Polarized light orientation method based on Rayleigh point information

Abstract

The invention discloses a polarized light orientation method based on Rayleigh point information, and the method comprises the steps: collecting a sky polarization image, and carrying out the calculation to obtain an actually-measured polarization angle of each measurement point in the sky polarization image of a measurement point; calculating an ideal polarization angle of each measurement point in the sky polarization image of the measurement point, and obtaining a polarization angle error of each measurement point based on the actually measured polarization angle of the measurement point and the ideal polarization angle of the measurement point; and screening out Rayleigh points in all the measurement points based on the polarization angle errors of the measurement points, and carrying out polarized light orientation based on all the Rayleigh points to obtain the course angle of the carrier. The method is applied to the field of polarized light navigation, the actually-measured polarization angle and the theoretical polarization angle of each measurement point are compared before polarized light orientation, the Rayleigh point in the sky polarization image is screened out based on the polarization angle error between the actually-measured polarization angle and the theoretical polarization angle, and polarized light orientation is carried out only through the screened Rayleigh point. Therefore, the polarized light orientation precision is obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of polarized light navigation, in particular to a polarized light orientation method based on Rayleigh point information. Background Art

[0002] Accurate positioning information is the basis for autonomous navigation of long-flight unmanned platforms. However, in the case of satellite stoppage or complex electromagnetic interference environment, the existing inertial navigation has error accumulation and geomagnetic navigation is easily interfered, which cannot meet the requirements of high-precision navigation of unmanned platforms.

[0003] During the propagation process, sunlight is absorbed and scattered by atmospheric particles to produce polarized light. A large amount of polarized light converges in the sky to form an atmospheric polarization pattern with a certain distribution pattern. The atmospheric polarization pattern contains directional information. Based on the geometric property that the polarized light E vector is perpendicular to the scattering surface in the Rayleigh scattering model, the carrier azimuth can be estimated by measuring the atmospheric polarization information. It can be seen that Rayleigh scattering is an important theoretical method for studying the characterization of atmospheric polarization patterns, but it only occurs when the particle size is much smaller than the wavelength of the incident light, which makes it difficult for Rayleigh scattering theory to explain the influence of other particles such as water vapor and aerosols on the scattering process. Moreover, due to the complexity of weather, it is impossible to use a single scattering model to describe any type of weather. Even on sunny days, there are other scatterings besides Rayleigh scattering, especially on sunny days with obstructions, few clouds, cloudy or overcast weather, which leads to increased directional errors. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a polarized light orientation method based on Rayleigh point information, which can effectively improve the accuracy of polarized light orientation.

[0005] To achieve the above object, the present invention provides a polarized light orientation method based on Rayleigh point information, comprising the following steps:

[0006] Step 1, collecting a sky polarization image based on a polarization compass on a carrier, and calculating the measured polarization angle of each measurement point in the sky polarization image;

[0007] Step 2, calculating the ideal polarization angle of each measurement point in the sky polarization image, and obtaining the polarization angle error of each measurement point based on the measured polarization angle and the ideal polarization angle;

[0008] Step 3: Screen out Rayleigh points from all measurement points based on the polarization angle error, and perform polarization light orientation based on all Rayleigh points to obtain the heading angle of the carrier.

[0009] In one embodiment, in step 1, the calculation process of the measured polarization angle is:

[0010] Stokes Vector S0 Contains four parameters S 0 =[S 1 S 2 S 3 S 4 ], where S 1 Represents the total light intensity, S 2 is the light intensity difference between 0° and 90°, S 3 is the light intensity difference between 45° and 135°, S 4 is the circular polarization component, then the intensity of polarized light after passing through the polarizer is:

[0011]

[0012] Among them, θ 1 is the polarization angle, is the angle between the sensor polarization direction and the system optical axis;

[0013] S 4 The components are omitted, and the simplified Stokes strength equation is:

[0014]

[0015] When the polarization angle θ 1 When taking 0°, 45°, and 90° respectively, the Stokes parameters of the measurement point are:

[0016]

[0017] Without considering circularly polarized light, the measured polarization angle at the measurement point is φ a =(1 / 2)·arctan(S 3 / S 2 ).

