CN104613956A - Atmospheric polarization neutral point-based navigation orientation method - Google Patents

Abstract

The invention discloses an atmospheric polarization neutral point-based navigation orientation method, which comprises the following steps: collecting an all-sky atmospheric polarization information graph; calculating the degree of polarization of the area collected in the step I; and calculating the orientation angle of the observation moment. According to the atmospheric polarization neutral point-based navigation orientation method, the defect that the errors of the photoelectric model polarization sensor are accumulated due to long-time navigation can be overcome, and the information on the obtained navigation angle is more reliable.

Description

Based on the navigation orientation method of atmospheric polarization neutral point

Technical field

The present invention relates to navigation field, be specially a kind of navigation orientation method based on atmospheric polarization neutral point.

Background technology

Sunshine in an atmosphere transmission can be subject to the scattering formation polarized light of atmospheric particles, and the polarized light of the aerial different polarization states in sky defines sky polarized light distribution pattern.In special time period, there is a metastable sky polarized light distribution pattern in the air in sky, follows certain regularity of distribution, contain abundant attitude information, can be used for navigation application.Atmospheric polarization airmanship, because it is based on atmospheric polarization type, has highly concealed type and is difficult to the features such as artificial interference, has become an important emerging direction of airmanship development.

Neutral point is one of important distribution feature of atmospheric polarization type, and be the sky polarization singular point formed because sunshine is subject to aerocolloidal depolarization effect, neutral point place degree of polarization is 0.Find at present, in atmospheric polarization type, co-exist in 4 neutral points, be i.e. Arago neutral point, Babinat neutral point, Btewster neutral point and the 4th neutral point.Neutral point on high in distribution there is obvious azimuth characteristic, but rarely have the navigation mark navigated as polarization by neutral point in prior art, thus provide the application of directional information accurately for independent navigation.

Summary of the invention

The object of the invention is to provide a kind of navigation orientation method based on atmospheric polarization neutral point to overcome above-mentioned deficiency.

The present invention is based on the navigation orientation method of atmospheric polarization neutral point, comprise the following steps:

The first step: the all-sky atmosphere polarization information figure of collection;

Second step: the degree of polarization of institute's pickup area in calculation procedure one;

3rd step: carry out image procossing to degree of polarization image, searches the region at neutral point place according to the size of degree of polarization, adopt the edge of ellipse fitting algorithm centering point region to carry out matching, this ellipse center location is measured atmospheric polarization neutral point;

4th step: two neutral points are carried out line, determines sun meridian direction;

5th step: calculate the forward angle of actual sun meridian to body axle;

6th step: calculate direct north to the meridianal forward angle of the sun;

7th step: the course angle in calculating observation moment.

The present invention is based on the navigation orientation method of atmospheric polarization neutral point, there is following beneficial effect:

The present invention is directed to the deficiency that existing polarotactic navigation directional technology exists, a kind of atmospheric polarization distribution pattern determination atmospheric polarization neutral point position based on whole day territory is proposed, neutral point is utilized to be distributed in principle on sun meridian, in conjunction with the method for two one lines, determine the meridianal position of the real sun, and then course angle information is provided, provide new method and thinking for utilizing atmospheric polarization light navigation orientation.The present invention is the essential characteristic from neutral point observation, the position of the atmospheric polarization type information determination central point of all-sky is obtained based on image procossing, all-sky atmospheric polarization acquisition device is utilized to obtain the polarization information of all-sky, when long-time navigation, sky polarization mode constantly changes, but the atmospheric polarization distribution pattern of all-sky is metastable, the polarization neutral point regularity of distribution is that all-the-time stable exists, thus guarantee the accuracy of the meridianal position of the sun, overcome photoelectricity model polarization sensor navigate for a long time time error accumulation shortcoming, the information of the course angle of trying to achieve is more reliable.

Accompanying drawing explanation

Fig. 1 is process flow diagram of the present invention;

Fig. 2 days aerial polarization neutral point ideal distribution schematic diagram;

Fig. 3 is sky, northeast geographic coordinate system schematic diagram;

Fig. 4 is that neutral point asks for carrier heading Space figure;

Fig. 5 is plane figure;

Embodiment

The present invention is further illustrated below in conjunction with drawings and Examples.

