A laser communication terminal initial pointing determination method and related equipment

Abstract

The present invention relates to the field of laser communication technology, and specifically to a method for determining the initial pointing of a laser communication terminal and related equipment. The method is for a laser communication terminal on a tethered balloon platform, obtains the baseline vectors of two antennas through a dual-station GNSS receiver, and calculates the heading angle using differential positioning; at the same time, with the help of the platform's inertial measurement unit, attitude information is measured in real time, and the initial pointing vector is calculated by combining the heading angle and attitude information, ultimately obtaining an initial pointing angle including an azimuth and pitch angle. The present invention has the advantages of high precision, rapid deployment, and strong anti-interference capability, can significantly shorten the time it takes to establish a laser communication link, and is suitable for emergency communications, military communications, scientific observation and other fields.

Description

Technical Field

[0001] The present invention relates to the technical field of laser communication, and in particular to a method for determining the initial pointing of a laser communication terminal and related equipment. Background Art

[0002] With the rapid development of laser communication technology, it has demonstrated tremendous application potential and value in a wide range of fields, including emergency communications, military communications, and scientific observation. Laser communication, with its significant advantages such as high transmission rates, strong anti-interference capabilities, and excellent concealment, has become an ideal choice for ultra-long-distance communications.

[0003] Tethered balloon platforms, with their unique characteristics of long-term airborne presence and wide coverage, are ideal carriers for laser communications. However, when used in high-altitude laser communications, tethered balloon platforms face numerous challenges that need to be addressed, particularly in initial pointing and rapid link establishment.

[0004] The initial pointing of laser communication refers to the process of accurately aligning the laser beam from the transmitter to the receiver before the laser communication link is established. However, the divergence angle of the laser communication beam is extremely small, usually at the micro-radian level, which means that the initial pointing error will have a significant impact on the capture efficiency. Traditional initial pointing methods mainly rely on star observation or beacon light systems. Although star observation can provide higher pointing accuracy to a certain extent, this method is severely restricted by weather conditions. Once the weather conditions are bad, such as cloud cover, the observation work will not be able to be carried out normally, which will affect the accuracy and timeliness of the initial pointing. Although the beacon light system can also achieve higher pointing accuracy, it not only increases the complexity of the system, but also increases the power consumption of the system, which is not conducive to the overall optimization and long-term stable operation of the system.

[0005] Furthermore, tethered balloon platforms are highly susceptible to external factors such as wind and temperature fluctuations at high altitudes, leading to unstable platform attitudes. This instability further complicates initial pointing, making traditional initial pointing methods even more challenging to implement in practice.

[0006] When it comes to attitude measurement, existing methods, such as a single GNSS (Global Navigation Satellite System) or IMU (Inertial Measurement Unit), suffer from significant inaccuracies and stability in dynamic environments. Laser communications require extremely high pointing accuracy, which a single GNSS or IMU struggles to meet. This results in significant initial pointing errors, hindering the proper establishment of the laser communication link.

[0007] Furthermore, traditional initial pointing methods often require complex calibration processes, such as those involving star observation or beacon optical systems. These complex calibration processes result in long deployment times, making it difficult to meet the demands of timely communication in emergency communications and rapid response scenarios, thus limiting the application effectiveness and development prospects of laser communications on tethered balloon platforms. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method for determining the initial pointing of a laser communication terminal and related equipment in response to the above-mentioned deficiencies in the prior art, so as to solve the technical problem that the initial pointing determination accuracy of the laser communication terminal is low due to the unstable posture of the tethered balloon platform.

[0009] The purpose of the present invention is achieved by the following technical solutions:

[0010] In a first aspect, the present invention provides a method for determining an initial pointing direction of a laser communication terminal, comprising:

[0011] A dual-station GNSS receiver deployed on a laser communication terminal is used to obtain a baseline vector between two antennas, and a heading angle of the laser communication terminal is calculated based on the baseline vector using a differential positioning method; the laser communication terminal is mounted on a tethered balloon platform;

[0012] The inertial measurement unit provided on the tethered balloon platform measures the attitude information of the tethered balloon platform in real time, and obtains the attitude information of the laser communication terminal according to the attitude information;

[0013] An initial pointing vector is calculated based on the heading angle and attitude information of the laser communication terminal, and an initial pointing angle of the laser communication terminal is obtained based on the initial pointing vector. The initial pointing angle includes an azimuth angle and a pitch angle.

[0014] As a further improvement of the present invention, the heading angle of the laser communication terminal is calculated using a differential positioning method based on the baseline vector, specifically including:

[0015] The dual-station GNSS receivers synchronously obtain the WGS84 coordinates of the two antennas; convert the WGS84 coordinates of the two antennas to the station-centered coordinate system, and calculate the baseline vector heading angles of the two antennas in the station-centered coordinate system;

[0016] Introduce the carrier installation bias to correct the baseline vector heading angle:

[0017] The Kalman filter is used to fuse multiple sets of differential observations to dynamically compensate the corrected baseline heading angle and obtain the heading angle of the laser communication terminal.

[0018] As a further improvement of the present invention, the attitude information of the tethered balloon platform is measured in real time by an inertial measurement unit provided on the tethered balloon platform, specifically including:

[0019] Acquire angular velocity and acceleration data in real time based on the inertial measurement unit;

[0020] According to the angular velocity and acceleration data of the tethered balloon platform, the attitude information of the tethered balloon platform is obtained in combination with a Kalman filter algorithm, wherein the attitude information includes a pitch angle, a roll angle, and a yaw angle;

[0021] The attitude information of the laser communication terminal is determined based on the attitude information of the tethered balloon platform and the installation matrix of the tethered balloon platform and the laser communication terminal. The installation matrix is ​​the relative installation position of the tethered balloon platform and the laser communication terminal.

[0022] As a further improvement of the present invention, the calculation formula of the installation matrix is:

[0023]

[0024] Where, To install the matrix, is the azimuth, which represents the rotation angle of the laser communication terminal around the Z axis of the tethered balloon platform coordinate system; is the pitch angle, which represents the rotation angle of the laser communication terminal around the Y axis of the tethered balloon platform coordinate system; is the roll angle, which represents the rotation angle of the laser communication terminal around the X-axis of the tethered balloon platform coordinate system; It is the comprehensive projection of the laser communication terminal on the horizontal and vertical planes; is the projection of the laser communication terminal on the horizontal and vertical planes, It is the comprehensive projection of the laser communication terminal in the vertical direction. is the projection of the laser communication terminal on the horizontal plane, is the projection of the laser communication terminal on the horizontal and vertical planes, It is the comprehensive projection of the laser communication terminal in the vertical direction. is the projection of the laser communication terminal in the vertical direction, It is the comprehensive projection of the laser communication terminal on the horizontal and vertical planes. It is the comprehensive projection of the laser communication terminal in the vertical direction. is the unit vector of the laser communication terminal in the X-axis direction of the tethered balloon platform coordinate system, is the unit vector of the laser communication terminal in the Y-axis direction of the tethered balloon platform coordinate system, is the unit vector of the laser communication terminal in the Z-axis direction of the tethered balloon platform coordinate system; the X-axis in the tethered balloon platform coordinate system is defined as pointing to the heading direction of the tethered balloon platform; the Y-axis is defined as pointing to the right side of the tethered balloon platform; and the Z-axis is defined as perpendicular to the tethered balloon platform plane and pointing downward.

