Initial pointing implementation method of movable ground laser communication terminal

Abstract

The invention discloses an initial pointing implementation method of a movable ground laser communication terminal. The method comprises the following steps: carrying out initialization; the two-dimensional rotary table returns to zero; after receiving the local position and attitude data, interrupting the serial port; analyzing local position and attitude information; calculating a directional angle to obtain an outer ring angle and an inner ring angle which need to be rotated by the two-dimensional turntable; and controlling the two-dimensional turntable to rotate to a corresponding pointing angle position according to an outer ring angle and an inner ring angle of the two-dimensional turntable, judging whether target light points to a target at a CCD light spot position, if so, finishing initial pointing of the target, and if not, continuing to rotate the two-dimensional turntable according to a deviation position calculation result to finish initial pointing of the target. The pointing angle is obtained by resolving real-time data of satellite positioning, and then the rotary table is controlled to rotate to achieve visual axis pointing of the two communication parties.

Description

Technical Field

[0001] The invention belongs to the technical field of optical communication equipment, and in particular relates to a method for realizing initial pointing of a movable ground laser communication terminal. Background Art

[0002] Laser communication has outstanding advantages such as high transmission rate, large communication capacity, good confidentiality, strong anti-interference ability, small size, light weight and low power consumption. However, the problem of line of sight pointing of laser communication terminals has always been the focus and difficulty in the field of space laser communication. The premise of establishing a laser communication link is that both communicating parties can quickly capture and achieve line of sight alignment. The initial line of sight pointing, as the first step in the capture system, determines whether the capture can be successful, the probability of capture and the length of capture time. Therefore, in order to achieve high-precision line of sight pointing, thereby providing guarantees for capture, alignment and tracking, it is necessary to achieve real-time and accurate analysis of the attitude and position information of both communicating parties on the basis of ensuring the stability of the line of sight. Summary of the invention

[0003] The purpose of the present invention is to provide a method for realizing initial pointing of a movable ground laser communication terminal, which obtains the pointing angle by solving the real-time data of satellite positioning, and then controls the rotation of the turntable to realize the line of sight pointing of the communicating parties.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A method for realizing initial pointing of a movable ground laser communication terminal comprises the following steps:

[0006] S1, initialization;

[0007] S2, 2D turntable zeroing;

[0008] S3, after receiving the local position and posture data, the serial port is interrupted;

[0009] S4, parsing local position and posture information;

[0010] S5, calculating the pointing angle, and obtaining the outer ring angle and the inner ring angle that the two-dimensional turntable needs to rotate;

[0011] S6, control the two-dimensional turntable to rotate to the corresponding pointing angle position according to the outer ring angle and inner ring angle that the two-dimensional turntable needs to rotate, and judge whether it is pointing to the target through the target light at the CCD spot position. If yes, the initial pointing of the target is completed. If not, continue to rotate the two-dimensional turntable according to the deviation position calculation result to complete the initial pointing of the target.

[0012] Preferably, in S3, the global navigation system / inertial navigation system combination module corrects the drift caused by the inertial navigation system through the global navigation system, and when the global navigation system fails to work, the inertial navigation system takes over the work of the global navigation system.

[0013] Preferably, the specific step of S4 is: obtaining the azimuth and pitch angle through the local position, attitude information, and target ephemeris.

[0014] Preferably, the specific steps of S5 are:

[0015] S501, angle translation, to obtain an azimuth angle Az' and an elevation angle El' after the angle translation;

[0016] S502, according to S501, obtain the outer ring angle θ O and the inner ring angle θ I ;

[0017] S503, perform horizontal correction on S502 to obtain the outer ring angle θ' after horizontal correction O and the horizontally corrected inner ring angle θ' I ;

[0018] S504, perform zero position correction on S503 to obtain the outer ring angle θ that the two-dimensional turntable needs to rotate." O and the inner ring angle θ that the two-dimensional turntable needs to rotate I .

