CN104776845A - Autonomous star recognition method based on combination mode - Google Patents

Abstract

The invention discloses an autonomous star recognition method based on a combination mode. The feature of a combined main star in the combined mode of a radial mode and an encoding mode is adopted as the feature vector of the main star. In the recognition process, the search range of the main star in a navigation star feature library is reduced through an encoded value corresponding to the main star, the feature vector of the main star is matched and compared with vectors in the navigation star feature library, and autonomous recognition of the star is completed. The combination mode of the main star has horizontal movement and rotation invariance, and the high recognition rate is achieved, so that the method is more suitable for autonomous recognition of the star. Meanwhile, high star recognition speed is achieved, and the sensitivity of a system can be improved.

Description

A kind of based on integrated mode from primary recognition methods

Technical field

The invention belongs to field of navigation technology, particularly relate to a kind of based on integrated mode from primary recognition methods.

Background technology

In celestial navigation location, to location and the identification of the aerial fixed star in sky, effectively can determine the directional information of aircraft; Consider based on scientific research and hardware cost aspect, autonomous star tracker is regarded as the first-selection of attitude measurement equipment on most of aircraft; An autonomous star tracker can automatically carry out the identification of star and resolving of attitude of flight vehicle; Star accuracy of identification directly affects the precision that attitude of flight vehicle resolves.Therefore, in star sensor, effective, accurate star recognizer is very crucial.

In the past few decades, many scholars are devoted to the research of star recognizer, are widely used in attitude algorithm and the control of aircraft based on the star tracker on this basis; Star recognizer can be divided into two base class: Subgraph Isomorphism and pattern-recognition; In these algorithms, do not utilize the prior imformation of any relevant flight device attitude; In first classification, asterism is as the summit of figure, use the plan range between star pair, or the plan range (also may comprise the monochrome information of asterism) between three stars is as the feature of star identification, and this kind of algorithm mainly comprises triangle algorithm, polygon algorithm and group matching algorithm etc.; And in the algorithm of Equations of The Second Kind, use some the observation star in visual field or all observe star build the pattern being easy to define, it represents algorithm trellis algorithm, neural network algorithm and genetic algorithm.

In recent years, due to the development of pattern-recognition, it is widely used in star identification.The people such as Zhang Guangjun propose based on the radial direction of star pattern and the whole day of cycle specificity from primary recognizer, and this algorithm, compared with trellis algorithm, has more sane recognition performance.In this algorithm, radial mode has reliable invariable rotary feature.But this algorithm depends on the size of storage space and the expense of recognition time to obtain better performance; Meanwhile, cycle specificity is to position noise-sensitive, and in order to reduce the complexity of star recognizer and accelerate the speed of star identification, Youngwoo Yoon proposes the thought of coding mode, pattern matching problem is reduced to the comparison between round values.But this algorithm needs to choose a suitable adjacent star to build the standard shaft of star pattern.And the probability choosing suitable adjacent star is often lower, therefore, will the standard shaft of generation error if having chosen inappropriate adjacent star, thus cause star identification unsuccessful.In addition, other scholar proposes different star recognizers on the basis of pattern-recognition.

In star sensor, require the identification realizing star as far as possible fast and reliably, thus be that follow-up process improves identifying information more accurately.Along with the development of survey of deep space, more and more higher to the requirement of star recognizer.Therefore set up star recognizer that is quick, accurate, robust to have great importance.

Summary of the invention

The object of the present invention is to provide a kind of based on integrated mode from primary recognition methods, be intended to solve existing star recognizer discrimination low, the problem that recognition speed is slow.

The present invention realizes like this, a kind of based on integrated mode from primary recognition methods, from primary recognition methods, the contiguous range of primary should be divided into equally spaced endless belt from inside to outside based on integrated mode, the mean level of the sea of primary and the adjacent star on each endless belt is apart from forming the feature of primary under radial mode; The number of adjacent star on each endless belt, the encoded radio utilizing code base to obtain is the feature of primary under coding mode; The structural feature primary proper vector in the combined mode of combination primary under radial mode and coding mode; The optical axis of CCD is pointed to one by one the nautical star in fundamental catalog, generate the proper vector corresponding to nautical star, and save as the form of database, form the feature database of nautical star; The encoded radio corresponding to primary is utilized to reduce the hunting zone in nautical star feature database, vector in the proper vector of primary and nautical star feature database being thought carries out matching ratio comparatively, calculate the similarity of the vector in proper vector and the nautical star feature database of primary, thus obtain the result of identification.

