Composite early acquisition system and method in moon-earth laser communication link tracking

Abstract

This invention provides a composite advance aiming system and method for tracking a lunar-Earth laser communication link, belonging to the field of deep space laser communication technology. The system includes a receive delay compensation module, a platform vibration compensation module, a transmit delay compensation module, a composite aiming calculation module, and an aiming execution mechanism. The receive delay compensation module extrapolates the current position of the target based on the transmission delay of the target's transmitted signal; the platform vibration compensation module monitors and predicts the optical axis offset caused by vibration of the local platform; the transmit delay compensation module predicts the position of the target terminal when the signal arrives. The composite aiming calculation module integrates the three compensations to calculate the composite advance aiming angle. This invention comprehensively considers three factors—receive delay, platform vibration, and transmit delay—to achieve precise advance aiming, effectively solving the pointing deviation problem in long-distance lunar-Earth laser communication, ensuring that the laser signal accurately reaches the target terminal, and meeting the high-precision requirements of lunar-Earth laser communication link tracking.

Description

Technical Field

[0001] This invention relates to the field of laser communication engineering technology, and more specifically, to a composite advance aiming system and method for tracking lunar-Earth laser communication links. Background Technology

[0002] With the deepening of deep space exploration missions and the increasing frequency of lunar exploration activities, the demand for high-speed data transmission between the Earth and the Moon is becoming more and more urgent. Compared with traditional microwave communication, laser communication has significant advantages such as high transmission rate, strong anti-interference ability, small equipment size, and low power consumption, and has become an important development direction for deep space communication.

[0003] The lunar-Earth laser communication system requires establishing a stable optical link between the lunar orbiting laser terminal and the ground station. Given the distance between the Moon and Earth is approximately 380,000 kilometers, the one-way transmission delay of the optical signal is about 1.28 seconds, and the two-way delay is about 2.56 seconds. Under such long transmission distances and high latency conditions, achieving accurate link tracking is crucial to ensuring communication quality.

[0004] In existing technologies, the tracking and aiming methods of laser communication systems mainly employ the following approaches: The first method is based on direct tracking of the received signal, that is, determining the transmission direction based on the direction of the received beacon light from the other party. However, due to the significant signal transmission delay between the Earth and the Moon, the received signal reflects the past position of the other party's terminal, not its current position. Directly using this as the transmission direction will lead to significant pointing errors.

[0005] The second method is prediction tracking based on ephemeris tables, which predicts the position of the other terminal using pre-calculated orbital data. However, this method is difficult to handle dynamic situations such as orbital maneuvers and attitude changes, and the accumulated error increases over time.

[0006] The third approach is a composite tracking system that combines open-loop and closed-loop methods. However, existing solutions typically only consider single or partial delay factors and fail to fully consider all factors that affect aiming accuracy.

[0007] Furthermore, lunar orbiting spacecraft experience continuous micro-vibrations on their platform due to factors such as the operation of their attitude control system, solar panel vibration, and thermal deformation. These vibrations directly affect the pointing accuracy of the laser terminal. While ground stations are relatively stable, they are also affected by factors such as atmospheric turbulence and mechanical vibration.

[0008] Therefore, in lunar-Earth laser communication link tracking, how to comprehensively consider multiple factors such as signal transmission delay, platform vibration, and transmission delay to achieve accurate early aiming is a technical problem that urgently needs to be solved. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the purpose of this invention is to provide a composite advance aiming method and system for tracking lunar-Earth laser communication links.

[0010] A composite advance aiming method for tracking a lunar-Earth laser communication link according to the present invention includes: Step S1: Based on the beacon light signal transmitted by the other party terminal, calculate the time delay from the transmission of the signal to the reception of the signal at this end, and perform compensation calculation on the current position of the other party terminal based on the time delay to obtain the first position estimate of the other party terminal. Step S2: Monitor the vibration state of the local platform in real time, obtain the optical axis offset caused by the platform vibration, and generate vibration compensation to compensate for the optical axis offset; Step S3: Calculate the transmission time delay required for the signal transmitted from this end to reach the other end, and predict the position of the other end at the time of signal arrival based on the transmission time delay to obtain the second position estimate of the other end. Step S4: Calculate the composite advance aiming angle by combining the first position estimate, the vibration compensation command, and the second position estimate; Step S5: Adjust the direction of the laser emission axis according to the composite pre-aiming angle.

[0011] Preferably, step S1 includes: Step S1.1: Determine the azimuth and elevation angles of the other terminal at the time of transmission based on the received beacon light signal; Step S1.2: Extract the transmission timestamp of the other terminal from the beacon optical signal. Record the local receiving time. ; Step S1.3: Calculate the reception delay ; Step S1.4: Calculate the position of the other terminal at the time of transmission based on its azimuth and elevation angles. ; Step S1.5: Obtain the velocity vector of the other terminal. and acceleration vector ; Step S1.6: Calculate the current location of the other terminal The calculation formula is: .

