CN102322849B - Pretreatment method of real-time transmission tasks - Google Patents

Abstract

The invention relates to a pretreatment method of real-time transmission tasks. First, time zones in which a ground target is visible to a satellite are calculated, and tasks when there is no visible time window or when the time window is in the earth shadow are rejected. Then, time zones in which a ground station and the satellite can communicate are determined, time zones in which real-time transmissions of the tasks can be carried out by the satellite are determined, and tasks without a real-time transmission zone are rejected. Factors influencing graph qualities are determined, imaging quality determination functions are established, and tasks which can not satisfy the imaging quality requirements are rejected. Clipping is carried out upon the real-time transmission zone of each left task, such that task execution time windows satisfying the imaging quality requirements are obtained. Meanwhile, according to the attitude angle of the satellite pointing at the target at each time point during a task execution procedure, the observation duration of the task is calculated. When the observation duration of the task is in the task execution time window, the task is considered as an executable task. All executable tasks are submitted to a satellite task planning system, and are subject to task planning and task scheduling.

Description

A kind of preprocess method to real biography task

Technical field

The invention belongs to satellite mission planning and scheduling field, relate in a kind of satellite mission planning process the preprocess method to the real-time Transmission task.

Background technology

The rapid attitude maneuver imaging satellite can be realized the Various Complex imaging pattern by the rapid attitude maneuver ability.Compare with the traditional earth observation satellite that adopts the substar imaging, the rapid attitude maneuver ability has increased the observation airplane meeting of satellite to target greatly, thereby has stronger observing capacity.Each imaging pattern of rapid attitude maneuver imaging satellite all is accompanied by the operations such as a plurality of attitude maneuvers, camera switch machine, and these operations form the steering order sequence that front and back link up.Because instruction is various, can't guarantee the reliability of instruction layout and upper notes and the real time problems that instruction is carried out, therefore must set up cover mission planning and a dispatching system, finish the automatic analysis ﹠ process of observation mission in enormous quantities.

Real biography task is a generic task more special in the satellite earth observation task, need to be at the same at present blit picture of imaging, and be the key link of rapid attitude maneuver imaging satellite mission planning to the pre-service of real biography task.Seldom mention the pre-service to real biography task in the existing mission planning method, and there is certain defect in the calculating at time window, such as Liu Xiong at the 23rd volume 7 phases " Computer Simulation " " exploitation of Pretreatment Module for Satellite Global Survey Mission Plan System " delivered in 2006, Li Xi is in its master's thesis " the efficiency optimization method research of many constellations territory observation mission ", and Li Jufang is in its doctor's thesis " many land stations of the many stars of space reconnaissance mission planning Study on Problems ", all mentioned and adopted STK software to calculate the method for visible time window, its basic step is constructive simulation scene in STK software, set up satellite, terrain object and sensor artificial physical, satellite orbit is set, the parameters such as sensor field of view can be by sensor and target data.This method realizes simple, in satellite mission planning method research and software product, be widely applied, but, carry out the task pre-service based on STK software, meeting is so that final optimum results is subject to the impact of STK software, the error of STK software also inevitably can be brought in the final optimum results, and this method do not consider different observation condition hypograph qualitative changes, degradation problem under the resolution of image when excessive such as satellite side-sway angle or the angle of pitch.

The rapid attitude maneuver imaging satellite is owing to possessing the Large Angle Attitude Maneuver ability, there is very big-difference in image quality when same section visible time interval adopts different attitude angle that same target is observed, so the method is inapplicable to the rapid attitude maneuver imaging satellite.In addition, in the task planning system, wish real biography task is carried out certain pre-service, eliminate its singularity, make it to adopt same treatment scheme with other tasks, to simplify procedures, and not needing the problems such as whether other consideration can pass in fact, prior art can't satisfy this class demand.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, a kind of preprocess method to real biography task of highly versatile is provided.

Technical solution of the present invention is: a kind of preprocess method to real biography task, and step is as follows:

(1) according to the camera fabric width mission area band is divided;

(2) determine that according to the maximum angle of pitch of satellite and maximum roll angle and taskbar information satellite is to the visible time interval [t of each band ₀', t _n'], reject the visible time window of nothing and time window in the task in shadow zone, ground; Visible time interval [the t of each band ₀', t _n'] by the visible time interval [t of satellite to these four summits of band ₁, t ₂] _k, k=1,2,3,4 seek common ground and reject behind the time interval in shadow zone, ground obtains; Satellite is determined by the maximum angle of pitch and the maximum roll angle of satellite the visible time interval on the single summit of band;

(3) according to ground station location and satellite orbit parameter, but the interval [t of the call duration time of calculating land station and satellite _D0, t _Dn];

(4) according to step (3) but the interval [t of the call duration time that obtains _D0, t _Dn] to visible time interval [t ' ₀, t ' _n] reduce, determine that satellite can carry out the real time interval [t that passes to task ₀, t _n], rejecting does not exist can pass interval task in fact;

(5) with modulation transfer function, the geometric resolution, signal to noise ratio (S/N ratio) and the fabric width that push away the geometric resolution of sweeping direction, linear array direction be as the principal element that affects picture quality, in step (4) but the interval [t of the call duration time of determining ₀, t _n] the interior function of a single variable R (t) that picture quality is expressed as the time,

R(t)＝η _MTFR _MTF+η _GSDxR _GSDx(t)+η _GSDyR _GSDy(t)+η _snrR _snr(t)+η _breathR _breath(t)，

η in the formula _MTF+ η _GSDx+ η _GSDy+ η _Snr+ η _Breath=1, R _MTF, R _GSDx(t), R _GSDy(t), R _Snr(t), R _Breath(t) be respectively modulation transfer function, the geometric resolution, signal to noise ratio (S/N ratio) and the fabric width that push away the geometric resolution of sweeping direction, linear array direction and the function of a single variable of time relation;

(6) the function of a single variable expression formula that adopts step (5) to obtain calculate respectively in step (4), determine can pass in fact time interval [t ₀, t _n] two end points t ₀And t _nAnd the highest moment point t of interval image quality _mPicture quality R ₀=R (t ₀), R _n=R (t _n), R _Max=R (t _m);

(7) the minimum license image quality of note is R _p, with R _pThe R that obtains with step (6) ₀, R _n, R _MaxCompare, set the tasks satisfy that image quality requires can pass in fact interval [t ₁, t ₂], reject and do not satisfy the task that image quality requires;

(8) adopt Secant Method to calculate the observation duration T of each task band _Last, T _LastFor the summit of observing at first from this band begins to finish duration to the summit of the last observation of this band; Observation duration T when the task band _LastDuring less than the task observation window time interval length of step (7), this task be for executing the task, and all can be executed the task submit to the mission planning system and carry out mission planning and scheduling.

