Coarse and fine integrated pointing mechanism for optical communication

Abstract

This invention relates to an integrated coarse and fine pointing mechanism for optical communication, belonging to the field of optical communication equipment. It primarily addresses the problems of bulky size and low collaborative efficiency caused by separate coarse and fine pointing mechanisms in existing technologies. The key technical points are: integrating coarse and fine pointing functions into a single compact structure; achieving large-range coarse adjustment around the azimuth axis y1 via a turntable on the base; and achieving high-precision fine adjustment around the pitch axis x2 and azimuth axis y2 via a reflector support frame and reflector on the mounting component; driven by first, second, and third motors respectively; and achieving full-state sensing through multi-axis angle sensors, beam position detectors, and a temperature monitoring module; the controller performs real-time thermal error feedforward compensation on the drive commands of the fine pointing motor based on temperature monitoring data and a pre-stored thermal deformation compensation model. This mechanism is mainly used in free-space optical communication systems to achieve rapid beam acquisition, high-precision alignment, and stable tracking.

Description

Technical Field

[0001] This invention relates to the field of optical communication equipment. More specifically, this invention relates to a coarse-precision integrated pointing mechanism for optical communication. Background Technology

[0002] Traditional optical communication pointing mechanisms include two types: a coarse pointing mechanism and a fine pointing mechanism. The coarse pointing mechanism is responsible for large-angle rotation (0° to 360°) to capture the target beam; while the fine pointing mechanism is responsible for high-precision rotation to finely adjust the beam direction, improving system pointing accuracy and bandwidth, ultimately achieving precise beam transmission to the target direction. Of these two pointing mechanisms, the coarse pointing mechanism is a crucial component of the optical communication terminal, and commonly used coarse pointing mechanisms include the tilting mirror type, the theodolite type, and the periscope type.

[0003] Traditional coarse pointing mechanisms have relatively simple functions and low precision, and require strict perpendicularity between the azimuth and pitch axes, placing high demands on machining accuracy. Fine pointing mechanisms, on the other hand, have relatively limited rotation angles of the reflector around the azimuth and pitch axes. In practical use, both types of pointing mechanisms not only occupy a large space and are expensive, but their efficiency in coordinating to capture the target beam and project it in the set direction is also low. Summary of the Invention

[0004] One object of the present invention is to solve at least the above-mentioned problems and to provide a coarse and fine integrated pointing mechanism for optical communication.

[0005] To achieve these objectives and other advantages according to the present invention, a coarse-fine integrated pointing mechanism for optical communication is provided, comprising:

[0006] A base has a turntable rotatably mounted on its top. The turntable's rotation axis is vertical and is the azimuth axis y1. A cross-shaped mounting component is fixedly connected to the top of the turntable. A reflector support frame is rotatably mounted between the two ends of the mounting component in the same direction. The reflector support frame's rotation axis is horizontal and is the pitch axis x2. A reflector is rotatably mounted on the reflector support frame. The reflector's mirror surface faces outward. The reflector's rotation axis is horizontal and is the azimuth axis y2, which is perpendicular to the pitch axis x2.

[0007] The drive assembly includes a first motor for driving the turntable to rotate, a second motor for driving the reflector support frame to rotate, and a third motor for driving the reflector to rotate.

[0008] The detection component includes a first angle sensor for detecting the rotation angle of the azimuth axis y1, a second angle sensor for detecting the rotation angle of the pitch axis x2, a third angle sensor for detecting the rotation angle of the azimuth axis y2, a beam position detector, and a temperature monitoring module. The beam position detector is located in the receiving optical path of the beam after reflection by the reflector and is used to detect the position deviation of the beam. The temperature monitoring module is used to monitor the temperature of the first motor, the second motor, and the reflector support frame.

[0009] The controller is connected to the first motor, the second motor, the third motor, the first angle sensor, the second angle sensor, the third angle sensor, the beam position detector, and the temperature monitoring module. The controller has a pre-stored thermal deformation compensation model. Based on the monitoring data of the temperature monitoring module and the thermal deformation compensation model, the controller performs real-time thermal error compensation on the drive commands of the second motor and the third motor.

[0010] Preferably, the controller executes the following control flow:

[0011] S1. The controller starts the first motor, driving the turntable to rotate around the azimuth axis y1 until the beam position detector detects the target beam and stops the first motor.

[0012] S2. The controller receives the horizontal and vertical deviation signals of the beam generated by the beam position detector. Based on the horizontal deviation signal, it generates a third motor drive command and sends it to the third motor. The third motor drives the reflector to rotate around the azimuth axis y2 to eliminate the horizontal deviation.

[0013] S3. The controller generates a second motor drive command based on the vertical deviation signal and sends it to the second motor. The second motor drives the reflector support frame to rotate around the pitch axis x2 to eliminate the vertical deviation.

[0014] S4. When the beam position detector detects that both the horizontal and vertical deviations are less than the set thresholds, the controller locks the second and third motors.

[0015] Preferably, the temperature monitoring module includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The first temperature sensor is installed on the stator housing of the first motor, the second temperature sensor is installed on the stator housing of the second motor, and the third temperature sensor is installed on the reflector support frame.

[0016] The steps for constructing the thermal deformation compensation model for monitoring are as follows:

[0017] A1. Under constant reference temperature conditions, determine the initial alignment position of the reflector as the zero position, and simultaneously record the temperature values ​​indicated by the first temperature sensor, the second temperature sensor, and the third temperature sensor at this time as the reference temperature of each sensor.

[0018] A2. By controlling the first motor and / or the second motor to operate under different working conditions, or by combining external temperature control methods, the mechanism can generate different temperature distribution states; under each stable temperature state, the current temperature value of each temperature sensor is read synchronously, and the current actual angle deviation value of the reflector relative to the zero position is obtained by actual measurement using measuring instruments.

[0019] A3. Process the multiple sets of temperature values ​​and actual angle deviation values ​​collected synchronously in step A2 to determine the quantitative mapping relationship between the temperature change at each monitoring point and the angle deviation of the reflector, and define the mapping relationship as the thermal deformation compensation model.

[0020] The control process for real-time thermal error compensation by the controller is as follows:

[0021] B1. The controller periodically collects real-time temperature data from the first temperature sensor, the second temperature sensor, and the third temperature sensor;

[0022] B2. The controller calls the thermal deformation compensation model and calculates the predicted values ​​of thermally induced pitch angle deviation Δx and azimuth angle deviation Δy based on the real-time temperature data and the reference temperature value.

[0023] B3. The controller uses -Δx and -Δy as feedforward compensation values ​​to generate corresponding compensation instructions, which are then superimposed on the drive instructions sent to the second motor and the third motor.

[0024] Preferably, the bottom of the mounting component has multiple mounting holes circumferentially provided, and the upper surface of the turntable has threaded holes at positions corresponding to the mounting holes;

[0025] The mounting component is connected to the turntable via multiple isolation connection assemblies, each corresponding to a specific mounting hole. Each isolation connection assembly includes a bolt and an elastic damping element. The elastic damping element is press-fitted into the mounting hole and has a through hole at its center for the bolt to pass through. The bolt passes sequentially through the through hole of the elastic damping element and a washer located below the mounting hole, and finally screws into the threaded hole of the turntable. The shank of the bolt does not contact the inner wall of the mounting hole or the inner wall of the through hole of the elastic damping element.

[0026] The bottom of the turntable is coaxially provided with a first mounting end, and the rotor of the first motor is connected to the first mounting end through a flexible coupling.

[0027] The controller executes the following control flow: In step S1, when the beam position detector detects the target beam for the first time, the controller controls the first motor to decelerate at a first deceleration. After the rotation speed drops to a set value, it stops smoothly at a second deceleration lower than the first deceleration to suppress the stopping impact of the turntable. After completing step S1 and the first motor stops, a preset delay time is waited for the residual vibration of the turntable to be attenuated by the elastic damping element before executing steps S2 and S3.

[0028] Preferably, the reflector support frame is provided with a pair of second mounting ends, which are respectively rotatably located at both ends of the mounting component in the same direction by a pair of first precision bearings with high axial and radial rigidity;

[0029] The second motor is a frameless torque motor. The rotor of the second motor is fixedly mounted on one of the second mounting ends and located within the support span formed by a pair of first precision bearings. The stator of the second motor is fixedly mounted on the mounting component so that the stator of the second motor directly drives the rotor of the second motor, thereby driving the reflector support frame to rotate around the pitch axis x2.

[0030] The reflector is provided with a pair of third mounting ends, which are coaxial and connected by a line passing through the center of the reflector. The pair of third mounting ends are rotatably mounted on the reflector support frame by a pair of second precision bearings.

