A vehicle-mounted wireless optical communication terminal and method based on an electric two-dimensional turntable

Abstract

The present invention provides a vehicle-mounted wireless optical communication terminal and method based on an electric two-dimensional turntable. The system is based on the IM / DD communication system and includes an input optical path, an output optical path, a main control unit, an electric two-dimensional turntable, and a display unit. The main control unit is used for communication data processing, controlling the attitude adjustment of the electric two-dimensional turntable, and tracking the beacon light spot. When the main control unit controls the electric two-dimensional turntable to perform attitude adjustment, it first predicts the position of the light spot at the next moment, and then drives the electric two-dimensional turntable to adjust its attitude in advance. Then, according to the actual centroid coordinates of the light spot calculated within the tracking window at this moment, and based on the incremental PID control algorithm, the attitude of the electric two-dimensional turntable is adjusted to move the beacon light spot to the center position of the tracking window. The beacon laser is parallel to the communication laser, and its transmitting unit and receiving unit are both installed on the electric two-dimensional turntable and connected to the main control unit. The present invention has a simple composition, selects general and mature devices, and is convenient for use and maintenance in vehicle-mounted communication scenarios.

Description

Technical Field

[0001] The present invention relates to a laser communication terminal for vehicle-mounted application scenarios, and particularly to a vehicle-mounted wireless optical communication terminal and method based on an electric two-dimensional turntable. Background Art

[0002] In today's society, with the rapid development of technology, the degree of informatization in various industries is constantly improving. In people's various daily production and business activities, a large amount of rich-type data will be generated, such as images, videos, audios, etc. To share these information data in real time and securely, higher requirements will inevitably be put forward for communication technologies. Although radio frequency communication technology can meet data transmission in most scenarios, it is easily affected by external electromagnetic interference, and its communication rate is gradually approaching the Shannon limit, making it difficult to meet the growing communication performance requirements.

[0003] In certain specific application scenarios, when transmitting information data between carriers, its confidentiality, rate, and accuracy are crucial. Due to the advantages of high data transmission rate, good confidentiality, strong anti-interference ability, etc., wireless optical communication technology has received extensive attention from many domestic and foreign research teams, and the technology has developed rapidly. Classic wireless optical communication terminals generally use a coarse-fine two-stage acquisition and tracking mechanism. This design focuses more on performance such as large-airspace scanning and high-precision tracking. However, due to its large volume and complex internal opto-mechanical structure, it limits the usage scenarios to a certain extent. Especially for vehicles, lightweight and small communication terminals are often required for rapid deployment and use.

[0004] In the case of long distances and multiple interferences, usually to minimize the communication bit error rate, wireless optical communication terminals generally compress the beam divergence angle of the communication laser to the diffraction limit level and increase the transmission power at the same time to achieve better communication quality. However, if an extremely narrow communication beam is used to scan a large range of uncertain areas, this will greatly reduce the efficiency of establishing a laser communication link. Therefore, for actual wireless optical communication terminals, beacon lasers with a larger beam divergence angle are usually used to assist in acquisition and tracking, and to maintain the alignment of the visual axes of both ends.

[0005] Therefore, it is of great research value to design a wireless optical communication terminal with a simple structure and a light weight for vehicle-mounted application scenarios. Summary of the Invention

[0006] To solve the above technical problems, the present invention proposes a vehicle-mounted wireless optical communication terminal and method based on an electric two-dimensional turntable. The overall system structure is simple, lightweight, and small, facilitating rapid vehicle mounting, use, and maintenance.