Further, needed before obtaining primary proper vector in the combined mode:

Calculate the coordinate of nautical star in star map image: according to the coordinate of nautical star in inertial coordinates system, according to certain transformation rule, calculate the coordinate of nautical star in star map image;

Determine the star pattern of primary: get a certain observation star in visual field as primary, according to the size of the radius of neighbourhood, determine the adjacent star of primary, be made up of the star pattern of primary primary and adjacent star.

Further, the coordinate conversion of nautical star in inertial coordinates system is as follows to the conversion formula of the coordinate in star map image:

$\begin{array}{c}{x}_r=\frac{N_x\×\cos \mathrm{\δ}\sin ({\mathrm{\α}}_i-\mathrm{\α})}{2\×\tan ({\mathrm{FOV}}_x/2)\×(\sin {\mathrm{\δ}}_i\×\sin \mathrm{\δ}+\cos {\mathrm{\δ}}_i\×\cos \mathrm{\δ}\×\cos ({\mathrm{\α}}_i-\mathrm{\α}))}\\ y_r=\frac{N_y\×(\sin {\mathrm{\δ}}_i\×\cos \mathrm{\δ}-\cos {\mathrm{\δ}}_i\×\sin \mathrm{\δ}\×\cos ({\mathrm{\α}}_i-\mathrm{\α}))}{2\×\tan ({\mathrm{FOV}}_y/2)\×(\sin {\mathrm{\δ}}_i\×\sin \mathrm{\δ}+\cos {\mathrm{\δ}}_i\×\cos \mathrm{\δ}\×\cos ({\mathrm{\α}}_i-\mathrm{\α}))}\end{array};$

Wherein, (N _x, N _y) be the resolution of CCD in star sensor, (FOV _x, FOV _y) be the size of CCD visual field, (α _i, δ _i) be respectively the right ascension declination observing star, the optical axis direction that (α, δ) is CCD; The optical axis of CCD points to the position of nautical star in inertial coordinate all the time, and this nautical star projects to the center of star map image.

Further, choose field of view center or near the observation star of field of view center as primary, in the hope of obtaining the complete star pattern of primary; According to the size of neighborhood and the position of primary, determine the positional information of the adjacent star of primary, be made up of the star pattern of primary the positional information of primary and adjacent star.

Further, the feature of primary under radial mode: the neighborhood of primary is on average divided into n endless belt along the radial direction of primary, add up the mean level of the sea distance of adjacent star on each endless belt and primary, use mean level of the sea distance on n endless belt as the feature of primary in radial mode.

Further, the mean level of the sea distance concrete grammar of the adjacent star on each endless belt and primary is:

N endless belt is labeled as C0 from inside to outside successively, C1, Cn-1, the radius of neighbourhood of primary is R, then i-th (i=0 ... n-1) inner boundary of individual endless belt and outer boundary are expressed as i*R/n and (i+1) * R/n, and the coordinate being positioned at the adjacent star on i-th endless belt should meet following condition:

$i\&times;R/n<\sqrt{{(x-x_0)}^2+{(y-y_0)}^2}\&le;(i+1)\&times;R/n,$ i＝0,…,n-1；

Wherein, (x0, y0) and (x, y) is respectively primary and the center-of-mass coordinate of adjacent star on star map image, and n is that primary neighborhood is by the endless belt number on average divided;

On each endless belt the number of adjacent star be expressed as Ni (i=0 ..., n-1), the mean level of the sea distance of the adjacent star on primary and i-th endless belt is expressed as:

$D_i=\frac{1}{N_i}\underset{j=1}{\overset{N_i}{\mathrm{\&Sigma;}}}\sqrt{{(x_{\mathrm{ij}}-x_0)}^2+{(y_{\mathrm{ij}}-y_0)}^2},$ i＝0,…n-1；

Wherein, (xij, yij) is the jth center-of-mass coordinate of adjacent star on star map image on i-th endless belt, and Ni is the number of adjacent star on i-th endless belt, and the mean level of the sea distance on n endless belt forms the feature of primary under radial mode, and it is expressed as:

D_vector＝{D ₀,D ₁,…,D _n-1}；

Further, the feature of primary under coding mode: the number of adding up adjacent star on each endless belt, uses default code base, encodes according to certain coding rule, and the encoded radio obtained is as the feature of primary in coding mode.