[0031] Preferably, it also includes:

[0032] The first limit switch is set at the extreme position of the rotation path of the reflector support frame;

[0033] The second limit switch is set at the extreme position of the rotation path of the reflector;

[0034] The normally closed contacts of the first and second limit switches are connected in series to the drive power circuits of the second and third motors. When any limit switch is triggered, the drive power of the corresponding motor is physically cut off.

[0035] Preferably, it also includes a main conductive slip ring, wherein the rotor end of the main conductive slip ring is coaxially fixed to the turntable and rotates with it, and the stator end is fixed to the base. The power supply and signal transmission cables of the second motor, the third motor, the first angle sensor, the second angle sensor, the third angle sensor and the beam position detector are connected to the external controller and power supply via the main conductive slip ring.

[0036] At least one third mounting end of the reflector is a hollow shaft structure, and a miniature conductive slip ring is coaxially disposed inside the hollow shaft structure; the rotor of the miniature conductive slip ring is fixedly connected to the third mounting end and rotates with the reflector, and the stator is fixedly connected to the reflector support frame; the power supply and signal transmission cables of the third motor and the third angle sensor are connected to the rotor end of the main conductive slip ring via the miniature conductive slip ring.

[0037] Preferably, it also includes an acceleration sensor, which is disposed on the reflector or the reflector support frame, for detecting the high-frequency vibration signal, and the acceleration sensor is communicatively connected to the controller;

[0038] The controller also has a pre-stored disturbance propagation model, which was obtained through experimental identification. This disturbance propagation model describes the dynamic relationship between the acceleration sensor signal and the angle disturbance of the reflector. The controller also executes the following control flow:

[0039] C1. The controller acquires the vibration signal detected by the acceleration sensor in real time;

[0040] C2. The controller, based on the disturbance transmission model, calculates the predicted mirror angle disturbance component in real time from the vibration signal;

[0041] C3. The controller uses the inverse vector of the predicted disturbance component as a feedforward compensation command, and fuses it with the fine tracking command based on the beam position detector and the thermal error compensation command based on the thermal deformation compensation model to jointly drive the second motor and the third motor.

[0042] The present invention has at least the following beneficial effects:

[0043] This invention integrates a coarse pointing mechanism and a fine pointing mechanism, providing an integrated coarse and fine pointing mechanism for optical communication. This mechanism simultaneously possesses wide-range acquisition and high-precision pointing capabilities. The coarse pointing mechanism captures the light beam by rotating at a large angle, while the fine pointing mechanism can precisely adjust the beam direction by rotating at a certain angle, ultimately sending the beam to the designated direction. The integrated coarse and fine pointing mechanism has a smaller footprint, smaller overall size, and lower cost, and since both share a single control system, it improves operational efficiency.

[0044] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0045] Figure 1 This is a front view of the coarse and fine integrated pointing mechanism for optical communication according to one of the technical solutions of the present invention;

[0046] Figure 2 This is a front view of the structure of the protective cover with a reflector as described in one of the technical solutions of the present invention.

[0047] Reference numerals in the attached drawings: 1-Base; 2-Turntable; 3-Mounting component; 301-Vertical plate; 302-Top plate; 4-Reflector support frame; 5-Reflector; 6-First mounting end; 7-Second mounting end; 8-Third mounting end; 9-First motor; 10-Second motor; 11-Third motor; 12-Bolt; 13-Washer; 14-Protective cover. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0049] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0050] like Figure 1-2 As shown, the present invention provides a coarse and fine integrated pointing mechanism for optical communication, comprising:

[0051] A base has a turntable rotatably mounted on its top. The turntable's rotation axis is vertical and is the azimuth axis y1. A cross-shaped mounting component is fixedly connected to the top of the turntable. A reflector support frame is rotatably mounted between the two ends of the mounting component in the same direction. The reflector support frame's rotation axis is horizontal and is the pitch axis x2. A reflector is rotatably mounted on the reflector support frame. The reflector's mirror surface faces outward. The reflector's rotation axis is horizontal and is the azimuth axis y2, which is perpendicular to the pitch axis x2.

[0052] The drive assembly includes a first motor for driving the turntable to rotate, a second motor for driving the reflector support frame to rotate, and a third motor for driving the reflector to rotate.

[0053] The detection assembly includes a first angle sensor for detecting the rotation angle of the azimuth axis y1, a second angle sensor for detecting the rotation angle of the pitch axis x2, a third angle sensor for detecting the rotation angle of the azimuth axis y2, a beam position detector, and a temperature monitoring module. The beam position detector is used to detect the position deviation of the beam, and the temperature monitoring module is used to monitor the temperature of the first motor, the second motor, and the reflector support frame.

[0054] The controller is connected to the first motor, the second motor, the third motor, the first angle sensor, the second angle sensor, the third angle sensor, the beam position detector, and the temperature monitoring module. The controller has a pre-stored thermal deformation compensation model. Based on the monitoring data of the temperature monitoring module and the thermal deformation compensation model, the controller performs real-time thermal error compensation on the drive commands of the second motor and the third motor.

[0055] The controller executes the following master alignment control flow:

[0056] S1. The controller starts the first motor, driving the turntable to rotate around the azimuth axis y1 until the beam position detector detects the target beam and stops the first motor.

[0057] S2. The controller receives the horizontal and vertical deviation signals of the beam generated by the beam position detector. Based on the horizontal deviation signal, it generates a third motor drive command and sends it to the third motor. The third motor drives the reflector to rotate around the azimuth axis y2 to eliminate the horizontal deviation.

[0058] S3. The controller generates a second motor drive command based on the vertical deviation signal and sends it to the second motor. The second motor drives the reflector support frame to rotate around the pitch axis x2 to eliminate the vertical deviation.

[0059] S4. When the beam position detector detects that both the horizontal and vertical deviations are less than the set thresholds, the controller locks the second and third motors.

[0060] The temperature monitoring module includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The first temperature sensor is installed on the stator housing of the first motor, the second temperature sensor is installed on the stator housing of the second motor, and the third temperature sensor is installed on the reflector support frame.

[0061] The steps for constructing the thermal deformation compensation model are as follows:

[0062] A1. Under constant reference temperature conditions, determine the initial alignment position of the reflector as the zero position, and simultaneously record the temperature values ​​indicated by the first temperature sensor, the second temperature sensor, and the third temperature sensor at this time as the reference temperature of each sensor.

[0063] A2. By controlling the first motor and / or the second motor to operate under different working conditions, or by combining external temperature control methods, the mechanism can generate different temperature distribution states; under each stable temperature state, the current temperature value of each temperature sensor is read synchronously, and the current actual angle deviation value of the reflector relative to the zero position is obtained by actual measurement using measuring instruments.

[0064] A3. Process the multiple sets of temperature values ​​and actual angle deviation values ​​collected synchronously in step A2 to determine the quantitative mapping relationship between the temperature change at each monitoring point and the angle deviation of the reflector, and define the mapping relationship as the thermal deformation compensation model.

[0065] The control process for real-time thermal error compensation by the controller is as follows:

[0066] B1. The controller periodically collects real-time temperature data from the first temperature sensor, the second temperature sensor, and the third temperature sensor;

[0067] B2. The controller calls the thermal deformation compensation model and calculates the predicted values ​​of thermally induced pitch angle deviation Δx and azimuth angle deviation Δy based on the real-time temperature data and the reference temperature value.

[0068] B3. The controller uses -Δx and -Δy as feedforward compensation values ​​to generate corresponding compensation instructions, which are then superimposed on the drive instructions sent to the second motor and the third motor.

[0069] In the above technical solution, the base 1 of the coarse and fine integrated pointing mechanism for optical communication can be made of aluminum alloy. The bottom of the turntable 2 is coaxially provided with a first mounting end 6, which can be a journal with a diameter of 50mm, and can be rotatably connected to the base 1 through an angular contact ball bearing. The rotation axis of the turntable 2 is vertical when it rotates, and this vertical rotation axis is defined as the azimuth axis y1.

[0070] Mounting component 3 has a U-shaped structure and can be made of aluminum alloy or stainless steel, preferably aluminum alloy. Mounting component 3 straddles the turntable 2 and is fixedly connected to the top of the turntable 2 by bolts so that it rotates with the turntable 2. The reflector support frame 4 can be a cylindrical groove structure or a circular plate structure, preferably a circular plate structure. The reflector support frame 4 can be made of aluminum alloy. The reflector support frame 4 is rotatably mounted between the two ends of the mounting component 3 in the same direction. Specifically, the reflector support frame 4 has a pair of second mounting ends 7. The second mounting ends 7 can be journals made of stainless steel. The two second mounting ends 7 are arranged coaxially, and their connecting line passes through the geometric center of the reflector support frame 4. The pair of second mounting ends 7 can be rotatably mounted between the two ends of the mounting component 3 in the same direction by deep groove ball bearings. The axis of rotation of the reflector support frame 4 is horizontal when it rotates, and this axis is defined as the pitch axis x2.

