An underwater point source polarized light detection device and a method for measuring heading angle thereof

Abstract

The present application provides an underwater point source polarization light detection device and a method for measuring a heading angle thereof, which are applied to the field of polarization navigation technology, wherein the polarization light detection device comprises a base, a rotating detection platform arranged on the base, and three groups of polarization light detection modules arranged on the top of the rotating detection platform, wherein the three groups of polarization light detection modules adopt the same structure and each group of detection modules is composed of a pair of polarization analysis channels whose transmission directions are perpendicular to each other, the other two groups of detection modules are positioned so that the polarization light detection directions of the two are left-right symmetrical about the zenith polarization light detection direction in the same plane and the angles between the two and the zenith polarization light detection direction do not exceed 5°, the rotating detection platform is configured to be able to rotate 360° around the axis where the zenith polarization light detection direction is located, and the heading angle measurement method using the detection device has the advantages of good adaptability to underwater environments and a small number and type of polarization analysis channels used.

Description

Technical Field

[0001] The present application relates to the field of polarized light navigation technology, and in particular to an underwater point source polarized light detection device and a method for measuring a heading angle thereof. Background Art

[0002] As a natural resource, sunlight contains a wealth of physical information that can be used to guide practical activities, such as atmospheric information used to analyze atmospheric composition, temperature and pressure distribution, or polarized light information that can be used for navigation and positioning. It is known that some aerosol particles in the atmosphere will scatter sunlight, and the vibration direction of some light waves will be limited to a specific direction, thereby forming the polarized light. In order to effectively capture useful polarized light information in the atmosphere, there are many devices for detecting polarized light in the prior art. For example, Chinese patent No. CN101694456A discloses a full-sky atmospheric polarization mode detection sensor and a related detection signal processing method, and Chinese patent No. CN101441171A discloses a four-channel atmospheric polarization information detection sensor signal processing and compensation method. Both of them expect to achieve related technical purposes such as navigation and positioning of bionic robots or underwater vehicles by detecting and analyzing atmospheric polarized light information in the target area.

[0003] In underwater environments, GPS signals are denied and inertial navigation has cumulative errors. In order to improve the heading angle accuracy of underwater robots in long-range navigation, the bionic polarized light navigation method has become a research hotspot. The so-called bionic polarized light navigation method is a method of navigating by imitating the regular distribution of atmospheric polarized light by organisms such as sand ants and bees. It has been learned that the distribution of atmospheric polarized light has at least the following rules: under the Rayleigh scattering model, the polarized light direction at the solar meridian and the anti-solar meridian is perpendicular to the solar meridian and the anti-solar meridian, the polarization direction of any observation point in the atmosphere is perpendicular to the line between the observation point and the sun, and the atmospheric polarized light has the characteristics of being symmetrical with the solar meridian and the anti-solar meridian, and the polarization degree on the anti-solar meridian side is greater than the polarization degree on the solar meridian side.

[0004] The point source polarized light navigation method based on the local sky polarized light area is one of the more common bionic polarized light navigation methods. This method usually uses the following steps to measure the heading angle: first, the polarized light image in the zenith direction is collected by a polarization detection sensor with four channels (i.e., four polarization analysis channels); secondly, the collected polarized light image is processed and the polarization degree information and the polarization angle information relative to the reference direction at the observation point are solved by methods such as the light intensity change curve analysis method or the Stokes vector method; then, the angle between the forward direction of the carrier and the solar meridian, i.e., the heading angle of the carrier, is calculated according to the obtained polarization angle information. In this process, since the polarization state has a 180-degree periodicity with the change of the polarization angle, there is a problem that two polarization angles can lead to the same polarization state, i.e., the 180-degree ambiguity problem. To solve this problem, the heading angle measurement method based on the PFAC model or the heading angle measurement method based on the K-means clustering algorithm in the prior art requires the detection of atmospheric polarization information of different sky areas deviating from the zenith direction, and the specific position of the sun is estimated using this atmospheric polarization information.

[0005] The existing point source polarized light navigation method has at least the following potential problems when applied: 1. Affected by the refraction that occurs when light enters different media, there is a certain difference between the atmospheric polarization mode detected by the atmospheric detection point in the direction deviating from the zenith and the polarization mode detected by the corresponding underwater detection point. This makes the above-mentioned heading angle measurement method that requires detection of atmospheric polarization information deviating from the zenith direction not applicable to underwater environments, thereby solving the above-mentioned 180-degree ambiguity problem. Second, the polarization light detection sensor based on the PFAC model needs to be equipped with two types of polarization detection channels: polarization information receiving channel and non-polarization information receiving channel. At the same time, a multi-channel time-division multiplexing method is required for signal processing, which not only increases the structural complexity of the sensor itself, but also makes the processing of polarization information complicated. The heading angle measurement method based on the K-means clustering algorithm generally requires the use of multiple four-channel polarization light detection sensors to detect the atmospheric polarization information in each target direction in the sky during the same period of time as the basis for clustering analysis. Since the number of channels that need to be controlled in the detection sensor is large, more photoelectric detection devices and circuit control devices are required accordingly, which makes the structural complexity of the entire detection system high. Since the consistency and accuracy of the data transmitted by each channel must be ensured, the processing of polarization information becomes complicated, which increases the measurement cost.

