CN101435704A - Star tracking method of star sensor under high dynamic state - Google Patents

Abstract

The invention provides a method for tracking a highly dynamic star with a star sensor. Firstly, according to ideal star image coordinate information predicted by a former frame of the star sensor, the corresponding star image coordinates are picked up from the present frame star chart, and by utilizing the star image coordinates picked up from the present frame star chart and celestial coordinates corresponding to the star images, the posture information of the present frame of the star sensor is worked out. The invention provides a method only adopting the autonomous posture of the star sensor to work out the actual output posture of the star sensor according to the predicted posture so as to meet the control requirements of high precision and non-spinning top when an aircraft maneuvers at big angular speed. With a star tracking algorithm provided by the method, before picking up the star image coordinates, the ideal star image centers are predicted according to the former frame, and the actual star image positions are picked up by referring to the ideal star image centers; the ideal star image coordinates of the next frame of the known star in the visual field are predicted and used as a basis for picking up the star image coordinates from the next frame star chart, so the requirements on real time and reliability when the aircraft maneuvering at the big angular speed only adopts the star sensor to navigate are met.

Description

Star tracking method under a kind of star sensor height is dynamic

(1) technical field

The present invention relates to a kind of measuring technique, only adopt star sensor to measure the attitude technology when being specifically related to the speed maneuver of a kind of explorer vehicle big angle.

(2) background technology

Star sensor is a kind of high-precision attitude of flight vehicle sensitive measurement instrument, and it determines attitude of flight vehicle by the fixed star of surveying diverse location on the celestial sphere, and the three-axis attitude of aerospacecraft with respect to inertial coordinates system is provided.At present a lot of scholars propose various whole day soccer star figure recognizers or improve various whole day soccer star figure recognizers and improve the star sensor data updating rate.Though these algorithms have improved attitude update rate to a certain extent, owing to before the whole day soccer star schemes identification, must from the view picture star chart, extract star as coordinate, and extraction star most times of having accounted for whole whole day soccer star figure recognition mode as coordinate.Along with the face battle array increase on picture plane, extract the time increase of star as the coordinate process at every turn.Yet wide visual field, big face battle array is the development trend of star sensor of new generation as the plane.So consider that from whole day soccer star figure recognizer the attitude update rate that improves star sensor must be restricted fully.Simultaneously, because the identification of whole day ball does not have the priori attitude information, the observation star must be carried out corresponding coupling with whole navigational star table.So star sensor is operated in the possibility that whole day ball recognition mode has also increased mistake identification purely, reduced the reliability of data.

In order further to improve the star sensor data updating rate, when enough prior imformations were arranged, star sensor was operated under the star tracing mode.Yet traditional star track algorithm extracts present frame fixed star star as coordinate time, is in the star chart subrange at center (as Fig. 1) as coordinate with the actual star of previous frame in the scanning star chart.When the speed maneuver of aircraft big angle, can be operated under traditional star tracing mode in order to make star sensor as far as possible, generally choose bigger scanning star chart zone as much as possible.If increase scanning star chart zone, increased the quantity of scanning star chart pixel in as the coordinate process extracting star so, thereby reduced data updating rate; Simultaneously owing to increased scanning star chart zone, increased and comprised other star picture part pixel or whole possibilities of pixels in regional, therefore to repeatedly adopt star that angular distance is relatively chosen correct star as coordinate, thus choose correct star as coordinate time increased the mistake coupling may.Increase the calculated amount of processor like this, thereby reduced data updating rate.Therefore during the speed maneuver of star sensor big angle, the star track algorithm that research has traditional advantages (high real-time, high precision and high reliability etc.) is the problem to be solved in the star sensor development.

(3) summary of the invention

The object of the present invention is to provide the high star tracking method under dynamically of the star sensor of a kind of high real-time, high precision and high reliability.