[0071] The reflector 5 can be a planar reflector made of fused silica material with a high-reflectivity coating. The reflector 5 is rotatably mounted on the reflector support frame 4. Specifically, the reflector 5 has a pair of third mounting ends 8, which can be short shafts made of stainless steel. The two third mounting ends 8 are coaxially arranged and the line connecting them passes through the optical center of the reflector 5. The top of the reflector support frame 4 can be vertically positioned with a pair of spaced-apart support plates. The pair of third mounting ends 8 can be rotatably mounted on the pair of support plates via miniature rolling bearings. The axis of rotation of the reflector 5 is perpendicular to the axis of rotation of the reflector support frame 4, and the axis of rotation of the reflector 5 is defined as the azimuth axis y2.

[0072] The drive assembly includes a first motor that drives the turntable to rotate, a second motor that drives the reflector support frame to rotate, and a third motor that drives the reflector to rotate. The first motor 9 can be a brushless DC motor, whose stator is fixed to the base 1 by bolts. The rotor of the first motor 9 can be coaxially connected to the first mounting end 6 of the turntable 2 through a coupling, and is used to drive the turntable 2 to rotate around the azimuth axis y1. The stator of the second motor 10 is mounted on the mounting component 3, and the rotor is coaxially fixed to one of the second mounting ends to drive the reflector support frame 4 to rotate, thereby adjusting the pitch angle of the reflector 5. The stator of the third motor 11 can be fixed to the reflector support frame 4 through a bracket (not shown in the figure), and the rotor is coaxially fixed to one of the third mounting ends to drive the reflector 5 to rotate, thereby adjusting the azimuth angle of the reflector 5. The second motor 10 and the third motor 11 can be rotary motors, such as frameless torque motors, micro brushless DC motors, voice coil motors, permanent magnet synchronous motors, etc., with voice coil motors and permanent magnet synchronous motors being preferred, and the appropriate type can be selected according to the actual situation.

[0073] The detection components include a first angle sensor, a second angle sensor, a third angle sensor, a beam position detector, and a temperature monitoring module. The first, second, and third angle sensors can all be commonly used sensors for measuring shaft rotation angles, such as optical encoders (incremental encoders, absolute encoders), rotary transformers, magnetic encoders, potentiometers (rotary variable resistors), capacitive encoders, and eddy current sensors (when using eddy current sensors, existing programs are needed to convert displacement changes into angular changes). The angle sensors can be installed using conventional techniques. The following example uses angle sensors with rotor and stator structures, such as rotary transformers / optical encoders, to illustrate their installation structure: The stator of the first angle sensor is connected to the base 1 via a mounting bracket, and the rotor is coaxially fixed to the first mounting end 6 of the turntable 2 via a coupling. The stator of the second angle sensor is fixed to the mounting component 3, and the rotor is coaxially connected to the second mounting end 7 of the reflector support frame 4. The stator of the third angle sensor is mounted on the reflector support frame 4, and the rotor is coaxially connected to the third mounting end 8 of the reflector 5.

[0074] The beam position detector is an independent optical receiving device installed outside the pointing mechanism in the target direction. It is fixedly installed as an independent component at the focal plane of the receiving optical path of the optical communication terminal. The target beam (beacon beam) reflected by the reflector 5 and finally converged is imaged on the photosensitive surface of the detector, which is used to generate horizontal and vertical deviation signals between the beam center and the detector center. In actual use, a four-quadrant detector can be selected as the beam position detector, which is a very mature technology in this field and will not be described in detail here.

[0075] The temperature monitoring module includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The first temperature sensor can be a PT1000 platinum resistance thermometer, which is attached to the center of the stator housing of the first motor 9 using thermally conductive silicone grease. The second temperature sensor can also be a PT1000 platinum resistance thermometer, attached to the stator housing of the second motor 10 using thermally conductive silicone grease. The third temperature sensor can be a DS18B20 digital temperature sensor, which can be installed on the side wall of the reflector support 4 to monitor its temperature changes. All temperature sensors are connected to the controller via cables.

[0076] The controller can be an embedded motion controller with multi-axis coordinated control function. The controller is communicatively connected to the first motor, the second motor, the third motor, the first angle sensor, the second angle sensor, the third angle sensor, the beam position detector, and the temperature monitoring module. Specifically, the controller is communicatively connected via cables to the drivers of the three motors, the reading heads of the three angle sensors, the signal processing circuit of the four-quadrant detector, and the three temperature sensors.

[0077] The controller has a pre-stored thermal deformation compensation model and executes an integrated control process that combines coarse and fine alignment with real-time thermal error compensation. There are several methods for constructing the thermal deformation compensation model; one such method is as follows:

[0078] 1. The model was constructed in a constant temperature laboratory (20°C ± 0.5°C), and the steps are as follows:

[0079] 1) Reference Calibration (A1): Start the mechanism to maintain zero torque on all motors (first motor, second motor, and third motor). After the mechanism reaches overall thermal equilibrium, use an external laser tracker to precisely calibrate the orientation of reflector 5 at this point, defining it as the optical zero point (pitch angle Δx=0, azimuth angle Δy=0). Simultaneously record the readings of the first, second, and third temperature sensors, denoted as reference temperatures T10, T20, and T30, respectively.

[0080] 2) Data Acquisition (A2): By programming and controlling the first motor 9 and the second motor 10 to operate at different speeds and duty cycles, and supplemented by controllable infrared heating lamps or hot air guns and other external temperature control devices, the stator housing of the first motor 9, the stator housing of the second motor 10, and the reflector support frame 4, or their adjacent areas, are individually, alternately, or in combination heated. For example, multiple operating conditions can be designed, including: heating only the vicinity of the first motor; heating the first and second motors simultaneously; heating the reflector support frame; and heating the support frame while the motors are running, etc., systematically generating about 10 different steady-state temperature distribution states on the mechanism. Under each steady state, the following operations are performed synchronously: ① Read the current values ​​T1, T2, T3 of the three temperature sensors; ② Use a laser tracker to measure the actual angular deviation of the center point of the reflector 5 relative to the optical zero position with high precision, and record it as the measured value (Δxm, Δym).

[0081] 3) Modeling (A3): Import the collected data sets {(T1,T2,T3), (Δxm, Δym)} into the computer to determine the quantitative mapping relationship between the temperature change at each monitoring point and the reflector angle deviation. This quantitative mapping relationship can be achieved through data processing and modeling methods. Specifically, in a preferred embodiment, considering that the thermal expansion of the material and the temperature rise are approximately linearly related within the normal operating temperature range, a multiple linear regression algorithm is preferably used to fit the multiple data sets. Using the temperature changes at three monitoring points (T1-T10, T2-T20, T3-T30) as independent variables, and the measured pitch angle deviation Δxm and azimuth angle deviation Δym as dependent variables, a set of optimal thermal deviation coefficients Kx1, Kx2, Kx3 and Ky1, Ky2, Ky3 can be obtained by solving the least squares method. Thus, the specific mathematical expressions of the thermal deformation compensation model are established as follows: Δx = Kx1×(T1 - T10) + Kx2×(T2 - T20) + Kx3×(T3 - T30); Δy = Ky1×(T1 - T10) + Ky2×(T2 - T20) + Ky3×(T3 - T30);

[0082] Wherein, Δx and Δy are the thermally induced angle deviations predicted by the model, and Kx1~Ky3 are coefficients (unit: μrad / °C) characterizing the quantitative relationship between temperature rise and angle deviation at each monitoring point. This set of coefficients, along with the reference temperatures (T10, T20, T30), is stored in the controller's non-volatile memory, thus completing the construction and storage of the model. It is understood that the above-described method using multiple linear regression is merely an illustrative example. Under the concept of this invention, those skilled in the art can also use other applicable data fitting or system identification algorithms (such as nonlinear regression, least squares support vector machines, etc.) to establish the quantitative mapping relationship between the temperature change and the angle deviation, as long as it can construct a predictive model that can be used for feedforward compensation based on experimental data.

[0083] In this technical solution, during system operation, the controller executes the main alignment process and the background thermal compensation process in parallel:

[0084] The master alignment process is as follows:

[0085] S1. The controller starts the first motor 9, driving the turntable 2 to rotate around the azimuth axis for a wide-range beam search. When the beam position detector first detects the target beam, the first motor 9 stops.

