Periscopic laser communication terminal coarse tracking rotation angle adaptive control system and method
By introducing spot center of mass offset calculation and rotation angle increment calculation unit into the periscope laser communication terminal, the rotation angle of the azimuth axis and pitch axis is adaptively optimized, which solves the problem of difficult adjustment of the incident direction of the light wave and achieves more efficient rough tracking control.
Patent Information
- Application Number
- CN202510781830.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2025-08-15
AI Technical Summary
During the coarse tracking process, it is difficult for the existing periscope laser communication terminal to quickly solve the angle increment value of the azimuth axis and pitch axis incident in the direction perpendicular to the incident aperture plane of the periscope, and the rotation angle is not stable enough, and there is a problem of accumulation of rotation errors.
A periscopic laser communication terminal coarse tracking rotation angle adaptive control system is provided, including a spot center of mass offset calculation unit, a rotation angle increment calculation unit, a rotation control unit and a rotation actuator. By calculating the spot center of mass offset and rotation angle increment, the rotation angle of the azimuth axis and the pitch axis are adaptively optimized to realize the incident of the light wave along the plane perpendicular to the incident aperture.
It realizes fast and smooth adjustment of the incident direction of light waves, improves the coarse tracking response speed, avoids the accumulation of rotation errors, and provides higher tracking accuracy and stability.
Smart Images
Figure CN120498538A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of coarse tracking control of free space laser communication. Background Art
[0002] Compared to traditional radio communications, free-space laser communications offer higher transmission rates, lower power consumption, and greater confidentiality, and have received significant attention from academia and industry in recent years. Capture and tracking are key technologies in free-space laser communications. Capture refers to the use of beam scanning detection methods by both communicating parties to achieve preliminary positioning and alignment with each other before establishing a laser communication link. Tracking, after capture is achieved, involves real-time adjustment of the beam pointing to compensate for the relative motion of the laser communication terminal and platform vibration. Typically, a laser communication terminal includes two levels of tracking units: coarse tracking and fine tracking. The coarse tracking unit performs preliminary alignment in real time, while the fine tracking unit is responsible for achieving real-time, high-precision alignment.
[0003] In free-space laser communications, coarse tracking can be achieved using either a latitude-altitude coarse pointing system or a periscope-based coarse pointing system. Compared to latitude-altitude coarse pointing systems, periscope-based coarse pointing systems offer advantages such as reduced moment of inertia, lower motor control requirements, and easier temperature control. These systems are widely used in satellite laser communications. A paper published in Optics and Precision Engineering, Vol. 20, No. 2, 2012, pp. 270-276, describes a coarse tracking method for periscope-based laser communication terminals.
[0004] Figure 1 The figure shows the optical path structure of the periscope laser communication terminal optical system, where the base optical axis 101 overlaps with the line from the center of reflector A2 to the center of CCD3, the azimuth axis 102 overlaps with the line from the center of reflector B4 to the center of reflector A2, the pitch axis 103 overlaps with the line from the center of reflector C5 to the center of reflector B4, and the entrance pupil optical axis 104 is perpendicular to the incident aperture plane of the periscope 6 and passes through the center of the incident aperture; the telescope 7 is located between the reflector B4 and the reflector A2, and its center overlaps with the azimuth axis 102; the focusing lens 8 is located between the reflector A2 and CCD3, and its center overlaps with the base optical axis 101; the detection plane of CCD3 is perpendicular to the base optical axis 101, the entrance pupil optical axis 104 and the pitch axis 103 are mutually perpendicular, the azimuth axis 102 and the pitch axis 103 are mutually perpendicular, and the azimuth axis 102 and the base optical axis 101 are mutually perpendicular.