The present invention's advantage compared with prior art is:

(1) but the present invention according to the call duration time of land station and satellite and user's image quality requirement, real biography task has been carried out preliminary screening, rejected " without visible time window ", " not satisfying image quality requires ", " time window is in the shadow zone, ground ", " do not exist and to pass in fact the interval ", " not satisfying the observation duration " of task, reached and cut down the decision-making quantity of mission planning problem and the purpose of feasible zone, reduced complication degree of problem, and eliminated the singularity of real biography task, made it to adopt same mission planning to process flow process with other tasks;

(2) in the task with traditional planning problem, all target is reduced to point target, sets unified, the less observation duration to guarantee to obtain the terrain object image of appointment; The rapid attitude maneuver imaging satellite is owing to possessing the Various Complex imaging pattern, there is very big-difference in the target sizes that faces, and attitude maneuver is frequent between the task, the time of expending is different, set the unified observation duration, will affect the rapid attitude maneuver imaging satellite and bring into play its dynamical advantage.The inventive method is according to the particular location of observed object, by determining the time of the corresponding substar of real biography task, obtain observation start time and the concluding time of task, calculate the more accurate observation duration, to satisfy the needs of rapid attitude maneuver imaging satellite mission planning;

(3) the present invention is with the foundation of image quality as time window calculating, the main dynamic indicator that affects picture quality is considered, for differently Table Properties and observation requirements, can be by adjusting the parameters such as weight, Reflectivity for Growing Season, different observed objects are treated with a certain discrimination, adapt to the cutting of different observed object time window and require diversified demand, can satisfy the needs of rapid attitude maneuver imaging satellite mission planning, and image quality computing function and the decoupling zero of time window method of cutting out have good versatility and dirigibility;

(4) the inventive method adopts Secant Method as finding the solution the observation duration of task and the core algorithm of minimum license image quality equation, not only can obtain the numerical solution of arbitrary accuracy, and iterations is less, computing velocity is fast, can satisfy Large-scale Optimization Problems for the constraint of algorithm time complexity.

Description of drawings

Fig. 1 is the FB(flow block) of the inventive method;

Fig. 2 is the visible time window calculation flow chart of the present invention;

Fig. 3 is fabric width formula proving schematic diagram of the present invention;

Fig. 4 is that task 2 can pass interval [t in fact in the embodiment of the invention ₀, t _n] the interior situation of change schematic diagram of observing the angle of pitch;

Fig. 5 is that task 2 can pass interval [t in fact in the embodiment of the invention ₀, t _n] the interior situation of change schematic diagram of observing roll angle;

Fig. 6 is that task 2 can pass interval [t in fact in the embodiment of the invention ₀, t _n] the situation of change schematic diagram of interior sun altitude;

Fig. 7 is that task 2 can pass interval [t in fact in the embodiment of the invention ₀, t _n] the situation of change schematic diagram of interior image quality.

Embodiment

As shown in Figure 1, the flow process of passing round for a look the preprocess method of survey task during rapid attitude maneuver imaging satellite of the present invention comprises: 1. the mission area band is divided; 2. the position of Calculation of Satellite and speed; 3. Calculation of Satellite is to the visible time interval of each task band; 4. but the call duration time that calculates land station and satellite is interval; 5. Calculation of Satellite can carry out the real time interval that passes to task; 6. the structure imaging quality is determined function; 7. judge the existence of time window; 8. adopt Secant Method cutting time window; 9. determine the observation duration; 10. output is to the pretreatment information of each real biography task.The below describes in detail respectively:

One, the mission area band is divided

Usually, the observation mission zone is described by the longitude and latitude on a plurality of summits, these summits is connected successively namely obtain mission area.Among the present invention, adopt following method mission area to be divided into the band that is parallel to satellite orbit, be convenient to satellite and implement observation:

1. from Satellite roll off the production line, as width, do the parallel lines that star rolls off the production line take substar camera fabric width (satellite side-sway angle as camera fabric width) at 0 o'clock, until cover mission area; It is the set of substar (the vertical projection point that satellite position point is gone up at the earth's surface;on the face of the globe) that star rolls off the production line;

2. do the vertical line that Satellite rolls off the production line from each summit of mission area, and calculate the distance between the intersection point, two the longest intersection points of distance are respectively L1 and L2 between the note intersection point, and the mission area summit corresponding with L1 is D1, and the mission area summit corresponding with L2 is D2;

3. connect respectively L1 and D1, L2 and D2 obtain and the roll off the production line intersection point of parallel lines of step 1 culminant star, consist of tetragonal 4 intersection points and namely form a task band, thus mission area are divided;

4. select to cover fully one or more task bands of mission area, as the elementary cell of mission planning and scheduling.

Two, the position of Calculation of Satellite and speed

Employing is to orbital position and the speed of satellite under the J2000 inertial coordinates system in the method forecast limiting time section of dynamics of orbits equation numerical value Integration Solving.

According to the orbital tracking of satellite, can extrapolate the orbital position R under the mission planning initial time J2000 inertial coordinates system _SatWith speed V _Sat, adopt again the Cowell method to find the solution dynamics of orbits equation (selecting Gauss perturbed motion equation), obtain the orbital position R of satellite under the J2000 inertial coordinates system in the limiting time section _SatWith speed V _SatGauss perturbed motion equation and Cowell method have detailed explanation in " spacecraft orbit is theoretical " (Liu Linzhu, 2000) book that National Defense Industry Press publishes.The J2000 inertial coordinates system defines the document that sees reference " Additional perturbation due to the change of coordinate system and reference frame are selected problem in the earth satellite motion " (" space science journal " the 2nd phase of the 28th volume in 2008, author Liu Lin, Tang Jingshi).

Three, Calculation of Satellite is to the visible time interval of each task band

To each band, the orbital position R that obtains according to above-mentioned second portion _SatWith speed V _SatCalculate the attitude angle that each discrete moment point satellite points to each band summit, according to attitude of satellite maneuvering range each discrete moment point is traveled through again, obtain the visible time window of each band, according to the result of calculation of target sun altitude, reject the observation window in the shadow zone, ground at last.The below describes with the example that is calculated as of a band.

1. according to the orbital position R under the J2000 coordinate system _SatWith speed V _Sat, calculate the attitude angle on each each summit of moment point satellite sensing band in the limiting time section.The below only describes with the example that is calculated as of a point.

The orbital position R of known satellite _Sat, speed V _Sat, the earth longitude and latitude of terrain object point

And Coordinated Universal Time(UTC) UTC time t.At first according to the earth longitude and latitude of impact point, calculate the constantly position vector R of impact point under the J2000 inertial coordinates system of t _{T, f}(t), then according to R _{T, f}(t) with satellite t position vector R constantly _Sat, obtain the attitude angle that t moment satellite points to this impact point.Concrete steps are as follows:

Terrain object is put the earth longitude and latitude be converted into the earth's core longitude and latitude Computing formula is:

λ _c＝λ _d，

Wherein

The expression compression of the earth, then calculate impact point the earth's core distance:

R _e=6378.140km is the terrestrial equator radius.

