Calibration method of wireless optical communication terminal and communication terminal

Abstract

The invention discloses a calibration method of a wireless optical communication terminal and a communication terminal, and relates to the field of wireless communication or other related technical fields, and the method comprises the steps: controlling a bearing platform to rotate based on a first rotation stepping and a first rotation direction; in the rotating process, a first coarse adjustment position of the bearing platform is determined based on optical power collection data of the second communication terminal, and the first coarse adjustment position is used as a reference position to adjust the camera subsystem so as to reduce coarse parallelism between the optical axis of the camera subsystem and the optical axis of the optical subsystem; and taking the first coarse adjustment position as an initial position, controlling the bearing platform to rotate based on the second rotation stepping and the second rotation direction, determining a boundary deviation value generating a preset error rate, and performing accurate calibration on the optical subsystem and the camera subsystem based on the boundary deviation value so as to enable the optical axis of the camera subsystem to be parallel to the optical axis of the optical subsystem. According to the invention, the technical problem of low stability of a communication link caused by low calibration precision of the communication terminal in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology or other related technical fields, and in particular to a calibration method for a wireless optical communication terminal and a communication terminal. Background Art

[0002] With the booming low-altitude economy, the application scenarios of drone technology are becoming increasingly diverse. From agricultural and forestry plant protection, power inspections, and aerial tours to mapping and aerial filming, drones have become a key tool in driving this emerging economy. In particular, when building low-altitude network communication systems, the demand for relay network connections between drones and real-time high-speed communication between drones and the ground is increasing significantly. This requires not only efficient data transmission capabilities but also the ability to overcome the complex physical obstacles and dynamic interference in the low-altitude environment.

[0003] Communication between drones and between drones and the ground is a key component of the low-altitude economy. Radio frequency (RF) communication technologies, such as 4G / 5G mobile networks, Wi-Fi, and Bluetooth, are primarily used to enable data transmission. These technologies, based on the propagation of electromagnetic waves in free space, can provide relatively stable data links. However, in certain application scenarios, particularly those requiring high data rates and long-distance communication, their performance begins to show limitations, such as the increasing scarcity of spectrum resources and licensing issues, electromagnetic interference, and high communication capacity and costs.

[0004] In related technologies, in order to overcome the drawbacks of radio frequency (RF) communication technology, it is proposed to use free space optical communication (FSO) technology as a communication means in low-altitude communication scenarios. Free space optical communication technology utilizes the propagation of light waves in free space. Compared with RF technology, it is no longer limited by spectrum resources, and under specific conditions, such as a clear atmospheric environment without fog or dust, it can provide higher data transmission rates than RF communication.

[0005] However, FSO technology also faces a series of challenges in drone communication scenarios. The vibration and unstable flight state of drones make it extremely difficult to align and track optical signals. Even in short-distance transmission, it is difficult to ensure stable coupling of light beams, resulting in unstable communication links and poor communication quality.

[0006] To address the above-mentioned problems, no effective solutions have been proposed so far. Summary of the Invention

[0007] The embodiments of the present invention provide a calibration method for a wireless optical communication terminal and a communication terminal, so as to at least solve the technical problem in the related art that the calibration accuracy of the communication terminal is low, thereby resulting in low stability of the communication link.

[0008] According to one aspect of an embodiment of the present invention, a calibration method for a wireless optical communication terminal is provided, which is applied to a first target terminal, wherein a carrier platform is deployed on the first target terminal, and an optical subsystem and a camera subsystem are installed on the carrier platform. The calibration method for the wireless optical communication terminal includes: controlling the rotation of the carrier platform based on a first rotation step and a first rotation direction; in the process of controlling the rotation of the carrier platform based on the first rotation step and the first rotation direction, receiving optical power acquisition data of a second target terminal, determining a first coarse adjustment position of the carrier platform based on the optical power acquisition data, and roughly calibrating the camera subsystem with the first coarse adjustment position as a reference position, so that the optical axis of the camera subsystem is aligned with the first rotation step and the first rotation direction. The degree of optical axis deviation between the optical axes of the optical subsystems is reduced to a preset condition, wherein the second target terminal is a terminal that performs wireless optical communication with the first target terminal; based on the second rotation step and the second rotation direction, the supporting platform is controlled to start rotating on the basis of the first coarse adjustment position; in the process of controlling the supporting platform to rotate based on the second rotation step and the second rotation direction, the boundary offset value that produces a preset bit error rate is determined, and the first fine adjustment position of the supporting platform is determined based on the boundary offset value. Based on the first fine adjustment position, the camera subsystem is precisely calibrated so that the camera optical axis of the camera subsystem is parallel to the optical axes of the receiving lens and the transmitting lens of the optical subsystem.

[0009] Furthermore, the first coarse adjustment position of the carrying platform is determined based on the optical power acquisition data, and the step of roughly calibrating the camera subsystem with the first coarse adjustment position as a reference position includes: determining the spot center of the emitted light beam according to the optical power acquisition data, wherein the optical power acquisition data is acquired by a free-space optical power meter; when the spot center coincides with the center of the receiving lens on the second target terminal, determining that the transmitting lens of the first target terminal and the receiving lens of the second target terminal are coaxial, and obtaining the first coarse adjustment position of the carrying platform; with the first coarse adjustment position as a reference position, obtaining the imaging position of the target recognition target image in the camera subsystem; adjusting the imaging position of the target recognition target image to the pixel center of the camera subsystem to complete the coarse calibration of the camera subsystem.

[0010] Furthermore, the step of determining the spot center of the emitted light beam based on the optical power acquisition data includes: determining the position where the optical power value corresponding to the emitted light beam is the largest through the optical power acquisition data, and taking the position where the optical power value is the largest as the spot center of the emitted light beam, wherein, after determining the spot center, the first rotation direction of the carrier platform for the next rotation process is updated according to the relative position of the spot center and the center of the receiving lens on the second target terminal, and the next rotation process is performed based on the updated first rotation direction.

[0011] Furthermore, after determining the spot center of the emitted light beam according to the optical power acquisition data, it also includes: taking the center of the receiving lens as a reference point, determining the periphery of the spot of the emitted light beam based on a preset optical power attenuation value; obtaining the size of the periphery of the spot to obtain spot periphery size data; and verifying whether the center of the spot coincides with the center of the receiving lens based on the spot periphery size data.

[0012] Furthermore, the second rotation direction at least includes: a first direction on a horizontal plane, a second direction on the horizontal plane, the first direction is opposite to the second direction, and in the process of controlling the rotation of the carrying platform, the step of determining the boundary offset value for generating a preset bit error rate includes: step one, taking the first coarse adjustment position as the initial position, controlling the carrying platform to rotate in the first direction on the basis of the initial position until the light signal received in the receiving lens generates the preset bit error rate, and recording the first offset value when the preset bit error rate is generated, wherein the first direction is a direction that causes the imaging position of the target recognition target image in the camera subsystem to shift in the opposite direction of the first direction, and the first offset value includes at least one of the following: a first offset step of the carrying platform deviating from the initial position on the horizontal plane, a first pixel center offset value of the target recognition target image deviating from the pixel center; step two Second, control the supporting platform to rotate in a second direction based on the initial position until the light signal received by the receiving lens generates the preset bit error rate, and record the second offset value when the preset bit error rate is generated, wherein the second direction is a direction that causes the imaging position of the target recognition target image in the camera subsystem to translate in the opposite direction of the second direction, and the second offset value includes at least one of the following: a second offset step of the supporting platform from the initial position on the horizontal plane, and a second pixel center offset value of the target recognition target image from the pixel center; step three, calculate the average value of the first offset value and the second offset value to obtain an average level offset value; step four, repeat steps one to three above, perform iterative calculations until the number of iterations reaches a preset number threshold, average the average level offset values obtained from each iterative calculation, and obtain a boundary offset value generated by the preset bit error rate.

[0013] Furthermore, the second rotation direction also includes: a third direction on the vertical plane, a fourth direction on the vertical plane, and the third direction is opposite to the fourth direction. In the process of controlling the rotation of the carrying platform, the step of determining the boundary offset value for generating a preset bit error rate also includes: step one, taking the first coarse adjustment position as the initial position, controlling the carrying platform to rotate in the third direction on the basis of the initial position until the light signal received by the receiving lens generates the preset bit error rate, and recording the third offset value when the preset bit error rate is generated, wherein the third direction is a direction that causes the imaging position of the target recognition target image in the camera subsystem to shift in the opposite direction of the three directions, and the third offset value includes at least one of the following: a third offset step of the carrying platform from the initial position on the vertical plane, and a third pixel center offset value of the target recognition target image from the pixel center; step two, Control the supporting platform to rotate in a fourth direction based on the initial position until the light signal received by the receiving lens generates the preset bit error rate, and record the fourth offset value when the preset bit error rate is generated, wherein the fourth direction is a direction that causes the imaging position of the target recognition target image in the camera subsystem to translate in the opposite direction of the fourth direction, and the fourth offset value includes at least one of the following: a fourth offset step of the supporting platform from the initial position in the vertical plane, and a fourth pixel center offset value of the target recognition target image from the pixel center; step three, calculate the average value of the third offset value and the fourth offset value to obtain an average vertical offset value; step four, repeat steps one to three above, perform iterative calculations until the number of iterations reaches a preset number threshold, average the average vertical offset values obtained from each iterative calculation, and obtain a boundary offset value generated by the preset bit error rate.