[0025] As a further improvement of the present invention, the calculation formula of the attitude information of the laser communication terminal is:

[0026]

[0027] Where, is the attitude information of the tethered balloon platform, To install the matrix, It is the attitude information of the laser communication terminal.

[0028] As a further improvement of the present invention, the calculation of the initial pointing vector based on the heading angle and attitude information of the laser communication terminal specifically includes:

[0029] Obtain the GNSS information of the own party and the other party from the dual-station GNSS receiver;

[0030] Calculate the relative distance and azimuth between the two tethered balloon platforms based on the GNSS information of the own party and the GNSS information of the other party, and obtain the relative position vector based on the relative distance and azimuth between the two tethered balloon platforms;

[0031] Converting the relative position vector to a laser communication terminal coordinate system with the laser communication terminal as the origin to obtain an initial pointing vector of the laser communication terminal;

[0032] The X-axis in the laser communication terminal coordinate system is defined as pointing to the emission direction of the laser communication terminal; the Y-axis is defined as pointing to the right side of the laser communication terminal; and the Z-axis is defined as perpendicular to the plane of the laser communication terminal and pointing downward.

[0033] As a further improvement of the present invention, the initial pointing angle of the laser communication terminal is obtained according to the initial pointing vector, and the calculation formula of the initial pointing angle is:

[0034]

[0035]

[0036] Where, is the azimuth, is the x-axis component of the initial pointing vector, is the y-axis component of the initial pointing vector, is the z-axis component of the initial pointing vector, is the pitch angle, is the inverse tangent function.

[0037] As a further improvement of the present invention, after obtaining the initial pointing angle of the laser communication terminal, the method further includes performing error correction on the initial pointing angle, specifically including:

[0038] The calculated initial pointing angle is input as a control instruction to a turntable control system on the tethered balloon platform to control the turntable in the turntable control system to rotate to a target position;

[0039] Monitor the target tethered balloon platform position in real time, compare the monitored target tethered balloon platform position with the initial pointing angle, and calculate the error between the current initial pointing angle and the target position;

[0040] An error correction algorithm is used to correct the initial pointing angle. When the error reaches a set threshold, the corrected instruction angle is used as a control instruction to control the turntable to rotate to the target tethered balloon platform position.

[0041] In a second aspect, the present invention provides a laser communication terminal initial pointing determination system, which is used to implement the above-mentioned laser communication terminal initial pointing determination method, including:

[0042] A dual-station GNSS receiver module is deployed on the laser communication terminal; the dual-station GNSS receiver module is used to obtain a baseline vector between two antennas and calculate the heading angle of the laser communication terminal using a differential positioning method based on the baseline vector; the laser communication terminal is mounted on the tethered balloon platform;

[0043] An inertial measurement unit is provided on the tethered balloon platform; the inertial measurement unit measures attitude information of the tethered balloon platform in real time, and obtains attitude information of the laser communication terminal based on the attitude information;

[0044] The initial pointing angle determination module calculates an initial pointing vector based on the heading angle and attitude information of the laser communication terminal, and obtains the initial pointing angle of the laser communication terminal based on the initial pointing vector. The initial pointing angle includes an azimuth angle and a pitch angle.

[0045] In a third aspect, the present invention provides a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions that, when executed by a computing device, enable the computing device to execute the above-mentioned method for determining the initial pointing of a laser communication terminal.

[0046] In a fourth aspect, the present invention provides a computing device, comprising:

[0047] One or more processors, a memory and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include methods for executing the above-mentioned laser communication terminal initial pointing determination method.

[0048] The beneficial effects of the present invention are as follows: the method for determining the initial pointing of a laser communication terminal provided by the present invention calculates the heading angle through a baseline vector using a dual-station GNSS receiver, and combines differential positioning technology to eliminate common errors, so that the positioning accuracy reaches the centimeter level, thereby providing a high-precision benchmark for the heading angle calculation. At the same time, this embodiment takes into account the influence of the tethered balloon platform on the attitude of the laser communication terminal, measures the attitude of the tethered balloon platform through an inertial measurement unit, and then compensates for the attitude deviation of the laser communication terminal caused by the shaking or deformation of the tethered balloon platform, thereby further improving the calculation accuracy of the pointing angle. The present invention integrates GNSS data information and inertial measurement unit data information, and can provide stable reference data under complex meteorological conditions, ensuring the high precision and stability of the system in a dynamic environment. At the same time, the calculated initial pointing accuracy can reach the sub-milliradian level, thereby significantly improving the efficiency of establishing the laser communication link. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 1 is a flow chart of a method for determining an initial pointing direction of a laser communication terminal according to an embodiment of the present invention;

[0051] Figure 2 This is a schematic diagram of the installation relationship between the tethered balloon and the laser terminal according to an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the relative position relationship between the own terminal and the other terminal in an embodiment of the present invention;

[0053] Figure 4 is a schematic structural diagram of an electronic device according to an embodiment of the present invention;

[0054] In the figure, 1. tethered balloon platform; 2. laser communication terminal; 21. dual-station GNSS receiver; 22. first receiving antenna; 23. second receiving antenna; 60. computer equipment; 61. processor; 62. memory; 63. computer program. DETAILED DESCRIPTION

[0055] In order to make the purpose and technical solution of the present invention clearer and easier to understand, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0056] The technical solutions of the present invention will be described clearly and completely below with reference to the accompanying drawings and specific embodiments. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0057] Example 1

[0058] like Figure 1 As shown, this embodiment provides a method for determining the initial pointing of a laser communication terminal. By combining dual-station GNSS and an inertial measurement unit, this method achieves rapid deployment and high-precision initial pointing, significantly shortening the time it takes to establish a laser communication link. The following is a specific implementation method.

[0059] First, a dual-station GNSS receiver 21 deployed on the laser communication terminal 2 acquires the baseline vector between the two antennas. Based on this baseline vector, differential positioning is used to calculate the heading angle of the laser communication terminal 2. The laser communication terminal 2 is mounted on a tethered balloon platform 1. In this embodiment, the tethered balloon platform 1 includes a tethered balloon and a platform for carrying the laser communication terminal 2.