[0005] In order to solve the relationship between the centroid position of the light spot formed on CCD3 by the light wave entering the incident aperture of periscope 6 and the incident direction of the light wave, it is necessary to construct three right-handed coordinate systems, namely the x0-y0-z0 coordinate system (base coordinate system), the x1-y1-z1 coordinate system (azimuth coordinate system), and the x2-y2-z2 coordinate system (entrance pupil coordinate system). The x0 axis of the x0-y0-z0 coordinate system is along the direction from the center of reflector A2 to the center of CCD3, and the z0 axis of the x0-y0-z0 coordinate system is along the direction from the center of reflector A2 to the center of reflector B4. The x1 axis of the x1-y1-z1 coordinate system is along the direction from the center of reflector B4 to the center of reflector C5, and the z1 axis of the x1-y1-z1 coordinate system is along the direction from the center of reflector A2 to the center of reflector B4. The x2 axis of the x2-y2-z2 coordinate system is in the direction from the center of the reflector B4 to the center of the reflector C5, and the z2 axis of the x2-y2-z2 coordinate system is in the direction from the center of the incident aperture of the periscope 6 to the center of the reflector C5.
[0006] According to Section 3.5 of Mathematical Methods for Optical Sciences, published by Cambridge University Press in 2011, in the x2-y2-z2 coordinate system, the unit vector r2 in the incident direction of the light wave can be expressed as r2 = [sinθ2cosφ2, sinθ2sinφ2, cosθ2] T , where θ2 represents the polar angle of vector r2 in the x2-y2-z2 coordinate system relative to the positive direction of the z2 axis, φ2 represents the azimuth of vector r2 in the x2-y2-z2 coordinate system on the x2-y2 plane, and the superscript "T" represents the transpose. The matrix of the reflection of light by a plane mirror can be written as: T M =I-2n·n T , I represents the 3×3 unit matrix, n represents the unit normal vector of the plane mirror in three-dimensional space (a column vector, which can be regarded as a 3×1 matrix), and “·” represents matrix multiplication; let the unit vector of the incident light direction be L i , then the unit vector L of the direction of the reflected light of the plane mirror is r =T M L i , where L i and L r are column vectors.
[0007] Let T 21 Represents a transformation matrix that transforms a vector defined in the x2-y2-z2 coordinate system to the x1-y1-z1 coordinate system (depending on the current pitch axis angle θ EL ), T 10Represents a transformation matrix that transforms a vector defined in the x1-y1-z1 coordinate system to the x0-y0-z0 coordinate system (depending on the current azimuth axis angle θ AZ ), T TM represents the magnification matrix of the telescope 7 (depending on the magnification M of the telescope), then the direction of the light incident on the focusing lens 8 in front of the CCD 3 is r0=T MA T TM T MB T 10 T MC T 21 r2, where T MA Represents the effect matrix of reflector A2 on light reflection (the unit normal vector of reflector A is defined in the x0-y0-z0 coordinate system), T MB Represents the matrix of the effect of reflector B4 on the light reflection (depending on the current azimuth axis angle θ AZ , the unit normal vector of the reflector B is defined in the x0-y0-z0 coordinate system), T MC Represents the matrix of the effect of the reflector C5 on the light reflection (depending on the current pitch axis angle θ EL , the unit normal vector of the mirror C is defined in the x1-y1-z1 coordinate system).
[0008] When the center of mass of the light spot formed by the light wave incident on CCD3 is offset from the center of CCD in the x0-y0-z0 coordinate system by (δ y0 ,δ z0 ), the direction vector of the light incident on the focusing lens 8 in front of CCD3 can be expressed as r ccd =[1,δ y0 / f,δ z0 / f] T , f represents the focal length of the focusing lens, δ y0 represents the offset along the y0 axis, δ z0 Indicates the offset along the z0 axis. Let Normalize(r0)=Normalize(r ccd ), Normalize(x) means to perform normalization calculation on vector x. Solving the equations corresponding to the above equations can yield the result when δ is known. y0 , δ z0 ,θ AZ ,θ EL Under the conditions of , M, and f, the calculation expressions of θ2 and φ2, that is, when δ is measured y0 and δ z0After that, the unit vector r2 of the incident direction of the light wave can be calculated. The paper "NFIRE-to-TerraSAR-X Laser Communication Results: Satellite Pointing, Disturbances, and Other Attributes Consistent With Successful Performance" in the 2009 SPIE Conference Proceedings Volume 7330 also introduced a method for calculating the centroid position of the light spot formed on the CCD plane by the light wave entering the incident aperture of the periscope. The expression of the telescope's magnification matrix is given (see the matrix M in the paper). T ).