[0014] Furthermore, the first fine-tuning position of the carrier platform is determined based on the boundary offset value, and the step of accurately calibrating the camera subsystem based on the first fine-tuning position includes: controlling the carrier platform to rotate in the direction indicated by the boundary offset value to obtain the first fine-tuning position of the carrier platform; obtaining the imaging offset position of the target recognition target image in the camera subsystem on the carrier platform at the first fine-tuning position; adjusting the angle of the camera subsystem based on the imaging offset position, and monitoring the imaging position of the target recognition target image during the adjustment process until the imaging position of the target recognition target image coincides with the pixel center of the camera subsystem, thereby completing the accurate calibration of the camera subsystem.According to another aspect of an embodiment of the present invention, another calibration method for a wireless optical communication terminal is provided, which is applied to a second target terminal, wherein a carrying platform is deployed on the second target terminal, and an optical subsystem and a camera subsystem are installed on the carrying platform. The calibration method for the wireless optical communication terminal includes: receiving a data acquisition request sent by a first target terminal, and based on the data acquisition request, collecting optical power data received by the second target terminal through a free space optical power meter to obtain optical power acquisition data of the second target terminal, wherein the first target terminal is a terminal that performs wireless optical communication with the second target terminal; returning the optical power acquisition data of the second target terminal to the first target terminal; upon receiving a rough calibration result of the first target terminal, controlling the rotation of the carrying platform based on a first rotation step and a first rotation direction, receiving the optical power acquisition data of the first target terminal in the process of controlling the rotation of the carrying platform based on the first rotation step and the first rotation direction, determining a second coarse adjustment position of the carrying platform based on the optical power acquisition data of the first target terminal, and adjusting the camera subsystem based on the second coarse adjustment position. The subsystem is roughly calibrated so that the degree of optical axis deviation between the optical axis of the camera subsystem and the optical axis of the optical subsystem is reduced to a preset condition, wherein the second target terminal is a terminal that performs wireless optical communication with the first target terminal, and wherein the optical power acquisition data of the first target terminal is acquired when the carrying platform on the first target terminal is in a first coarse adjustment position; when the first target terminal completes the precise calibration, the carrying platform is controlled to rotate on the basis of the second coarse adjustment position based on the second rotation step and the second rotation direction, and in the process of controlling the carrying platform to rotate based on the second rotation step and the second rotation direction, a boundary offset value for generating a preset bit error rate is determined, and a second fine adjustment position of the carrying platform is determined based on the boundary offset value, and the camera subsystem is precisely calibrated on the basis of the second fine adjustment position so that the camera optical axis of the camera subsystem is parallel to the optical axes of the receiving lens and the transmitting lens of the optical subsystem, wherein the boundary offset value is determined based on the optical signal emitted when the carrying platform on the first target terminal is in the first fine adjustment position.

[0015] According to another aspect of an embodiment of the present invention, a target terminal is also provided, including: an optical subsystem, including a receiving lens and a transmitting lens, for receiving light signals and transmitting light signals; a camera subsystem, including a camera, and the camera subsystem is used for image recognition; a carrying platform, for fixing the optical subsystem and the camera subsystem; wherein, the target terminal includes a first target terminal or a second target terminal, the first target terminal executes any one of the above-mentioned calibration methods of the wireless optical communication terminal applied to the first target terminal, and the second target terminal executes the above-mentioned calibration method of the wireless optical communication terminal applied to the second target terminal.

[0016] Furthermore, the camera subsystem also includes: a micro-angle adjustment module, including multiple precision thread pairs and a top ball, for adjusting the angle of the camera subsystem so that the optical axis of the receiving lens and the optical axis of the transmitting lens of the optical subsystem are parallel to the camera optical axis of the camera subsystem.

[0017] In the present application, the following steps are performed: controlling the rotation of the carrying platform based on a first rotation step and a first rotation direction, and receiving optical power acquisition data of the second target terminal in the process of controlling the carrying platform to rotate based on the first rotation step and the first rotation direction, determining a first coarse adjustment position of the carrying platform based on the optical power acquisition data, and roughly calibrating the camera subsystem with the first coarse adjustment position as a reference position so that the degree of optical axis deviation between the optical axis of the camera subsystem and the optical axis of the optical subsystem is reduced to a preset condition, wherein the second target terminal is a terminal that performs wireless optical communication with the first target terminal, and then controlling the carrying platform to start rotating on the basis of the first coarse adjustment position based on the second rotation step and the second rotation direction, and finally determining a boundary offset value that generates a preset bit error rate in the process of controlling the carrying platform to rotate based on the second rotation step and the second rotation direction, determining a first fine adjustment position of the carrying platform based on the boundary offset value, and accurately calibrating the camera subsystem based on the first fine adjustment position so that the camera optical axis of the camera subsystem is parallel to the optical axes of the receiving lens and the transmitting lens of the optical subsystem.

[0018] In this application, a two-stage calibration process is used to first achieve preliminary alignment between the optical subsystem and the camera subsystem to ensure that the optical signal can be transmitted to the signal receiving end. Then, a more refined calibration is performed by finding the boundary offset value that produces a preset bit error rate, further improving the alignment accuracy and reducing the bit error rate during communication. This achieves high-precision optical axis alignment between the drone and the ground wireless optical communication terminal, reducing optical loss and signal interference during transmission. Through the two stages of coarse adjustment and fine adjustment, the technical effect of improving the calibration accuracy of the communication terminal is achieved, thereby ensuring that the camera optical axis is parallel to the optical axis of the transmitting and receiving lenses of the optical subsystem, optimizing the coupling efficiency of the optical communication link, and improving the stability of the communication and the data transmission rate. This solves the technical problem in the related art that the calibration accuracy of the communication terminal is low, resulting in low stability of the communication link. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 is a flow chart of an optional calibration method for a wireless optical communication terminal according to an embodiment of the present invention;

[0021] Figure 2 is a flowchart of another optional calibration method for a wireless optical communication terminal according to an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of an optional target terminal according to an embodiment of the present invention;

[0023] Figure 4 is a schematic diagram of an optional optical communication system according to an embodiment of the present invention Figure 1 ;

[0024] Figure 5 is a schematic diagram of an optional optical communication system according to an embodiment of the present invention Figure 2 ;

[0025] Figure 6 is a schematic diagram of an optional camera subsystem according to an embodiment of the present invention Figure 1 ;

[0026] Figure 7 is a schematic diagram of an optional camera subsystem according to an embodiment of the present invention Figure 2 ;

[0027] Figure 8 is a schematic diagram of an optional camera subsystem according to an embodiment of the present invention Figure 3 ;

[0028] Figure 9 1 is a schematic diagram of imaging of an optional target recognition target according to an embodiment of the present invention.

[0029] Reference numerals

[0030] Target recognition target 1, camera subsystem 2, adapter plate 3, optical subsystem 4, camera subsystem display screen 5, center cross 6, target feature recognition circle 7, center recognition circle 8;

[0031] Camera lens 2-1, teleconverter 2-2, camera fixing frame 2-3, camera frame 2-4, long-tongue L-shaped camera bracket 2-5, precision thread pair 2-6, precision thread copper sleeve 2-7, precision top bead 2-8. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0034] To facilitate those skilled in the art to understand the present invention, some of the terms or nouns involved in the embodiments of the present invention are explained below:

[0035] Field-Programmable Gate Array (FPGA) is a semi-custom integrated circuit that can process high-speed optical communication signals in real time, including signal decoding, synchronization, clock recovery and other functions to ensure accurate data reception.

[0036] It should be noted that the calibration method and device of the wireless optical communication terminal in this application can be used in the field of wireless communication technology. When calibrating the wireless optical communication terminal, it can also be used in any field other than the field of wireless communication technology. When calibrating the wireless optical communication terminal, the application field of the calibration method and device of the wireless optical communication terminal in this application is not limited.

[0037] It should be noted that the relevant information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are information and data authorized by the user or fully authorized by all parties, and the collection, storage, use, processing, transmission, provision, disclosure and application of the relevant data comply with the relevant laws, regulations and standards of the relevant regions, take necessary confidentiality measures, do not violate public order and good morals, and provide corresponding operation entrances for users to choose to authorize or refuse. For example, an interface is set up between this system and the relevant users or institutions. Before obtaining relevant information, it is necessary to send an acquisition request to the aforementioned user or institution through the interface, and obtain the relevant information after receiving the consent information fed back by the aforementioned user or institution.

[0038] It should be noted that in this application, when collecting and analyzing customer information, corresponding operation entrances are provided for users to choose to agree or reject the automated decision-making results; if the user chooses to reject, the expert decision-making process will be entered.

[0039] The following embodiments of the present invention can be applied to calibration systems, applications, and devices for various wireless optical communication terminals. This invention achieves a parallel relationship between the camera optical axis and the optical axis of the transmitting lens of the optical subsystem through rough calibration. Based on this rough calibration, the present invention then achieves precise calibration of the communication terminal by finding the boundary that produces a preset bit error rate. This reduces the bit error rate caused by inaccurate optical axis alignment and improves the stability and data transmission quality of the wireless optical communication terminal.

[0040] The present invention will be described in detail below with reference to various embodiments.