[0018] In one embodiment, in step 2, the calculation process of the ideal polarization angle is:

[0019] Calculate the projection v of the observation direction vector v of the measurement point on the optical compass coordinate system c ,for:

[0020] v c =[sinγ v ·cosα v sinγ v ·sinα v -cosγ v ] T

[0021] Among them, T is the transpose of the matrix, α v is the azimuth of the measuring point in the optical compass coordinate system, γv is the zenith angle of the measuring point in the optical compass coordinate system;

[0022] Calculate the projection s of the sun direction vector s on the optical compass coordinate system c ,for:

[0023]

[0024] in, is the transformation matrix from the carrier coordinate system to the optical compass coordinate system, is the transformation matrix from the navigation coordinate system to the optical compass coordinate system, s n is the sun direction vector in the navigation coordinate system;

[0025] Based on the projection v of the observation direction vector v and the sun direction vector s on the optical compass coordinate system c 、s c , calculate the projection e of the E vector e of the measurement point on the optical compass coordinate system c ,for:

[0026] e c = k·v c ×s c

[0027] Where k is a constant that makes both sides of the equation equal;

[0028] The projection e of the E vector e of the measurement point on the optical compass coordinate system c Convert to the measurement point coordinate system:

[0029]

[0030] in, is the transformation matrix from the optical compass coordinate system to the measurement point coordinate system, e 1 、e 2 、e 3 is the vector e v In addition, the E vector e of the measuring point can also be expressed by the polarization angle in the measuring point coordinate system, which is:

[0031]

[0032] Therefore, the ideal polarization angle of the measurement point is φ b =arctan(e 2 / e 1 ).

[0033] In one embodiment, the transformation matrix distance from the carrier coordinate system to the optical compass coordinate system is:

[0034]

[0035] The conversion matrix from the navigation coordinate system to the optical compass coordinate system is specifically:

[0036]

[0037] Among them, r 0 ,θ 0 , 0 The rolling angle, pitch angle and heading angle of the carrier are provided by other sensors respectively;

[0038] The sun direction vector in the navigation coordinate system is specifically:

[0039]

[0040] in, is the azimuth of the sun direction vector in the navigation coordinate system, is the altitude angle of the sun direction vector in the navigation coordinate system.

[0041] In one embodiment, the constant k that makes both sides of the equation equal is specifically:

[0042]

[0043] Where τ is the scattering angle.

[0044] In one embodiment, in step 2, the polarization angle error is specifically:

[0045] Δφ=|φ a -φ b |

[0046] Among them, Δφ is the polarization angle error, φ a is the measured polarization angle, φ b is the ideal polarization angle.

[0047] In one embodiment, in step 3, the process of screening out Rayleigh points from all measurement points based on the polarization angle error is:

[0048] For any measurement point, determine whether its polarization angle error satisfies Δφ≤φ thres If so, the measurement point is a Rayleigh point, otherwise it is a non-Rayleigh point, where φ thres is the threshold value.

[0049] In one embodiment, the threshold φ thres =5°.

[0050] In one embodiment, in step 3, the process of performing polarization light orientation based on all Rayleigh points is:

[0051] Get the Rayleigh point set E consisting of all Rayleigh points c ,for:

[0052]

[0053] in, i = 1 ~ L is the projection of the E vector of the i-th Rayleigh point on the optical compass coordinate system, and L is the total number of Rayleigh points;

[0054] Rayleigh point set E c Each Rayleigh point in satisfies the orthogonality of polarization vectors, that is:

[0055]

[0056] in, i = 1 ~ l is the projection of the observation direction vector of the ith Rayleigh point on the optical compass coordinate system, s c is the projection of the sun direction vector on the optical compass coordinate system;