[0060] The laser communication terminal 2 in this embodiment is equipped with a dual-station GNSS receiver 21, which measures the baseline vector between the first receiving antenna 22 and the second receiving antenna 23. In this embodiment, a certain installation distance is ensured between the two GNSS receiving antennas and the distance is known, and the GNSS antenna maintains a fixed relationship with the axis of the laser communication terminal 2. The heading angle of the laser communication terminal 2 is calculated based on the baseline vector and differential positioning technology. The differential positioning technology of the dual-station GNSS can significantly improve the measurement accuracy of the heading angle, which can usually reach within 0.1°. Both GNSS receivers are deployed at two locations of the terminal, and the connection direction of the two GNSS receivers is the direction of the terminal heading angle. The installation position spacing is greater than 1m.

[0061] The specific steps of obtaining the heading angle of the laser communication terminal 2 include:

[0062] The dual-station GNSS receiver 21 synchronously obtains the WGS84 coordinates (World Geodetic System 1984) of the two antennas;

[0063] Convert the WGS84 coordinates of the two antennas to the station center coordinate system, and calculate the baseline vector heading angles of the two antennas in the station center coordinate system;

[0064] Introduce the carrier installation bias to correct the baseline vector heading angle:

[0065] The Kalman filter is used to fuse multiple sets of differential observations to dynamically compensate the corrected baseline heading angle to obtain the heading angle of the laser communication terminal 2.

[0066] For example, Figure 2 As shown, the dual-station GNSS receiver 21 synchronously obtains the WGS84 coordinates of antenna A and antenna B: wherein, the coordinates of antenna A point are: , coordinates of antenna point B: ( ).

[0067] The WGS84 coordinates of the two antennas are converted to the station center coordinate system. The specific conversion formula is:

[0068]

[0069]

[0070]

[0071] Where, is the radius of curvature of the y-axis, e is the eccentricity of the earth, is the coordinate difference of the station center coordinate system in the x direction caused by the longitude difference, is the latitude of antenna A, is the longitude of antenna A, is the ellipsoidal elevation of antenna A, W is the latitude of antenna B, is the longitude of antenna B, is the ellipsoidal elevation of antenna B, is the coordinate difference in the y direction of the station center coordinate system caused by the latitude difference, is the coordinate difference in the z direction of the station center coordinate system corresponding to the height difference. To convert the latitude of antenna A into the x-direction component in the station center coordinate system, To convert the latitude of antenna A into the y-direction component in the station center coordinate system.

[0072] Furthermore, the calculation expression corresponding to the baseline vector heading angle is:

[0073]

[0074] Where, is the heading angle of the baseline vector. hour, .when hour, .

[0075] After the carrier installation bias correction is introduced, the calculation expression of the baseline vector heading angle is:

[0076]

[0077] Where, is the heading angle of the baseline vector after correction, is the baseline vector The theoretical installation deviation angle from the longitudinal axis of the carrier.

[0078] The Kalman filter is used to fuse multiple sets of differential observations and iteratively update them using the following formula:

[0079]

[0080] Where, is the estimated state value at the kth moment, is the estimated state value at the k-1th moment, is the observed value at the kth moment, is the observation matrix, is the Kalman gain at the kth moment.

[0081] The dual-station GNSS receiver 21 refers to a collaborative working system composed of two GNSS (Global Navigation Satellite System, such as GPS (Global Positioning System), Beidou, GLONASS (Global Navigation Satellite System), Galileo (Galileo Satellite Navigation System), etc.) receivers, and the two receivers are deployed at different locations.

[0082] The heading angle measured by the dual-station GNSS is integrated with the installation relationship of the laser communication terminal 2 to obtain the initial heading information of the laser communication terminal 2.

[0083] Specifically, first define the carrier coordinate system and the GNSS baseline coordinate system. The carrier coordinate system is defined as the origin of the laser communication terminal 2, the X axis along the carrier longitudinal axis (forward direction), the Y axis perpendicular to the X axis to the right, and the Z axis vertically downward. The GNSS baseline coordinate system is defined by the direction of the line connecting the two antennas (antenna A / antenna B), and the baseline vector is b AB =[Δx L ,Δy L ,Δz L ] T .

[0084] Then measure the installation offset angle, the heading installation offset angle Δψ: the fixed angle between the baseline vector and the carrier's X-axis (needs to be obtained through calibration experiments):

[0085]

[0086] Where, is the horizontal component of the baseline vector in the carrier coordinate system.

[0087] Therefore, the initial heading information of laser communication terminal 2 can be obtained as:

[0088]

[0089] in, It is the heading angle output in real time through dual-station GNSS differential positioning.

[0090] Secondly, the inertial measurement unit arranged on the tethered balloon platform 1 measures the attitude information of the tethered balloon platform 1 in real time, and the attitude information of the laser communication terminal 2 is obtained according to the attitude information.

[0091] Specifically, the inertial measurement unit on the tethered balloon platform 1 is used to measure the platform's attitude information (including pitch angle, roll angle, and yaw angle) in real time. The specific steps include:

[0092] Acquire angular velocity and acceleration data in real time based on the inertial measurement unit;

[0093] According to the angular velocity and acceleration data of the tethered balloon platform 1, combined with the Kalman filter algorithm, the attitude information of the tethered balloon platform 1 is calculated in real time;

[0094] According to the attitude information of the tethered balloon platform 1 and in combination with the installation matrix of the tethered balloon platform 1 and the laser communication terminal 2, the attitude information of the laser communication terminal 2 is determined.

[0095] The installation matrix in this embodiment is the relative installation position of the tethered balloon platform 1 and the laser communication terminal 2. The installation matrix in this embodiment is calculated based on the installation angle. The installation angle includes the orientation between the laser communication terminal 2 and the tethered balloon platform 1. , pitch and roll , roll The coordinate system of the installation angle is the tethered balloon platform coordinate system.

[0096] Furthermore, the coordinate system of the tethered balloon platform is defined as follows: with the center of the tethered balloon platform 1 as the origin, the X-axis is defined as pointing to the front of the tethered balloon platform 1 (i.e., the heading direction); the Y-axis is defined as pointing to the right side of the tethered balloon platform 1; and the Z-axis is defined as perpendicular to the plane of the tethered balloon platform 1 and pointing downward.