[0041] Example 1

[0042] According to an embodiment of the present invention, an embodiment of a calibration method for a wireless optical communication terminal is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0043] The calibration method of the wireless optical communication terminal according to the embodiment of the present invention is applied to a first target terminal. A carrying platform is deployed on the first target terminal, and an optical subsystem and a camera subsystem are installed on the carrying platform.

[0044] In an optional embodiment, the first target terminal can be a UAV terminal or a ground communication terminal. The calibration method of the wireless optical communication terminal of the embodiment of the present invention can be applied to the calibration of a UAV terminal and a ground communication terminal or between UAV terminals, thereby promoting high-speed and reliable communication between UAVs and UAVs, and between UAVs and the ground, especially in scenarios such as low-altitude economy, large-scale UAV networking, and high-density flight, which has important practical value and technical significance.

[0045] Figure 1 FIG. 1 is a flow chart of an optional calibration method for a wireless optical communication terminal according to an embodiment of the present invention. Figure 1 As shown, the method includes the following steps:

[0046] The embodiment of the present invention is divided into two parts: rough calibration and fine calibration. The result of rough calibration is to make the optical axis of the camera and the optical axis of the transmitting lens of the optical subsystem roughly parallel. The result of fine calibration is to make the camera subsystem and the transmitting lens and receiving lens of the optical subsystem parallel.

[0047] Before calibration, the camera subsystem and optical subsystem need to be installed. The optical axes of the optical subsystem, that is, the optical axes of the transmitting lens and the receiving lens, are already coaxial. The camera subsystem and the optical subsystem together constitute the optical communication system of the communication terminal and are fixed on a supporting platform. The supporting platform can be a drone gimbal or a ground turntable that can be rotated in any space to adjust the direction of the optical communication system so that the optical communication systems at both ends can be aligned, thereby ensuring that the optical signal can be accurately transmitted to the receiver, improving the coupling efficiency of the optical signal into the optical fiber, and ensuring communication quality. Enhanced communication stability.

[0048] After the camera subsystem and the optical subsystem are installed, the target recognition target of the opposite communication terminal (i.e., the second target terminal) is searched for by the camera on the camera subsystem. The target recognition target consists of three target feature recognition circular patterns and one center recognition circular pattern. When the pattern captured by the camera contains the above four patterns, the two terminals are roughly aligned. However, at this time, the optical axis of the camera on the first target terminal is not coaxial with the optical axis of the receiving lens and the optical axis of the transmitting terminal on the second target terminal. The light cannot be coupled to the multi-mode light, that is, the optical communication system cannot work. Therefore, the terminal needs to be adjusted so that the camera optical axis is parallel to the optical axis of the receiving lens and the optical axis of the transmitting lens, and is coaxial with the optical axis of the camera, the optical axis of the receiving lens, and the optical axis of the transmitting lens at the other end. This ensures that the optical communication system can accurately receive the optical signal and realize communication between the two communication terminals.

[0049] Step S101 : controlling the rotation of the carrying platform based on a first rotation step and a first rotation direction.

[0050] Before starting the optical axis alignment debugging, first set the first rotation step and the first rotation direction. The first rotation step refers to the angle increment of the platform rotation each time the carrier platform (including but not limited to the gimbal of the drone or the turntable of the ground terminal) is adjusted. It is usually a smaller angle unit, so that the optimal alignment angle can be explored in detail during the coarse adjustment process. The first rotation direction refers to the direction of the initial rotation of the carrier platform. The selection of this direction can help the system find the approximate range of the optical axis alignment more quickly. The initial direction of the first rotation direction is set based on the experience value, and the first rotation direction is constantly changing during the subsequent control of the rotation of the carrier platform.

[0051] The platform is then controlled to rotate according to the set first rotation step and first rotation direction. This control process allows the platform to be driven by a stepper motor, allowing precise rotation adjustment according to the preset first rotation step and first rotation direction. The platform's rotation is intended to change the orientation of the optical subsystem, allowing the transmitting and receiving lenses to attempt to receive or transmit optical signals at different fields of view, thereby finding the optimal alignment angle. When both ends are aligned, the degree of optical axis deviation between the camera subsystem and the optical subsystem on the communication terminal can be determined to facilitate coarse adjustment.

[0052] Step S102: In the process of controlling the carrier platform to rotate based on the first rotation step and the first rotation direction, optical power acquisition data of the second target terminal is received, a first coarse adjustment position of the carrier platform is determined based on the optical power acquisition data, and the camera subsystem is roughly calibrated with the first coarse adjustment position as a reference position, so that the degree of optical axis deviation between the optical axis of the camera subsystem and the optical axis of the optical subsystem is reduced to a preset condition.

[0053] In step S102, while the support platform rotates, optical power data of the optical signal received by the second communication terminal at the opposite end of the first communication terminal is synchronously collected. This optical power data reflects the optical signal received by the optical subsystem at the second target terminal. As the optical axis alignment gradually approaches the optimal state, the optical power value increases until it reaches a maximum value. When the collected optical power value reaches or approaches the maximum value, it indicates that the current optical axis alignment at both ends is relatively ideal. At this time, the support platform's rotation state should be locked, that is, the adjustment of the first rotation step and the first rotation direction should be stopped to maintain the current optical axis alignment.

[0054] The second communication terminal described above is a terminal that conducts wireless optical communication with the first communication terminal. The optical power data is collected using a free-space optical power meter. Since wireless optical communication terminals transmit over long distances, when the optical signal reaches the other end, the light spot area is larger than the receiving lens aperture. Furthermore, near-infrared light cannot be observed with the naked eye, making it impossible to visually inspect the light spot size, position, and distribution. Using a free-space optical power meter to measure the spatial distribution of the light spot can better locate the center of the light spot. Furthermore, due to the large light spot, the aperture of the free-space optical power meter's measurement surface may not be able to fully capture the light spot. Therefore, the location of the light spot center found using the optical power meter is rough, not precise.

[0055] By iteratively rotating the carrying platform and reading the optical power data at the receiving end after each rotation, the center of the light spot is determined by the optical power data. After determining the center of the light spot, the degree of deviation between the camera subsystem and the optical subsystem is obtained through the image of the target recognition target captured in the camera, and the camera subsystem is adjusted to continuously reduce the optical axis deviation between the local camera subsystem and the optical subsystem until the preset condition is reached. The preset condition is that the optical axis of the local camera is roughly parallel to the optical axis of the optical subsystem. Since the center of the light spot is rough, the adjustment of the camera subsystem at this time also belongs to the coarse adjustment stage, so it can only achieve rough parallelism between the optical axis of the camera and the optical subsystem. Precise calibration is required later to complete the coarse adjustment of the camera subsystem and the optical subsystem to obtain the coarse adjustment result.

[0056] It should be noted that the rough calibration method of the first communication terminal and the second communication terminal is the same. After the optical subsystem and camera subsystem of the first communication terminal are roughly calibrated, the first communication terminal is fixed, and the optical subsystem and camera subsystem of the second communication terminal need to be roughly calibrated to ensure that the optical subsystems at both ends can receive light signals normally. The coarse adjustment results may include: coarse adjustment position information of the optical subsystem and the camera subsystem, that is, the direction of the optical subsystem and the camera subsystem.

[0057] Furthermore, the first coarse adjustment position of the carrier platform is determined based on the optical power acquisition data, and the step of roughly calibrating the camera subsystem with the first coarse adjustment position as the reference position includes: determining the spot center of the emitted light beam according to the optical power acquisition data, wherein the optical power acquisition data is acquired by a free space optical power meter; when the spot center coincides with the center of the receiving lens on the second target terminal, determining that the transmitting lens of the first target terminal and the receiving lens of the second target terminal are coaxial, and obtaining the first coarse adjustment position of the carrier platform; with the first coarse adjustment position as the reference position, obtaining the imaging position of the target recognition target image in the camera subsystem; adjusting the imaging position of the target recognition target image to the pixel center of the camera subsystem, and completing the coarse calibration of the camera subsystem.

[0058] Specifically, the steps for executing the rough calibration include controlling the rotation of the carrier platform according to a pre-set first rotation step and a first rotation direction, ensuring that each rotation is precisely controlled and that the optimal alignment angle can be explored in detail. Each time the carrier platform is controlled to rotate an angle, the free-space optical power meter on the second communication terminal (such as a ground receiving station) starts working to collect the optical power data received by the receiving lens. These data reflect the reception status of the optical signal when it is transmitted from the transmitting lens of the first communication terminal (such as a drone) to the receiving lens of the second communication terminal. By looking at the changing trend of the optical power data, it can be determined whether the alignment between the optical subsystems at both ends is close to the ideal state.

[0059] During this iterative rotation process, the optical power data is collected to analyze and determine the center of the transmitted light spot. This is the point where the beam's energy is concentrated and is crucial to the performance of the communication link. When the center of the light spot coincides with the center of the receiving lens on the second communication terminal, the alignment has met the coarse adjustment requirements, indicating that the transmitting lens of the first communication terminal and the receiving lens of the second communication terminal are coaxial. The carrier platform is then fixed, and the alignment status at this point is recorded to obtain the first coarse adjustment position of the carrier platform, which contains the position information of the optical subsystem and camera subsystem in the current alignment state.