Embodiment: the navigation orientation method based on atmospheric polarization neutral point of the present invention comprises the following steps: the first step: the all-sky atmosphere polarization information figure of collection; Second step: the degree of polarization of institute's pickup area in calculation procedure one; 3rd step: carry out image procossing to degree of polarization image, searches the region at neutral point place according to the size of degree of polarization, adopt the edge of ellipse fitting algorithm centering point region to carry out matching, this ellipse center location is measured atmospheric polarization neutral point; 4th step: two neutral points are carried out line, determines sun meridian direction; 5th step: calculate the forward angle of actual sun meridian to body axle; 6th step: calculate direct north to the meridianal forward angle of the sun; 7th step: the course angle in calculating observation moment.

Under single scattering condition, sky polarisation of light be generally on the occasion of, sunshine is under Multiple Scattering condition, and atmospheric particles can cause negative bias to shake.The sky degree of polarization of positive and negative polarization cross place is zero, i.e. atmospheric polarization neutral point.Neutral point is one of important distribution feature of atmospheric polarization type, and the degree of polarization of this point is minimum and size is 0.Along with the change of time, the sun on high in position constantly change, the degree of polarization of sky regional area and polarization azimuth are also in continuous change, but polarization neutral point is distributed in the sun, and meridianal characteristic can not change, as shown in Figure 2, neutral point is positioned at the principal plane of the sun and zenith, namely neutral point is distributed on sun meridian, any moment takes all-sky, it is aerial all minimumly observes two neutral points, according to these character of neutral point, we can by neutral point on high in position, according to the mathematical principle of " determining straight line at 2 ", the meridianal orientation of the reverse sun.

As long as determine neutral point on high in orientation.Can determine to observe the meridianal position of the moment sun.Then the forward angle of sun meridian to body axle can be tried to achieve, and solar azimuth and direct north can be drawn by uranology computing formula by the longitude and latitude in the geographic position observing moment and observation to the meridianal angle of the sun, with sun meridian for standard, the forward angle of direct north to observer's body axle can be calculated, namely required course angle information, specifically ask calculation process as follows:

As shown in Figure 3, set up sky, northeast coordinate system, namely with the position at ground observation person place for initial point O, with geographical direct north for X-axis, with direction, geographical due east for Y-axis, to cross the vertical line of zenith for Z axis.Being that radius is sphere W with r, is s by the intersection point of the observation moment sun and observer position O point line and sphere W, and the line between definition s point and initial point O and the angle of XOY plane are the elevation angle θ of the sun _s, elevation angle θ _sspan be [0 °, 90 °], the angle of the projection in XOY plane of definition s point and the line of initial point O and X-axis is the position angle of the sun position angle span be [0 °, 360 °], setting the angle be between two straight lines crossing initial point in plane X OY is that the value of described forward angle is not more than 360 ° with the clockwise direction of looking along Z-axis direction O point from zenith as forward angle; Navigation direction with observer towards (body axle) characterize, geographical direct north to observer towards the forward angle of (body axle) be observer position angle.Sun altitude and position angle can be tried to achieve according to uranology computing formula:

sinθ _s＝sinδ·sin Lon+cosδ·cos Lon·cos T (1)

θ in above formula _sfor sun altitude, for solar azimuth, Lon is observer place geographic latitude, and δ is the declination angle of the sun, and T is local solar hour angle.

In Fig. 3, the camber line connecting Z point and S point is sun meridian, and we can determine the forward angle of sun meridian and geographical direct north to observe the geographic position of moment and observer by formula (2) utilization if the forward angle α of sun meridian to observer's body axle can be tried to achieve _s, just can try to achieve the angle of geographical direct north to observer's body axle namely the course angle in moment is observed.

