Underwater wireless optical communication and azimuth measurement integrated system and method

Abstract

The invention provides an underwater wireless optical communication and azimuth measurement integrated system and method, and the system comprises a first communication device and a second communication device, the working wavelength of the communication devices is located in a visible light wave band, and bidirectional information transmission is carried out in a half-duplex communication mode; the first communication equipment comprises a first transmitting unit, a first receiving unit, a first processing unit, a first communication data interface and a first azimuth data interface; the second communication equipment comprises a second transmitting unit, a second receiving unit, a second processing unit, a second communication data interface and a second azimuth data interface; the system adopts a half-duplex communication mode to realize bidirectional data transmission, and all optical signals in two communication transmission directions can adopt the same wavelength or different wavelengths, so that the design flexibility is greatly improved; compared with a traditional underwater wireless optical communication system, only the light source layout and the photoelectric detector type are changed on the hardware level, so that the portability is high, and popularization and application are facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater communication, and in particular to an underwater wireless optical communication and azimuth measurement integrated system and method. Background Art

[0002] Underwater wireless optical communication technology generally uses visible light as an information carrier and transmits information through the propagation of light waves in water. This technology has the outstanding advantage of high transmission rate and has attracted widespread attention in the field of marine engineering in recent years. However, in practical applications, since optical signals propagate in a straight line in water, the transmission link of optical signals is very directional; and affected by the attenuation of water bodies, optical signals can only cover a limited area in water. This requires that the communication system must first enter each other's optical coverage area and establish a two-way transmission link in engineering applications. In the existing engineering implementation process, at least one terminal in the underwater wireless optical communication system is generally mounted on a mobile robot such as an autonomous underwater vehicle (AUV) or an unmanned remotely operated vehicle (ROV). In this application scenario, the underwater mobile robot first swims to the vicinity of the underwater cooperative target where data transmission is required, and then establishes a two-way optical communication transmission link between each other and completes the two-way data transmission. This requires the underwater mobile robot to be able to autonomously measure the relative orientation of the underwater cooperative target and adjust its own posture accordingly.

[0003] In the existing method, when the underwater mobile robot and the underwater cooperative target are far apart, the guidance method adopted is acoustic detection and positioning; when the distance is close, the optical vision method is adopted to accurately measure the position of the underwater cooperative target. In this optical vision measurement method, an underwater camera is generally installed on the mobile robot, and an additional light array with a certain spatial distribution is installed on the underwater cooperative target. The shape of the light pattern is captured by the camera, and the relative position of the underwater robot and the underwater cooperative target is measured according to the shape of the light pattern. In this process, in order to distinguish the light spots formed in the camera by the light signal for guidance and the light signal for communication, the existing related technology uses a colorimetric method or a geometric position method to identify the two light spots, thereby eliminating the interference of the communication light (see the patent "A method for measuring the position of an underwater wireless optical communication cooperative target", patent application number 202310905660.3, and the patent "A method, system and storage medium for underwater non-contact optical communication", patent application number 202410930272.5). This optical vision-based measurement device is independent of the wireless optical communication system, which greatly increases the system complexity in the communication process. In addition, the amount of image data that needs to be processed based on the optical vision azimuth measurement method is relatively large, which will increase the computational complexity of the azimuth measurement. In the related art, another method is that the communication receiving unit converges the arriving communication light signal to the photosensitive surface of the four-quadrant photodetector, and while realizing the communication data transmission, the direction of the cooperative target is measured according to the position information of the light spot on the detector surface (see patent: "Deep-sea blue-green laser communication receiving method and device based on four-quadrant detector", patent application number: 202310943781.7). However, this method is generally only suitable for underwater laser communications with small angles of emission, and can only measure the direction information of the communication cooperation target, and cannot obtain distance information. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides an integrated system and method for underwater wireless optical communication and azimuth measurement, which specifically includes:

[0005] In a first aspect, the present invention provides an underwater wireless optical communication and azimuth measurement integrated system, comprising:

[0006] A first communication device and a second communication device, wherein the working wavelengths of the first communication device and the second communication device are in the visible light band, and a half-duplex communication mode is adopted for bidirectional information transmission, a first communication data interface and a first azimuth data interface are provided on the first communication device, and a second communication data interface and a second azimuth data interface are provided on the second communication device;

[0007] The first communication device includes a first transmitting unit, a first receiving unit, and a first processing unit; the first transmitting unit includes four first light sources, each of which is distributed on the same plane and the center position of the light source forms a convex polygon structure;

[0008] The second communication device includes a second transmitting unit, a second receiving unit, and a second processing unit; the second transmitting unit includes four second light sources, each of which is distributed on the same plane and the center position of the light source forms a convex polygon structure;

[0009] The first receiving unit includes a first converging lens, a first four-quadrant photodetector, and four identical first transimpedance amplifiers, wherein the optical axis of the first converging lens is perpendicular to the photosensitive surface of the first four-quadrant photodetector and passes through the center of the photosensitive surface of the first four-quadrant photodetector;

[0010] The second receiving unit includes a second converging lens, a second four-quadrant photodetector, and four identical second transimpedance amplifiers, wherein the optical axis of the second converging lens is perpendicular to the photosensitive surface of the second four-quadrant photodetector and passes through the center of the photosensitive surface of the second four-quadrant photodetector;

[0011] The first processing unit is used to cache the data information from the first communication data interface to obtain first cached data; divide the first cached data into multiple data segments of preset lengths according to a preset time sequence to obtain multiple first data segments; based on the half-duplex communication mode, according to the acquisition order of each first data segment, control one or more first light sources to emit optical signals to transmit each first data segment in the form of an optical signal from underwater to a second receiving unit on a second communication device, so that the second communication device determines the orientation information of the first communication device according to the received optical signal;

[0012] The second processing unit is used to cache the data information from the second communication data interface to obtain second cached data, and divide the second cached data into multiple data segments of preset lengths according to a preset time sequence to obtain multiple second data segments; based on the half-duplex communication mode, according to the acquisition order of each second data segment, control one or more second light sources to emit optical signals to transmit each second data segment in the form of an optical signal from underwater to the first receiving unit on the first communication device, so that the first communication device determines the orientation information of the second communication device according to the received optical signal.

[0013] In a second aspect, the present invention further provides an underwater wireless optical communication and azimuth measurement integrated method, which is applied to any underwater wireless optical communication and azimuth measurement integrated system provided in the first aspect, and the method comprises:

[0014] S1, a first communication device and a second communication device establish a transmission link in a half-duplex communication mode based on preset communication parameters;

[0015] S2, the first processing unit caches the data information from the first communication data interface to obtain first cache data; the second processing unit caches the data information from the second communication data interface to obtain second cache data;

[0016] S3, the first processing unit divides the first cache data into a plurality of data segments of preset lengths according to a preset time sequence to obtain a plurality of first data segments; the second processing unit divides the second cache data into a plurality of data segments of preset lengths according to a preset time sequence to obtain a plurality of second data segments;

[0017] S4, based on the half-duplex communication mode, the first communication device controls one or more first light sources to emit light signals according to the acquisition order of each first data segment, so as to transmit each first data segment from underwater to the second communication device in the form of an optical signal, so that the second communication device determines the position information of the first communication device according to the received optical signal; the second communication device controls one or more second light sources to emit light signals based on the acquisition order of each second data segment, so as to transmit each second data segment from underwater to the first communication device in the form of an optical signal, so that the first communication device determines the position information of the second communication device according to the received optical signal.

[0018] Beneficial effects of the present invention:

[0019] 1. In the present invention, two communication devices of the underwater wireless optical communication system can measure each other's position information while realizing bidirectional data transmission, without the need for additional auxiliary equipment, thereby greatly reducing the complexity of the communication process.

[0020] 2. In the present invention, since a four-quadrant photodetector is used as the detector of the receiving unit, the directional information of the incident light can be measured; since an array light source with a certain arrangement in space is used as the transmitting unit, and these light sources can transmit light signals individually, when transmitting the navigation mark sequence, the light source in the communication transmitting unit can work in time-sharing mode, which helps to distinguish the output signals of different light sources after reaching the four-quadrant detector. In this way, the four-quadrant photodetector can obtain the directional information of different light sources in the array light source, and obtain the position information of the array light source based on these parameters. This method of obtaining azimuth information can be used in the case where the array light source is a small-angle laser, and can also be used in systems with wide-angle emitting light sources, and has wide practicality.

[0021] 3. The present invention adopts a half-duplex communication mode to realize bidirectional data transmission. The optical signals in the two transmission directions of the communication can use the same wavelength or different wavelengths, which greatly increases the flexibility of the design. Compared with the traditional underwater wireless optical communication system, the present invention only changes the light source layout and the type of photodetector at the hardware level, and has strong portability and is easy to promote and apply.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the architecture of an underwater wireless optical communication and azimuth measurement integrated system provided by the present invention;

[0024] Figure 2 A schematic diagram of a flow chart of an integrated method for underwater wireless optical communication and azimuth measurement provided by the present invention;

[0025] Figure 3 A schematic diagram of an experimental verification system for an underwater wireless optical communication and azimuth measurement integrated system provided by the present invention;

[0026] Figure 4 1 is a schematic diagram of a data transmission mode in a half-duplex communication cycle provided by the present invention;

[0027] Figure 5 A schematic diagram of a model for detecting the orientation of a light source array using a four-quadrant detector provided by the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0029] Figure 1 The schematic diagram of the architecture of an underwater wireless optical communication and azimuth measurement integrated system provided by the present invention is as follows: Figure 1 As shown, the system includes:

[0030] A first communication device and a second communication device, wherein the working wavelengths of the first communication device and the second communication device are in the visible light band, and a half-duplex communication mode is adopted for bidirectional information transmission, a first communication data interface and a first azimuth data interface are provided on the first communication device, and a second communication data interface and a second azimuth data interface are provided on the second communication device;

[0031] The first communication device includes a first transmitting unit, a first receiving unit, and a first processing unit; the first transmitting unit includes four first light sources, each of which is distributed on the same plane and the center position of the light source forms a convex polygon structure;

[0032] The second communication device includes a second transmitting unit, a second receiving unit, and a second processing unit; the second transmitting unit includes four second light sources, each of which is distributed on the same plane and the center position of the light source forms a convex polygon structure;

[0033] The first receiving unit includes a first converging lens, a first four-quadrant photodetector, and four identical first transimpedance amplifiers, wherein the optical axis of the first converging lens is perpendicular to the photosensitive surface of the first four-quadrant photodetector and passes through the center of the photosensitive surface of the first four-quadrant photodetector;

[0034] The second receiving unit includes a second converging lens, a second four-quadrant photodetector, and four identical second transimpedance amplifiers, wherein the optical axis of the second converging lens is perpendicular to the photosensitive surface of the second four-quadrant photodetector and passes through the center of the photosensitive surface of the second four-quadrant photodetector;

[0035] The first processing unit is used to cache the data information from the first communication data interface to obtain first cached data; divide the first cached data into multiple data segments of preset lengths according to a preset time sequence to obtain multiple first data segments; based on the half-duplex communication mode, according to the acquisition order of each first data segment, control one or more first light sources to emit optical signals to transmit each first data segment in the form of an optical signal from underwater to a second receiving unit on a second communication device, so that the second communication device determines the orientation information of the first communication device according to the received optical signal;

[0036] The second processing unit is used to cache the data information from the second communication data interface to obtain second cached data, and divide the second cached data into multiple data segments of preset lengths according to a preset time sequence to obtain multiple second data segments; based on the half-duplex communication mode, according to the acquisition order of each second data segment, control one or more second light sources to emit optical signals to transmit each second data segment in the form of an optical signal from underwater to the first receiving unit on the first communication device, so that the first communication device determines the orientation information of the second communication device according to the received optical signal.