[0012] Preferably, step S2 includes: Step S2.1: Collect the angular velocity of the local platform using the inertial measurement unit. and angular acceleration data; Step S2.2: Assess the collected local platform angular velocity. and angular acceleration The data is subjected to spectral analysis to identify vibration characteristics; Step S2.3: Construct a platform vibration model based on vibration characteristics, and use an adaptive Kalman filter algorithm to predict the vibration state based on the platform vibration model. Obtain the platform attitude deviation at the launch time based on the predicted vibration state. ; Step S2.4: Calculate the optical axis compensation amount .

[0013] Preferably, step S3 includes: Step S3.1: Calculate the distance between the local terminal and the other terminal based on the reception delay or ephemeris data. ; Step S3.2: Calculate the transmission delay of the transmitted signal Where c is the speed of light; Step S3.3: Obtain the orbital parameters of the other terminal and predict its time. Location ;in, The current moment; Step S3.4: Based on the time of the other party's terminal Location Calculate the distance between the local terminal and the remote terminal. ; Step S3.5: Calculate the launch advance angle ;in, This represents the tangential velocity component of the other terminal relative to the line-of-sight direction of this terminal.

[0014] Preferably, step S4 includes: Step S4.1: Set the current location of the other party's terminal Converted to receive delay compensation angle And will receive delay compensation angle Transform to the aiming coordinate system; Step S4.2: Adjust the platform vibration compensation angle Transform to the aiming coordinate system; Step S4.3: Adjust the launch advance angle Converted to launch delay compensation angle and will compensate for launch delay angle Transform to the aiming coordinate system; Step S4.4: Calculate the composite advance aiming angle: ; in, This is the reference aiming angle based on the currently received signal; Step S4.5: Perform a rationality check on the composite aiming angle to ensure that it meets the preset requirements and is within the working range of the aiming mechanism.

[0015] A composite advance aiming system for tracking a lunar-Earth laser communication link, provided by the present invention, includes: Module M1: Based on the beacon light signal transmitted by the other party terminal, calculate the time delay from the transmission of the signal to the reception of the signal at this end, and perform compensation calculation on the current position of the other party terminal based on the time delay to obtain the first position estimate of the other party terminal. Module M2: Real-time monitoring of the vibration status of the local platform, obtaining the optical axis offset caused by the platform vibration, and generating vibration compensation to compensate for the optical axis offset; Module M3: Calculates the transmission time delay required for the local transmitted signal to reach the other terminal, and predicts the location of the other terminal at the time of signal arrival based on the transmission time delay, thereby obtaining a second location estimate of the other terminal; Module M4: Combines the first position estimate, vibration compensation command, and second position estimate to calculate the composite advance aiming angle; Module M5: Adjusts the direction of the laser emission axis according to the composite pre-aiming angle.

[0016] Preferably, the module M1 includes: Module M1.1: Determines the azimuth and elevation angles of the other terminal at the time of transmission based on the received beacon light signal; Module M1.2: Extracts the transmission timestamp of the other terminal from the beacon optical signal. Record the local receiving time. ; Module M1.3: Calculates receive delay ; Module M1.4: Calculates the position of the other terminal at the time of transmission based on its azimuth and elevation angles. ; Module M1.5: Obtain the velocity vector of the other terminal. and acceleration vector ; Module M1.6: Calculates the current location of the other terminal The calculation formula is: .

[0017] Preferably, the module M2 includes: Module M2.1: Acquires the angular velocity of the local platform via the inertial measurement unit. and angular acceleration data; Module M2.2: Collects the local platform angular velocity. and angular acceleration The data is subjected to spectral analysis to identify vibration characteristics; Module M2.3: Constructs a platform vibration model based on vibration characteristics, uses an adaptive Kalman filter algorithm to predict the vibration state based on the platform vibration model, and obtains the platform attitude deviation at the launch time based on the predicted vibration state. ; Module M2.4: Calculate optical axis compensation amount .

[0018] Preferably, the module M3 includes: Module M3.1: Calculates the distance between the local terminal and the remote terminal based on the reception delay or ephemeris data. ; Module M3.2: Calculates the transmission delay of the transmitted signal Where c is the speed of light; Module M3.3: Obtains the orbital parameters of the other terminal and predicts its time. Location ;in, The current moment; Module M3.4: Based on the time of the other party's terminal Location Calculate the distance between the local terminal and the remote terminal. ; Module M3.5: Calculates the launch advance angle ;in, This represents the tangential velocity component of the other terminal relative to the line-of-sight direction of this terminal.