[0006] In view of this, there are at least the following problems that need to be solved urgently in the current prior art, namely, how to apply the above-mentioned method of detecting polarized light in multiple areas of the sky based on atmospheric detection points to an underwater environment, so that the number and types of polarization analysis channels used by the detection device or system can be further reduced on the basis of ensuring the accuracy of polarization light information detection at underwater detection points, while reducing the complexity of these channels for the polarization information processing process. Summary of the invention

[0007] In view of this, an embodiment of the present specification provides an underwater point source polarized light detection device and a method for measuring a heading angle thereof. The polarized light detection device has the advantages of good adaptability to underwater environments and uses a small number and type of polarization analysis channels. The method for measuring a heading angle has the advantages of high measurement accuracy and controllable costs.

[0008] This manual provides the following technical solutions:

[0009] First, an underwater point source polarized light detection device is provided, comprising a base, a rotating detection platform arranged on the base, and three groups of polarized light detection modules arranged on the top of the rotating detection platform, wherein one group of detection modules is used to receive and detect zenith polarized light, and the other two groups of detection modules are used to receive and detect zenith right side polarized light and zenith left side polarized light, respectively. The three groups of polarized light detection modules adopt the same structure and each group of detection modules is composed of a pair of polarization analysis channels with mutually perpendicular transmission directions. The other two groups of detection modules are positioned so that the polarized light detection directions of the two are left-right symmetrical about the zenith polarized light detection direction in the same plane and the angles between the two and the zenith polarized light detection direction do not exceed 5°. The rotating detection platform is configured to be able to rotate 360° around the axis where the zenith polarized light detection direction is located.

[0010] In order to optimize the above scheme, the following measures are also taken:

[0011] As a preferred embodiment, the pair of polarization analysis channels are polarization analysis channels with transmission directions of 0° and 90° respectively, wherein the polarization analysis channels include a polarization analyzer and a light intensity detection component and a voltage detection component electrically connected to the polarization analyzer.

[0012] As a preferred embodiment, the top of the rotating detection platform has a reference plane, a left mounting surface and a right mounting surface arranged in an isosceles trapezoid, the reference plane is located at the upper base of the isosceles trapezoid, the left mounting surface and the right mounting surface are respectively located at the side waists of the isosceles trapezoid, wherein the detection module for detecting zenith polarized light is arranged on the reference plane, the detection module for detecting the left side polarized light of the zenith is arranged on the left mounting surface, and the detection module for detecting the right side polarized light of the zenith is arranged on the right mounting surface.

[0013] A heading angle measurement method for measuring the heading angle of an underwater carrier using the underwater point source polarized light detection device is also provided. The base of the polarized light detection device is horizontally fixed on the underwater carrier. The heading angle measurement method comprises the following steps:

[0014] S1, determining a reference direction for calculating the heading angle of the underwater carrier, and selecting a reference polarization detection channel from the paired polarization detection channels in each polarization detection module, wherein the selected reference polarization detection channels all have the same vibration transmission direction, and in an initial state, the vibration transmission directions of all reference polarization detection channels are arranged to be parallel to the reference direction;

[0015] S2, control the rotating detection platform to rotate continuously in the horizontal direction and collect the detection voltages corresponding to the detection channels on the rotating detection platform in real time until the difference between the detection voltages of each pair of detection channels reaches the maximum, and record the rotation angle of the rotating detection platform relative to the reference direction at this time ;

[0016] S3, combined with rotation angle Or the rotation angle The angle between the projection lines of the reference direction relative to the solar meridian and the anti-solar meridian at the corresponding detection point is calculated based on the perpendicular relationship between the paired polarization channels and the transmission direction. , and combined with the polarization information of the polarized light on the right and left sides of the zenith, the angle Correction is performed to obtain the angle between the reference direction and the solar meridian, that is, the heading angle In order to optimize the above scheme, the following measures are also taken:

[0017] As a preferred method, in S3, the Rayleigh scattering model and the correspondence between the polarization degree of polarized light and the detection voltage in the polarization detection channel are combined, and the detection voltage of the reference polarization detection channel in the polarization detection module on the right side of the zenith and the left side of the zenith is used to determine the specific direction of the solar meridian, so as to determine the angle Make corrections and obtain the heading angle , where the angle The value range is , the heading angle The value range is .

[0018] As a preferred embodiment, in S1 to S2, the vibration transmission directions of the paired polarization analysis channels are respectively , , And the initial state of the vibration direction is The detection channel of the detection channel is used as the reference detection channel, and the difference of the detection voltage between each pair of detection channels is maximized, while the detection voltage corresponding to the reference detection channel in each pair of detection channels is minimized.