[0037] It should be noted that the half-duplex communication mode means that the information transmission of two communication devices is periodically time-sharing, that is, when the first transmitting unit and the second receiving unit are working normally, the first receiving unit and the second transmitting unit are not working, and the information can only be transmitted from the first communication device to the second communication device; when the second transmitting unit and the first receiving unit are working normally, the second receiving unit and the first transmitting unit are not working, and the information can only be transmitted from the second communication device to the first communication device. When switching between the above two working modes, a certain amount of free time needs to be reserved as a protection time slot, and at this time, the first transmitting unit, the first receiving unit, the second transmitting unit, and the second receiving unit are all not working.

[0038] In order to ensure normal communication between the first communication device and the second communication device, it is necessary to pre-set the communication transmission rate, the link switching period of the half-duplex communication device, the length of time for the first communication device to transmit information to the second communication device within a time period, the length of time for the second communication device to transmit information to the first communication device within a time period, and the protection time slot length.

[0039] Optionally, the first communication device and the second communication device serve as a master device and a slave device respectively, or the first communication device and the second communication device serve as a slave device and a master device respectively to implement a half-duplex communication mode, wherein the master device is the initiator device of the communication process.

[0040] Further optionally, the first processing unit is specifically used to add first information to the first data segment to be transmitted to obtain a first transmission frame, and control one or more first light sources to emit light signals based on the first transmission frame, the first information includes a first data synchronization sequence, a first navigation synchronization sequence, and a first navigation mark sequence, the first data synchronization sequence and the first navigation synchronization sequence are preset binary sequences, the first data synchronization sequence is used to obtain time synchronization information and a starting position of the corresponding first data segment during transmission, the first navigation synchronization sequence is used to perform azimuth measurement of the first communication device, and the first navigation mark sequence is used to obtain time synchronization information and a starting position of the first navigation synchronization sequence during transmission;

[0041] The first receiving unit is specifically configured to convert the detected optical signal from the second communication device into four first voltage signals, represented by U 11 , U 12 , U 13 and U 14 and outputting each first voltage signal to a first processing unit;

[0042] The first processing unit is further used to obtain the position information of the second communication device and the second data segment transmitted by the second communication device according to each first voltage signal, and output the second data segment transmitted by the second communication device from the first communication data interface, and output the position information of the second communication device from the first position data interface;

[0043] a second processing unit, specifically used to add second information to a second data segment to be transmitted, obtain a second transmission frame, and control one or more second light sources to transmit an optical signal based on the second transmission frame, wherein the second information includes a second data synchronization sequence, a second navigation synchronization sequence, and a second navigation mark sequence, wherein the second data synchronization sequence and the second navigation synchronization sequence are preset binary sequences, wherein the second data synchronization sequence is used to obtain time synchronization information and a starting position of the corresponding second data segment during transmission, the second navigation synchronization sequence is used to perform azimuth measurement of the second communication device, and the second navigation mark sequence is used to obtain time synchronization information and a starting position of the second navigation synchronization sequence during transmission;

[0044] The second receiving unit is specifically configured to convert the detected optical signal from the first communication device into four second voltage signals, represented by U 21 , U 22 , U 23 and U 24 and outputting each second voltage signal to a second processing unit;

[0045] The second processing unit is also used to obtain the orientation information of the first communication device and the first data segment transmitted by the first communication device according to each second voltage signal, and output the first data segment transmitted by the first communication device from the second communication data interface, and output the orientation information of the first communication device from the second orientation data interface.

[0046] The two communication devices in the underwater wireless optical communication and azimuth measurement integrated system provided by the present invention can measure each other's azimuth information while realizing bidirectional data transmission, without the need for additional auxiliary equipment, thereby greatly reducing the complexity of the communication process.

[0047] Further optionally, the first processing unit is specifically used to perform error correction coding on the first data segment to be transmitted according to a preset error correction coding method to obtain the encoded first data segment; encode the position of each first light source to obtain four first position marks, represented as A1, B1, C1, and D1, and splice the first position marks in a preset order to obtain a first navigation mark sequence; sequentially splice the first data synchronization sequence, the encoded first data segment, the first navigation synchronization sequence, and the first navigation mark sequence together to form a first transmission frame; and control one or more first light sources to emit light signals according to the first transmission frame;

[0048] The second processing unit is specifically used to perform error correction coding on the second data segment to be transmitted according to a preset error correction coding method to obtain the encoded second data segment; encode the position of each second light source to obtain 4 second position marks, represented as A2, B2, C2, and D2, and splice each second position mark in a preset order to obtain a second navigation mark sequence; splice the second data synchronization sequence, the encoded second data segment, the second navigation synchronization sequence, and the second navigation mark sequence together in sequence to form a second transmission frame; and control one or more second light sources to emit light signals according to the second transmission frame.

[0049] Specifically, the first processing unit is specifically configured to control the corresponding first light source in the first transmitting unit to transmit a light signal according to the position mark in the first navigation sequence when the data information in the first transmission frame is the first navigation sequence; and control all the first light sources in the first transmitting unit to transmit a light signal when the data information in the first transmission frame is not the first navigation sequence;

[0050] The second processing unit is specifically used to control the corresponding second light sources in the second transmitting unit to emit light signals according to the position mark in the second navigation sequence when the data information in the second transmission frame is the second navigation sequence; and to control all the second light sources in the second transmitting unit to emit light signals when the data information in the second transmission frame is not the second navigation sequence.

[0051] When the transmitting unit in the communication equipment of the underwater wireless optical communication and azimuth measurement integrated system provided by the present invention transmits navigation data, the light sources in the transmitting unit work in time-sharing mode, and each light source is characterized by a different coding sequence, which can eliminate mutual interference between the light sources, so that the receiving unit can significantly distinguish the light signals emitted by the light sources when detecting them, thereby improving the reliability of the system.

[0052] Further optionally, the first receiving unit is specifically configured to converge the optical signal from the second communication device to the photosensitive surface of the first four-quadrant photodetector through a first converging lens to form a first light spot;

[0053] The first four-quadrant photoelectric detector is used to convert the first light spot into four first current signals, represented by I 11 ,I 12 ,I 13 ,I 14 ;

[0054] Each first transimpedance amplifier is used to convert the corresponding first current signal into a first voltage signal, and output each first voltage signal to the first processing unit;

[0055] A second receiving unit, specifically configured to converge the optical signal from the first communication device to the photosensitive surface of the second four-quadrant photodetector through a second converging lens to form a second light spot;

[0056] The second four-quadrant photodetector is used to convert the second light spot into four second current signals, represented by I 21 ,I 22 ,I 23 ,I 24 ;

[0057] Each second transimpedance amplifier is used to convert the corresponding second voltage signal into a second voltage signal, and output each second voltage signal to the second processing unit.

[0058] The underwater wireless optical communication and azimuth measurement integrated system provided by the present invention can be used in underwater small-angle laser communication as well as in underwater wide-angle emission systems when using a four-quadrant photoelectric detector to measure the azimuth of a cooperative target. It has wide practicability and can measure the distance and pointing information of the cooperative target at the same time.

[0059] Further optional,

[0060] The first processing unit is specifically used to identify each first voltage signal, and use the voltage signal with the highest amplitude to restore the second transmission frame; determine the encoded second data segment and the second navigation mark sequence according to the restored second transmission frame, the second data synchronization sequence and the second navigation synchronization sequence; perform error correction decoding on the encoded second data segment according to a preset error correction coding method to obtain the second data segment; identify the second light source in the second transmitting unit according to the generation method of the second navigation mark sequence, and find the first voltage average amplitude detected by the first receiving unit when each second light source emits light according to each first voltage signal; calculate the position coordinates of the light spot formed by each second light source on the photosensitive surface of the first four-quadrant photoelectric detector according to the working principle of the four-quadrant photoelectric detector and the average amplitude of each first voltage; calculate the position coordinates of the light spot formed by each second light source on the photosensitive surface of the first four-quadrant photoelectric detector according to the shape of each second light source on the photosensitive surface of the first four-quadrant photoelectric detector The position coordinates of the light spot formed, the vertical distance between the first converging lens and the first four-quadrant photodetector, determine the unit vector of each second light source relative to the coordinate origin O1, the coordinate system to which the coordinate origin O1 belongs is the coordinate system O1-X1Y1Z1 established with the center O1 of the first converging lens as the origin and the optical axis direction of the first converging lens as the Z1 axis direction; according to the unit vector corresponding to each second light source, determine the vertex angle corresponding to each second light source; according to the vertex angle corresponding to each second light source and the distance between each second light source, determine the length between the center O1 of the first converging lens and each second light source; according to the length between the center O1 of the first converging lens and each second light source, determine the coordinates of each second light source in the coordinate system O1-X1Y1Z1, and according to the coordinates of each second light source, determine the orientation information of the second communication device, and the corresponding expression is:

[0061]

[0062]

[0063] Where i = 1, 2, 3, 4, represents the unit vector of the i-th second light source relative to the coordinate origin O1, (x 1i ,y 1i) represents the position coordinates of the light spot formed by the i-th second light source on the photosensitive surface of the first four-quadrant photodetector when the coordinate system is established with the center of the photosensitive surface of the first four-quadrant photodetector as the origin, l1 represents the vertical distance between the first converging lens and the first four-quadrant photodetector; ∠A2O1B2, ∠B2O1C2, ∠C2O1D2, ∠D2O1A2∠A2O1C2 and ∠B2O1D2 represent the vertex angles of the four-sided pyramid formed by the center O1 of the first converging lens and the second light sources, A2B2, B2C2, C2D2, D2A2, A2C2, B2D2 represent the distances between the second light sources respectively, O1A2, O1B2, O1C2, O1D2 represent the lengths between the center O1 of the first converging lens and the second light sources respectively; M 11 、M 12 、M 13 、M 14 Respectively represent the coordinates of each second light source.