[0007] The technical solution for achieving the object of the present invention is as follows:

[0008] A vehicle-mounted wireless optical communication terminal based on an electric two-dimensional turntable mainly includes an input optical path, an output optical path, a main control unit, an electric two-dimensional turntable, and a display unit. Among them,

[0009] The output optical path includes a beacon laser emission unit and a communication laser emission unit. The beacon laser emission unit is used to emit beacon laser with a wavelength of 790 nm to the other vehicle. The communication laser emission unit is used to emit communication laser, and the communication laser is kept parallel to the optical axis of the 790-nm wavelength beacon laser and is emitted to the other vehicle to transmit information data;

[0010] The input optical path includes a beacon laser reception unit and a communication laser reception unit. The beacon laser reception unit is used to capture the beacon laser emitted by the beacon laser emission unit of the other vehicle, convert the optical signal into an electrical signal, and send it to the main control unit; the communication laser reception unit is used to receive the communication laser emitted by the communication laser emission unit of the other vehicle, convert the optical signal carrying information data into an electrical signal, restore the baseband signal by a demodulator, and then transmit it to the main control unit for subsequent information processing;

[0011] The main control unit is used for data processing, controlling the attitude adjustment of the electric two-dimensional turntable, and tracking the beacon light spot; when the main control unit controls the electric two-dimensional turntable to adjust the attitude in real time, based on the proposed prediction tracking method, it first calculates the possible position of the beacon light spot at the next moment, and sends a posture adjustment instruction to the electric two-dimensional turntable to drive it to adjust the attitude in advance. Then, according to the actual beacon light spot centroid coordinate data calculated within the tracking window of the capture and tracking detector at this moment, through the incremental PID control algorithm, it continues to drive the two-dimensional turntable to adjust the attitude so that the beacon light spot received by the detector moves to the center position of the tracking window;

[0012] The input optical path and the output optical path are both installed on the electric two-dimensional turntable. The electric two-dimensional turntable is connected to the main control unit and performs real-time posture adjustment by controlling the turntable so that the beacon light spot is always at the center position of the tracking window, thereby realizing precise alignment of the laser optical axes of the communication parties;

[0013] The display unit is mainly used to display the capture and real-time tracking effect of the beacon laser of the other vehicle;

[0014] When the beacon light spots within the field of view of the capture and tracking detectors of both vehicles can be stably maintained at the center position of the tracking window, the communication laser emission unit emits the communication laser with the signal modulation completed to the other vehicle, and starts data transmission.

[0015] Further, the beacon laser emission unit includes a 790nm beacon laser, a first collimating mirror, and a first beam splitter. The beacon light emitted by the 790nm beacon laser passes through the first collimating mirror, and then, under the reflection of the first beam splitter, the beacon laser with a wavelength of 790nm is emitted towards the other vehicle.

[0016] Further, the communication laser emission unit includes an 808nm communication laser, a modulator, a data source, and a second collimating mirror. The 808nm wavelength communication laser emitted by the 808nm communication laser serves as an optical carrier. After passing through the modulator, the encoded data source signal is loaded onto the optical carrier. Under the collimation of the second collimating mirror, the divergence angle of the communication laser beam is compressed to the micro-radian level, and then it passes through the first beam splitter, keeping the optical axis parallel to the 790nm wavelength beacon laser and being emitted towards the other vehicle to transmit information data.

[0017] Further, the beacon laser reception unit includes a second beam splitter, a first focusing lens, a first narrowband filter, and a capture and tracking detector. The beacon laser in the parallel light emitted by the other vehicle passes through the second beam splitter and is focused by the first focusing lens under its transmission. Then, the first narrowband filter filters out the background light, and finally, it is received by the capture and tracking detector, which converts the optical signal into an electrical signal and sends it to the main control unit.

[0018] Further, the communication laser reception unit includes a second focusing lens, a second narrowband filter, a communication laser detector, and a demodulator. The communication laser in the parallel light emitted by the other vehicle, under the reflection of the second beam splitter, passes through the second focusing lens. The focused communication laser is filtered out of the background light by the second narrowband filter, and then reaches the communication laser detector, which converts the communication optical signal carrying information data into an electrical signal and restores the baseband signal through the demodulator, and finally transmits it to the main control unit.

[0019] Further, a tracking window with a size of 30×30 pixels is set within the field of view of the capture and tracking detector, and the centroid coordinate data of the light spot is calculated through the image centroid tracking algorithm to automatically track the beacon light spot.

