CN102306110B - Task scheduling method with quantity first - Google Patents

Abstract

The invention discloses a task scheduling method with quantity first. The task scheduling method comprises the following steps of: (1) dividing a task region into stripes; (2) calculating a visible time interval of a satellite for each stripe and sequencing according to starting moments of visible time windows so as to acquire a task sequence; (3) calculating an observation lasting time of each task stripe in the task sequence by adopting a secant method; (4) processing tasks in the task sequence in order, judging whether the current task and the last arranged task are conflicted with each other according to an attitude maneuver time of the satellite, if so, not arranging the current task, otherwise, stepping into a step (5); and (5) acquiring a foresight task group of the current task, judging whether the current task and tasks in the foresight task group are conflicted with one another, if not, arranging the current task, otherwise, accepting or rejecting the current task, and if the current task is retained, writing the current task into a satellite motion sequence and taking the current task as a result of the task scheduling.

Description

The method for scheduling task that a kind of quantity is preferential

Technical field

The invention belongs to satellite mission planning and scheduling field, relate to a kind of satellite method for scheduling task.

Background technology

The motor-driven imaging satellite of rapid posture can be realized multiple complicated imaging pattern by the rapid posture maneuverability.Compare with the traditional earth observation satellite that adopts the substar imaging, the rapid posture maneuverability has increased the observation airplane meeting of satellite to target greatly, thereby has stronger observing capacity.Each imaging pattern of the motor-driven imaging satellite of rapid posture all is accompanied by 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 to instruct the reliability of layout and last notes and the real-time problem that instruction is carried out, therefore must set up a cover mission planning and a dispatching system, finish the automated analysis and the processing of observation mission in enormous quantities.

Task scheduling for the ease of the motor-driven imaging satellite of rapid posture, observation mission is carried out pre-service, comprise with task be decomposed into a plurality of can be by the atomic task finished of observation once, promptly be divided into a plurality of single task bands, calculate visible time window, observation duration, the may observe chance etc. of each band.

Method for scheduling task is the core of mission planning and dispatching system, because satellite task scheduling problem is a very complicated combinatorial optimization problem, even it is less to work as the task number, the optimum solution that wants the problem of trying to achieve also is very difficult, the scale of problem makes that usually the complete formula of enumerating method is infeasible, therefore incomplete algorithm (or approximate data) has all been adopted in nearly all existing research, as people such as Bensana in 1996 and the article " Exact and Approximate Methods for the Daily Management of an Earth Observing Satellite " and " Earth Observing Satellite Management " delivered in 1999, study the scheduler routine problem of SPOT-5 satellite, compared complete searching algorithm (depth-first search respectively, dynamic programming, Russian Doll Search) and not exclusively searching algorithm (greedy search, tabu search) calculated performance under the different scales problem-instance.The result shows, when problem scale is little, adopt complete searching algorithm to obtain an optimum solution in the short time, but when problem scale is big, adopt complete searching algorithm just can not reasonably obtain separating of problem in the time, and tabu search can obtain a satisfactory solution of problem in the rational time.In " Towards scheduling over-constrained remote sensing satellites " literary composition that Pemberton delivers in the 2nd international space planning and scheduling meeting in 2000, a kind of method to extensive problem iterative has been proposed, its basic thought is at first according to certain rule all observation requirementses to be sorted, n one group, with all observation requirements groupings, all adopt complete algorithm to try to achieve optimum solution by order of packets to the observation requirements in every group then.In scheduling process, front packet scheduling result will be as the constraint condition of back packet scheduling.

Also have some method for scheduling task in addition at the Application Design of satellite in orbit, in " A Photo Album of Earth:Scheduling LANSDAT 7 Mission Daily A ctivities " literary composition of delivering in calendar year 2001 as William Potter and John Gasch, the derivation algorithm of Landsat 7 satellite resource scheduling problems has been discussed, its main thought is after the demand of considering long-term whole world generaI investigation task and other tasks, and the task of satellite is sub-divided into every day.The scheduler routine problem find the solution proceed step by step: at first calculate all scene informations that satellite can collect in 48 hours, based on the scene selection factor scene is screened then, default priority to scene is adjusted, discharge scheduling scheme by time and priority orders according to depositing capacity admittedly again, when depositing admittedly when using up, do not consider the follow-up work of low priority, just replace low priority task when only occurring the task of high priority with high-priority task.R.Sherwood etc. have delivered " Using ASPEN to automate EO-1activity planning " and " Iterative planning for spacecraft operations using the ASPEN system " respectively at 1998 and 1999, adopt the ASPEN system that mission planning and arrangement are carried out in the daily routines of EO-1 satellite.ASPEN has adopted a kind of local search algorithm based on correction, and its basic thought is at first to generate an initiating task programme, constantly clears up conflict by adjusting variable-value then.