[0097] Then, the azimuth angle in the installation angle , pitch angle , roll angle They are defined as follows: the azimuth angle is the rotation angle of the laser communication terminal 2 around the Z axis of the tethered balloon platform coordinate system, which indicates the deflection of the terminal in the horizontal plane; the pitch angle is the rotation angle of the laser communication terminal 2 around the Y axis of the tethered balloon platform coordinate system, which indicates the up and down tilt of the terminal in the vertical plane; the roll angle is the rotation angle of the laser communication terminal 2 around the X axis of the tethered balloon platform coordinate system, which indicates the rotation of the terminal around its own transmitting axis.

[0098] Furthermore, the calculation formula of the installation matrix is:

[0099]

[0100] Where, is the installation matrix, which is the rotation matrix. is the azimuth angle, which represents the rotation angle of the laser communication terminal 2 around the Z axis of the tethered balloon platform coordinate system; is the pitch angle, which represents the rotation angle of the laser communication terminal 2 around the Y axis of the tethered balloon platform coordinate system; is the roll angle, which represents the rotation angle of the laser communication terminal 2 around the X-axis of the tethered balloon platform coordinate system; It is the comprehensive projection of the laser communication terminal 2 on the horizontal and vertical planes; is the projection of the laser communication terminal 2 on the horizontal and vertical planes, is the comprehensive projection of the laser communication terminal 2 in the vertical direction, is the projection of the laser communication terminal 2 on the horizontal plane, is the projection of the laser communication terminal 2 on the horizontal and vertical planes, is the comprehensive projection of the laser communication terminal 2 in the vertical direction, is the projection of the laser communication terminal 2 in the vertical direction, is the comprehensive projection of the laser communication terminal 2 on the horizontal and vertical planes, is the comprehensive projection of the laser communication terminal 2 in the vertical direction, is the unit vector of the laser communication terminal 2 in the X-axis direction of the tethered balloon platform coordinate system, is the unit vector of the laser communication terminal 2 in the Y-axis direction of the tethered balloon platform coordinate system, It is the unit vector of the laser communication terminal 2 in the Z-axis direction of the tethered balloon platform coordinate system; the X-axis in the tethered balloon platform coordinate system is defined as pointing to the heading direction of the tethered balloon platform 1; the Y-axis is defined as pointing to the right side of the tethered balloon platform 1; and the Z-axis is defined as perpendicular to the plane of the tethered balloon platform 1 and pointing downward.

[0101] Assume that the posture of laser communication terminal 2 in the laser communication terminal coordinate system is , then the calculation formula for the attitude information of the laser communication terminal 2 in the tethered balloon platform coordinate system is:

[0102]

[0103] Where, is the attitude information of the tethered balloon platform 1, To install the matrix, It is the posture information of laser communication terminal 2.

[0104] Finally, based on the heading angle and attitude information of the laser communication terminal 2, the initial pointing vector is calculated, and the initial pointing angle of the laser communication terminal 2 is obtained based on the initial pointing vector, where the initial pointing angle includes the azimuth angle and the pitch angle. The specific steps include:

[0105] The GNSS information of the own party and the GNSS information of the other party are obtained from the dual-station GNSS receiver 21, and the GNSS information of the other party is used as the target position.

[0106] The GNSS information in this embodiment is the location information obtained in the GNSS coordinate system, including latitude, longitude and elevation.

[0107] The relative distance and azimuth between the two tethered balloon platforms 1 are calculated based on the GNSS information of the own party and the GNSS information of the other party, and the relative position vector is obtained based on the relative distance and azimuth between the two tethered balloon platforms 1.

[0108] The relative position vector in this embodiment is data in the geodetic coordinate system. To facilitate subsequent calculations, this embodiment first converts the position data of both parties in the geodetic coordinate system to the geocentric rectangular coordinate system. The conversion formula is:

[0109]

[0110] in,

[0111]

[0112] Where, is the Earth's semi-major axis, is the Earth's eccentricity, is the dimension (in radians), is the longitude (in radians), is the elevation, P is the position vector of the laser communication terminal 2, x is the eastward distance of the data point on the earth's surface in the geocentric rectangular coordinate system, y is the northward distance of the data point on the earth's surface in the geocentric rectangular coordinate system, z is the height of the data point on the earth's surface in the geocentric rectangular coordinate system, N is the curvature radius of the normal intercept arc, is the effect of latitude and longitude on easting distance, is the effect of latitude and longitude on northing distance, is a correction term to take into account the spherical shape of the Earth.

[0113] Then, the relative position vector is:

[0114]

[0115] in, is the relative position vector, is the position of the other terminal in the rectangular coordinate system, is the position of your terminal in the rectangular coordinate system.

[0116] The relative position vector is converted into the laser communication terminal coordinate system with the laser communication terminal 2 as the origin to obtain the initial pointing vector of the laser communication terminal 2.

[0117] In this embodiment, the X-axis in the laser communication terminal coordinate system is defined as the emission direction pointing to the laser communication terminal 2; the Y-axis is defined as pointing to the right side of the laser communication terminal 2; and the Z-axis is defined as perpendicular to the plane of the laser communication terminal 2 and pointing downward.

[0118] The relative position vector in the laser communication terminal coordinate system is:

[0119]

[0120] in,

[0121]

[0122] Where, and are the rotation matrices around the Z and Y axes respectively, is the relative position vector in the laser communication terminal coordinate system.

[0123] Then, the initial pointing vector of the laser communication terminal 2 is calculated based on the relative position vector in the laser communication terminal coordinate system:

[0124]

[0125] The initial pointing angle is calculated according to the initial pointing vector, wherein the initial pointing angle includes an azimuth initial pointing angle and an elevation initial pointing angle.

[0126] The initial azimuth pointing angle is:

[0127]

[0128] The initial pointing angle of the pitch angle is:

[0129]

[0130] Where, is the azimuth, and the range is , is the x-axis component of the initial pointing vector, is the y-axis component of the initial pointing vector, is the z-axis component of the initial pointing vector, is the pitch angle, ranging from , is the inverse tangent function.

[0131] After obtaining the initial pointing angle of the laser communication terminal 2, the step of performing error correction on the initial pointing angle is further included, specifically including:

[0132] The calculated initial pointing angle is used as a control command and fed into the turntable control system on the tethered balloon platform 1, which controls the turntable to rotate to the target position. The turntable primarily supports the laser communication terminal 2 and rotates to ensure that the laser beam is incident on the target position, enabling communication. The control accuracy of the turntable directly affects the accuracy of the initial pointing angle, so it is crucial to ensure that the turntable control system can accurately execute the input azimuth and elevation angles.

[0133] Monitor the position of the target tethered balloon platform 1 in real time, compare the monitored position of the target tethered balloon platform 1 with the initial pointing angle, and calculate the error between the current initial pointing angle and the target position;

[0134] An error correction algorithm is used to correct the initial pointing angle, gradually reducing the error. When the error reaches a set threshold, the corrected command angle is used as a control command to rotate the turntable to the target tethered balloon platform 1. Once the error falls within an acceptable range, rapid establishment of the laser communication link is initiated. Rapid scanning and precise tracking technologies ensure the stability and reliability of the laser communication link.