[0020] Further, predicting the possible position of the light spot at the next moment and sending an instruction to the electric two-dimensional turntable to perform attitude adjustment in advance specifically includes:

[0021] Based on the actual centroid coordinate data (x i , y i ) of the light spot calculated at the previous N moments, predicting the coordinate position of the light spot at the next moment as:

[0022]

[0023]

[0024] Among them, N represents the length of consecutive sampling moments, (Δx i , Δy i ) is the estimated deviation of the centroid coordinate value of the beacon light spot at the i-th moment, is the predicted position coordinate of the beacon light spot at the i-th moment.

[0025] Based on the predicted coordinate position of the beacon light spot at the next moment, the main control unit sends a control instruction to the electric two-dimensional turntable to make it perform attitude adjustment in advance. When the system beacon laser receiving unit receives the beacon laser at this moment and calculates the actual centroid coordinate data of the light spot, it then drives the turntable to continue adjusting its attitude through the incremental PID control algorithm.

[0026] Furthermore, when predicting the light spot position at the next moment, the sliding window method is used to process the data, and the main control unit stores the actual centroid coordinate data of the light spot at each moment with a length of N and the predicted value at the current moment.

[0027] Furthermore, the incremental PID control algorithm is as follows:

[0028]

[0029] Among them, k p , k i and k d are the proportional, integral, and differential parameters of the controller respectively; err(k) represents the error signal at the k-th moment, T s is the sampling time of the position sensor, and u(k) is the output control quantity of the discretized PID controller, that is

[0030] A communication method based on the vehicle-mounted wireless optical communication terminal includes the steps of:

[0031] Both vehicles emit beacon lasers to each other through the output optical paths respectively;

[0032] Both vehicles capture the beacon lasers emitted by each other through the input optical paths respectively;

[0033] Based on the beacon lasers captured by the acquisition and tracking detector, the main control unit controls the electric two-dimensional turntable to perform attitude adjustment and track the beacon light spot. When the beacon light spots tracked by the detectors of both vehicles can be stably located at the center position of the tracking window, it indicates that the laser communication link between the two vehicles is successfully established and in good condition. Then, the communication laser emitting unit emits communication lasers carrying information data to the other vehicle, and starts data transmission. During the communication process, the main control unit calculates and controls the two-dimensional turntable to adjust its attitude in real time so that the laser optical axes of the communication parties are accurately aligned, thereby ensuring high communication quality.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention uses an electric two-dimensional turntable to construct a primary capture and tracking mechanism, realizing the light miniaturization of the entire opto-mechanical structure. Moreover, general and mature models are selected for system components, facilitating rapid installation, use, and maintenance in the vehicle-mounted communication application scenario. The present invention uses beacon laser-assisted capture and tracking technology to quickly establish a communication link, and based on the predictive tracking algorithm, it realizes stable and high-precision tracking of the beacon light, ensuring the accurate alignment of the laser visual axes of both communication parties and maintaining a good link state, thereby obtaining a high communication quality. Description of the Drawings

[0035] Figure 1 It is a design scheme for a vehicle-mounted wireless optical communication terminal.

[0036] Figure 2 It is a flowchart of the operation of a vehicle-mounted wireless optical communication terminal.

[0037] Figure 3 It is a schematic diagram of the predictive tracking algorithm. Detailed Embodiments

[0038] In the following, exemplary embodiments of the present application will be described in conjunction with the accompanying drawings. For clarity and conciseness, not all features of the actual embodiments are described in the specification. However, it should be understood that in the process of developing any such actual embodiment, many embodiment-specific decisions may be made to achieve the specific goals of the developer, and these decisions may vary with different embodiments.