The object of the present invention is achieved like this: at first the desirable star according to the prediction of star sensor previous frame extracts corresponding star as coordinate as coordinate information from the present frame star chart, then according to the star that extracts as coordinate Calculation present frame attitude, utilize present frame attitude result and previous frame attitude result to predict the next frame attitude information, at last according to the attitude information of prediction predict in the present frame visual field all known fixed stars in the next frame star chart corresponding desirable star as coordinate, preserve the celestial coordinates of the desirable star of these predictions, extract the Given information of star as coordinate as star sensor next frame star chart as coordinate and corresponding star picture.

The present invention also has some technical characterictics like this:

1, described star sensor system partly is made up of probe segment, data processor, wherein probe segment comprise light shield, optical lens, imageing sensor, support circuit and with the interface of data processor, optical lens is arranged in the light shield, imageing sensor connects optical lens, support the circuit connection diagram image-position sensor, the interface of data processor is connection layout image-position sensor and data processor respectively; Data processor comprises computing machine, storer and the external interface that is connected probe segment, light signal in the celestial sphere at first passes through light shield, light shield passes through optical lens after eliminating the veiling glare of these light signals, be imaged in the imageing sensor of star sensor, imageing sensor is under the driven of supporting drives, light signal is converted to electric signal, form the correct star chart of a width of cloth, this star chart is kept in the storer of data processor part by interface with data processor, computing machine reads star chart information from storer, and this star chart handled, comprise and extract star as coordinate, importance in star map recognition, the Attitude Calculation process sends to the aircraft navigation computing machine to the information of calculating such as attitude result by external interface at last;

2, described star tracking method is: fixed star is imaged on star sensor as on the plane by the star sensor optical lens, and imaging circuit is converted into a complete star chart to the electric signal as fixed star in the plane, and is kept in the storer; The star picture extracts software and reads star chart data in the storer, extracts star as the method for coordinate to be from the present frame star chart: be to extract corresponding star as coordinate in the star chart among a small circle at center as coordinate with the previous frame star; Owing to comprised these known fixed star star pictures in celestial coordinates information in the prior imformation, so needn't look like to discern to these fixed star stars; Attitude Calculation software adopts corresponding Attitude Calculation algorithm, utilize star follow the tracks of to extract star as coordinate and prior imformation culminant star as celestial coordinates information, calculate current star sensor attitude information, and, send to the aircraft navigation computing machine by external interface;

3, described star is high dynamically star tracing mode as the coordinate recognition methods.

The present invention at first comes to extract corresponding star as coordinate according to the desirable star that the previous frame of star sensor is predicted as coordinate information from the present frame star chart, the star that utilizes present frame to extract then calculates the attitude information of star sensor present frame as the celestial coordinates of coordinate and these star picture correspondences.Adopt present frame star sensor attitude information and previous frame star sensor attitude information to predict the attitude information of star sensor next frame.Adopt the star sensor attitude information and the coordinate of all known fixed stars of present frame under celestial coordinate system of this prediction to predict the ideal coordinates of all known fixed stars of present frame in star sensor next frame star chart.The out of Memory such as attitude result that calculate the star sensor present frame are sent to the aircraft navigation computing machine.Preserve the celestial coordinates of the desirable star of these predictions simultaneously, extract the Given information of star as coordinate as star sensor next frame star chart as coordinate and corresponding star picture.

