Solar tracking and integrated navigation method and device based on polarized light rotation field

Abstract

The invention discloses a sun tracking and integrated navigation method and device based on a polarized light rotation field, and belongs to the field of autonomous navigation. Firstly, a polarization degree image and a polarization angle image are collected; gradient change information is extracted by adopting a variable step gradient fusion method; further calculating to obtain a polarization E vector, a polarization degree gradient and a polarization E vector rotation, and estimating the maximum polarization degree by adopting a regional point set density fusion method based on statistical distribution characteristics; and establishing a polarized light rotation field according to the information, and constructing a sun tracking model and an integrated navigation measurement model based on the polarized light rotation field for realizing sun tracking or correcting a sky direction misalignment angle of integrated navigation. According to the method, spatial neighborhood constraint information contained in a polarized light field is mined, the vertical under-constraint problem of a traditional polarization navigation method based on a polarization E vector or a polarization degree gradient vector is solved, and a new solution is provided for improving polarization navigation robustness.

Description

Technical Field

[0001] The present invention belongs to the field of autonomous navigation, and particularly relates to a solar tracking and integrated navigation method and device based on the polarization rotation field of polarized light. Background Art

[0002] Navigation, as a perception method for measuring and estimating physical motion information such as the attitude, speed, and position of a moving object, is a key technology for unmanned systems in autonomy and intelligence. Among the existing main navigation methods, the inertial navigation system has long-term error accumulation and decreasing accuracy; the vision navigation system is limited to structured environments and restricted spaces, and it is difficult to meet the urgent needs of cross-domain long-term autonomous navigation; the satellite / inertial integrated navigation system is vulnerable to means such as satellite denial and communication interference. Therefore, there is an urgent need to explore a highly reliable, strongly robust, and fully autonomous method for perceiving spatial motion information to ensure the task execution of unmanned systems in a denied environment.

[0003] Compound eyes of organisms such as insects, migratory birds, and mantis shrimp can perceive the polarized light field formed by the scattering of the sun through the atmosphere for determining their own headings. The developed bionic polarization navigation has advantages such as full autonomy and no error accumulation, and has now become an emerging and interdisciplinary technical direction. Bionic polarization navigation mainly calculates the solar vector through polarization characteristic information such as the degree of polarization and the polarization E vector, and then constructs the measurement constraint relationship between it and the navigation information. However, the existing polarization navigation methods still have deficiencies in terms of robustness, specifically reflected in the aspects of lack of information and underdetermined constraints.

[0004] In terms of the lack of information, CN113819907A (an inertial / polarization navigation method based on polarization and solar double-vector switching) discloses that measurement fusion decision is carried out based on multi-sensor independent observation of polarization information in different directions to achieve integrated navigation. CN117308926A (a solar vector optimization method based on a sun sensor and a polarization sensor) discloses that measurement fusion decision based on a polarization compound eye sensor and a sun sensor is used to achieve integrated navigation. The above methods only utilize the single polarization E-vector feature distribution information, and the polarization degree information is only used as a weighting factor to characterize the measurement quality, ignoring the polarization navigation features contained in the polarization degree distribution. CN118464020A (a combined navigation method based on underwater polarization degree gradient measurement) discloses that only relying on the polarization degree information to correct the celestial misalignment angle of underwater integrated navigation. Due to the instability of the single polarization degree distribution feature and the lack of introduction of more stable polarization E-vector feature distribution information, the robustness of this method is weak under environmental noise interference; in terms of information correlation, the above methods regard the measurement information in different observation directions as independent, only considering the vertical constraints formed by each measurement and the solar vector respectively, without analyzing the correlation constraints between the measurement information implied in the local area change, resulting in the solar vector being only constrained in a vertical plane in the local area, with an underdetermined problem, increasing the uncertainty of the solar vector solution, and thus affecting the polarization navigation accuracy.