Further, the acquisition methods of encoded radio is:

The number of the adjacent star on i-th endless belt is N _i(i=1 ..., n), then the encoded radio that primary is corresponding under coding mode is expressed as:

$V_s=\underset{i=0}{\overset{n-1}{\mathrm{\&Sigma;}}}{N}_i{b}^{n-i-1};$

Wherein b is code base.

Further, primary proper vector is in the combined mode expressed as:

Vector＝{V _s,D_vector}；

In nautical star feature database, the record corresponding to each nautical star is expressed as:

Record＝{id,Vector}＝{id,V _s,D_vector}；

Wherein, id is the label of nautical star, V _sencoded radio corresponding to nautical star, namely nautical star is as the feature of primary under coding mode, and D_vector is for nautical star is as the feature of primary under radial mode that form of mean level of the sea distance of the adjacent star on n endless belt in primary and its neighborhood.

Further, the procedural representation of primary identification is:

result＝min{diff{Vector _s,Vector _c}},V _s∈Vector _s,V _c∈Vector _c,V _c∈[V _s-ε ₁,V _s-ε ₂]；

Wherein, V _sencoded radio in proper vector corresponding to nautical star s, V _cencoded radio in proper vector corresponding to the nautical star c in feature database, ε ₁and ε ₂for encoded radio institute tolerance.

Provided by the invention based on integrated mode from primary recognition methods, the proper vector of nautical star characterizes the feature of nautical star under radial mode and coding mode, there is translation rotational invariance, be applicable in star sensor from primary identification, without the need to searching for whole nautical star feature database in star identifying, can obtain the result identified rapidly, the process simplification of star identification is the single comparison between proper vector.

Beneficial effect of the present invention is:

1, the feature under radial mode has translation invariance, and the feature under coding mode has rotational invariance, and the advantage of radial mode and coding mode based on the characteristic set under integrated mode, is suitable for the star identification under complex environment;

2, utilize the scope of the encoded radio limit search corresponding to primary, improve the speed of star identification, enhance the sensitivity of system;

3, the star recognition methods based on integrated mode is simple, be easy to operation, simplifies the process of star identification, for star identification provides new thinking;

4, provided by the invention based on integrated mode from primary recognition methods, with prior art under identical conditions, performance is better than the recognition methods of existing pyramid star and based on the star recognizer of grid improved;

5, the star recognition methods based on integrated mode that the present invention is simple, quick and stable, can provide identifying information more accurately for the attitude algorithm of aircraft and navigator fix.

Accompanying drawing explanation

Fig. 1 be the embodiment of the present invention provide based on integrated mode from primary recognition methods process flow diagram;

Fig. 2 is fixed star in star sensor that the embodiment of the present invention provides is projected to star map image plane coordinate system imaging schematic diagram by inertial coordinates system;

Fig. 3 is the endless belt of the primary neighborhood division that the embodiment of the present invention provides;

Fig. 4 is the result schematic diagram of the nautical star feature database that the embodiment of the present invention provides.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

Below in conjunction with drawings and the specific embodiments, application principle of the present invention is further described.