[0019] Preferably, the module M4 includes: Module M4.1: Sets the current location of the other party's terminal. Converted to receive delay compensation angle And will receive delay compensation angle Transform to the aiming coordinate system; Module M4.2: Adjusts the platform vibration compensation angle. Transform to the aiming coordinate system; Module M4.3: Adjusts the launch advance angle Converted to launch delay compensation angle and will compensate for launch delay angle Transform to the aiming coordinate system; Module M4.4: Calculate the composite advance aiming angle: ; in, This is the reference aiming angle based on the currently received signal; Module M4.5: Performs a rationality check on the composite aiming angle to ensure it meets the preset requirements and is within the working range of the aiming mechanism.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention comprehensively considers three factors: receiving delay compensation, platform vibration compensation, and transmitting delay compensation, achieving comprehensive advance aiming and effectively solving the pointing deviation problem caused by various delays and disturbances in long-distance laser communication between the moon and the earth. 2. The receiving delay compensation module used in this invention calculates the current position of the other party's terminal by extrapolation, thereby eliminating the position lag effect caused by the receiving signal delay and improving the accuracy of position estimation. 3. The platform vibration compensation module used in this invention actively compensates for the optical axis offset caused by the platform vibration by real-time monitoring and prediction, thereby improving aiming stability in dynamic environments. 4. The transmission delay compensation module used in this invention can accurately aim in advance by predicting the position of the other party terminal at the time of signal arrival, thus ensuring that the transmitted signal can accurately reach the other party terminal. 5. The composite aiming calculation method adopted in this invention organically combines the three types of compensation to achieve synergistic optimization, and the overall aiming accuracy is better than the simple superposition of the individual compensations.

[0021] 6. This invention supports closed-loop correction and can adaptively adjust compensation parameters based on the signal quality information fed back by the other party, exhibiting good adaptability and robustness. Attached Figure Description

[0022] 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 This is a block diagram of the overall architecture of the composite early targeting system.

[0023] Figure 2 Timing diagram for laser signal transmission and compensation calculation for lunar-Earth laser communication ground station.

[0024] Figure 3 This is a diagram of the components of a composite early aiming system.

[0025] Figure 4 This is a flowchart of the composite advance aiming method.

[0026] Figure 5 This is a block diagram of the target execution control unit. Detailed Implementation

[0027] 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.

[0028] Example 1 The purpose of this invention is to provide a composite advance aiming system and method for tracking lunar-Earth laser communication links, so as to solve the problem of insufficient aiming accuracy caused by the failure to comprehensively consider various delay and disturbance factors in the prior art.

[0029] A composite advance aiming system for tracking a lunar-Earth laser communication link according to the present invention includes: an aiming control device disposed at a lunar orbit laser terminal and a ground station; The aiming control device includes: The receiving delay compensation module is used to calculate the time delay from the receiving signal transmitted by the other party to the receiving signal of the local terminal based on the received signal transmitted by the other party, and to perform compensation calculation on the current position of the other party terminal based on the time delay to obtain the first position estimate of the other party terminal. The platform vibration compensation module is used to monitor the vibration status of the local platform in real time, obtain the optical axis offset caused by the platform vibration, and generate a vibration compensation command to compensate for the optical axis offset. The transmission delay compensation module is used to calculate the transmission time delay required for the local transmitted signal to reach the other party terminal, and predict the position of the other party terminal at the time of signal arrival based on the transmission time delay, thereby obtaining a second position estimate of the other party terminal. The composite aiming calculation module is used to combine the first position estimate, the vibration compensation command, and the second position estimate to calculate the composite advance aiming angle and output the aiming control command. The aiming actuator is used to adjust the direction of the laser emission optical axis according to the aiming control command.

[0030] Specifically, the receiving delay compensation module includes: The signal receiving unit is used to receive beacon light signals transmitted by the other party's terminal; Angle of arrival measurement unit, used to measure the angle of arrival of the beacon light signal; The timestamp extraction unit is used to extract the transmission timestamp of the other party terminal from the beacon optical signal; The delay calculation unit is used to calculate the signal transmission delay based on the local reception time and the transmission timestamp. The position extrapolation unit is used to extrapolate and calculate the current position of the other terminal based on the arrival angle, the signal transmission delay, and the motion model of the other terminal.

[0031] Specifically, the position extrapolation unit performs position extrapolation using the following formula:

[0032] in, Estimate the current location of the other terminal. This refers to the location of the other terminal at the time of transmission. Let the velocity vector of the other terminal be _____. Let be the acceleration vector of the other terminal. This is the reception delay time.

[0033] Specifically, the platform vibration compensation module includes: An inertial measurement unit is used to measure the angular velocity and angular acceleration of the local platform. The vibration analysis unit is used to perform spectral analysis on the angular velocity and angular acceleration to identify vibration characteristics; The vibration prediction unit is used to construct a vibration model based on the vibration characteristics, use an adaptive Kalman filter algorithm to predict the vibration state based on the platform vibration model, and obtain the platform attitude offset at the launch time based on the predicted vibration state. The compensation calculation unit is used to calculate the optical axis compensation amount based on the platform attitude offset.