[0005] In summary, the lack of information and underdetermined constraints existing in the existing polarization navigation will lead to a reduction in robustness. In terms of the lack of information, it is necessary to integrate the constraint characteristics contained in multi-dimensional polarization features such as polarization E-vector and polarization degree to enhance the information utilization ability; in terms of underdetermined constraints, it is necessary to analyze the correlation constraints of the measurement information from the local area change characteristics to overcome the underdetermined problem caused by the traditional vertical constraint between the measurement and the solar vector. Summary of the Invention

[0006] To solve the above technical problems, the present invention proposes a solar tracking and integrated navigation method based on the polarization light vorticity field, which simultaneously considers the vorticity distribution characteristics and navigation constraints of the spatial polarization light field including polarization degree and polarization E-vector distribution. By introducing the local observation area change characteristics of the polarization light field, a collinear constraint between the polarization information and the solar vector can be established, overcoming the vertical underdetermined constraint defect existing in the traditional polarization navigation method, and introducing the polarization E-vector information to enhance the stability of the constraint based on the polarization degree information alone, providing a new solution for improving the robustness of bionic polarization navigation.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A solar tracking and integrated navigation method based on the polarization light vorticity field, comprising the following steps:

[0009] Step 1: Calculate the degree of polarization image and the polarization angle image based on the intensity images with polarization analysis directions of 0°, 45°, 90°, and 135° collected by the polarization image sensor ;

[0010] Step 2: Adopt the variable step - size gradient fusion method to extract the gradient change information of the degree of polarization image and the polarization angle image in the X - direction and Y - direction ;

[0011] Step 3: Calculate the polarization E - vector , the degree of polarization gradient and the curl of the polarization E - vector according to the degree of polarization image , the polarization angle image and their gradient change information , , , , and estimate the maximum degree of polarization using the regional point - set density fusion method based on statistical distribution characteristics;

[0012] Step 4: Calculate the polarization light curl field according to the result of Step 3, and construct a solar tracking model and a combined navigation measurement model .

[0013] A solar tracking and combined navigation device based on the polarization light curl field includes the following modules:

[0014] Degree of polarization image and polarization angle image calculation module: Calculate the degree of polarization image and the polarization angle image based on the intensity images with polarization analysis directions of 0°, 45°, 90°, and 135° collected by the polarization image sensor ;

[0015] Gradient change information extraction module: Adopt the variable step - size gradient fusion method to extract the gradient change information of the degree of polarization image and the polarization angle image in the X - direction and Y - direction ;

[0016] Maximum degree of polarization estimation module: According to the degree of polarization image , the polarization angle image and their gradient change information , , , The calculated polarization E vector , the polarization degree gradient and the curl of the polarization E vector are obtained, and a method for estimating the maximum polarization degree by fusing the density of regional point sets based on statistical distribution characteristics is adopted ;

[0017] A model construction module calculates the curl field of polarized light according to the result of step 3 , and constructs a solar tracking model and a combined navigation measurement model .

[0018] An electronic device includes: one or more processors; a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned solar tracking and combined navigation method based on the curl field of polarized light.

[0019] A computer-readable storage medium stores executable instructions thereon, and when the instructions are executed by a processor, the processor implements the above-mentioned solar tracking and combined navigation method based on the curl field of polarized light.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention constructs a spatial polarized light curl field by extracting the gradient change information of the polarization image, comprehensively utilizes the spatial neighborhood change constraints of multi-dimensional polarization feature information including polarization degree and polarization E vector, and overcomes the information deficiency problem existing in the traditional polarization navigation method based on a single polarization feature; considering the influence of polarization imaging noise, a variable step-size gradient fusion method and a method for fusing the density of regional point sets based on statistical distribution characteristics are designed to enhance the robustness of gradient information extraction and maximum polarization degree estimation; a solar tracking model and combined navigation measurement constraints based on the curl field of polarized light are designed, and the collinear constraint between the curl field of polarized light and the solar vector overcomes the vertical under-constraint problem existing in the traditional polarization navigation method, improves the solar tracking accuracy and robustness, and enhances the error correction ability of combined navigation. Description of the Drawings

[0022] Figure 1 is a flowchart of a solar tracking and combined navigation method based on the curl field of polarized light according to the present invention;

[0023] Figure 2 is a schematic diagram of the calculation result of the curl field of polarized light according to the present invention;

[0024] Figure 3 is a comparison chart of the solar tracking performance between the embodiment of the present invention and the traditional method based on the polarization degree gradient;

[0025] Figure 4 This is a comparison chart of the results of the heading angle and the celestial misalignment angle between the embodiment of the present invention and the traditional combined navigation method based on the polarization degree gradient. Detailed implementation manners

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, the present invention adopts the following technical solutions.