[0060] Then, using the first coarse adjustment result as a reference position, the first communication terminal's camera subsystem observes the target recognition target on the second target terminal, and records the position of the target recognition target imaged by the first target terminal's camera. The camera subsystem on the first communication terminal is then adjusted to ensure that the target recognition target image is precisely centered on the camera subsystem's pixel. This step is achieved using a micro-angle adjustment mechanism.

[0061] Furthermore, while adjusting the micro-angle adjustment structure, the center position of the center recognition circle of the target recognition target of the second target terminal is obtained at the imaging position of the camera subsystem, and the positional relationship between the center position of the center recognition circle at the imaging position of the camera subsystem and the pixel center cross of the camera subsystem is determined. If the positional relationship shows that the center position of the center recognition circle at the imaging position of the camera subsystem coincides with the pixel center cross of the camera subsystem, adjustment is stopped. Otherwise, adjustment is continued until the center position of the center recognition circle at the imaging position of the camera subsystem coincides with the pixel center cross of the camera subsystem. This ensures that the optical axis of the camera subsystem is roughly parallel to the optical axis of the optical subsystem, thereby improving the accuracy and efficiency of subsequent fine-tuning.

[0062] Furthermore, the step of determining the spot center of the emitted light beam based on the optical power acquisition data includes: determining the position at which the optical power value corresponding to the emitted light beam is the largest through the optical power acquisition data, and taking the position at which the optical power value is the largest as the spot center of the emitted light beam, wherein, after determining the spot center, the first rotation direction of the carrier platform for the next rotation process is updated according to the relative position between the spot center and the center of the receiving lens on the second target terminal, and the next rotation process is executed based on the updated first rotation direction.

[0063] The optical power collection data for each rotation is analyzed to find the position with the maximum optical power value. This position is the center of the light spot formed by the transmitted light beam in the current state, which usually means the point where the light beam energy is most concentrated and the optical communication link efficiency is the highest. Compare the determined light spot center with the geometric center of the receiving lens of the second communication terminal. If the two do not coincide, it means that the optical axis alignment state has not yet reached the optimal state and needs further adjustment. According to the relative position of the light spot center and the receiving lens center, update the first rotation direction of the carrier platform to perform the next rotation process. For example, if the light spot center is to the right of the receiving lens center, the carrier platform should be adjusted to the left for the next rotation, and vice versa. Such an update ensures that each rotation can be closer to the optimal alignment state of the optical communication link. Finally, based on the updated first rotation direction, control the carrier platform to perform the next rotation process. This continuous adjustment process continues until the light spot center coincides with the receiving lens center.

[0064] In this embodiment of the present invention, dynamic alignment of the optical subsystem's transmitting and receiving optical axes with each other is achieved by precisely analyzing optical power data to determine the center of the transmitted light beam's spot. Specifically, a closed-loop control strategy updates the platform's rotational direction in real time based on the relative position of the light beam's center and the center of the receiving lens, ensuring that each rotation step is directed toward improving the efficiency of the optical communication link. This dynamic alignment process significantly improves the accuracy and efficiency of optical axis alignment and reduces signal loss caused by the light beam's deviation from the center of the receiving lens.

[0065] Furthermore, after determining the spot center of the emitted light beam based on the optical power acquisition data, it also includes: taking the center of the receiving lens as a reference point, determining the periphery of the spot of the emitted light beam based on a preset optical power attenuation value; obtaining the size of the periphery of the spot to obtain the periphery size data of the spot; and verifying whether the center of the spot coincides with the center of the receiving lens based on the periphery size data of the spot.

[0066] It should be noted that the termination condition for the iterative rotation of the first communication terminal is that the center of the light spot is found at the second communication terminal and that the light spot center coincides with the lens center and is symmetrically distributed. Therefore, after determining the light spot center of the transmitted beam, it is necessary to verify whether the light spot center determined based on the optical power data is indeed the center of the transmitted beam. Using the geometric center of the receiving lens of the second communication terminal as a reference point, a preset threshold for optical power attenuation (for example, 10% of the peak optical power) is set. This threshold is used to define the outer boundary of the light spot, that is, the point where the beam energy begins to significantly decrease. Using a free-space optical power meter, starting from the center of the receiving lens and moving in different directions, positions on the outer boundary of the transmitted beam spot are found. These positions are the points where the optical power value first drops below the preset attenuation threshold, and together they form the outer contour of the light spot. The coordinates of all positions on the outer boundary of the light spot are recorded, and based on these coordinates, the outer dimensions of the light spot are calculated. Generally, the outer dimension data of the light spot reflects the energy distribution of the light beam at the receiving end, including maximum length, width, and shape characteristics. Based on the calculated spot perimeter data, the distribution of the spot along the lens center is analyzed to determine whether the spot perimeter is symmetrically distributed along the lens center. This determines whether the spot center is located at the center of the receiving lens. If the spot center coincides with the lens center, it indicates that the spot center of the transmitted beam has accurately fallen at the center of the receiving lens, satisfying the condition that the optical subsystem's transmitting optical axis is coaxial with the receiving optical axis at the opposite end.

[0067] Step S103 : Based on the second rotation step and the second rotation direction, the carrying platform is controlled to start rotating on the basis of the first coarse adjustment position.

[0068] In the above step S103, on the basis of the rough calibration of the first communication terminal, the alignment accuracy is further improved to achieve more stringent optical axis parallelism requirements. Based on the first coarse adjustment result, a smaller rotation step is set. The purpose of this setting is to explore a more precise coaxial relationship between the transmitting lens and the receiving lens of the optical subsystem through finer-grained adjustments on the basis of the first coarse adjustment position. The second rotation step should be smaller than the first rotation step to achieve a more delicate optical axis alignment process. While setting the second rotation step, it is also necessary to determine an optimization direction, that is, the second rotation direction, which can be a direction on the horizontal plane or a direction on the vertical plane. Based on the set second rotation step and the second rotation direction, the carrier platform (such as a drone gimbal or a ground turntable) is controlled to perform more precise rotation adjustments to ensure that the camera subsystem and the optical subsystem are accurately calibrated within the maximum allowable bit error rate deviation.

[0069] Step S104: In the process of controlling the support platform to rotate based on the second rotation step and the second rotation direction, a boundary offset value that generates a preset bit error rate is determined, a first fine-tuning position of the support platform is determined based on the boundary offset value, and the camera subsystem is precisely calibrated based on the first fine-tuning position so that the camera optical axis of the camera subsystem is parallel to the optical axes of the receiving lens and the transmitting lens of the optical subsystem.

[0070] It should be noted that in wireless optical communications, optical signals are transmitted through the air. The receiving end needs to use an optical system to focus the received optical signals and couple them to a photodetector. The efficiency and quality of this process are directly affected by the accuracy of the optical axis alignment. When the optical axis is accurately aligned, the optical signal can enter the photodetector directly along the optical axis of the receiving lens, with uniform energy distribution and a low bit error rate (BER) in the communication link. However, when the optical axis is not accurately aligned, the optical signal may enter the receiving lens at an oblique angle, resulting in uneven energy distribution on the photodetector. Some optical signals may not be captured by the detector, causing the BER to increase.

[0071] In step S104, the bit error rate (BER) is a sensitive indicator for measuring the quality and alignment accuracy of the optical communication link. The BER can be accurately read. When the transmitted light beam is not precisely aligned with the optical system of the receiving terminal, the optical signal will suffer varying degrees of loss during transmission, resulting in a decrease in the signal quality detected by the receiving end, manifested as an increase in the BER. As optical axis alignment becomes increasingly precise, optical signal loss decreases, and the BER accordingly decreases. The BER also intuitively reflects the operating status of the communication link and is not directly affected by external environmental factors (such as temperature and humidity). It primarily depends on the alignment accuracy between the light beam and the receiving end, as well as the performance of the optical communication system itself. Therefore, using the BER as an adjustment metric allows for precise calibration of communication terminals. The boundary of the BER actually refers to a small range within the optical axis alignment state. Beyond this range, the optical signal reception efficiency significantly decreases, causing the BER to begin to significantly increase. This boundary can be considered the tolerance limit of the optical communication system for optical axis alignment. By finding this boundary, the maximum allowable deviation of the optical axis alignment can be determined, and the optical axis alignment can then be adjusted to ensure that the optical signal remains within this maximum allowable deviation range.

[0072] By rotating the carrying platform, the deviation between the optical subsystem and the camera subsystem when a preset bit error rate is generated is determined, and then the camera subsystem is fine-tuned to ensure that the camera optical axis of the camera subsystem is parallel to the optical axes of the receiving lens and the transmitting lens of the optical subsystem, thereby completing the precise calibration of the optical subsystem and the camera subsystem.

