Disclosure of Invention
The invention aims to provide a space debris real-time astronomical positioning and photometry method based on automatic direction measurement, which can automatically select a negative film model according to the size of an observation field, automatically measure the center direction and the image surface rotation angle of an image according to the given time on the image, realize the automatic matching of a fixed star theoretical coordinate and an actually measured coordinate, realize the automatic matching of a fixed star gray value and a theoretical star thereof on the image, and further realize the real-time astronomical positioning and photometry of the space debris. For a telescope with a fixed station address (with precise astronomical longitude and latitude), the method reduces the requirement on the machining precision of a telescope axis, reduces the requirement on the installation and debugging of an external field of the telescope, reduces the requirement on the environmental temperature reference input of a survey station, and reduces the requirement on pointing calibration before observation. For a movable telescope, the method can automatically measure the zero point difference of two axes of the telescope and can also realize real-time astronomical positioning and relative photometry of space debris under the condition that pointing calibration of the telescope cannot be realized without precise astronomical longitude and latitude. More importantly, the method can realize high-precision astronomical positioning and relative photometry on a mobile station site without astronomical longitude and latitude (only geographical longitude and latitude).
To achieve the above object, with reference to fig. 1, the present invention provides a real-time astronomical positioning and light measuring method for space debris based on automatic pointing measurement, wherein the real-time astronomical positioning and light measuring method comprises the following steps:
s1: generating an astronomical positioning fixed star library and first index data for expressing self information of all fixed stars contained in the astronomical positioning fixed star library; generating a whole-day-area theoretical star map and second index data for expressing angular distance information between stars contained in the whole-day-area theoretical star map based on an astronomical positioning star library;
s2: receiving at least one frame of image comprising space debris and background stars, and obtaining star image information of the stars and the space debris on the image within a preset detection threshold; calculating to obtain the angular distance between any two fixed stars based on the obtained star image information of the fixed stars, and generating a fixed star actual measurement star map;
s3: according to the theoretical star map of the whole day region and the second index data, the upper and lower limits of the actually measured star map of the fixed star are determined, and the maximum angular distance is obtained
Minimum angular distance
Intermediate angular distance
Combined maximum angular distance
Minimum angular distance
Intermediate angular distance
According to a preset matching rule, calculating to obtain a plurality of fixed star planets which are contained in an actually measured fixed star atlas and are matched with a theoretical star atlas of an all-day area;
s4: calculating to obtain center pointing deviation, image surface rotation angle, negative film constant model and relative photometric model based on the successfully matched star image information;
wherein, the photometry model is:
wherein G is
iThe gray value of the ith successfully matched star-star image after background subtraction,
is a theoretical star corresponding to the ith successfully matched star-star image, i is 1,2, …, N
3,N
3Is the total number of successfully matched star stars, and A and B are relative photometric model coefficients calculated by a least square method.
In a further embodiment, in step S2, the process of generating the measured star map of the fixed star includes the following steps:
selecting N from the image according to a given threshold1The star image of the fixed star is defined as a first candidate fixed star, the angular distance between any two first candidate fixed stars is obtained through calculation by combining the two-dimensional plane coordinates of the first candidate fixed star on the image and the focal length of the telescope, three first candidate fixed stars are selected to form a triangular star map, and a fixed star actual measurement star map is generated;
the angular distance between any two first candidate stars is calculated by adopting the following formula:
where f is the focal length of the telescope, (x)j,yj) Is the two-dimensional plane coordinate of the jth first candidate star, (x)k,yk) Is the two-dimensional plane coordinates of the kth first candidate star.
In a further embodiment, in step S1, the generating an astronomical positioning star base and the first index data for describing all star self information included in the astronomical positioning star base includes:
and storing the fixed stars in the whole day area of the given star and the like in a partitioning manner according to the increasing order of the right ascension and the increasing order of the declination, forming an index, and generating an astronomical positioning fixed star library and index data.
In a further embodiment, in step S1, the generating of the all-day-region theoretical star map and the second index data used for expressing the angular distance information between stars included in the all-day-region theoretical star map based on the astronomical positioning star library includes:
selecting a whole day region N according to a given star equal threshold2And the particle star elephant is defined as a second candidate star, the angular distance between any two second candidate stars is obtained through calculation by combining the right ascension and the declination of the second candidate stars, a triangular star map is formed by optionally selecting three second candidate stars according to a given angular distance threshold, a theoretical star map of the whole day area is generated, and the theoretical star map is sorted according to the angular distance of each triangle to generate corresponding index data.
In a further embodiment, in step S1, the angular distance between any two second candidate stars is calculated by the following formula:
wherein (alpha)u,δu) Is the right ascension and declination of the u-th second candidate star, (alpha)v,δv) Is the right ascension and declination, σ, of the v-th second candidate starc u,vIs the angular distance between the u-th and v-th second candidate stars.