[0034] Specifically, the vibration prediction unit employs an adaptive Kalman filter algorithm, and its state equation is:

[0035]

[0036] in, This is the state vector, containing the platform's attitude angles, angular velocity, and angular acceleration. Here is the state transition matrix. For process noise, For the observation vector, For the observation matrix, To observe noise.

[0037] Specifically, the transmission delay compensation module includes: The distance estimation unit is used to estimate the distance to the other terminal based on the received signal delay or ephemeris data. A transmission time calculation unit is used to calculate the signal transmission time based on the distance; The trajectory prediction unit is used to predict the position of the other terminal at the time of signal arrival based on the trajectory parameters of the other terminal. The aiming angle preset unit is used to calculate the firing angle required to point to the predicted position.

[0038] The aiming angle preset unit calculates the launch advance angle using the following formula:

[0039] in, For the launch advance angle, This represents the tangential velocity component of the other terminal relative to the line-of-sight direction of this terminal. Due to signal transmission delay, This represents the distance between the local terminal and the other terminal.

[0040] Specifically, the composite aiming calculation module uses the following formula to calculate the composite advance aiming angle:

[0041] in, For the composite advance aiming angle vector, The reference aiming angle is based on the currently received signal. To compensate for the reception delay angle, For the platform vibration compensation angle, The angle is for launch delay compensation.

[0042] Specifically, the aiming actuator includes: A coarse aiming mechanism is used to achieve pointing adjustments over a wide range of angles; A precision aiming mechanism is used to achieve high-precision micro-angle adjustments.

[0043] Preferably, the system further includes a communication protocol module, which is used to transmit timestamp information, position information and velocity information between the lunar orbit laser terminal and the ground station to support coordinated advance aiming between the two parties.

[0044] A composite advance aiming method for tracking a lunar-Earth laser communication link according to the present invention includes: Receive delay compensation steps: Receive the beacon light signal transmitted by the other party terminal, measure the signal arrival angle, extract the signal transmission timestamp, calculate the signal transmission delay, and extrapolate the current position of the other party terminal based on the transmission delay and the motion model of the other party terminal to obtain the first position estimate; Platform vibration compensation steps: Real-time monitoring of the vibration state of the local platform, acquisition of angular velocity and angular acceleration data, vibration analysis and prediction, calculation of platform attitude offset at launch time, and generation of corresponding optical axis compensation amount; Transmission delay compensation steps: Calculate the signal transmission time based on the distance between the local terminal and the other terminal, predict the position of the other terminal at the time of signal arrival based on the orbital parameters of the other terminal, obtain the second position estimate, and calculate the corresponding transmission advance angle; Composite aiming calculation steps: Combine the first position estimate, the optical axis compensation amount, and the second position estimate to calculate the composite advance aiming angle; Aiming execution steps: Control the aiming execution mechanism according to the composite advance aiming angle to adjust the direction of the laser emission optical axis.

[0045] Specifically, the reception delay compensation step includes: Step S1.1: Determine the azimuth and elevation angles of the other terminal at the time of transmission based on the received beacon light signal; Step S1.2: Extract the transmission timestamp of the other terminal from the signal. Record the local reception time. ; Step S1.3: Calculate the reception delay ; Step S1.4: Calculate the position of the other terminal at the time of transmission based on its azimuth and elevation angles. ; Step S1.5: Obtain the velocity vector of the other terminal. and acceleration vector ; Step S1.6: Calculate the current location of the other terminal : .

[0046] Specifically, the platform vibration compensation steps include: Step S2.1: Collect the platform's angular velocity using the inertial measurement unit. and angular acceleration data; Step S2.2: Perform spectral analysis on the collected data to identify the main vibration frequency components; Step S2.3: Establish a platform vibration model based on the identified main vibration frequency components, and estimate the vibration state using an adaptive Kalman filter based on the platform vibration model; Step S2.4: Predict the platform attitude deviation at the launch moment based on the estimated vibration state. ; Step S2.5: Calculate the optical axis compensation amount .

[0047] Specifically, the platform vibration compensation steps include: Step S3.1: Calculate the distance between the local terminal and the other terminal based on the reception delay or ephemeris data. 1; Step S3.2: Calculate the transmission delay of the transmitted signal , where c is the speed of light; Step S3.3: Obtain the orbital parameters of the other terminal and predict its time. Location ; Step S3.4: Based on the time of the other party's terminal Location Calculate the distance between the local terminal and the remote terminal. ; Step S3.5: Calculate the launch advance angle .