[0039] Combined with Figure 1 , a vehicle-mounted wireless optical communication terminal designed by the present invention mainly includes an input optical path, an output optical path, a main control unit, an electric two-dimensional turntable, a display unit, etc. Among them,

[0040] The output optical path mainly includes a beacon laser emission unit and a communication laser emission unit. The beacon laser emission unit includes a 790nm beacon laser, a first collimating mirror 1, and a first beam splitter 1. That is, the beacon laser emits a 790nm wavelength beacon light, which first passes through the first collimating mirror 1 to compress its beam divergence angle to reduce the optical power loss during propagation, and then under the reflection of the first beam splitter 1, it is emitted towards the other vehicle. The communication laser emission unit includes an 808nm communication laser, a modulator, a second collimating mirror 2, and a data source module. The 808nm wavelength communication laser emitted by the communication laser serves as an optical carrier. The modulator loads the encoded data source signal onto the optical carrier, and under the collimation of the second collimating mirror 2, the beam divergence angle of the modulated communication laser is compressed to the micro-radian level, and then it passes through the first beam splitter 1 and is emitted towards the other vehicle while keeping the optical axis parallel to the 790nm wavelength beacon light, thereby transmitting information data.

[0041] The input optical path mainly consists of a beacon laser receiving unit and a communication laser receiving unit. The beacon laser receiving unit includes a second beam splitter 2, a first focusing lens 1, a first narrowband filter 1, and a capture and tracking detector. That is, the parallel light composed of the beacon laser and the communication laser emitted by the other vehicle, when passing through the second beam splitter 2, under its transmission effect, the beacon laser is focused by the first focusing lens 1, then the background light is filtered by the first narrowband filter 1, and finally is received by the field of view of the capture and tracking detector for photoelectric conversion. When the capture and tracking detector successfully captures the beacon laser of the other vehicle, the main control unit controls the electric two-dimensional turntable to automatically adjust its attitude, moves the beacon light spot into the set tracking window, then starts the tracking program, and at the same time dynamically displays the capture and real-time tracking process of the beacon light spot on the image display. The communication laser receiving unit includes a second focusing lens 2, a second narrowband filter 2, a communication laser detector, and a demodulator. The communication laser in the parallel light emitted by the other vehicle, under the reflection effect of the second beam splitter 2, passes through the second focusing lens 2, then the background light is filtered by the second narrowband filter 2, and finally reaches the communication laser detector, converts the communication optical signal carrying information data into an electrical signal, and under the demodulation function of the signal demodulator, restores the baseband signal from it and transmits it to the main control unit for subsequent information processing work. The reflectivity and transmittance of the first and second beam splitters are both above 90%.

[0042] When capturing the beacon laser emitted by the staring of the other vehicle, the capture and tracking detector first performs full-pixel and low-frame-rate detection to achieve large-field-of-view capture. Once a beacon light spot appears within the capture field of view, it indicates that the single-end capture work is completed, and the main control unit will issue an instruction to adjust the attitude angle of the electric two-dimensional turntable to guide the beacon light spot to the center of the capture field of view. Then, the beacon laser of its own side is emitted to the other vehicle. When the capture field of view of the other vehicle's capture and tracking detector successfully captures this beacon light spot, the double-end capture is completed. At this time, both sides' capture and tracking detectors adopt the local area window reading technology, that is, by reducing the field-of-view pixels to increase the frame rate, so as to achieve high-precision dynamic tracking in a small field-of-view range. A tracking window is set within the field of view of the capture and tracking detector, with a size of m×n, and the center position of the window coincides with the capture field of view, and the coordinates are (0,0). When the captured beacon light spot is guided to the tracking window, the gray value H in this area will be significantly greater than the detection threshold H0. At this time, the image centroid tracking algorithm is immediately started to automatically track the beacon light spot. The image centroid tracking algorithm is as follows

[0043]

[0044] Among them,

[0045]

[0046] Wherein, x and y respectively represent the horizontal and vertical coordinates of the pixels in the tracking window; m and n are respectively the number of pixel points on the x-axis and y-axis of the tracking window; h(x, y) is the gray value at the pixel plane (x, y); h t is a preset gray threshold, generally set to 200; (x p , y p ) is the centroid coordinate of the beacon light spot.