Be tied to the transition matrix R of J2000 inertial coordinates system according to UTC Time Calculation body-fixed coordinate system _If(t), computing method have a detailed description in " spacecraft orbit is theoretical " (Liu Linzhu, 2000) that National Defense Industry Press publishes.By coordinate transform, obtain the position vector of impact point under the J2000 inertial coordinates system:

R _x(α), R _y(α), R _z(α) represent respectively primitive transformation matrix around the rotation of x, y, z axle:

$R_x\left(\mathrm{\α}\right)=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos \mathrm{\α}& \sin \mathrm{\α}\\ 0& -\sin \mathrm{\α}& \cos \mathrm{\α}\end{array}\right]$

$R_y\left(\mathrm{\α}\right)=\left[\begin{array}{ccc}\cos \mathrm{\α}& 0& -\sin \mathrm{\α}\\ 0& 1& 0\\ \sin \mathrm{\α}& 0& \cos \mathrm{\α}\end{array}\right]$

$R_z\left(\mathrm{\α}\right)=\left[\begin{array}{ccc}\cos \mathrm{\α}& \sin \mathrm{\α}& 0\\ -\sin \mathrm{\α}& \cos \mathrm{\α}& 0\\ 0& 0& 1\end{array}\right]$

Then calculate the vector of satellite directed towards ground impact point under the J2000 inertial coordinates system:

R _f(t)＝R _T，f(t)-R _sat

With vector R _f(t) transform to the satellite orbit coordinate system by the J2000 inertial coordinates system:

$R_o\left(t\right)=R_{\mathrm{oi}}{R}_f\left(t\right)=\left(\begin{array}{c}{v}_x\left(t\right)\\ v_y\left(t\right)\\ v_z\left(t\right)\end{array}\right)$

Wherein, R _OiExpression J2000 inertial coordinate is tied to the transition matrix of satellite orbit coordinate system.Above-mentioned body-fixed coordinate system definition, satellite orbit Coordinate system definition and J2000 inertial coordinate are tied to the conversion derivation of satellite orbit coordinate system and see " satellite orbit and attitude dynamics and control " (Zhang Renwei writes, 1998) that publishing house of BJ University of Aeronautics ﹠ Astronautics publishes.

Crab angle is 0 o'clock, according to geometric relationship between the attitude Eulerian angle, obtains satellite to the observation attitude angle of target (turning order is 312):

$\left[\begin{array}{c}\mathrm{yaw}\left(t\right)\\ \mathrm{roll}\left(t\right)\\ \mathrm{pitch}\left(t\right)\end{array}\right]=\left[\begin{array}{c}0\\ \arcsin \left(\frac{v_x\left(t\right)}{\left|R_o\left(t\right)\right|}\right)\\ -\arctan \left(\frac{v_y\left(t\right)}{v_z\left(t\right)}\right)\end{array}\right]$

Yaw in the following formula (t), roll (t) and pitch (t) represent that respectively satellite points to the corresponding relation of time t and crab angle, roll angle and the angle of pitch in the attitude angle of impact point.

2. the targeted attitude angle of each moment point satellite that obtains according to attitude of satellite maneuvering range and step 1, Calculation of Satellite is to the visible time interval [t on each summit of band ₁, t ₂] _k, k=1,2,3,4.

Satellite is subject to the attitude maneuver ability of satellite to the observation of target, therefore only have in the attitude maneuver scope of the targeted attitude of satellite at satellite, could carry out observation mission.For k summit,

T represents the time range that limits, if corresponding attitude angle [yaw roll pitch] satisfies | and roll|≤roll _Max, | pitch|≤pitch _Max, roll wherein _Max, pitch _MaxThe maximum roll angle of expression satellite and the maximum angle of pitch, then t ∈ [t ₁, t ₂] _k, i.e. [t ₁, t ₂] _kFor the set of the t that satisfies above-mentioned condition, if [t ₁, t ₂] _kNot existing, is " without visible time window " with this target label.Calculation process as shown in Figure 2.

3. according to the visible time interval [t of satellite to each summit of band ₁, t ₂] _k, k=1,2,3,4, Calculation of Satellite to the visible time interval of band [t ' ₀, t ' _n].

To the visible time interval [t of satellite to each summit ₁, t ₂] _k, k=1,2,3,4 seek common ground, namely obtain satellite to the visible time interval of band [t ' ₀, t ' _n].

4. according to ground sun altitude result of calculation, reject the time interval in the shadow zone, ground.

Between the visible range that generally step 3 calculates [t ' ₀, t ' _n] have a plurality of solutions, wherein between the part visible range in the shadow zone, ground, can't satisfy the image-forming condition of optical camera, should give rejecting.

Between the visible range that step 3 is obtained [t ' ₀, t ' _n], a bit calculate the sun altitude ε of this moment point observed object from wherein optional, if ε＜0, then this is rejected in the shadow zone, ground, otherwise keeps.If there is no [t ' ₀, t ' _n] not in the shadow zone, ground, then with this target label be " time window is in the shadow zone, ground ".

Sun altitude is relevant with the time, and computation process is as follows:

(1) calculates Julian date and Julian century number according to the Gregorian calendar time (Pascal Greggory is gone through)

Be respectively Y, M, D if provide the year, month, day (containing the purpose fraction part) of Gregorian calendar time, then corresponding Julian date is:

$\mathrm{JD}=D-32075+[1461\×(Y+4800+[\frac{M-14}{12}\left]\right)\÷4]$

$+[367\×(M-2-[\frac{M-14}{12}]\×12)\÷12]$

$-[3\×[(Y+4900+[\frac{M-14}{12}\left]\right)\÷100]\÷4]-0.5$

The integral part that X is got in [X] expression in the formula, fraction part is omitted.