[0064] The second processing unit is specifically used to identify each second voltage signal, and use the voltage signal with the highest amplitude to restore the first transmission frame; determine the encoded first data segment and the first navigation mark sequence according to the restored first transmission frame, the first data synchronization sequence and the first navigation synchronization sequence; perform error correction decoding on the encoded first data segment according to a preset error correction coding method to obtain the first data segment; identify the first light source in the first transmitting unit according to the generation method of the first navigation mark sequence, and find the second voltage average amplitude detected by the second receiving unit when each first light source emits light according to each second voltage signal; calculate the light spot position coordinates formed by each first light source on the photosensitive surface of the second quadrant photodetector according to the working principle of the four-quadrant photodetector and the second voltage average amplitude; calculate the light spot position coordinates formed by each first light source on the photosensitive surface of the second quadrant photodetector according to the second voltage average amplitude; The formed light spot position coordinates, the vertical distance between the second converging lens and the second four-quadrant photodetector, determine the unit vector of each first light source relative to the coordinate origin O2, the coordinate system to which the coordinate origin O2 belongs is the coordinate system O2-X2Y2Z2 established with the center O2 of the second converging lens as the origin and the optical axis direction of the second converging lens as the Z2 axis direction; according to the unit vector corresponding to each first light source, determine the vertex angle corresponding to each first light source; according to the vertex angle corresponding to each first light source and the distance between each first light source, determine the length between the center O2 of the second converging lens and each first light source; according to the length between the center O2 of the second converging lens and each first light source, determine the coordinates of each first light source in the coordinate system O2-X2Y2Z2, and according to the coordinates of each first light source, determine the orientation information of the first communication device, and the corresponding expression is:

[0065]

[0066] Where j = 1, 2, 3, 4, represents the unit vector of the jth first light source relative to the coordinate origin O2, (x 2j ,y 2j ) represents the coordinates of the spot position formed by the jth first light source on the photosensitive surface of the second four-quadrant photodetector when the coordinate system is established with the center of the photosensitive surface of the second four-quadrant photodetector as the origin, l2 represents the vertical distance between the second converging lens and the second four-quadrant photodetector, ∠A1O2B1, ∠B1O2C1, ∠C1O2D1, ∠D1O2A1, ∠A1O2C1 and ∠B1O2D1 represent the vertex angles of the quadrangular pyramid formed by the center O2 of the second converging lens and the first light sources, A1B1, B1C1, C1D1, D1A1, A1C1 and B1D1 represent the distances between the first light sources, O2A1, O2B1, O2C1 and O2D1 represent the lengths between the center O2 of the second converging lens and the first light sources, M 21 、M 22 、M 23 、M 24 Respectively represent the coordinates of each first light source.

[0067] The integrated underwater wireless optical communication and azimuth measurement system provided by the present invention adopts a half-duplex communication mode to realize bidirectional data transmission. All optical signals in the two transmission directions of communication can use the same wavelength or different wavelengths, which greatly increases the flexibility of the design. Compared with the traditional underwater wireless optical communication system, only the light source layout and the photoelectric detector type have changed at the hardware level. Therefore, it has strong portability and is easy to promote and apply.

[0068] The present invention also provides an underwater wireless optical communication and azimuth measurement integrated method, which can be applied to any underwater wireless optical communication and azimuth measurement integrated system provided by the present invention, such as Figure 2 As shown, the method includes:

[0069] S1. A first communication device and a second communication device establish a transmission link in a half-duplex communication mode based on preset communication parameters.

[0070] Among them, the communication parameters include: the communication transmission rate between the first communication device and the second communication device, the link switching period of the half-duplex communication device, the length of time for the first communication device to transmit information to the second communication device within a time period, the length of time for the second communication device to transmit information to the first communication device within a time period, and the length of the protection time slot.

[0071] Optionally, step S1 includes the following steps s11-s15:

[0072] s11. Turn on the first transmitting unit, the first receiving unit, and the first processing unit in the first communication device, and the second receiving unit and the second processing unit in the second communication device.

[0073] s12. All the first light sources in the first transmitting unit emit light simultaneously, and transmit a certain sequence of light signals into the water as a link establishment signal.

[0074] s13. When the second receiving unit detects the link establishment signal, it turns on the second transmitting unit and sends a certain sequence of optical signals into the water as a response signal.

[0075] s14. When the first receiving unit detects the response signal, it continues to transmit the link establishment signal into the water through the first transmitting unit.

[0076] s15. Repeat steps s11-s14 until the second communication device and the first communication device respectively receive N times (N≧1, and is an integer) of link establishment signals and response signals in succession to establish a two-way communication link between the first communication device and the second communication device, and the two devices operate according to preset parameters such as the communication transmission rate, the link switching period of the half-duplex communication device, the time length for the first communication device to transmit information to the second communication device within a time period, the time length for the second communication device to transmit information to the first communication device within a time period, and the length of the protection time slot.

[0077] S2. The first processing unit caches the data information from the first communication data interface to obtain first cache data; the second processing unit caches the data information from the second communication data interface to obtain second cache data.

[0078] Among them, the data information from the first communication data interface is the data that needs to be transmitted from the first communication device to the second communication device; the data information from the second communication data interface is the data that needs to be transmitted from the second communication device to the first communication device, and the specific content of the data can be set according to actual conditions.

[0079] S3. The first processing unit divides the first cache data into multiple data segments of preset length according to a preset time sequence to obtain multiple first data segments; the second processing unit divides the second cache data into multiple data segments of preset length according to a preset time sequence to obtain multiple second data segments.

[0080] S4. Based on the half-duplex communication mode, the first communication device controls one or more first light sources to emit light signals according to the acquisition order of each first data segment, so as to transmit each first data segment from underwater to the second communication device in the form of an optical signal, so that the second communication device determines the position information of the first communication device according to the received optical signal; the second communication device controls one or more second light sources to emit light signals based on the acquisition order of each second data segment, so as to transmit each second data segment from underwater to the first communication device in the form of an optical signal, so that the first communication device determines the position information of the second communication device according to the received optical signal.

[0081] In a possible implementation, the first communication device controls one or more first light sources to emit light signals based on the acquisition order of each first data segment, including: a first processing unit adds first information to the first data segment to be transmitted to obtain a first transmission frame, and controls one or more first light sources to emit light signals based on the first transmission frame, the first information includes a first data synchronization sequence, a first navigation synchronization sequence, and a first navigation mark sequence, the first data synchronization sequence and the first navigation synchronization sequence are preset binary sequences, the first data synchronization sequence is used to obtain the time synchronization information and the starting position of the corresponding first data segment during transmission, the first navigation synchronization sequence is used to perform azimuth measurement of the first communication device, and the first navigation mark sequence is used to obtain the time synchronization information and the starting position of the first navigation synchronization sequence during transmission. In a possible implementation, the first communication device determines the azimuth information of the second communication device according to the received light signal, including: a first receiving unit converts the detected light signal from the second communication device into four first voltage signals, represented as U 11 , U 12 , U 13 and U 14 and outputs each first voltage signal to the first processing unit; the first processing unit obtains the position information of the second communication device and the second data segment transmitted by the second communication device according to each first voltage signal, and outputs the second data segment transmitted by the second communication device from the first communication data interface, and outputs the position information of the second communication device from the first position data interface for use by other applications;

[0082] In a possible implementation, the second communication device controls one or more second light sources to transmit light signals based on the acquisition order of each second data segment, including: the second processing unit adds second information to the second data segment to be transmitted to obtain a second transmission frame, and controls one or more second light sources to transmit light signals based on the second transmission frame, the second information includes a second data synchronization sequence, a second navigation synchronization sequence, and a second navigation mark sequence, the second data synchronization sequence and the second navigation synchronization sequence are preset binary sequences, the second data synchronization sequence is used to obtain time synchronization information of the corresponding second data segment during transmission, the second navigation synchronization sequence is used to perform azimuth measurement of the second communication device, and the second navigation mark sequence is used to obtain time synchronization information and a starting position of the second navigation synchronization sequence during transmission;

[0083] In a possible implementation, the second communication device determines the position information of the first communication device according to the received optical signal, including: the second receiving unit converts the detected optical signal from the first communication device into four second voltage signals, represented as U 21 , U 22 , U 23 and U 24 , and outputs each second voltage signal to the second processing unit; the second processing unit obtains the orientation information of the first communication device and the first data segment transmitted by the first communication device according to each second voltage signal, and outputs the first data segment transmitted by the first communication device from the second communication data interface, and outputs the orientation information of the first communication device from the second orientation data interface for use by other applications.

[0084] Further optionally, the first processing unit adds the first information to the first data segment to be transmitted to obtain the first transmission frame, and controls one or more first light sources to emit light signals based on the first transmission frame, including: the first processing unit performs error correction coding on the first data segment to be transmitted according to a preset error correction coding method to obtain the encoded first data segment; encodes the position of each first light source to obtain 4 first position marks, represented as A1, B1, C1, and D1, and splices each first position mark in a preset order to obtain a first navigation mark sequence; sequentially splices the first data synchronization sequence, the encoded first data segment, the first navigation synchronization sequence, and the first navigation mark sequence together to form a first transmission frame; when the data information in the first transmission frame is the first navigation mark sequence, the corresponding first light source in the first transmitting unit is controlled to generate a light signal according to the position mark in the first navigation mark sequence, and when the data information in the transmission frame is not the first navigation mark sequence, all the first light sources in the first transmitting unit are controlled to generate light signals.

[0085] Specifically, the position marker is a binary sequence.

[0086] Further optionally, the second processing unit adds second information to the second data segment to be transmitted to obtain a second transmission frame, and controls one or more second light sources to transmit light signals based on the second transmission frame, including:

[0087] The second processing unit performs error correction coding on the second data segment to be transmitted according to a preset error correction coding method to obtain an encoded second data segment; encodes the position of each second light source to obtain four second position marks, represented as A2, B2, C2, and D2, and splices each second position mark in a preset order to obtain a second navigation mark sequence; sequentially splices the second data synchronization sequence, the encoded second data segment, the second navigation synchronization sequence, and the second navigation mark sequence together to form a second transmission frame; when the data information in the second transmission frame is the second navigation mark sequence, the corresponding second light source in the second transmitting unit is controlled to generate a light signal according to the position mark in the second navigation mark sequence, and when the data information in the transmission frame is not the second navigation mark sequence, all the second light sources in the second transmitting unit are controlled to generate light signals.

