star and the local star, ensuring that the laser communication system can stably point at the target star. Lead-ahead aiming technology ensures that the laser communication system can maintain a stable communication link throughout the relative motion between the target star and the local star, improving the reliability and stability of communication.

[0073] An embodiment of the present invention provides an inter-satellite laser communication lead angle monitoring system, characterized in that the system comprises:

[0074] Data collection system: acquires data parameters of the target star and the local star, including the position and velocity vectors of the target star, the position and velocity vectors of the local star, the attitude information of the local star, and the coordinate system installation matrix of the laser terminal, and records the data parameters;

[0075] Vector conversion system: Based on the acquired target satellite and local satellite data parameters, the target aiming position vector of the target satellite and local satellite in the J2000 inertial coordinate system is calculated. The target aiming position vector is converted using the attitude information of the local satellite. At the same time, the target aiming position vector is converted to the laser terminal coordinate system using the laser terminal coordinate system mounting matrix.

[0076] Differential system: The target aiming position vector of the laser terminal coordinate system is converted into azimuth and elevation angles, and differential calculation is performed with the azimuth and elevation angles of the previous moment to obtain the leading azimuth and leading elevation angles;

[0077] Dynamic adjustment system: Saves the azimuth and elevation angles obtained at the current moment as a reference for the calculation of the next moment, and applies the calculated leading azimuth and leading elevation angles to the tracking and aiming system of the laser communication system to adjust the angle of the emitted optical axis to ensure that the beam can be accurately aimed at the target star;

[0078] The cyclic system continuously cycles through S1 to S4, monitoring and adjusting the leading-forward azimuth and leading-forward elevation angles in real time to adapt to the alignment error changes caused by the high-speed relative motion between satellites.

[0079] The working principle and effect of the above technical solution are as follows: Using the position and velocity vectors of the target satellite and the local satellite, the target aiming position vector is calculated in the J2000 inertial coordinate system. The J2000 inertial coordinate system is a fixed, time-invariant reference system commonly used in astronomy and aerospace. The target aiming position vector is transformed from the J2000 inertial coordinate system to the local satellite's main coordinate system using the local satellite's attitude information. Then, using the laser terminal coordinate system mounting matrix, the target aiming position vector is further transformed to the laser terminal coordinate system. This yields the precise aiming position required by the laser communication system. The target aiming position vector in the laser terminal coordinate system is converted into azimuth and elevation angles. These two angles describe the direction the laser communication system needs to adjust. Difference calculations are performed with the azimuth and elevation angles from the previous moment to obtain the leading azimuth and leading elevation angles. The leading angles reflect the alignment error changes caused by the high-speed relative motion between satellites. The azimuth and elevation angles obtained at the current moment are saved as a reference for the calculation at the next moment. The calculated leading apex and leading elevation angles are applied to the tracking and aiming system of the laser communication system to adjust the angle of the output optical axis. This ensures that the beam can be accurately aligned with the target star even during high-speed relative motion between satellites. Steps S1 to S4 are continuously executed, with real-time monitoring and adjustment of the leading apex and leading elevation angles. This method adapts to alignment error changes caused by high-speed relative motion between satellites, ensuring the stability and reliability of laser communication. By monitoring and calculating the leading apex and leading elevation angles in real time, the angle of the output optical axis of the laser communication system can be precisely adjusted, ensuring accurate beam alignment with the target star. The inter-satellite laser communication leading angle monitoring method can adapt to alignment error changes caused by high-speed relative motion between satellites. Due to the extremely high speed of satellites in orbit and their constantly changing relative positions, traditional alignment methods may not meet the requirements. This method, through real-time monitoring and adjustment, ensures communication stability. This invention employs a cyclic monitoring method, enabling real-time acquisition of data parameters from both the target and home satellites, and rapid calculation of the leading apex and leading elevation angles. This real-time capability is crucial for responding to emergencies and ensuring communication continuity.