As shown in Figure 1, the comprising the following steps from primary recognition methods based on integrated mode of the embodiment of the present invention:

S101: calculate the coordinate of nautical star in star map image: according to the coordinate of nautical star in inertial coordinates system, according to certain transformation rule, calculates the coordinate of nautical star in star map image;

S102: the star pattern determining primary: get a certain observation star in visual field as primary, according to the size of the radius of neighbourhood, determine the adjacent star of this primary, be made up of the star pattern of primary primary and its adjacent star;

S103: extract the feature of primary under radial mode: the neighborhood of primary is on average divided into n endless belt along the radial direction of primary, add up the mean level of the sea distance of adjacent star on each endless belt and primary, use mean level of the sea distance on n endless belt as the feature of primary in radial mode;

S104: extract the feature of primary under coding mode: the number of adding up adjacent star on each endless belt, uses default code base, encodes according to certain coding rule, and the encoded radio obtained is as the feature of primary in coding mode;

S105: the proper vector setting up primary: according to the feature of primary in radial mode and coding mode, obtains primary proper vector in the combined mode;

S106: the property data base generating nautical star: the optical axis of CCD is pointed to nautical star in fundamental catalog one by one, generates the proper vector corresponding to nautical star, and saves as the form of database;

S107: the result determining star identification: according to the feature of nautical star proper vector, the encoded radio corresponding to primary is utilized to limit its hunting zone in nautical star feature database, calculate the similarity of the vector in proper vector and the nautical star feature database of primary, thus obtain the result of identification.

In step S101, described nautical star is according to certain rule interestingness from basic fixed star storehouse; Use tycho 2 star catalogue as basic fixed star storehouse; In star catalogue, some star lacks monochrome information, and some star lacks positional information, and these stars all can not be used as nautical star; Due to the restriction of CCD resolution in star sensor, when two astrologies are apart from time nearer, can not be made a distinction clearly; Setting, when two astrologies are in time being less than 20 pixels (about 0.39 °), is regarded as double star; Double star can not be used for as nautical star; Therefore, in tycho 2 star catalogue, have 6685 fixed stars can as nautical star, its magnitude range be from 1.0mv to 6.5mv; The coordinate of nautical star in inertial coordinates system obtains from basic fixed star storehouse, so the master database of the positional information composition nautical star of nautical star.

In step S101, the coordinate conversion of nautical star in inertial coordinates system is as follows to the conversion formula of the coordinate in star map image:

$\begin{array}{c}{x}_r=\frac{N_x\&times;\cos \mathrm{\&delta;}\sin ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;})}{2\&times;\tan ({\mathrm{FOV}}_x/2)\&times;(\sin {\mathrm{\&delta;}}_i\&times;\sin \mathrm{\&delta;}+\cos {\mathrm{\&delta;}}_i\&times;\cos \mathrm{\&delta;}\&times;\cos ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;}))}\\ y_r=\frac{N_y\&times;(\sin {\mathrm{\&delta;}}_i\&times;\cos \mathrm{\&delta;}-\cos {\mathrm{\&delta;}}_i\&times;\sin \mathrm{\&delta;}\&times;\cos ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;}))}{2\&times;\tan ({\mathrm{FOV}}_y/2)\&times;(\sin {\mathrm{\&delta;}}_i\&times;\sin \mathrm{\&delta;}+\cos {\mathrm{\&delta;}}_i\&times;\cos \mathrm{\&delta;}\&times;\cos ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;}))}\end{array}$

Wherein, (N _x, N _y) be the resolution of CCD in star sensor, (FOV _x, FOV _y) be the size of CCD visual field, (α _i, δ _i) be respectively the right ascension declination observing star, the optical axis direction that (α, δ) is CCD; The optical axis of CCD points to the position of nautical star in inertial coordinate all the time, and this nautical star projects to the center of star map image.

Due to the restriction of CCD visual field size in step S102, the observation star being positioned at field of view edge has lacked a part of adjacent star, causes a large amount of geological information disappearances of its star pattern, so the star pattern corresponding to it is incomplete; So, choose field of view center or near the observation star of field of view center as primary, in the hope of obtaining the complete star pattern of primary; According to the size of neighborhood and the position of primary, determine the positional information of the adjacent star of primary, be made up of the star pattern of primary the positional information of primary and its adjacent star.