[0048] Specifically, the transmission delay compensation step includes: Step S4.1: Set the current location of the other party's terminal Converted to receive delay compensation angle And will receive delay compensation angle Transform to the aiming coordinate system; Step S4.2: Adjust the platform vibration compensation angle Transform to the aiming coordinate system; Step S4.3: Adjust the launch advance angle Converted to launch delay compensation angle and will compensate for launch delay angle Transform to the aiming coordinate system; Step S4.4: Calculate the composite advance aiming angle: ; Step S4.5: Perform a rationality check on the composite aiming angle to ensure it is within the working range of the aiming mechanism.

[0049] Specifically, the method further includes a closed-loop correction step: Step S6: Receive signal quality information fed back by the other party's terminal; Step S7: Evaluate aiming accuracy based on the signal quality information; Step S8: Adaptively adjust the parameters of the compensation model to optimize subsequent aiming accuracy.

[0050] Specifically, the receiving delay compensation step, platform vibration compensation step, transmitting delay compensation step, composite aiming calculation step, and aiming execution step are executed cyclically according to a set control cycle. The control cycle is determined based on link requirements and platform stability, and ranges from 0.1 milliseconds to 10 milliseconds.

[0051] A lunar-Earth laser communication system provided by the present invention includes: A lunar orbital laser terminal, installed on a lunar orbital spacecraft; Ground stations are located on the Earth's surface; Both the lunar orbit laser terminal and the ground station are equipped with the composite advance aiming system described above.

[0052] Example 2 Example 2 is a preferred example of Example 1. like Figure 1 , Figure 2 , Figure 3 This embodiment provides a composite advance aiming system for tracking a lunar-Earth laser communication link, applied to a lunar-Earth laser communication system. This lunar-Earth laser communication system includes a laser terminal located in lunar orbit and a ground station located on the Earth's surface, such as... Figure 2 As shown, the two communicate bidirectionally via a laser link.

[0053] Both the lunar orbit laser terminal and the ground station are equipped with the composite advance aiming system described in this embodiment. The following detailed description takes the lunar orbit laser terminal as an example, and the configuration of the ground station is similar.

[0054] like Figure 3 As shown, the composite advance aiming system in the lunar-Earth laser communication link tracking includes: The receiver delay compensation module includes: a signal receiving unit, an angle of arrival measurement unit, a timestamp extraction unit, a delay calculation unit, and a position extrapolation unit.

[0055] The signal receiving unit is used to receive beacon optical signals transmitted by the ground station. In addition to carrying communication data, the beacon optical signal also contains transmission timestamp information.

[0056] The angle of arrival measurement unit uses a four-quadrant detector or a CCD camera to measure the angle of arrival of the beacon light signal with an accuracy down to the microradian level.

[0057] The timestamp extraction unit demodulates and extracts the transmission timestamp from the received beacon optical signal. The local terminal maintains a high-precision clock synchronized with the remote terminal to ensure the validity of the timestamp.

[0058] The delay calculation unit calculates the signal transmission delay based on the local reception time and the other party's transmission timestamp. For a distance of approximately 380,000 kilometers between the Earth and the Moon, the signal transmission delay is approximately 1.28 seconds.

[0059] The position extrapolation unit calculates the current position of the other terminal based on the arrival angle, signal transmission delay, and the motion model of the other terminal. The extrapolation formula is:

[0060] Among them, the velocity and acceleration information of the other terminal can be obtained in the following ways: (1) demodulation from the received signal, the other terminal encodes its own motion parameters in the signal and transmits them; (2) calculation based on the orbital parameters of the other terminal; (3) fitting through position observations at multiple times.

[0061] The platform vibration compensation module includes an inertial measurement unit, a vibration analysis unit, a vibration prediction unit, and a compensation calculation unit.

[0062] An inertial measurement unit (IMU), mounted on the laser terminal platform, measures the platform's three-axis angular velocity and angular acceleration in real time. Employing high-precision fiber optic gyroscopes or laser gyroscopes, the measurement accuracy can reach 0.001° / s.

[0063] The vibration analysis unit performs spectral analysis on the measured angular velocity and angular acceleration to identify the platform's main vibration modes and characteristic frequencies. Typical vibration sources for lunar orbiting spacecraft include: control torque of the attitude control system, flexible vibration of the solar panels, thermal deformation, etc., with vibration frequencies typically ranging from 0.01Hz to 100Hz.

[0064] The vibration prediction unit establishes a platform vibration model and uses an adaptive Kalman filter algorithm for state estimation and prediction. The state vector contains nine elements: three-axis attitude angles, angular velocity, and angular acceleration. By predicting the vibration state, the platform attitude deviation at launch time can be obtained.

[0065] The compensation calculation unit calculates the required optical axis compensation amount based on the predicted platform attitude offset. The compensation direction is opposite to the predicted offset direction, and the magnitude is equal to counteract the effects of vibration.