[0080] In one embodiment of the present invention, the data collection system includes:

[0081] Velocity and position information acquisition system: Acquires the position and velocity information of the target satellite and the local satellite in the J2000 inertial coordinate system from the satellite platform broadcast;

[0082] Attitude sensing system: Uses attitude sensors deployed on the satellite to acquire the satellite's real-time attitude information and converts the attitude information into attitude quaternions;

[0083] Laser terminal coordinate system installation matrix acquisition system: retrieves the laser terminal coordinate system installation matrix from the database.

[0084] The working principle and effect of the above technical solution are as follows: The satellite platform broadcasting system periodically transmits signals containing satellite position and velocity information. The receiving system captures these signals and extracts the position and velocity information of the target satellite and the local satellite in the J2000 inertial coordinate system. An attitude sensor is deployed on the local satellite to monitor its attitude changes in real time. The attitude sensor captures the local satellite's attitude data, including pitch, yaw, and roll angles. Through specific algorithms and calculation processes, this attitude data is converted into attitude quaternions. The laser terminal coordinate system installation matrix is ​​a matrix describing the installation position and orientation of the laser communication system relative to the local satellite. This matrix is ​​typically measured and calibrated during satellite manufacturing and integration and stored in a database. When needed, this matrix can be retrieved from the database for use in subsequent calculations and processing. The position and velocity information obtained from the satellite platform broadcast is generally highly accurate because this information is provided by a high-precision navigation and measurement system on the satellite. Furthermore, the satellite platform broadcasting system has global coverage capabilities, enabling the acquisition of the position and velocity information of both the target satellite and the local satellite regardless of their location. Using attitude quaternions to describe attitude information can avoid gimbal lock problems and improve the accuracy and stability of attitude description. Using an accurate laser terminal coordinate system installation matrix can reduce errors caused by inaccurate installation position and orientation, thereby improving the accuracy and stability of inter-satellite laser communication.

[0085] In one embodiment of the present invention, the vector conversion system includes:

[0086] Target aiming position vector acquisition system: calculates the relative position vector between the target star and the local star: DR = R tar -R loc Where DR represents the relative position vector between the target star and the local star, and R... tar R represents the target aiming position vector of the target star in the J2000 inertial coordinate system. loc This represents the target aiming position vector of the local satellite in the J2000 inertial coordinate system. Using the attitude quaternion of the local satellite, the relative position vector DR is rotated from the J2000 inertial coordinate system to the local satellite coordinate system to obtain the target aiming position vector in the local satellite coordinate system.

[0087] Local satellite vector acquisition system: Uses a matrix installed in the laser terminal coordinate system to transform the target aiming position vector to the laser terminal coordinate system.

[0088] Local satellite vector acquisition system: Uses a matrix installed in the laser terminal coordinate system to transform the target aiming position vector to the laser terminal coordinate system.

[0089] The working principle and effect of the above technical solution are as follows: First, based on the position information of the target satellite and the local satellite in the J2000 inertial coordinate system obtained in S11, the relative position vector DR between them can be calculated. Next, the local satellite attitude quaternion obtained in S12 is used to rotate the relative position vector DR from the J2000 inertial coordinate system to the local satellite coordinate system. The rotation process involves quaternion multiplication and matrix transformation. The relative position vector DR is multiplied by the attitude quaternion to obtain the target aiming position vector in the local satellite coordinate system. According to the laser terminal coordinate system installation matrix obtained from the database in S13, the laser terminal coordinate system installation matrix describes the installation position and orientation of the laser communication system relative to the local satellite body. Using the laser terminal coordinate system installation matrix, the target aiming position vector in the local satellite coordinate system calculated in S21 is transformed to the laser terminal coordinate system. Step S21 obtains the relative position vector between the target satellite and the local satellite through precise mathematical calculations. Using attitude quaternions for coordinate rotation is an efficient and accurate mathematical method. Compared to traditional Euler angle representation, attitude quaternions avoid gimbal lock issues and are computationally simpler and more stable. Rotating the relative position vector from the J2000 inertial coordinate system to the local satellite coordinate system allows the laser communication system to more accurately aim at the target satellite. Step S22 uses the laser terminal coordinate system installation matrix to transform the target aiming position vector from the local satellite coordinate system to the laser terminal coordinate system. This transformation process ensures the accuracy of the aiming information, providing a foundation for precise aiming by the laser communication system. The laser terminal coordinate system installation matrix is ​​measured based on the actual installation position and orientation of the laser communication system, thus possessing strong adaptability. Regardless of the laser communication system's location on the local satellite, accurate coordinate transformation can be performed using the corresponding installation matrix.