[0027] According to an embodiment of the present invention, as Figure 1 shown, a solar tracking and integrated navigation method based on the polarization light vorticity field of the present invention includes the following steps:

[0028] Step 1: Calculate the polarization degree image and the polarization angle image based on the intensity images with the polarization analysis directions of 0°, 45°, 90°, and 135° collected by the polarization image sensor ;

[0029] ;

[0030] Step 2: Adopt the variable step size gradient fusion method to extract the gradient change information of the polarization degree image and the polarization angle image in the X direction and the Y direction respectively;

[0031] Based on the polarization degree image and the polarization angle image calculated in Step 1, adopt the variable step size gradient fusion method to extract the gradient change information in their X direction and Y direction;

[0032] ;

[0033] Among them, is the element-wise product operator, is the convolution operator, , are the X-direction convolution kernel and its weight, , are the Y-direction convolution kernel and its weight value.

[0034] When the step size takes , the X-direction convolution kernel and its weight and the convolution kernel in the Y direction and its weights are respectively

[0035] ;

[0036] Step 3: According to the polarization degree image , the polarization angle image and its gradient change information , , , calculate the polarization E vector , the polarization degree gradient and the curl of the polarization E vector , and estimate the maximum polarization degree by using the regional point set density fusion method based on statistical distribution characteristics ;

[0037] First, according to the polarization degree image , the polarization angle image and its gradient change information , , , calculate the polarization E vector , the polarization degree gradient and the curl of the polarization E vector :

[0038] ;

[0039] ;

[0040] wherein , is the camera focal length, are respectively the X - direction and Y - direction coordinates of the polarization degree or polarization angle image. is the value of the polarization angle image , , are respectively and values, , are respectively and values, is the Nabla operator;

[0041] Furthermore, according to the polarization degree image and the polarization degree gradient , estimate the maximum polarization degree by using the candidate region density weighted fusion method based on statistical distribution characteristics :

[0042] ;

[0043] Among them, is the summation operator, is the conditional AND operator, is the vector modulus operator, is the corresponding quantile. is the point set density weight, is the all-ones matrix, is the maximum polarization degree band feature matrix.

[0044] Step 4. Calculate the polarization light curl field and construct the solar tracking model and the integrated navigation measurement model ;

[0045] Based on the polarization E vector , polarization degree gradient , polarization E vector curl and maximum polarization degree calculated in Step 3, calculate the polarization light curl field , construct the solar tracking model to track the solar vector . The solar tracking model is expressed as follows:

[0046] ;

[0047] Among them, is the skew-symmetric matrix operator, is the th polarization light curl measurement, is the number of polarization light curl measurements, is the value of the polarization degree image , radial gradient , and take ;

[0048] Based on the polarization light curl field , the integrated navigation measurement model can be constructed:

[0049] ;

[0050] Among them, is the solar vector in the navigation system , is the strapdown attitude matrix, is the strapdown attitude matrix with errors as the carrier system for measuring the rotation amount of polarized light is the attitude misalignment angle is the measurement noise

[0051] Embodiment:

[0052] This embodiment takes a polarized image sensor based on the pinhole camera model as an example for simulation, and the simulation algorithm parameters are shown in Table 1

[0053] Table 1

[0054] For the variables in the subsequent formulas of this embodiment, their definitions and calculation formulas are the same as those of the variables in the specification, and will not be elaborated here. The specific steps are as follows

[0055] The first step: Define the parameters of the polarized image sensor according to the image size, image center, and camera focal length in Table 1, and simulate the degree of polarization image and the polarization angle image ;

[0056] The second step: Adopt the variable-step gradient fusion method, and calculate the convolution kernel in the X direction of the image and its weight and the convolution kernel in the Y direction and its weight value according to the step size defined in Table 1 . According to the calculated convolution kernels and weights, extract the gradient change information of the degree of polarization image and the polarization angle image in the X direction and Y direction

[0057] The third step: According to the degree of polarization image , the polarization angle image and their gradient change information , , , calculate the polarized E vector , the degree of polarization gradient and the curl of the polarized E vector .