[0047] To enable the vehicle-mounted wireless optical communication terminal to achieve more stable and fast tracking, the possible position of the light spot at the next moment can be predicted according to the actual centroid coordinate data of the light spot calculated at each moment, and then the actuator can be driven to operate in advance to adjust the pose state of the opto-mechanical system. Then, wait for the acquisition and tracking detector to sample and receive the beacon laser at the next moment, and realize automatic deviation correction in the closed-loop negative feedback control system. The prediction tracking algorithm is described as follows

[0048] Assume that at a certain N consecutive sampling moments, the predicted values and actual calculated values of the centroid coordinates of the beacon light spot in the tracking window are respectively and (x i , y i ), and the estimated deviation of the coordinate value at each moment is (Δx i , Δy i ), then the calculation method of the predicted value of the centroid coordinate at the next moment is defined as follows

[0049]

[0050]

[0051] Among them, the estimated deviation of the centroid of the light spot can be written as

[0052]

[0053] According to the prediction tracking algorithm, the centroid coordinate position of the beacon light spot at the i + 1 moment is predicted, and the actuator adjusts the pose state in advance. Then, based on the centroid coordinate of the beacon light spot actually received and calculated at the i + 1 moment, the acquisition and tracking detector drives the actuator to continue to adjust the attitude on the basis of the predicted position, so as to compensate for the "prediction - actual" position deviation, and store the deviation signal at the i moment. To avoid a large amount of data storage and reduce the process calculation complexity, a sliding window method is used to process the data, combined with Figure 3, that is, when predicting the centroid coordinates of the beacon light spot at the (i + 2)-th moment, the data at the (i - N + 1)-th moment is removed, and at the same time, the window slides backward by one data position, using the actual centroid coordinate value, predicted coordinate value, and estimated deviation data at the (i + 1)-th moment. Therefore, the main control unit only needs to store the actual centroid coordinate data at each moment with a length of N and the predicted value at the current moment to predict the coordinate position at the next moment. Therefore, this algorithm can also be deployed for an embedded main control chip with limited storage resources and low computing power.

[0054] According to the image centroid tracking algorithm, the centroid coordinates of the beacon light spot at each moment can be calculated. Although various interference factors in the external environment cause the centroid coordinate values to change randomly, for the convenience of representation here, it may be regarded as a variable regarding the image frame number k of the capture and tracking detector. Thus, the distances of the light spot centroid from the center position of the tracking window in two coordinate directions at the k-th moment can be defined as |x p (k)| and |y p (k)|, and the center offset distance

[0055]

[0056] The classic PID controller has the advantages of simple algorithm, strong robustness, and stability and reliability, and is widely used in the industrial control field. The control algorithm is as follows

[0057]

[0058] Among them, e(t) is the error at the t-th moment; T i and T d respectively represent the integral time and differential time of the controller; k p 、k i and k d are the proportional, integral, and differential parameters of the controller respectively. For the convenience of computer programming implementation, the PID controller is discretized, that is, there is

[0059]

[0060] Among them, err(k) represents the error signal at the k-th moment; T s is the sampling time.

[0061] The vehicle-mounted wireless optical communication terminal designed in the present invention uses an electric two-dimensional turntable as the actuator. The scanning range in the azimuth direction is 360°, and in the pitch direction is ±15°. The pitch angle and azimuth angle drive motors of the turntable are both stepper motors. Based on the calculation results of the image automatic tracking algorithm, the main control unit uses the incremental PID control algorithm to control the turntable to adjust its attitude in real time, so as to achieve stable tracking of the beacon light spot. According to the discrete PID control algorithm, the control amount at the (k - 1)-th moment can be obtained as

[0062]

[0063] Then the incremental PID control algorithm is expressed as follows

[0064]

[0065] According to the actual situation, the controller parameters are tuned so that at the moment when the beacon spot tracking program starts, the overshoot δ of the system ≤ 5%, that is, it is ensured that the spot will not jitter significantly due to excessive overshoot or even break away from the tracking window and cause loss of lock. And when the system enters the stable state, the steady-state error σ ≤ 1% to ensure high-precision tracking. Since the communication laser optical axis is parallel to the beacon laser tracking optical axis, while maintaining the alignment state of the beacon light, the communication subsystems of both vehicles emit communication lasers to each other to start the information transmission task until the data transmission is completed.