[0090] In one embodiment of the present invention, the differential system includes:

[0091] Azimuth and elevation angle acquisition system: This system converts the target aiming position vector in the laser terminal coordinate system into azimuth and elevation angles, where Az = arctan2(x, y). Where Az represents the azimuth angle, E1 represents the elevation angle, x represents the horizontal component of the target aiming position vector in the laser terminal coordinate system, y represents the vertical component of the target aiming position vector in the laser terminal coordinate system, and z represents the radial component of the target aiming position vector in the laser terminal coordinate system.

[0092] The lead angle acquisition system calculates the difference between the obtained azimuth and elevation angles and those from the previous moment, yielding the difference ΔAz in the azimuth angle of the target star in the laser terminal coordinate system from the previous moment to the current moment, and the difference ΔE1 in the elevation angle of the target star in the laser terminal coordinate system from the previous moment to the current moment. Finally, it calculates the lead azimuth and lead elevation angles. Where Az' represents the forward azimuth angle, E1' represents the forward pitch angle, and DR... sat denoted by , where c represents the target aiming position vector in the local coordinate system, and c represents the speed of light.

[0093] The working principle and effect of the above technical solution are as follows: In three-dimensional space, the position of a point can be represented by its coordinates in a certain coordinate system. For the target aiming position vector in the laser terminal coordinate system, it can be regarded as a point in three-dimensional space. Azimuth and elevation are two angles describing the direction of this point in space relative to a reference point. Azimuth usually represents the angle relative to a reference direction on the horizontal plane, while elevation represents the angle relative to the horizontal plane on the vertical plane. Through mathematical transformation, the target aiming position vector can be transformed from the laser terminal coordinate system to a spherical coordinate system with the laser terminal as the origin, thus obtaining the azimuth and elevation angles. At consecutive points in time, the azimuth and elevation angles of the target star in the laser terminal coordinate system will change. To predict the azimuth and elevation angles at a future moment, it is necessary to calculate the difference in azimuth and elevation angles from the previous moment to the current moment. Through these differences, the motion trend of the target star can be inferred, and the leading azimuth and leading elevation angles can be calculated accordingly. First, the azimuth and elevation angles of the previous and current moments are obtained. Then, the azimuth and elevation differences between these two moments are calculated. This typically involves simple subtraction. Next, based on parameters such as the target star's velocity and direction, and the time difference between the current and predicted moments, the leading azimuth and leading elevation angles are calculated. Converting the target aiming position vector in the laser terminal coordinate system into azimuth and elevation angles makes the target star's position information more intuitive and easier to understand. This representation is more in line with human spatial cognition habits. The azimuth and elevation angles directly correspond to the aiming direction of the laser communication system; therefore, the converted information can be directly used to guide the aiming operation of the laser communication system. The converted azimuth and elevation angle information can be used for subsequent calculations and analysis, providing strong support for precise aiming and stable communication in inter-satellite laser communication. The difference between the azimuth and elevation angles obtained through differential calculation can reflect the target star's motion relative to the laser terminal in real time. This helps to adjust the aiming direction of the laser communication system in a timely manner, ensuring the stability and accuracy of communication. Using the difference obtained through differential calculation, the azimuth and elevation angles of the target star at a future moment can be predicted. This provides a basis for advanced aiming in laser communication systems, helping to adjust the aiming direction in advance and ensure the continuity of communication.

[0094] In one embodiment of the present invention, the dynamic adjustment system includes:

[0095] Data storage system: Saves the azimuth and elevation angles obtained at the current moment as a reference for calculation at the next moment;

[0096] Compensation system: By changing the angle of the outgoing optical axis, the beam can be directed in advance to the expected future target position to compensate for the angular displacement caused by the high-speed relative motion between the target star and the local star.