[0019] As a preferred method, in S2, the difference between the detection voltages of each pair of detection channels is determined to be the maximum according to the following formula and the rotation angle at this time is recorded: :

[0020] ;

[0021] in, , , They correspond to the zenith, the right side of the zenith, and the left side of the zenith in the polarized light detection module. The detection voltage corresponding to the detection channel and the vibration direction is The detection voltage corresponding to the detection channel The logarithm of the ratio.

[0022] As a preferred method or , the heading angle is calculated according to the following relationship :

[0023] ;

[0024] in, is the detection voltage corresponding to the detection channel with a transmission direction of 0° in the detection module on the right side of the zenith, It is the detection voltage corresponding to the detection channel with a transmission direction of 0° in the detection module on the left side of the zenith.

[0025] As a preferred method, in S2, the difference between the detection voltages corresponding to each pair of detection channels is determined to be the maximum according to the following formula and the rotation angle at this time is recorded: :

[0026] ;

[0027] in, , , They correspond to the zenith, the right side of the zenith, and the left side of the zenith in the polarized light detection module. The detection voltage corresponding to the detection channel and the vibration direction is The detection voltage corresponding to the detection channel The logarithm of the ratio.

[0028] As a preferred manner, in S2, the difference of the detection voltages corresponding to each pair of detection channels is maximized, and at the same time, the detection voltage corresponding to the reference detection channel in each pair of detection channels is maximized.

[0029] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0030] First, the underwater point source polarized light detection device has three groups of polarized light detection modules. The polarized light detection directions of the polarized light detection modules on the left and right sides of the zenith are tilted within 5° relative to the polarized light detection direction of the polarized light detection module on the zenith in the same plane, which means that the polarized light detection modules on the left and right sides of the zenith only receive polarized light information on the left and right sides of the zenith in the local window where the refraction angle is within the range of 5°. In this window, the underwater polarization mode detected by the detection module is almost the same as the atmospheric polarization mode detected by the corresponding atmospheric detection point, which makes the application scope of the method for measuring heading angle based on the atmospheric polarization mode in multiple occasions expand to the underwater environment. In addition, each polarized light detection module only uses two polarization detection channels with mutually perpendicular transmission directions to detect polarized light, and the number and type of detection light channels are relatively small, which makes the structure of the detection device simpler, the processing of channel information more convenient and efficient, and can reduce the cost of heading angle measurement.

[0031] Furthermore, the heading angle measurement method in this embodiment can determine whether the reference detection channel is rotated to a position parallel or perpendicular to the solar meridian plane by only monitoring the magnitude and difference of the detection voltage values ​​of the paired detection channels in the three groups of polarized light detection modules, and the value range can be converted into the reference detection channel according to the rotation angle of the rotating detection platform. The initial heading angle of the underwater carrier is the angle , and combined with the distribution law of polarization degree on both sides of the solar meridian and the anti-solar meridian under the Rayleigh scattering model, the angle The range of values ​​is extended to , thereby solving the 180-degree ambiguity problem in the heading angle measurement process. Not only does it require fewer solution steps and the type of variables that need to be monitored during the measurement process is single, it is convenient for the consistency and deterministic analysis of the parameters in each deviation detection channel, thereby improving the accuracy and reliability of the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 is a schematic structural diagram of the polarized light detection device in the first embodiment in a rotating state;

[0034] Figure 2 is a schematic cross-sectional structure diagram of the polarized light detection device in Example 1;

[0035] Figure 3 is a schematic diagram of the internal structure of the zenith polarized light detection module in the initial state in Example 1;

[0036] Figure 4 is a diagram showing the relationship between the rotation angle of the polarized light detection device and the position of the solar meridian in the first embodiment;

[0037] Figure 5 is the rotation angle of the polarized light detection device in Example 1 Positional relationship diagram between the post-zenith polarized light detection module and the projection line of the solar meridian on the detection point;

[0038] Figure 6 is the rotation angle of the polarized light detection device in the second embodiment Positional relationship diagram between the post-zenith polarized light detection module and the projection line of the solar meridian on the detection point;

[0039] Figure 7 It is a schematic diagram of the refraction path of atmospheric polarized light from the air medium into the underwater target detection point;

[0040] Figure 8 3 is a curve diagram showing the change of the polarization angle correlation coefficient with the refraction angle in the first embodiment.