The border circular areas having a certain radius scope around primary in step S103 is the neighborhood of primary, the neighborhood of primary is on average divided into n endless belt along the radial direction of primary, adjacent star in neighborhood only belongs to a certain endless belt, the positional information on star map image according to primary and its adjacent star, adds up the mean level of the sea distance of adjacent star on each endless belt and primary; Specific practice is:

If n endless belt is labeled as C0, C1 from inside to outside successively ..., Cn-1, the radius of neighbourhood of primary is R, then i-th (i=0 ..., n-1) and the inner boundary of individual endless belt and outer boundary be expressed as i*R/n and (i+1) * R/n; Therefore, the coordinate being positioned at the adjacent star on i-th endless belt should meet following condition:

$i\&times;R/n<\sqrt{{(x-x_0)}^2+{(y-y_0)}^2}\&le;(i+1)\&times;R/n,$ i＝0,…,n-1；

Wherein, (x0, y0) and (x, y) is respectively primary and the center-of-mass coordinate of adjacent star on star map image, and n is that primary neighborhood is by the endless belt number on average divided;

If on each endless belt the number of adjacent star be expressed as Ni (i=0 ..., n-1), the mean level of the sea distance of the adjacent star on primary and i-th endless belt can be expressed as:

$D_i=\frac{1}{N_i}\underset{j=1}{\overset{N_i}{\mathrm{\&Sigma;}}}\sqrt{{(x_{\mathrm{ij}}-x_0)}^2+{(y_{\mathrm{ij}}-y_0)}^2},$ i＝0,…n-1

Wherein, (xij, yij) is the jth center-of-mass coordinate of adjacent star on star map image on i-th endless belt, and Ni is the number of adjacent star on i-th endless belt.

Add up the number of adjacent star on each endless belt in step S104, use default code base, encode according to certain coding rule, the encoded radio obtained is as the feature of primary in coding mode; If the number of the adjacent star on i-th endless belt is N _i(i=1 ..., n), then the encoded radio that primary is corresponding under coding mode can be expressed as:

$V_s=\underset{i=0}{\overset{n-1}{\mathrm{\&Sigma;}}}{N}_i{b}^{n-i-1};$

Wherein b is code base.

In conjunction with the advantage of radial mode and coding mode in step S105, the mean level of the sea distance of the adjacent star on primary and each endless belt is used to state the feature of primary in radial mode, encoded radio is used to describe the feature of primary in coding mode, the proper vector of primary is represented, so primary proper vector in the combined mode can be expressed as by the feature of primary under the integrated mode of radial mode and coding mode:

Vector＝{V _s,D ₀,D ₁,…,D _n+1}＝{V _s,D_vector}。

In step S106, property data base saves the eigenvector information corresponding to all nautical stars; CCD in star sensor points to selected nautical star one by one, obtains the position of observation star on star map image of distribution in visual field, according to the create-rule of proper vector, obtains the proper vector corresponding to primary, and be kept in nautical star feature database; Vector in nautical star feature database is in the absence of any noise, and observation star is as the proper vector corresponding to primary; From description above, in nautical star feature database, the record corresponding to each nautical star can be expressed as:

Record＝{id,Vector}＝{id,V _s,D_vector}

Wherein, id is the label of nautical star, V _sencoded radio corresponding to nautical star, also namely nautical star as the feature of primary under coding mode, D_vector for nautical star as the mean level of the sea of the adjacent star on n endless belt in primary and its neighborhood apart from the feature of primary under radial mode formed.

Star identifying described in step S107 is for an arbitrary width star map image, choose a certain observation star on star map image as primary, build the feature of this primary under radial mode and coding mode, the encoded radio corresponding to primary is utilized to limit its hunting zone in nautical star feature database, calculate the similarity of the vector in the proper vector of primary and nautical star feature database, judge that whether two proper vectors are consistent or similar, thus determine whether this observation star is corresponding nautical star, thus obtain the result of identification.

Hunting zone during described in step s 107 restriction star identification in nautical star feature database is and utilizes the encoded radio corresponding to primary to limit its hunting zone in nautical star feature database.Because of the impact of noise or other disturbing factors, observation star as compared with the encoded radio corresponding to primary, has certain difference as the encoded radio corresponding to primary and same observation star in the absence of any noise.During star identification, only allow the nautical star corresponding to encoded radio in feature database within the scope of different to carry out match cognization, in the hunting zone limited, use a small amount of ratio to obtain the result identified more quickly, and without the need to searching for whole nautical star feature database.The process of star identification can be expressed as:

result＝min{diff{Vector _s,Vector _c}},V _s∈Vector _s,V _c∈Vector _c,V _c∈[V _s-ε ₁,V _s-ε ₂]

Wherein, V _sencoded radio in proper vector corresponding to nautical star s, V _cencoded radio in proper vector corresponding to the nautical star c in feature database, ε ₁and ε ₂for encoded radio institute tolerance.

