Navigation method based on underwater polarized light detection

Abstract

The invention discloses a navigation method based on underwater polarized light detection, which belongs to the technical field of navigation, is used for underwater navigation, and comprises the following steps: collecting polarization images by a polarization camera, calculating a polarization angle by combining with a single scattering model, and outputting a pitch angle and an azimuth angle of the polarization camera by a three-dimensional electronic compass; the polarization angle and the position of the polarization camera are input into a sun position resolving module together for processing, a sun azimuth angle and a sun zenith angle are obtained, and then latitude and longitude are output through a latitude and longitude resolving module. Underwater navigation is realized by combining polarized light, and longitude and latitude errors of navigation are respectively 0.17609 degrees and 0.24156 degrees by combining the result of the embodiment, so that a novel underwater navigation method is successfully realized.

Description

Technical Field

[0001] The invention discloses a navigation method based on underwater polarized light detection, belonging to the technical field of navigation. Background Art

[0002] There are two limitations in the underwater navigation of the prior art. The first is that satellite navigation cannot be used underwater, and the second is that the inertial navigation error accumulates over time and must be corrected by certain means. To solve the above problems, it is found that in terrestrial animals, especially in arthropods such as ants, bees, crickets, dung beetles and spiders, it is well documented to use photoreceptor arrays that are particularly sensitive to the polarization pattern of light for navigation. For example, bees rely on predictable polarization patterns relative to the position of the sun to travel between hives. This research direction has recently been extended to vertebrates. Migratory birds at longer distances use the polarization pattern of the sunrise and sunset sky to calibrate their compasses. Although the exploration and development of underwater environments is relatively small, studies have shown that marine animals can use the polarization pattern of the sky observed from underwater as a navigation compass. For example, mantis shrimps have sensitive polarization vision and can perceive polarized light and navigate. In order to realize underwater polarized light navigation, it is found that the polarized light navigation method based on atmospheric Rayleigh scattering has the advantages of strong anti-interference ability, high reliability, wide application range and no accumulation of positioning errors over time. It is one of the frontier topics in navigation science research.

[0003] For underwater polarized light navigation, a Chinese patent with announcement number CN114894197B discloses an underwater polarization autonomous heading calculation method based on real-time tracking of the zenith point. The underwater polarization azimuth image and the underwater polarization degree image are solved from the underwater polarized light intensity image. The pixel coordinates of the zenith point mapping point in the underwater polarization azimuth image are dynamically tracked using the pitch angle, roll angle and lens model, and then the ambiguous solar azimuth is solved, and the ambiguity is eliminated based on the underwater polarization degree image. The vehicle heading is obtained by combining the solar azimuth in the geographic coordinate system calculated by the solar calendar. The Chinese patent application with publication number CN112379399A discloses a polarized light navigation and positioning method based on a multi-configuration fisheye camera, which measures the angle of the geographic south direction by using an electronic compass configured on the fisheye camera, and measures the polarization azimuth at three different times by rotating the polarizer using a polarized light measuring device, and the fisheye camera is equipped with an astronomical query module to check the solar latitude at three different times, and the solar azimuth of the fisheye camera observation point at three different times is obtained by calculating the three solar latitudes. The above-mentioned prior art realizes underwater polarized light navigation, but does not analyze the incident light one by one throughout the entire process. The present invention analyzes the incident light process one by one to realize a new underwater polarized light navigation. Summary of the invention

[0004] The purpose of the present invention is to provide a navigation method based on underwater polarized light detection to solve the problem in the prior art that underwater polarized light navigation does not analyze the entire incident process of the light, thereby affecting the navigation accuracy.