The yojan Julian date of starting at from 12 o'clock on the 1st January of nineteen fifty is MJD=JD-2433283

Revising the Julian century number is MJC=MJD/36525

(2) calculate the sun with respect to the variation of the orbit parameter of the earth

Major semi-axis a _h=1.49597927 * 10 ⁸

Eccentric ratio e _h=1.67301085 * 10 ^-2-4.1926 * 10 ^-5MJC-1.26 * 10 ^-7MJC ²

Orbit inclination (being ecliptic obliquity)

i _h＝23.4457888616-1.30141669×10 ^-2MJC-9.445×10 ^-7MJC ²+5.000×10 ^-7MJC ³；

Argument of perigee ω _h=1.67301085 * 10 ^-2-4.1926 * 10 ^-5MJC-1.26 * 10 ^-7MJC ²

Mean anomaly

M _h＝358.000682-0.9856002623MJD-1.550000×10 ^-4MJC ²-3.3333×10 ^-6MJC ³；

Right ascension of ascending node Ω _h=0;

(3) adopt solution by iterative method equation E _h-e _hSinE _h=M _h, obtain eccentric anomaly E _h, iterative formula is E _{H (k+1)}=e _hSinE _{H (k)}+ M _hOr

Initial value E _{H (0)}=M _h

(4) by E _hAnd e _hThe anomaly of looking for the truth θ _h

$\mathrm{tg}\frac{{\mathrm{\&theta;}}_{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">h</figure-callout>}}}{2}=\sqrt{\frac{1-{\mathrm{<figure-callout\; id="1"\; label="e\; h"\; filenames="HSA00000498678500021.png,HSA00000498678500033.png"\; state="\{\{state\}\}">e</figure-callout>}}_h}{1+e_h}}\mathrm{<figure-callout\; id="2"\; label="tg\; E\; h"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">tg</figure-callout>}\frac{E_h}{}\frac{{}_{}}{2};$

(5) according to formula u _h=ω _h+ θ _hCalculate latitude argument (being ecliptic longitude);

(6) according to formula tg α _h=cosi _hTgu _hCalculate sun right ascension α _h

(7) according to formula sin δ _h=sini _hSinu _hCalculate solar declination;

(8) according to formula α _G=α _G0+ 6.3003881t calculates the Greenwich right ascension;

(9) α _G0And α _GTake radian (rad) as unit, the time of t for starting at from the initial moment in this year (by universal time), take mean solar day as unit.α _G0Value is from finding the astronomical chronicle then;

(10) calculate the terrain object sun altitude

λ,

Be the observed object longitude and latitude.

The derivation of said method sees " spacecraft flight principle of dynamics " (Xiao Yelun writes, nineteen ninety-five) that the Yuhang Publishing House publishes for details.

Four, but the call duration time of Calculation of Satellite and appointment land station is interval

This part calculating can be finished by business softwares such as STK, and concrete steps are geographical longitudes and latitudes of input Coordinated Universal Time(UTC) UTC time t, satellite orbit parameter and land station in STK

Then set the antenna reception elevation angle EA of land station, but can obtain the interval [t of call duration time of satellite and land station _Gs1, t _Gs2].

Five, Calculation of Satellite can carry out the real time interval that passes to task

The satellite that obtains according to third part is to the visible time window [t of target ₀', t _n'] but and the interval [t of the 4th the part satellite that obtains and the call duration time of specifying land station _Gs1, t _Gs2], calculate satellite and can carry out simultaneously imaging and the time interval [t that passes down to task ₀, t _n], concrete steps are as follows:

(1) if t ₀'＜t _Gs1＜t _Gs2＜t _n', t then ₀=t _Gs1, t _n=t _Gs2

(2) if t _Gs1＜t ₀'＜t _n'＜t _Gs2, t then ₀=t ₀', t _n=t _n';

(3) if t _Gs1＜t ₀'＜t _Gs2＜t _n', t then ₀=t ₀', t _n=t _Gs2

(4) if t ₀'＜t _Gs1＜t _n'＜t _Gs2, t then ₀=t _Gs1, t _n=t _n';

(5) if t ₀'＜t _n'＜t _Gs1＜t _Gs2, [t then ₀, t _n] do not exist, namely do not exist and can carry out simultaneously imaging and the time interval that passes down, be " do not exist and can pass in fact the interval " with task flagging.

Six, the structure imaging quality is determined function

Image quality mainly determines by pushing away to sweep with parameters such as the geometric resolution of linear array both direction, modulation transfer function, signal to noise ratio (S/N ratio), fabric widths.Wherein the static factor such as the main and camera design manufacturing of MTF and satellite attitude stabilization degree, flutter etc. are relevant, and therefore the selection for observation time point does not have actual impact, are normal value when the setting of camera imaging parameter remains unchanged.Mainly by terrain object reflectivity and sun altitude decision, for the appointed area, reflectivity is certain to signal to noise ratio (S/N ratio), and sun altitude is larger, and signal to noise ratio (S/N ratio) is higher; Under the prerequisite that camera design parameter and satellite orbital altitude are determined, fabric width is relevant with the angle of pitch with the observation roll angle, and roll angle and the angle of pitch are larger, and fabric width is larger, because there is contradiction in large fabric width with high resolving power, so fabric width is not as the leading indicator of image quality calculating.Push away and sweep resolution and affected by the angle of pitch, the angle of pitch is larger, pushes away that to sweep resolution poorer.Linear array resolution is affected by roll angle mainly, and roll angle is larger, and linear array resolution is poorer.Therefore the dynamic factor that affects image quality mainly comprises roll angle, the angle of pitch and sun altitude.According to the content of third part, under the prerequisite that satellite, target are determined, observation time is unique determinative of roll angle, the angle of pitch and sun altitude, so image quality can be expressed as the function of a single variable of time.

Among the present invention, the image quality Comprehensive Assessment by MTF, push away geometric resolution, signal to noise ratio (S/N ratio) (snr) and fabric width (breath) weighted sum of sweeping direction (GSDx) and linear array direction (GSDy) and obtain.At first calculate respectively indices according to image-forming condition, then the result of calculation of indices is converted into the image quality of single index, again with indices.Weighting obtains the Comprehensive Assessment result.Computation process is as follows:

1. computational geometry resolution

Known satellite orbit altitude H, attitude angle [yaw roll pitch], camera pixel dimension d, focal distance f, field angle FOV, earth radius Re, satellite pushes away sweeps geometry of direction resolution GSD _xWith linear array geometry of direction resolution GSD _yFor

${\mathrm{GSD}}_x=H\&CenterDot;\sec \mathrm{\&beta;}\&CenterDot;\frac{\mathrm{<figure-callout\; id="2"\; label="d\; f\; sec"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">d</figure-callout>}}{f}{\sec }^{}{}^2\mathrm{\&gamma;}$

${\mathrm{GSD}}_y=H\&CenterDot;\mathrm{se}{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">c</figure-callout>}}^2\mathrm{\&beta;}\&CenterDot;\frac{d}{f}\sec \mathrm{\&gamma;}$

Wherein

Expression with the camera shooting spot projection to pushing away equivalent side-sway angle and the equivalent angle of pitch of sweeping after direction and the linear array direction.

2. be calculated to be film size wide

The fabric width computing method as shown in Figure 3, O represents the earth centre of sphere among the figure, S represents satellite, S ' expression substar ,+X represents the working direction of satellite, namely camera pushes away and sweeps direction, + Y represents camera linear array direction, supposes that the earth is desirable spheroid, and XY crosses on the plane substar and earth sphere is tangent.The intersection points on A, B 2 expressions viewing field of camera corner edge and XY plane, A ', B ' expression viewing field of camera corner edge and earth surface intersection point, then the spherical distance of A ', B ' point-to-point transmission is the fabric width of the attitude of satellite after motor-driven.The F point is the intersection point on camera optical axis and XY plane, and F ' is the intersection point of camera optical axis and earth surface.