[0009] For a given periscope coarse pointing system (given the values of M and f), according to the measured δ y0 and δ z0 And the current azimuth axis angle θ AZ and the current pitch axis angle θ EL , θ2 and φ2 can be calculated, and then the value of vector r2 can be obtained. Then the vector r2 defined in the x2-y2-z2 coordinate system is transformed into the x0-y0-z0 coordinate system to obtain the vector r 2,0 =T 10 T 21 r2. Referring to Section 3.5 of Mathematical Methods for Optical Sciences, published by Cambridge University Press in 2011, the vector r can be calculated. 2,0 The corresponding polar angle β1 relative to the positive direction of the z0 axis in the x0-y0-z0 coordinate system, β1∈[0,π], can be calculated as the vector r 2,0 The azimuth angle α1 in the x0-y0 plane of the x0-y0-z0 coordinate system corresponds to α1, where α1∈[0,2π). Note that if β1 = 0 or π, α1 can take any value in the range [0,2π). To achieve coarse pointing alignment, the target angular position to which the azimuth axis must be rotated depends on α1, and the target angular position to which the elevation axis must be rotated depends on β1.
[0010] like Figure 2As shown, for any given light wave incident direction, there are two different sets of target azimuth and elevation angles, both of which enable the light wave to enter the periscope parallel to the entrance pupil axis (the two sets of elevation and entrance pupil axes are represented by thick solid and dashed lines, respectively). During coarse tracking, the optimal target values for the azimuth and elevation angles need to be adaptively determined based on the current azimuth and elevation angles, with the criterion of minimizing the angular rotation. This is the technical problem to be solved by the present invention. Summary of the Invention
[0011] In order to solve the technical problems in the coarse tracking of existing periscope laser communication terminals, namely, quickly solving two sets of azimuth axis rotation angles and pitch axis rotation angle increments that enable light waves to be incident in a direction perpendicular to the incident aperture plane of the periscope, and adaptively optimizing the selection of azimuth axis and pitch axis rotation angle increments based on the criterion of minimizing the rotation angle, the present invention provides a coarse tracking rotation angle adaptive control system and method for a periscope laser communication terminal.
[0012] The technical solution provided by the present invention is, on the one hand, a periscope laser communication terminal coarse tracking rotation angle adaptive control system, such as Figure 3 As shown, it includes a periscope laser communication terminal optical system, a light spot centroid offset calculation unit, a rotation angle increment calculation unit, a rotation control unit and a rotation actuator. The incident light wave reaches the detection plane of its CCD through the periscope laser communication terminal optical system, and the light spot image detected by the CCD is transmitted to the light spot centroid offset calculation unit. The two-dimensional position offset calculated by the light spot centroid offset calculation unit is transmitted to the rotation angle increment calculation unit. The rotation angle increment calculation unit can calculate the rotation angle increment of the azimuth axis and the pitch axis and transmit it to the rotation control unit. The rotation control unit can control the rotation actuator to rotate the azimuth axis and the pitch axis by a given rotation angle increment, thereby adjusting the incident direction of the incident light wave in the x2-y2-z2 coordinate system.