[0005] A navigation method based on underwater polarized light detection, comprising: a polarization camera collecting polarized images, and calculating the polarization angle in combination with a single scattering model, a three-dimensional electronic compass outputting the pitch angle and azimuth angle of the polarization camera, inputting the polarization angle and the position of the polarization camera together into a solar position solution module for processing, obtaining the solar azimuth angle and the solar zenith angle, and then outputting the longitude and latitude through a longitude and latitude solution module; calculating the polarization angle comprises calculating the Stokes vector of refracted light, calculating the Stokes vector of scattered light, and obtaining the polarization angle; The Stokes vector of the scattered light is : ; ; ; ; In the formula, is the Miller matrix of the light transforming from the scattering plane to the polarization camera, is the Rayleigh scattering matrix, is the Miller matrix corresponding to the coordinate transformation of light in the process of refraction to scattering, is the intermediate matrix, is the Stokes vector of the incident light, is the intermediate parameter, is the refractive index of air, is the refractive index of water, is the water surface normal vector, is the wave vector of the incident light, is the wave vector of the refracted light.

[0006] In the single scattering model, sunlight is divided into incident light, refracted light and scattered light in sequence. The incident light is the sunlight before entering the water, the refracted light is the sunlight after entering the water, and the scattered light is the sunlight that is scattered by the refracted light and finally enters the polarization camera.

[0007] for: .

[0008] Calculating the Stokes vector of the refracted light includes: The Stokes vector of the refracted light is : ; ; ; In the formula, represents the approximate solar azimuth, Indicates the approximate solar zenith angle.

[0009] Calculating the Stokes vector of scattered light involves, for: ; The direction of the zero polarization angle in the coordinate system of the refracted light is , the direction of the zero polarization angle in the coordinate system where the scattered light is located is , for and The angle between for: ; ; In the formula, is the adjustment factor related to the scattering angle, is the scattering angle, is the refractive index of the medium, is the scattering cross section, which indicates the effect of the properties of the scattering medium on the scattering of polarized light. is a function of the scattering angle.

[0010] The polarization angle is obtained by Rewritten in component form: ; In the formula, , , , yes The four components of Calculate polarization angle : .

[0011] The polarization angle and the position of the polarization camera are input into the sun position solution module for processing, including: ; ; In the formula, are the solar position parameters, including the solar azimuth angle and the solar zenith angle, is the position of the polarization camera, is the approximate solar position parameter, including the approximate solar azimuth angle and the approximate solar zenith angle. Indicates the minimum value, Represents the vector composed of polarization angles at different positions detected by the polarization camera, Indicates the angle difference operation. is the polarization angle, Express Perform L1 norm operation, is the periodic constant, is a modulo operation; The wave vectors at different positions include the incident light wave vector, the refracted light wave vector and the scattered light wave vector. The scattered light wave vector is : ; In the formula, is the azimuth of the polarization camera, is the pitch angle of the polarization camera.

[0012] The longitude and latitude output by the longitude and latitude calculation module include: ; In the formula, is the precise latitude and longitude of the observation location, is the objective function to solve the angular distance between two positions, is the estimated latitude and longitude of the observation location, It's time. is based on and The sun position parameters calculated by the algorithm.

[0013] After the polarization camera collects an image, it obtains polarization images in four directions. The corresponding interference-free area is selected on each polarization image. The corresponding light intensity values ​​of the polarization images in the four directions are .

[0014] Degree of Polarization for: ; When performing underwater polarization detection-based navigation, select the point with the maximum polarization degree for measurement.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the present invention realizes underwater navigation by combining polarized light. Combined with the results of the embodiment, the longitude and latitude errors of navigation are 0.17609° and 0.24156° respectively, which overcomes the problem of low precision caused by the inability to use satellites for underwater navigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a technical flow chart of the present invention; Figure 2 is a schematic diagram of the position of the incident light; Figure 3Schematic diagram of single scattering model; Figure 4 It is a schematic diagram of coordinate transformation; Figure 5 Schematic diagram of polarization camera position parameters; Figure 6 This is the AOP simulation diagram with the solar zenith angle set to 10 degrees; Figure 7 This is the AOP simulation diagram with the solar zenith angle set to 45 degrees; Figure 8 This is the AOP simulation diagram with the solar zenith angle set to 80 degrees; Fig. 9 This is a DOP simulation diagram with the solar zenith angle set to 10 degrees; Fig.10 This is a DOP simulation diagram with the solar zenith angle set to 45 degrees; Fig.11 This is a DOP simulation diagram with the solar zenith angle set to 80 degrees; Fig.12 The predicted and actual sun positions for 50 dB. Fig.13 The sun's position predicted by 10dB and its actual position. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] A navigation method based on underwater polarized light detection includes collecting polarized images with a polarized camera and calculating the polarization angle in combination with a single scattering model; a three-dimensional electronic compass outputs the pitch angle and azimuth angle of the polarized camera; the polarization angle and the position of the polarized camera are input into a solar position solution module for processing to obtain the solar azimuth angle and the solar zenith angle; and the longitude and latitude are output through a longitude and latitude solution module.