[0066] Combined with Figure 2 , the communication method of the vehicle-mounted wireless optical communication terminal of the present invention includes:

[0067] During the process of multi-vehicle collaborative work and joint execution of tasks, a large amount of information data will be generated. In application scenarios with high requirements for communication confidentiality, to safely and quickly transmit these data, certain requirements must be placed on the operating mechanism of the vehicle-mounted wireless optical communication terminal. The beacon laser emitted by the 790nm beacon laser is collimated by the first collimating mirror 1, and its beam divergence angle will be compressed to the milliradian level. At the same time, it is also to reduce the energy loss of the laser during transmission and improve the capture probability at the receiving end. The collimated beacon laser is reflected by the first beam splitter 1 and emitted towards its own vehicle, and maintains a staring emission state.

[0068] For the receiving vehicle, the beacon light emitted by the other vehicle passes through the second beam splitter 2 and reaches the first focusing lens 1, then is focused, and various stray light interferences are filtered out by the first narrowband filter 1, and finally enters the acquisition and tracking detector for optoelectronic signal conversion. In particular, when capturing the beacon laser, the acquisition and tracking detector starts to scan the uncertain area in a raster manner under the combined movement of the electric two-dimensional turntable. At this time, the detector capture field of view is set to a full-pixel large field of view, but due to limited computing performance, its frame rate is relatively low. If the beacon laser emitted by the other vehicle is not captured within one scanning cycle, the pose state of its own vehicle needs to be adjusted and a new cycle of scanning is started. At the same time, the detector transmits each frame of image to the main control unit, and the corresponding image processing algorithm calculates the image gray value, and the display real-time displays each frame of image collected by the detector capture field of view for the vehicle operator to view in time.

[0069] Once a beacon light spot appears within the captured field of view, the gray values of the images captured in real time by the detector will change significantly due to the high energy of the light spot. That is, the total gray value calculated by the main control unit will be greater than the preset gray threshold, indicating that the beacon light of the other party has been successfully captured, achieving single-end capture. At this time, the main control unit issues an instruction to the actuator, and the capture and tracking detector stops scanning. Then, the electric two-dimensional turntable automatically adjusts its own pose according to the gradient direction of the image gray value, guiding the beacon light spot within the captured field of view into the tracking window. At this time, the frame rate is increased by reducing the field-of-view pixels. The image processing algorithm calculates the centroid coordinate value of the light spot image within the tracking window in real time, and then predicts the light spot coordinates at the next moment based on this coordinate value, and continues to adjust the electric two-dimensional turntable to make the light spot reach the center of the tracking window. If it is always impossible to move it to the central area, it is necessary to manually check the working state of the two-dimensional turntable and recalibrate the zero position if necessary.

[0070] When the offset distance of the centroid of the light spot within the window is less than the set value, the light spot tracking program is immediately started. The deviation signal between the centroid coordinates calculated at each moment and the center of the window is the input signal of the PID controller. At this time, under the action of the closed-loop negative feedback control system, the electric two-dimensional turntable automatically adjusts its attitude to maintain stable tracking of the beacon light spot. Then, the main control unit turns on its own beacon laser and emits beacon laser to the other vehicle. When the beacon laser receiving unit of the other vehicle successfully captures the beam of beacon light and enters the tracking state, double-end capture and tracking are achieved. At this time, the laser communication link between the two vehicles is successfully established and the optical axes are precisely aligned.