[0088] Optionally, the first receiving unit converts the detected optical signal from the second communication device into four first voltage signals, represented by U 11 , U 12 , U 13 and U 14 , and outputs each first voltage signal to the first processing unit, including: the first receiving unit converges the optical signal from the second communication device to the photosensitive surface of the first four-quadrant photodetector through the first converging lens to form a first light spot; converts the first light spot into four first current signals through the first four-quadrant photodetector, represented by I 11 ,I 12 ,I 13 ,I 14 ; Each first current signal is converted into a first voltage signal through each first transimpedance amplifier and output to the first processing unit.

[0089] Optionally, the second receiving unit converts the detected optical signal from the first communication device into four second voltage signals, represented by U 21 , U 22 , U 23 and U 24 , and outputs each second voltage signal to the second processing unit, including: the second receiving unit converges the optical signal from the first communication device to the photosensitive surface of the second four-quadrant photodetector through the second converging lens to form a second light spot; the second receiving unit converts the second light spot into four second current signals through the second four-quadrant photodetector, represented by I 21 ,I 22 ,I 23 ,I24 ; Each second voltage signal is converted into a second voltage signal through each second transimpedance amplifier and output to the second processing unit.

[0090] Optionally, the first processing unit obtains the position information of the second communication device and the second data segment transmitted by the second communication device according to each first voltage signal, including the following steps A1-A10:

[0091] A1. The first processing unit identifies each first voltage signal and uses the voltage signal with the highest amplitude to restore the second transmission frame.

[0092] A2. The first processing unit determines the encoded second data segment and the second navigation mark sequence according to the restored second transmission frame, the second data synchronization sequence and the second navigation synchronization sequence.

[0093] A3. The first processing unit performs error correction decoding on the encoded second data segment according to a preset error correction coding method to obtain a second data segment.

[0094] A4. The first processing unit identifies the second light source in the second transmitting unit according to the generation method of the second navigation mark sequence, and searches for the average amplitude of the first voltage detected by the first receiving unit when each second light source emits light according to each first voltage signal.

[0095] A5. The first processing unit calculates the position coordinates of the light spots formed by each second light source on the surface of the first four-quadrant photodetector according to the working principle of the four-quadrant photodetector and the average amplitude of each first voltage.

[0096] The corresponding coordinate system is a coordinate system established with the center of the photosensitive surface of the first four-quadrant photoelectric detector as the origin.

[0097] A6. In the first communication device, based on the position coordinates of the light spots formed by each second light source on the photosensitive surface of the first four-quadrant photodetector and the vertical distance between the first converging lens and the first four-quadrant photodetector, the unit vector of each second light source relative to the coordinate origin O1 is determined, expressed as:

[0098]

[0099] The coordinate system to which the coordinate origin O1 belongs is a coordinate system O1-X1Y1Z1 established with the center O1 of the first converging lens as the origin and the optical axis direction of the first converging lens as the Z1 axis direction, i=1,2,3,4, is the unit vector of the i-th second light source relative to the coordinate origin O1, (x 1i ,y 1i) represents the position coordinates of the light spot formed by the ith second light source on the photosensitive surface of the first four-quadrant photodetector when the coordinate system is established with the center of the photosensitive surface of the first four-quadrant photodetector as the origin, and l1 represents the vertical distance between the first converging lens and the first four-quadrant photodetector.

[0100] A7. The first communication device determines the vertex angle corresponding to each second light source according to the unit vector corresponding to each second light source, expressed as:

[0101]

[0102] Among them, ∠A2O1B2, ∠B2O1C2, ∠C2O1D2, ∠D2O1A2∠A2O1C2 and ∠B2O1D2 represent the vertex angles of the quadrangular pyramid formed by the center O1 of the first four-image converging lens and the second light sources.

[0103] A8. The first processing unit determines the length between the center O1 of the first converging lens and each second light source according to the vertex angle corresponding to each second light source and the distance between each second light source, which is expressed as:

[0104]

[0105] Among them, A2B2, B2C2, C2D2, D2A2, A2C2, and B2D2 respectively represent the distances between each pair of second light sources, and O1A2, O1B2, O1C2, and O1D2 respectively represent the lengths between the center O1 of the first converging lens and each second light source.

[0106] A9. The first processing unit determines the coordinates of each second light source in the coordinate system O1-X1Y1Z1 according to the length between the center O1 of the first converging lens and each second light source, expressed as:

[0107]

[0108] Among them, M 11 、M 12 、M 13 、M 14 The coordinates of each second light source are respectively represented, and the orientation information of the second communication device is determined according to the coordinates of each second light source.

[0109] A10. Determine the orientation information of the second communication device according to the coordinates of each second light source.

[0110] Optionally, the second processing unit obtains the position information of the first communication device and the first data segment transmitted by the first communication device according to each second voltage signal, including the following steps B1-B10:

[0111] B1. The second processing unit identifies each second voltage signal and uses the voltage signal with the highest amplitude to restore the first transmission frame.

[0112] B2. The second processing unit determines and distinguishes the encoded first data segment and the first navigation mark sequence according to the restored first transmission frame, the first data synchronization sequence and the first navigation synchronization sequence.

[0113] B3. The second processing unit performs error correction decoding on the encoded first data segment according to a preset error correction coding method to obtain the first data segment.

[0114] B4. The second processing unit identifies the first light source in the first transmitting unit according to the generation method of the first navigation mark sequence, and searches for the average amplitude of the second voltage detected by the second receiving unit when each first light source emits light according to each second voltage signal.

[0115] B5. The second processing unit calculates the coordinates of the light spot positions formed by each first light source on the photosensitive surface of the second four-quadrant photodetector according to the working principle of the four-quadrant photodetector and the average amplitude of the second voltage.

[0116] The corresponding coordinate system is a coordinate system established with the center of the photosensitive surface of the second four-quadrant photoelectric detector as the origin.

[0117] B6. The second processing unit determines the unit vector of each first light source relative to the coordinate origin O2 according to the coordinates of the light spot position formed by each first light source on the photosensitive surface of the second four-quadrant photodetector and the vertical distance between the second converging lens and the second four-quadrant photodetector, expressed as:

[0118]

[0119] The coordinate system to which the coordinate origin O2 belongs is a coordinate system O2-X2Y2Z2 established with the center O2 of the second converging lens as the origin and the optical axis direction of the second converging lens as the Z2 axis direction, j=1,2,3,4, represents the unit vector of the jth first light source relative to the coordinate origin O2, (x 2j ,y 2j ) represents the coordinates of the spot position formed by the jth first light source on the photosensitive surface of the second four-quadrant photodetector when the coordinate system is established with the center of the photosensitive surface of the second four-quadrant photodetector as the origin, and l2 represents the vertical distance between the second converging lens and the second four-quadrant photodetector.

[0120] B7. The second communication device determines the vertex angle corresponding to each first light source according to the unit vector corresponding to each first light source, expressed as:

[0121]

[0122] Among them, ∠A1O2B1, ∠B1O2C1, ∠C1O2D1, ∠D1O2A1, ∠A1O2C1 and ∠B1O2D1 represent the vertex angles of the quadrangular pyramid formed by the second converging lens center O2 and the first light sources.

[0123] B8. The second processing unit determines the length between the center O2 of the second converging lens and each first light source according to the vertex angle corresponding to each first light source and the distance between each first light source, which is expressed as:

[0124]

[0125] Among them, A1B1, B1C1, C1D1, D1A1, A1C1, and B1D1 respectively represent the distances between each pair of first light sources, and O2A1, O2B1, O2C1, and O2D1 respectively represent the lengths between the center O2 of the second converging lens and each first light source.

[0126] B9. The second processing unit determines the coordinates of each first light source in the coordinate system O2-X2Y2Z2 according to the length between the center O2 of the second converging lens and each first light source, expressed as:

[0127]

[0128] Among them, M 21 、M 22 、M 23 、M 24 Respectively represent the coordinates of each first light source.

[0129] B10. Determine the orientation information of the first communication device according to the coordinates of each first light source.

[0130] In order to further demonstrate the beneficial effects of the present invention, the present invention also provides a group of simulation experiments.

[0131] Figure 3 A schematic diagram of an experimental verification system for an underwater wireless optical communication and azimuth measurement integrated system provided by the present invention. Figure 4 is a schematic diagram of a data transmission mode of a half-duplex communication within one cycle provided by the present invention, Figure 5 A schematic diagram of a model for detecting the orientation of a light source array using a four-quadrant detector provided by the present invention; Figures 3 to 5 As shown, the experimental verification system is composed of a first communication device, a second communication device, computer 1#, computer 2#, turntable 1#, and turntable 2#.

[0132] The first communication device is installed on turntable 1# and placed in water. It consists of a first transmitting unit, a first receiving unit, and a first processing unit. The first transmitting unit consists of four light-emitting diode light sources with a central wavelength of 470nm and a spectral width of 30nm, respectively marked as light source A1, light source B1, light source C1, and light source D1. The four light sources are distributed in the same plane to form a square with a side length of 30cm. The first transmitting unit modulates each light source to independently transmit a light signal according to the control voltage output by the first processing unit, generates a first light signal and transmits it into the water; the first receiving unit consists of a converging lens 1# and a four-quadrant photodetector module 1#, which are used to receive the second light signal; the optical axis of lens 1# is perpendicular to the photosensitive surface of the four-quadrant photodetector module 1# and passes through its center. After passing through the converging lens, the second light signal converges on the photosensitive surface of the four-quadrant photodetector module 1# to form a light spot, and converts and outputs four current signals , converted into 4 voltage signals through 4 identical transimpedance amplifiers built into the four-quadrant photodetector module 1# and output to the first processing unit, and the effective receiving field of view of the first receiving unit is about ±4°; the first processing unit is a circuit board made based on Xilinx's Zynq7035, and generates 4 control voltages according to the data information input by the first communication data interface, which are respectively used to modulate the light source in the first transmitting unit to generate an optical signal, and obtains the data information from the second communication device and the azimuth information of the second communication device according to the four voltage signals input by the first receiving unit, and outputs them through the first communication data interface and the first azimuth data interface respectively, wherein the first communication data interface is a network port based on the TCP / IP protocol, and the first azimuth data interface is a serial port.