[0019] Preferably, in S501, the specific formula for calculating the azimuth angle Az' after the angle translation and the elevation angle El' after the angle translation is:

[0020]

[0021] El'=El

[0022] Among them, Az is the azimuth in the northeast sky coordinate system, El is the elevation angle in the northeast sky coordinate system, and α is the X GPS The angle with Xt, β is X GPS Angle with Yd, X GPS It is the vector direction from the main antenna to the auxiliary antenna in the GPS antenna coordinate system on the station, Xt is the reducer side pointing to the center of the outer frame in the vehicle station coordinate system, and Yd is due north in the northeast sky coordinate system.

[0023] Preferably, in S502, the outer ring angle θ is calculated O and the inner ring angle θ I The specific formula is:

[0024]

[0025] Among them, Az' is the azimuth after angle translation, El' is the pitch angle after angle translation, and x, y, and z are the three-dimensional coordinates of the vector between the satellite and the movable ground laser communication terminal.

[0026] Preferably, in S503, the outer ring angle θ' after horizontal correction is calculated O and the horizontally corrected inner ring angle θ' I The specific formula is:

[0027]

[0028] Among them, θ O is the outer ring angle, θ I is the inner ring angle, γ y is the angle of the Yt azimuth measured by the level instrument, γ x is the angle of the Xt azimuth measured by the level instrument, Xt is the reducer side pointing to the center of the outer frame in the vehicle-mounted station coordinate system, and Yt is the reducer motor side pointing to the center of the inner frame in the vehicle-mounted station coordinate system.

[0029] Preferably, in S504, the outer ring angle θ that the two-dimensional turntable needs to rotate is calculated. O and the inner ring angle θ that the two-dimensional turntable needs to rotate I The specific formula is:

[0030]

[0031] in, is the code disk value of the outer ring in the terminal reference state, is the code disk value of the inner ring in the terminal reference state, θ' O is the outer ring angle after horizontal correction, θ' I is the inner ring angle after horizontal correction.

[0032] The beneficial effect of the present invention is that the pointing angle is obtained by solving the real-time data of satellite positioning, and then the rotation of the turntable is controlled to realize the line of sight pointing of the communicating parties. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the present invention.

[0034] Figure 2 The hardware block diagram of the aiming process, wherein 1 is a computer controller, 2 is a global navigation system / inertial navigation system combination module (GNSS / INS combination module), 3 is a level, and 4 is a two-dimensional turntable.

[0035] Figure 3 is the vehicle station coordinate system.

[0036] Figure 4It is the coordinate system of the GPS antenna on the station.

[0037] Figure 5 It is the northeast celestial coordinate system.

[0038] Figure 6 For the aiming calculation process. DETAILED DESCRIPTION

[0039] At a specified time, the mobile ground laser communication terminal controls the optical antenna to point to the communication (target) satellite and maintains the direction to the communication (target) satellite at a specified time. Figure 2 As shown, an initial pointing of a movable ground laser communication terminal includes a computer controller 1, a global navigation system / inertial navigation system combination module (GNSS / INS combination module) 2, a level 3, a two-dimensional turntable 4, and a charge-coupled device camera (CCD camera).

[0040] Computer controller 1: It consists of an industrial computer and a controller board, and is installed with corresponding control software. It generates pointing data using GNSS / INS data, uses a level to make corrections, and outputs inner and outer ring data to drive the two-dimensional turntable.

[0041] Global Navigation System / Inertial Navigation System Combined Module (GNSS / INS Combined Module) 2: used to obtain local position (longitude, latitude and altitude) and attitude information (heading angle (north-east angle)).

[0042] Charge-coupled device camera (CCD camera): used to observe the beacon light spot position of the target.

[0043] Level 3: Measures the horizontal inclination along the terminal's outer axis (long axis) and inner axis (short axis), and is used for the vehicle-mounted station to correct the horizontal angle of the satellite pointing angle.

[0044] 2D turntable 4: executes and drives the antenna to point to the target position.