As shown in Figure 2, nautical star adopt in star map image the coordinate in x-axis and y-axis to characterize its picture plane on position; Nautical star is according to certain rule interestingness from fundamental catalog, and nautical star needs to comprise complete positional information and monochrome information, and adjacent nearer fixed star is regarded as double star, can not as nautical star; The light from fixed star arriving star sensor is thought for parallel rays, and its CCD at star sensor is a bright spot as disperse in plane, and the fixed star pointed by CCD optical axis projects to the center of picture plane; The coordinate conversion of nautical star in inertial coordinates system is as follows to the conversion formula of the coordinate in star map image:

$\begin{array}{c}{x}_r=\frac{N_x\&times;\cos \mathrm{\&delta;}\sin ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;})}{2\&times;\tan ({\mathrm{FOV}}_x/2)\&times;(\sin {\mathrm{\&delta;}}_i\&times;\sin \mathrm{\&delta;}+\cos {\mathrm{\&delta;}}_i\&times;\cos \mathrm{\&delta;}\&times;\cos ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;}))}\\ y_r=\frac{N_y\&times;(\sin {\mathrm{\&delta;}}_i\&times;\cos \mathrm{\&delta;}-\cos {\mathrm{\&delta;}}_i\&times;\sin \mathrm{\&delta;}\&times;\cos ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;}))}{2\&times;\tan ({\mathrm{FOV}}_y/2)\&times;(\sin {\mathrm{\&delta;}}_i\&times;\sin \mathrm{\&delta;}+\cos {\mathrm{\&delta;}}_i\&times;\cos \mathrm{\&delta;}\&times;\cos ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;}))}\end{array}$

Wherein, (N _x, N _y) be the resolution of CCD in star sensor, (FOV _x, FOV _y) be the size of CCD visual field, (α _i, δ _i) be respectively the right ascension declination observing star, the optical axis direction that (α, δ) is CCD; The optical axis of CCD points to the position of nautical star in inertial coordinate all the time.

As shown in Figure 3, the observation star of field of view center or close field of view center is chosen as primary S _saccording to the Size of Neighborhood R of primary, the observation star being positioned at contiguous range is regarded as the adjacent star of primary, the neighborhood of primary is on average divided into n endless belt along the radial direction of primary, adjacent star in neighborhood only belongs to a certain endless belt, the positional information on star map image according to primary and its adjacent star, adds up the mean level of the sea distance of adjacent star on each endless belt and primary; Specific practice is:

If n endless belt is labeled as C0, C1 from inside to outside successively ..., Cn-1, the radius of neighbourhood of primary is R, then i-th (i=0 ..., n-1) and the inner boundary of individual endless belt and outer boundary be expressed as i*R/n and (i+1) * R/n; Therefore, the coordinate being positioned at the adjacent star on i-th endless belt should meet following condition:

$i\&times;R/n<\sqrt{{(x-x_0)}^2+{(y-y_0)}^2}\&le;(i+1)\&times;R/n,$ i＝0,…,n-1；

Wherein, (x0, y0) and (x, y) is respectively primary and the center-of-mass coordinate of adjacent star on star map image, and n is that primary neighborhood is by the endless belt number on average divided;

If on each endless belt the number of adjacent star be expressed as Ni (i=0 ..., n-1), the mean level of the sea distance of the adjacent star on primary and i-th endless belt can be expressed as:

$D_i=\frac{1}{N_i}\underset{j=1}{\overset{N_i}{\mathrm{\&Sigma;}}}\sqrt{{(x_{\mathrm{ij}}-x_0)}^2+{(y_{\mathrm{ij}}-y_0)}^2},$ i＝0,…n-1

Wherein, (xij, yij) is the jth center-of-mass coordinate of adjacent star on star map image on i-th endless belt, and Ni is the number of adjacent star on i-th endless belt.