[0073] Furthermore, the second rotation direction at least includes: a first direction on the horizontal plane, a second direction on the horizontal plane, the first direction is opposite to the second direction, and in the process of controlling the rotation of the carrying platform, the step of determining the boundary offset value for generating a preset bit error rate includes: step one, taking the first coarse adjustment position as the initial position, controlling the carrying platform to rotate in the first direction on the basis of the initial position until the light signal received in the receiving lens generates a preset bit error rate, and recording the first offset value of the carrying platform when the preset bit error rate is generated, wherein the first direction is a direction that causes the imaging position of the target image of the target recognition in the camera subsystem to shift in the opposite direction of the first direction, and the first offset value includes at least one of the following: a first offset step of the carrying platform deviating from the initial position on the horizontal plane, a first pixel center offset value of the target image of the target recognition deviating from the pixel center; step two, Control the supporting platform to rotate in a second direction based on the initial position until the light signal received by the receiving lens generates a preset bit error rate, and record the second offset value when the preset bit error rate is generated, wherein the second direction is a direction that causes the imaging position of the target recognition target image in the camera subsystem to translate in the opposite direction of the second direction, and the second offset value includes at least one of the following: a second offset step of the supporting platform deviating from the initial position on the horizontal plane, and a second pixel center offset value of the target recognition target image deviating from the pixel center; step three, calculate the average value of the first offset value and the second offset value to obtain the average level offset value; step four, repeat the above steps one to three, perform iterative calculation until the number of iterations reaches a preset number threshold, and average the average level offset values obtained by each iterative calculation to obtain the boundary offset value generated by the preset bit error rate.

[0074] Specifically, the carrying platform is controlled to rotate clockwise or counterclockwise on the horizontal plane to find the boundary offset value when the optical subsystem generates a preset bit error rate on the horizontal plane. The boundary offset value can be defined by two ways: the carrying platform deviates from the initial position or the imaging position of the target recognition target in the camera deviates from the pixel center. In the first step, the first coarse adjustment position of the carrying platform is used as the initial position for fine adjustment during rough calibration. The carrying platform is controlled to rotate along the first direction on the horizontal plane based on the initial position. The first direction can be clockwise or counterclockwise. During the rotation of the carrying platform, the optical signal emitted by the opposite end will deviate from the receiving end. The incident light is incident from the center of the lens, and the position of the target recognition target is parallel to the position of the optical subsystem. At this time, the imaging position of the target recognition target in the camera will also deviate from the pixel center. For example, if the carrier platform is rotated counterclockwise on the horizontal plane, the incident light beam from the opposite end is incident obliquely to the left, and the imaging position of the target recognition target in the camera will shift to the right. During the rotation process, the bit error rate change at the receiving end of the optical subsystem is continuously monitored until the bit error rate reaches the preset value for the first time. The first offset step of the carrier platform from the initial position or the first pixel center offset value of the target recognition target image from the pixel center when the preset bit error rate is generated is determined to obtain the first offset value. In the second step, after completing the first step, the carrier platform returns to the initial position, and then the same operation is performed along the second direction on the horizontal plane, that is, the carrier platform is controlled to rotate in the direction opposite to the first direction. Similarly, the bit error rate change is monitored until it reaches the preset value, and the second offset step of the carrier platform or the second pixel center offset value of the target recognition target image from the pixel center is recorded to obtain the second offset value. Based on the first and second offset values obtained in steps 1 and 2, the average of these values is calculated to obtain a horizontal horizontal offset value. The above steps are repeated to calculate the average value, resulting in a boundary offset value that produces a predetermined bit error rate. This value reflects the optical axis alignment deviation between the transmitting and receiving lenses of the optical subsystem in the horizontal plane, indicating the edge point where the beam coupling efficiency decreases.

[0075] Furthermore, the second rotation direction also includes: a third direction on the vertical plane, a fourth direction on the vertical plane, the third direction and the fourth direction are opposite, and in the process of controlling the rotation of the carrying platform, the step of determining the boundary offset value for generating a preset bit error rate also includes: step one, taking the first coarse adjustment position as the initial position, controlling the carrying platform to rotate in the third direction on the basis of the initial position, until the light signal received by the receiving lens generates a preset bit error rate, and recording the third offset value when the preset bit error rate is generated, wherein the third direction is a direction that causes the imaging position of the target recognition target image in the camera subsystem to shift in the opposite direction of the three directions, and the third offset value includes at least one of the following: a third offset step of the carrying platform from the initial position on the vertical plane, a third pixel center offset value of the target recognition target image from the pixel center; step two, controlling the carrying platform The carrier platform rotates in a fourth direction based on the initial position until the light signal received by the receiving lens generates a preset bit error rate, and records a fourth offset value when the preset bit error rate is generated, wherein the fourth direction is a direction that causes the imaging position of the target recognition target image in the camera subsystem to shift in the opposite direction of the fourth direction, and the fourth offset value includes at least one of the following: a fourth offset step of the carrier platform deviating from the initial position in the vertical plane, and a fourth pixel center offset value of the target recognition target image deviating from the pixel center; in step three, calculating the average value of the third offset value and the fourth offset value to obtain an average vertical offset value; in step four, repeating steps one to three above, performing iterative calculations until the number of iterations reaches a preset number threshold, and averaging the average vertical offset values obtained from each iterative calculation to obtain a boundary offset value generated by the preset bit error rate.

[0076] Specifically, in addition to rotation on the horizontal plane, the supporting platform can also be controlled to perform pitch rotation along the vertical plane. With the first coarse adjustment position of the supporting platform as the initial position, the supporting platform is controlled to perform fine-tuning rotation in a third direction on the vertical plane. For example, the supporting platform is controlled to rotate in the upward direction on the vertical plane, so that the light beam emitted from the opposite end is incident obliquely downward, and the imaging position of the target recognition target in the camera moves upward. During the rotation process, the bit error rate change at the receiving end of the optical subsystem is continuously monitored until the bit error rate reaches a preset value. The third offset step of the supporting platform from the initial position or the third pixel center offset value of the target recognition target from the pixel center is recorded at this time to obtain a third offset value. Subsequently, the supporting platform returns to the initial position and then performs fine-tuning rotation in a second direction on the vertical plane. The second direction is the direction opposite to the first direction on the vertical plane. Similarly, the bit error rate change is observed during the rotation process. When the bit error rate reaches the preset value, the fourth offset step of the supporting platform from the initial position or the fourth pixel center offset value of the target recognition target from the pixel center is recorded. Based on the third offset value and the fourth offset value obtained during fine-tuning on the vertical plane, the average value of the two is calculated to obtain an average vertical offset value, and the above steps are repeated to perform iterative adjustment to determine the boundary offset value that produces a preset bit error rate on the vertical plane.

[0077] Furthermore, the first fine-tuning position of the carrier platform is determined based on the boundary offset value, and the step of accurately calibrating the camera subsystem based on the first fine-tuning position includes: controlling the carrier platform to rotate in the direction indicated by the boundary offset value to obtain the first fine-tuning position of the carrier platform; obtaining the imaging offset position of the target recognition target image in the camera subsystem at the first fine-tuning position of the carrier platform; adjusting the angle of the camera subsystem based on the imaging offset position, and monitoring the imaging position of the target recognition target image during the adjustment process until the imaging position of the target recognition target image coincides with the pixel center of the camera subsystem, thereby completing the accurate calibration of the camera subsystem.

[0078] Specifically, after determining the boundary offset value that triggers a preset bit error rate, the carrier platform is controlled to perform fine-tuning rotation in the direction indicated by the boundary offset value, or the carrier platform is controlled to move the image position of the image recognition target toward the position indicated by the boundary offset value. This action aims to adjust the positions of the optical subsystem and the camera subsystem to a position closer to the ideal optical axis alignment. After the carrier platform is fine-tuned, the imaging offset position of the target recognition target image in the camera subsystem is acquired. The imaging offset position refers to the relative positional difference between the image center of the target recognition target on the camera's CCD imaging plate and the center of the camera pixel. It is an important reference for measuring the alignment of the optical axes of the optical subsystem and the camera subsystem. The acquired imaging offset position is used to adjust the angle of the camera subsystem using a micro-angle adjustment mechanism. During this adjustment process, the imaging position of the target recognition target image is continuously monitored. The goal of the adjustment is to gradually bring the image center closer to, and ultimately coincide with, the camera pixel center. This step is critical to the entire precision calibration process. By fine-tuning the camera angle, errors along the optical axis can be effectively reduced, improving the coupling efficiency between the light beam and the receiving lens. When the image position of the target recognition target completely coincides with the pixel center of the camera subsystem, the optical axis alignment between the optical subsystem and the camera subsystem has reached a highly accurate calibration state. At this point, the light beam can be coupled into the receiving lens with minimal loss, significantly reducing the bit error rate and significantly improving the stability and performance of the optical communication link.

[0079] Furthermore, by calibrating the communication terminal so that the optical axis of the camera at this end is parallel to the optical axes of the receiving and transmitting ends, and coaxial with the optical axis of the camera at the other end, the system can monitor the alignment status of the optical axis in real time by observing and analyzing the camera image, and make necessary fine-tuning, thus realizing remote monitoring and automated calibration. This is particularly important for optical communication systems on mobile platforms such as drones. Even if the drone encounters wind interference, attitude changes, etc. during flight, it can adjust its attitude through real-time feedback from the camera image, maintain beam alignment, and ensure the continuous stability of the communication link.

[0080] Through the above steps, the rotation of the carrying platform is controlled based on the first rotation step and the first rotation direction, and in the process of controlling the carrying platform to rotate based on the first rotation step and the first rotation direction, the optical power acquisition data of the second target terminal is received, the first coarse adjustment position of the carrying platform is determined based on the optical power acquisition data, and the camera subsystem is roughly calibrated with the first coarse adjustment position as a reference position, so that the degree of optical axis deviation between the optical axis of the camera subsystem and the optical axis of the optical subsystem is reduced to a preset condition, wherein the second target terminal is a terminal that performs wireless optical communication with the first target terminal, and then the carrying platform is controlled to start rotating on the basis of the first coarse adjustment position based on the second rotation step and the second rotation direction, and finally, in the process of controlling the carrying platform to rotate based on the second rotation step and the second rotation direction, the boundary offset value that generates a preset bit error rate is determined, the first fine adjustment position of the carrying platform is determined based on the boundary offset value, and the camera subsystem is accurately calibrated on the basis of the first fine adjustment position, so that the camera optical axis of the camera subsystem is parallel to the optical axes of the receiving lens and the transmitting lens of the optical subsystem.