[0013] Another aspect of the technical solution provided by the present invention is a method for adaptively controlling the coarse tracking rotation angle of a periscope laser communication terminal, comprising the following steps:
[0014] S1, obtain the current azimuth axis rotation angle value and the current pitch axis rotation angle value of the periscope laser communication terminal, and convert the current azimuth axis rotation angle θ into the rotation angle increment calculation unit. AZ and the current pitch axis angle θ EL The values of the variables are assigned to the current azimuth axis angle value and the current pitch axis angle value obtained;
[0015] S2. The light spot image detected by CCD3 is transmitted to the light spot centroid offset calculation unit, which calculates the two-dimensional position offset of the light spot centroid relative to the center of CCD3 in the x0-y0-z0 coordinate system;
[0016] S3, the rotation angle increment calculation unit receives the two-dimensional position offset obtained in S2 and calculates the vector r 2,0 , vector r 2,0 The corresponding polar angle β1 relative to the positive direction of the z0 axis in the x0-y0-z0 coordinate system, β1∈[0,π], and the vector r 2,0 The azimuth angle α1 on the x0-y0 plane corresponding to the x0-y0-z0 coordinate system, α1∈[0,2π), if β1=0 or π, α1 can take any value in the range [0,2π); define γ1=π-β1;
[0017] S4. The rotation angle increment calculation unit calculates two sets of azimuth axis and elevation axis rotation angle increment values so that the incident light wave can be incident in a direction perpendicular to the incident aperture plane of the periscope, and transmits the adaptive optimal rotation angle increment value to the rotation control unit;
[0018] S5. The rotation control unit controls the rotation actuator to rotate the corresponding azimuth axis and pitch axis angle increment values. If no instruction to end the coarse tracking operation is received, go to S1, otherwise the coarse tracking of the periscope laser communication terminal is ended.
[0019] Furthermore, the calculation of the two sets of azimuth axis and pitch axis angle increment values in S4 is specifically as follows:
[0020] The first group: If the current pitch axis angle θ EL >0, then let α0=θ AZ +π / 2, otherwise let α0=θ AZ -π / 2; let Where [x] means taking the integer part of x,
[0021]
[0022] If the current pitch axis angle θ EL >0, then let β t =γ1, otherwise let β t =-γ1, pitch axis angle increment β d =β t -θ EL ;
[0023] The second group: If the current pitch axis angle θ EL >0, then let Otherwise, make Where [x] means taking the integer part of x,
[0024]
[0025] If the current pitch axis angle θ EL>0, then let Otherwise, Pitch axis angle increment
[0026] Furthermore, two sets of azimuth axis and pitch axis rotation angle increment values are calculated in S4, and the preferred rotation angle increment values are specifically:
[0027] Let T max,1 =max(|α d |,|β d |), Where max(x,y) means taking the maximum value of x and y; if T max,1 >T max,2 , then let Otherwise, let Δ π =α d , Δ EL =β d ; Δ AZ and Δ EL They represent the optimized azimuth and pitch axis angle increments respectively.
[0028] Technical effects:
[0029] The present invention overcomes the multi-solution problem of complex trigonometric equations, rapidly calculating in real time the two sets of azimuth and elevation angle increments required to ensure that light waves are incident perpendicular to the periscope's incident aperture plane. The optimal azimuth and elevation angle increments are adaptively selected based on the principle of minimizing the rotation angle, thereby ensuring smoother angular rotation of the rotary actuator during coarse tracking and providing a higher coarse tracking response speed. Furthermore, the present invention reacquires the current azimuth and elevation angle values of the periscope laser communication terminal at each discrete control processing time step, thereby avoiding the problem of cumulative rotation errors in the rotary actuator. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 Schematic diagram of the optical path structure of the periscope laser communication terminal optical system.
[0031] Figure 2 Schematic diagram of two different sets of target values for the azimuth and elevation axis rotation angles to ensure that light waves can enter the periscope in a direction perpendicular to the periscope's incident aperture plane.
[0032] Figure 3 This is a schematic diagram of the structure of the coarse tracking rotation angle adaptive control system for a periscope laser communication terminal.
[0033] Figure 4 This is the overall block diagram of the coarse tracking rotation angle adaptive control method for periscope laser communication terminal.