[0019] In the single scattering model, sunlight is divided into incident light, refracted light and scattered light in sequence. The incident light is the sunlight before entering the water, the refracted light is the sunlight after entering the water, and the scattered light is the sunlight that is scattered by the refracted light and finally enters the polarization camera.

[0020] Calculating the polarization angle includes calculating the Stokes vector of the refracted light, calculating the Stokes vector of the scattered light, and obtaining the polarization angle.

[0021] Calculating the Stokes vector of the refracted light includes: The Stokes vector of the incident light is : ; The Stokes vector of the refracted light is : ; ; ; ; ; ; In the formula, is the intermediate parameter, is the intermediate matrix, is the refractive index of air, is the refractive index of water, is the water surface normal vector, is the wave vector of the incident light, is the wave vector of the refracted light, represents the approximate solar azimuth, Indicates the approximate solar zenith angle.

[0022] The calculation of the Stokes vector of scattered light includes the following steps: the Miller matrix corresponding to the coordinate transformation of the light during the process of refraction to scattering is: : ; The direction of the zero polarization angle in the coordinate system of the refracted light is , the direction of the zero polarization angle in the coordinate system where the scattered light is located is , for and The angle between The Rayleigh scattering matrix is : ; ; In the formula, is the adjustment factor related to the scattering angle, is the scattering angle, is the refractive index of the medium, is the scattering cross section, which indicates the effect of the properties of the scattering medium on the scattering of polarized light. is a function of the scattering angle variation; The Stokes vector of the scattered light is : ; In the formula, is the Miller matrix that transforms light from the scattering plane to the polarization camera.

[0023] The polarization angle is obtained by Rewritten in component form: ; In the formula, , , , yes The four components of Calculate polarization angle : .

[0024] The polarization angle and the position of the polarization camera are input into the sun position solution module for processing, including: ; ; In the formula, are the solar position parameters, including the solar azimuth angle and the solar zenith angle, is the position of the polarization camera, is the approximate solar position parameter, including the approximate solar azimuth angle and the approximate solar zenith angle. Indicates the minimum value, Represents the vector composed of polarization angles at different positions detected by the polarization camera, Indicates the angle difference operation. is the polarization angle, Express Perform L1 norm operation, is the periodic constant, is a modulo operation; The wave vectors at different positions include the incident light wave vector, the refracted light wave vector and the scattered light wave vector. The scattered light wave vector is : ; In the formula, is the azimuth of the polarization camera, is the pitch angle of the polarization camera.

[0025] The longitude and latitude output by the longitude and latitude calculation module include: ; In the formula, is the precise latitude and longitude of the observation location, is the objective function to solve the angular distance between two positions, is the estimated latitude and longitude of the observation location, It's time. is based on and The sun position parameters calculated by the algorithm.

[0026] After the polarization camera collects an image, it obtains polarization images in four directions. The corresponding interference-free area is selected on each polarization image. The corresponding light intensity values ​​of the polarization images in the four directions are .

[0027] Degree of Polarization for: ; When performing underwater polarization detection-based navigation, select the point with the maximum polarization degree for measurement.