[0081] In this embodiment, a two-stage calibration process is used to first achieve preliminary alignment between the optical subsystem and the camera subsystem, ensuring that the optical signal can be transmitted to the signal receiving end. Then, a more refined calibration is performed by finding the boundary offset value that produces a preset bit error rate, further improving the alignment accuracy and reducing the bit error rate during communication. This achieves high-precision optical axis alignment between the drone and the ground wireless optical communication terminal, reducing optical loss and signal interference during transmission. Through the two stages of coarse adjustment and fine adjustment, the technical effect of improving the calibration accuracy of the communication terminal is achieved, thereby ensuring that the camera optical axis is parallel to the optical axes of the transmitting and receiving lenses of the optical subsystem, optimizing the coupling efficiency of the optical communication link, and improving the stability of the communication and the data transmission rate. This solves the technical problem in the related art of low calibration accuracy of the communication terminal, which leads to low stability of the communication link.

[0082] The following describes it in detail with reference to another embodiment.

[0083] Example 2

[0084] According to an embodiment of the present invention, an embodiment of a calibration method for a wireless optical communication terminal is also provided. The method is applied to a second target terminal. A carrying platform is deployed on the second target terminal, and an optical subsystem and a camera subsystem are installed on the carrying platform.

[0085] Figure 2 FIG. 1 is a flow chart of another optional calibration method for a wireless optical communication terminal according to an embodiment of the present invention. Figure 2 As shown, the calibration method of the wireless optical communication terminal includes:

[0086] Step S201: receiving a data collection request sent by a first target terminal, and based on the data collection request, collecting optical power data received by a second target terminal using a free space optical power meter to obtain optical power collection data of the second target terminal, wherein the first target terminal is a terminal performing wireless optical communication with the second target terminal;

[0087] Step S202: Returning the optical power collected data of the second target terminal to the first target terminal;

[0088] Step S203: upon receiving the rough calibration result of the first target terminal, controlling the rotation of the carrying platform based on the first rotation step and the first rotation direction; in the process of controlling the rotation of the carrying platform based on the first rotation step and the first rotation direction, receiving the optical power acquisition data of the first target terminal, determining the second coarse adjustment position of the carrying platform based on the optical power acquisition data of the first target terminal, and roughly calibrating the camera subsystem with the second coarse adjustment position as a reference position, so that the degree of optical axis deviation between the optical axis of the camera subsystem and the optical axis of the optical subsystem is reduced to a preset condition, wherein the second target terminal is a terminal that performs wireless optical communication with the first target terminal.

[0089] It should be noted that the optical power collection data of the first target terminal is collected when the carrying platform on the first target terminal is at the first coarse adjustment position.

[0090] In step S204, when the precise calibration is completed at the first target terminal, the carrier platform is controlled to rotate on the basis of the second coarse adjustment position based on the second rotation step and the second rotation direction. In the process of controlling the carrier platform to rotate based on the second rotation step and the second rotation direction, the boundary offset value that produces a preset bit error rate is determined, and the second fine adjustment position of the carrier platform is determined based on the boundary offset value. The camera subsystem is precisely calibrated on the basis of the second fine adjustment position so that the camera optical axis of the camera subsystem is parallel to the optical axes of the receiving lens and the transmitting lens of the optical subsystem.

[0091] It should be noted that the boundary offset value is determined based on the optical signal emitted when the carrying platform on the first target terminal is in the first fine adjustment position.

[0092] It should be noted that the specific implementation methods and beneficial effects of performing rough calibration and precise calibration on the second target terminal correspond to those in Example 1 and will not be described in detail here.

[0093] The following describes it in detail with reference to another embodiment.

[0094] Example 3

[0095] A target terminal provided in this embodiment is used to execute the various implementation steps of the calibration method for the wireless optical communication terminal in Example 1. Its specific implementation methods and beneficial effects correspond to those of the aforementioned method embodiment and are not repeated here.

[0096] Figure 3 is a schematic diagram of an optional target terminal according to an embodiment of the present invention, such as Figure 3 As shown, the target terminal is a part of the wireless optical communication terminal, which communicates with other terminals by transmitting and receiving optical signals. The target terminal can be the first target terminal or the second target terminal mentioned above. The target terminal includes: an optical subsystem, a camera subsystem, and a carrying platform, wherein:

[0097] An optical subsystem, comprising a receiving lens and a transmitting lens, for receiving and transmitting optical signals;

[0098] A camera subsystem, including a camera, wherein the camera subsystem is used for image recognition;

[0099] The carrying platform is used to fix the optical subsystem and camera subsystem.

[0100] The optical subsystem, camera subsystem, and target recognition target together constitute the optical communication system. The camera subsystem is primarily used to locate and identify targets, as well as monitor the alignment of the optical axis. By capturing images of the target recognition target, it can determine the relative position and angle between the communication terminal and other terminals. During the alignment and debugging process of optical communications, the camera subsystem can help the operator identify the target and perform preliminary alignment. During fine-tuning, by monitoring changes in the image of the target recognition target, feedback on the accuracy of the optical axis alignment can be provided until optimal beam coupling is achieved. The camera subsystem typically includes a high-resolution industrial camera and optical lenses, and sometimes also includes image processing software for analyzing and processing the image information of the target recognition target.

[0101] The optical subsystem is the core component of optical communications, responsible for transmitting, receiving, and processing optical signals. It includes a light source (transmitter), a light detector (receiver), and related signal processing circuitry. The light source converts electrical signals into optical signals, which are then focused into a beam through a transmitting lens and transmitted. The light detector converts the received optical signals back into electrical signals, completing data transmission across the communication link.

[0102] The target terminal also includes: a target recognition target, which includes three characteristic circles for target recognition and a central recognition circle for fine adjustment, and is used to assist in the calibration of the optical subsystem and the camera subsystem.

[0103] The target recognition target is a special marker used to assist in optical axis alignment. It is typically placed in a conspicuous location on the opposite communication terminal, fixed above the optical subsystem and perpendicular to it. Its design and pattern (such as the black circle on the periphery and the through-hole in the center) enable the camera subsystem to easily identify the target. By analyzing the image of the target recognition target, the operator or automatic control system can determine whether the optical axis alignment is accurate, as well as the direction and magnitude of any necessary adjustments. The image processing results of the target recognition target serve as the basis for fine-tuning the camera and optical subsystems, ensuring that the light beams are properly coupled at the receiving end, reducing bit error rates and improving communication quality.

[0104] The camera subsystem provides visual feedback for alignment and commissioning, the optics subsystem transmits and receives optical communication signals, and the target recognition target serves as a positioning reference during the alignment process. These three subsystems complement each other, ensuring precise alignment and stable data transmission between optical communication terminals, and are key components for achieving efficient free-space optical communication.

[0105] In medium- and long-distance drone communication scenarios, calibrating the communication terminals is the basis for establishing a stable communication link. The calibration result ensures that the optical axes of the receiving lens and the transmitting lens in the optical subsystem are parallel to the optical axis of the camera in the camera subsystem. This enables the optical communication system to monitor the alignment status of the two terminals through real-time observation and analysis of camera images by the camera subsystem, and to make necessary fine-tuning to ensure that the optical signal can always be accurately transmitted to the other end, thus establishing a stable communication link.

[0106] Figure 4 is a schematic diagram of an optional optical communication system according to an embodiment of the present invention Figure 1 , Figure 5 is a schematic diagram of an optional optical communication system according to an embodiment of the present invention Figure 2 ,like Figure 4 and Figure 5As shown, the optical communication system includes a target recognition target 1, a camera subsystem 2, and an optical subsystem 4, and the target recognition target 1 is connected and fixed to the camera subsystem 2 and the optical subsystem 4 via a switching splint 3. The optical communication system is installed on a carrier platform to form a communication terminal. The carrier platform can be a UAV gimbal or a ground terminal turntable, which can be rotated to any angle in free space to control the pointing angle of the optical subsystem and the camera subsystem. In addition to providing a stable bracket, the switching splint 3 can also be replaced at will according to the different requirements of the ground turntable or the UAV gimbal. At the same time, the splint reasonably distributes the center of mass of the camera and the optical subsystem, which facilitates the balance adjustment of the UAV gimbal (if the mass difference between the camera and the optical subsystem is too large or the distribution is uneven, making it difficult to adjust the balance of the gimbal, the splint structure can be changed or a counterweight can be added to the splint to change the structural center of gravity of the terminal as a whole, which makes the gimbal in a balanced state).