[0066] The launch delay compensation module includes a distance estimation unit, a transmission time calculation unit, an orbit prediction unit, and an aiming angle preset unit.

[0067] The distance estimation unit estimates the distance to the other terminal based on the round-trip delay of the received signal or ephemeris data. For Earth-Moon communication, the distance range is approximately 356,000 to 406,000 kilometers.

[0068] The transmission time calculation unit calculates the signal transmission time based on the distance. Where c is the speed of light (approximately 3 × 10⁻⁶) 8 m / s).

[0069] The orbit prediction unit predicts the location of the receiving terminal at the time of signal arrival based on its orbital parameters. For ground stations, the influence of Earth's rotation needs to be considered; for lunar orbit terminals, the influence of lunar orbital motion needs to be considered.

[0070] The aiming angle preset unit calculates the launch angle required to point at the predicted position. The formula for calculating the launch advance angle is:

[0071] The composite aiming calculation module integrates the outputs of the three compensation modules to calculate the composite advance aiming angle. The composite formula is: ; in, The three compensation angles are derived from the calculation results of three compensation modules, respectively, to establish a reference aiming angle based on the currently received signal. The composite aiming calculation module also performs a reasonableness check on the calculation results to ensure that they are within the working range of the aiming mechanism.

[0072] The aiming mechanism includes coarse aiming mechanism and fine aiming mechanism.

[0073] The coarse aiming mechanism adopts a two-dimensional turntable to achieve a wide range of pointing adjustments, with an adjustment range of ±30° and a resolution of approximately 0.01°.

[0074] The precision aiming mechanism uses a two-dimensional fast-swinging mirror driven by piezoelectric ceramics to achieve high-frequency, high-precision micro-angle adjustment, with an adjustment range of approximately ±1° and a resolution down to the microradian level.

[0075] This embodiment can also be extended with a communication protocol module to transmit collaborative information between the lunar orbit laser terminal and the ground station, including parameters such as timestamps, positions, speeds, and attitudes, to support collaborative pre-aiming between the two parties.

[0076] like Figure 4 , Figure 5 As shown, this embodiment provides a composite advance aiming method for tracking a lunar-Earth laser communication link, including the following steps: Step S1: Receive delay compensation; Step S1.1: Receive the beacon light signal transmitted by the other party's terminal through the signal receiving unit; Step S1.2: Measure the angle of arrival (azimuth α and elevation β) of the beacon light signal using the angle of arrival measurement unit. Step S1.3: Extract the transmission timestamp of the other terminal from the signal using the timestamp extraction unit. ; Step S1.4: Record the local reception time. Calculate the receiving delay ; Step S1.5: Calculate the position of the other terminal at the time of transmission based on the angle of arrival. ; Step S1.6: Obtain the velocity vector of the other terminal. and acceleration vector ; S1.7: Calculate the estimated current location of the other terminal using an extrapolation formula. ; S1.8: Will Converted to receive delay compensation angle .

[0077] Step S2: Platform vibration compensation; Step S2.1: Collect the platform's angular velocity using the inertial measurement unit. and angular acceleration data; Step S2.2: Perform spectral analysis on the collected data to identify the main vibration frequency components; Step S2.3: Update the state estimate of the platform vibration model; Step S2.4: Predict the platform attitude deviation at the launch time based on the vibration model (considering system processing delay and actuator response time). ; Step S2.5: Calculate the optical axis compensation amount .

[0078] Step S3: Launch delay compensation; Step S3.1: Calculate the distance between the local terminal and the other terminal based on the reception delay or ephemeris data. ; Step S3.2: Calculate the transmission delay of the transmitted signal ; Step S3.3: Calculate the lateral velocity component of the other terminal relative to the line-of-sight direction of this terminal. ; Step S3.4: Predict the location of the other terminal at the time of signal arrival. ; Step S3.5: Calculate the launch advance angle Converted to launch delay compensation angle .

[0079] Step S4: Composite aiming calculation; Step S4.1: Obtain the reference aiming angle based on the currently received signal. ; Step S4.2: [The text appears to be incomplete and contains several grammatical errors. A more accurate translation would require , , Transform to the aiming coordinate system; Step S4.3: Calculate the composite advance aiming angle: ; Step S4.4: For Amplitude limiting is applied to ensure that the target remains within the working range of the aiming mechanism; Step S4.5: Generate aiming control commands.

[0080] Step S5: Target and execute; Step S5.1: Decompose the aiming control command into coarse aiming command and fine aiming command; Step S5.2: The coarse aiming mechanism performs a large-angle adjustment; Step S5.3: The precision aiming mechanism performs micro-angle high-frequency vibration compensation adjustment; Step S5.4: After confirming that the aiming is in place, emit a laser signal.