[0028] The technical process of the present invention is as follows Figure 1 As shown, a polarization camera collects polarization images and calculates the polarization angle in combination with a single scattering model. A three-dimensional electronic compass outputs the pitch angle and azimuth angle of the polarization camera. The polarization angle and the position of the polarization camera are input into a solar position solution module for processing to obtain the solar azimuth angle and the solar zenith angle. A global magnetic declination database is introduced to correct the solar azimuth angle, and then the longitude and latitude are output through a longitude and latitude solution module in combination with time and other information.

[0029] The position of the incident light is Figure 2 As shown in the figure, the celestial coordinate system is established. The position of the sun is described by the solar zenith angle and the solar azimuth angle. The zenith angle is measured downward from the zenith direction, and the azimuth angle is measured eastward from the due north direction. At the same time, the due east direction is the x-axis direction, the due north direction is the y-axis direction, and the zenith direction is the z-axis direction. The single scattering model is as follows Figure 3 As shown, the light starts from the sun and passes through the wave vector of the incident light. , the wave vector of refracted light , the wave vector of scattered light , the coordinate vector includes the direction of the zero polarization angle in the coordinate system where the refracted light is located. , the direction of the zero polarization angle in the coordinate system where the incident light is located is , the direction of the zero polarization angle in the coordinate system where the scattered light is located is , is the direction of zero polarization angle of scattered light; .

[0030] Coordinate transformation is shown as follows Figure 4 As shown, , is the coordinate system corresponding to the refracted light, , is the coordinate system corresponding to the scattering plane, is the direction corresponding to the 0 polarization angle after coordinate transformation, and The angle is .

[0031] Polarization camera position parameters are shown below: Figure 5 As shown, , is the coordinate system of the polarization camera. The AOP simulation diagrams with solar zenith angles of 10 degrees, 45 degrees, and 80 degrees are shown in Figure 1. Figure 6 , Figure 7 , Figure 8 As shown in the figure, in the polarization angle simulation, the solar azimuth is 0 degrees, the azimuth angle of the polarization camera ranges from -180 degrees to 180 degrees, and the elevation angle ranges from -90 degrees to 90 degrees. Different colors in the figure correspond to different polarization angles, such as dark blue corresponds to the range of about 30 degrees to 70 degrees, and pink corresponds to the range of 120 degrees to 150 degrees. The short dashed line in the figure indicates the direction of polarization at the corresponding position, so when the zenith angle is 10 degrees, it is basically polarized in the horizontal direction, and the entire area does not change much. As the zenith angle increases, the vertical polarization component gradually increases. When the zenith angle is 80 degrees, the change of the polarization angle in the area is relatively obvious.

[0032] The DOP simulations for solar zenith angles of 10 degrees, 45 degrees, and 80 degrees are as follows: Fig. 9 , Fig.10 , Fig.11 As shown in the figure, different colors represent different degrees of polarization. A degree of polarization of 0 represents unpolarized light, and a degree of polarization of 1 represents fully polarized light. Generally, polarized light is between 0 and 1. It can be seen from the figure that the degree of polarization is distributed in a band shape, and the change is quite obvious. In the underwater polarized light navigation model, the position with a larger degree of polarization can be selected for measurement according to the DOP simulation diagram to reduce the error. The predicted sun position of 50dB is different from the actual position. Fig.12 As shown in the figure, the sun position predicted by 10dB is different from the actual position. Fig.13 shown.