[0133] The second communication device is installed on turntable 2# and placed in the water. It consists of a second transmitting unit, a second receiving unit, and a second processing unit. The second transmitting unit consists of four light-emitting diode light sources with a central wavelength of 470nm and a spectral width of 30nm, respectively marked as light source A2, light source B2, light source C2, and light source D2. The four light sources are distributed in the same plane to form a square with a side length of 30cm. The second transmitting unit modulates each light source to independently transmit a light signal according to the control voltage output by the second processing unit, generates a second light signal and transmits it into the water; the second receiving unit consists of a converging lens 2# and a four-quadrant photodetector module 2#, which are used to receive the first light signal. The optical axis of lens 2# is perpendicular to the photosensitive surface of the four-quadrant photodetector module 2# and passes through its center. After passing through the converging lens, the first light signal converges on the photosensitive surface of the four-quadrant photodetector module 2# to form a light spot, and converts and outputs four current signals , converted into 4 voltage signals through 4 identical transimpedance amplifiers built into the four-quadrant photodetector module 2# and output to the second processing unit, and the effective receiving field of the second receiving unit is about ±4°; the second processing unit is a circuit board made based on Xilinx's Zynq7035, and generates 4 control voltages according to the data information input by the second communication data interface, which are respectively used to modulate the light source in the second transmitting unit to generate optical signals, and obtains data information from the first communication device and the azimuth information of the first communication device according to the four voltage signals input by the second receiving unit, and outputs them through the second communication data interface and the second azimuth data interface respectively, wherein the second communication data interface is a network port based on the TCP / IP protocol, and the second azimuth data interface is a serial port.

[0134] The first communication device and the second communication device operate in a half-duplex communication mode, and information transmission between the two communication devices operates in a periodic time-sharing manner. When the first communication unit and the second receiving unit operate normally, the first receiving unit and the second transmitting unit do not operate, and at this time, information can only be transmitted from the first communication device to the second communication device; when the second communication unit and the first receiving unit operate normally, the second receiving unit and the first transmitting unit do not operate, and at this time, information can only be transmitted from the second communication device to the first communication device; when the above two operating modes are switched, a certain amount of spare time is reserved as a protection time slot, and at this time, the first communication unit, the first receiving unit, the second communication unit, and the second receiving unit do not operate; and the communication transmission rate is pre-set to 12.5Mbps, the link switching period of the half-duplex communication device is 100ms, the time length of the first communication device to transmit information to the second communication device within a time period is 50ms, the time length of the second communication device to transmit information to the first communication device within a time period is 50ms, and the protection time slot length is 0.

[0135] The first communication device and the second communication device respectively implement a half-duplex communication mode as a master device and a slave device, and the master device is the initiator device of the communication process;

[0136] Computer 1# is connected to the first communication device via a watertight cable, and uses the first communication data interface to send and receive data to the first communication device via the TCP / IP protocol, and is used to receive and display the position information of the second communication device from the first position data interface;

[0137] Computer 2# is connected to the second communication device via a watertight cable, and uses the second communication data interface to send and receive data to the second communication device via the TCP / IP protocol, so as to receive and display the position information of the first communication device from the second position data interface;

[0138] Turntable 1# and turntable 2# can rotate horizontally to simulate different orientations of the first communication device and the second communication device. The distance between the first communication device and the second communication device can be adjusted according to experimental requirements.

[0139] Choose clean tap water to simulate the water environment for the experiment, such as Figure 4 As shown, take the following steps:

[0140] Step 1: pre-set the communication transmission rate to 12.5Mbps, the link switching period of the half-duplex communication device to 100ms, the time length for the first communication device to transmit information to the second communication device within a time period to 50ms, the time length for the second communication device to transmit information to the first communication device within a time period to 50ms, and the length of the protection time slot to 0; turn on the first transmitting unit, the first receiving unit, and the first processing unit in the first communication device, and the second receiving unit and the second processing unit in the second communication device; the first processing unit controls the light source array in the first transmitting unit to emit light simultaneously, and emits a certain sequence of first communication light signals into the water as a link establishment signal; when the second receiving unit of the second communication device detects When a link establishment signal is received, the second transmitting unit is turned on to send a second communication optical signal into the water as a response signal; when the first receiving unit in the first communication device detects the response signal, the link establishment signal transmitted into the water through the first transmitting unit continues; when the second communication device and the first communication device respectively receive the preset 5 link establishment signals and response signals in succession, it indicates that a two-way communication link between the two communication devices has been established, and the two devices work according to the preset communication transmission rate, the link switching period of the half-duplex communication device, the length of time for the first communication device to transmit information to the second communication device within a time period, the length of time for the second communication device to transmit information to the first communication device within a time period, the length of the protection time slot and other parameters.

[0141] Step 2: When the transmission link is established, the first processing unit in the first communication device caches the data information from the first communication data interface to obtain first cached data; the second processing unit in the second communication device caches the data information from the second communication data interface to obtain second cached data.

[0142] Step three: the first processing unit in the first communication device divides the first cache data of step two into multiple data segments with preset lengths according to a preset time sequence, and each data segment is called a first data segment; the second processing unit in the second communication device divides the second cache data of step two into multiple data segments with preset lengths according to a preset time sequence, and each data segment is called a second data segment; the time length of the first data segment and the second data segment does not exceed 30ms.

[0143] Step 4: The first processing unit performs error correction coding on the first data frame according to a preset Reed-Solomon codes (RS) error correction coding to obtain an encoded first data segment; the second processing unit performs error correction coding on the second data frame according to the same coding method to obtain an encoded second data segment; the lengths of the encoded first data segment and the second data segment do not exceed 38ms; in the first processing unit, the light source A1, light source B1, light source C1, and light source D1 in the first transmitting unit are encoded with 2ms of continuous "11000011", 2ms of continuous "11010111", 2ms of continuous "11011011", and 2ms of continuous "11101011", respectively, the position of each light source is marked by coding, and the marked 4 binary sequences are encoded according to The four light sources are spliced ​​together in a preset order to form a first navigation mark sequence. The four light sources form a convex quadrilateral in space, and their position centers are marked as A1, B1, C1, and D1 respectively. In the second processing unit, the light source A2, light source B2, light source C2, and light source D2 in the second transmitting unit are marked with 2ms of continuous "11100011", 2ms of continuous "11110111", 2ms of continuous "11111011", and 2ms of continuous "11111011", respectively, and the marked four binary sequences are spliced ​​together in a preset order to form a second navigation mark sequence. The four light sources form a convex quadrilateral in space, and their position centers are marked as A2, B2, C2, and D2 respectively.

[0144] In the first processing unit, the preset 2ms continuous "10101011" and 2ms continuous "10101001" are used as the first data synchronization sequence and the first navigation synchronization sequence respectively; in the second processing unit, the preset 2ms continuous "10011011" and 2ms continuous "10011001" are used as the second data synchronization sequence and the second navigation synchronization sequence respectively.

[0145] In the first processing unit, the first data synchronization sequence, the encoded first data segment, the first navigation synchronization sequence, and the first navigation mark sequence are spliced ​​together in sequence, and the time occupied by the four is 2ms, 38ms, 2ms, and 8ms respectively, to form a first transmission frame; in the second processing unit, the second data synchronization sequence, the encoded second data segment, the second navigation synchronization sequence, and the second navigation mark sequence are spliced ​​together in sequence, and the time occupied by the four is 2ms, 38ms, 2ms, and 8ms respectively, to form a second transmission frame.

[0146] The first processing unit identifies the information in the first transmission frame, and when identifying the first navigation mark sequence of the first transmission frame, only modulates the light source in the first transmitting unit corresponding to the navigation mark in the sequence (i.e., the position mark corresponding to the light source) to generate the first light signal, otherwise all the light sources emit light simultaneously to generate the first light signal; the second processing unit identifies the information in the second transmission frame, and when identifying the second navigation mark sequence of the second transmission frame, only modulates the light source in the second transmitting unit corresponding to the navigation mark in the sequence to generate the first light signal, otherwise all the light sources emit light simultaneously to generate the first light signal.

[0147] Step 5: The second light signal enters the first receiving unit and is converged by lens 1# in the first receiving unit to the photosensitive surface of the four-quadrant photodetector module 1#, forming a first light spot; the first light signal enters the second receiving unit and is converged by lens 2# in the second receiving unit to the photosensitive surface of the four-quadrant photodetector module 2#, forming a second light spot.

[0148] The four-quadrant photoelectric detector module 1# in the first receiving unit converts the first light spot into four current signals I 11 ,I 12 ,I 13 ,I 14 Output, and converted into voltage signal U through built-in 4 identical transimpedance amplifiers 11 , U 12 , U 13 , U 14 Output to the first processing unit; the four-quadrant photodetector module 2# in the second receiving unit converts the second light spot into four-way current signal I 21 ,I 22 ,I23 ,I 24 Output, and converted into voltage signal U through built-in 4 identical transimpedance amplifiers 21 , U 22 , U 23 , U 24 Output to the second processing unit.

[0149] The first processing unit processes the voltage signal U 11 , U 12 , U 13 , U 14 The second processing unit performs identification and uses the voltage signal with the highest amplitude to restore the second transmission frame; the second processing unit processes the voltage signal U 21 , U 22 , U 23 , U 24 An identification is performed, and the voltage signal with the highest amplitude is used to restore the first transmission frame.

[0150] The first processing unit identifies the encoded second data segment and the second navigation mark sequence based on the second transmission frame, the second data synchronization sequence and the second navigation synchronization sequence; the second processing unit identifies the encoded first data segment and the first navigation mark sequence based on the first transmission frame, the first data synchronization sequence and the first navigation synchronization sequence.

[0151] The first processing unit performs error correction decoding on the encoded second data segment according to the error correction coding method to obtain the second data segment; the second processing unit performs error correction decoding on the encoded first data segment according to the error correction coding method to obtain the first data segment.

[0152] The first processing unit identifies four light sources preset in the second transmitting unit according to the generation method of the second navigation mark sequence, and 11 , U 12 , U 13 , U 14 When the corresponding light sources A2, B2, C2, and D2 emit light, the average voltage amplitude u detected by the first receiving unit is found 11i 、u 12i 、u 13i 、u 14i (i=1, 2, 3, 4); the second processing unit identifies the four light sources preset in the first transmitting unit according to the generation method of the first navigation mark sequence, and 21 , U 22 , U 23 , U 24 When the corresponding light sources A1, B1, C1, and D1 emit light, the average voltage amplitude u detected by the second receiving unit is found 21j 、u 22j 、u 23j 、u24j (j=1, 2, 3, 4).