[0071] The process of beacon laser capture and tracking provides a stable link condition for information data transmission between two vehicles. And the communication optical axis is strictly parallel to the beacon optical axis. After various types of data at the information source are encoded, the modulator loads the encoded signal onto the optical carrier. The second collimator 2 compresses the divergence angle of the laser beam to the near diffraction limit angle, and then uses the transmission function of the first beam splitter 1 to emit it to the other vehicle. For the communication laser receiving end, under the reflection of the second beam splitter 2, the communication laser passes through the second focusing lens 2. After its focusing effect, various stray light interferences are filtered out by the second narrow-band filter 2, and then it enters the communication laser detector for optoelectronic conversion. The converted electrical signal is used as the input signal of the demodulator, and under its demodulation function, the baseband signal can be restored. The demodulated data is transmitted to the main control unit for the next information processing.

[0072] After the data transmission between the two vehicles is completed, the vehicle-mounted wireless optical communication terminal stops the beacon light spot tracking program, that is, disconnects the laser communication link, and then turns off the communication laser.

[0073] The in-vehicle wireless optical communication terminal designed by the present invention uses the IM / DD communication system. The modulation and demodulation processes of information data are relatively easy to implement, and the components of the communication subsystem are simple, with high communication reliability. The wireless laser communication technology is used to achieve the fast, secure and anti-interference transmission of large-capacity information data between vehicles.

[0074] As described above, the above are only various implementation manners of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A vehicle-mounted wireless optical communication terminal based on an electric two-dimensional turntable, characterized in that, It includes an input optical path, an output optical path, a main control unit, an electric two-dimensional turntable, and a display unit. Among them, the output optical path includes a beacon laser emission unit and a communication laser emission unit. The beacon laser emission unit is used to emit beacon laser with a wavelength of 790 nm towards the other vehicle. The communication laser emission unit is used to emit communication laser, and the communication laser is parallel to the optical axis of the 790-nm wavelength beacon laser, and is emitted towards the other vehicle and transmits information data; the input optical path includes a beacon laser reception unit and a communication laser reception unit. The beacon laser reception unit is used to capture the beacon laser emitted by the beacon laser emission unit of the other vehicle, convert the optical signal into an electrical signal, and then send it to the main control unit; the communication laser reception unit is used to receive the communication laser emitted by the communication laser emission unit of the other vehicle, convert the optical signal carrying data information into an electrical signal, pass through a demodulator, and then transmit it to the main control unit; the main control unit is used for data processing, controlling the attitude adjustment of the electric two-dimensional turntable, and tracking the beacon light spot; based on a prediction algorithm, the main control unit first predicts the possible position of the light spot at the next moment, and sends an instruction to let the electric two-dimensional turntable perform attitude adjustment in advance. Then, according to the actual centroid coordinates of the beacon light spot calculated within the tracking window of the detector at this moment, through an incremental PID control algorithm, the main control unit continues to drive the electric two-dimensional turntable to adjust its attitude so that the beacon light spot moves to the center position of the tracking window; the input optical path and the output optical path are both installed on the electric two-dimensional turntable. The electric two-dimensional turntable is connected to the main control unit, and through the real-time attitude adjustment of the turntable, the beacon light spot is always at the center position of the tracking window; the display unit is used to display the capture and real-time tracking effect of the beacon light spot; When the beacon lasers within the field of view of the capture and tracking detectors of both vehicles can be stably maintained at the desired center position of the tracking window, communication is carried out; predicting the possible position of the light spot at the next moment and sending an instruction to let the electric two-dimensional turntable perform attitude adjustment in advance specifically includes: The actual centroid coordinate data (x i , y i ) of the light spot calculated based on the previous N moments is used to predict the light spot coordinate position at the next moment as follows: where N represents the length of consecutive sampling instants, (Δx i , Δy i ) is the estimated deviation of the centroid coordinate value of the beacon light spot at the i-th instant, is the predicted position coordinate of the beacon light spot at the i-th instant; Based on the predicted position of the centroid of the beacon light spot at the next moment, the main control unit sends an instruction to drive the two-dimensional turntable to adjust its attitude in advance. When the beacon laser reception unit receives the beacon laser at this moment and calculates the actual centroid coordinates of the light spot, the main control unit then controls the turntable to adjust its attitude again through an incremental PID control algorithm; the incremental PID control algorithm is: where k p , k i and k d are the proportional, integral, and derivative parameters of the controller respectively; err(k) represents the error signal at the k-th moment, T s is the sampling time of the position sensor, and u(k) is the output control quantity of the discretized PID controller, that is 2. The vehicle-mounted wireless optical communication terminal based on an electric two-dimensional turntable according to claim 1, wherein the beacon laser emission unit includes a 790-nm beacon laser, a first collimating mirror, and a first beam splitter. The beacon light emitted by the 790-nm beacon laser passes through the first collimating mirror, and then under the reflection of the first beam splitter, the 790-nm wavelength beacon laser is emitted towards the other vehicle.