The high dynamically star tracking method that the present invention proposes is: fixed star is imaged on star sensor as on the plane by optical lens, by related circuit electric signal is converted into a complete star chart, and this star chart is exactly the star chart of star sensor present frame.Extracting known fixed star star from the star chart of present frame as coordinate method is: with the desirable star of previous frame prediction as coordinate S _i(i=1,2 ... n, wherein n is the quantity of known fixed star in the visual field, down together) be the center, be to extract the star of corresponding fixed star in star sensor present frame star chart as coordinate S in the round scope of radius with R _i' (i=1,2 ... n).Because these star pictures have been known fixed stars at previous frame, therefore the celestial coordinates of these star picture correspondences is known in present frame, therefore needn't look like to discern again to these stars.So the star that extracts according to present frame calculates the attitude information of star sensor present frame (being current time) as the celestial coordinates of coordinate and these star picture correspondences.According to present frame star sensor attitude information and previous frame star sensor attitude information, the forecast model of star sensor attitude is predicted the attitude information of star sensor next frame when utilizing the big angle speed maneuver.According to the star sensor attitude information and the coordinate of all known fixed stars of present frame under celestial coordinate system of this prediction, utilize the forecast model of big angle speed maneuver clock star inconocenter to predict the ideal coordinates of all known fixed stars of present frame in star sensor next frame star chart.By external interface, the out of Memory such as attitude result that calculate star sensor present frame (being current time) are sent to the aircraft navigation computing machine.Preserve the celestial coordinates of the desirable star of these predictions simultaneously, extract the Given information of star as coordinate as star sensor next frame star chart as coordinate and corresponding star picture.

The present invention mainly solves following two problems:

The forecast model of star sensor attitude during derivation big angle speed maneuver

Because of the demand of aircraft applications task, must controlling aircraft carry out the motor-driven adjustment of large-scale rapid posture at short notice, promptly turn to another predetermined targeted attitude from present attitude in the short time.Do not contain trigonometric function owing to adopt quaternary usually to describe attitude motion equation, and do not have the singular point problem.Therefore, in big angle speed maneuver process, adopt attitude quaternary element the most suitable.In big angle speed maneuver process, traditional attitude of flight vehicle measuring method is: application rate gyro to measure aircraft is found the solution the attitude parameter of aircraft then around the rotating speed of each by kinetics equation.Yet,, often can not satisfy the demand of current flight device high-precision attitude control so the attitude parameter of finding the solution certainly exists certain error because the attitude measurement system of gyro has slow drift.The present invention proposes a kind of and adopts the autonomous attitude method of star sensor, calculates the actual output of star sensor attitude according to the attitude of prediction.To satisfy the control requirement that the high precision of aircraft when the speed maneuver of big angle adopts no gyro.

The forecast model of derivation big angle speed maneuver clock star inconocenter

Traditional star track algorithm only makes full use of previous frame star sensor data and obtains the star of present frame as information.When aircraft is in the big angle speed maneuver, because same fixed star moves in the star chart of adjacent continuous frame on a large scale.Must scan the bigger zone of star chart at the star that obtains present frame as much as possible as coordinate time like this, thereby reduce the star sensor data updating rate; Simultaneously because the increase of chosen area, increased and comprised other star picture part pixel or whole possibility of pixels in regional, therefore increased the possibility of mistake coupling as coordinate time choosing correct star.The star track algorithm that adopts the inventive method proposition according to the desirable star inconocenter of previous frame prediction, serves as with reference to extracting actual star image position with these desirable star inconocenters before the extraction star is as coordinate.And the attitude information that utilizes prediction predict the known fixed star visual field at the desirable star of next frame as coordinate, these coordinates are as the Given information of star sensor extraction next frame star chart star as coordinate.The real-time and the reliability that only adopt star sensor to navigate when satisfying the speed maneuver of aircraft big angle.

Characteristics of the present invention and advantage are:

First:, independently predict the ideal pose of next frame according to the former frame output of star sensor attitude.

Second: extract star as need only searching for the subregion of star chart in the process, thereby avoided judging whether to exist the star picture in most of star chart background.

The the 3rd: verify unknown message according to Given information, thereby improved the reliability of the unknown fixed star information of obtaining.

(4) description of drawings

Fig. 1 is adjacent two moment star charts;

Fig. 2 is a big angle speed maneuver clock star track algorithm workflow diagram;

Fig. 3 is spherical co-ordinate and the desirable star synoptic diagram that concerns as coordinate;

Fig. 4 is the synoptic diagram that concerns of spherical triangle o ' s ' P;

Fig. 5 is the coordinate conversion synoptic diagram;

Fig. 6 is theory diagram under star sensor is operated in traditional star tracing mode;

Fig. 7 is operated in theory diagram under the dynamic star tracing mode of height for star sensor;

Fig. 8 is high dynamically star tracing mode theory diagram.