[0097] Since light beams are distorted when passing through atmospheric turbulence, this invention also utilizes an adaptive optics system to compensate for the wavefront distortion caused by atmospheric turbulence in real time. The technical solution adopted is as follows:

[0098] Step 1: Measure the wavefront distortion information of the light beam using a wavefront sensor. The wavefront distortion information is represented by a distortion function, which is obtained using the following formula:

[0099] S(r,t)=a(r,t)+n(r,t)

[0100] Where S(r,t) represents the measured wavefront distortion function, a(r,t) represents the actual wavefront distortion, n(r,t) represents the measurement noise, r represents the spatial position vector of the wave, and t represents the measurement time;

[0101] Step 2: Based on the measured wavefront distortion, reconstruct the wavefront distortion using Zernike polynomials. Zernike polynomials are a commonly used set of orthogonal polynomials suitable for wavefront fitting, and the calculation formula is as follows:

[0102]

[0103] Where e(r,t) represents the reconstruction function, Zi(r) represents the i-th Zernike polynomial, and ai(t) represents the corresponding Zernike coefficient;

[0104] Step 3: Based on the reconstructed wavefront distortion, calculate the control commands for the adaptive optics system, using the following formula:

[0105]

[0106] Where C(r,t) represents the compensation function derived from the adaptive optics system, α represents the compensation factor, and the value range of α is (0,1].

[0107] Step 4: The received control commands are transmitted to the adaptive optics system, which makes adjustments to correct wavefront distortion. The calculation formula is as follows:

[0108] u(r,t)=S(r,t)-C(r,t)

[0109] Where u(r, t) represents the corrected wavefront function;

[0110] Step 4: Repeat steps 1 through 3 at the next moment to adapt to the dynamically changing wavefront distortion.

[0111] The working principle and effect of the above technical solution are as follows: Wavefront distortion information of the light beam is measured in real time using a wavefront sensor. The wavefront sensor can capture and measure the phase distribution of the beam's wavefront, thereby obtaining detailed information about the wavefront distortion. Based on the measured wavefront distortion information, the wavefront distortion is mathematically reconstructed using Zernike polynomials. Zernike polynomials are a mathematical tool used to describe wavefront distortion, which can decompose complex wavefront distortion into a series of simple patterns. By fitting the measured wavefront distortion data, the coefficients of the Zernike polynomials can be obtained, thereby reconstructing the mathematical model of the wavefront distortion. Based on the reconstructed wavefront distortion mathematical model, control commands for the adaptive optics system are calculated. The adaptive optics system includes a wavefront corrector and a controller. The controller calculates the shape or phase distribution that the wavefront corrector needs to adjust to compensate for the wavefront distortion based on the reconstructed wavefront distortion mathematical model. The control commands are sent to the wavefront corrector for execution through the controller. Since atmospheric turbulence is dynamic, wavefront distortion also changes over time. Therefore, the process of measurement, reconstruction, and control command calculation needs to be repeated continuously to track and compensate for wavefront distortion in real time. This iterative approach ensures the continuous and effective operation of the adaptive optics system. The system measures and compensates for wavefront distortion caused by atmospheric turbulence in real time, significantly improving beam quality. This includes improving beam focusing performance and reducing defocusing and aberrations. In astronomical observation, adaptive optics significantly enhances the sharpness of astronomical images, allowing observers to more accurately observe the details and structure of celestial objects. The system tracks and adapts to dynamic changes in atmospheric turbulence in real time, ensuring beam stability and accuracy. This helps reduce systematic errors and uncertainties caused by wavefront distortion. By compensating for wavefront distortion in real time, the adaptive optics system enhances the robustness of the entire system, maintaining stable performance under various environmental conditions.