[0034] Among them, 101, base optical axis, 102, azimuth axis, 103, pitch axis, 104, entrance pupil optical axis, 2, reflector A, 3, CCD, 4, reflector B, 5, reflector C, 6, periscope, 7, telescope, 8, focusing lens. DETAILED DESCRIPTION
[0035] To make the features and advantages of the coarse tracking rotation angle adaptive control system and method for a periscope laser communication terminal more clearly understood, the present invention is further described below in conjunction with specific embodiments. Obviously, the described embodiments are only a portion of the embodiments of the present invention, not all of them.
[0036] On the one hand, this embodiment provides a periscope laser communication terminal coarse tracking rotation angle adaptive control system, such as Figure 3 As shown, it includes a periscope laser communication terminal optical system, a light spot centroid offset calculation unit, a rotation angle increment calculation unit, a rotation control unit and a rotation actuator. The incident light wave reaches the detection plane of its CCD3 through the periscope laser communication terminal optical system. The light spot image detected by CCD3 is transmitted to the light spot centroid offset calculation unit. The two-dimensional position offset calculated by the light spot centroid offset calculation unit is transmitted to the rotation angle increment calculation unit. The rotation angle increment calculation unit can calculate the rotation angle increment of the azimuth axis and the pitch axis and transmit it to the rotation control unit. The rotation control unit can control the rotation actuator to rotate the azimuth axis and the pitch axis by a given rotation angle increment, thereby adjusting the incident direction of the incident light wave in the x2-y2-z2 coordinate system.
[0037] The periscope laser communication terminal optical system, such as Figure 1 As shown, the incident light wave enters the periscope 6 from the incident aperture on the incident aperture plane of the periscope 6, is reflected by the reflector C5 and reaches the reflector B4, is further reflected by the reflector B4, passes through the telescope 7 and reaches the reflector A2, and is then reflected by the reflector A2 and reaches the focusing lens 8. The focusing lens 8 focuses the light wave onto the detection plane of the CCD 3. Rotating the azimuth axis 102 can cause the pitch axis 103, the reflector C5, the incident aperture of the periscope 6, and the entrance pupil optical axis 104 to rotate about the azimuth axis 102, while changing the direction of the normal vector of the reflector B4; rotating the pitch axis 103 can cause the incident aperture of the periscope 6 and the entrance pupil optical axis 104 to rotate about the pitch axis 103, while changing the direction of the normal vector of the reflector C5.
[0038] In this embodiment, the reflector A2, the reflector B4, and the reflector C5 are all 45° plane mirrors.
[0039] In this embodiment, the rotation control unit can be specifically designed and implemented with reference to the method described in the paper Journal of Changchun University of Science and Technology (Natural Science Edition), Vol. 42, No. 6, pp. 7-14, 2019. Figure 3 The arrow from the rotary actuator to the rotary control unit indicates the direction of feedback signal transmission required for three-loop control.
[0040] Under the initial condition, the base optical axis 101 is parallel to the pitch axis 103, the azimuth axis 102 is parallel to the entrance pupil optical axis 104, and the azimuth axis rotation angle θ AZ =0rad, pitch axis angle θ EL = 0rad. Note: When observing with the positive z0 axis pointing to the eye, counterclockwise rotation of the azimuth axis represents a positive angle, and clockwise rotation of the azimuth axis represents a negative angle. When observing with the positive x1 axis pointing to the eye, counterclockwise rotation of the pitch axis represents a positive angle, and clockwise rotation of the pitch axis represents a negative angle.
[0041] On the other hand, this embodiment introduces in detail a method for adaptive control of the coarse tracking rotation angle of a periscope laser communication terminal.
[0042] First, the periscope laser communication terminal performs a laser beam capture operation so that the light waves sent by the other communication terminal can enter the periscope laser communication terminal and reach the detection plane of CCD3 therein. The periscope laser communication terminal performs a coarse tracking operation. The specific steps are as follows:
[0043] In the program of the rotation angle increment calculation unit, the time variable t is set to 0.