[0058] According to the degree of polarization image and the degree of polarization gradient calculate the maximum degree of polarization band feature matrix , take the dimension of the all-1 matrix in Table 1 as a parameter, and further calculate the point set density weight , combined with the degree of polarization image Weighted fusion estimation of maximum degree of polarization ;

[0059] Step 4: According to the polarization E vector calculated in the third step , degree of polarization gradient , curl of polarization E vector and maximum degree of polarization , construct the curl field of polarized light , adopt the method based on singular value decomposition to solve the solar tracking model , obtain the solution of the homogeneous equation, that is, the solar vector , to achieve solar tracking. According to the curl field of polarized light , a combined navigation measurement model can be constructed . Combining with the traditional fifteen-dimensional inertial navigation error state equation, the Kalman filtering algorithm can be used to correct the misalignment angle in the celestial direction and improve the orientation accuracy of the combined navigation.

[0060] Based on the parameters in Table 1, the curl field of polarized light when the solar zenith angle is 45° obtained by the processing of this embodiment is as Figure 2 shown, where the solid arrow is the curl field of polarized light , which can express the collinear constraint with the solar vector, and the dotted arrow is the traditional polarization E vector , which only expresses the perpendicular constraint with the solar vector. Therefore, for the underdetermined constraint problem, the collinear constraint of the method of the present invention is stronger than the perpendicular constraint of the traditional polarization E vector .

[0061] To verify the improvement effect of the solar tracking performance of the present invention compared with the traditional method based on the degree of polarization gradient, using simulation software, at intervals of 5°, in the range of solar azimuth from 0° to 360° and solar zenith angle from 0° to 90°, multiple simulation verifications are carried out, where the degree of polarization image and polarization angle image are both added with Gaussian noise, and the noise standard deviation is shown in Table 1, and the step size is taken as 75. As Figure 3 shown, the root mean square error of estimating the solar position using the method in this embodiment is 0.56°, and the traditional method based on the degree of polarization gradient is susceptible to noise, and the root mean square error of the obtained estimated solar position is 2.75°. Therefore, for the problem of lack of information, the method of the present invention is less affected by sampling noise compared with the traditional method based on the degree of polarization gradient, and has strong robustness in solar tracking by using the spatial neighborhood change information.

[0062] To verify the correction effect of the misalignment angle in the celestial direction of the combined navigation of the present invention compared with the traditional method based on the degree of polarization gradient, a motion trajectory is generated using simulation software, and the error parameters of the inertial navigation device are shown in Table 1. Figure 4 of (a), Figure 4In (b), the heading angle curve and the celestial misalignment angle curve obtained by using the classical Kalman filter for integrated navigation filtering are shown. The root mean square error of correcting the celestial misalignment angle using the method in this embodiment is 10.81', and the root mean square error of correcting the celestial misalignment angle using the traditional polarization degree gradient-based method is 11.03'. Therefore, in terms of correcting the integrated navigation celestial misalignment angle, the method of the present invention has higher accuracy than the traditional polarization degree gradient-based method.

[0063] Although the above description of the illustrative specific embodiments of the present invention is provided for the understanding of those skilled in the art in this technical field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in this technical field, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

Claims

1. A solar tracking and integrated navigation method based on the polarization light vorticity field, characterized in that It includes the following steps: Step 1: Calculate the degree of polarization image and the polarization angle image based on the intensity images with polarization analysis directions of 0°, 45°, 90°, and 135° collected by the polarization image sensor ; Step 2: Use the variable step-size gradient fusion method to extract the degree of polarization image and the polarization angle image The gradient change information in the X and Y directions ; Step 3: According to the polarization degree image , the polarization angle image and its gradient change information , , , calculate the polarization E vector , the polarization degree gradient and the curl of the polarization E vector , and use the regional point set density fusion method based on statistical distribution characteristics to estimate the maximum polarization degree ; Step 4: Calculate the polarization light curl field based on the result of Step 3 and construct a solar tracking model as well as a combined navigation measurement model .