As shown in Figure 4, different nautical stars may have identical encoded radio, and some encoded radios only corresponding a certain nautical star, namely also exist between nautical star and encoded radio one to one with the relation of one-to-many; Utilize this feature, propose first according to the encoded radio determination candidate matches result of observation star, the mean level of the sea distance between recycling primary and adjacent star obtains final recognition result from candidate matches result; In addition, due to the impact of noise, the encoded radio of same observation star has certain floating, and therefore, when identifying, only need contrast the encoded radio being positioned at a certain mobility scale just can obtain candidate matches result, and without the need to searching for whole nautical star feature database; So, just according to a small amount of comparison, just can obtain the result identified, accelerate the speed of star identification.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. based on integrated mode from a primary recognition methods, it is characterized in that, should based on integrated mode from primary recognition methods:

The contiguous range of primary is divided into equally spaced endless belt from inside to outside, and the mean level of the sea distance of the adjacent star on primary and each endless belt forms the feature of primary under radial mode; The number of adjacent star on each endless belt, the encoded radio utilizing code base to obtain is the feature of primary under coding mode; The structural feature primary proper vector in the combined mode of combination primary under radial mode and coding mode;

The optical axis of CCD is pointed to one by one the nautical star in fundamental catalog, generate the proper vector corresponding to nautical star, and save as the form of database, form the feature database of nautical star;

The encoded radio in primary proper vector is utilized to reduce the hunting zone in nautical star feature database, the proper vector of primary is mated with the proper vector in nautical star feature database, calculate the similarity of the proper vector in proper vector and the nautical star feature database of primary, thus obtain the result of identification.

2. as claimed in claim 1 based on integrated mode from primary recognition methods, it is characterized in that, needed before obtaining primary proper vector in the combined mode:

Calculate the coordinate of nautical star in star map image: according to the coordinate of nautical star in inertial coordinates system, according to certain transformation rule, calculate the coordinate of nautical star in star map image;

Determine the star pattern of primary: get a certain observation star in visual field as primary, according to the size of the radius of neighbourhood, determine the adjacent star of primary, be made up of the star pattern of primary primary and adjacent star.

3. as claimed in claim 2 based on integrated mode from primary recognition methods, it is characterized in that, the coordinate conversion of nautical star in inertial coordinates system is as follows to the conversion formula of the coordinate in star map image:

$\begin{array}{c}{x}_r=\frac{N_x\&times;\cos \mathrm{\&delta;}\sin ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;})}{2\&times;\tan ({\mathrm{FOV}}_x/2)\&times;(\sin {\mathrm{\&delta;}}_i\&times;\sin \mathrm{\&delta;}+\cos {\mathrm{\&delta;}}_i\&times;\cos \mathrm{\&delta;}\&times;\cos ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;}))}\\ y_r=\frac{N_y\&times;(\sin {\mathrm{\&delta;}}_i\&times;\cos \mathrm{\&delta;}-\cos {\mathrm{\&delta;}}_i\&times;\sin \mathrm{\&delta;}\&times;\cos ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;}))}{2\&times;\tan ({\mathrm{FOV}}_y/2)\&times;(\sin {\mathrm{\&delta;}}_i\&times;\sin \mathrm{\&delta;}+\cos {\mathrm{\&delta;}}_i\&times;\cos \mathrm{\&delta;}\&times;\cos ({\mathrm{\&alpha;}}_i-\mathrm{\&alpha;}))}\end{array};$

Wherein, (N _x, N _y) be the resolution of CCD in star sensor, (FOV _x, FOV _y) be the size of CCD visual field, (α _i, δ _i) be respectively the right ascension declination observing star, the optical axis direction that (α, δ) is CCD; The optical axis of CCD points to the position of nautical star in inertial coordinate all the time, and this nautical star projects to the center of star map image.