[0135] The error correction algorithm in this embodiment may adopt the least square method or the Kalman filter method.

[0136] In summary, this embodiment eliminates the need for complex star observation or beacon optical systems. By combining dual-station GNSS and an inertial measurement unit, the calculated initial pointing accuracy reaches sub-milliradian levels, significantly improving the efficiency of establishing laser communication links. This method can complete initial pointing and link establishment in a short period of time, making it suitable for emergency communications and rapid response scenarios. Furthermore, it can provide stable reference data under complex meteorological conditions, ensuring high accuracy and stability in dynamic environments.

[0137] Example 2

[0138] A dual-station GNSS receiver 21 is installed on the laser communication terminal 2 body, and the heading angle is measured using differential positioning technology with an accuracy of 0.1°.

[0139] An inertial measurement unit is installed on the tethered balloon platform 1 to measure the platform's attitude information (pitch angle, roll angle, and heading angle) in real time.

[0140] In the carrier coordinate system, the origin is the center of mass of laser communication terminal 2. The X-axis is along the carrier's longitudinal axis (the forward direction), the Y-axis is perpendicular to the X-axis and points to the right, and the Z-axis is vertically downward. The heading angle ψ ranges from 0° to 360° (north is up), the pitch angle θ ranges from -90° to +90° (upward is positive), and the roll angle φ ranges from -180° to +180° (rightward is positive).

[0141] The posture of the laser communication terminal 2 is calculated based on the installation relationship between the laser communication terminal 2 and the tethered balloon platform 1.

[0142] In this embodiment, the GPS information of the user is: . Other party's GPS information: Based on the formula in Example 1, the attitude vector of the laser communication terminal 2 is calculated as v=[0.1, 0.2, 0.3] T .

[0143] Further, calculate the relative position vector and the relative position vector in the platform coordinate system . Calculate the initial pointing vector .

[0144] The initial pointing angle of the laser communication terminal 2 is calculated, where the azimuth angle and pitch angle .

[0145] Set the initial pointing angle and Inputs are sent to the turntable control system to control the turntable's rotation to the target position. Rapid scanning and precise tracking enable rapid establishment of a laser communication link. Error correction algorithms are used to correct the initial pointing angle, gradually reducing errors.

[0146] Example 3

[0147] This embodiment provides a laser communication terminal initial pointing determination system, which is used to implement the laser communication terminal initial pointing determination method in Example 1. The system specifically includes:

[0148] A dual-station GNSS receiver module is deployed on the laser communication terminal 2. The dual-station GNSS receiver 21 module is used to obtain the baseline vector between the two antennas and calculate the heading angle of the laser communication terminal 2 using a differential positioning method based on the baseline vector. The laser communication terminal 2 is installed on the tethered balloon platform 1.

[0149] The specific steps of obtaining the heading angle of the laser communication terminal 2 include:

[0150] The dual-station GNSS receiver 21 synchronously obtains the WGS84 coordinates (World Geodetic System 1984) of the two antennas;

[0151] Convert the WGS84 coordinates of the two antennas to the station center coordinate system, and calculate the baseline vector heading angles of the two antennas in the station center coordinate system;

[0152] Introduce the carrier installation bias to correct the baseline vector heading angle:

[0153] The Kalman filter is used to fuse multiple sets of differential observations to dynamically compensate the corrected baseline heading angle to obtain the heading angle of the laser communication terminal 2.

[0154] For example, Figure 2 As shown, the dual-station GNSS receiver 21 synchronously obtains the WGS84 coordinates of antenna A and antenna B: wherein, the coordinates of antenna A point are: , coordinates of antenna point B: ( ).

[0155] The WGS84 coordinates of the two antennas are converted to the station center coordinate system. The specific conversion formula is:

[0156]

[0157]

[0158]

[0159] Where, is the radius of curvature of the y-axis, e is the eccentricity of the earth, is the coordinate difference of the station center coordinate system in the x direction caused by the longitude difference, is the latitude of antenna A, is the longitude of antenna A, is the ellipsoidal elevation of antenna A, W is the latitude of antenna B, is the longitude of antenna B, is the ellipsoidal elevation of antenna B, is the coordinate difference in the y direction of the station center coordinate system caused by the latitude difference, is the coordinate difference in the z direction of the station center coordinate system corresponding to the height difference. To convert the latitude of antenna A into the x-direction component in the station center coordinate system, To convert the latitude of antenna A into the y-direction component in the station center coordinate system.

[0160] Furthermore, the calculation expression corresponding to the baseline vector heading angle is:

[0161]

[0162] Where, is the heading angle of the baseline vector. hour, .when hour, .

[0163] After the carrier installation bias correction is introduced, the calculation expression of the baseline vector heading angle is:

[0164]

[0165] Where, is the heading angle of the baseline vector after correction, is the baseline vector The theoretical installation deviation angle from the longitudinal axis of the carrier.

[0166] The Kalman filter is used to fuse multiple sets of differential observations and iteratively update them using the following formula:

[0167]

[0168] Where, is the estimated state value at the kth moment, is the estimated state value at the k-1th moment, is the observed value at the kth moment, is the observation matrix, is the Kalman gain at the kth moment.

[0169] The dual-station GNSS receiver 21 refers to a collaborative working system composed of two GNSS (Global Navigation Satellite System, such as GPS (Global Positioning System), Beidou, GLONASS (Global Navigation Satellite System), Galileo (Galileo Satellite Navigation System), etc.) receivers, and the two receivers are deployed at different locations.

[0170] The heading angle measured by the dual-station GNSS is integrated with the installation relationship of the laser communication terminal 2 to obtain the initial heading information of the laser communication terminal 2.

[0171] Specifically, first define the carrier coordinate system and the GNSS baseline coordinate system. The carrier coordinate system is defined as the origin of the laser communication terminal 2, the X axis along the carrier longitudinal axis (forward direction), the Y axis perpendicular to the X axis to the right, and the Z axis vertically downward. The GNSS baseline coordinate system is defined by the direction of the line connecting the two antennas (antenna A / antenna B), and the baseline vector is b AB =[Δx L ,Δy L ,Δz L ] T .

[0172] Then measure the installation offset angle, the heading installation offset angle Δψ: the fixed angle between the baseline vector and the carrier's X-axis (needs to be obtained through calibration experiments):

[0173]

[0174] Where, is the horizontal component of the baseline vector in the carrier coordinate system.