[0153] The coordinate system is constructed with the center of the photosensitive surface of the four-quadrant photodetector module 1# in the first receiving unit as the coordinate origin. The first processing unit calculates the average voltage u 11i 、u 12i 、u 13i 、u 14i (i=1, 2, 3, 4), calculate the light spot position coordinates (x) formed by the four-quadrant photodetector module in the first receiving unit for each light source A2, B2, C2, D2 in the second transmitting unit 1i ,y 1i ), where K1 is the proportional coefficient constant; a coordinate system is constructed with the photosensitive center of the four-quadrant photodetector module 2# in the second receiving unit as the coordinate origin, and the second processing unit is based on the voltage average value u 21j 、u 22j 、u 23j 、u 24j (j=1, 2, 3, 4), calculate the light spot position coordinates (x) formed by each light source A1, B1, C1, D1 in the second transmitting unit at the center of the photosensitive surface of the four-quadrant photodetector module 2# in the first receiving unit 2j ,y 2j ), where K2 is the proportional coefficient constant;

[0154]

[0155] In the first communication device, the center O1 of the convergent lens "lens 1#" in the first receiving unit is taken as the origin, and the optical axis direction is taken as the Z1 axis direction to establish a coordinate system O1-X1Y1Z1. 1i ,y 1i )(i=1,2,3,4), combined with the vertical distance l1 between the converging lens and the four-quadrant photodetector in the first receiving unit, the unit vectors of the four light source positions A2, B2, C2, and D2 relative to O1 are obtained In the second communication device, the center O2 of the converging lens "lens 2#" in the second receiving unit is taken as the origin, and the optical axis direction is taken as the Z2 axis direction to establish a coordinate system O2-X2Y2Z2. 2j ,y 2j )(j=1,2,3,4), combined with the vertical distance l2 between the converging lens and the four-quadrant photodetector in the second receiving unit, the unit vectors of the four light source positions A1, B1, C1, and D1 relative to O2 are obtained

[0156] In the first communication device, the center O1 of the four-quadrant photoelectric detector of the first receiving unit and the centers of the four light sources A2, B2, C2, and D2 of the second transmitting unit form a quadrangular pyramid, ∠B2O1D2 according to The apex angles of the quadrangular pyramid are obtained as follows: ∠A2O1B2, ∠B2O1C2, ∠C2O1D2, ∠D2O1A2∠A2O1C2; in the second communication device, the center O2 of the four-quadrant photoelectric detector of the second receiving unit and the center of the four light source centers A1, B1, C1, and D1 of the first transmitting unit form a quadrangular pyramid. The vertex angles of the tetrahedron are obtained as ∠A1O2B1, ∠B1O2C1, ∠C1O2D1, ∠D1O2A1, ∠A1O2C1, and ∠B1O2D1.

[0157] In the first communication device, the first processing unit obtains the lengths O1A2, O1B2, O1C2, O1D2 between O1 and A2, B2, C2, D2 according to ∠A2O1B2, ∠B2O1C2, ∠C2O1D2, ∠D2O1A2∠A2O1C2, ∠B2O1D2 and the distances A2B2, B2C2, C2D2, D2A2, A2C2, B2D2 between A2, B2, C2, D2; In the second communication device, the second processing unit obtains the lengths O2A1, O2B1, O2C1, O2D1 between O2 and A1, B1, C1, D1 based on ∠A1O2B1, ∠B1O2C1, ∠C1O2D1, ∠D1O2A1, ∠A1O2C1, ∠B1O2D1 and the distances A1B1, B1C1, C1D1, D1A1, A1C1, B1D1 between A1, B1, C1, D1.

[0158] In the first communication device, the first processing unit obtains the coordinates M of A2, B2, C2, and D2 in the coordinate system O1-X1Y1Z1 according to the obtained sizes of O1A2, O1B2, O1C2, and O1D2. 11 、M 12 、M 13 、M 14 , and based on these four coordinates, the center coordinates of the plane where A2, B2, C2, and D2 are located are calculated to obtain their distance and direction angle relative to O1 as the orientation information of the second communication device; in the second communication device, the second processing unit obtains the coordinates M of A1, B1, C1, and D1 in the coordinate system O2-X2Y2Z2 according to the obtained degrees O2A1, O2B1, O2C1, and O2D1 21 、M 22 、M 23 、M 24, and based on these four coordinates, the center coordinates of the plane where A1, B1, C1, and D1 are located are calculated to obtain their distance and direction angle relative to O2 as the orientation information of the second communication device.

[0159] Utilizing the first processing unit of the first communication device, the second data segment is output from the first communication data interface, and the position information of the second communication device is output from the first position data interface; utilizing the second processing unit of the second communication device, the first data segment is output from the second communication data interface, and the position information of the first communication device is output from the second position data interface.

[0160] The first buffered data is transmitted from the first communication device to the second communication device in chronological order; and the second buffered data is transmitted from the second communication device to the first communication device.

[0161] In the experimental project, a two-way data transmission service is established by using the first communication device and the second communication device through the File Transfer Protocol (FTP) through computer 1# and computer 2#, so that the files in computer 1# can be transferred to computer 2# through the first communication device and the second communication device; so that the files in computer 2# can be transferred to computer 1# through the second communication device and the first communication device. And the first communication device and the second communication device are horizontally rotated by turntable 1# and turntable 2#. When the mutual angle of the communication devices is within the range of ±4°, it can be seen from computer 1# and computer 2# that the data transmission service is normal, which indicates that the communication system can perform data transmission. The first communication device and the second communication device are placed in the water with a distance of 3.8m between them. At the same time, according to the coordinates of the second communication device, the angle and distance information of the second communication device detected by the first communication device are displayed by computer 1#, as shown in Table 1; according to the coordinates of the first communication device, the angle and distance information of the first communication device detected by the second communication device are displayed by computer 2#, as shown in Table 2. It can be seen that the angle error is not greater than 0.3° and the distance error is not greater than 0.10m. These results verify the effectiveness of the method.

[0162] Table 1 Experimental results of the first communication device measuring the second communication device

[0163] Actual horizontal angle (unit: degree) Measurement level (unit: degree) Measuring distance (unit: meter) -4 -4.10 3.86 -3 -2.90 3.80 -2 -1.80 3.86 -1 -1.20 3.86 0 -0.20 3.85 1 0.70 3.83 2 1.80 3.86 3 2.84 3.77 4 3.77 3.76

[0164] Table 2 Experimental results of the second communication device measuring the first communication device

[0165] Actual horizontal angle (unit: degree) Measurement level (unit: degree) Measuring distance (unit: meter) -4 -4.08 3.85 -3 -2.95 3.87 -2 -1.85 3.86 -1 -1.10 3.86 0 -0.08 3.84 1 0.91 3.85 2 1.90 3.85 3 2.88 3.75 4 3.75 3.78

[0166] As for the method embodiment, since it is basically similar to the system embodiment, the description is relatively simple, and the specific contents and beneficial effects and other related matters can be referred to the partial description of the system embodiment.

[0167] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0168] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. An integrated underwater wireless optical communication and azimuth measurement system, characterized in that: include: A first communication device and a second communication device, wherein the working wavelengths of the first communication device and the second communication device are in the visible light band, and a half-duplex communication mode is adopted for bidirectional information transmission, a first communication data interface and a first azimuth data interface are provided on the first communication device, and a second communication data interface and a second azimuth data interface are provided on the second communication device; The first communication device includes a first transmitting unit, a first receiving unit, and a first processing unit; the first transmitting unit includes four first light sources, each of which is distributed on the same plane and the center position of the light source forms a convex polygon structure; The second communication device includes a second transmitting unit, a second receiving unit, and a second processing unit; the second transmitting unit includes four second light sources, each of which is distributed on the same plane and the center position of the light source forms a convex polygon structure; The first receiving unit comprises a first converging lens, a first four-quadrant photodetector, and four identical first transimpedance amplifiers, wherein the optical axis of the first converging lens is perpendicular to the photosensitive surface of the first four-quadrant photodetector and passes through the center of the photosensitive surface of the first four-quadrant photodetector; The second receiving unit comprises a second converging lens, a second four-quadrant photodetector, and four identical second transimpedance amplifiers, wherein the optical axis of the second converging lens is perpendicular to the photosensitive surface of the second four-quadrant photodetector and passes through the center of the photosensitive surface of the second four-quadrant photodetector; The first processing unit is used to cache the data information from the first communication data interface to obtain first cached data; divide the first cached data into multiple data segments of preset lengths according to a preset time sequence to obtain multiple first data segments; based on a half-duplex communication mode, according to the acquisition order of each first data segment, control one or more first light sources to emit optical signals, so as to transmit each first data segment in the form of an optical signal from underwater to the second receiving unit on the second communication device, so that the second communication device determines the orientation information of the first communication device according to the received optical signal; The second processing unit is used to cache the data information from the second communication data interface to obtain second cached data, and divide the second cached data into multiple data segments of preset lengths in a preset time sequence to obtain multiple second data segments; based on the half-duplex communication mode, according to the acquisition order of each second data segment, control one or more second light sources to emit optical signals to transmit each second data segment in the form of an optical signal from underwater to the first receiving unit on the first communication device, so that the first communication device determines the orientation information of the second communication device based on the received optical signal.

2. The system according to claim 1, characterized in that The first processing unit is specifically used to add first information to a first data segment to be transmitted to obtain a first transmission frame, and control one or more of the first light sources to transmit light signals based on the first transmission frame, wherein the first information includes a first data synchronization sequence, a first navigation synchronization sequence, and a first navigation mark sequence, wherein the first data synchronization sequence and the first navigation synchronization sequence are preset binary sequences, wherein the first data synchronization sequence is used to obtain time synchronization information and a starting position of the corresponding first data segment during transmission, the first navigation synchronization sequence is used to perform azimuth measurement of the first communication device, and the first navigation mark sequence is used to obtain time synchronization information and a starting position of the first navigation synchronization sequence during transmission; The first receiving unit is specifically configured to convert the detected optical signal from the second communication device into four first voltage signals, represented by U 11 , U 12 , U 13 and U 14 and outputting each of the first voltage signals to the first processing unit; The first processing unit is further used to obtain the position information of the second communication device and the second data segment transmitted by the second communication device according to each of the first voltage signals, and output the second data segment transmitted by the second communication device from the first communication data interface, and output the position information of the second communication device from the first position data interface; The second processing unit is specifically used to add second information to the second data segment to be transmitted to obtain a second transmission frame, and control one or more second light sources to transmit light signals based on the second transmission frame, wherein the second information includes a second data synchronization sequence, a second navigation synchronization sequence, and a second navigation mark sequence, wherein the second data synchronization sequence and the second navigation synchronization sequence are preset binary sequences, wherein the second data synchronization sequence is used to obtain time synchronization information and a starting position of the corresponding second data segment during transmission, the second navigation synchronization sequence is used to perform azimuth measurement of the second communication device, and the second navigation mark sequence is used to obtain time synchronization information and a starting position of the second navigation synchronization sequence during transmission; The second receiving unit is specifically configured to convert the detected optical signal from the first communication device into four second voltage signals, represented by U 21 , U 22 , U 23 and U 24 and outputting each of the second voltage signals to the second processing unit; The second processing unit is also used to obtain the orientation information of the first communication device and the first data segment transmitted by the first communication device according to each of the second voltage signals, and output the first data segment transmitted by the first communication device from the second communication data interface, and output the orientation information of the first communication device from the second orientation data interface.