[0112] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An inter-satellite laser communication lead angle monitoring method, characterized in that, The method includes: S1: Acquire the data parameters of the target star and the local star. The data parameters include the position vector and velocity vector of the target star, the position vector and velocity vector of the local star, the attitude information of the local star, and the coordinate system installation matrix of the laser terminal, and record the data parameters. S2: Based on the acquired target satellite and local satellite data parameters, calculate the target aiming position vector of the target satellite and local satellite in the J2000 inertial coordinate system, use the attitude information of the local satellite to transform the target aiming position vector, and at the same time use the laser terminal coordinate system mounting matrix to transform the target aiming position vector into the laser terminal coordinate system. S3: Convert the target aiming position vector of the laser terminal coordinate system into azimuth and elevation angles, and perform differential calculation with the azimuth and elevation angles of the previous moment to obtain the leading azimuth and leading elevation angles; S4: Save the azimuth and elevation angles obtained at the current moment as a reference for the calculation at the next moment, and apply the calculated leading azimuth and leading elevation angles to the tracking and aiming system of the laser communication system to adjust the angle of the emitted optical axis to ensure that the beam can be accurately aimed at the target star; S5: Continuously cycle through S1 to S4, monitor and adjust the leading forward azimuth and leading pitch angles in real time to adapt to the alignment error changes caused by the high-speed relative motion between satellites.

2. The method of claim 1, wherein the method further comprises: S1 includes: S11: Obtain the position and velocity information of the target satellite and the local satellite in the J2000 inertial coordinate system from the satellite platform broadcast; S12: Use the attitude sensors deployed on the satellite to acquire the satellite's real-time attitude information and convert the attitude information into attitude quaternions; S13: Retrieve the laser terminal coordinate system installation matrix from the database.

3. The method for monitoring the lead angle of inter-satellite laser communication according to claim 1, characterized in that, S2 includes: S21: Calculate the relative position vector between the target star and the local star: DR = R tar -R loc Where DR represents the relative position vector between the target star and the local star, and R... tar R represents the target aiming position vector of the target star in the J2000 inertial coordinate system. loc This represents the target aiming position vector of the local satellite in the J2000 inertial coordinate system. Using the attitude quaternion of the local satellite, the relative position vector DR is rotated from the J2000 inertial coordinate system to the local satellite coordinate system to obtain the target aiming position vector in the local satellite coordinate system. S22: Use the laser terminal coordinate system mounting matrix to transform the target aiming position vector to the laser terminal coordinate system.

4. The method for monitoring the lead angle of inter-satellite laser communication according to claim 1, characterized in that, S3 includes: S31: Convert the target aiming position vector in the laser terminal coordinate system into azimuth and elevation angles, and Az = arctan2(x, y). Where Az represents the azimuth angle, E1 represents the elevation angle, x represents the horizontal component of the target aiming position vector in the laser terminal coordinate system, y represents the vertical component of the target aiming position vector in the laser terminal coordinate system, and z represents the radial component of the target aiming position vector in the laser terminal coordinate system. S32: The obtained azimuth and elevation angles are compared with those of the previous moment using differential calculations to obtain the difference ΔAz of the target star's azimuth angle in the laser terminal coordinate system from the previous moment to the current moment, and the difference ΔE1 of the target star's elevation angle in the laser terminal coordinate system from the previous moment to the current moment. Finally, the leading azimuth and leading elevation angles are calculated, and... Where Az' represents the forward azimuth angle, E1' represents the forward pitch angle, and DR... sat denoted by , where c represents the target aiming position vector in the local coordinate system, and c represents the speed of light.

5. The method of claim 1, wherein the method further comprises: S4 includes: S41: Save the azimuth and elevation angles obtained at the current moment as a reference for the calculation at the next moment; S42: By changing the angle of the emitted optical axis, the beam can be directed in advance to the expected future target position to compensate for the angular displacement caused by the high-speed relative motion between the target star and the local star.