(5) embodiment

The present invention is further illustrated below in conjunction with the drawings and specific embodiments:

Star sensor system partly is made up of probe segment, data processor in the present embodiment.Wherein probe segment comprise light shield, optical lens, imageing sensor, support circuit and with interface of data processor etc.; Data processor comprises computing machine, storer and external interface etc.

In conjunction with Fig. 6 and Fig. 7, the star sensor principle of work is: fixed star is by the star sensor optical lens, be imaged on star sensor as (such as CCD or APS) on the plane, imaging circuit is converted into a complete star chart to the electric signal as fixed star in the plane, and is kept in the storer; Star picture extraction software reads the star chart data in the storer, and extracts star as coordinate from star chart; Importance in star map recognition software adopts whole day ball recognizer according to the star catalogue information that is kept in the star sensor, these stars is discerned as coordinate (if star sensor has prior imformation, importance in star map recognition software adopts traditional star track algorithm; The present invention program adopts high dynamically star tracing mode, and this also is the content that the present invention will protect, and sees Fig. 7); Attitude Calculation software adopts corresponding Attitude Calculation algorithm and recognition result, calculates current star sensor attitude information, and by external interface, sends to the aircraft navigation computing machine.

In conjunction with Fig. 8, the high dynamically star tracking method that present embodiment proposes is: the desirable star according to the prediction of star sensor previous frame extracts corresponding star as coordinate as coordinate information from the present frame star chart, then according to the star that extracts as coordinate Calculation present frame attitude, utilize present frame attitude result and previous frame attitude result to predict the next frame attitude information, at last according to the attitude information of prediction predict in the present frame visual field all known fixed stars in the next frame star chart corresponding desirable star as coordinate.Preserve the celestial coordinates of the desirable star of these predictions, extract the Given information of star as coordinate as star sensor next frame star chart as coordinate and corresponding star picture.

Star tracking method when the present invention is directed to the speed maneuver of star sensor big angle is studied.The star tracking method workflow is shown in Fig. 2 (detailed process of this method is as Fig. 7) under the speed maneuver of big angle.

Main research contents is as follows:

(1) the autonomous prediction of star sensor attitude during the speed maneuver of big angle

Make the plain q of being of attitude quaternary of initial time T1, next is T constantly ₁The attitude quaternary element of+Δ T is q ".Press the multiplication order and the multiplication rule of algebraically quaternary element, calculate the plain q ' of attitude maneuver quaternary between this two moment.

q′＝q ^-1q″ (1)

From the control loop angle, q ' also can be called the plain deviation of quaternary of the relative targeted attitude of present attitude.Again according to the plain q of quaternary " and the multiplication of attitude maneuver hypercomplex number q ' and algebraically quaternary element is in proper order and multiplication rule, T so ₁The plain q of the attitude quaternary of+2 Δ T " '.

q″′＝q′q″ (2)

Wherein: q=q ₁I+q ₂J+q ₃K+q ₄,

$q\&prime;={\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;}i+q_2^{\&prime;}j+q_3^{\&prime;}k+q_4^{\&prime;},$

$q\&prime;\&prime;={\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;\&prime;}i+q_2^{\&prime;\&prime;}j+q_3^{\&prime;\&prime;}k+q_4^{\&prime;\&prime;},$

$q\&prime;\&prime;\&prime;={\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;\&prime;\&prime;}i+q_2^{\&prime;\&prime;\&prime;}j+q_3^{\&prime;\&prime;\&prime;}k+q_4^{\&prime;\&prime;\&prime;}.$

The result can calculate T according to the prediction attitude ₁+ 2 Δ T constantly the optical axis of star sensor point to (A, D) and the roll angle θ of star sensor:

$\left.\begin{array}{c}A=\mathrm{arctg}\left(\frac{2*(q_2^{\&prime;\&prime;\&prime;}{q}_3^{\&prime;\&prime;\&prime;}-{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;\&prime;\&prime;}{q}_4^{\&prime;\&prime;\&prime;})}{2*({\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;\&prime;\&prime;}{q}_3^{\&prime;\&prime;\&prime;}+q_2^{\&prime;\&prime;\&prime;}{q}_4^{\&prime;\&prime;\&prime;})}\right)\\ D=\arcsin (-{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;\&prime;\&prime;}{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;\&prime;\&prime;}-q_2^{\&prime;\&prime;\&prime;}{q}_2^{\&prime;\&prime;\&prime;}+q_3^{\&prime;\&prime;\&prime;}{q}_3^{\&prime;\&prime;\&prime;}+q_4^{\&prime;\&prime;\&prime;}{q}_4^{\&prime;\&prime;\&prime;})\end{array}\right\}---\left(3\right)$

$\mathrm{\&theta;}=\mathrm{arctg}\left(\frac{-2({\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;\&prime;\&prime;}{q}_2^{\&prime;\&prime;\&prime;}-q_3^{\&prime;\&prime;\&prime;}{q}_4^{\&prime;\&prime;\&prime;})}{-{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;\&prime;\&prime;}{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="A200810209622E00131.png,A200810209622E00141.png"\; state="\{\{state\}\}">q</figure-callout>}}_1^{\&prime;\&prime;\&prime;}+q_2^{\&prime;\&prime;\&prime;}{q}_2^{\&prime;\&prime;\&prime;}-q_3^{\&prime;\&prime;\&prime;}{q}_3^{\&prime;\&prime;\&prime;}+q_4^{\&prime;\&prime;\&prime;}{q}_4^{\&prime;\&prime;\&prime;}}\right)---\left(4\right)$

Wherein A ∈ [0,2 π), D ∈ [pi/2, pi/2], θ ∈ [0,2 π).

In like manner, according to the result and the T of formula (1) and formula (2) ₁+ Δ T the moment and T ₁+ 2 Δ T attitude information constantly can be predicted T ₁+ 3 Δ T attitude information constantly.Successively repeatedly.

(2) in the star sensor visual field fixed star star as the prediction of coordinate

Star as the prediction of coordinate be exactly set up fixed star in star chart ideal coordinates (x, y) and the mathematical model of celestial coordinates (α, δ, i.e. right ascension and the declination of fixed star in celestial coordinate system).According to star sensor optical lens image-forming principle, can make as shown in the figure in the celestial sphere fixed star and the star in the star sensor star chart thereof as geometric relationship.In Fig. 3, o ₁And o ₂Represent the outer principal point and the interior principal point of camera object lens, from o ₂Make the vertical line of egative film and tell somebody what one's real intentions are sheet in the o point, this point is called the photocentre (being that the star sensor optical axis points to) of egative film.In ideal conditions, the o point should be positioned on the optical axis, and and the geometric center of egative film roughly overlap.

Pass through o ₁Draw o ₂The parallel lines of o hand over celestial sphere in o ', and the o point is exactly the projection image of o ' point on star chart; Certain fixed star s ' projection on star chart is to pass through o on the celestial sphere ₁Be parallel to o ₁The intersection point s of the straight line of s ' and star chart; The projection of declination circle o ' P on star chart of passing through o ' point is the straight line o ' P of ordering by o ₁

On star chart, be that initial point is set up a rectangular coordinate system (being the star chart photo coordinate system) with photocentre o; With oP ₁Be on the longitudinal axis (y axle), get direction that declination increases for just; To make transverse axis (x axle), get direction that right ascension increases for just by the o point straight line vertical with the y axle; The coordinate of Gou Chenging is that desirable star is as coordinate system like this.For a width of cloth star chart, desirable star is unique as coordinate system.Therefore the coordinate of fixed star in this coordinate system---desirable star as coordinate (x, y)---and celestial coordinates (α is one to one δ).