[0107] Figure 6 is a schematic diagram of an optional camera subsystem according to an embodiment of the present invention Figure 1 , Figure 7 is a schematic diagram of an optional camera subsystem according to an embodiment of the present invention Figure 2 ,like Figure 6 and Figure 7 As shown, the camera subsystem includes: camera lens 2-1, telephoto lens 2-2, camera mounting frame 2-3, camera frame 2-4, and long-tongue L-shaped camera bracket 2-5. Camera lens 1 is a telephoto industrial camera using a 12-120mm low-distortion, high-definition industrial lens. To achieve a longer focal length and clearer object recognition, a 4x telephoto lens 2-2 is used. By converting the main lens into a telephoto lens, the telephoto lens increases the optical focal length. The telephoto lens is multiplied by the telephoto lens's magnification and the optical focal length. Adding a telephoto lens can increase the focal length without significantly increasing the space required. Camera lens 2-1 and telephoto lens 2-2 are secured to camera mounting frame 2-3 and protected by camera frame 2-4. The long-tongue L-shaped camera brackets 2-5 are fixed to each other using screws and are fixed under the camera's CCD imaging board. The vertical portion of the rear end of the L-board is not connected to the camera, but leaves space for adjustment of the precision screw sleeve. Since the camera lens is heavy, this connection is prone to being top-heavy. Therefore, the gap between the long-tongue L-shaped camera bracket 2-5 and the camera can be filled with a flexible medium to resist position shifting caused by the heavy lens.

[0108] Furthermore, the camera subsystem also includes: a micro-angle adjustment module, including multiple precision thread pairs and a top ball, which is used to adjust the angle of the camera subsystem so that the optical axis of the receiving lens and the optical axis of the transmitting lens of the optical subsystem are parallel to the camera optical axis of the camera subsystem.

[0109] Figure 8is a schematic diagram of an optional camera subsystem according to an embodiment of the present invention Figure 3 ,like Figure 8 As shown, the vertical part of the long-tongue L-shaped camera bracket 2-5 is fixed to the camera frame 2-4 by means of four precision thread pairs 2-6 and a 6mm precision top bead 2-8. Due to the existence of the precision top bead, there is a gap of 1-2mm between the vertical part and the frame. The precision thread pairs 2-6 and the precision threaded copper sleeve 2-7 form tension by means of threads, which tightly fixes the long-tongue L-shaped camera bracket 2-5 to the camera frame 2-4. When the tension of a certain precision thread pair is greater, the camera axis deflects to that position, thereby forming a micro-angle adjustment module.

[0110] The optical communication system has three axes: the optical axis of the transmitting lens, the optical axis of the receiving lens, and the optical axis of the camera.

[0111] After the communication terminal is set up, the optical axes of the optical subsystem, namely the optical axis of the transmitting lens (transmitting axis) and the optical axis of the receiving lens (receiving axis), are parallel. A camera at one end captures the target identification target at the other end. When the complete target identification target image appears in the image, that is, the three characteristic circles and the central identification circle appear in the image captured by the camera, it indicates that the two communication terminals are initially aligned.

[0112] Figure 9 is an imaging schematic diagram of an optional target recognition target according to an embodiment of the present invention, such as Figure 9 As shown, when three target feature recognition circles 7 and a center recognition circle 8 appear on the display screen 5 of the camera subsystem, it indicates that the two communication terminals are preliminarily aligned.

[0113] Depend on Figure 9 It can be seen that at this time, the center identification circle 8 and the center cross 6 of the camera do not coincide with each other. At this time, the camera optical axis is not coaxial with the receiving axis and the transmitting axis. The light cannot be coupled to the multi-mode light, that is, the optical communication system cannot work, so three-axis adjustment is required.

[0114] Taking end A (corresponding to the first target terminal mentioned above) and end B (corresponding to the second target terminal mentioned above) as an example, assuming that communication terminals are deployed at ends A and B respectively, end A is adjusted first, and end B is fixed. Because the transmitting axis is parallel to the receiving axis, the transmitting axis can be used to determine the correct direction of end A. Because the three axes are coaxial, the direction of end A is guided by the optical axis of the camera, and the emitted laser is invisible (even if visible light is used to transmit through the transmitting antenna, because the mode field diameter of visible light does not match that of the optical fiber and the wavelength difference between visible light and near-infrared light also makes the focal lengths of the two different, the visible light emitted by the transmitting antenna is very divergent. The light spot of long-distance transmission is very large, and the visible light cannot be observed at long distances). Therefore, a free-space optical power meter is used to find the center of the light spot of the transmitted beam in front of the receiving lens of end B.

[0115] Specifically, control the stepper motor of the carrying platform (turntable or pan / tilt) at end A to change the direction of the optical subsystem and camera subsystem, point the laser of the transmitting axis to the receiving system at end B, and find the center of the light spot by moving the optical power meter in front of the receiving lens at end B. Because the aperture of the optical power meter is small and may be smaller than the spot size, the measured center of the light spot is inaccurate and belongs to rough calibration. When looking for the center of the light spot, take the center of the receiving lens at end B as the starting point, and find the periphery of the light spot according to the fixed attenuation value. According to the distribution of the periphery of the light spot, reversely infer whether the center of the light spot is correct. When the center of the beam emitted from end A is at the center of the receiving lens at end B, the optical subsystems of ends A and B are coaxial. If the target image captured by the camera at end A deviates from the camera's pixel center, that is, the center identification circle 8 and the camera's center cross 6 do not coincide with each other, tighten the stepper motor at end A and adjust the micro-angle adjustment module at the rear of the camera subsystem to move the imaging position of the target identification target to the pixel center of end A, so that the center of center identification circle 8 coincides with the center cross 6 corresponding to the camera's pixel center. At this point, the optical axis of the camera at end A and the optical axis of the optical subsystem at end A are roughly aligned, completing the rough calibration.

[0116] Follow the same steps to adjust the camera axis at end B to eliminate the impact of the target's tilt distortion on the camera's image processing. Through multiple iterations, the coaxial errors of the three axes at ends A and B are gradually reduced. When the three axes at ends A and B are essentially parallel, the light incident angle requirements of the optical subsystem's receiving antenna are met. The laser emitted from one end can be received at the other optical terminal, and the optical subsystem can function normally. At this point, the optical subsystem can adjust the laser light entering the subsystem so that the incident laser light can be coupled into the optical fiber. At this point, the FPGA can measure the energy value of the laser light after photoelectric conversion.

[0117] When the other end has also completed the coarse adjustment steps described above, the signal light is modulated, decoded, and received at the receiving end, with the FPGA used for bit error rate analysis. When the incident light beam is incident at an angle, resulting in uneven energy at the receiving end of the fiber and a deviation from the Gaussian spot shape, bit errors can occur, leading to higher bit error rates.

[0118] On the basis of rough calibration, control the rotation of the stepper motor or pan-tilt head to find the boundary of the preset bit error rate. For example, rotate the turntable so that the image of the target recognition target in the camera subsystem at one end is translated to the left by a certain distance. The light beam is incident at an angle to the right, and a preset bit error rate is generated, such as 10^-5. Record the offset step or pixel deviation value of the carrier platform at this time, then rotate the turntable and translate it to the right to find the point where the bit error rate is generated due to the left oblique incidence. Record the offset step or pixel deviation value of the carrier platform that is translated to the right at this time, take the average of the two offset steps, or subtract the center pixel from the average pixel deviation to obtain the value of the camera axis deviation from the center axis. Repeat multiple times, record the average value, and obtain the boundary offset value that produces the preset bit error rate. Move the carrier platform to the position indicated by the boundary offset value, and adjust the camera optical axis by adjusting the micro-angle adjustment module at the tail of the camera so that the imaging position of the target recognition target in the camera subsystem is located at the center of the pixel. Repeat this process multiple times to make the camera optical axis parallel to the receiving axis and the transmitting axis, completing the calibration of the communication terminal. This allows the optical signals at both ends to be accurately transmitted to the receiving end at the other end and coupled to the coupling optical fiber of the optical subsystem. At the same time, the alignment of the optical communication system at the other end can be observed in real time through the camera.

[0119] In this embodiment, a two-stage calibration process is used to first achieve preliminary alignment between the optical subsystem and the camera subsystem, ensuring that the optical signal can be transmitted to the signal receiving end. Then, a more refined calibration is performed by finding the boundary offset value that produces a preset bit error rate, further improving the alignment accuracy and reducing the bit error rate during communication. This achieves high-precision optical axis alignment between the drone and the ground wireless optical communication terminal, reducing optical loss and signal interference during transmission. Through the two stages of coarse adjustment and fine adjustment, the technical effect of improving the calibration accuracy of the communication terminal is achieved, thereby ensuring that the camera optical axis is parallel to the optical axes of the transmitting and receiving lenses of the optical subsystem, optimizing the coupling efficiency of the optical communication link, and improving the stability of the communication and the data transmission rate. This solves the technical problem in the related art of low calibration accuracy of the communication terminal, which leads to low stability of the communication link.

[0120] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0121] In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0122] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only exemplary. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0123] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0124] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0125] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, etc. Various media that can store program codes.