All there is certain limitation in existing dispatching method, can not satisfy practical application request well, mainly shows:

First, the everything of most of method for scheduling task hypothesis satellites is instantaneous finishing, but satellite remote sensor generally all has the side-sway degree of freedom and the pitching degree of freedom of one dimension or two dimension, carrying out when specifying the observation mission of terrain object, can obtain bigger visible time window or better image quality by side-sway or the certain angle of pitching.The motor-driven time that needs consumption can not ignore of satellite side-sway automotive or pitching, and the size of this time span and side-sway or luffing angle and the attitude maneuver ability of satellite are relevant, traditional dispatching method does not consider that satellite carries out the attitude maneuver time between the different observation missions, causes plan and actual disconnection easily;

Second, aspect the conflict judgement and choice of task, existing method based on the expression modeling technique of traditional artificial intelligence scheduling problem, is carried out unified Modeling to satellite fields basically, then problem is converted to single constrained dispatch problem, utilizes the constraint solving technology to find the solution.The deficiency of this method is to cause problem scale bigger owing to the complicacy of constraint, and it is long to find the solution difficulty height, time.For example in the ASPEN system, because the conflict identification and the resolution rule that adopt are cumbersome, it is lower that it finds the solution efficient, and in the application of EO-1, can only dispatch every day to 4 tasks, is difficult to satisfy the requirement of multi-task scheduling;

The 3rd, existing dispatching method is associated with concrete applied satellite mostly, and Model Design is closely related with concrete satellite borne equipment, does not have generality and versatility.

In addition, traditional dispatching method supposes that usually observed object all is a point target, can ignore to the observation duration of task.The motor-driven imaging satellite of rapid posture is by the rapid posture mobility of whole star, can realize the imaging pattern of multiple complexity, as multi-ribbon joining image-forming and continuous strip imaging etc., the observed object that the motor-driven imaging satellite of rapid posture is faced is not only point target, also comprises regional aim, rectangular band target etc., in general, target is big more, and the observation time that needs is just long more, therefore the observation duration of task can not be ignored again, otherwise will cause planning the disconnection fully with actual conditions.Traditional dispatching method is inapplicable for the motor-driven imaging satellite of rapid posture, can't satisfy the demand of the motor-driven imaging satellite task scheduling of rapid posture.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, provide a kind of quantity preferential method for scheduling task, can satisfy the needs of the motor-driven imaging satellite task scheduling of rapid posture.

Technical solution of the present invention is: the satellite method for scheduling task that a kind of quantity is preferential, and step is as follows:

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

(2) calculate the visible time interval [t of satellite according to the maximum angle of pitch of satellite and maximum roll angle and task stripe information to each band ₀, t _n, reject no visible time interval and time interval task in the 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; According to the priority of zero hour of visible time window,, obtain task sequence TaskList then with all task rankings;

(3) the observation duration T of each task band among the employing flat-sawn method calculation task sequence TaskList _Last, T _LastBegin to finish time of being continued to the summit of the last observation of this band for the summit of observing at first from this band;

(4) task among the task sequence TaskList is handled successively, according to the attitude of satellite time kept in reserve between current task and last the arrangement task, judge and whether conflict, if conflict with last task of having arranged, current task can not be arranged, and changes step (7); If do not conflict, enter step (5); The task of described current task for handling;

(5) obtain the prediction task groups Group of current task, judging whether current task and task among the prediction task groups Group exist conflicts, if do not conflict, then current task can be arranged, if there is conflict, then current task is accepted or rejected, and changes step (6); Described prediction task groups Group is all or part of the executing the task after the current task of coming among the task sequence TaskList;

(6) accept or reject current task according to the rule of setting, if keep current task then change step (8), if cast out current task then change step (7);

(7) next task among the Processing tasks sequence TaskList is changeed step (4); If must all tasks are processed among the task sequence TaskList finish, change step (9);

(8) arranged the concluding time t of task with last _EndFor the attitude maneuver zero hour of satellite execution current task, with the visible time window [t of current task ₀, t _n] the t zero hour ₀For observing the zero hour, attitude maneuver action and the observation action of satellite being carried out current task write the satellite action sequence, change step (7);

(9) output satellite action sequence is as the result of task scheduling.