[0086] S2. The controller receives the beam position signal generated by the beam position detector, which includes horizontal and vertical deviations. The horizontal deviation signal is processed by a PID control algorithm to generate a drive command for the third motor 11. The third motor 11 drives the reflector 5 to rotate around the azimuth axis y2 to eliminate the horizontal deviation. When the horizontal deviation is less than the design value, the deviation is considered to have been eliminated. The vertical deviation drives the second motor 10, which in turn drives the reflector support frame 4 to rotate around the pitch axis x2 for correction.

[0087] S3. The controller generates a drive command for the second motor 10 based on the vertical deviation signal. The second motor 10 drives the reflector support frame 4 to rotate around the pitch axis x2 to eliminate the vertical deviation. When the vertical deviation is less than the design value, the deviation is considered to have been eliminated.

[0088] S3. When the beam position detector detects that the deviations in both the horizontal and vertical directions are less than the designed set threshold (e.g., 0.1 mrad), the controller outputs a lock signal to keep the second motor 10 and the third motor 11 in their current positions, thus completing the precise pointing of the beam.

[0089] The real-time thermal error compensation process (running in the background) is as follows:

[0090] B1. The controller synchronously acquires real-time temperature data T1(t), T2(t), and T3(t) from three temperature sensors at a certain frequency (e.g., 100Hz).

[0091] B2. The controller calls the stored thermal deformation compensation model, substitutes the real-time temperature and the reference temperature into the model formula, and calculates the pitch angle deviation Δx(t) and azimuth angle deviation Δy(t) caused by the current thermal state prediction in real time.

[0092] B3. The controller immediately generates compensation commands -Δx(t) and -Δy(t) that are equal in magnitude but opposite in direction to the predicted deviations Δx(t) and Δy(t). These feedforward compensation commands are superimposed in real time onto the drive commands being sent to the second motor 10 and the third motor 11 (these commands originate from the aforementioned precision alignment closed loop or locked state). This process continues, thus actively canceling out thermal drift before the main alignment closed loop detects it.

[0093] The beneficial effects of this technical solution are that it combines a coarse-precision integrated mechanical structure, a hierarchical closed-loop control process, and real-time thermal error feedforward compensation based on experimental calibration, resulting in significant synergistic effects. Firstly, the mechanism simultaneously possesses wide-range acquisition and high-precision pointing capabilities. The coarse pointing mechanism acquires the beam by rotating at a large angle, while the fine pointing mechanism can precisely adjust the beam direction by rotating at a certain angle, ultimately sending the beam to the designated direction. The integrated coarse-precision pointing mechanism has a smaller space occupancy, smaller overall volume, and lower cost. Furthermore, both mechanisms share a single control system, improving the pointing accuracy and response speed of the optical communication system, thereby increasing work efficiency. Simultaneously, the overall structure is simple and reliable, easy to install and maintain, and suitable for various optical communication application scenarios. Secondly, through multi-sensor feedback and closed-loop control, it achieves combined coarse and fine beam pointing adjustment. Angle sensors provide high-precision angle feedback, and beam position detectors provide final position verification, ensuring the system achieves the required pointing accuracy. The control algorithm employs a hierarchical adjustment strategy, first coarse adjustment and then fine adjustment, ensuring both wide-range search capability and high-precision positioning requirements. The entire control process boasts a high degree of automation and rapid response, meeting the stringent beam pointing requirements of optical communication systems. Furthermore, the intelligent control flow of "coarse scanning and acquisition, followed by dual-axis fine-tuning and alignment, and finally locking" significantly improves the speed, accuracy, and automation of beam acquisition and alignment. Most importantly, it innovatively introduces a thermal deformation compensation model established through experimental calibration. This model proactively predicts and compensates for pointing errors caused by structural thermal deformation due to motor heating and changes in ambient temperature, based on real-time monitored temperature data. This ensures extremely high pointing accuracy and stability even under varying temperature conditions. The organic combination of these three elements solves the industry challenges of large space occupation, low response efficiency, and poor thermal stability inherent in traditional discrete mechanisms, providing a high-performance, high-reliability core pointing component for free-space optical communication systems.

[0094] In another technical solution, the bottom circumferential of the mounting component 3 is provided with multiple mounting holes, and the upper surface of the turntable 2 is provided with threaded holes at positions corresponding to the mounting holes;

[0095] The mounting component 3 is connected to the turntable 2 via multiple isolation connection assemblies, each corresponding to a different mounting hole. Each isolation connection assembly includes a bolt 12 and an elastic damping element. The elastic damping element is press-fitted into the mounting hole and has a through hole at its center for the bolt 12 to pass through. The bolt 12 passes sequentially through the through hole of the elastic damping element and a washer 13 located below the mounting hole, and finally screws into the threaded hole of the turntable 2. The shank of the bolt 12 does not contact the inner wall of the mounting hole or the inner wall of the through hole of the elastic damping element.

[0096] The rotor of the first motor 9 is connected to the first mounting end 6 of the turntable 2 via a flexible coupling;

[0097] The control method executed by the controller further includes: in step S1, when the beam position detector detects the target beam for the first time, the controller controls the first motor 9 to decelerate at a first deceleration, and after the rotation speed drops to a set value, it stops smoothly at a second deceleration lower than the first deceleration to suppress the stopping impact of the turntable 2; after completing step S1 and the first motor 9 stops, a preset delay time is waited for the residual vibration of the turntable 2 to be attenuated by the elastic damping element before executing steps S2 and S3;

[0098] In the above technical solution, the mounting component 3 and the turntable 2 are connected by an isolation connection assembly to achieve vibration suppression, as detailed below:

[0099] The bottom circumference of mounting component 3 can be evenly divided into six mounting holes, each with a diameter of 8mm. M6 threaded blind holes can be machined on the upper surface of turntable 2 at positions corresponding to these mounting holes. The connection between mounting component 3 and turntable 2 uses six isolation connection assemblies, each including an M6 socket head cap screw 12 and an elastic damping element. The elastic damping element can be a cylindrical shock-absorbing pad made of polyurethane material, with an outer diameter of 8mm and a height of 5mm, and a core with a through hole of 4.5mm diameter. During assembly, the elastic damping element is first pressed into the mounting hole of mounting component 3, then the bolt 12 is passed sequentially through a stainless steel washer 13, the through hole of the elastic damping element, and finally screwed into the threaded hole of turntable 2. The shank diameter of bolt 12 is 4mm, maintaining a gap of approximately 0.25mm between it and the inner wall of the mounting hole and the inner wall of the through hole of the elastic damping element, ensuring no contact and allowing vibration to be primarily attenuated through the elastic damping element.

[0100] The rotor of the first motor 9 is connected to the first mounting end 6 of the turntable 2 via a flexible coupling. This coupling can be a plum blossom-shaped flexible coupling, whose aluminum alloy body can compensate for a certain coaxiality error and absorb torque shocks during start-up and shutdown.

[0101] In executing the control method, the controller incorporates a specific stopping strategy in step S1. When the beam position detector first detects the target beam, the controller controls the first motor 9 to initially decelerate with a larger first deceleration. Once the rotational speed of the turntable 2 drops to a lower set value, a smaller second deceleration is used for a smooth stop, thereby suppressing the inertial impact caused by the sudden stop of the turntable 2. After completing step S1 and the first motor 9 stops, the controller waits for a preset delay time. This delay allows sufficient time for the inevitable residual vibrations after the turntable 2 stops to be attenuated by the aforementioned elastic damping element. After the mechanism stabilizes, subsequent fine-tuning steps S2 and S3 are executed.

[0102] It should be noted that the first deceleration, second deceleration, and delay time mentioned above are set according to the actual situation and can be determined experimentally in advance. For example, the delay time can be determined as follows: 1) Experimental setup: Temporarily install a high-precision vibration sensor (such as a laser vibrometer or accelerometer) on the turntable or mounting component to monitor the residual vibration amplitude; at the same time, ensure that the beam position detector is working properly; 2) Excitation and measurement: Control the first motor to drive the turntable to run at different speeds and stop abruptly at different speed points to simulate the maximum mechanical impact. Record the time t required for the vibration amplitude monitored by the vibration sensor to decay to the allowable error range of the system's fine tracking (e.g., one-fifth of the fine tracking beam deviation threshold) after the emergency stop command is issued; 3) Determine T: Take the maximum value T among the times t obtained under all test conditions. max Then multiply by a safety factor k (usually 1.2-1.5, k=1.2-1.5) to obtain the preset delay time T=k×T max This value is stored in the controller's built-in non-volatile memory.