It is α that note satellite optical axis points to the angle, and the attitude maneuver that A, B are ordered points to the angle and is respectively α ₁, α ₂, the character according to right-angle triangle has

$\mathrm{\&alpha;}=\arctan \left(\frac{\sqrt{{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{roll}+{\tan }^2\mathrm{pitch}}}{\cos \mathrm{roll}}\right)$

${\mathrm{\&alpha;}}_1=\arctan \left(\frac{\sqrt{{\sin }^2(\mathrm{roll}-\frac{\mathrm{FOV}}{2})+{\tan }^2\mathrm{pitch}}}{\cos (\mathrm{rpll}-\frac{\mathrm{FOV}}{2})}\right)$

${\mathrm{\&alpha;}}_2=\arctan \left(\frac{\sqrt{{\sin }^2(\mathrm{roll}+\frac{\mathrm{FOV}}{2})+{\tan }^2\mathrm{pitch}}}{\cos (\mathrm{rpll}+\frac{\mathrm{FOV}}{2})}\right)$

According to the triangulo operation relation, in triangle SOF ', can obtain:

So have

${\mathrm{SF}}^{\&prime;}=(R_e+H)\cos \mathrm{\&alpha;}-\sqrt{{R_e}^2-{(R_e+H)}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&alpha;}}$

In like manner can get

${\mathrm{SA}}^{\&prime;}=(R_e+H)\cos {\mathrm{\&alpha;}}_1-\sqrt{{R_e}^2-{(R_e+H)}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2{\mathrm{\&alpha;}}_1}$

${\mathrm{SB}}^{\&prime;}=(R_e+H)\cos {\mathrm{\&alpha;}}_2-\sqrt{{R_e}^2-{(R_e+H)}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2{\mathrm{\&alpha;}}_2}$

∠ A ' SB '=∠ ASB=FOV as shown in Figure 3, calculate the length of line segment A ' B ' in the middle employing cosine law of triangle A ' SB ':

$A^{\&prime;}{B}^{\&prime;}=\sqrt{{\mathrm{SA}}^{\&prime;2}+{\mathrm{SB}}^{\&prime;2}-{2\mathrm{SA}}^{\&prime;}\&CenterDot;{\mathrm{SB}}^{\&prime;}\&CenterDot;\cos \mathrm{FOV}}$

By geocentric angle corresponding to the length computation of line segment A ' B '

$\mathrm{\&phi;}=2\arcsin \left(\frac{A^{\&prime;}{B}^{\&prime;}}{{2R}_e}\right)$

Fabric width is the spherical distance L of A ', B ' point-to-point transmission _{A ' B '}=φ R _e

3. calculating signal to noise ratio (S/N ratio)

After CCD camera TDI integration progression was selected, signal to noise ratio (S/N ratio) was determined by sun altitude and Reflectivity for Growing Season.Signal to noise ratio (S/N ratio) is counted table under the snr computation employing structure different condition, and table of logarithm carries out the method for bivariate interpolation again.The structure that signal to noise ratio (S/N ratio) is counted table adopts 6S (Second Simulation of the Satellite Signal in the Solar Spectrum) software to calculate, and " analysis of HJ-1A Satellite CCD Camera incident light spectrum radiance " that Sun Jifu, Wu Yanlin deliver the 2nd phase of the 24th volume in 2003 " space flight is returned and remote sensing " has more specific introduction to the method.By 6S software, obtaining sun altitude is 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, 70 °, 80 °, 90 °, Reflectivity for Growing Season is 7%, 10%, 15%, 20%, 26%, 40%, 50%, 60%, 70%, 80%, 90%, signal to noise ratio (S/N ratio) corresponding to difference in the time of 100%, adopt on this basis the binary function interpolation calculation to obtain any sun altitude and any signal to noise ratio (S/N ratio) corresponding to Reflectivity for Growing Season, (Yan Qingjin writes in " numerical analysis " that the binary function interpolation is published in publishing house of BJ University of Aeronautics ﹠ Astronautics, 2000) detailed explanation is arranged in the book, method is as follows:

Known signal to noise ratio (S/N ratio) is counted table snr (r _i, ε _j), i=0,1 ..., 11, r _i=0.07,0.15 ..., 1.00, the expression Reflectivity for Growing Season, j=0,1 ..., 8, ε _j=10,20 ..., 90, the expression sun altitude.If Reflectivity for Growing Season and sun altitude (r, ε) satisfy arbitrarily:

r _i-1≤r＜r _i，ε _j-1≤ε＜ε _j

Then corresponding snr computation formula is:

$\mathrm{snr}(r,\mathrm{\&epsiv;})=\frac{(r-r_i)(\mathrm{\&epsiv;}-{\mathrm{\&epsiv;}}_j)}{(r_{i-1}-r_i)({\mathrm{\&epsiv;}}_{j-1}-{\mathrm{\&epsiv;}}_j)}\mathrm{snr}(r_{i-1},{\mathrm{\&epsiv;}}_{j-1})+\frac{(r-r_i)(\mathrm{\&epsiv;}-{\mathrm{\&epsiv;}}_{j-1})}{(r_{i-1}-r_i)({\mathrm{\&epsiv;}}_j-{\mathrm{\&epsiv;}}_{j-1})}\mathrm{snr}(r_{i-1},{\mathrm{\&epsiv;}}_j)$

$+\frac{(r-r_{i-1})(\mathrm{\&epsiv;}-{\mathrm{\&epsiv;}}_j)}{(r_i-r_{i-1})({\mathrm{\&epsiv;}}_{j-1}-{\mathrm{\&epsiv;}}_j)}\mathrm{snr}(r_i,{\mathrm{\&epsiv;}}_{j-1})+\frac{(r-r_{i-1})(\mathrm{\&epsiv;}-{\mathrm{\&epsiv;}}_{j-1})}{(r_i-r_{i-1})({\mathrm{\&epsiv;}}_j-{\mathrm{\&epsiv;}}_{j-1})}\mathrm{snr}(r_i,{\mathrm{\&epsiv;}}_j)$

Reflectivity for Growing Season is determined by morphologic characteristics in the above-mentioned algorithm, and for specific objective, Reflectivity for Growing Season is normal value.

4. calculate indices individual event quality grade

Calculate the individual event quality grade according to indices, wherein MTF, geometric resolution and fabric width adopt the method for linear interpolation to calculate, and signal to noise ratio (S/N ratio) is with reference to calculating with standard image-forming condition (70 ° of sun altitudes, Reflectivity for Growing Season 26%, 85 minute).