[0045] like Figure 1-Figure 6 As shown, a method for realizing initial pointing of a movable ground laser communication terminal comprises the following steps:

[0046] S1, the computer controller initializes each module.

[0047] S2, the computer controller returns the two-dimensional turntable to zero.

[0048] S3, when the computer controller receives the local position and attitude data sent by the global navigation system / inertial navigation system combination module, the serial port is interrupted.

[0049] The GNSS / INS combination module and the computer controller use serial communication. The GNSS / INS combination module obtains the local position (longitude, latitude and altitude) and attitude information (heading angle (north-east angle)) in real time. When the computer controller receives the local position and attitude data sent by the GNSS / INS combination module, a serial port interrupt is generated.

[0050] When the computer controller does not receive the local position and attitude data sent by the GNSS / INS combination module, it continues to receive the local position and attitude data sent by the GNSS / INS combination module, and then the serial port is interrupted.

[0051] The global navigation system / inertial navigation system combination module (GNSS / INS combination module) corrects the drift caused by the inertial navigation system (INS) through the global navigation system (GNSS) to improve the measurement accuracy of the system. When the global navigation system (GNSS) cannot work due to signal interference or obstruction, the inertial navigation system (INS) takes over the global navigation system (GNSS) to work, thereby improving the reliability of the system.

[0052] S4, the computer controller analyzes the local position and attitude information (GPS data).

[0053] The local position (latitude and longitude), attitude information, and target ephemeris are imported into the computer controller to obtain the pointing angle sequence from the vehicle-mounted station to the satellite in the next orbit (time t, azimuth angle Az and elevation angle El in polar coordinates).

[0054] S5, the computer controller calculates the pointing angle according to the pointing algorithm to obtain the outer ring and inner ring angles that the two-dimensional turntable needs to rotate.

[0055] Coordinate system definition:

[0056] Vehicle station coordinate system: Figure 3 , through the center of the middle frame, the reducer side pointing to the center of the outer frame is Xt, the reducer motor side pointing to the center of the inner frame is Yt, and the antenna optical axis is Zt, where the outer ring angle (angle around the outer frame) is θ O , the inner ring angle (angle around the inner frame) is θ I , when θ O ,θ I At 0°, the antenna points vertically upward.

[0057] GPS antenna coordinate system on the station: Figure 4 , obtained by the GPS on the station, the vector direction from the main antenna to the secondary antenna, the vector is X GPS , the vector is in the XtYt plane of the vehicle-mounted station coordinate system. In the design, it is installed along the outer axis of the ground antenna, from the side without the reducer to the side with the reducer. Assuming that XGPS With Xt at an angle α, such as Figure 5 ShownX GPS The inside of Xt is positive and the outside is negative.

[0058] Northeastern celestial coordinate system: Figure 5 , due east is Xd, due north is Yd, vertical upward is Zd, given the vector r's Az and El, where the zero point of Az is the angle between the projection of r on the XdYd plane and Yd, and El is the plane angle between vector r and XdY, where under the top-down condition, X GPS To the right of Yd is positive and to the left is negative.

[0059] The aiming calculation process is as follows Figure 6 As shown:

[0060] S501, angle translation, to obtain an azimuth angle Az' after the angle translation and an elevation angle El' after the angle translation.

[0061] In the northeast sky coordinate system, the azimuth and elevation angles of the given target are Az and El. Assuming that under the leveling condition, the northeast sky coordinate system and the vehicle-mounted station coordinate system (transitional coordinate system, without horizontal correction) only rotate around the Z axis, then in the transitional coordinate system, the azimuth angle Az' and the elevation angle El' after the angle translation are:

[0062]

[0063] Among them, Az is the azimuth in the northeast sky coordinate system, El is the elevation angle in the northeast sky coordinate system, and α is the X GPS The angle with Xt, β is X GPS Angle with Yd, X GPS It is the vector direction from the main antenna to the auxiliary antenna in the GPS antenna coordinate system on the station, Xt is the reducer side pointing to the center of the outer frame in the vehicle station coordinate system, and Yd is due north in the northeast sky coordinate system.