[0103] The beneficial effects of this technical solution are that, through a combination of mechanical isolation and control strategies, vibration interference caused to the fine pointing mechanism when the coarse pointing mechanism stops after a large range of rotation is effectively suppressed. The elastic damping connection assembly and flexible coupling provide vibration isolation in terms of mechanical structure, while the two-stage deceleration and delay strategy avoids impacts and allows residual vibration to decay from a control logic perspective. Together, these measures ensure a stable platform during the fine pointing adjustment stage, ultimately improving the system's pointing accuracy and stability.

[0104] In another technical solution, a pair of second mounting ends 7 of the reflector support frame 4 are respectively rotatably mounted at both ends of the mounting member 3 in the same direction by a pair of first precision bearings with high axial and radial rigidity;

[0105] The second motor 10 of the precision pointing motor mechanism is a frameless torque motor. The rotor of the second motor 10 is fixedly sleeved on the second mounting end 7 of the reflector support frame 4 and located within the support span formed by a pair of first precision bearings. The stator of the second motor 10 is fixedly mounted on the mounting member 3 so that the stator of the second motor 10 directly drives the rotor of the second motor 10, thereby driving the reflector support frame 4 to rotate around the pitch axis.

[0106] The pair of third mounting ends 8 of the reflector 5 are rotatably mounted on the circumferential inner wall of the reflector support frame 4 via a pair of second precision bearings.

[0107] In the above technical solution, a pair of second mounting ends 7 of the reflector support frame 4 are rotatably mounted at both ends of the mounting component 3 in the same direction via a pair of first precision bearings. These first precision bearings can be P4 grade angular contact ball bearings, which have high axial and radial rigidity, an inner diameter of 10mm, an outer diameter of 26mm, and a width of 8mm. The two bearings can be installed in pairs, in a back-to-back configuration, to provide a stable support span. This span can be designed to be 80mm, thereby effectively limiting the radial and axial movement of the reflector support frame 4 during rotation and ensuring the rotational accuracy of the pitch axis x2.

[0108] The second motor 10 of the precision pointing motor mechanism can be a frameless torque motor with a rated torque of 2 Nm and a peak torque of 6 Nm. The rotor of the second motor 10 is directly interference-fitted onto one of the second mounting ends 7 of the reflector support frame 4, and the rotor's mounting position is precisely located within the support span formed by a pair of first precision bearings. This arrangement places the drive point between the two support points, forming a stable simply supported beam structure, which is beneficial for improving transmission stiffness and control bandwidth. The stator of the second motor 10 is bolted to the mounting part 3, maintaining a precise air gap fit with the rotor, so that the stator can directly drive the rotor, achieving backlash-free torque transmission, thereby driving the reflector support frame 4 to rotate with high precision around the pitch axis x2.

[0109] The pair of third mounting ends 8 of the reflector 5 are rotatably mounted on the circumferential inner wall of the reflector support frame 4 via a pair of second precision bearings. These second precision bearings can be miniature deep groove ball bearings with a precision grade of ABEC-7, an inner diameter of 8mm, an outer diameter of 16mm, and a width of 5mm. The outer ring of the bearing is fitted with the bearing seat hole on the reflector support frame 4 using a transition fit, while the inner ring is fitted with the third mounting ends 8 using an interference fit. This pair of bearings provides high-precision rotational support for the reflector 5's rotation around the azimuth axis y2, and its low friction and low runout characteristics ensure the pointing stability and repeatability of the reflector 5 during fine-tuning.

[0110] The beneficial effects of adopting this technical solution are that, through the high-rigidity symmetrical bearing assembly and the direct drive motor integrated between the bearing assemblies, the structural rigidity of the pitch axis of the fine-tuning system is fundamentally strengthened, the connection strength between the reflector and the reflector support frame is improved, and the extreme stability of the reflector 5 position during fine tracking is ensured. The frameless torque motor directly drives the second mounting end 7, eliminating the backlash, elastic deformation, and friction that may be caused by intermediate transmission links such as gears and belts. This results in higher resolution, faster response speed, and better control precision for the pitch angle adjustment of the reflector 5, meeting the stringent requirements of optical communication systems for fine pointing mechanisms.

[0111] Another technical solution also includes:

[0112] The first limit switch is set at the extreme position of the rotation path of the reflector support 4;

[0113] The second limit switch is set at the extreme position of the rotation path of the reflector 5;

[0114] The normally closed contacts of the first limit switch and the second limit switch are connected in series to the drive power circuit of the second motor 10 and the third motor 11. When any limit switch is triggered, the drive power of the corresponding motor is physically cut off.

[0115] In the above technical solution, the mechanism also includes a first limit switch and a second limit switch, which are used to limit the mechanical rotation range of the reflector support 4 and the reflector 5, respectively, to prevent mechanical collision or structural damage caused by excessive movement. The first limit switch can be a miniature lever roller type limit switch with a rated current of 10A. This switch can be fixed to the mounting part 3 by a mounting bracket, and the trigger position of its lever roller arm is precisely set at the limit position of the reflector support 4's rotation range around the pitch axis x2, such as a pitch angle of +5.5 degrees or -5.5 degrees. This position leaves a safety margin of about 0.5 degrees compared to its maximum allowable angle during normal operation (such as ±5 degrees). When the reflector support 4 rotates to this limit position, its outer edge will press down the lever roller of the first limit switch, triggering the switch action.

[0116] The second limit switch can be a basic micro switch with a rated current of 5A. This switch can be fixed to the reflector support bracket 4 via another mounting bracket. The top of its trigger button is precisely set at the extreme position of the reflector 5's rotation around the azimuth axis y2, such as an azimuth angle of +5.5 degrees or -5.5 degrees, with a safety margin of approximately 0.5 degrees. When the reflector 5 rotates to this extreme position, its side wall or mounting end will contact and press down the trigger button of the second limit switch, triggering the switch to operate.

[0117] The normally closed contacts of the first and second limit switches are connected in series to the drive power supply circuits of the second motor 10 and the third motor 11. Specifically, the live wire of the external drive power supply first passes through the normally closed contact of the first limit switch, then a lead from that contact connects to the normally closed contact of the second limit switch, and finally a lead from the second limit switch is simultaneously connected to the drive power input terminals of both the second motor 10 and the third motor 11. This means that the power supply to both motors must simultaneously pass through the series circuit of these two normally closed contacts.

[0118] The beneficial effect of this technical solution is that when either the reflector support 4 or the reflector 5 rotates to its mechanical limit position due to control abnormality or other malfunction, the corresponding limit switch will be triggered. The normally closed contact of the switch will immediately switch from the closed state to the open state. Since the contacts of the two switches are connected in series, the opening of either contact will immediately physically cut off the drive power supply to the second motor 10 and the third motor 11. This cutoff is at the hardware level and does not rely on the software judgment of the controller, thus ensuring that even if the controller malfunctions or the program runs away, the operation of the precision pointing motor can be reliably stopped. This effectively prevents accidents such as mechanical interference, jamming, or damage caused by excessive rotation of the mechanism, protecting the precision reflector 5 and the transmission structure.

[0119] In practical use, after troubleshooting, the limit switch can be reset through various means. The following describes an automatic control method for resetting the limit switch: The normally closed contacts of the first and second limit switches are connected in series to the main drive power circuit of the second motor 10 and the third motor 11. The main drive power circuit is powered by an external main power supply, and its live wire is connected in series with the normally closed contacts of the first and second limit switches, and then connected to the power input terminals of the drivers for the second motor 10 and the third motor 11. This is the first line of defense for ensuring safety.

[0120] The integrated coarse and fine pointing mechanism for optical communication also includes a reset control module. This module comprises an independent reset power supply circuit and a controlled switching device (such as relay K1). The reset power supply circuit can be composed of a low-power auxiliary power supply (such as 24V DC). The normally open contact of relay K1 is connected in series between the output terminal of the reset power supply circuit and the power input terminal of the motor driver. The controller is connected to the coil of relay K1 to control its on / off state. When the system is operating normally or when the limit switch is just triggered, relay K1 is in a de-energized state, its normally open contact is open, and the reset power supply circuit is completely isolated from the motor.

[0121] When a reset is required (e.g., a reset command is issued by the host computer), the controller executes the following automatic process: First, the controller determines which axis (pitch or azimuth axis) overtravel triggered the limit switch (this can be determined based on the motor's last movement state or a newly added independent signal detection circuit). The controller sends a closing command to relay K1, temporarily connecting the reset power supply circuit to the driver of the corresponding motor (second motor 10 or third motor 11). The controller generates a low-speed, low-torque reverse rotation command, driving the motor to slowly exit its limit position. The controller monitors the status of the triggered limit switch in real time (its signal can be acquired via the I / O port). Once it detects that its normally closed contact has reopened (indicating the mechanism has exited its limit position), the controller immediately stops the motor and disconnects relay K1. At this time, the main drive power supply circuit is restored, and the system returns to normal standby mode, awaiting new operating commands. This automatic control method achieves fully automatic reset after overtravel protection, avoiding the inconvenience and potential risks of manual intervention, further improving the intelligence and reliability of the equipment.