[0057] At the same time and place, different Rayleigh points correspond to different E vectors and different observation direction vectors, but the corresponding sun direction vector is unified. Therefore, the projection s of the sun direction vector on the optical compass coordinate system can be obtained by using the Lagrange multiplier method to solve the simultaneous equations of all Rayleigh points. c ;

[0058] In addition, the projection of the sun direction vector on the optical compass coordinate system can also be expressed as:

[0059]

[0060] Among them, α s is the azimuth of the sun direction vector in the optical compass coordinate system, h s is the zenith angle of the sun direction vector in the optical compass coordinate system;

[0061] Right now:

[0062]

[0063] Among them, s c (1)s c (2) Divided into vector s c The first and second elements in ;

[0064] Azimuth angle α based on the sun direction vector in the optical compass coordinate system s And the azimuth of the sun direction vector in the navigation coordinate system The heading angle of the carrier can be obtained as:

[0065]

[0066] or

[0067]

[0068] Among them, Ψ is the heading angle of the carrier, and π is the ambiguity of the polarization orientation.

[0069] Compared with the prior art, the present invention has the following beneficial technical effects:

[0070] The present invention compares the measured polarization angle of each measurement point with the theoretical polarization angle before polarized light orientation, and screens out the Rayleigh points in the sky polarization image based on the polarization angle error between the measured polarization angle and the theoretical polarization angle, and then performs polarized light orientation only through the screened Rayleigh points, thereby significantly improving the accuracy of polarized light orientation. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0072] Figure 1 Flow chart of a polarized light orientation method based on Rayleigh point information in an embodiment of the present invention;

[0073] Figure 2 Schematic diagram of the scattering process of sunlight in the sky in an embodiment of the present invention;

[0074] Figure 3 Schematic diagram of the effect of the Rayleigh point ratio on the orientation error in an embodiment of the present invention.

[0075] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0076] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0077] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0078] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0079] This embodiment discloses a polarization light orientation method based on Rayleigh point information, which compares the measured polarization angle of each measurement point with the theoretical polarization angle before polarization light orientation, and screens out the Rayleigh points in the sky polarization image based on the polarization angle error between the measured polarization angle and the theoretical polarization angle, and then only uses the screened Rayleigh points for polarization light orientation, thereby significantly improving the accuracy of polarization light orientation.

[0080] refer to Figure 1 In this embodiment, the polarized light orientation method based on Rayleigh point information specifically includes the following steps:

[0081] Step 1, collecting a sky polarization image based on a polarization compass on a carrier, and calculating the measured polarization angle of each measurement point in the sky polarization image;

[0082] Step 2, calculating the ideal polarization angle of each measurement point in the sky polarization image, and obtaining the polarization angle error of each measurement point based on the measured polarization angle and the ideal polarization angle;

[0083] Step 3: Screen out Rayleigh points from all measurement points based on the polarization angle error, and perform polarization light orientation based on all the Rayleigh points to obtain the heading angle of the carrier.

[0084] refer to Figure 2 Schematic diagram of the scattering process of sunlight in the sky, where O c represents the observer on the ground, V represents the measurement point in the sky, S represents the sun, Z represents the zenith, N represents the geographic north, τ represents the scattering angle, γ s , α s Represent the solar zenith angle and azimuth respectively, φ represents the polarization angle of the measurement point, α v represents the azimuth of the measuring point, γ v , α v Represents the zenith angle and azimuth of the measurement point V in the polarized light compass coordinate system.