[0081] Step S6: Closed-loop calibration; Step S6.1: Receive signal quality information (such as signal strength, bit error rate, etc.) fed back by the other party's terminal. Step S6.2: Evaluate aiming accuracy based on signal quality information; Step S6.3: If the aiming accuracy does not meet the requirements, adaptively adjust the compensation model parameters; Step S6.4: Apply the adjusted parameters to subsequent control cycles.

[0082] Steps S1 to S5 described above are executed cyclically according to a set control cycle. Depending on link requirements and platform stability, the control cycle can be set from 0.1 milliseconds to 10 milliseconds. A shorter control cycle can improve the responsiveness to dynamic changes but increases the computational burden; a longer control cycle has a lower computational burden but poorer adaptability to rapid changes. In this embodiment, the control cycle is preferably 1 millisecond.

[0083] Example 3 Example 3 is a preferred example of Example 1. This embodiment provides a specific numerical calculation example to illustrate the implementation effect of the composite advance aiming method of the present invention.

[0084] The scenario parameters are assumed to be as follows: (1) Earth-Moon distance: R = 380,000 km (2) Speed ​​of light: c = 299,792.458 km / s (3) Signal transmission delay: τ = R / c ≈ 1.267 s (4) Lunar orbital terminal velocity: V_moon ≈ 1.6 km / s (5) Linear velocity of the ground station due to the Earth's rotation: V_earth ≈ 0.46 km / s (equator) (6) Platform vibration amplitude: approximately 10 microradians (typical value) The receiving delay compensation is calculated as follows: (1) When the beacon light from the ground station is received, the ground station has already moved: km (2) Corresponding angular deviation:

[0085] The launch delay compensation is calculated as follows: (1) When the transmitted signal reaches the ground station, the ground station will move again: km (2) Corresponding launch advance angle:

[0086] The platform vibration compensation is calculated as follows: (1) Assume the current predicted platform attitude offset is:

[0087] (2) Composite aiming angle:

[0088] The calculations above show that platform vibration compensation dominates the total compensation, but receive delay compensation and transmit delay compensation are not negligible. For micro-radian laser communication systems, the absence of any one of these compensations can lead to pointing deviations exceeding acceptable limits.

[0089] This invention takes into account three compensation factors, which can achieve aiming accuracy at the sub-microradian level and meet the link requirements of lunar-Earth laser communication.

[0090] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0091] 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 composite advance aiming method for tracking in a lunar-Earth laser communication link, characterized in that, include: Step S1: Based on the beacon light signal transmitted by the other party terminal, calculate the time delay from the transmission of the signal to the reception of the signal at this end, and perform compensation calculation on the current position of the other party terminal based on the time delay to obtain the first position estimate of the other party terminal. Step S2: Monitor the vibration state of the local platform in real time, obtain the optical axis offset caused by the platform vibration, and generate vibration compensation to compensate for the optical axis offset; Step S3: Calculate the transmission time delay required for the signal transmitted from this end to reach the other end, and predict the position of the other end at the time of signal arrival based on the transmission time delay to obtain the second position estimate of the other end. Step S4: Calculate the composite advance aiming angle by combining the first position estimate, the vibration compensation command, and the second position estimate; Step S5: Adjust the direction of the laser emission axis according to the composite pre-aiming angle.

2. The composite advance aiming method in lunar-Earth laser communication link tracking according to claim 1, characterized in that, Step S1 includes: Step S1.1: Determine the azimuth and elevation angles of the other terminal at the time of transmission based on the received beacon light signal; Step S1.2: Extract the transmission timestamp of the other terminal from the beacon optical signal. Record the local receiving time. ; Step S1.3: Calculate the reception delay ; Step S1.4: Calculate the position of the other terminal at the time of transmission based on its azimuth and elevation angles. ; Step S1.5: Obtain the velocity vector of the other terminal. and acceleration vector ; Step S1.6: Calculate the current location of the other terminal The calculation formula is: 。 3. The composite advance aiming method in lunar-Earth laser communication link tracking according to claim 1, characterized in that, Step S2 includes: Step S2.1: Collect the angular velocity of the local platform using the inertial measurement unit. and angular acceleration data; Step S2.2: Assess the collected local platform angular velocity. and angular acceleration The data is subjected to spectral analysis to identify vibration characteristics; Step S2.3: Construct a platform vibration model based on vibration characteristics, and use an adaptive Kalman filter algorithm to predict the vibration state based on the platform vibration model. Obtain the platform attitude deviation at the launch time based on the predicted vibration state. ; Step S2.4: Calculate the optical axis compensation amount .