[0122] In another technical solution, a main conductive slip ring is also included. The rotor end of the main conductive slip ring is coaxially fixed with the turntable 2 and rotates with it, while the stator end is fixed with the base 1. The power supply and signal transmission cables of the second motor 10, the third motor 11, the first angle sensor, the second angle sensor, the third angle sensor, and the beam position detector are connected to the external controller and power supply via the main conductive slip ring.

[0123] At least one third mounting end 8 of the reflector 5 is a hollow shaft structure, and a miniature conductive slip ring is coaxially disposed inside the hollow shaft structure; the rotor of the miniature conductive slip ring is fixedly connected to the third mounting end 8 and rotates with the reflector 5, and the stator is fixedly connected to the reflector support frame 4; the power supply and signal transmission cables of the third motor 11 and the third angle sensor are connected to the rotor end of the main conductive slip ring via the miniature conductive slip ring;

[0124] In the above technical solution, this mechanism also includes a main conductive slip ring to solve the cable entanglement problem during continuous rotation of the turntable 2. This main conductive slip ring can be a standard through-hole type, with 12 channels, a rated current of 5A, and a maximum speed of 200rpm. The rotor end of the main conductive slip ring is coaxially fixed to the rotation center axis of the turntable 2 via a key connection and rotates with the turntable 2. Its stator end is fixedly connected to the base 1 via a mounting flange, keeping it stationary. The power supply and signal transmission cables for all components that need to rotate with the turntable 2, such as the second motor 10, the third motor 11, the first angle sensor, the second angle sensor, the third angle sensor, and the beam position detector, are first gathered and bundled within the mounting component 3, and then all connected to the rotor end of the main conductive slip ring. The cables for the external controller and power supply are connected to the stator end of the main conductive slip ring. By sliding the brush inside the slip ring into contact with the ring track, a continuous power and signal connection is achieved between the stationary base 1 and the rotating component, ensuring that the turntable 2 can rotate continuously 360 degrees without restriction on the azimuth axis y1.

[0125] To further address the lead wire issue when the reflector 5 rotates around the azimuth axis y2, one of the third mounting ends 8 of the reflector 5 is designed as a hollow shaft structure with an inner diameter of 6mm. A miniature conductive slip ring is coaxially mounted and hidden within the internal cavity of this hollow shaft structure. This miniature conductive slip ring can have four channels and a rated current of 1A. The rotor of the miniature conductive slip ring is threadedly connected to the end of the third mounting end 8 and rotates with the reflector 5. Its stator is fixed to the reflector support frame 4 via a fixed bracket and remains stationary. The motor power line of the third motor 11 and the signal line of the third angle sensor are first straightened on the back of the reflector 5, then passed through the hollow shaft, and connected to the rotor end of the miniature conductive slip ring. The cable leading from the stator end of the miniature conductive slip ring is then laid along the reflector support frame 4 and the mounting component 3, and finally connected to the rotor end of the main conductive slip ring, thus forming a complete electrical path.

[0126] The beneficial effect of this technical solution is that by employing a two-stage wiring scheme combining a main conductive slip ring and a miniature conductive slip ring, the cable management challenges arising from the multiple rotational degrees of freedom in the integrated coarse and fine pointing mechanism are systematically solved. The main conductive slip ring is responsible for handling all energy and signal transmission on the large-scale continuous rotation of the turntable 2, while the miniature conductive slip ring specifically handles the leads required for the precise rotation of the nested reflector 5. This layout avoids cable entanglement, breakage, or stress fatigue during rotation, ensuring a continuous and stable power supply and high reliability of signal transmission. Simultaneously, it minimizes the interference of the wiring harness on the mechanism's motion accuracy and dynamic performance, making it a key supporting technology for ensuring the mechanism achieves its intended functions.

[0127] In another technical solution, an acceleration sensor is also included, which is disposed on the reflector or the reflector support frame, for detecting high-frequency vibration of the reflector, and the acceleration sensor is communicatively connected to the controller;

[0128] The controller also has a pre-stored disturbance propagation model, which was obtained through experimental identification. This disturbance propagation model describes the dynamic relationship between the acceleration sensor signal and the angle disturbance of the reflector. The controller also executes the following control flow:

[0129] C1. The controller acquires the vibration signal detected by the acceleration sensor in real time;

[0130] C2. The controller, based on the disturbance transmission model, calculates the predicted mirror angle disturbance component in real time from the vibration signal;

[0131] C3. The controller uses the inverse vector of the predicted disturbance component as a feedforward compensation command, and fuses it with the fine tracking command based on the beam position detector and the thermal error compensation command based on the thermal deformation compensation model to jointly drive the second motor and the third motor.

[0132] In the above technical solution, the accelerometer is preferably a miniature, high-bandwidth, low-noise MEMS (Micro-Electro-Mechanical Systems) triaxial accelerometer with a measurement range of ±50g and a bandwidth of not less than 500Hz to meet the requirements for detecting high-frequency vibration signals. One mounting structure for the accelerometer is as follows: A shallow, flat mounting surface is created in the non-optical working area of ​​the reflector (e.g., the center of the back). High-strength epoxy resin is used to firmly and smoothly adhere the accelerometer's encapsulation base to this mounting surface, aligning its two mutually perpendicular sensing axes with the reflector's pitch axis (x2) and azimuth axis (y2) (positioning can be assisted by a mounting fixture). The sensor's signal line is led out through a pre-reserved slot on the reflector support frame 4 and ultimately connected to the controller's analog / digital input interface. In another mounting structure, the accelerometer can also be mounted on the outer wall of the reflector support frame 4 near the reflector's rotation center, indirectly reflecting the reflector's vibration state by measuring the vibration of the support structure itself.

[0133] The disturbance propagation model is constructed using a system identification method based on actual measurements. Its core is to establish the dynamic mathematical relationship between the acceleration signal and the mirror angle disturbance. The specific steps are as follows:

[0134] 1. Experimental Excitation and Data Acquisition System Setup: The fully assembled pointing mechanism is placed on a vibration isolation platform to isolate it from environmental vibration interference. A broadband vibration excitation source, such as an electromagnetic exciter, is set up next to the mechanism. This exciter is connected to a non-critical part of the base 1 via a force sensor. This non-critical part refers to a structurally robust location capable of reliably transmitting vibration excitation, but far from all precision motion axes (such as y1, x2, y2 axes) and optical elements (reflector surfaces), such as the side of the base, to inject a known, broadband (e.g., 5Hz-400Hz) vibration excitation signal (such as white noise or swept frequency signal) into the system. A high-precision laser displacement sensor or laser Doppler vibrometer is set up, with its measuring beam aimed at the uncoated area of ​​the edge of the reflector 5, to directly measure the microscopic displacement or velocity in the normal direction of the reflector surface in a non-contact manner, and calculate the deviation values ​​of the pitch angle θx(t) and azimuth angle θy(t) in real time through geometric relationships. This device serves as a true reference for model training.

[0135] 2. Data Synchronous Acquisition: The exciter is started, outputting a preset excitation signal. The controller synchronously acquires three time-series signals at a high sampling rate (e.g., 5kHz): a) Input signal: the triaxial raw voltage signal output by the accelerometer mounted on the reflector. b) Output true value signal: the reflector pitch angle deviation θx(t) and azimuth angle deviation θy(t) measured by an external high-precision measuring instrument. The experiment is repeated under various excitation intensities and several typical static attitudes of the reflector, acquiring multiple sets of data pairs covering the expected dynamic range of the system for subsequent system identification.

[0136] 3. System Identification and Model Acquisition: The acquired synchronization data {acceleration signal a(t), angle θx(t), θy(t)} is imported into system identification software (such as MATLAB). A subspace identification algorithm (e.g., N4SID algorithm) is used to fit a low-order discrete state-space model from the data for both the pitch and azimuth channels. This model describes the dynamic transfer characteristics from acceleration input to angle output. The identified model is validated by checking its prediction accuracy using a set of data not involved in the identification process. After confirming the model's effectiveness, model order reduction is performed to obtain a simplified model (e.g., 4th-6th order) suitable for real-time controller operation, while maintaining the fitting accuracy in key frequency bands.