$R_{\mathrm{MTF}}=\frac{\mathrm{MTF}-{\mathrm{MTF}}_{\mathrm{worst}}}{{\mathrm{MTF}}_{\mathrm{best}}-{\mathrm{MTF}}_{\mathrm{worst}}}\&CenterDot;100$

Wherein, MTF _Worst, MTF _BestRespectively expression minimum, maximum MTF.

$R_{\mathrm{GSD}}=\frac{\mathrm{GSD}-{\mathrm{GSD}}_{\mathrm{worst}}}{{\mathrm{GSD}}_{\mathrm{best}}-{\mathrm{GSD}}_{\mathrm{worst}}}\&CenterDot;100$

GSD _Worst, GSD _BestRepresent respectively the poorest, best resolution.

$R_{\mathrm{breath}}=\frac{L-L_{\mathrm{worst}}}{L_{\mathrm{best}}-L_{\mathrm{worst}}}\&CenterDot;100$

L _Worst, L _BestRespectively expression minimum, maximum fabric width.

$R_{\mathrm{snr}}=\left\{\begin{array}{cc}85+\frac{\mathrm{snr}(r,\mathrm{\&epsiv;})-\mathrm{snr}\left(\mathrm{0.26,70}\right)}{\mathrm{snr}\left(\mathrm{1.00,90}\right)-\mathrm{snr}\left(\mathrm{0.07,10}\right)}\&CenterDot;15,& \mathrm{snr}(r,\mathrm{\&epsiv;})>85\\ \frac{\mathrm{snr}(r,\mathrm{\&epsiv;})-\mathrm{snr}\left(\mathrm{0.07,10}\right)}{\mathrm{snr}\left(\mathrm{1.00,90}\right)-\mathrm{snr}\left(\mathrm{0.07,10}\right)}\&CenterDot;15,& \mathrm{snr}(r,\mathrm{\&epsiv;})\&le;85\end{array}\right.$

5. be calculated to be the image quality integrated level

Image quality grade R=R (t) expression formula is as follows:

R (t)=∑ η _iR _i(t)=η _MTFR _MTF+ η _GSDxR _GSDx(t)+η _GSDyR _GSDy(t)+η _SnrR _Snr(t)+η _BreathR _Breath(t) η _MTF, η _GSDx, η _GSDy, η _SnrAnd η _BreathThe weight that represents respectively single index, the weight of single index satisfies ∑ η=1.Different according to user's request, the weight of indices can be adjusted.Comprehensive grading is the weighted sum of indices mark.Except MTF was normal value, other index scoring was the function of time.

Seven, judge the existence of time window

The function of a single variable expression formula R=R (t) that adopts the 6th part to obtain calculates respectively what step 5 was determined can pass time interval [t in fact ₀, t _n] two end points t ₀And t _nAnd the highest moment point t of image quality _mPicture quality R ₀=R (t ₀), R _n=R (t _n), R _Max=R (t _m).Remember that minimum license image quality is R _p, with R _pWith R ₀, R _n, R _MaxCompare, image quality requires can pass in fact interval [t for satisfying of setting the tasks ₁, t ₂] whether exist.

During the optical satellite imaging, usually adopt the substar image quality best, so R _MaxApproximate the high imaging quality grade of this visible time interval, at [t ₀, t _m] interval, R=R (t) can be approximately monotonically increasing function, at [t _m, t _n] interval, R=R (t) can be approximately monotonic decreasing function.

(1) if R _Max＜R _p, by the monotonicity of function as can be known, time interval [t then ₁, t ₂] do not exist, task flagging is " not satisfying image quality requires ";

(2) if R _Max＞R _p, R ₀〉=R _p, R _n〉=R _p, by the monotonicity of function as can be known, visible time interval satisfies image quality requirement, t fully ₁=t ₀, t ₂=t _n

(3) if R _Max＞R _p, R ₀＜R _p, R _n〉=R _p, by the monotonicity of continuous function intermediate value theorem and function as can be known, t ₁∈ (t ₀, t _m), t ₂=t _n, adopt Secant Method to ask t ₁

(4) if R _Max＞R _p, R ₀〉=R _p, R _n＜R _p, by the monotonicity of continuous function intermediate value theorem and function as can be known, t ₁=t ₀, t ₂∈ (t _m, t _n), adopt Secant Method to ask t ₂

(5) if R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), adopt Secant Method to ask t ₁, t ₂

Eight, adopt Secant Method cutting time window

According to minimum license image quality R _p, can pass in fact interval [t what satisfy that image quality requires ₁, t ₂] the interior Secant Method solving equation R that adopts _p=R (t _p), obtain the time window starting point t in the 7th part steps (3), (5) ₁, the time window end point t in step (4), (5) ₂

Secant Method (also claiming secant method) is to find the solution complex nonlinear equation a kind of numerical solution commonly used, and its advantage is that speed of convergence is very fast, and the rank of speed of convergence are at least 1.618, and has avoided Newton method to need the deficiency of computing function derivative.

Secant Method solving equation R _p=R (t _p) step as follows:

As [R (t ₀)-R (t _p)] [R (t _m)-R (t _p)]＜0 o'clock, And satisfy R _p=R (t _p).Make x _-1=t ₀, x ₀=t _m, for k=0,1 ..., M carries out

(1) calculates $x_{k+1}=x_k-\frac{R\left(x_k\right)\&CenterDot;(x_k-x_{k-1})}{R\left(x_k\right)-R\left(x_{k-1}\right)};$

(2) if | x _K+1-x _k|＜σ, get t _p≈ x _K+1, obtain the time window starting point, otherwise turn (1).Wherein M represents maximum iteration time, and σ is the error of calculation of license.

Make x _-1=t _m, x ₀=t _n, can obtain R with method _p=R (t _p) at interval (t _m, t _n) on another root, i.e. time window end point.

Nine, calculate the observation duration of target

The observation duration of band, namely from beginning to observe the duration that finishes observation, depend on the length of band.To a multi-ribbon task, because therefore the equal in length of all bands only needs an optional band to calculate, can obtain the observation duration of all bands.To each band, the satellite that at first obtains according to the step 1 of third part points to the attitude angle on each summit, adopt again Secant Method to calculate beginning observation time and the end observation time of band, obtain the observation duration of band, judge at last whether the visible time window of band can comprise the observation duration of band, if can not, then this task can not be carried out.The below describes as an example of a band example:

1. each the moment point satellite that obtains according to the step 1 of third part points to the attitude angle on each summit of band, [the t that obtains in the step 2 of third part ₁, t ₂] _k, k=1, in 2,3,4, adopting Secant Method to calculate the angle of pitch is 0 o'clock, satellite points to the time on each summit of band.