Under different polarization angles, use CCD camera, fish eye lens, linear polarizer and the optical filter atmosphere polarization information to all-sky to sample, polarization angle β is respectively 0 °, 60 ° and 120 °, and the all-sky atmosphere polarization information figure of corresponding collection is K ₁, K ₂and K ₃, gathered image is processed, utilizes the intensity signal of image to calculate corresponding Stokes vector S=(I, Q, U) ^t, corresponding computing formula is as follows:

$\left\{\begin{array}{c}I+Q\cos 2{\mathrm{\β}}_1+U\sin 2{\mathrm{\β}}_1=2I_1\\ I+Q\cos 2{\mathrm{\β}}_2+U\sin 2{\mathrm{\β}}_2=2I_2\\ I+Q\cos 2{\mathrm{\β}}_3+U\sin 2{\mathrm{\β}}_3=2I_3\end{array}\right.---\left(3\right)$

In formula (3), I is total light intensity of polarized light, and Q is the polarized light component in horizontal direction, and U is 45 ° of direction linear polarization light components, β _n(n≤3, n is natural number) are polarization angle, and value is respectively 0 °, 60 ° and 120 °, I _n(n≤3, n is natural number) are for gathering the intensity signal of image.

According to above-mentioned stokes vector S=(I, Q, U) ^tthrough type (4) can try to achieve the degree of polarization P of institute's pickup area and the distribution of polarization azimuth ψ

$\left\{\begin{array}{c}P=\frac{\sqrt{Q^2+U^2}}{I}\\ \mathrm{\ψ}=\frac{1}{2}\arctan \left(\frac{U}{Q}\right)\end{array}\right.---\left(4\right)$

In formula (4), I is total light intensity of polarized light, and Q is the polarized light component in horizontal direction, and U is 45 ° of direction linear polarization light components.

After the atmospheric polarization position angle obtaining all-sky and degree of polarization, degree of polarization size is mapped as degree of polarization distributed image, and the large I of each point degree of polarization is obtained by formula (4).

Atmospheric polarization neutral point has following distribution characteristics: it is aerial, and the degree of polarization of this point is minimum and size is 0; In polarization angle distribution pattern, along being parallel to sun meridian or this position of process, the anti-sun meridianal direction, the direction of polarization angle will rotate, and change the sign symbol of polarization angle value.

Image procossing is carried out to degree of polarization image, the region at neutral point place is searched according to the size of degree of polarization, the edge of ellipse fitting algorithm centering point region is adopted to carry out matching, this ellipse center location is measured atmospheric polarization neutral point, according to the character of atmospheric polarization neutral point, it is parallel with observation moment sun meridian that two neutral points carry out line, then in image, the line L of two elliptical center is the sun meridian in observation moment.

Fig. 4 is fundamental diagram of the present invention, the placement location of fixing collecting device and carrier, make proper axle T and the middle line parallel of image collected, in conjunction with the line L of the polarization neutral point that polarization image is tried to achieve, i.e. sun meridian, can determine that in image, L is to the forward angle α of body axle, as shown in Figure 5 owing to there is sun meridian and inverse sun meridian, so there is the direction fuzzy problem of 180 ° in forward angle α, realization rate of the present invention is for take pictures to all-sky, picture centre is shooting moment zenith position, therefore can according to the intensity signal determination sun in image on high in position, can distinguish according to the position relationship of the position of sun in image and image center line.Actual sun meridian is to the forward angle α of body axle _scan by following condition criterion:

If in image, the position of the sun is positioned at the left side of image center line, then α _s=α

If in image, the position of the sun is positioned at the right side of image center line, then α _s=360 ° of-α

α in above formula _sfor actual sun meridian is to the forward angle of body axle, α be in image L to the forward angle of body axle.

The forward included angle of observation moment geographical direct north to carrier body axle can be obtained according to formula (5) ₀

α in formula (5) _sfor observation moment actual sun meridian is to the forward angle of body axle, for the direct north of trying to achieve according to the longitude and latitude inquiry solar calendar in observation moment and observation is to the meridianal forward angle of the sun.

Above-described embodiment is the present invention's preferably embodiment; but embodiments of the present invention are not restricted to the described embodiments; change, the modification done under other any does not deviate from Spirit Essence of the present invention and principle, substitute, combine, simplify; all should be the substitute mode of equivalence, be included within protection scope of the present invention.

Claims (7)

1., based on a navigation orientation method for atmospheric polarization neutral point, it is characterized in that comprising the following steps:

The first step: the all-sky atmosphere polarization information figure of collection;

Second step: the degree of polarization of institute's pickup area in calculation procedure one;

3rd step: carry out image procossing to degree of polarization image, searches the region at neutral point place according to the size of degree of polarization, adopt the edge of ellipse fitting algorithm centering point region to carry out matching, this ellipse center location is measured atmospheric polarization neutral point;

4th step: two neutral points are carried out line, determines sun meridian direction;

5th step: calculate the forward angle of actual sun meridian to body axle;

6th step: calculate direct north to the meridianal forward angle of the sun;

7th step: the course angle in calculating observation moment.