[0033] The single scattering model includes the solar zenith angle, azimuth angle, elevation angle of the polarization camera, azimuth angle, refractive index and parameters related to scattering. Among them, the refractive index of seawater is generally related to temperature, seawater salinity and wavelength of incident light. In order to facilitate simulation, a constant of 1.33 is used. The parameters related to scattering are also related to the specific ocean environment and scattering particles, so constants are also used here. Therefore, in the simulation, the only parameters that are variables are the solar zenith angle, azimuth angle, elevation angle and azimuth angle of the polarization camera. The simulation results are the degree of polarization and polarization angle calculated by the Stokes vector. These two quantities are independent of light intensity and are less affected by interference, so they can be used to better describe the underwater polarization environment. In the polarization angle simulation, the solar azimuth angle is 0 degrees, the solar zenith angle is set to 10 degrees, 45 degrees and 80 degrees respectively, the azimuth angle of the polarization camera ranges from -180 degrees to 180 degrees, and the elevation angle ranges from -90 degrees to 90 degrees. The simulation parameters of the degree of polarization are the same as those set for the polarization angle. The underwater polarized light navigation model is mainly composed of three parts: measurement and image acquisition module, sun position solution module, and longitude and latitude solution module. The measurement and image acquisition module includes a polarization camera, a three-dimensional electronic compass, and an instrument for measuring altitude. The polarization camera is responsible for collecting polarization images and calculating the polarization angle based on the obtained Stokes vector. The three-dimensional electronic compass is bound to the polarization camera and follows the polarization camera to make horizontal and elevation rotations, while outputting the azimuth and elevation angles of the camera. The core of the sun position solution module is to use the single scattering model and optimization algorithm to obtain the sun position based on the polarization angle information and the camera position. The azimuth needs to be corrected according to the global magnetic declination database before being input into the longitude and latitude solution module. Finally, after the necessary parameters such as date, time, and measurement altitude are known, the longitude and latitude solution module is used to finally obtain the longitude and latitude information to achieve navigation positioning.

[0034] During the simulation, a set of AOP data was generated. The time was selected at 10 am on April 20, 2020, the location was selected as longitude and latitude 120.17672 degrees east longitude, 35.94334 degrees north latitude, and the altitude was 0m. The parameters were input into the single scattering model to obtain the AOP information, and then different degrees of Gaussian noise were added to solve the solar position. The average value data was brought into the solar position solution module to obtain the longitude and latitude data of 120.0006° and 35.70178°, and the corresponding errors were 0.17609° and 0.24156°, respectively.

[0035] Compared with ordinary imaging sensors, the advantage of polarization cameras is that they can collect light intensities in different polarization directions. For example, Sony's polarization imaging sensor places a polarizer above the photodiode of the CMOS sensor. Four polarizers with different angles (90 degrees, 45 degrees, 135 degrees, and 0 degrees) are placed on a single pixel. Each pixel can only collect the light intensity passing through the corresponding polarizer direction, and each group of four pixels serves as a calculation unit. Using this design, the polarization information of the collected image can be calculated.

[0036] The three-dimensional electronic compass is an instrument that uses the geomagnetic field to calibrate the north and south. It is generally composed of a three-dimensional magnetoresistive sensor, two inclination sensors and an MCU. The three-dimensional electronic compass is bound to the polarization camera and rotates with the polarization camera. It can measure and output the pitch angle and azimuth angle of the polarization camera in real time. The built-in MCU can process the signal and output the data while performing soft iron and hard iron compensation. The three-dimensional electronic compass needs to filter the signal when in use to eliminate the influence of noise.

[0037] The basic principle of the solar position calculation module is to use the L1 norm as the objective function to search for the optimal solution within a specified range to obtain the solar position. The Scipy module of Python is used to solve the specific calculation. The L-BFGS-B algorithm is used to solve the optimization problem. The L-BFGS-B algorithm is the most commonly used method for solving unconstrained nonlinear programming, with the characteristics of fast convergence speed and low memory overhead. During the simulation process, a set of solar position parameters is assumed, and multiple sets of polarization angles are calculated through the single scattering model under this parameter. In order to meet the noise disturbance in the actual situation, Gaussian noise with different signal-to-noise ratios is added to the simulated data, and then the data is input to the solar position calculation module. Gaussian noise is generated by the Numpy module of Python. The signal-to-noise ratio is used to compare the intensity of the required signal with the intensity of the background noise. It is defined as the ratio of signal power to noise power, expressed in decibels (dB). A value higher than 0 decibels indicates that the signal is greater than the noise.