2. The solar tracking and integrated navigation method based on the polarization light vorticity field according to claim 1, wherein The step 2 includes: Degree of polarization image calculated according to Step 1 and the polarization angle image , using a variable step-size gradient fusion method, extract the gradient change information in the X and Y directions ; ； Among them, is an element-wise multiplication operator, is a convolution operator, and are the convolution kernel and its weight in the X direction, and are the convolution kernel and its weight in the Y direction.

3. A solar tracking and integrated navigation method based on the polarization light vorticity field according to claim 2, characterized in that The said step 2 further includes: when the step size takes the X-direction convolution kernel of the polarization degree or polarization angle image and its weight and the Y-direction convolution kernel and its weight value are: 。 4. A solar tracking and integrated navigation method based on the polarization light vorticity field according to claim 3, characterized in that, The step 3 includes: Degree of polarization image calculated according to Step 1 and Step 2 , degree of polarization angle image and its gradient change information , , , The polarization E vector is calculated , degree of polarization gradient and curl of the polarization E vector : ； ； Among them, , is the camera focal length, are the X-direction and Y-direction coordinates of the degree of polarization or polarization angle image respectively, is the polarization angle image value, , are respectively and values, , are respectively and values, is the Nabla operator.

5. A solar tracking and integrated navigation method based on the polarization light vorticity field according to claim 4, characterized in that, The said step 3 further includes: according to the polarization degree image and the polarization degree gradient , using a candidate region density weighted fusion method based on statistical distribution characteristics to estimate the maximum polarization degree : ； Among them, is a summation operator, is a conditional AND operator, is a vector modulus operator, corresponds to quantile, is the point set density weight, is a matrix of all 1s, is the maximum degree of polarization band feature matrix.

6. A solar tracking and integrated navigation method based on the polarization light vorticity field according to claim 5, wherein The step 4 includes: The polarized E vector calculated according to step 3 , the polarization degree gradient , the curl of the polarized E vector and the maximum polarization degree , calculate the curl field of polarized light , construct a solar tracking model to achieve tracking of the solar vector , the solar tracking model is expressed as follows: ； Among them, is an anti-symmetric matrix operator, is the th polarization light rotation measurement, is the number of polarization light rotation measurements, is the value of the degree of polarization image , the radial gradient , and take .

7. A solar tracking and integrated navigation method based on the polarization light vorticity field according to claim 6, characterized in that, The step 4 further includes: Based on the polarization light curl field , a combined navigation measurement model is constructed : ； Among them, is the solar vector in the navigation system , is the attitude matrix of strapdown solution is the attitude matrix of strapdown solution with errors is the vehicle body coordinate system is the measurement of the polarization light rotation amount is the attitude misalignment angle is the measurement noise 8. A solar tracking and integrated navigation device based on the polarization light vorticity field, characterized in that, It includes the following modules: Degree of polarization image and polarization angle image calculation module, based on the intensity images with analyzer directions of 0°, 45°, 90°, and 135° respectively collected by the polarization image sensor , calculate the degree of polarization image and the polarization angle image ; Gradient change information extraction module, using a variable step-size gradient fusion method, extracts the degree of polarization image and the polarization angle image gradient change information in the X and Y directions ; The maximum polarization degree estimation module, based on the polarization degree image , the polarization angle image and its gradient change information , , , to calculate the polarization E vector , the polarization degree gradient and the curl of the polarization E vector , and use the regional point set density fusion method based on statistical distribution characteristics to estimate the maximum polarization degree ; The model construction module calculates the polarization light curl field according to the result of step 3 , and constructs a solar tracking model and a combined navigation measurement model .

9. An electronic device, characterized in that, It includes: One or more processors; A memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the method for solar tracking and integrated navigation based on the polarization light rotation field according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores executable instructions thereon, and when the instructions are executed by a processor, the processor implements the method for solar tracking and integrated navigation based on the polarization light rotation field according to any one of claims 1 to 7.

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