6. An inter-satellite laser communication lead angle monitoring system, characterized in that, The system includes: Data collection system: acquires data parameters of the target star and the local star, including the position and velocity vectors of the target star, the position and velocity vectors of the local star, the attitude information of the local star, and the coordinate system installation matrix of the laser terminal, and records the data parameters; Vector conversion system: Based on the acquired target satellite and local satellite data parameters, the target aiming position vector of the target satellite and local satellite in the J2000 inertial coordinate system is calculated. The target aiming position vector is converted using the attitude information of the local satellite. At the same time, the target aiming position vector is converted to the laser terminal coordinate system using the laser terminal coordinate system mounting matrix. Differential system: The target aiming position vector of the laser terminal coordinate system is converted into azimuth and elevation angles, and differential calculation is performed with the azimuth and elevation angles of the previous moment to obtain the leading azimuth and leading elevation angles; Dynamic adjustment system: Saves the azimuth and elevation angles obtained at the current moment as a reference for the calculation of the next moment, and applies the calculated leading azimuth and leading elevation angles to the tracking and aiming system of the laser communication system to adjust the angle of the emitted optical axis to ensure that the beam can be accurately aimed at the target star; The cyclic system continuously cycles through S1 to S4, monitoring and adjusting the leading-forward azimuth and leading-forward elevation angles in real time to adapt to the alignment error changes caused by the high-speed relative motion between satellites.

7. The inter-satellite laser communication lead angle monitoring system according to claim 6, characterized in that, The data collection system includes: Velocity and position information acquisition system: Acquires the position and velocity information of the target satellite and the local satellite in the J2000 inertial coordinate system from the satellite platform broadcast; Attitude sensing system: Uses attitude sensors deployed on the satellite to acquire the satellite's real-time attitude information and converts the attitude information into attitude quaternions; Laser terminal coordinate system installation matrix acquisition system: Retrieves the laser terminal coordinate system installation matrix from the database.

8. The system for monitoring the lead angle of the inter-satellite laser communication according to claim 6, wherein, The vector conversion system includes: Target aiming position vector acquisition system: calculates the relative position vector between the target star and the local star: DR = R tar -R loc Where DR represents the relative position vector between the target star and the local star, and R... tar R represents the target aiming position vector of the target star in the J2000 inertial coordinate system. loc This represents the target aiming position vector of the local satellite in the J2000 inertial coordinate system. Using the attitude quaternion of the local satellite, the relative position vector DR is rotated from the J2000 inertial coordinate system to the local satellite coordinate system to obtain the target aiming position vector in the local satellite coordinate system. Local satellite vector acquisition system: Uses a matrix installed in the laser terminal coordinate system to transform the target aiming position vector to the laser terminal coordinate system.

9. The inter-satellite laser communication lead angle monitoring system according to claim 6, characterized in that, The differential system includes: Azimuth and elevation angle acquisition system: This system converts the target aiming position vector in the laser terminal coordinate system into azimuth and elevation angles, where Az = arctan2(x, y). Where Az is the azimuth angle, E1 is the elevation angle, x is the horizontal component of the target aiming position vector in the laser terminal coordinate system, y is the vertical component of the target aiming position vector in the laser terminal coordinate system, and z is the radial component of the target aiming position vector in the laser terminal coordinate system. The lead angle acquisition system calculates the difference between the obtained azimuth and elevation angles and those from the previous moment, yielding the difference ΔAz in the azimuth angle of the target star in the laser terminal coordinate system from the previous moment to the current moment, and the difference ΔE1 in the elevation angle of the target star in the laser terminal coordinate system from the previous moment to the current moment. Finally, it calculates the lead azimuth and lead elevation angles. Where Az' represents the forward azimuth angle, E1' represents the forward pitch angle, and DR... sat denoted by , where c represents the target aiming position vector in the local coordinate system, and c represents the speed of light.

10. The system for monitoring the lead angle of the intersatellite laser communication according to claim 6, wherein, The dynamic adjustment system includes: Data storage system: Saves the azimuth and elevation angles obtained at the current moment as a reference for calculation at the next moment; Compensation system: By changing the angle of the outgoing optical axis, the beam can be directed in advance to the expected future target position to compensate for the angular displacement caused by the high-speed relative motion between the target star and the local star.

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