4. as claimed in claim 2 based on integrated mode from primary recognition methods, it is characterized in that, choose field of view center or near the observation star of field of view center as primary, in the hope of obtaining the complete star pattern of primary; According to the size of neighborhood and the position of primary, determine the positional information of the adjacent star of primary, be made up of the star pattern of primary the positional information of primary and adjacent star.

5. as claimed in claim 1 based on integrated mode from primary recognition methods, it is characterized in that, the feature of primary under radial mode: the neighborhood of primary is equidistantly divided into n endless belt along the radial direction of primary, add up the mean level of the sea distance of adjacent star on each endless belt and primary, use mean level of the sea distance on n endless belt as the feature of primary in radial mode.

6. as claimed in claim 5 based on integrated mode from primary recognition methods, it is characterized in that, the mean level of the sea of the adjacent star on each endless belt and primary apart from concrete grammar is:

N endless belt is labeled as C0 from inside to outside successively, C1, Cn-1, the radius of neighbourhood of primary is R, then i-th (i=0 ... n-1) inner boundary of individual endless belt and outer boundary are expressed as i*R/n and (i+1) * R/n, and the coordinate being positioned at the adjacent star on i-th endless belt meets following condition:

$i\&times;R/n<\sqrt{{(x-x_0)}^2+{(y-y_0)}^2}\&le;(i+1)\&times;R/n,i=0,...,n-1;$

Wherein, (x0, y0) and (x, y) is respectively primary and the center-of-mass coordinate of adjacent star on star map image, and n is that primary neighborhood is by the endless belt number on average divided;

On each endless belt the number of adjacent star be expressed as Ni (i=0 ..., n-1), the mean level of the sea distance of the adjacent star on primary and i-th endless belt is expressed as:

$D_i=\frac{1}{N}\underset{j=1}{\overset{N_i}{\mathrm{\&Sigma;}}}\sqrt{{(x_{\mathrm{ij}}-x_0)}^2+{(y_{\mathrm{ij}}-y_0)}^2},i=0,...n-1;$

Wherein, (xij, yij) is the jth center-of-mass coordinate of adjacent star on star map image on i-th endless belt, and Ni is the number of adjacent star on i-th endless belt, and the mean level of the sea distance on n endless belt forms the feature of primary under radial mode, is expressed as:

D_vector＝{D ₀,D ₁,…,D _n-1}。

7. as claimed in claim 1 based on integrated mode from primary recognition methods, it is characterized in that, the feature of primary under coding mode: the number of adding up adjacent star on each endless belt, use default code base, encode according to certain coding rule, the encoded radio obtained is as the feature of primary in coding mode.

8. as claimed in claim 7 based on integrated mode from primary recognition methods, it is characterized in that, the acquisition methods of encoded radio is:

The number of the adjacent star on i-th endless belt is N _i(i=1 ..., n), then the encoded radio that primary is corresponding under coding mode is expressed as:

$V_s=\underset{i=0}{\overset{n-1}{\mathrm{\&Sigma;}}}{N}_i{b}^{n-i-1};$

Wherein b is code base.

9. as claimed in claim 1 based on integrated mode from primary recognition methods, it is characterized in that, in conjunction with the structural feature primary feature in the combined mode of primary under radial mode and coding mode, primary proper vector is in the combined mode expressed as:

Vector＝{V _s,D_vector}；

In nautical star feature database, the record corresponding to each nautical star is expressed as:

Record＝{id,Vector}＝{id,V _s,D_vector}；

Wherein, id is the label of nautical star, V _sencoded radio corresponding to nautical star, namely nautical star is as the feature of primary under coding mode, and D_vector is for nautical star is as the feature of primary under radial mode that form of mean level of the sea distance of the adjacent star on n endless belt in primary and neighborhood.

10. as claimed in claim 1 based on integrated mode from primary recognition methods, it is characterized in that, the procedural representation of primary identification is:

result＝min{diff{Vector _s,Vector _c}},V _s∈Vector _s,V _c∈Vector _c,V _c∈[V _s-ε ₁,V _s-ε ₂]；

Wherein, V _sencoded radio in proper vector corresponding to nautical star s, V _cencoded radio in proper vector corresponding to the nautical star c in feature database, ε ₁and ε ₂for encoded radio institute tolerance.