[0041] 100, polarized light detection device; 10a, zenith polarized light detection module; 101a, 0° analysis channel; 101b, 90° analysis channel; 10b, zenith right polarized light detection module; 10c, zenith left polarized light detection module; 1, base; 2, rotating detection table; 21, reference plane; 22, right mounting surface; 23, left mounting surface; 3, acrylic sealing cover. DETAILED DESCRIPTION

[0042] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0043] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0044] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0045] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0046] The embodiments of this specification propose an underwater point source polarization light detection device and a heading angle measurement method thereof, aiming to solve the problem that the prior art method for detecting polarized light in multiple areas of the sky based on atmospheric detection points cannot be applied to underwater environments and the structure of the polarization light detection device used is complex. Not only can the polarization light information detected at the underwater detection point be accurately restored to the polarization light information detected at the corresponding detection point in the atmosphere, but also the number and types of polarization analysis channels used are relatively small, thereby reducing the complexity of the polarization light detection information processing process.

[0047] The specific implementation scheme of the polarized light detection device and the heading angle measurement method will be described in detail below with reference to the accompanying drawings.

[0048] Embodiment 1

[0049] like Figure 1 and Figure 2 As shown, in this embodiment, the underwater point source polarized light detection device 100 includes a base 1, a rotating detection platform 2 arranged on the base 1, and three groups of polarized light detection modules arranged on the top of the rotating detection platform 2, wherein one group of detection modules, namely the zenith polarized light detection module 10a, is used to receive and detect zenith polarized light, and the other two groups of detection modules, namely the zenith right polarized light detection module 10b and the zenith left polarized light detection module 10c, are respectively used to receive and detect the zenith right and zenith left polarized light, the three groups of polarized light detection modules adopt the same structure and each group of detection modules is composed of a pair of polarization analysis channels with mutually perpendicular transmission directions, the other two groups of detection modules are positioned so that the polarized light detection directions of the two are left-right symmetrical about the zenith polarized light detection direction in the same plane and the angles between them and the zenith polarized light detection direction do not exceed 5°, and the rotating detection platform is configured to be able to rotate 360° around the axis where the zenith polarized light detection direction is located.

[0050] In the present embodiment, the pair of polarization analysis channels are polarization analysis channels with transmission directions of 0° and 90° respectively. In other embodiments, for example, polarization analysis channels with transmission directions of 60° and 150° respectively or polarization analysis channels with transmission directions of 45° and 135° respectively may also be used. The polarization analysis channel includes an analyzer and a light intensity detection component and a voltage detection component electrically connected to the analyzer. The transmission direction mentioned here refers to the angle between the light transmission axis of the analyzer and its reference direction. The light intensity detection component includes a photodiode installed below the corresponding analyzer. The photodiode can generate a response current to the spectrum within the wavelength range of the polarized light of the underwater target detection point. The voltage detection component is connected to the output node of the photodiode for collecting a voltage value reflecting the light intensity. The photodiode senses the light intensity after the analyzer and converts it into a measurable voltage at the node. Then the voltage detection component can collect the voltage value.

[0051] like Figure 1 and Figure 2As shown, as an embodiment, the top of the rotating detection platform 2 has a reference plane 21, a left mounting surface 23 and a right mounting surface 22 arranged in an isosceles trapezoid, the reference plane is located at the upper bottom position of the isosceles trapezoid, the left mounting surface 23 and the right mounting surface 22 are respectively located at the side waist positions of the isosceles trapezoid, wherein the zenith polarized light detection module 10a is arranged on the reference plane 21, the zenith left polarized light detection module 10c is arranged on the left mounting surface 23, and the zenith right polarized light detection module 10b is arranged on the right mounting surface 22. In other embodiments, the top of the rotating detection platform 2 can also be set to a spherical shape or other forms, as long as the polarized light detection directions on both sides of the zenith are left-right symmetrical about the zenith polarized light detection direction in the same plane and the angles between them and the zenith polarized light detection direction do not exceed 5°. Preferably, each polarized light detection module is covered by a transparent acrylic sealing cover 3 installed on the corresponding plane, and the rotating detection platform 2 has a watertight installation cavity for installing a control module and a power module electrically connected to the polarization detection channel. The bottom of the watertight installation cavity is connected to the base 1 through a turntable, and a watertight plug interface electrically connected to the power module is also provided on the side wall of the rotating detection platform 2.

[0052] In the present embodiment, since the polarization light detection directions of the polarization light detection modules on the right side and the left side of the zenith are tilted within no more than 5° relative to the polarization light detection direction of the zenith polarization light detection module in the same plane, it means that the polarization light detection modules on the left and right sides of the zenith only receive the polarization light information on the left and right sides of the zenith in this local window where the refraction angle is within the range of 5°, and within this window, the polarization angle of the underwater polarized light detected by the detection module is almost consistent with the polarization angle of the atmospheric polarized light detected by the corresponding atmospheric detection point, which makes it possible to better expand the application scope of the method for measuring heading angles based on the atmospheric polarization mode to the underwater environment in multiple occasions.