In a further embodiment, in step S3, the step of calculating, according to a preset matching rule, a plurality of pieces of star stellar information which are included in the actually measured star atlas of the fixed star and are matched with the theoretical star atlas of the whole sky area includes the following steps:
s31: determining the upper and lower limits of the candidate star atlas according to the all-day area theoretical star atlas and the second index data, and acquiring the maximum angular distance
Minimum angular distance
Intermediate angular distance
S32: sequentially calculating the angular distance of a triangle formed by any three calibration stars i, j and k in the upper and lower boundaries, and setting the sequence of the calculated angular distances from large to small as
According to the following matching conditions, the calculated angular distance is calculated
Correspond to
Carrying out matching judgment until the matching is successful N
3Particle fixed stars:
the jth scaling star and the kth scaling star satisfy the following formula:
the following formula is satisfied between any three i, j, k calibration stars:
wherein epsilon1And ε2All are preset angular distance thresholds;
in a further embodiment, in step S4, the process of calculating the center pointing deviation and the image plane rotation angle based on the information of the plurality of star planets successfully matched includes the following steps:
n for successful design matching3The two-dimensional plane coordinate of the particle fixed star on the image is (x)i,yi),i=1,2,…N3The corresponding theoretical two-dimensional plane coordinate is (X)i,Yi),i=1,2,…N3;
Calculating coefficients a, b, c, d, e and f by using a least square method according to the following formula, so as to obtain a center pointing deviation and an image plane rotation angle:
in a further embodiment, in step S4, the acquiring process of the negative film constant model includes the following steps:
combining the astronomical positioning fixed star library and the first index data, and according to the shooting information corresponding to the image and the whole-day star map pointing measurement result (alpha)p,δp) Retrieving relevant information of all fixed stars meeting a given star equal threshold in the field of view, wherein the relevant information of the fixed stars meeting the given star equal threshold comprises corresponding two-dimensional plane coordinate theoretical values (X, Y), right ascension and declination theoretical values (alpha)s,δs) Ideal coordinate theoretical value (xi)s,ζs) The M such as theoretical stars and the like sort the searched fixed stars according to the sequence from small to large of the theoretical stars and the like; wherein the ideal coordinates (ξ)s,ζs) The following formula is satisfied:
the shooting information corresponding to the image comprises shooting time of the image, pointing information, longitude and latitude of the measuring station, altitude of the measuring station, temperature of the measuring station, humidity of the measuring station, atmospheric pressure and given view field size;
combining the successfully matched N according to the size of the corresponding view field of the image
3Two-dimensional plane coordinate (x) of particle fixed star on image
i,y
i) And ideal coordinates
i=1,2,…N
3And calculating a constant model, automatically optimizing the film constant model according to the positioning accuracy of the fixed star, and automatically storing the optimized film constant model.
In a further embodiment, said performing constant model calculations comprises,
and (3) combining the number of successfully matched calibration stars, and respectively selecting a six-constant model, a twelve-constant model and a fourteen-constant model for constant model calculation, wherein:
the six-constant model corresponds to at least 3 calibration stars:
the twelve constant model corresponds to at least 6 calibration stars:
the fourteen-constant model corresponds to at least 7 calibration stars:
in a further embodiment, the real-time astronomical positioning method further comprises:
s5: according to the two-dimensional plane coordinate measured value (x) of the space debrisT,yT) Is adopted toThe following formula obtains the right ascension and declination (alpha) of the space debrisT,δT):
Wherein (xi)T,ζT) Is the ideal coordinate of space debris, consisting ofT,yT) And substituting a six-constant model, a twelve-constant model or a fourteen-constant model to obtain the model.
Compared with the prior art, the technical proposal of the invention has the obvious beneficial effects that,
(1) the negative film model can be automatically optimized according to the size of an observation view field, the image center pointing direction and the image surface rotation angle are automatically measured according to the given time and the image center pointing direction on the image, and the automatic matching of the fixed star theoretical coordinate and the actual measurement coordinate is realized, so that the real-time astronomical positioning and photometry of space debris are realized.
(2) For a telescope with a fixed station address (with precise astronomical longitude and latitude), the method reduces the requirement on the machining precision of a telescope axis, reduces the requirement on the installation and debugging of an external field of the telescope, reduces the requirement on the environmental temperature reference input of a survey station, and reduces the requirement on pointing calibration before observation. For the movable telescope, the method can realize real-time astronomical positioning and relative photometry of space debris under the condition that pointing calibration of the telescope cannot be realized without precise astronomical longitude and latitude. Therefore, the method is a very good space debris real-time astronomical positioning and light measuring method.
(3) The method can realize high-precision astronomical positioning and relative photometry on a mobile station site without astronomical longitude and latitude (only geographical longitude and latitude), has good actual processing effect, and can be widely applied to the fields of scientific research and engineering.