In Fig. 3, because triangle o ₂∠ o of so ₂Os=90 °, so:

os＝oo ₂tg∠oo ₂s＝ftgσ (5)

Wherein: f is a focal length, and σ is the angular distance of o ' s ', σ=∠ s ' o ₁O '=∠ oo ₂S.The desirable star of s as star picture element heart coordinate (x y) is:

$\left.\begin{array}{c}x=\mathrm{os}\sin \mathrm{\&omega;}=\mathrm{ftg\&sigma;}\sin \mathrm{\&omega;}\\ y=\mathrm{os}\cos \mathrm{\&omega;}=\mathrm{ftg\&sigma;}\cos \mathrm{\&omega;}\end{array}\right\}---\left(6\right)$

Make f=1, promptly represent ideal coordinates with radian, formula (6) can be expressed as:

$\left.\begin{array}{c}x=\mathrm{tg\&sigma;}\sin \mathrm{\&omega;}\\ y=\mathrm{tg\&sigma;}\cos \mathrm{\&omega;}\end{array}\right\}---\left(7\right)$

According to the relation of celestial coordinates, can get as described in Figure 4.

According to the sphere sine formula:

$\frac{\sin A}{\sin a}=\frac{\sin C}{\sin c}---\left(8\right)$

Can get

$\frac{\sin (\mathrm{\&alpha;}-A)}{\sin \mathrm{\&sigma;}}=\frac{\sin w}{\sin (90-\mathrm{\&delta;})}---\left(9\right)$

So sin σ sin w=cos δ sin (α-A) (10)

According to sphere five elements formula

sin a cos C＝cosc sin b-sin c cos b cos A (11)

Can get

sin σ cos w＝cos(90-δ)sin(90-D)-sin(90-δ)cos(90-D)cos(α-A) (12)

Promptly

sin σ cos w＝sin δ cos D-cos δ sin D cos(α-A) (13)

According to cosine formula of spherical triangle

cos a＝cos b cos c+cos b cos c cos A (14)

Can get

cos σ＝cos(90-D)cos(90-δ)+sin(90-D)sin(90-δ)cos(α-A) (15)

cos σ＝sin D sin δ+cos D cos δ cos(α-A) (16)

(10) formula obtains divided by (16) $\frac{\sin \mathrm{\&sigma;}\sin w}{\cos \mathrm{\&sigma;}}=\frac{\cos \mathrm{\&delta;}\sin (\mathrm{\&alpha;}-A)}{\sin D\sin \mathrm{\&delta;}+\cos D\cos \mathrm{\&delta;}\cos (\mathrm{\&alpha;}-A)}---\left(17\right)$

(13) formula obtains divided by (16) $\frac{\sin \mathrm{\&sigma;}\cos w}{\cos \mathrm{\&sigma;}}=\frac{\sin \mathrm{\&delta;}\cos D-\cos \mathrm{\&delta;}\sin D\cos (\mathrm{\&alpha;}-A)}{\sin D\sin \mathrm{\&delta;}+\cos D\cos \mathrm{\&delta;}\cos (\mathrm{\&alpha;}-A)}---\left(18\right)$

(7) substitution (17) and (18), can be tied to the formula of desirable star picture element heart coordinate the plane of delineation coordinate system from celestial coordinates:

$x=\frac{\cos \mathrm{\&delta;}\sin (\mathrm{\&alpha;}-A)}{\sin \mathrm{\&delta;}\sin D+\cos \mathrm{\&delta;}\cos D\cos (\mathrm{\&alpha;}-A)}$ (19)

$y=\frac{\sin \mathrm{\&delta;}\cos D-\cos \mathrm{\&delta;}\sin D\cos (\mathrm{\&alpha;}-A)}{\sin \mathrm{\&delta;}\sin D+\cos \mathrm{\&delta;}\cos D\cos (\mathrm{\&alpha;}-A)}$

Wherein (A is that ideal coordinates are the sensing of center (being that optical axis points to) in celestial coordinate system D).