3. The vehicle-mounted wireless optical communication terminal based on an electric two-dimensional turntable according to claim 2, characterized in that, The communication laser transmitting unit includes an 808nm communication laser, a modulator, a data source, and a second collimator. The 808nm wavelength communication laser emitted by the 808nm communication laser serves as an optical carrier, and the modulator loads the encoded data source signal onto the optical carrier. Under the collimation of the second collimator, the divergence angle of the modulated communication laser beam is compressed to the micro-radian level, and then it passes through the first beam splitter, keeping the optical axis parallel to the 790nm wavelength beacon laser, and is transmitted to the other vehicle to transmit information data.

4. The vehicle-mounted wireless optical communication terminal based on an electric two-dimensional turntable according to claim 1, wherein The beacon laser receiving unit includes a second beam splitter, a first focusing lens, a first narrowband filter, and a acquisition and tracking detector. The beacon laser in the parallel light emitted by the other vehicle passes through the second beam splitter and is focused by the first focusing lens under its transmission effect. Then, the first narrowband filter filters out the background light. Finally, it is received by the acquisition and tracking detector, which converts the optical signal into an electrical signal and sends it to the main control unit.

5. The vehicle-mounted wireless optical communication terminal based on an electric two-dimensional turntable according to claim 4, characterized in that, The communication laser receiving unit includes a second focusing lens, a second narrowband filter, a communication laser detector, and a demodulator. The communication laser in the parallel light emitted by the other vehicle, under the reflection of the second beam splitter, passes through the second focusing lens. The focused communication laser is filtered by the second narrowband filter to remove the background light, and finally reaches the communication laser detector, which converts the communication optical signal carrying information data into an electrical signal, restores the baseband signal through the demodulator, and transmits it to the main control unit.

6. The vehicle-mounted wireless optical communication terminal based on an electric two-dimensional turntable according to claim 1, characterized in that, The acquisition and tracking detector sets a tracking window with a size of 30×30 pixels in its field of view, and calculates the centroid coordinate data of the light spot through the image centroid tracking algorithm to automatically track the beacon light spot.

7. The vehicle-mounted wireless optical communication terminal based on an electric two-dimensional turntable according to claim 1, wherein, When predicting the light spot position at the next moment, the sliding window method is used to process the data. The main control unit stores the actual centroid coordinate data of the light spot at each moment with a length of N and the predicted value at the current moment.

8. A method for an in-vehicle wireless optical communication terminal based on an electric two-dimensional turntable according to any one of claims 1-7, characterized in that, It includes the steps: The two vehicles respectively emit beacon lasers to each other through the output optical paths; The two vehicles respectively capture the beacon lasers emitted by the other party through the input optical paths; Based on the captured beacon lasers, the main control unit controls the electric two-dimensional turntable to adjust the attitude and track the beacon light spot. When the beacon light spots tracked by the detectors of the two vehicles can both stably stay at the center position of the desired tracking window, the laser communication link between the two vehicles is successfully established at this time. Then, communication is carried out through the output optical path and the input optical path. During the communication process, the main control unit controls the turntable to adjust the attitude in real time to keep the laser optical axes of the communication parties accurately aligned.

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