[0038] In actual measurement, the azimuth measured by the electronic compass is based on the geomagnetic North Pole, while the sun position calculated by longitude and latitude is based on the geographic North Pole. The two do not coincide, and the magnetic north direction is generally slightly east of the true north direction. The angle between the magnetic north direction and the true north direction is the magnetic declination. In the process of longitude and latitude solution, the azimuth needs to be corrected for magnetic declination first. In the optimization calculation, the large number of position selections has a greater impact on the calculation results. This is obvious. When the number of position selections increases, it becomes less easy to meet the polarization state in each direction, avoid falling into the local optimal solution, and it is easier to find the global optimal phase-locked amplifier, which is usually used to detect weak signals. Phase-sensitive detection technology is used to extract the amplitude and phase of the signal at the reference frequency, and suppress the noise on the non-reference frequency, so as to achieve the effect of suppressing noise in the frequency domain. The Signaloc 2100 phase-locked amplifier is used in the present invention. The simulation results are the degree of polarization and polarization angle calculated by the Stokes vector. These two are quantities that are independent of light intensity, are less disturbed, and can be used to describe the underwater polarization environment better.

[0039] In the present invention, the degree of polarization (DOP) as a key quantity of polarized light can reflect the polarization state of underwater light, and thus provide quantitative information for the scattering characteristics of underwater materials. Its application in the present invention is of great significance, mainly reflected in the following aspects: Evaluating the strength of the interaction between light and underwater materials: The degree of polarization can characterize the degree of influence of suspended particles, dissolved substances, etc. in the water body on the polarization of light. By monitoring the changes in the degree of polarization, the optical properties of the underwater environment can be inferred to help analyze the interaction between light and underwater materials. Identification of light sources and scattering objects: The degree of polarization of scattered light behaves differently under different underwater objects or environmental conditions. By calculating the degree of polarization, the system can identify and distinguish underwater objects, thereby improving the accuracy and stability of underwater navigation. Optimizing underwater navigation accuracy: As an optical signal processing tool, the degree of polarization can help optimize the positioning accuracy of the navigation system. By combining the degree of polarization information with other optical measurements (such as scattering angle, light intensity, etc.), the system can select the best optical detection mode to improve the effect of the underwater navigation system.

[0040] In the underwater polarization detection navigation method, it is crucial to calculate the wave vectors of incident light, refracted light, and scattered light. The role of these three wave vectors is to describe the propagation path and direction of the interaction between light and the water surface and underwater materials, and then provide the underwater navigation system with information on the propagation characteristics of light. Specifically, their roles are as follows.

[0041] The role of the incident light wave vector is to describe the direction of incidence of light from the sun. The function is to determine the incident direction of light through the solar azimuth and zenith angle, which is crucial for subsequent refraction and scattering calculations. It provides the starting direction of the light for the entire optical calculation, that is, the direction of light from the sun to the water surface. The role of the refracted light wave vector is to describe the propagation direction of light from the air into the water after passing through the water surface. The function is that the calculation of the refracted light wave vector is based on Snell's law, taking into account the water surface normal vector and the refractive index of air and water. This allows the calculation of the propagation path of light in water and describes the refraction process between light and the water surface, which helps to accurately simulate the behavior of light in water. The role of the scattered light wave vector is to describe the propagation direction of light scattered after interacting with water substances (such as suspended particles) in water. The function is to determine the direction of scattered light through the azimuth and pitch angles of the polarization camera. This is a description of the interaction between light and water substances, which helps the system capture the path of scattered light and analyze the distribution of objects and other optical properties in underwater environments.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features may be replaced by equivalents, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A navigation method based on underwater polarized light detection, characterized in that: The method includes collecting polarization images with a polarization camera and calculating the polarization angle in combination with a single scattering model. The three-dimensional electronic compass outputs the pitch angle and azimuth angle of the polarization camera. The polarization angle and the position of the polarization camera are input into a solar position calculation module for processing to obtain the solar azimuth angle and solar zenith angle. The longitude and latitude calculation module then outputs the longitude and latitude. Calculating the polarization angle includes calculating the Stokes vector of the refracted light, calculating the Stokes vector of the scattered light, and obtaining the polarization angle. The Stokes vector of the scattered light is : ； ； ； ； In the formula, is the Miller matrix of the light transforming from the scattering plane to the polarization camera, is the Rayleigh scattering matrix, is the Miller matrix corresponding to the coordinate transformation of light in the process of refraction to scattering, is the intermediate matrix, is the Stokes vector of the incident light, is the intermediate parameter, is the refractive index of air, is the refractive index of water, is the water surface normal vector, is the wave vector of the incident light, is the wave vector of the refracted light.