[0044] like Figure 4 As shown, S1, obtain the current azimuth axis rotation angle value and the current pitch axis rotation angle value of the periscope laser communication terminal through the sensor, and convert the current azimuth axis rotation angle θ into the rotation angle increment calculation unit. AZ and the current pitch axis angle θ EL The values of the variables are assigned to the current azimuth axis angle value and the current pitch axis angle value obtained;
[0045] S2, transmit the spot image detected by CCD at time t to the spot centroid offset calculation unit, and calculate the two-dimensional position offset (δ y0 ,δ z0 ), put (δ y0 ,δ z0 ) is transmitted to the rotation angle increment calculation unit.
[0046] S3, first, the rotation angle increment calculation unit calculates the rotation angle increment according to δ y0 , δ z0 ,θAZ ,θ EL , M, f values, calculated as Figure 2 The incident direction of the light wave shown is the unit vector r2 in the x2-y2-z2 coordinate system, where M represents the magnification of the telescope 7 and f represents the focal length of the focusing lens 8.
[0047] Then the rotation angle increment calculation unit calculates r 2,0 =T 10 T 21 r2:
[0048] Among them, r 2,0 It represents the result of transforming the vector r2 defined in the x2-y2-z2 coordinate system to the x0-y0-z0 coordinate system. 21 Represents the transformation matrix that transforms a vector defined in the x2-y2-z2 coordinate system to the x1-y1-z1 coordinate system, T 10 It represents the transformation matrix that transforms a vector defined in the x1-y1-z1 coordinate system to the x0-y0-z0 coordinate system. The book Computer Graphics: Principles and Practice (3rd Edition) published by Addison-Wesley in 2014 introduces the method of solving the transformation matrix that transforms a vector defined in one three-dimensional coordinate system to another three-dimensional coordinate system, which can be used to solve T 21 and T 10 .
[0049] Then calculate the vector r 2,0 The corresponding polar angle β1 relative to the positive direction of the z0 axis in the x0-y0-z0 coordinate system is β1∈[0,π],
[0050] Calculate vector r 2,0 The azimuth angle α1 on the x0-y0 plane corresponding to the x0-y0-z0 coordinate system, α1∈[0,2π), if β1=0 or π, α1 can take any value in the range [0,2π);
[0051] In order to achieve coarse pointing alignment, the target angle position to which the azimuth axis needs to be rotated depends on α1, and the target angle position to which the pitch axis needs to be rotated depends on β1;
[0052] Define γ1=π-β1.
[0053] like Figure 2 As shown, there are two different sets of azimuth axis angle and pitch axis angle target values. The first set (pitch axis and entrance pupil axis shown by the thick dashed line) azimuth axis angle target value and the pitch axis angle target value ψ0, the second group (pitch axis and entrance pupil axis shown by thick solid lines) azimuth axis angle target value The target value of the azimuth axis rotation and the pitch axis rotation target value -ψ0 can both make the light wave enter the periscope in a direction parallel to the entrance pupil optical axis. The two sets of target values correspond to different azimuth axis rotation and pitch axis rotation increment values, which are calculated by S4.
[0054] S4. The rotation angle increment calculation unit calculates two sets of azimuth axis and elevation axis rotation angle increment values so that the light wave sent by the other communication terminal can be incident along a direction perpendicular to the incident aperture plane of the periscope. The specific calculation steps are as follows:
[0055] Group 1:
[0056] If the current pitch axis angle θ EL >0, then let α0=θ AZ +π / 2, otherwise let α0=θ AZ -π / 2; let α d,0 =α1- Where [x] means taking the integer part of x (i.e. discarding the decimal part),
[0057]
[0058] Among them, α d In order to make the current light wave incident in the direction perpendicular to the incident aperture plane of the periscope under the condition that the positive and negative angle of the pitch axis remains unchanged, the azimuth axis needs to be rotated at the current azimuth axis angle θ AZ The angle of further rotation based on this.