[0175] Therefore, the initial heading information of laser communication terminal 2 can be obtained as:

[0176]

[0177] in, It is the heading angle output in real time through dual-station GNSS differential positioning.

[0178] An inertial measurement unit is provided on the tethered balloon platform 1; wherein the inertial measurement unit measures the attitude information of the tethered balloon platform 1 in real time, and obtains the attitude information of the laser communication terminal 2 based on the attitude information;

[0179] The inertial measurement unit on the tethered balloon platform 1 is used to measure the platform's attitude information (including pitch angle, roll angle, and yaw angle) in real time. The specific steps include:

[0180] Acquire angular velocity and acceleration data in real time based on the inertial measurement unit;

[0181] According to the angular velocity and acceleration data of the tethered balloon platform 1, combined with the Kalman filter algorithm, the attitude information of the tethered balloon platform 1 is calculated in real time;

[0182] According to the attitude information of the tethered balloon platform 1 and in combination with the installation matrix of the tethered balloon platform 1 and the laser communication terminal 2, the attitude information of the laser communication terminal 2 is determined.

[0183] The installation matrix in this embodiment is the relative installation position of the tethered balloon platform 1 and the laser communication terminal 2. The installation matrix in this embodiment is calculated based on the installation angle. The installation angle includes the orientation between the laser communication terminal 2 and the tethered balloon platform 1. , pitch and roll , roll The coordinate system of the installation angle is the tethered balloon platform coordinate system.

[0184] Furthermore, the coordinate system of the tethered balloon platform is defined as follows: with the center of the tethered balloon platform 1 as the origin, the X-axis is defined as pointing to the front of the tethered balloon platform 1 (i.e., the heading direction); the Y-axis is defined as pointing to the right side of the tethered balloon platform 1; and the Z-axis is defined as perpendicular to the plane of the tethered balloon platform 1 and pointing downward.

[0185] Then, the azimuth angle in the installation angle , pitch angle , roll angle They are defined as follows: the azimuth angle is the rotation angle of the laser communication terminal 2 around the Z axis of the tethered balloon platform coordinate system, which indicates the deflection of the terminal in the horizontal plane; the pitch angle is the rotation angle of the laser communication terminal 2 around the Y axis of the tethered balloon platform coordinate system, which indicates the up and down tilt of the terminal in the vertical plane; the roll angle is the rotation angle of the laser communication terminal 2 around the X axis of the tethered balloon platform coordinate system, which indicates the rotation of the terminal around its own transmitting axis.

[0186] Furthermore, the calculation formula of the installation matrix is:

[0187]

[0188] Where, is the installation matrix, which is the rotation matrix. is the azimuth angle, which represents the rotation angle of the laser communication terminal 2 around the Z axis of the tethered balloon platform coordinate system; is the pitch angle, which represents the rotation angle of the laser communication terminal 2 around the Y axis of the tethered balloon platform coordinate system; is the roll angle, which represents the rotation angle of the laser communication terminal 2 around the X-axis of the tethered balloon platform coordinate system; It is the comprehensive projection of the laser communication terminal 2 on the horizontal and vertical planes; is the projection of the laser communication terminal 2 on the horizontal and vertical planes, is the comprehensive projection of the laser communication terminal 2 in the vertical direction, is the projection of the laser communication terminal 2 on the horizontal plane, is the projection of the laser communication terminal 2 on the horizontal and vertical planes, is the comprehensive projection of the laser communication terminal 2 in the vertical direction, is the projection of the laser communication terminal 2 in the vertical direction, is the comprehensive projection of the laser communication terminal 2 on the horizontal and vertical planes, is the comprehensive projection of the laser communication terminal 2 in the vertical direction, is the unit vector of the laser communication terminal 2 in the X-axis direction of the tethered balloon platform coordinate system, is the unit vector of the laser communication terminal 2 in the Y-axis direction of the tethered balloon platform coordinate system, It is the unit vector of the laser communication terminal 2 in the Z-axis direction of the tethered balloon platform coordinate system; the X-axis in the tethered balloon platform coordinate system is defined as pointing to the heading direction of the tethered balloon platform 1; the Y-axis is defined as pointing to the right side of the tethered balloon platform 1; and the Z-axis is defined as perpendicular to the plane of the tethered balloon platform 1 and pointing downward.

[0189] Assume that the posture of laser communication terminal 2 in the laser communication terminal coordinate system is , then the calculation formula for the attitude information of the laser communication terminal 2 in the tethered balloon platform coordinate system is:

[0190]

[0191] Where, is the attitude information of the tethered balloon platform 1, To install the matrix, It is the posture information of laser communication terminal 2.

[0192] The initial pointing angle determination module calculates the initial pointing vector based on the heading angle and attitude information of the laser communication terminal 2, and obtains the initial pointing angle of the laser communication terminal 2 based on the initial pointing vector. The initial pointing angle includes the azimuth angle and the pitch angle.

[0193] The initial pointing angle includes azimuth and elevation. The specific steps are:

[0194] The GNSS information of the own party and the GNSS information of the other party are obtained from the dual-station GNSS receiver 21, and the GNSS information of the other party is used as the target position.

[0195] The GNSS information in this embodiment is the location information obtained in the GNSS coordinate system, including latitude, longitude and elevation.

[0196] The relative distance and azimuth between the two tethered balloon platforms 1 are calculated based on the GNSS information of the own party and the GNSS information of the other party, and the relative position vector is obtained based on the relative distance and azimuth between the two tethered balloon platforms 1.

[0197] The relative position vector in this embodiment is data in the geodetic coordinate system. To facilitate subsequent calculations, this embodiment first converts the position data of both parties in the geodetic coordinate system to the geocentric rectangular coordinate system. The conversion formula is:

[0198]

[0199] in,

[0200]

[0201] Where, is the Earth's semi-major axis, is the Earth's eccentricity, is the dimension (in radians), is the longitude (in radians), is the elevation, P is the position vector of the laser communication terminal 2, x is the eastward distance of the data point on the earth's surface in the geocentric rectangular coordinate system, y is the northward distance of the data point on the earth's surface in the geocentric rectangular coordinate system, z is the height of the data point on the earth's surface in the geocentric rectangular coordinate system, N is the curvature radius of the normal intercept arc, is the effect of latitude and longitude on easting distance, is the effect of latitude and longitude on northing distance, is a correction term to take into account the spherical shape of the Earth.

[0202] Then, the relative position vector is:

[0203]

[0204] in, is the relative position vector, is the position of the other terminal in the rectangular coordinate system, is the position of your terminal in the rectangular coordinate system.

[0205] The relative position vector is converted into the laser communication terminal coordinate system with the laser communication terminal 2 as the origin to obtain the initial pointing vector of the laser communication terminal 2.