[0064] S502, according to S501, obtain the outer ring angle θ O and the inner ring angle θ I .

[0065] For vector r, the azimuth and elevation angles are used to characterize it, and the results are as follows:

[0066]

[0067] Among them, Az' is the azimuth angle after angle translation, and El' is the elevation angle after angle translation.

[0068] Converted to outer ring angle θ O and the inner ring angle θ I as follows:

[0069]

[0070] Among them, Az' is the azimuth after angle translation, El' is the pitch angle after angle translation, and x, y, and z are the three-dimensional coordinates of the vector between the satellite and the movable ground laser communication terminal.

[0071] S503, perform horizontal correction on S502 to obtain the outer ring angle θ' after horizontal correction O and the horizontally corrected inner ring angle θ' I .

[0072] The horizontality of the vehicle station Xt and Yt can be obtained by the level meter. Assuming that the measurement result obtained by the level meter is positive upward and negative downward relative to the positive direction of Xt / Yt, then the inner ring angle of the Xt azimuth minus γ x (Similarly, the outer ring in the Yt direction minus γ y ), that is, the outer ring angle θ' after horizontal correction O and the horizontally corrected inner ring angle θ' I for:

[0073]

[0074] Among them, θ O is the outer ring angle, θ I is the inner ring angle, γ y is the angle of the Yt azimuth measured by the level instrument, γ x is the angle of the Xt azimuth measured by the level instrument, Xt is the reducer side pointing to the center of the outer frame in the vehicle-mounted station coordinate system, and Yt is the reducer motor side pointing to the center of the inner frame in the vehicle-mounted station coordinate system.

[0075] S504, perform zero position correction on S503 to obtain the outer ring angle θ that the two-dimensional turntable needs to rotate." O and the inner ring angle θ that the two-dimensional turntable needs to rotate I .

[0076] Knowing the θ' calculated by the front end O and θ' I The outer ring and inner ring are both 0° in the vehicle station reference state. In practice, the installation of the encoder will cause a certain angle shift, and necessary shift correction is required. The outer ring angle θ that the two-dimensional turntable needs to rotate is O and the inner ring angle θ" I The calculation formula is:

[0077]

[0078] in, is the code disk value of the outer ring in the terminal reference state, is the code disk value of the inner ring in the terminal reference state, θ' O is the outer ring angle after horizontal correction, θ' I is the inner ring angle after horizontal correction.

[0079] S6, the computer controller generates a turntable rotation instruction according to the outer ring angle and the inner ring angle that the two-dimensional turntable needs to rotate, and issues a rotation instruction to control the two-dimensional turntable to rotate to the corresponding pointing angle position, and judges whether it is pointing to the target through the target light at the CCD spot position. If yes, the initial pointing of the target is completed. If not, the two-dimensional turntable continues to rotate according to the deviation position calculation result to complete the initial pointing of the target.

[0080] The computer controller generates a turntable rotation command based on the angles of the outer ring and the inner ring. After issuing the rotation command to control the inner ring motor and the outer ring motor of the two-dimensional turntable to rotate to the corresponding pointing angle position, the CCD camera receives the beacon light signal. After image processing, the CCD data is transmitted to the computer controller. The computer controller makes a judgment. If the beacon light spot is located at the CCD specified position, the initial pointing of the target is completed.

[0081] If the beacon light spot is biased towards the CCD specified position, the CCD data is processed by the computer controller to control the inner and outer ring motors to rotate and adjust the inner and outer ring angles of the two-dimensional turntable. When the rotary transformer of the two-dimensional turntable detects the adjusted angle position, it feeds back the position information to the computer controller, which compares and compensates the data information obtained with the data information given by the CCD, and then re-controls the inner and outer ring motors to rotate, thereby completing the initial pointing to the target.