4. The composite advance aiming method in lunar-Earth laser communication link tracking according to claim 1, characterized in that, Step S3 includes: Step S3.1: Calculate the distance between the local terminal and the other terminal based on the reception delay or ephemeris data. ; Step S3.2: Calculate the transmission delay of the transmitted signal Where c is the speed of light; Step S3.3: Obtain the orbital parameters of the other terminal and predict its time. Location ;in, The current moment; Step S3.4: Based on the time of the other party's terminal Location Calculate the distance between the local terminal and the remote terminal. ; Step S3.5: Calculate the launch advance angle ;in, This represents the tangential velocity component of the other terminal relative to the line-of-sight direction of this terminal.

5. The composite advance aiming method in lunar-Earth laser communication link tracking according to claim 1, characterized in that, Step S4 includes: Step S4.1: Set the current location of the other party's terminal Converted to receive delay compensation angle And will receive delay compensation angle Transform to the aiming coordinate system; Step S4.2: Adjust the platform vibration compensation angle Transform to the aiming coordinate system; Step S4.3: Adjust the launch advance angle Converted to launch delay compensation angle and the launch delay compensation angle Transform to the aiming coordinate system; Step S4.4: Calculate the composite advance aiming angle: ； in, This is the reference aiming angle based on the currently received signal; Step S4.5: Perform a rationality check on the composite aiming angle to ensure that it meets the preset requirements and is within the working range of the aiming mechanism.

6. A composite advance aiming system for tracking in a lunar-Earth laser communication link, characterized in that, include: Module M1: Based on the beacon light signal transmitted by the other party terminal, calculate the time delay from the transmission of the signal to the reception of the signal at this end, and perform compensation calculation on the current position of the other party terminal based on the time delay to obtain the first position estimate of the other party terminal. Module M2: Real-time monitoring of the vibration status of the local platform, obtaining the optical axis offset caused by the platform vibration, and generating vibration compensation to compensate for the optical axis offset; Module M3: Calculates the transmission time delay required for the local transmitted signal to reach the other terminal, and predicts the location of the other terminal at the time of signal arrival based on the transmission time delay, thereby obtaining a second location estimate of the other terminal; Module M4: Combines the first position estimate, vibration compensation command, and second position estimate to calculate the composite advance aiming angle; Module M5: Adjusts the direction of the laser emission axis according to the composite pre-aiming angle.

7. The composite advance aiming system for tracking the lunar-Earth laser communication link according to claim 6, characterized in that, The module M1 includes: Module M1.1: Determines the azimuth and elevation angles of the other terminal at the time of transmission based on the received beacon light signal; Module M1.2: Extracts the transmission timestamp of the other terminal from the beacon optical signal. Record the local receiving time. ; Module M1.3: Calculates receive delay ; Module M1.4: Calculates the position of the other terminal at the time of transmission based on its azimuth and elevation angles. ; Module M1.5: Obtain the velocity vector of the other terminal. and acceleration vector ; Module M1.6: Calculates the current location of the other terminal The calculation formula is: 。 8. The composite advance aiming system for tracking a lunar-Earth laser communication link according to claim 6, characterized in that, The module M2 includes: Module M2.1: Acquires the angular velocity of the local platform via the inertial measurement unit. and angular acceleration data; Module M2.2: Collects the local platform angular velocity. and angular acceleration The data is subjected to spectral analysis to identify vibration characteristics; Module M2.3: Constructs a platform vibration model based on vibration characteristics, uses an adaptive Kalman filter algorithm to predict the vibration state based on the platform vibration model, and obtains the platform attitude deviation at the launch time based on the predicted vibration state. ; Module M2.4: Calculate optical axis compensation amount .

9. The composite advance aiming system for tracking a lunar-Earth laser communication link according to claim 6, characterized in that, The module M3 includes: Module M3.1: Calculates the distance between the local terminal and the remote terminal based on the reception delay or ephemeris data. ; Module M3.2: Calculates the transmission delay of the transmitted signal Where c is the speed of light; Module M3.3: Obtains the orbital parameters of the other terminal and predicts its time. Location ;in, The current moment; Module M3.4: Based on the time of the other party's terminal Location Calculate the distance between the local terminal and the remote terminal. ; Module M3.5: Calculates the launch advance angle ;in, This represents the tangential velocity component of the other terminal relative to the line-of-sight direction of this terminal.

10. The composite advance aiming system for tracking a lunar-Earth laser communication link according to claim 6, characterized in that, The module M4 includes: Module M4.1: Sets the current location of the other party's terminal. Converted to receive delay compensation angle And will receive delay compensation angle Transform to the aiming coordinate system; Module M4.2: Adjusts the platform vibration compensation angle. Transform to the aiming coordinate system; Module M4.3: Adjusts the launch advance angle Converted to launch delay compensation angle and the launch delay compensation angle Transform to the aiming coordinate system; Module M4.4: Calculate the composite advance aiming angle: ； in, This is the reference aiming angle based on the currently received signal; Module M4.5: Performs a rationality check on the composite aiming angle to ensure it meets the preset requirements and is within the working range of the aiming mechanism.

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