[0206] In this embodiment, the X-axis in the laser communication terminal coordinate system is defined as the emission direction pointing to the laser communication terminal 2; the Y-axis is defined as pointing to the right side of the laser communication terminal 2; and the Z-axis is defined as perpendicular to the plane of the laser communication terminal 2 and pointing downward.

[0207] The relative position vector in the laser communication terminal coordinate system is:

[0208]

[0209] in,

[0210]

[0211] Where, and are the rotation matrices around the Z and Y axes respectively, is the relative position vector in the laser communication terminal coordinate system.

[0212] Then, the initial pointing vector of the laser communication terminal 2 is calculated based on the relative position vector in the laser communication terminal coordinate system:

[0213]

[0214] The initial pointing angle is calculated according to the initial pointing vector, wherein the initial pointing angle includes an azimuth initial pointing angle and an elevation initial pointing angle.

[0215] The initial azimuth pointing angle is:

[0216]

[0217] The initial pointing angle of the pitch angle is:

[0218]

[0219] Where, is the azimuth, and the range is , is the x-axis component of the initial pointing vector, is the y-axis component of the initial pointing vector, is the z-axis component of the initial pointing vector, is the pitch angle, ranging from , is the inverse tangent function.

[0220] After obtaining the initial pointing angle of the laser communication terminal 2, the error correction of the initial pointing angle is further performed, specifically including:

[0221] The calculated initial pointing angle is used as a control command and fed into the turntable control system on the tethered balloon platform 1, which controls the turntable to rotate to the target position. The turntable primarily supports the laser communication terminal 2 and rotates to ensure that the laser beam is incident on the target position, enabling communication. The control accuracy of the turntable directly affects the accuracy of the initial pointing angle, so it is crucial to ensure that the turntable control system can accurately execute the input azimuth and elevation angles.

[0222] Monitor the position of the target tethered balloon platform 1 in real time, compare the monitored position of the target tethered balloon platform 1 with the initial pointing angle, and calculate the error between the current initial pointing angle and the target position;

[0223] An error correction algorithm is used to correct the initial pointing angle, gradually reducing the error. When the error reaches a set threshold, the corrected command angle is used as a control command to rotate the turntable to the target tethered balloon platform 1. Once the error falls within an acceptable range, rapid establishment of the laser communication link is initiated. Rapid scanning and precise tracking technologies ensure the stability and reliability of the laser communication link.

[0224] The error correction algorithm in this embodiment may adopt the least square method or the Kalman filter method.

[0225] In summary, this embodiment eliminates the need for complex star observation or beacon optical systems. By combining dual-station GNSS and an inertial measurement unit, the calculated initial pointing accuracy reaches sub-milliradian levels, significantly improving the efficiency of establishing laser communication links. This method can complete initial pointing and link establishment in a short period of time, making it suitable for emergency communications and rapid response scenarios. Furthermore, it can provide stable reference data under complex meteorological conditions, ensuring high accuracy and stability in dynamic environments.

[0226] Example 4

[0227] In another embodiment of the present invention, a computer-readable storage medium is provided as a storage component within a terminal device, the function of which is to store programs and data. It should be noted that the computer-readable storage medium herein encompasses not only the built-in storage component of the terminal device, but also the extended storage component supported by the device. Essentially, it is a tangible medium that can contain or store programs that can be called by, or run in conjunction with, an instruction execution system, device, or component. This storage medium provides a storage area for the terminal's operating system and stores one or more instructions suitable for loading and executing by the processor. These instructions can constitute one or more computer programs containing program code.

[0228] In particular, examples (a non-exclusive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable magnetic disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, optical fiber, a portable optical disc read-only memory, an optical storage device, a magnetic storage device, or any reasonable combination of the foregoing.

[0229] The storage medium may also include a data signal transmitted as part of a baseband portion or carrier wave, which carries readable program code. Such a transmitted data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any reasonable combination of the two. In addition, computer-readable storage media may also refer to other readable media other than traditional readable storage media, which are capable of sending, transmitting, or transmitting programs for use by or in conjunction with an instruction execution system, device, or device. The program code on the storage medium may be transmitted via any suitable medium, including but not limited to wireless, wired, optical cable, or any reasonable combination thereof.

[0230] The program code used to implement the operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as "C." The program code can be executed entirely on the user's computing device, partially on the user's device as a standalone software package, partially distributed across the user's device and a remote computing device, or entirely on a remote computing device or server. When a remote computing device is involved, the device may be connected to the user's computing device via any type of network, such as a local area network or wide area network, or connected to an external computing device via the Internet through an Internet service provider.

[0231] The processor is capable of loading and executing one or more instructions stored in a computer-readable storage medium to implement the corresponding steps of the method for determining the initial pointing direction of a laser communication terminal described in Example 1.

[0232] Example 5

[0233] Reference Figure 4 Another embodiment of the present invention provides a terminal device, which is specifically a computer device 60. This computer device 60 is mainly composed of three parts, namely a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and capable of running on the processor 61. Among them, the responsibility of the processor 61 is to execute the computer program to implement the method for determining the initial pointing of the laser communication terminal described in Example 1. The memory 62 is used to store computer programs and other programs and data required for the operation of the device. When the computer program 63 runs on the processor 61, it can implement the method for determining the initial pointing of the laser communication terminal. In order to avoid repetition of content, the relevant details will not be described in detail here.

[0234] The computer device 60 has many different forms. It can be a desktop computer, a notebook computer, a handheld computer, or a computing device such as a cloud server.

[0235] The processor 61 may be a central processing unit, or other types of general-purpose processors, central processing units, graphics processing units, digital signal processors, application-specific integrated circuits, field programmable gate arrays, or other programmable logic devices, discrete gate or transistor logic devices, quantum computing-based data processing logic, discrete hardware components, etc. The general-purpose processor referred to herein refers to a microprocessor or any conventional processor.

[0236] Memory 62 can be an internal storage unit of computer device 60, such as its hard drive or memory, or an external storage device, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) card, or flash memory card. Memory 62 not only stores computer programs but also other programs and data required for device operation, and temporarily stores data that has been or is about to be output.