[0059] If the current pitch axis angle β EL >0, then let β t =γ1, otherwise let β t =-γ1, pitch axis angle increment β d =β t -θ EL ;
[0060] Among them, β d In order to make the current light wave incident in the direction perpendicular to the incident aperture plane of the periscope under the condition that the positive and negative angle of the pitch axis remains unchanged, the pitch axis needs to be rotated at the current pitch axis angle θ EL The angle of further rotation based on this.
[0061] Group 2:
[0062] If the current pitch axis angle θ EL >0, then let Otherwise, make Where [x] means taking the integer part of x (i.e. discarding the decimal part),
[0063]
[0064] in, In order to make the current light wave incident in the direction perpendicular to the incident aperture plane of the periscope under the condition that the positive and negative angle of the pitch axis will change, the azimuth axis needs to be rotated at the current azimuth axis angle θ AZ The angle of further rotation based on this.
[0065] If the current pitch axis angle θ EL >0, then let Otherwise, Pitch axis angle increment θ EL ;
[0066] in, In order to make the current light wave incident in the direction perpendicular to the incident aperture plane of the periscope under the condition that the positive and negative of the pitch axis angle will change, the pitch axis needs to be rotated at the current pitch axis angle θ EL The angle of further rotation based on this.
[0067] The specific steps for adaptively optimizing the azimuth and pitch axis angle increments are as follows:
[0068] make Where max(x,y) means taking the maximum value of x and y. In order to make the current light wave incident along the direction perpendicular to the incident aperture plane of the periscope, if T max,1 >T max,2 , then the azimuth axis needs to rotate at the current azimuth axis angle θ AZ Further rotation angle based on The pitch axis needs to be at the current pitch axis angle θ EL Further rotation angle based on Right now Otherwise the azimuth axis needs to rotate at the current azimuth axis angle θ AZ Further rotate angle α based on d , the pitch axis needs to be at the current pitch axis angle θ EL Further rotate angle β d , that is, Δ AZ =α d , Δ EL =β d , Δ AZ and Δ EL They represent the optimized azimuth and pitch axis angle increments respectively.
[0069] S5, the azimuth axis of the rotary actuator is further rotated by an angle Δ based on the current state by the rotation control unit. AZ , controls the pitch axis of the rotary actuator to further rotate the angle Δ based on the current state EL ; In the program of the rotation angle increment calculation unit, let t = t + Δ t , Δ t represents the discrete control processing time step of the coarse tracking rotation angle adaptive control system of the periscope laser communication terminal. In this embodiment, Δ t =10ms.
[0070] If no instruction to end the coarse tracking operation is received, go to S1, otherwise the coarse tracking of the periscope laser communication terminal is ended.
[0071] Under the initial conditions, the unit normal vector of the reflector A2 is expressed in the base coordinate system as The unit normal vector of the reflector B4 is expressed in the base coordinate system as The unit normal vector of the reflector C5 is expressed in the azimuth coordinate system as Chapter 4 of the book "Mathematics for 3D Game Programming and Computer Graphics" published by Course Technology Press in 2012 introduces the calculation methods for performing various rotation transformation operations on vectors. This method can be used to calculate the changes in the unit normal vectors of mirrors B4 and C5 caused by the rotation of the azimuth and pitch axes, and then calculate the rotation angle θ of different azimuth axes. AZ and pitch axis angle θ EL The effect matrix of reflector B4 and reflector C5 on light reflection under the following conditions.
[0072] It is worth pointing out that the units of all the angles mentioned above are radians (rad).
[0073] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.
Claims
1. The coarse tracking rotation angle adaptive control system of the periscope laser communication terminal is characterized by: The invention comprises a periscope laser communication terminal optical system, a light spot centroid offset calculation unit, a rotation angle increment calculation unit, a rotation control unit and a rotation actuator. An incident light wave reaches a detection plane of a CCD (3) of the periscope laser communication terminal optical system through the periscope laser communication terminal optical system. The light spot image detected by the CCD (3) is transmitted to the light spot centroid offset calculation unit. The two-dimensional position offset calculated by the light spot centroid offset calculation unit is transmitted to the rotation angle increment calculation unit. The rotation angle increment calculation unit can calculate the rotation angle increment of the azimuth axis and the pitch axis and transmit it to the rotation control unit. The rotation control unit can control the rotation actuator so that the azimuth axis and the pitch axis rotate by a given rotation angle increment, thereby adjusting the incident direction of the incident light wave in the x2-y2-z2 coordinate system.