The below illustrates and adopts Secant Method solving equation Pitch (t take summit k as example _PkThe step of)=0:

Satellite determines visible time of target attitude maneuver ability by satellite, and satellite is changed to 0 to the observation angle of pitch of fixed target by positive maximal value in the rail motion process, become negative maximal value by 0 again, also namely at the visible time interval [t of summit k ₁, t ₂] _kOn, satellite is at first t ₁The angle of pitch be roll _Max, 1 t in the end ₂The angle of pitch be-roll _Max, therefore interval [t ₁, t ₂] _kIn the satellite angle of pitch must be arranged is 0 moment point, namely as Pitch (t ₁) Pitch (t ₂)＜0 o'clock,

And satisfy Pitch (t _Pk)=0.

Make x _-1=t ₁, x ₀=t _Pk, for i=0,1 ..., M carries out

(1) calculates $x_{i+1}=x_i-\frac{\mathrm{Pitch}\left(x_i\right)\&CenterDot;(x_i-x_{i-1})}{\mathrm{Pitch}\left(x_i\right)-\mathrm{Pitch}\left(x_{i-1}\right)};$

(2) if | x _I+1-x _i|＜σ, get t _Pk≈ x _I+1, obtaining the angle of pitch is 0 o'clock, satellite points to the time of representative points, otherwise turns (1).

Wherein M represents maximum iteration time, and σ is the error of calculation of license.

2. because satellite must start from certain summit to the observation of band, also end at certain summit, therefore according to the visible time of satellite to each summit, can determine satellite to the beginning observation time of band and finish observation time.

With t _PkAccording to the sequencing ordering, the note time the earliest is T _Start, the time the latest is T _End, represent respectively the beginning observation time of band and finish observation time.

3. calculate the lasting observation time of band according to following formula

T _last＝T _end-T _start

T _LastBe that visible time interval according to each summit of band calculates, consider the impact of ground shadow, therefore also need to judge and rejected behind the time interval in shadow zone, ground, satisfy the interval [t that image quality requires and can pass in fact what the 8th part obtained ₁, t ₂] whether can finish the observation to band:

If T _Last＞t ₂-t ₁, it is shorter than the observation duration that this band satisfies the visible time window of all requirements, and whole observation mission can't be finished.

Ten, export the time window information of all targets, for being labeled of task, the reason that output can not be finished to the mission planning system, is carried out mission planning and scheduling with the job invocation that is not labeled.

Embodiment

Consider a rapid attitude maneuver imaging satellite that runs on the sun synchronization circular orbit, epoch, 00:00:00.000 on July 26th, 2009 (universal time coordinated UTC) wink radical was semi-major axis 7051.2km constantly, 97.3087 ° of orbit inclinations, 249.784 ° of right ascension of ascending node, 0 ° of latitude argument.Reflectivity for Growing Season 50%.Attitude of satellite maneuvering range is pitch orientation and rotating direction ± 45 °.Under to pass bit rate be 800Mbps.The geographical latitude and longitude information of target is as shown in table 1, and all observed objects in this example are point target.

The geographical longitude and latitude of table 1 target

Task number	Geographic longitude (°)	Geographic latitude (°)	Minimum license image quality R p
				1	61.1834	37.5404	70
2	130.9340	59.6211	70
				3	114.5653	-3.1025	70
4	121.5680	44.2996	70
				5	122.6877	41.2745	70
6	96.2793	36.6533	70

The geographical latitude and longitude information of available land station is as shown in table 2, and antenna reception elevation angle EA is 10 °.

Table 2 can be used the geographical longitude and latitude of land station

Land station's title	Geographic longitude (°)	Geographic latitude (°)
			Beijing	116.388	39.9062
Kunming	102.7021	25.051

The satellite optical camera adopts panchromatic and multispectral two kinds of CCD, panchromatic pixel dimension 10 μ m, and multispectral pixel dimension 40 μ m, camera focus 10m, 1.07 ° of field angle, MTF is 0.0902 to the maximum, and minimum 0.0818.Panchromatic CCD TDI integration progression is set at 24 o'clock, and MTF is 0.0895.It is as follows that signal to noise ratio (S/N ratio) is counted table:

Adopt the inventive method as follows to the pre-treatment step of these real biography tasks:

(1) the mission area band is divided

Because all observed objects in this example are point target, therefore need not carry out band and divide.

(2) the visible time window of calculation task

According to orbit elements of satellite, calculate orbital position, the speed of satellite under the J2000 coordinate system in the universal time coordinated UTC 00:00:00.000 on July 27,00:00:00.000 to 2009 year on the 26th July in 2009, then calculate each whole second moment satellite to the observation angle of task.According to attitude of satellite maneuvering range, obtain its visibility window of satellite and task.The observation angle of task 1 has exceeded the maximum attitude maneuver scope of satellite, so task 1 is marked as " without visible time window ", and the result of calculation of other tasks is as shown in table 3.

The visible time window of table 3 task

Task number	As seen the zero hour t ' 0	As seen the finish time t ' n
			2	00:30:55	00:34:25
3	00:48:11	00:51:32

4	00:35:22	00:38:44
			5	00:36:04	00:39:32
6	02:15:31	02:18:58

Except task 1 " without visible time window ", all the other tasks all are in sun according to the district.

(3) but calculate the call duration time of land station and satellite

According to ground station location and satellite orbit parameter, but the interval [t of the call duration time of calculating land station and satellite _D0, t _Dn].Generally, but there are a plurality of communication intervals in each land station and satellite, and result of calculation is as shown in table 4.

But the call duration time of table 4 target and satellite

(4) calculation task can pass time interval in fact

According to step (3) but the satellite that obtains and the communication interval [t of land station _D0, t _Dn] to visible time interval [t ' ₀, t ' _n] reduce, determine that satellite can carry out the real time interval [t that passes to each task ₀, t _n], result of calculation is as shown in table 5.

Table 5 target can pass the interval in fact

Task 2～task 6 all exists can pass the interval in fact, and task 4～task 6 and two land stations all exist and can pass in fact the interval.

(5) be specified to the major influence factors of image quality

Because the selection of MTF and observation time point is irrelevant, not the principal element that affects image quality therefore;

Can pass in fact between the time window 00:31:37 to 00:34:25 in task 2, the angle of pitch and roll angle result of calculation such as Fig. 4, shown in Figure 5, angle of pitch variation range is 31.7 °～-45 °, the roll angle variation range is 0.4 °～3.4 °, so angle of pitch variation is the principal element that affects image quality.Signal to noise ratio (S/N ratio) determines by sun altitude, sun altitude result of calculation as shown in Figure 6, in whole its visibility window, the variation range of sun altitude is no more than 1 °, is not the principal element that affects image quality therefore.

The analysis result of task 3～task 6 is identical with task 2.

(6) be calculated to be image quality

Because observation attitude angle and sun altitude all can be expressed as the function of a single variable of time, so image quality also can be expressed as the function of a single variable R (t) of time.