2. A navigation method based on underwater polarized light detection according to claim 1, characterized in that: In the single scattering model, sunlight is divided into incident light, refracted light and scattered light in sequence. The incident light is the sunlight before entering the water, the refracted light is the sunlight after entering the water, and the scattered light is the sunlight that is scattered by the refracted light and finally enters the polarization camera.

3. A navigation method based on underwater polarized light detection according to claim 2, characterized in that: for: 。 4. The navigation method based on underwater polarized light detection according to claim 3, characterized in that: Calculating the Stokes vector of the refracted light includes: The Stokes vector of the refracted light is : ； ； ； In the formula, represents the approximate solar azimuth, Indicates the approximate solar zenith angle.

5. The navigation method based on underwater polarized light detection according to claim 4, characterized in that: Calculating the Stokes vector of scattered light involves, for: ； The direction of the zero polarization angle in the coordinate system of the refracted light is , the direction of the zero polarization angle in the coordinate system where the scattered light is located is , for and The angle between for: ； ； In the formula, is the adjustment factor related to the scattering angle, is the scattering angle, is the refractive index of the medium, is the scattering cross section, which indicates the effect of the properties of the scattering medium on the scattering of polarized light. is a function of the scattering angle.

6. A navigation method based on underwater polarized light detection according to claim 5, characterized in that: The polarization angle is obtained by Rewritten in component form: ； In the formula, , , , yes The four components of Calculate polarization angle : 。 7. The navigation method based on underwater polarized light detection according to claim 6, characterized in that: The polarization angle and the position of the polarization camera are input into the sun position solution module for processing, including: ； ； In the formula, are the solar position parameters, including the solar azimuth angle and the solar zenith angle, is the position of the polarization camera, is the approximate solar position parameter, including the approximate solar azimuth angle and the approximate solar zenith angle. Indicates the minimum value, Represents the vector composed of polarization angles at different positions detected by the polarization camera, Indicates the angle difference operation. is the polarization angle, Express Perform L1 norm operation, is the periodic constant, is a modulo operation; The wave vectors at different positions include the incident light wave vector, the refracted light wave vector and the scattered light wave vector. The scattered light wave vector is : ； In the formula, is the azimuth of the polarization camera, is the pitch angle of the polarization camera.

8. The navigation method based on underwater polarized light detection according to claim 7, characterized in that: The longitude and latitude output by the longitude and latitude calculation module include: ； In the formula, is the precise latitude and longitude of the observation location, is the objective function to solve the angular distance between two positions, is the estimated latitude and longitude of the observation location, It's time. is based on and The sun position parameters calculated by the algorithm.

9. The navigation method based on underwater polarized light detection according to claim 1, characterized in that: After the polarization camera collects an image, it obtains polarization images in four directions. The corresponding interference-free area is selected on each polarization image. The corresponding light intensity values ​​of the polarization images in the four directions are .

10. The navigation method based on underwater polarized light detection according to claim 6, characterized in that: Degree of Polarization for: ； When performing underwater polarization detection-based navigation, select the point with the maximum polarization degree for measurement.

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