If plane of delineation coordinate system can not be parallel fully with celestial coordinate system,, be tied to the formula (as Fig. 5) of desirable star picture element heart coordinate the plane of delineation coordinate system so from celestial coordinates according to the roll angle θ of star sensor:

x′＝xcosθ-ysinθ

(20)

y′＝xsinθ+ycosθ

Main performance index of the present invention:

The inventor has chosen the test figure of XX-9 satellite star sensor.In process of the test, choose certain continuous one group randomly.And from these group data, choose the two continuous frames data randomly as test sample.Test findings such as table 1, table 2 and table 3.

The attitude of table 1 prediction

	Hypercomplex number (q=q0*i+q1*j+q2*k+q3)
		T 1Constantly export attitude	(-0.4245132208，0.8266678452，-0.3633938730，-0.0659839511)
T 1+ Δ T exports attitude constantly	(-0.4404302537，0.8181902766，-0.3648420274，-0.0589610189)
		T 1+ 2 Δ T predict attitude constantly	(-0.4561814904，0.8094046981，-0.3661528373，-0.05191588910)
T 1+ 2 Δ T are actual attitude constantly	(-0.4572483897，0.8089197278，-0.3659644127，-0.0514080785)

Prediction coordinate (the unit: pixel) of known fixed star in table 2 visual field

T 1+ Δ T constantly star as coordinate (x, y)	T 1+ 2 Δ T predict constantly star as coordinate (x, y)	T 1+ 2 Δ T constantly actual star as coordinate (x, y)
			(511.18521118，214.42062377) (530.52551269，478.35275268) (591.88635253，350.47711181) (86.00104522，216.74656677) (513.08862304，362.81991577) (516.82531738，310.4861755)	(453.18865966，256.53280639) (494.26913452，208.90040588) (536.39508056，390.90789794) (28.10876846，265.98397827) (457.84274291，404.77670288) (460.61505126，352.35192871)	(452.99288601，256.74006545) (494.36827867，211.96361643) (533.21981901，386.706991669) (33.08039070，259.26346153) (455.41826862，398.85808387) (458.83270927，353.5594146)

Table 3 extracts star as coordinate time scanning pixel quantity

Method	Scanning pixel quantity (individual)
		The tradition star tracking method	264600
This method	2400

As

(this moment, aircraft three axis angular rates were respectively 0.96889788000451 °/s shown in the table result;-1.1801368599207 °/s; 1.6070238993998 °/s), same fixed star is at T ₁+ Δ T the moment and T ₁+ 2 Δ T star constantly has 100 pixels as coordinate distance.Therefore in order correctly to extract the fixed star star as coordinate, the radius R that must choose scanning star chart zone is at least 105.And the inventive method adopts the star of prediction fixed star earlier as coordinate, extracts corresponding actual star as coordinate again in the star of prediction as coordinate is the scope at center.Therefore extracting actual star as coordinate time, only need zone less in the scanning star chart (as shown in table 2, T ₁+ 2 Δ T predict that constantly star is as coordinate and T ₁+ 2 Δ T constantly actual star have only 5 pixels as coordinate distance, extract correct star as coordinate time, choose the radius R that scans the star chart zone less than 10 just can).As can be seen from Table 3, adopt this method only need scan 2400 pixels and just can correctly extract star as coordinate, and classic method need to scan 26400 pixels (be that this method is a 400 * n pixel, and classic method is a 4400 * n pixel.Wherein n is the quantity of known fixed star in the visual field).So the inventive method had both been inherited the advantage of traditional star track algorithm, overcome the shortcoming of traditional star track algorithm again.

Claims (4)

1, star tracking method under a kind of star sensor height is dynamic, it is characterized in that it may further comprise the steps: at first the desirable star according to the prediction of star sensor previous frame extracts corresponding star as coordinate as coordinate information from the present frame star chart, then according to the star that extracts as coordinate Calculation present frame attitude, utilize present frame attitude result and previous frame attitude result to predict the next frame attitude information, at last according to the attitude information of prediction predict in the present frame visual field all known fixed stars in the next frame star chart corresponding desirable star as coordinate, preserve the celestial coordinates of the desirable star of these predictions, extract the Given information of star as coordinate as star sensor next frame star chart as coordinate and corresponding star picture.