Because there are contradiction in large fabric width and high resolving power, when guaranteeing high resolving power by the restriction attitude angle, fabric width is reduced.Be generally image quality determine method with high resolving power as a prior index.In the present embodiment the weight of fabric width in image quality is made as 0, namely do not consider.

The weight allocation of indices is as follows:

Index	Weight
		MTF	0.125
Signal to noise ratio (S/N ratio)	0.375
		Panchromatic pushing away swept directional resolution	0.125
Panchromatic linear array directional resolution	0.125
		Multispectral pushing away swept directional resolution	0.125
The multi-spectral linear array directional resolution	0.125
		The imaging fabric width	0

Namely

R (t)=0.125R _MTF+ 0.125R _{Panchromatic GSDx}(t)+0.125R _{Panchromatic GSDy}(t)+0.125R _{Multispectral GSDx}(t)+0.125R _{Multispectral GSDy}(t)+0.375R _Snr(t)

Because the task One's name is legion, only take the result of calculation of task 2 as the representative explanation.To be task 2 can pass in the time window image quality scoring with the change curve of observation time to Fig. 7 in fact.

(7) judge time window [t ₁, t ₂] existence

Because the task One's name is legion, only take the computation process of task 2 as the representative explanation.

To task 2, with t ₀=2009-7-2600:00:00 is the reference time, by t ₀=1897 seconds (is t ₀=2009-07-2600:31:37), t _n=2065 seconds (is t _n=2009-7-2600:34:25), the highest moment point t of image quality _m=1959, obtain R (t ₀)=64.34, R (t _m)=90.88, R (t _n)=56.28.

Because R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by the continuous function intermediate value theorem, the t of task 2 ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), need to adopt Secant Method to ask t ₁, t ₂

The result of calculation of other tasks is as follows:

Task 3:

R (t ₀)=56.23, R (t _m)=57.98, R (t _n)=57.98 are because R _Max＜R _p, by the monotonicity of function as can be known, time interval [t ₁, t ₂] do not exist, task 3 is labeled as " not satisfying image quality requires ";

Task 4:

But the communication interval with Beijing Station: R (t ₀)=55.38, R (t _m)=88.20, R (t _n)=55.95 are because R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), need to adopt Secant Method to ask t ₁, t ₂

But the communication interval with Station in Kunming: R (t ₀)=87.93, R (t _m)=87.93, R (t _n)=55.95 are because R _Max＞R _p, R ₀〉=R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁=t ₀, t ₂∈ (t _m, t _n), need to adopt Secant Method to ask t ₂

Task 5:

But the communication interval with Beijing Station: R (t ₀)=56.60, R (t _m)=91.26, R (t _n)=56.78 are because R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), need to adopt Secant Method to ask t ₁, t ₂

But the communication interval with Station in Kunming: R (t ₀)=80.29, R (t _m)=91.26, R (t _n)=56.78 are because R _Max＞R _p, R ₀〉=R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁=t ₀, t ₂∈ (t _m, t _n), need to adopt Secant Method to ask t ₂

Task 6:

But identical with the communication interval of Beijing Station and Station in Kunming: R (t ₀)=56.33, R (t _m)=91.18, R (t _n)=56.82 are because R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), need to adopt Secant Method to ask t ₁, t ₂

(8) adopt Secant Method to reduce time window [t ₁, t ₂]

For passing in fact the interval task of not satisfying the image quality requirement that exists, adopt Secant Method to calculate respectively t ₁, t ₂, result of calculation is as shown in table 6.

What table 6 satisfied image quality can pass the interval in fact

(9) determine the observation duration

Because all tasks are point target in the example, observation duration less than 1 second all can pass time interval in fact less than what satisfy image quality, does not therefore have the task of " do not satisfy and observe the duration ".

(10) pre-service result (as shown in table 7) is exported to the mission planning system, carry out mission planning and scheduling.

The pre-service result of table 7 task

The content that is not described in detail in the instructions of the present invention belongs to those skilled in the art's known technology.

Claims (1)

1. preprocess method to real biography task is characterized in that step is as follows:

(1) according to the camera fabric width mission area band is divided;

(2) determine that according to the maximum angle of pitch of satellite and maximum roll angle and taskbar information satellite is to the visible time interval [t of each band ₀', t _n'], reject the visible time interval of nothing and time interval in the task in shadow zone, ground; Visible time interval [the t of each band ₀', t _n'] by the visible time interval [t of satellite to these four summits of band ₁, t ₂] _k, k=1,2,3,4 seek common ground and reject behind the time interval in shadow zone, ground obtains; Satellite is determined by the maximum angle of pitch and the maximum roll angle of satellite the visible time interval on the single summit of band;

(3) according to ground station location and satellite orbit parameter, but the interval [t of the call duration time of calculating land station and satellite _D0, t _Dn];

(4) according to step (3) but the interval [t of the call duration time that obtains _D0, t _Dn] to visible time interval [t ' ₀, t ' _n] reduce, determine that satellite can carry out the real time interval [t that passes to task ₀, t _n], rejecting does not exist can pass interval task in fact;

(5) with modulation transfer function, the geometric resolution, signal to noise ratio (S/N ratio) and the fabric width that push away the geometric resolution of sweeping direction, linear array direction be as the principal element that affects picture quality, can pass in fact interval [t what step (4) was determined ₀, t _n] the interior function of a single variable R (t) that picture quality is expressed as the time,

R(t)＝η _MTFR _MTF+η _GSDxR _GSDx(t)+η _GSDyR _GSDy(t)+η _snrR _snr(t)+η _breathR _breath(t)，

η in the formula _MTF+ η _GSDx+ η _GSDy+ η _Snr+ η _Breath=1, R _MTF, R _GSDx(t), R _GSDy(t), R _Snr(t), R _Breath(t) be respectively modulation transfer function, the geometric resolution, signal to noise ratio (S/N ratio) and the fabric width that push away the geometric resolution of sweeping direction, linear array direction and the function of a single variable of time relation;

(6) the function of a single variable expression formula that adopts step (5) to obtain calculate respectively in step (4), determine can pass in fact time interval [t ₀, t _n] two end points t ₀And t _nAnd the highest moment point t of interval image quality _mPicture quality R ₀=R (t ₀), R _n=R (t _n), R _Max=R (t _m);

(7) the minimum license image quality of note is R _p, with R _pThe R that obtains with step (6) ₀, R _n, R _MaxCompare, set the tasks satisfy that image quality requires can pass in fact interval [t ₁, t ₂], reject and do not satisfy the task that image quality requires;

(8) adopt Secant Method to calculate the observation duration T of each task band _Last, T _LastFor the summit of observing at first from this band begins to finish duration to the summit of the last observation of this band; Observation duration T when the task band _LastLess than step (7) can pass burst length in fact the time, this task be for executing the task, and all can be executed the task submit to the mission planning system and carry out mission planning and scheduling.

Images