2. The control method of the periscope laser communication terminal coarse tracking rotation angle adaptive control system according to claim 1 is characterized in that: The steps include: S1, obtain the current azimuth axis rotation angle value and the current pitch axis rotation angle value of the periscope laser communication terminal, and convert the current azimuth axis rotation angle θ into the rotation angle increment calculation unit. AZ and the current pitch axis angle θ EL The values of the variables are assigned to the current azimuth axis angle value and the current pitch axis angle value obtained; S2, transmitting the light spot image detected by the CCD (3) to the light spot centroid offset calculation unit, which calculates the two-dimensional position offset of the light spot centroid relative to the center of the CCD (3) in the x0-y0-z0 coordinate system; S3, the rotation angle increment calculation unit receives the two-dimensional position offset obtained in S2 and calculates the vector r 2,0 , vector r 2,0 The corresponding polar angle β1 relative to the positive direction of the z0 axis in the x0-y0-z0 coordinate system, β1∈[0,π], and the vector r 2,0 The azimuth angle α1 on the x0-y0 plane corresponding to the x0-y0-z0 coordinate system, α1∈[0,2π), if β1=0 or π, α1 takes any value in the range [0,2π); define γ1=π-β1; S4. The rotation angle increment calculation unit calculates two sets of azimuth axis and elevation axis rotation angle increment values so that the incident light wave can be incident in a direction perpendicular to the incident aperture plane of the periscope, and transmits the adaptive optimal rotation angle increment value to the rotation control unit; S5. The rotation control unit controls the rotation actuator to rotate the corresponding azimuth axis and pitch axis angle increment values. If no instruction to end the coarse tracking operation is received, go to S1, otherwise the coarse tracking of the periscope laser communication terminal is ended.
3. The coarse tracking rotation angle adaptive control method of a periscope laser communication terminal according to claim 2, characterized in that: The calculation of the two sets of azimuth axis and pitch axis angle increment values in S4 is specifically as follows: The first group: If the current pitch axis angle θ EL >0, then let α0=θ AZ +π / 2, otherwise let α0=θ AZ -π / 2; let Where [x] means taking the integer part of x, If the current pitch axis angle θ EL >0, then let β t =γ1, otherwise let β t =-γ1, pitch axis angle increment β d =β t -θ EL ; The second group: If the current pitch axis angle θ EL >0, then let Otherwise, make Where [x] means taking the integer part of x, If the current pitch axis angle θ EL >0, then let Otherwise, Pitch axis angle increment 4. The periscope laser communication terminal coarse tracking rotation angle adaptive control method according to claim 3 is characterized in that: In S4, two sets of azimuth axis and pitch axis rotation angle increment values are calculated. The preferred rotation angle increment values are: Let T max,1 =max(|α d |,|β d |), Where max(x,y) means taking the maximum value of x and y; if T max,1 >T max,2 , then let Otherwise, let Δ AZ =α d , Δ EL =β d ; Δ AZ and Δ EL They represent the optimized azimuth and pitch axis angle increments respectively.
5. The periscope laser communication terminal coarse tracking rotation angle adaptive control method according to claim 4 is characterized in that: In the step S5, the rotation control unit controls the azimuth axis of the rotary actuator to further rotate the angle Δ based on the current state. AZ , controls the pitch axis of the rotary actuator to further rotate the angle Δ based on the current state EL ; In the program of the rotation angle increment calculation unit, let t = t + Δ t , Δ t Represents the discrete control processing time step of the coarse tracking rotation angle adaptive control system of the periscope laser communication terminal.