[0085] In this embodiment, the right-front-upper coordinate system is defined as the polarized light compass coordinate system (hereinafter referred to as the "C system"), Xc Axis and Y c The axes point to the horizontal and vertical axes of the polarized light compass respectively, Z c The axis is the optical axis direction of the polarized light compass. After leveling, the Z c The axis points to the zenith. The north-east-earth coordinate system is defined as the navigation coordinate system (hereinafter referred to as the "n system"), and O n -X n Y n Z n Indicates that O n With O c coincide, Figure 2 For the sake of simplicity, Y is omitted. n Axis and Z n Axis, X n The axis direction is the geographic north. Figure 2 The front-right-bottom coordinate system is defined as the carrier coordinate system (hereinafter referred to as the "b system"), and O b -X b Y b Z b To represent, where O b With O c coincide, Figure 2 For the sake of simplicity, Y is omitted. b Axis and Z b Axis, the heading angle Ψ of the carrier is X b The angle between the axis and N. Define O v -X v Y v Z v is the measurement point coordinate system (hereinafter referred to as “v system”), Z v The axis points to the measuring point, X v The axis is located in the observation plane ΔO v VV', Y v The axis is known from the right-hand rule. Figure 2 For the sake of simplicity, Y is omitted. v Axis. e is the unit vector of the vibration direction of the polarized light E vector at the measuring point V, v is the unit vector of the observation direction, and s is the unit vector in the direction of the sun.

[0086] In this embodiment, the measured polarization angle of the measurement point can be calculated using the Stokes vector method. The Stokes vector includes four parameters S 0 =[S 1 S 2 S 3 S 4 ], where S 1 Represents the total light intensity, S 2 is the light intensity difference between 0° and 90°, S 3is the light intensity difference between 45° and 135°, S 4 is the circular polarization component, then the intensity of polarized light after passing through the polarizer is:

[0087]

[0088] Among them, θ 1 is the polarization angle, is the angle between the sensor polarization direction and the system optical axis;

[0089] Since there are very few circular polarization components in nature, S is usually used in actual calculations. 4 The components are omitted, and the simplified Stokes strength equation is:

[0090]

[0091] When the polarization angle θ 1 When taking 0°, 45°, and 90° respectively, the Stokes parameters of each pixel on the image are:

[0092]

[0093] Without considering circularly polarized light, the measured polarization angle at each measurement point is:

[0094]

[0095] Among them, φ a is the measured polarization angle of the measurement point.

[0096] In this embodiment, the ideal polarization angle of the measurement point is calculated based on the simulation model of the ideal atmospheric polarization mode, and the specific implementation process is as follows:

[0097] Depend on Figure 2 It can be seen that the projection v of the observation direction vector v on the c system c for:

[0098] v c =[sinγ v ·cosα v sinγ v ·sinα v -cosγ v ] T (5)

[0099] T is the transpose of the matrix, and the zenith angle γ of the measurement point in the c system v and azimuth α v Specifically:

[0100]

[0101] Among them, (x v ,y v ) is the coordinate of the observation point in the atmospheric polarization image, (x c ,y c ) is the coordinate of the center point of the atmospheric polarization image, f c is the focal length of the polarized light compass obtained through calibration;

[0102] The sun direction vector s can be expressed in the n system as:

[0103]

[0104] in, is the azimuth of the sun direction vector in the navigation coordinate system, is the altitude angle of the sun direction vector in the navigation coordinate system. When the time and geographical location are known, It can be obtained through the solar ephemeris;

[0105] Will s n Converted to C system:

[0106]

[0107] is the transformation matrix from b system to c system, expressed as:

[0108]

[0109] is the conversion matrix from n system to c system, expressed as:

[0110]

[0111] Among them, r 0 ,θ 0 , 0 The carrier roll angle, pitch angle and heading angle are provided by other sensors (such as dual satellite antennas) respectively;

[0112] According to the Rayleigh scattering theory, in the same coordinate system, the E vector of polarized light is perpendicular to the scattering surface, so the projection of the E vector e of the measurement point on the optical compass coordinate system is c for:

[0113] e c = k·v c ×s c (12)

[0114] k is a constant that makes both sides of the equation equal, expressed as:

[0115]

[0116] Where τ is the scattering angle;

[0117] The projection e of the E vector e of the measurement point obtained by equation (12) on the c system c Converting to the v system, we get:

[0118]

[0119] e 1 、e 2 、e 3 is the vector e v The three elements of is the transformation matrix from the optical compass coordinate system to the measurement point coordinate system, expressed as:

[0120]

[0121] In addition, the E vector e of the measuring point can also be expressed by the ideal polarization angle in the measuring point coordinate system, which is:

[0122]

[0123] Combining equations (15) and (17), we can get the ideal polarization angle of the measurement point as φ b =arctan(e 2 / e 1 ).