3. The system according to claim 2, characterized in that The first processing unit is specifically used to perform error correction coding on the first data segment to be transmitted according to a preset error correction coding method to obtain an encoded first data segment; encode the position of each of the first light sources to obtain four first position marks, represented as A1, B1, C1, and D1, and splice each of the first position marks in a preset order to obtain a first navigation mark sequence; sequentially splice the first data synchronization sequence, the encoded first data segment, the first navigation synchronization sequence, and the first navigation mark sequence together to form the first transmission frame; and control one or more first light sources to emit light signals according to the first transmission frame; The second processing unit is specifically configured to perform error correction coding on the second data segment to be transmitted according to a preset error correction coding method to obtain an encoded second data segment; encode the position of each of the second light sources to obtain four second position marks, represented as A2, B2, C2, and D2, and splice each of the second position marks in a preset order to obtain a second navigation mark sequence; and sequentially splice the second data synchronization sequence, the encoded second data segment, the second navigation synchronization sequence, and the second navigation mark sequence together to form a second transmission frame; One or more second light sources are controlled to emit light signals according to the second transmission frame.

4. The system according to claim 3, characterized in that The first receiving unit is specifically configured to converge the optical signal from the second communication device to the photosensitive surface of the first four-quadrant photodetector through the first converging lens to form a first light spot; The first four-quadrant photodetector is used to convert the first light spot into four first current signals, represented by I 11 ,I 12 ,I 13 ,I 14 ; Each of the first transimpedance amplifiers is used to convert the corresponding first current signal into a first voltage signal, and output each of the first voltage signals to the first processing unit; The second receiving unit is specifically configured to converge the optical signal from the first communication device to the photosensitive surface of the second four-quadrant photodetector through the second converging lens to form a second light spot; The second four-quadrant photodetector is used to convert the second light spot into four second current signals, represented by I 21 ,I 22 ,I 23 ,I 24 ; Each of the second transimpedance amplifiers is used to convert the corresponding second voltage signal into a second voltage signal, and output each of the second voltage signals to the second processing unit.

5. The system according to claim 4, characterized in that The first processing unit is specifically used to identify each of the first voltage signals, and use the voltage signal with the highest amplitude to restore the second transmission frame; determine the encoded second data segment and the second navigation mark sequence according to the restored second transmission frame, the second data synchronization sequence and the second navigation synchronization sequence; perform error correction decoding on the encoded second data segment according to the preset error correction coding method to obtain the second data segment; According to the generation method of the second navigation mark sequence, the second light source in the second transmitting unit is identified, and according to each of the first voltage signals, the first voltage average amplitude detected by the first receiving unit when each of the second light sources emits light is found; According to the working principle of the four-quadrant photodetector and the average amplitude of each first voltage, the position coordinates of the light spots formed by each second light source on the photosensitive surface of the first four-quadrant photodetector are calculated; according to the position coordinates of the light spots formed by each second light source on the photosensitive surface of the first four-quadrant photodetector and the vertical distance between the first converging lens and the first four-quadrant photodetector, the unit vectors of each second light source relative to the coordinate origin O1 are determined, and the coordinate system to which the coordinate origin O1 belongs is a coordinate system O1-X1Y1Z1 established with the center O1 of the first converging lens as the origin and the optical axis direction of the first converging lens as the Z1 axis direction; according to the unit vectors corresponding to each second light source, the vertex angle corresponding to each second light source is determined; according to the vertex angle corresponding to each second light source and the distance between each second light source, the length between the center O1 of the first converging lens and each second light source is determined; according to the length between the center O1 of the first converging lens and each second light source, the coordinates of each second light source in the coordinate system O1-X1Y1Z1 are determined, and according to the coordinates of each second light source, the orientation information of the second communication device is determined, and the corresponding expression is: Where i = 1, 2, 3, 4, represents the unit vector of the i-th second light source relative to the coordinate origin O1, (x 1i ,y 1i ) represents the position coordinates of the light spot formed by the i-th second light source on the photosensitive surface of the first four-quadrant photodetector when the coordinate system is established with the center of the photosensitive surface of the first four-quadrant photodetector as the origin, l1 represents the vertical distance between the first converging lens and the first four-quadrant photodetector; ∠A2O1B2, ∠B2O1C2, ∠C2O1D2, ∠D2O1A2∠A2O1C2 and ∠B2O1D2 represent the vertex angles of the four-sided pyramid formed by the center O1 of the first converging lens and the second light sources, A2B2, B2C2, C2D2, D2A2, A2C2, B2D2 represent the distances between the second light sources respectively, O1A2, O1B2, O1C2, O1D2 represent the lengths between the center O1 of the first converging lens and the second light sources respectively; M 11 、M 12 、M 13 、M 14 Respectively represent the coordinates of each second light source; The second processing unit is specifically used to identify each of the second voltage signals, and use the voltage signal with the highest amplitude to restore the first transmission frame; determine the encoded first data segment and the first navigation mark sequence according to the restored first transmission frame, the first data synchronization sequence and the first navigation synchronization sequence; perform error correction decoding on the encoded first data segment according to the preset error correction coding method to obtain the first data segment; identify the first light source in the first transmitting unit according to the generation method of the first navigation mark sequence, and find the second voltage average amplitude detected by the second receiving unit when each of the first light sources emits light according to each of the second voltage signals; calculate the light spot position coordinates formed by each of the first light sources on the photosensitive surface of the second four-quadrant photodetector according to the working principle of the four-quadrant photodetector and the second voltage average amplitude; calculate the light spot position coordinates formed by each of the first light sources on the photosensitive surface of the second four-quadrant photodetector according to the first light source on the photosensitive surface of the second four-quadrant photodetector The coordinates of the spot position formed on the surface, the vertical distance between the second converging lens and the second four-quadrant photodetector, determine the unit vector of each of the first light sources relative to the coordinate origin O2, the coordinate system to which the coordinate origin O2 belongs is the coordinate system O2-X2Y2Z2 established with the center O2 of the second converging lens as the origin and the optical axis direction of the second converging lens as the Z2 axis direction; according to the unit vector corresponding to each of the first light sources, determine the vertex angle corresponding to each of the first light sources; according to the vertex angle corresponding to each of the first light sources and the distance between each of the first light sources, determine the length between the center O2 of the second converging lens and each of the first light sources; according to the length between the center O2 of the second converging lens and each of the first light sources, determine the coordinates of each of the first light sources in the coordinate system O2-X2Y2Z2, and according to the coordinates of each of the first light sources, determine the orientation information of the first communication device, and the corresponding expression is: Where j = 1, 2, 3, 4, represents the unit vector of the jth first light source relative to the coordinate origin O2, (x 2j ,y 2j ) represents the coordinates of the spot position formed by the jth first light source on the photosensitive surface of the second four-quadrant photodetector when the coordinate system is established with the center of the photosensitive surface of the second four-quadrant photodetector as the origin, l2 represents the vertical distance between the second converging lens and the second four-quadrant photodetector, ∠A1O2B1, ∠B1O2C1, ∠C1O2D1, ∠D1O2A1, ∠A1O2C1 and ∠B1O2D1 represent the vertex angles of the quadrangular pyramid formed by the center O2 of the second converging lens and the first light sources, A1B1, B1C1, C1D1, D1A1, A1C1 and B1D1 represent the distances between the first light sources respectively, O2A1, O2B1, O2C1 and O2D1 represent the lengths between the center O2 of the second converging lens and the first light sources respectively, M 21 、M 22 、M 23 、M 24 Respectively represent the coordinates of each first light source.

6. An integrated method for underwater wireless optical communication and azimuth measurement, characterized in that: Applied to the underwater wireless optical communication and azimuth measurement integrated system as claimed in any one of claims 1 to 5, the method comprising: S1, a first communication device and a second communication device establish a transmission link in a half-duplex communication mode based on preset communication parameters; S2, the first processing unit caches the data information from the first communication data interface to obtain first cache data; the second processing unit caches the data information from the second communication data interface to obtain second cache data; S3, the first processing unit divides the first cache data into a plurality of data segments of preset lengths according to a preset time sequence to obtain a plurality of first data segments; the second processing unit divides the second cache data into a plurality of data segments of preset lengths according to a preset time sequence to obtain a plurality of second data segments; S4, based on the half-duplex communication mode, the first communication device controls one or more first light sources to emit light signals according to the acquisition order of each first data segment, so as to transmit each first data segment from underwater to the second communication device in the form of light signals, so that the second communication device determines the position information of the first communication device according to the received light signals; the second communication device controls one or more second light sources to emit light signals based on the acquisition order of each second data segment, so as to transmit each second data segment from underwater to the first communication device in the form of light signals, so that the first communication device determines the position information of the second communication device according to the received light signals.