(4) The computer system can give space debris astronomical positioning results, fixed star astronomical positioning results, pointing image plane rotation measuring results and fixed star retrieval results on the images in real time. The results are widely applied, for example, the results can be displayed by a display system, stored in a storage medium of a computer system, used for cataloging and precisely tracking the space debris, and corrected according to the pointing measurement result, so that the capturing and tracking success rate of the space debris can be improved.
It should be understood that all combinations of the foregoing concepts and additional concepts described in greater detail below can be considered as part of the inventive subject matter of this disclosure unless such concepts are mutually inconsistent. In addition, all combinations of claimed subject matter are considered a part of the presently disclosed subject matter.
The foregoing and other aspects, embodiments and features of the present teachings can be more fully understood from the following description taken in conjunction with the accompanying drawings. Additional aspects of the present invention, such as features and/or advantages of exemplary embodiments, will be apparent from the description which follows, or may be learned by practice of specific embodiments in accordance with the teachings of the present invention.
Detailed Description
In order to better understand the technical content of the present invention, specific embodiments are described below with reference to the accompanying drawings.
With reference to fig. 1, the present invention provides a real-time astronomical positioning and photometry method for space debris based on automatic pointing measurement, comprising the following steps:
s1: generating an astronomical positioning fixed star library and first index data for expressing self information of all fixed stars contained in the astronomical positioning fixed star library; and generating a whole-day-region theoretical star map and second index data for expressing the angular distance information between the stars contained in the whole-day-region theoretical star map based on the astronomical positioning star library.
S2: receiving at least one frame of image comprising space debris and background stars, and obtaining star image information of the stars and the space debris on the image within a preset detection threshold; and calculating to obtain the angular distance between any two fixed stars based on the acquired star image information of the fixed stars, and generating the actually measured star map of the fixed stars.
S3: according to the theoretical star map of the whole day region and the second index data, the upper and lower limits of the actually measured star map of the fixed star are determined, and the maximum angular distance is obtained
Minimum angular distance
Intermediate angular distance
Combined maximum angular distance
Minimum angular distance
Intermediate angular distance
And according to a preset matching rule, calculating to obtain a plurality of fixed star planets which are contained in the fixed star actual measurement star atlas and are matched with the all-day area theoretical star atlas.
S4: and calculating to obtain center pointing deviation, image surface rotation angle, negative film constant model and relative photometric model based on the information of a plurality of star planets successfully matched.
Wherein, the photometry model is:
wherein G is
iIs that the ith matching is successfulThe gray value of the star-star image after deducting the background,
is a theoretical star corresponding to the ith successfully matched star-star image, i is 1,2, …, N
3,N
3Is the total number of successfully matched star stars, and A and B are relative photometric model coefficients calculated by a least square method.
Briefly, the technical scheme of the invention comprises the following working steps:
(1) and generating a theoretical star map.
(2) Stars and space debris stars.
(3) And generating an actual measurement star map.
(4) And matching the theoretical star map with the actual measurement star map.
(5) And measuring the direction and the image plane rotation.
(6) And (5) searching stars.
(7) The negative model is preferred.
(8) And (5) calculating a photometric model.
(9) Space debris astronomical localization.
In practical application, after acquiring star image information of stars and space debris on each frame of image through space target detection aiming at the collected continuous observation images, the 9 steps are sequentially adopted to acquire astronomical positioning and photometric data of the space debris. More optimally and more specifically describing the above steps as follows:
first, theoretical star map generation
And storing the stars in all-day regions of the given star and the like in a partitioning manner according to the increasing order of the right ascension and the increasing order of the declination, forming an index, and generating an astronomical positioning star database and first index data for searching the stars. Selecting a whole day region N according to a given star equal threshold2The star image of the particle stars calculates the angular distance between any two fixed stars by adopting the following formula according to the information of the right ascension and the declination of the fixed stars:
wherein (alpha)u,δu) Is the right ascension and declination of the u-th second candidate star, (alpha)v,δv) Is the right ascension and declination of the v second candidate star
And according to a given threshold, such as minimum and maximum angular distances, optionally selecting three stars to form a triangular star map, generating a theoretical star map of the whole sky area, and sorting according to the angular distance of each triangle. And generating a theoretical star atlas database of the whole day area and corresponding second index data for star atlas retrieval.
Second, fixed star and space debris astrology
According to the space debris detection method, star image information of stars and space debris on an image within a detection threshold is obtained, wherein the star image information comprises two-dimensional plane coordinates (x, y), the number of pixels, the gray sum, and the image is sorted according to the decreasing sequence of the number of pixels. Preferably, any space debris acquisition method in the prior art can be adopted to obtain star image information of stars and space debris within the detection threshold on the image. The left upper corner of the image is set as a coordinate origin (0, 0), the right side of the image is set as an x-axis increasing direction, the lower side of the image is set as a y-axis increasing direction, x is the distance between the position of the star in the image and the coordinate origin in the x-axis direction, and y is the distance between the position of the star in the image and the coordinate origin in the y-axis direction.