[0137] 4. Model Storage: The parameters (e.g., coefficients of the state-space matrix) of the finalized simplified disturbance transfer model are pre-stored in the non-volatile memory of the controller. These parameters, together with the installation location and sensitivity information of the accelerometer, constitute the complete disturbance transfer model.

[0138] In this technical solution, during system operation, the controller simultaneously executes the following high-frequency disturbance suppression control process while concurrently performing the main alignment process and the thermal error compensation process, as follows:

[0139] C1. Signal Acquisition and Processing: The controller reads the signal from the accelerometer in real time, performs preprocessing such as coordinate transformation and filtering (e.g., high-pass filtering to isolate low-frequency motion), and calculates the effective vibration acceleration components ax(t) and ay(t) along the current reflector pitch axis x2 and azimuth axis y2.

[0140] C2. Disturbance Prediction: The controller calls the pre-stored disturbance propagation model (i.e., the state-space model), taking ax(t) and ay(t) as real-time inputs. By executing the model's state update and output equations, it calculates (predicts) in real-time the pitch angle disturbance component Δxp(t) and azimuth angle disturbance component Δyp(t) caused by the current high-frequency vibration that the reflector is about to experience. This calculation is completed within milliseconds.

[0141] C3. Feedforward Compensation and Multi-Instruction Fusion: Within each control cycle, the controller synchronously performs the following operations to generate the final drive instruction, as follows:

[0142] 1) Command Calculation: Based on the predicted disturbance components Δxp(t) and Δyp(t) obtained in step C2, the controller generates corresponding high-frequency feedforward compensation commands. Specifically, the high-frequency feedforward compensation for the pitch axis x2 is -Gx×Δxp(t), and the high-frequency feedforward compensation for the azimuth axis y2 is -Gy×Δyp(t). Gx and Gy are feedforward gain coefficients, typically tuned experimentally to values ​​close to 1.

[0143] 2) Command Fusion: The controller fuses the above-mentioned high-frequency feedforward compensation with commands from the other two control channels in real time, specifically as follows: The pitch axis x2 fine tracking command U{a,x}(t) and azimuth axis y2 fine tracking command U{a,y}(t) from the fine tracking closed loop; the pitch axis thermal compensation feedforward command U{b,x}(t) and azimuth axis thermal compensation feedforward command U{b,y}(t) from the thermal deformation compensation model. After fusion, the final pitch axis integrated drive command Ux(t) and azimuth axis integrated drive command Uy(t) are generated, calculated as follows: Ux(t) = U{a,x}(t) + U{b,x}(t) - Gx×Δxp(t); Uy(t) = U{a,y}(t) + U{b,y}(t) – Gy×Δyp(t);

[0144] 3) Command output: The controller sends Ux(t) to the driver of the second motor 10 in real time to drive the reflector support frame to rotate around the pitch axis x2; at the same time, it sends Uy(t) to the driver of the third motor 11 in real time to drive the reflector to rotate around the azimuth axis y2.

[0145] Thus, steps C1 to C3 constitute a complete control loop, which is executed continuously in each control cycle. This actively suppresses the beam deviation caused by high-frequency vibration before it becomes observable, significantly improving the tracking accuracy and stability of the system under dynamic disturbances.

[0146] The beneficial effects of this technical solution are as follows: by introducing an accelerometer, an experimentally identified disturbance transmission model, and multi-command fusion feedforward control, significant and synergistic technical effects are achieved. The accelerometer can directly detect high-frequency vibrations acting on the reflector (such as airflow turbulence or platform micro-vibrations) and use a pre-stored model to predict the resulting angular disturbances in real time, thereby generating advanced compensation commands. This feedforward command is vector-fused with the original fine tracking closed-loop command and thermal error compensation command to jointly drive the fine pointing motor. Its core effect is to transform high-frequency, random disturbances that traditional passive feedback control cannot effectively handle into predictable and actively canceled objects, thereby significantly expanding the effective control bandwidth of the system and significantly reducing beam pointing jitter and tracking residual errors. This not only improves pointing accuracy and stability in dynamic disturbance environments (such as outdoor wind loads and mobile platforms) but also enhances the reliability and anti-interference capability of the entire communication link. It complements the thermal compensation system, jointly achieving full-spectrum, active error suppression from low-frequency thermal drift to high-frequency random vibration, giving this integrated coarse and fine pointing mechanism excellent environmental adaptability and high performance.

[0147] In another technical solution, the mounting component 3 includes a pair of vertical plates 301 and a top plate 302 horizontally disposed between the pair of vertical plates 301. Both ends of the top plate 302 are slidably connected to the corresponding vertical plates 301 and slide vertically. A protective cover 14 is provided at the bottom of the top plate 302. It also includes a drive telescopic rod, the drive end of which is connected to the top plate 302 to drive the top plate 302 to rise and fall. The drive telescopic rod is connected to the controller, which executes the following control flow:

[0148] When the reflector 5 is not in use, the controller starts the second motor 10, which drives the reflector support frame 4 to rotate so that the reflector support frame 4 is facing the protective cover 14. The controller starts the third motor 11 to drive the reflector 5 to rotate to a horizontal position. Then the controller starts the drive telescopic rod, which drives the top plate 302 to descend to the protective cover 14 and fasten it onto the reflector 5 to protect the reflector 5.

[0149] In the above technical solution, the mounting component 3 includes a pair of vertical plates 301 and a top plate 302 horizontally arranged between the pair of vertical plates 301. Both ends of the top plate 302 can be slidably connected to the corresponding vertical plates 301 via linear slide rail pairs, enabling it to rise and fall smoothly in the vertical direction. The linear slide rail pairs can be miniature ball bearing linear guides. A protective cover 14 is provided at the bottom center of the top plate 302, with the opening of the protective cover 14 facing downwards. The reflector support frame 4 is preferably a circular flat plate. When the opening end of the protective cover 14 contacts the top surface of the reflector support frame 4, the reflector 5 can be enclosed inside for protection.

[0150] It also includes a drive telescopic rod, which can be an electric push rod. There are several installation structures for the drive telescopic rod; one is described below: the drive telescopic rod is an electric push rod, the cylinder of which is fixed to the base 1 by a bracket and located on one side of the turntable. The drive end of the electric push rod is connected to an L-plate, and the other end of the L-plate extends above and connects to the top plate 302, thereby driving the top plate 302 to rise and fall. Alternatively, another installation structure is also described: the drive telescopic rod is an electric push rod, the cylinder of which is fixed above the top plate 302 of the mounting component 3 by a bracket, and the drive end of the push rod is threaded downwards to the center of the top plate 302. The motor drive line of this drive telescopic rod is connected to the input / output port of the controller to drive the top plate 302 to rise and fall.

[0151] The controller executes the following automated protection control method. When the system determines that the reflector 5 has stopped working or is in a standby state of not being used, the controller first starts the second motor 10. The second motor 10 drives the reflector support frame 4 to rotate around the pitch axis x2 until the open end of the reflector support frame 4 is directly facing the protective cover 14 at the bottom of the top plate 302. This position can be defined as a 0-degree pitch angle. Subsequently, the controller starts the third motor 11, which drives the reflector 5 to rotate around the azimuth axis y2 to a horizontal position. This position can be defined as a 0-degree azimuth angle, so that the mirror surface of the reflector 5 faces upward and is parallel to the protective cover 14. After the reflector 5 has moved into position and stabilized, the controller sends a descent command to the drive telescopic rod. The drive telescopic rod drives the top plate 302 to descend smoothly along the guide rail on the vertical plate 301 until the protective cover 14 completely covers the reflector 5, effectively protecting it from dust, water vapor, external impacts, and other possible contamination or damage.

[0152] The beneficial effects of adopting this technical solution are that the protection system achieves automated protection of the precision optical component, the reflector 5. By coordinating the second motor 10, the third motor 11, and the drive telescopic rod through the controller, the reflector 5 can be automatically moved to a safe position and covered. The entire process requires no manual intervention, improving operational convenience and reliability, and avoiding damage that may be caused by human negligence or improper operation. The design of the protective cover 14 provides effective physical isolation. When the protective cover 14 is placed on the reflector 5, it can prevent dust, particulate matter, moisture, and other pollutants in the environment from directly settling or contacting the optical surface of the reflector 5, reducing the frequency of cleaning and maintenance, and helping to maintain the long-term high reflectivity and optical performance of the reflector 5. At the same time, the robust protective cover can also resist accidental collisions or impacts to a certain extent, protecting the internally fragile reflector 5 and the precision support and adjustment mechanism from mechanical damage. Overall, by integrating an automated protective device into the motion mechanism, proactive, reliable, and safe protection measures are provided for the core optical components of the optical communication pointing mechanism, reducing maintenance costs and playing a positive role in ensuring the long-term stable operation of the equipment in complex environments and extending its service life.