[0053] like Figure 7 As shown, suppose that sunlight is scattered after passing through gas particles, aerosols and other particles in the atmosphere, producing polarized light , and then refracted on the water surface to produce polarized light in the Snell window , passed into the target detection module. Here, is the wave vector of atmospheric scattered light, is the polarization direction vector of the atmospheric scattered light, is the Stokes vector of the atmospheric scattered light, is the wave vector of underwater refracted light, is the polarization direction vector of the underwater refracted light, is the Stokes vector of refracted light underwater. The air-water interface is represented by the interface normal vector n and the true refractive index of air and water and Definition. Here, is the incident angle of polarized light, is the refraction angle of polarized light, The refractive index of water is 1.33, The refractive index of air is 1. According to the law of refraction, the Stokes vector of the polarized light measured at the underwater target detection point is Stokes vector of atmospheric polarized light measured at the corresponding detection point in the air The relationship is: , where the Mueller matrix It can be calculated by the following formula:

[0054] ;

[0055] in, are the refraction process parameters, which can be calculated by the following formulas:

[0056] , ;

[0057] Among them, from the above, we know that is the wave vector of underwater refracted light, which can be calculated by the following formula:

[0058] ;

[0059] in, Represents wave vector The model, is the wave vector of the transmitted light from the air medium into the water medium, Represents wave vector Model. It can be calculated by the following formula:

[0060] ;

[0061] here, , ,in and are the total intensity of scattered light and underwater refracted light, and are the Stokes components of the scattered light in two mutually perpendicular directions, and are the Stokes components of the refracted light in two mutually perpendicular directions. According to the calculation formula of the polarization angle of polarized light, the atmospheric polarization angle before refraction and the refraction angle of the polarized light at the underwater observation point after refraction They can be calculated by the following formulas:

[0062] , ;

[0063] Therefore, the atmospheric polarization angle before refraction is Polarization angle observed in water after refraction The relationship can be Given, here we assume , is the polarization angle correlation coefficient. With the refraction angle The changing trends, such as Figure 8 As shown, the refraction angle hour, , which can be approximated to 1. The polarization angle of a certain observation point observed in water within this refraction angle range is basically equal to the polarization angle of the point observed at the corresponding observation point in the air. It can be considered that the polarization mode in water and the atmospheric polarization mode are consistent within this small window range, which means that the polarization light components in each polarization analysis channel at the detection point receiving the refracted polarized light will hardly change, and the polarization direction of the underwater polarized light is still roughly perpendicular to the solar meridian. This makes the heading angle measurement methods such as obtaining the solar vector by vector cross multiplication designed according to the atmospheric polarization mode or obtaining the specific orientation of the solar meridian based on the comparison of the atmospheric polarization light components well applicable to the underwater environment and obtain high-precision measurement results.

[0064] This embodiment further discloses a heading angle measurement method for measuring the heading angle of an underwater carrier using the underwater point source polarized light detection device. The base 1 of the polarized light detection device is horizontally fixed on the underwater carrier. The heading angle measurement method comprises the following steps:

[0065] S1. Determine a reference direction for calculating the heading angle of the underwater carrier. Here, the reference direction is required to have a fixed angle difference with the forward direction of the underwater carrier, and select a reference polarization detection channel from the paired polarization detection channels in each polarization detection module. The selected reference polarization detection channels all have the same vibration transmission direction. In the initial state, the vibration transmission directions of all reference polarization detection channels are arranged to be parallel to the reference direction. Here, the vibration transmission directions of the paired polarization detection channels are respectively , , And the initial state of the vibration direction is The polarization detection channel is used as the reference polarization detection channel.

[0066] S2, control the rotating detection platform to rotate continuously in the horizontal direction and collect the detection voltages corresponding to the detection channels on the rotating detection platform 2 in real time until the difference between the detection voltages of each pair of detection channels reaches the maximum, and record the rotation angle of the rotating detection platform relative to the reference direction at this time .

[0067] The difference here refers to the difference in the value of the detection voltage, for example, it can be measured by the absolute value of the difference in the detection voltage between each pair of polarization detection channels. The reason for maximizing the difference is that, taking the zenith polarization light detection module 10a as an example, during the rotation of the rotating detection platform 2, when the transmission direction of one of the paired polarization detection channels with mutually perpendicular transmission directions is parallel to the solar meridian and the transmission direction of the other polarization detection channel is perpendicular to the solar meridian, the distribution of atmospheric polarized light has the following rule, that is, the polarization direction at the solar meridian and the anti-solar meridian is different from that at the solar meridian and the anti-solar meridian. The solar meridian is vertical. It has been explained before that this law is also applicable to the underwater carrier using the underwater point source polarization light detection device, that is, for the polarization light detection points on the right and left sides of the zenith, the distribution of underwater polarized light also follows the above law, which will not be elaborated here. Therefore, at this time, the intensity of the polarized light transmitted through the above-mentioned polarization channel parallel to the solar meridian reaches the minimum, while the intensity of the polarized light transmitted through the other polarization channel reaches the maximum. The intensity value of the polarized light is positively correlated with the detection voltage value, so the difference in the intensity value reaches the maximum, which means that the difference in the detection voltage value will reach the maximum. Conversely, when the difference in the detection voltage value reaches the maximum, it can be determined that there must be a polarization channel with a transmission direction parallel to the solar meridian, while the transmission direction of the other polarization channel is perpendicular to the solar meridian.