Claims

1. A method for realizing initial pointing of a movable ground laser communication terminal, characterized in that: The following steps are involved: S1, initialization; S2, 2D turntable zeroing; S3, after receiving the local position and posture data, the serial port is interrupted; S4, parsing local position and posture information; S5, calculating the pointing angle, and obtaining the outer ring angle and the inner ring angle that the two-dimensional turntable needs to rotate; S6, control the two-dimensional turntable to rotate to the corresponding pointing angle position according to the outer ring angle and inner ring angle that the two-dimensional turntable needs to rotate, and judge whether it is pointing to the target through the target light at the CCD spot position. If yes, the initial pointing of the target is completed. If not, continue to rotate the two-dimensional turntable according to the deviation position calculation result to complete the initial pointing of the target.

2. The method for realizing initial pointing of a mobile ground laser communication terminal according to claim 1, characterized in that: In S3, the global navigation system / inertial navigation system combination module corrects the drift caused by the inertial navigation system through the global navigation system. When the global navigation system fails to work, the inertial navigation system takes over the work of the global navigation system.

3. The method for realizing initial pointing of a mobile ground laser communication terminal according to claim 1, characterized in that: The specific steps of S4 are: obtaining the azimuth and elevation angles through the local position, attitude information, and target ephemeris.

4. The method for realizing initial pointing of a mobile ground laser communication terminal according to claim 1, characterized in that: The specific steps of S5 are: S501, angle translation, to obtain an azimuth angle Az' and an elevation angle El' after the angle translation; S502, according to S501, obtain the outer ring angle θ O and the inner ring angle θ I ; S503, perform horizontal correction on S502 to obtain the outer ring angle θ' after horizontal correction O and the horizontally corrected inner ring angle θ' I ; S504, perform zero position correction on S503 to obtain the outer ring angle θ that the two-dimensional turntable needs to rotate." O and the inner ring angle θ that the two-dimensional turntable needs to rotate I .

5. The method for realizing initial pointing of a mobile ground laser communication terminal according to claim 4, characterized in that: In S501, the specific formula for calculating the azimuth angle Az' after the angle translation and the elevation angle El' after the angle translation is: El'=El Among them, Az is the azimuth in the northeast sky coordinate system, El is the elevation angle in the northeast sky coordinate system, and α is the X GPS The angle with Xt, β is X GPS Angle with Yd, X GPS It is the vector direction from the main antenna to the auxiliary antenna in the GPS antenna coordinate system on the station, Xt is the reducer side pointing to the center of the outer frame in the vehicle station coordinate system, and Yd is due north in the northeast sky coordinate system.

6. The method for realizing initial pointing of a mobile ground laser communication terminal according to claim 4, characterized in that: In S502, the outer ring angle θ is calculated. O and the inner ring angle θ I The specific formula is: Among them, Az' is the azimuth after angle translation, El' is the pitch angle after angle translation, and x, y, and z are the three-dimensional coordinates of the vector between the satellite and the movable ground laser communication terminal.

7. The method for realizing initial pointing of a mobile ground laser communication terminal according to claim 4, characterized in that: In S503, the outer ring angle θ' after horizontal correction is calculated. O and the horizontally corrected inner ring angle θ' I The specific formula is: Among them, θ O is the outer ring angle, θ I is the inner ring angle, γ y is the angle of the Yt azimuth measured by the level instrument, γ x is the angle of the Xt azimuth measured by the level instrument, Xt is the reducer side pointing to the center of the outer frame in the vehicle-mounted station coordinate system, and Yt is the reducer motor side pointing to the center of the inner frame in the vehicle-mounted station coordinate system.

8. The method for realizing initial pointing of a mobile ground laser communication terminal according to claim 4, characterized in that: In S504, the outer ring angle θ that the two-dimensional turntable needs to rotate is calculated. O and the inner ring angle θ that the two-dimensional turntable needs to rotate I The specific formula is: in, is the code disk value of the outer ring in the terminal reference state, is the code disk value of the inner ring in the terminal reference state, θ' O is the outer ring angle after horizontal correction, θ' I is the inner ring angle after horizontal correction.

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