[0153] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the coarse-fine integrated pointing mechanism of this invention for optical communication will be readily apparent to those skilled in the art.

[0154] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A coarse and fine integrated pointing mechanism for optical communication, characterized in that, include: A base has a turntable rotatably mounted on its top. The turntable's rotation axis is vertical and is the azimuth axis y1. A cross-shaped mounting component is fixedly connected to the top of the turntable. A reflector support frame is rotatably mounted between the two ends of the mounting component in the same direction. The reflector support frame's rotation axis is horizontal and is the pitch axis x2. A reflector is rotatably mounted on the reflector support frame. The reflector's mirror surface faces outward. The reflector's rotation axis is horizontal and is the azimuth axis y2, which is perpendicular to the pitch axis x2. The drive assembly includes a first motor for driving the turntable to rotate, a second motor for driving the reflector support frame to rotate, and a third motor for driving the reflector to rotate. The detection assembly includes a first angle sensor for detecting the rotation angle of the azimuth axis y1, a second angle sensor for detecting the rotation angle of the pitch axis x2, a third angle sensor for detecting the rotation angle of the azimuth axis y2, a beam position detector, and a temperature monitoring module. The beam position detector is used to detect the position deviation of the beam, and the temperature monitoring module is used to monitor the temperature of the first motor, the second motor, and the reflector support frame. The controller is communicatively connected to the first motor, the second motor, the third motor, the first angle sensor, the second angle sensor, the third angle sensor, the beam position detector, and the temperature monitoring module. The controller has a pre-stored thermal deformation compensation model. Based on the monitoring data of the temperature monitoring module and the thermal deformation compensation model, the controller performs real-time thermal error compensation on the drive commands of the second motor and the third motor.

2. The coarse and fine integrated pointing mechanism for optical communication as described in claim 1, characterized in that, The controller executes the following control flow: S1. The controller starts the first motor, driving the turntable to rotate around the azimuth axis y1 until the beam position detector detects the target beam and stops the first motor. S2. The controller receives the horizontal and vertical deviation signals of the beam generated by the beam position detector. Based on the horizontal deviation signal, it generates a third motor drive command and sends it to the third motor. The third motor drives the reflector to rotate around the azimuth axis y2 to eliminate the horizontal deviation. S3. The controller generates a second motor drive command based on the vertical deviation signal and sends it to the second motor. The second motor drives the reflector support frame to rotate around the pitch axis x2 to eliminate the vertical deviation. S4. When the beam position detector detects that both the horizontal and vertical deviations are less than the set thresholds, the controller locks the second and third motors.

3. The coarse and fine integrated pointing mechanism for optical communication as described in claim 2, characterized in that, The temperature monitoring module includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The first temperature sensor is installed on the stator housing of the first motor, the second temperature sensor is installed on the stator housing of the second motor, and the third temperature sensor is installed on the reflector support frame. The steps for constructing the thermal deformation compensation model are as follows: A1. Under constant reference temperature conditions, determine the initial alignment position of the reflector as the zero position, and simultaneously record the temperature values ​​indicated by the first temperature sensor, the second temperature sensor, and the third temperature sensor at this time as the reference temperature of each sensor. A2. By controlling the first motor and / or the second motor to operate under different working conditions, or by combining external temperature control methods, the mechanism can generate different temperature distribution states; under each stable temperature state, the current temperature value of each temperature sensor is read synchronously, and the current actual angle deviation value of the reflector relative to the zero position is obtained by actual measurement using measuring instruments. A3. Process the multiple sets of temperature values ​​and actual angle deviation values ​​collected synchronously in step A2 to determine the quantitative mapping relationship between the temperature change at each monitoring point and the angle deviation of the reflector, and define the mapping relationship as the thermal deformation compensation model. The control process for real-time thermal error compensation by the controller is as follows: B1. The controller periodically collects real-time temperature data from the first temperature sensor, the second temperature sensor, and the third temperature sensor; B2. The controller calls the thermal deformation compensation model and calculates the predicted values ​​of thermally induced pitch angle deviation Δx and azimuth angle deviation Δy based on the real-time temperature data and the reference temperature value. B3. The controller uses -Δx and -Δy as feedforward compensation values ​​to generate corresponding compensation instructions, which are then superimposed on the drive instructions sent to the second motor and the third motor.

4. The coarse and fine integrated pointing mechanism for optical communication as described in claim 3, characterized in that, The mounting component has multiple mounting holes circumferentially opened at its bottom, and the upper surface of the turntable has threaded holes at positions corresponding to the mounting holes. The mounting component is connected to the turntable via multiple isolation connection assemblies, each corresponding to a specific mounting hole. Each isolation connection assembly includes a bolt and an elastic damping element. The elastic damping element is press-fitted into the mounting hole and has a through hole at its center for the bolt to pass through. The bolt passes sequentially through the through hole of the elastic damping element and a washer located below the mounting hole, and finally screws into the threaded hole of the turntable. The shank of the bolt does not contact the inner wall of the mounting hole or the inner wall of the through hole of the elastic damping element. The bottom of the turntable is coaxially provided with a first mounting end, and the rotor of the first motor is connected to the first mounting end through a flexible coupling. The controller executes the following control flow: In step S1, when the beam position detector detects the target beam for the first time, the controller controls the first motor to decelerate at a first deceleration. After the rotation speed drops to a set value, it stops smoothly at a second deceleration lower than the first deceleration to suppress the stopping impact of the turntable. After completing step S1 and the first motor stops, a preset delay time is waited for the residual vibration of the turntable to be attenuated by the elastic damping element before executing steps S2 and S3.

5. The coarse and fine integrated pointing mechanism for optical communication as described in claim 4, characterized in that, The mirror support frame is provided with a pair of second mounting ends, which are rotatably located at both ends of the mounting component in the same direction via a pair of first precision bearings with high axial and radial rigidity. The second motor is a frameless torque motor. The rotor of the second motor is fixedly mounted on one of the second mounting ends and located within the support span formed by a pair of first precision bearings. The stator of the second motor is fixedly mounted on the mounting component so that the stator of the second motor directly drives the rotor of the second motor, thereby driving the reflector support frame to rotate around the pitch axis x2. The reflector is provided with a pair of third mounting ends, which are coaxial and connected by a line passing through the center of the reflector. The pair of third mounting ends are rotatably mounted on the reflector support frame by a pair of second precision bearings.

6. The coarse and fine integrated pointing mechanism for optical communication as described in claim 2, characterized in that, Also includes: The first limit switch is set at the extreme position of the rotation path of the reflector support frame; The second limit switch is set at the extreme position of the rotation path of the reflector; The normally closed contacts of the first and second limit switches are connected in series to the drive power circuits of the second and third motors. When any limit switch is triggered, the drive power of the corresponding motor is physically cut off.

7. The coarse and fine integrated pointing mechanism for optical communication as described in claim 5, characterized in that, It also includes a main conductive slip ring, the rotor end of which is coaxially fixed with the turntable and rotates with it, and the stator end is fixed with the base. The power supply and signal transmission cables of the second motor, the third motor, the first angle sensor, the second angle sensor, the third angle sensor and the beam position detector are connected to the external controller and power supply via the main conductive slip ring. At least one third mounting end of the reflector is a hollow shaft structure, and a miniature conductive slip ring is coaxially disposed inside the hollow shaft structure; the rotor of the miniature conductive slip ring is fixedly connected to the third mounting end and rotates with the reflector, and the stator is fixedly connected to the reflector support frame; the power supply and signal transmission cables of the third motor and the third angle sensor are connected to the rotor end of the main conductive slip ring via the miniature conductive slip ring.

8. The coarse and fine integrated pointing mechanism for optical communication as described in claim 2, characterized in that, It also includes an acceleration sensor, which is mounted on the reflector or the reflector support frame, for detecting high-frequency vibrations of the reflector, and the acceleration sensor is communicatively connected to the controller; The controller also has a pre-stored disturbance propagation model, which was obtained through experimental identification. This disturbance propagation model describes the dynamic relationship between the acceleration sensor signal and the angle disturbance of the reflector. The controller also executes the following control flow: C1. The controller acquires the vibration signal detected by the acceleration sensor in real time; C2. The controller, based on the disturbance transmission model, calculates the predicted mirror angle disturbance component in real time from the vibration signal; C3. The controller uses the inverse vector of the predicted disturbance component as a feedforward compensation command, and fuses it with the fine tracking command based on the beam position detector and the thermal error compensation command based on the thermal deformation compensation model to jointly drive the second motor and the third motor.

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