2. the navigation orientation method based on atmospheric polarization neutral point according to claim 1, it is characterized in that in the described first step, under different polarization angles, use CCD camera, fish eye lens, linear polarizer and the optical filter atmosphere polarization information to all-sky to sample, polarization angle β is respectively 0 °, 60 ° and 120 °, and the all-sky atmosphere polarization information figure of corresponding collection is K ₁, K ₂and K ₃.

3. the navigation orientation method based on atmospheric polarization neutral point according to claim 1 and 2, it is characterized in that, in described second step, processing gathered image, utilize the intensity signal of image to calculate corresponding Stokes vector S=(I, Q, U) ^t, computing formula is as follows:

$\left\{\begin{array}{c}I+Q\cos {2\mathrm{\β}}_1+U\sin {2\mathrm{\β}}_1={2I}_1\\ I+Q\cos {2\mathrm{\β}}_2+U\sin {2\mathrm{\β}}_2={2I}_2\\ I+Q\cos {2\mathrm{\β}}_3+U\sin {2\mathrm{\β}}_3={2I}_3\end{array}\right.---\left(3\right)$

In formula (3), I is total light intensity of polarized light, and Q is the polarized light component in horizontal direction, and U is 45 ° of direction linear polarization light components, β _n(n≤3, n is natural number) are polarization angle, and value is respectively 0 °, 60 ° and 120 °, I _n(n≤3, n is natural number) are for gathering the intensity signal of image.

According to above-mentioned stokes vector S=(I, Q, U) ^tthe degree of polarization P of institute's pickup area and the distribution of polarization azimuth ψ is tried to achieve by formula (4) below

$\left\{\begin{array}{c}P=\frac{\sqrt{Q^2+U^2}}{I}\\ \mathrm{\ψ}=\frac{1}{2}\arctan \left(\frac{U}{Q}\right)\end{array}\right.---\left(4\right)$

In formula (4), I is total light intensity of polarized light, and Q is the polarized light component in horizontal direction, and U is 45 ° of direction linear polarization light components.

4. the navigation orientation method based on atmospheric polarization neutral point according to claim 1 and 2, it is characterized in that: in described 3rd step and the 4th step, image procossing is carried out to degree of polarization image, the region at neutral point place is searched according to the size of degree of polarization, the edge of ellipse fitting algorithm centering point region is adopted to carry out matching, this ellipse center location is measured atmospheric polarization neutral point, according to the character of atmospheric polarization neutral point, it is parallel with observation moment sun meridian that two neutral points carry out line, then in image, the line L of two elliptical center is the sun meridian in observation moment.

5. the navigation orientation method based on atmospheric polarization neutral point according to claim 1 and 2, is characterized in that: in described 5th step, if the position of the sun is positioned at the left side of image center line in image, then α _s=α;

If in image, the position of the sun is positioned at the right side of image center line, then α _s=360 ° of-α; Wherein α _sfor actual sun meridian is to the forward angle of body axle, α be in image L to the forward angle of body axle.

6. the navigation orientation method based on atmospheric polarization neutral point according to claim 1 and 2, is characterized in that: in described 6th step, utilize below formulae discovery direct north to the meridianal forward angle of the sun,

sinθ _s＝sinδisinLon+cosδicosLonicosT (1)

Wherein middle θ _sfor sun altitude, for solar azimuth, Lon is observer place geographic latitude, and δ is the declination angle of the sun, and T is local solar hour angle.

7. the navigation orientation method based on atmospheric polarization neutral point according to claim 1 and 2, is characterized in that: in described 7th step, can obtain the forward included angle of observation moment geographical direct north to carrier body axle according to formula (5) ₀, namely observe the course angle in moment,

α in formula (5) _sfor observation moment actual sun meridian is to the forward angle of body axle, for the direct north of trying to achieve according to the longitude and latitude inquiry solar calendar in observation moment and observation is to the meridianal forward angle of the sun.