7. The method according to claim 6, characterized in that The first communication device controls one or more first light sources to transmit light signals based on the acquisition order of the first data segments, including: The first processing unit adds first information to a first data segment to be transmitted to obtain a first transmission frame, and controls one or more first light sources to transmit light signals based on the first transmission frame, wherein the first information includes a first data synchronization sequence, a first navigation synchronization sequence, and a first navigation mark sequence, wherein the first data synchronization sequence and the first navigation synchronization sequence are preset binary sequences, wherein the first data synchronization sequence is used to obtain time synchronization information and a starting position of the corresponding first data segment during transmission, the first navigation synchronization sequence is used to perform azimuth measurement of the first communication device, and the first navigation mark sequence is used to obtain time synchronization information and a starting position of the first navigation synchronization sequence during transmission; The first communication device determines the position information of the second communication device according to the received optical signal, including: The first receiving unit converts the detected optical signal from the second communication device into four first voltage signals, represented as U 11 , U 12 , U 13 and U 14 and outputting each of the first voltage signals to the first processing unit; The first processing unit obtains the position information of the second communication device and the second data segment transmitted by the second communication device according to each of the first voltage signals, and outputs the second data segment transmitted by the second communication device from the first communication data interface, and outputs the position information of the second communication device from the first position data interface; The second communication device controls one or more second light sources to transmit light signals based on the acquisition order of the second data segments, including: The second processing unit adds second information to the second data segment to be transmitted to obtain a second transmission frame, and controls one or more second light sources to transmit light signals based on the second transmission frame, wherein the second information includes a second data synchronization sequence, a second navigation synchronization sequence, and a second navigation mark sequence, wherein the second data synchronization sequence and the second navigation synchronization sequence are preset binary sequences, wherein the second data synchronization sequence is used to obtain time synchronization information of the corresponding second data segment during transmission, the second navigation synchronization sequence is used to perform azimuth measurement of the second communication device, and the second navigation mark sequence is used to obtain time synchronization information and a starting position of the second navigation synchronization sequence during transmission; The second communication device determines the position information of the first communication device according to the received optical signal, including: The second receiving unit converts the detected optical signal from the first communication device into four second voltage signals, represented by U 21 , U 22 , U 23 and U 24 and outputting each of the second voltage signals to the second processing unit; The second processing unit obtains the orientation information of the first communication device and the first data segment transmitted by the first communication device according to each of the second voltage signals, and outputs the first data segment transmitted by the first communication device from the second communication data interface, and outputs the orientation information of the first communication device from the second orientation data interface.

8. The method according to claim 7, characterized in that The first processing unit adds first information to the first data segment to be transmitted to obtain a first transmission frame, and controls one or more first light sources to transmit light signals based on the first transmission frame, including: The first processing unit performs error correction coding on the first data segment to be transmitted according to a preset error correction coding method to obtain an encoded first data segment; encodes the position of each of the first light sources to obtain four first position marks, represented as A1, B1, C1, and D1, and splices each of the first position marks in a preset order to obtain a first navigation mark sequence; sequentially splices the first data synchronization sequence, the encoded first data segment, the first navigation synchronization sequence, and the first navigation mark sequence together to form the first transmission frame; when the data information in the first transmission frame is the first navigation mark sequence, the corresponding first light source in the first transmitting unit is controlled to generate an optical signal according to the position mark in the first navigation mark sequence; when the data information in the transmission frame is not the first navigation mark sequence, all the first light sources in the first transmitting unit are controlled to generate optical signals; The second processing unit adds second information to the second data segment to be transmitted to obtain a second transmission frame, and controls one or more second light sources to transmit light signals based on the second transmission frame, including: The second processing unit performs error correction coding on the second data segment to be transmitted according to a preset error correction coding method to obtain an encoded second data segment; encodes the position of each of the second light sources to obtain four second position marks, represented by A2, B2, C2, and D2, and splices each of the second position marks in a preset order to obtain a second navigation mark sequence; sequentially splices the second data synchronization sequence, the encoded second data segment, the second navigation synchronization sequence, and the second navigation mark sequence together to form a second transmission frame; when the data information in the second transmission frame is the second navigation mark sequence, the corresponding second light source in the second transmitting unit is controlled to generate an optical signal according to the position mark in the second navigation mark sequence; when the data information in the transmission frame is not the second navigation mark sequence, all the second light sources in the second transmitting unit are controlled to generate optical signals.

9. The method according to claim 8, characterized in that The first receiving unit converts the detected optical signal from the second communication device into four first voltage signals, represented as U 11 , U 12 , U 13 and U 14 and outputting each of the first voltage signals to the first processing unit, including: The first receiving unit converges the optical signal from the second communication device to the photosensitive surface of the first four-quadrant photodetector through the first converging lens to form a first light spot; the first four-quadrant photodetector converts the first light spot into four first current signals, represented by I 11 ,I 12 ,I 13 ,I 14 ; converting each of the first current signals into the first voltage signals through each of the first transimpedance amplifiers, and outputting the signals to the first processing unit; The second receiving unit converts the detected optical signal from the first communication device into four second voltage signals, represented by U 21 , U 22 , U 23 and U 24 and outputting each of the second voltage signals to the second processing unit, including: The second receiving unit converges the optical signal from the first communication device to the photosensitive surface of the second four-quadrant photodetector through the second converging lens to form a second light spot; the second light spot is converted into four second current signals through the second four-quadrant photodetector, represented by I 21 ,I 22 ,I 23 ,I 24 ; Each of the second voltage signals is converted into the second voltage signal through each of the second transimpedance amplifiers, and output to the second processing unit.

10. The method according to claim 9, characterized in that The first processing unit obtains the position information of the second communication device and the second data segment transmitted by the second communication device according to each of the first voltage signals, including: The first processing unit identifies each of the first voltage signals, and uses the voltage signal with the highest amplitude to restore the second transmission frame; determines the encoded second data segment and the second navigation mark sequence according to the restored second transmission frame, the second data synchronization sequence and the second navigation synchronization sequence; performs error correction decoding on the encoded second data segment according to the preset error correction coding method to obtain the second data segment; identifies the second light source in the second transmitting unit according to the generation method of the second navigation mark sequence, and searches for the first voltage average amplitude detected by the first receiving unit when each of the second light sources emits light according to each of the first voltage signals; calculates the position coordinates of the light spot formed by each of the second light sources on the surface of the first four-quadrant photodetector according to the working principle of the four-quadrant photodetector and the first voltage average amplitude, and calculates the position coordinates of the light spot formed by each of the second light sources on the photosensitive surface of the first four-quadrant photodetector according to the second light source The position coordinates of the light spot and the vertical distance between the first converging lens and the first four-quadrant photodetector are used to determine the unit vector of each of the second light sources relative to the coordinate origin O1, and the coordinate system to which the coordinate origin O1 belongs is a coordinate system O1-X1Y1Z1 established with the center O1 of the first converging lens as the origin and the optical axis direction of the first converging lens as the Z1 axis direction; according to the unit vector corresponding to each of the second light sources, the vertex angle corresponding to each of the second light sources is determined; according to the vertex angle corresponding to each of the second light sources and the distance between each of the second light sources, the length between the center O1 of the first converging lens and each of the second light sources is determined; according to the length between the center O1 of the first four-quadrant photodetector and each of the second light sources, the coordinates of each of the second light sources in the coordinate system O1-X1Y1Z1 are determined, and according to the coordinates of each of the second light sources, the orientation information of the second communication device is determined, and the relevant expression is: Where i = 1, 2, 3, 4, represents the unit vector of the i-th second light source relative to the coordinate origin O1, (x 1i ,y 1i ) represents the position coordinates of the light spot formed by the i-th second light source on the photosensitive surface of the first four-quadrant photodetector when the coordinate system is established with the center of the photosensitive surface of the first four-quadrant photodetector as the origin, l1 represents the vertical distance between the first converging lens and the first four-quadrant photodetector, ∠A2O1B2, ∠B2O1C2, ∠C2O1D2, ∠D2O1A2∠A2O1C2 and ∠B2O1D2 represent the vertex angles of the quadrangular pyramid formed by the center O1 of the first converging lens and each second light source, A2B2, B2C2, C2D2, D2A2, A2C2, B2D2 represent the distances between each second light source, O1A2, O1B2, O1C2, O1D2 represent the lengths between the center O1 of the first converging lens and each second light source, respectively; M 11 、M 12 、M 13 、M 14 Respectively represent the coordinates of each second light source, and determine the orientation information of the second communication device according to the coordinates of each second light source; The second processing unit obtains the position information of the first communication device and the first data segment transmitted by the first communication device according to each of the second voltage signals, including: The second processing unit identifies each of the second voltage signals, and uses the voltage signal with the highest amplitude to restore the first transmission frame; determines the encoded first data segment and the first navigation mark sequence according to the restored first transmission frame, the first data synchronization sequence and the first navigation synchronization sequence; performs error correction decoding on the encoded first data segment according to the preset error correction coding method to obtain the first data segment; identifies the first light source in the first transmitting unit according to the generation method of the first navigation mark sequence, and searches for the second voltage average amplitude detected by the second receiving unit when each of the first light sources emits light according to each of the second voltage signals; calculates the light spot position coordinates formed by each of the first light sources on the photosensitive surface of the second four-quadrant photodetector according to the working principle of the four-quadrant photodetector and the second voltage average amplitude; calculates the light spot position coordinates formed by each of the first light sources on the photosensitive surface of the second four-quadrant photodetector according to the first light source The unit vector of each of the first light sources relative to the coordinate origin O2 is determined based on the coordinates of the light spot position and the vertical distance between the second converging lens and the second four-quadrant photodetector. The coordinate system to which the coordinate origin O2 belongs is a coordinate system O2-X2Y2Z2 established with the center O2 of the second converging lens as the origin and the optical axis direction of the second converging lens as the Z2 axis direction; the vertex angle corresponding to each of the first light sources is determined based on the unit vector corresponding to each of the first light sources; the length between the center O2 of the second converging lens and each of the first light sources is determined based on the vertex angle corresponding to each of the first light sources and the distance between each of the first light sources; the coordinates of each of the first light sources in the coordinate system O2-X2Y2Z2 are determined based on the length between the center O2 of the second converging lens and each of the first light sources; the orientation information of the first communication device is determined based on the coordinates of each of the first light sources, and the corresponding expression is: Where j = 1, 2, 3, 4, represents the unit vector of the jth first light source relative to the coordinate origin O2, (x 2j ,y 2j ) represents the coordinates of the spot position formed by the jth first light source on the photosensitive surface of the second four-quadrant photodetector when the coordinate system is established with the center of the photosensitive surface of the second four-quadrant photodetector as the origin, l2 represents the vertical distance between the second converging lens and the second four-quadrant photodetector, ∠A1O2B1, ∠B1O2C1, ∠C1O2D1, ∠D1O2A1, ∠A1O2C1 and ∠B1O2D1 represent the vertex angles of the quadrangular pyramid formed by the center O2 of the second converging lens and the first light sources, A1B1, B1C1, C1D1, D1A1, A1C1 and B1D1 represent the distances between the first light sources, O2A1, O2B1, O2C1 and O2D1 represent the lengths between the center O2 of the second converging lens and the first light sources, M 21 、M 22 、M 23 、M 24 Respectively represent the coordinates of each first light source.

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