[0068] S3, combined with rotation angle Or the rotation angle The angle between the projection lines of the reference direction relative to the solar meridian and the anti-solar meridian at the corresponding detection point is calculated based on the perpendicular relationship between the paired polarization channels and the transmission direction. , and combined with the polarization information of the polarized light on the right and left sides of the zenith, the angle Correction is performed to obtain the angle between the reference direction and the solar meridian, that is, the heading angle .

[0069] Specifically, in S2, the difference between the detection voltages of each pair of detection channels is determined to be the maximum according to the following formula and the rotation angle at this time is recorded: :

[0070] ;

[0071] in, , , They correspond to the zenith, the right side of the zenith, and the left side of the zenith in the polarized light detection module. The detection voltage corresponding to the detection channel and the vibration direction is The detection voltage corresponding to the detection channel The logarithm of the ratio means that in the three sets of polarized light detection modules, when the detection voltage reaches a minimum and detects the voltage When the maximum value is reached, record the rotation angle .

[0072] like Figure 5 As shown, as one of the ways, the difference of the detection voltage between each pair of detection channels is maximized while the detection voltage corresponding to the reference detection channel in each pair of detection channels is minimized. When the detection voltage corresponding to the reference detection channel in each pair of detection channels is minimized, the vibration transmission direction of the reference detection channel is parallel to the solar meridian or the solar meridian plane. Since in the initial state, the vibration transmission direction of the reference detection channel is parallel to the reference direction, and at this time, the rotation angle of the rotating detection platform 2 relative to the reference direction is , that is, the rotation angle of the reference polarization channel in the direction of vibration , based on which the angle between the reference direction and the projection line of the detection point where the solar meridian and the anti-solar meridian are located can be calculated .

[0073] In S3, the Rayleigh scattering model and the correspondence between the polarization degree of polarized light and the detection voltage in the polarization detection channel are combined, and the detection voltage of the reference polarization detection channel in the polarization detection module on the right side and the left side of the zenith is used to determine the specific position of the solar meridian, so as to determine the angle Make corrections and obtain the heading angle , where the angle The value range is , the heading angle The value range is Specifically, under the Rayleigh scattering model, the degree of polarization on one side of the solar meridian is greater than that on the other side of the solar meridian. According to the corresponding relationship between the degree of polarization of polarized light and the detection voltage in the polarization analysis channel, the relationship between the total light intensity and the degree of polarization of the incident light after the reference polarization analysis channel in the polarization light detection module on the right side and the left side of the zenith is converted into the relationship between the detection voltage and the degree of polarization of the incident light. Then, by comparing the magnitudes of the detection voltages of the two reference polarization analysis channels, the specific orientation of the solar meridian can be determined.

[0074] like Figure 3 , Figure 4 and Figure 5 As shown, in this embodiment, the paired polarization channels include a 0° polarization channel 101a with a transmission direction of 0° and a 90° polarization channel 101b with a transmission direction of 90°, and a body coordinate system of the underwater carrier is established, wherein The arrow direction of the axis is the positive direction, which is also the reference direction of the underwater carrier. Axis and Axis vertical, coordinate system The axis is parallel to the transmission direction of the 0° analyzer channel 101a. Assuming that the polarization direction of the detected zenith polarized light is the same as that of the 0° analyzer channel 101a coordinate system, Axis angle, according to Malus's law, the light intensity I , polarization degree d After the partially polarized light passes through the two polarization analysis channels, the non-polarized light intensity Both are:

[0075] ;

[0076] The intensity of the linearly polarized light after the two polarization analysis channels is:

[0077] ;

[0078] in, , They are respectively the linear polarized light intensities after the 0° polarization analysis channel 101a and the 90° polarization analysis channel 101b.

[0079] After trigonometric transformation, the total light intensity sensed by each photodiode is:

[0080] ;

[0081] Assume that when the rotating detection platform 2 rotates Angle, calculate the following formula:

[0082] ;

[0083] in, and are the voltage values ​​collected by the voltage detection components of the 0° detection channel 101a and the 90° detection channel 101b, respectively. The voltage value is proportional to the total light intensity after the detection channel. , , They correspond to the zenith, the right side of the zenith, and the left side of the zenith in the polarized light detection module. The detection voltage corresponding to the detection channel and the vibration direction is The detection voltage corresponding to the detection channel The logarithm of the ratio. The 0° polarization channels in the three detection modules are parallel to the solar meridian. or . Then the rotation angle = , That is, the angle at this time , then the solar meridian and The angle between the axes is or ,Right now or ; The sun's position may be Figure 4 point a or point b in .