[0237] In the various embodiments provided herein, references to memory, databases, or other media will encompass at least one of non-volatile memory and volatile memory. There are many types of non-volatile memory, including read-only memory, magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory, magnetic random access memory, ferroelectric memory, phase change memory, graphene memory, and the like. Volatile memory may include random access memory (RAM) or external cache memory. It should be noted that RAM has various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

Claims

1. A method for determining the initial pointing direction of a laser communication terminal, characterized in that: include: A dual-station GNSS receiver deployed on a laser communication terminal is used to obtain a baseline vector between two antennas, and a heading angle of the laser communication terminal is calculated based on the baseline vector using a differential positioning method; the laser communication terminal is mounted on a tethered balloon platform; The inertial measurement unit provided on the tethered balloon platform measures the attitude information of the tethered balloon platform in real time, and obtains the attitude information of the laser communication terminal according to the attitude information. The specific steps are as follows: Acquire angular velocity and acceleration data in real time based on the inertial measurement unit; According to the angular velocity and acceleration data of the tethered balloon platform, the attitude information of the tethered balloon platform is obtained in combination with a Kalman filter algorithm, wherein the attitude information includes a pitch angle, a roll angle, and a yaw angle; Determining the attitude information of the laser communication terminal based on the attitude information of the tethered balloon platform and the installation matrix of the tethered balloon platform and the laser communication terminal, wherein the installation matrix is ​​the relative installation positions of the tethered balloon platform and the laser communication terminal; An initial pointing vector is calculated based on the heading angle and attitude information of the laser communication terminal, and an initial pointing angle of the laser communication terminal is obtained based on the initial pointing vector. The initial pointing angle includes an azimuth angle and a pitch angle.

2. The method for determining the initial pointing direction of a laser communication terminal according to claim 1, wherein: The heading angle of the laser communication terminal is calculated using the differential positioning method based on the baseline vector, specifically including: The dual-station GNSS receivers synchronously obtain the WGS84 coordinates of the two antennas; convert the WGS84 coordinates of the two antennas to the station-centered coordinate system, and calculate the baseline vector heading angles of the two antennas in the station-centered coordinate system; Introduce the carrier installation bias to correct the baseline vector heading angle: The Kalman filter is used to fuse multiple sets of differential observations to dynamically compensate the corrected baseline heading angle and obtain the heading angle of the laser communication terminal.

3. The method for determining the initial pointing direction of a laser communication terminal according to claim 1, wherein: The calculation formula of the installation matrix is: Where, To install the matrix, is the azimuth, which represents the rotation angle of the laser communication terminal around the Z axis of the tethered balloon platform coordinate system; is the pitch angle, which represents the rotation angle of the laser communication terminal around the Y axis of the tethered balloon platform coordinate system; is the roll angle, which represents the rotation angle of the laser communication terminal around the X-axis of the tethered balloon platform coordinate system; It is the comprehensive projection of the laser communication terminal on the horizontal and vertical planes; is the projection of the laser communication terminal on the horizontal and vertical planes, It is the comprehensive projection of the laser communication terminal in the vertical direction. is the projection of the laser communication terminal on the horizontal plane, is the projection of the laser communication terminal on the horizontal and vertical planes, It is the comprehensive projection of the laser communication terminal in the vertical direction. is the projection of the laser communication terminal in the vertical direction, It is the comprehensive projection of the laser communication terminal on the horizontal and vertical planes. It is the comprehensive projection of the laser communication terminal in the vertical direction. is the unit vector of the laser communication terminal in the X-axis direction of the tethered balloon platform coordinate system, is the unit vector of the laser communication terminal in the Y-axis direction of the tethered balloon platform coordinate system, is the unit vector of the laser communication terminal in the Z-axis direction of the tethered balloon platform coordinate system; the X-axis in the tethered balloon platform coordinate system is defined as pointing in the heading direction of the tethered balloon platform; and the Y-axis is defined as pointing to the right side of the tethered balloon platform; The Z axis is defined as perpendicular to the plane of the tethered balloon platform and points downward.

4. The method for determining the initial pointing direction of a laser communication terminal according to claim 3, wherein: The calculation formula of the attitude information of the laser communication terminal is: Where, is the attitude information of the tethered balloon platform, To install the matrix, It is the attitude information of the laser communication terminal.

5. The method for determining the initial pointing direction of a laser communication terminal according to claim 1, wherein: The calculation of the initial pointing vector based on the heading angle and attitude information of the laser communication terminal specifically includes: Obtain the GNSS information of the own party and the other party from the dual-station GNSS receiver; Calculate the relative distance and azimuth between the two tethered balloon platforms based on the GNSS information of the own party and the GNSS information of the other party, and obtain the relative position vector based on the relative distance and azimuth between the two tethered balloon platforms; Converting the relative position vector to a laser communication terminal coordinate system with the laser communication terminal as the origin to obtain an initial pointing vector of the laser communication terminal; The X-axis in the laser communication terminal coordinate system is defined as pointing to the emission direction of the laser communication terminal; the Y-axis is defined as pointing to the right side of the laser communication terminal; and the Z-axis is defined as perpendicular to the plane of the laser communication terminal and pointing downward.

6. The method for determining the initial pointing direction of a laser communication terminal according to claim 5, wherein: The initial pointing angle of the laser communication terminal is obtained according to the initial pointing vector. The calculation formula of the initial pointing angle is: Where, is the azimuth, is the x-axis component of the initial pointing vector, is the y-axis component of the initial pointing vector, is the z-axis component of the initial pointing vector, is the pitch angle, is the inverse tangent function.

7. The method for determining the initial pointing direction of a laser communication terminal according to claim 1, wherein: After obtaining the initial pointing angle of the laser communication terminal, the method further includes performing error correction on the initial pointing angle, specifically including: The calculated initial pointing angle is input as a control instruction to a turntable control system on the tethered balloon platform to control the turntable in the turntable control system to rotate to a target position; Monitor the target tethered balloon platform position in real time, compare the monitored target tethered balloon platform position with the initial pointing angle, and calculate the error between the current initial pointing angle and the target position; An error correction algorithm is used to correct the initial pointing angle. When the error reaches a set threshold, the corrected instruction angle is used as a control instruction to control the turntable to rotate to the target tethered balloon platform position.

8. A laser communication terminal initial pointing determination system, used to implement the laser communication terminal initial pointing determination method according to any one of claims 1 to 7, characterized in that: include: Dual-station GNSS receiver module, deployed on the laser communication terminal; The dual-station GNSS receiver module is used to obtain a baseline vector between two antennas and calculate the heading angle of the laser communication terminal using a differential positioning method based on the baseline vector; the laser communication terminal is mounted on a tethered balloon platform; An inertial measurement unit is provided on the tethered balloon platform; the inertial measurement unit measures attitude information of the tethered balloon platform in real time, and obtains attitude information of the laser communication terminal based on the attitude information; The initial pointing angle determination module calculates an initial pointing vector based on the heading angle and attitude information of the laser communication terminal, and obtains the initial pointing angle of the laser communication terminal based on the initial pointing vector. The initial pointing angle includes an azimuth angle and a pitch angle.

9. A computing device, characterized in that include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include a method for executing the initial pointing determination method of the laser communication terminal according to any one of claims 1 to 7.

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