Third, actual measurement star map generation
According to a given threshold, selecting N1The focal length of the telescope is f according to the two-dimensional plane coordinates (x, y) of the star image of the fixed star. The angular distance between any two fixed stars is calculated by adopting the following formula, and three fixed stars are selected by people to form a triangular star map so as to generate an actual measurement star map of the fixed stars. Calculating the angular distance between any two first candidate stars by adopting the following formula:
wherein (x)j,yj) Is the two-dimensional plane coordinate of the jth second candidate star, (x)k,yk) Is the k second candidate starPlane coordinates.
Fourthly, matching the theoretical star map with the actual measurement star map
For any three calibration stars i, j, k on the image, the angular distance is formed in the order of magnitude
The triangles of (1) quickly realize the upper and lower boundaries n of the candidate star atlas according to the index of the theoretical star atlas, and the corresponding angular distances of the triangles in the upper and lower boundaries are in the order of magnitude
And (6) carrying out matching judgment.
Since f may not be too accurate, the relationship between the jth and kth calibration stars can still satisfy the following equation:
the following formula is satisfied between any three i, j, k calibration stars:
and
and fifthly, measuring the direction and the image plane rotation.
Suppose the matching is successful N3Fixed star, two-dimensional plane coordinate (x) of star on imagei,yi),i=1,2,…N3Theoretical two-dimensional planar coordinate (X) of a star imagei,Yi),i=1,2,…N3。
Calculating coefficients a, b, c, d, e and f by using a least square method according to the following formula, so as to obtain a center pointing deviation and an image plane rotation angle:
sixthly, searching stars.
According to the time corresponding to the image and the whole-day star map orientation measurement result (alpha)p,δp) The method comprises the steps of searching fixed star information which meets thresholds such as a given star and the like in a view field and comprises two-dimensional plane coordinate theoretical values (X, Y), right ascension and declination theoretical values (alpha)s,δs) Ideal coordinate theoretical value (xi)s,ζs) M such as theoretical stars and the like, and sequencing according to the increasing sequence of the theoretical stars and the like. The ideal coordinate (xi)s,ζs) The following formula is satisfied:
seventh, the negative film model is preferred.
According to the size of the corresponding field of view of the image, the matching is assumed to be successful N
3Fixed star, two-dimensional plane coordinate (x) of star on image
i,y
i) And ideal coordinates
i=1,2,…N
3. And (4) automatically optimizing the negative constant model according to the positioning precision of the fixed star by adopting the following six-constant, twelve-constant and fourteen-constant model calculation (the optimization is only needed once, and the optimization result is automatically stored).
Six constant model (need more than 3 calibration stars)
Twelve constant model (requiring more than 6 calibration stars)
Fourteen constant model (requiring more than 7 calibration stars)
Eight, photometric model calculation
Suppose the matching is successful N3The gray value of the particle star and the star image minus the background is GiAnd the corresponding theoretical star, etc. is Mi c,i=1,2,…,N3. Relative photometric model coefficients a and B were obtained using the following formula using the least squares method:
Mi c=Α+B log(Gi). LOG has 10 subscripts
And ninthly, astronomical positioning of the space debris.
According to the two-dimensional plane coordinate measured value (x) of the space debrisT,yT) The right ascension and declination (alpha) of the space debris are obtained using the following formulaT,δT):
Wherein (xi)T,ζT) Is the ideal coordinate of space debris, consisting ofT,yT) And substituting a six-constant model, a twelve-constant model or a fourteen-constant model to obtain the model.
And the computer system provides space debris astronomical positioning and light measuring results, fixed star astronomical positioning and light measuring results, pointed image plane rotation measuring results and fixed star retrieval results on the image in real time according to the input data. The results can be displayed by a display system, stored in a storage medium of a computer system, used for cataloging, orbit determination and precise orbit determination of the space debris, and the forecast positions of the space debris can be corrected according to the pointing measurement result, so that the capturing and tracking success rate of the space debris can be improved; the method can be used for space debris identification, and can be used for evaluating the working state, the rotating state and the like of the attitude control space target.
In this disclosure, aspects of the present invention are described with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present disclosure are not necessarily defined to include all aspects of the invention. It should be appreciated that the various concepts and embodiments described above, as well as those described in greater detail below, may be implemented in any of numerous ways, as the disclosed concepts and embodiments are not limited to any one implementation. In addition, some aspects of the present disclosure may be used alone, or in any suitable combination with other aspects of the present disclosure.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention should be determined by the appended claims.