[0124] According to the calculation process of the ideal polarization angle, it can be known that when the geographical location, time and carrier attitude angle are determined, the ideal polarization angle of the measurement point in the current state can be obtained.

[0125] After respectively calculating the measured polarization angle and the ideal polarization angle of the measurement point, the polarization angle error can be calculated. The polarization angle error in this embodiment is specifically:

[0126] Δφ=|φ a -φ b | (18)

[0127] Where Δφ is the polarization angle error.

[0128] In step 3, the process of selecting Rayleigh points from all measurement points based on polarization angle error is as follows: for any measurement point, determine whether its polarization angle error satisfies:

[0129] Δφ≤φ thres (19)

[0130] Among them, φ thres is the threshold value;

[0131] If yes, the measurement point is a Rayleigh point, otherwise it is a non-Rayleigh point. In this embodiment, the threshold φ is set thres =5°.

[0132] After the Rayleigh points are screened, polarized light orientation can be performed based on all the Rayleigh points. The specific implementation process is as follows:

[0133] Assuming that there are L Rayleigh points screened out, first obtain the Rayleigh point set E consisting of all Rayleigh points c ,for:

[0134]

[0135] in, i = 1 ~ L is the projection of the E vector of the i-th Rayleigh point on the optical compass coordinate system;

[0136] Rayleigh point set E c Each Rayleigh point in satisfies the orthogonality of polarization vectors, that is:

[0137]

[0138] in, i = 1 ~ L is the projection of the observation direction vector of the i-th Rayleigh point on the optical compass coordinate system;

[0139] From formula (20), we can see that at the same time and place, different Rayleigh points correspond to different E vectors and different observation direction vectors, but the corresponding sun direction vector is unified. Therefore, the projection s of the sun direction vector on the optical compass coordinate system can be obtained by using the Lagrange multiplier method to solve the simultaneous equations of all Rayleigh points: c ;

[0140] In addition, the projection of the sun direction vector on the optical compass coordinate system can also be expressed as:

[0141]

[0142] Among them, α s is the azimuth of the sun direction vector in the optical compass coordinate system, h s is the zenith angle of the sun direction vector in the optical compass coordinate system;

[0143] Then according to formula (20), we can find s c Then we can get the azimuth of the solar direction vector in the C system, that is:

[0144]

[0145] Among them, s c (1)s c (2) Divided into vector s c The first and second elements in ;

[0146] Finally, combine the time and solar ephemeris to obtain the azimuth of the solar direction vector in the n system The heading angle of the carrier can be obtained as:

[0147]

[0148]

[0149] or

[0150]

[0151] Among them, Ψ is the heading angle of the carrier, and π is the ambiguity of the polarization orientation.

[0152] In a specific implementation, the ambiguity π of the polarized light orientation can be removed by the quadrant position of the solar meridian projection or the heading angle difference between adjacent frames.

[0153] The polarized light orientation method based on Rayleigh point information in this embodiment is further described below with reference to specific examples.

[0154] Assume that there are M measurement points in the collected sky polarization image, and the measured polarization angles of these measurement points are:

[0155] P 1 =[φ 1 ,φ 2 ,…,φ M ] (26)

[0156] The theoretical polarization angle of each measurement point is:

[0157] P 2 =[φ 1 ',φ 2 ',…,φ M '] (27)

[0158] Then, the polarization angle errors of these measurement points are:

[0159] P 3 =[Δφ 1 ,Δφ 2 ,…,Δφ M ] (28)

[0160] When the horizontal attitude angle of the carrier is 0°, the measurement error of the polarization angle will be proportionally transferred to the heading angle estimation error. Then the orientation error ΔΨ caused by the polarization angle measurement error is error for:

[0161]

[0162] Formula (28) shows that the polarization angle error of each measurement point will affect the orientation error, and their weights are all 1 / M. If the polarization angle error of some measurement points is large, it will affect the final orientation accuracy.