[0126] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A calibration method for a wireless optical communication terminal, characterized in that: Applied to a first target terminal, wherein a carrying platform is deployed on the first target terminal, and an optical subsystem and a camera subsystem are installed on the carrying platform. The calibration method of the wireless optical communication terminal includes: controlling the rotation of the carrying platform based on a first rotation step and a first rotation direction; In a process of controlling the bearing platform to rotate based on a first rotation step and a first rotation direction, optical power acquisition data of a second target terminal is received, a first coarse adjustment position of the bearing platform is determined based on the optical power acquisition data, and the camera subsystem is roughly calibrated with the first coarse adjustment position as a reference position so that the degree of optical axis deviation between the optical axis of the camera subsystem and the optical axis of the optical subsystem is reduced to a preset condition, wherein the second target terminal is a terminal that performs wireless optical communication with the first target terminal; Controlling the carrying platform to start rotating based on the first coarse adjustment position based on the second rotation step and the second rotation direction; In the process of controlling the support platform to rotate based on the second rotation step and the second rotation direction, a boundary offset value that produces a preset bit error rate is determined, and a first fine-tuning position of the support platform is determined based on the boundary offset value. Based on the first fine-tuning position, the camera subsystem is precisely calibrated so that the camera optical axis of the camera subsystem is parallel to the optical axes of the receiving lens and the transmitting lens of the optical subsystem.

2. The method according to claim 1, characterized in that The steps of determining a first coarse adjustment position of the carrying platform based on the optical power acquisition data, and roughly calibrating the camera subsystem with the first coarse adjustment position as a reference position include: Determining the spot center of the emitted light beam according to the optical power acquisition data, wherein the optical power acquisition data is acquired by a free space optical power meter; When the center of the light spot coincides with the center of the receiving lens on the second target terminal, determining that the transmitting lens of the first target terminal and the receiving lens of the second target terminal are coaxial, and obtaining a first coarse adjustment position of the carrying platform; Taking the first coarse adjustment position as a reference position, obtaining an imaging position of a target recognition image in the camera subsystem; The imaging position of the target recognition target image is adjusted to the pixel center of the camera subsystem to complete the rough calibration of the camera subsystem.

3. The method according to claim 2, characterized in that The step of determining the spot center of the emission light beam according to the optical power acquisition data comprises: The position where the optical power value of the emitted light beam is the largest is determined by the optical power acquisition data, and the position where the optical power value is the largest is used as the center of the light spot of the emitted light beam. After determining the center of the light spot, the first rotation direction of the carrier platform for the next rotation process is updated according to the relative position of the center of the light spot and the center of the receiving lens on the second target terminal, and the next rotation process is performed based on the updated first rotation direction.

4. The method according to claim 2, characterized in that After determining the spot center of the emission light beam according to the optical power acquisition data, the method further includes: Taking the center of the receiving lens as a reference point, determining the periphery of the light spot of the emission light beam based on a preset optical power attenuation value; Obtaining the size of the periphery of the light spot to obtain light spot periphery size data; Verify whether the center of the light spot coincides with the center of the receiving lens based on the light spot peripheral size data.

5. The method according to claim 1, wherein The second rotation direction includes at least: a first direction on a horizontal plane and a second direction on the horizontal plane, the first direction being opposite to the second direction. In the process of controlling the rotation of the carrying platform, the step of determining a boundary offset value for generating a preset bit error rate includes: Step 1: With the first coarse adjustment position as the initial position, control the carrying platform to rotate in a first direction based on the initial position until the light signal received by the receiving lens generates the preset bit error rate, and record the first offset value of the carrying platform when the preset bit error rate is generated, wherein the first direction is a direction that causes the imaging position of the target image of the target recognition in the camera subsystem to shift in the opposite direction of the first direction, and the first offset value includes at least one of the following: a first offset step of the carrying platform deviating from the initial position on the horizontal plane, and a first pixel center offset value of the target image of the target recognition from the pixel center; Step 2: Controlling the carrying platform to rotate in a second direction based on the initial position until the optical signal received by the receiving lens generates the preset bit error rate, and recording a second offset value when the preset bit error rate is generated, wherein the second direction is a direction that causes the imaging position of the target image of the target recognition in the camera subsystem to shift in the opposite direction of the second direction, and the second offset value includes at least one of the following: a second offset step of the carrying platform from the initial position on the horizontal plane, and a second pixel center offset value of the target image from the pixel center. Step 3: Calculate the average of the first offset value and the second offset value to obtain a horizontal horizontal offset value; Step 4: Repeat steps 1 to 3 above and perform iterative calculations until the number of iterations reaches a preset threshold, and average the average horizontal offset values obtained from each iterative calculation to obtain the boundary offset value generated by the preset bit error rate.

6. The method according to claim 5, characterized in that The second rotation direction further includes: a third direction on the vertical plane and a fourth direction on the vertical plane, wherein the third direction is opposite to the fourth direction. In the process of controlling the rotation of the carrying platform, the step of determining the boundary offset value for generating a preset bit error rate further includes: Step 1: With the first coarse adjustment position as the initial position, control the carrying platform to rotate in a third direction based on the initial position until the optical signal received by the receiving lens generates the preset bit error rate, and record a third offset value when the preset bit error rate is generated, wherein the third direction is a direction that causes the imaging position of the target image of the target recognition in the camera subsystem to shift in the opposite direction of the three directions, and the third offset value includes at least one of the following: a third offset step of the carrying platform from the initial position on the vertical plane, and a third pixel center offset value of the target image from the pixel center. Step 2: Controlling the carrying platform to rotate in a fourth direction based on the initial position until the optical signal received by the receiving lens generates the preset bit error rate, and recording a fourth offset value when the preset bit error rate is generated, wherein the fourth direction is a direction that causes the imaging position of the target image of the target recognition target in the camera subsystem to shift in the opposite direction of the fourth direction, and the fourth offset value includes at least one of the following: a fourth offset step of the carrying platform from the initial position in the vertical plane, and a fourth pixel center offset value of the target image from the pixel center; Step 3: Calculate the average of the third offset value and the fourth offset value to obtain an average vertical offset value; Step 4: Repeat steps 1 to 3 above and perform iterative calculations until the number of iterations reaches a preset threshold, and average the average vertical offset values obtained from each iterative calculation to obtain the boundary offset value generated by the preset bit error rate.

7. The method according to claim 1, characterized in that The steps of determining a first fine-tuning position of the carrying platform based on the boundary offset value, and accurately calibrating the camera subsystem based on the first fine-tuning position include: Controlling the carrying platform to rotate in the direction indicated by the boundary offset value to obtain a first fine-tuning position of the carrying platform; Acquiring an imaging offset position of a target recognition target image in the camera subsystem at the first fine-tuning position of the carrying platform; The angle of the camera subsystem is adjusted based on the imaging offset position, and the imaging position of the target recognition target image is monitored during the adjustment process until the imaging position of the target recognition target image coincides with the pixel center of the camera subsystem, thereby completing the precise calibration of the camera subsystem.

8. A calibration method for a wireless optical communication terminal, characterized in that: Applied to a second target terminal, wherein a carrying platform is deployed on the second target terminal, and an optical subsystem and a camera subsystem are installed on the carrying platform. The calibration method of the wireless optical communication terminal includes: receiving a data collection request sent by a first target terminal, and collecting optical power data received by the second target terminal using a free space optical power meter based on the data collection request to obtain optical power collection data of the second target terminal, wherein the first target terminal is a terminal performing wireless optical communication with the second target terminal; Returning the optical power collection data of the second target terminal to the first target terminal; Upon receiving a rough calibration result of the first target terminal, controlling the rotation of the carrying platform based on a first rotation step and a first rotation direction; in the process of controlling the rotation of the carrying platform based on the first rotation step and the first rotation direction, receiving optical power acquisition data of the first target terminal, determining a second coarse adjustment position of the carrying platform based on the optical power acquisition data of the first target terminal, and roughly calibrating the camera subsystem with the second coarse adjustment position as a reference position, so that the degree of optical axis deviation between the optical axis of the camera subsystem and the optical axis of the optical subsystem is reduced to a preset condition, wherein the second target terminal is a terminal performing wireless optical communication with the first target terminal, and wherein the optical power acquisition data of the first target terminal is acquired when the carrying platform on the first target terminal is in the first coarse adjustment position; When the first target terminal completes precise calibration, the carrying platform is controlled to rotate on the basis of the second coarse adjustment position based on the second rotation step and the second rotation direction. In the process of controlling the carrying platform to rotate based on the second rotation step and the second rotation direction, the boundary offset value that generates a preset bit error rate is determined, and the second fine adjustment position of the carrying platform is determined based on the boundary offset value. Based on the second fine adjustment position, the camera subsystem is precisely calibrated so that the camera optical axis of the camera subsystem is parallel to the optical axis of the receiving lens and the optical axis of the transmitting lens of the optical subsystem, wherein the boundary offset value is determined based on the light signal emitted when the carrying platform on the first target terminal is in the first fine adjustment position.

9. A target terminal, characterized in that: include: An optical subsystem, comprising a receiving lens and a transmitting lens, for receiving and transmitting optical signals; A camera subsystem, comprising a camera, wherein the camera subsystem is used for image recognition; A carrying platform, used for fixing the optical subsystem and the camera subsystem; The target terminal includes a first target terminal or a second target terminal, the first target terminal executes the calibration method of the wireless optical communication terminal according to any one of claims 1 to 7, and the second target terminal executes the calibration method of the wireless optical communication terminal according to claim 8.

10. The target terminal according to claim 9, characterized in that: The camera subsystem further includes: The micro-angle adjustment module includes multiple precision thread pairs and a top ball, which is used to adjust the angle of the camera subsystem so that the optical axis of the receiving lens and the optical axis of the transmitting lens of the optical subsystem are parallel to the camera optical axis of the camera subsystem.

Images