[0084] In order to solve the 180° ambiguity problem in the above detection results, the detection voltage corresponding to the detection channel with a transmission direction of 0° in the detection module on the right side of the zenith is obtained respectively. , the detection voltage corresponding to the detection channel with a transmission direction of 0° in the left detection module of the zenith , according to the above relationship between the total light intensity and polarization degree of the 0° analyzer channel, substitute or , it is determined that the total light intensity of the 0° analyzer channel is inversely proportional to the degree of polarization, so the detection voltage of the analyzer channel is also inversely proportional to the degree of polarization. The heading angle is calculated based on the distribution law of the atmospheric polarization degree on both sides of the solar meridian and the anti-solar meridian. :

[0085] ;

[0086] This solves the 180° ambiguity problem in the heading angle measurement process, that is, the angle The value range of Expand to , realizing the full heading angle measurement of the underwater carrier.

[0087] As another implementation, in S2, the difference between the detection voltages corresponding to each pair of detection channels is determined to be the maximum according to the following formula and the rotation angle at this time is recorded: :

[0088] ;

[0089] in, , , They correspond to the zenith, the right side of the zenith, and the left side of the zenith in the polarized light detection module. The detection voltage corresponding to the detection channel and the vibration direction is The detection voltage corresponding to the detection channel The logarithm of the ratio.

[0090] Here, the formula used to calculate the difference in detection voltage between each pair of detection channels is similar to the above calculation. The idea of ​​the minimum value of is different, but the concept of the two is the same, that is, both record the rotation angle when the ratio of the detection voltage between the detection channels reaches an extreme value. , and when the ratio of the detection voltages between the detection channels reaches an extreme value, it means that the difference in detection voltages reaches a maximum. At this time, the transmission direction of one of the detection channels is parallel to the solar meridian, while the other detection channel is perpendicular to the solar meridian. Then, according to this rule, the angle is obtained. The value range of .

[0091] Embodiment 2

[0092] The difference between this embodiment and the first embodiment is that in S2, the difference between the detection voltages corresponding to each pair of detection channels is maximized, and at the same time, the detection voltage corresponding to the reference detection channel in each pair of detection channels is maximized. Figure 6 As shown, the paired detection channels are still taken as 0° detection channel 101a and 90° detection channel 101b for explanation. At this time, the reference detection channel is selected as 0° detection channel 101a. Then, the differences of the detection voltages corresponding to the detection channels are maximized and the detection voltage of 0° detection channel 101a is maximized. This means that at this time, the transmission direction of 0° detection channel 101a is perpendicular to the solar meridian direction, while that of 90° detection channel 101b is parallel to the solar meridian direction. Since the positional relationship between the transmission directions of the two detection channels and the solar meridian direction has been obtained, the angle can be obtained. Then, the heading angle is calculated based on the distribution law of the atmospheric polarization degree on both sides of the solar meridian and the anti-solar meridian. , thereby also being able to achieve measurement of the full heading angle, the remaining parts not described are the same as those in Embodiment 1 and will not be described in detail here.

[0093] In summary, the heading angle measurement method in this embodiment can determine whether the reference polarization channel is rotated to a position parallel to or perpendicular to the solar meridian plane, i.e., the plane where the solar meridian and the anti-solar meridian are located, by only monitoring the magnitude and difference of the detection voltage values ​​of the paired polarization channels in the three groups of polarized light detection modules. Combined with the rotation angle of the reference polarization channel along with the rotating detection platform 2, the value range can be converted to Angle The value of , and combined with the distribution law of polarization degree on both sides of the solar meridian and the anti-solar meridian under the Rayleigh scattering model, the angle The range of values ​​is extended to , thereby solving the 180-degree ambiguity problem in the heading angle measurement process. Not only does it require fewer solution steps, but it also requires a single type of variable to be monitored during the measurement process. That is, accurate measurement of the full heading angle can be achieved by only monitoring the detection voltage of each detection channel, which facilitates the consistency and deterministic analysis of the parameters in each detection channel, thereby improving the accuracy and reliability of the measurement results.

[0094] Moreover, each polarized light detection module on the rotating detection platform 2 only uses two polarization analysis channels whose transmission directions are perpendicular to each other to detect polarized light. Compared with the prior art, while achieving the technical purpose of measuring the full heading angle of the underwater carrier, the number and types of detection light channels used are relatively small, which makes the structure of the detection device simpler, and the processing of the information of each polarization analysis channel is simpler and more efficient, which can reduce the cost of heading angle measurement.

[0095] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments.

[0096] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An underwater point source polarized light detection device, characterized in that: It includes a base, a rotating detection platform arranged on the base, and three groups of polarized light detection modules arranged on the top of the rotating detection platform, wherein one group of detection modules is used to receive and detect zenith polarized light, and the other two groups of detection modules are used to receive and detect polarized light on the right side of the zenith and on the left side of the zenith, respectively. The three groups of polarized light detection modules adopt the same structure and each group of detection modules is composed of a pair of polarization analysis channels with mutually perpendicular transmission directions. The other two groups of detection modules are positioned so that the polarized light detection directions of the two are left-right symmetrical about the zenith polarized light detection direction in the same plane and the angles between them and the zenith polarized light detection direction do not exceed 5°. The rotating detection platform is configured to be able to rotate 360° around the axis where the zenith polarized light detection direction is located.