[0163] Assume that the distance from the first measurement point to the m (m≤M) measurement points is the Rayleigh point that satisfies equation (19). In this case, only the Rayleigh point is used to complete the orientation error. for:

[0164]

[0165] Since the Rayleigh points used for orientation are all measurement points with small polarization angle errors, we have:

[0166]

[0167] Formula (31) shows that the error of orientation using only Rayleigh points is less than or equal to the error of orientation using all measurement points. In order to more intuitively illustrate that using only Rayleigh points for orientation solution can improve the orientation accuracy, let us assume an extreme case: from the first measurement point to the mth measurement point are Rayleigh points, and the polarization angle errors of these Rayleigh points are all a 1 , and the measurement points from the m+1th to the Mth are non-Rayleigh points, and the errors of these non-Rayleigh points are all a 2 , where a 1 and a 2 If we only consider the influence of polarization angle measurement error on orientation error, then the orientation error ΔΨ calculated using all measurement points is error for:

[0168]

[0169] Let the proportion of Rayleigh points to all measurement points be K 1 , the proportion of non-Rayleigh points to all measurement points is K 2 , then formula (32) can be rewritten as:

[0170] ΔΨ error =K 1 ·a 1 +K 2 ·a 2 (33)

[0171] Take a 1 =3°, a 2 =15°, the orientation error is:

[0172] ΔΨ error =3a 1 +15a 2 (34)

[0173] The schematic diagram of the effect of Rayleigh point ratio on orientation error is as follows Figure 3 As shown. Figure 3 It can be seen that the proportion of Rayleigh points will directly affect the orientation accuracy of polarized light. The higher the proportion of Rayleigh points, the smaller the orientation error, and the higher the proportion of non-Rayleigh points, the larger the orientation error.

[0174] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A polarized light orientation method based on Rayleigh point information, characterized in that: The steps include: Step 1, collecting a sky polarization image based on a polarization compass on a carrier, and calculating the measured polarization angle of each measurement point in the sky polarization image; Step 2, calculating the ideal polarization angle of each measurement point in the sky polarization image, and obtaining the polarization angle error of each measurement point based on the measured polarization angle and the ideal polarization angle; Step 3: Screen out Rayleigh points from all measurement points based on the polarization angle error, and perform polarization light orientation based on all Rayleigh points to obtain the heading angle of the carrier.

2. The polarized light orientation method based on Rayleigh point information according to claim 1, characterized in that: In step 1, the calculation process of the measured polarization angle is: The Stokes vector S0 contains four parameters S0 = [S1 S2 S3 S4], where S1 represents the total light intensity, S2 is the light intensity difference between 0° and 90°, S3 is the light intensity difference between 45° and 135°, and S4 is the circular polarization component. The intensity of polarized light after passing through the polarizer is: Where θ1 is the polarization angle, is the angle between the sensor polarization direction and the system optical axis; Omitting the S4 component, the simplified Stokes intensity equation is: When the polarization angle θ1 is 0°, 45°, and 90° respectively, the Stokes parameters of the measurement point are: Without considering circularly polarized light, the measured polarization angle at the measurement point is φ a =(1 / 2)·arctan(S3 / S2).