2, the high star tracking method under dynamically of a kind of star sensor according to claim 1, it is characterized in that described star sensor system partly is made up of probe segment, data processor, wherein probe segment comprise light shield, optical lens, imageing sensor, support circuit and with the interface of data processor, optical lens is arranged in the light shield, imageing sensor connects optical lens, support the circuit connection diagram image-position sensor, the interface of data processor is connection layout image-position sensor and data processor respectively; Data processor comprises computing machine, storer and the external interface that is connected probe segment, light signal in the celestial sphere at first passes through light shield, light shield passes through optical lens after eliminating the veiling glare of these light signals, be imaged in the imageing sensor of star sensor, imageing sensor is under the driven of supporting drives, light signal is converted to electric signal, form the correct star chart of a width of cloth, this star chart is kept in the storer of data processor part by interface with data processor, computing machine reads star chart information from storer, and this star chart handled, comprise and extract star as coordinate, importance in star map recognition, the Attitude Calculation process sends to the aircraft navigation computing machine to the information of calculating such as attitude result by external interface at last.

3, the high star tracking method under dynamically of a kind of star sensor according to claim 2, it is characterized in that described star tracking method is: fixed star is by the star sensor optical lens, be imaged on star sensor as on the plane, imaging circuit is converted into a complete star chart to the electric signal as fixed star in the plane, and is kept in the storer; Star picture extraction software reads the star chart data in the storer, and from the present frame star chart, extract star and be as coordinate: be to extract corresponding star as coordinate in the star chart among a small circle at center with the previous frame star as coordinate as the method for coordinate according to prior imformation correct star that extracts from the star chart appropriate area; Owing to comprised these known fixed star star pictures in celestial coordinates information in the prior imformation, so needn't look like to discern to these fixed star stars; Attitude Calculation software adopts corresponding Attitude Calculation algorithm, utilize star follow the tracks of to extract star as coordinate and prior imformation culminant star as celestial coordinates information, calculate current star sensor attitude information, and, send to the aircraft navigation computing machine by external interface.

4, the high star tracking method under dynamically of a kind of star sensor according to claim 3, it is characterized in that described star is high dynamically star tracing mode as the coordinate recognition methods, high dynamically star tracking method is: fixed star is imaged on star sensor as on the plane by optical lens, by related circuit electric signal is converted into a complete star chart, this star chart is exactly the star chart of star sensor present frame, extracts known fixed star star as coordinate method to be from the star chart of present frame: with the desirable star of previous frame prediction as coordinate S _i(i=1,2 ... n, wherein n is the quantity of known fixed star in the visual field, down together) be the center, be to extract the star of corresponding fixed star in star sensor present frame star chart as coordinate S in the round scope of radius with R _i' (i=1,2, ... n), because these star pictures have been known fixed stars at previous frame, therefore the celestial coordinates of these star picture correspondences is known in present frame, therefore needn't look like to discern again to these stars, the star that extracts according to present frame calculates the star sensor present frame as the celestial coordinates of coordinate and these star picture correspondences, it is the attitude information of current time, according to present frame star sensor attitude information and previous frame star sensor attitude information, the forecast model of star sensor attitude is predicted the attitude information of star sensor next frame when utilizing the big angle speed maneuver, star sensor attitude information and the coordinate of all known fixed stars of present frame under celestial coordinate system according to this prediction, utilize the forecast model of big angle speed maneuver clock star inconocenter to predict the ideal coordinates of all known fixed stars of present frame in star sensor next frame star chart, pass through external interface, calculating the star sensor present frame, the out of Memory such as attitude result that are current time send to the aircraft navigation computing machine, preserve the celestial coordinates of the desirable star of these predictions simultaneously, extract the Given information of star as coordinate as star sensor next frame star chart as coordinate and corresponding star picture.

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