2. The underwater point source polarized light detection device according to claim 1, characterized in that: The pair of polarization analysis channels are polarization analysis channels with transmission directions of 0° and 90° respectively, wherein the polarization analysis channels include a polarization analyzer and a light intensity detection component and a voltage detection component electrically connected to the polarization analyzer.

3. The underwater point source polarized light detection device according to claim 1, characterized in that: The top of the rotating detection platform has a reference plane, a left mounting surface and a right mounting surface arranged in an isosceles trapezoid, the reference plane is located at the upper base of the isosceles trapezoid, the left mounting surface and the right mounting surface are respectively located at the side waist positions of the isosceles trapezoid, wherein the detection module for detecting zenith polarized light is arranged on the reference plane, the detection module for detecting the left side polarized light of the zenith is arranged on the left mounting surface, and the detection module for detecting the right side polarized light of the zenith is arranged on the right mounting surface.

4. A method for measuring a heading angle of an underwater carrier using the underwater point source polarized light detection device as claimed in any one of claims 1 to 3, wherein the base of the polarized light detection device is horizontally fixed on the underwater carrier, characterized in that: The heading angle measurement method comprises the following steps: S1, determining a reference direction for calculating the heading angle of the underwater carrier, and selecting a reference polarization detection channel from the paired polarization detection channels in each polarization detection module, wherein the selected reference polarization detection channels all have the same vibration transmission direction, and in an initial state, the vibration transmission directions of all reference polarization detection channels are arranged to be parallel to the reference direction; S2, control the rotating detection platform to rotate continuously in the horizontal direction and collect the detection voltages corresponding to the detection channels on the rotating detection platform in real time until the difference between the detection voltages of each pair of detection channels reaches the maximum, and record the rotation angle of the rotating detection platform relative to the reference direction at this time ; S3, combined with rotation angle Or the rotation angle The angle between the projection lines of the reference direction relative to the solar meridian and the anti-solar meridian at the corresponding detection point is calculated based on the perpendicular relationship between the paired polarization channels and the transmission direction. , and combined with the polarization information of the polarized light on the right and left sides of the zenith, the angle Correction is performed to obtain the angle between the reference direction and the solar meridian, that is, the heading angle .

5. The heading angle measurement method according to claim 4, characterized in that: In S3, the Rayleigh scattering model and the correspondence between the polarization degree of polarized light and the detection voltage in the polarization detection channel are combined, and the detection voltage of the reference polarization detection channel in the polarization detection module on the right side and the left side of the zenith is used to determine the specific position of the solar meridian, so as to determine the angle Make corrections and obtain the heading angle , where the angle The value range is , the heading angle The value range is .

6. The heading angle measurement method according to claim 4, characterized in that: In S1 to S2, the vibration transmission directions of the paired polarization analysis channels are respectively , , And the initial state of the vibration direction is The detection channel of the detection channel is used as the reference detection channel, and the difference of the detection voltage between each pair of detection channels is maximized, while the detection voltage corresponding to the reference detection channel in each pair of detection channels is minimized.

7. The heading angle measurement method according to claim 6, characterized in that: In S2, the difference between the detection voltages of each pair of detection channels is determined to be the maximum according to the following formula and the rotation angle at this time is recorded: : ； in, , , They correspond to the zenith, the right side of the zenith, and the left side of the zenith in the polarized light detection module. The detection voltage corresponding to the detection channel and the vibration direction is The detection voltage corresponding to the detection channel The logarithm of the ratio.

8. The heading angle measurement method according to claim 5 or 6, characterized in that: Pick but , the heading angle is calculated according to the following relationship : ； in, is the detection voltage corresponding to the detection channel with a transmission direction of 0° in the detection module on the right side of the zenith, It is the detection voltage corresponding to the detection channel with a transmission direction of 0° in the detection module on the left side of the zenith.

9. The heading angle measurement method according to claim 6, characterized in that: In S2, the difference between the detection voltages corresponding to each pair of detection channels is determined to be the maximum according to the following formula and the rotation angle at this time is recorded: : ； in, , , They correspond to the zenith, the right side of the zenith, and the left side of the zenith in the polarized light detection module. The detection voltage corresponding to the detection channel and the vibration direction is The detection voltage corresponding to the detection channel The logarithm of the ratio.

10. The heading angle measurement method according to claim 4, characterized in that: In S2, the difference of the detection voltages corresponding to each pair of detection channels is maximized, and at the same time, the detection voltage corresponding to the reference detection channel in each pair of detection channels is maximized.

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