3. The polarized light orientation method based on Rayleigh point information according to claim 1, characterized in that: In step 2, the calculation process of the ideal polarization angle is: Calculate the projection v of the observation direction vector v of the measurement point on the optical compass coordinate system c ,for: v c =[sinγ v ·cosα v sinγ v ·sinα v -cosγ v ] T Among them, T is the transpose of the matrix, α v is the azimuth of the measuring point in the optical compass coordinate system, γ v is the zenith angle of the measuring point in the optical compass coordinate system; Calculate the projection s of the sun direction vector s on the optical compass coordinate system c ,for: in, is the transformation matrix from the carrier coordinate system to the optical compass coordinate system, is the transformation matrix from the navigation coordinate system to the optical compass coordinate system, s n is the sun direction vector in the navigation coordinate system; Based on the projection v of the observation direction vector v and the sun direction vector s on the optical compass coordinate system c 、s c , calculate the projection e of the E vector e of the measurement point on the optical compass coordinate system c ,for: yes c =k·v c ×s c Where k is a constant that makes both sides of the equation equal; The projection e of the E vector e of the measurement point on the optical compass coordinate system c Convert to the measurement point coordinate system: in, is the transformation matrix from the optical compass coordinate system to the measurement point coordinate system, e1, e2, e3 are vectors e v The three elements of In addition, the E vector e of the measuring point can also be expressed by the polarization angle in the measuring point coordinate system, which is: Therefore, the ideal polarization angle of the measurement point is φ b =arctan(e2 / e1).

4. The polarized light orientation method based on Rayleigh point information according to claim 2, characterized in that: The conversion matrix distance from the carrier coordinate system to the optical compass coordinate system is: The conversion matrix from the navigation coordinate system to the optical compass coordinate system is specifically: Among them, r0, θ0, Ψ0 are respectively provided by other sensors for the carrier roll angle, pitch angle and heading angle; The sun direction vector in the navigation coordinate system is specifically: in, is the azimuth of the sun direction vector in the navigation coordinate system, is the altitude angle of the sun direction vector in the navigation coordinate system.

5. The polarized light orientation method based on Rayleigh point information according to claim 2, characterized in that: The constant k that makes both sides of the equation equal is specifically: Where τ is the scattering angle.

6. The polarized light orientation method based on Rayleigh point information according to any one of claims 1 to 5, characterized in that: In step 2, the polarization angle error is specifically: Δφ=|φ a -f b | Among them, Δφ is the polarization angle error, φ a is the measured polarization angle, φ b is the ideal polarization angle.

7. The polarized light orientation method based on Rayleigh point information according to claim 6, characterized in that: In step 3, the process of screening out Rayleigh points among all measurement points based on the polarization angle error is as follows: For any measurement point, determine whether its polarization angle error satisfies Δφ≤φ thres If so, the measurement point is a Rayleigh point, otherwise it is a non-Rayleigh point, where φ thres is the threshold value.

8. The polarized light orientation method based on Rayleigh point information according to claim 7, characterized in that: The threshold φ thres =5°.

9. The polarized light orientation method based on Rayleigh point information according to any one of claims 1 to 5, characterized in that: In step 3, the process of polarization orientation based on all Rayleigh points is: Get the Rayleigh point set E consisting of all Rayleigh points c ,for: in, is the projection of the E vector of the ith Rayleigh point on the optical compass coordinate system, and L is the total number of Rayleigh points; Rayleigh point set E c Each Rayleigh point in satisfies the orthogonality of polarization vectors, that is: in, is the projection of the observation direction vector of the ith Rayleigh point on the optical compass coordinate system, s c is the projection of the sun direction vector on the optical compass coordinate system; At the same time and place, different Rayleigh points correspond to different E vectors and different observation direction vectors, but the corresponding sun direction vector is unified. Therefore, the projection s of the sun direction vector on the optical compass coordinate system can be obtained by using the Lagrange multiplier method to solve the simultaneous equations of all Rayleigh points. c ; In addition, the projection of the sun direction vector on the optical compass coordinate system can also be expressed as: Among them, α s is the azimuth of the sun direction vector in the optical compass coordinate system, h s is the zenith angle of the sun direction vector in the optical compass coordinate system; Right now: Among them, s c (1)s c (2) Divided into vector s c The first and second elements in ; Azimuth angle α based on the sun direction vector in the optical compass coordinate system s And the azimuth of the sun direction vector in the navigation coordinate system The heading angle of the carrier can be obtained as: or Among them, Ψ is the heading angle of the carrier, and π is the ambiguity of the polarization orientation.

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