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

(1) the inventive method faces the task One's name is legion at the task scheduling of the motor-driven imaging satellite of rapid posture, the characteristics that problem scale is bigger, adopt the mode of prediction that task is analyzed comparison, whether decision arranges current task, the prediction step-length is set according to actual conditions by the user, and the conflict that has not only solved effectively between the task is judged and choice, and process is simple, computing velocity is fast, can satisfy the constraint of extensive optimization problem for the algorithm time complexity;

(2) the motor-driven imaging satellite of rapid posture possesses multiple complicated imaging pattern, and attitude maneuver is frequent between the task, and consumed time has nothing in common with each other, and observed object is not of uniform size, and the observation duration also has than big difference.The inventive method is according to the specifying information of satellite and task, calculate the attitude maneuver time between accurate task, according to the accurate task observation duration, judge whether task exists conflict again, improve the precision of scheduling, satisfied the needs of the motor-driven imaging satellite task scheduling of rapid posture;

(3) the inventive method is applicable to the scheduling that wall scroll band task and multi-ribbon task are mixed, and has stronger versatility;

(4) the inventive method is arranged in the most approaching previous moment point of having arranged task in the visible time window with task, farthest avoid waste of time, strive for carrying out the observation mission of greater number, to improve the service efficiency of the motor-driven imaging satellite of rapid posture, bring into play its dynamical advantage, and all Model Design do not rely on concrete satellite, have stronger versatility.

Description of drawings

Fig. 1 is the process flow diagram of the inventive method;

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

Fig. 3 judges the process flow diagram whether prediction task groups and current task conflict for the present invention;

Fig. 4 accepts or rejects the process flow diagram of current task according to rule for the present invention.

Embodiment

As shown in Figure 1, the flow process of the inventive method comprises: 1. the mission area band is divided; 2. calculate the position and the speed of satellite; 3. calculate the visible time interval of satellite to each task band; 4. calculate the observation duration to mission area; 5. judge whether current task (handling of task) is looked forward to the prospect; 6. judge whether the prediction task groups exists with current task and conflict; 7. accept or reject current task according to rule; 8. judge whether to arrange current task; 9. arrangement current task; 10. export the task scheduling result.Detailed step is as follows:

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 promptly obtain mission area.Among the present invention, adopt following method that mission area is divided into the band that is parallel to satellite orbit, be convenient to satellite and implement observation:

1. rolling off the production line from the satellite star, is width with substar camera fabric width (the satellite side-sway angle is 0 o'clock a camera fabric width), does the parallel lines that star rolls off the production line, until covering mission area; It is the set of substar (the vertical projection point that satellite position point is gone up at the earth's surface) that star rolls off the production line;

2. do the vertical line that the satellite star 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 L1 and D1 respectively, L2 and D2 obtain and the roll off the production line intersection point of parallel lines of step 1 culminant star, constitute tetragonal 4 intersection points and promptly 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, calculate the position and the speed of satellite

The method that employing is found the solution dynamics of orbits equation numerical integration is forecast orbital position and the speed of satellite under the J2000 inertial coordinates system in the limiting time section.

According to the orbital tracking of satellite, can extrapolate the orbital position R under the task scheduling initial time J2000 inertial coordinates system _AstWith speed V _Sat, adopt the Cowell method to find the solution dynamics of orbits equation (selecting Gauss perturbed motion equation for use) again, 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 theory " (Liu Linzhu, 2000) book that National Defense Industry Press publishes.The J2000 inertial coordinates system defines the document that sees reference " coordinate system additional perturbation and reference frame are selected problem in the earth satellite motion " (" space science journal " 2008 the 28th the 2nd phases of volume, author Liu Lin, Tang Jingshi).

Three, calculate the visible time interval of satellite to each task band

To each band, the orbital position R that obtains according to 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 observation window at last in the shadow zone, ground.The example that is calculated as with a band describes below.

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.Only describe below 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, calculate the t position vector R of impact point under the J2000 inertial coordinates system constantly according to the earth longitude and latitude of impact point _{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, calculate impact point the earth's core distance then:

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 theory " (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 primitive transformation matrix respectively around the rotation of x, y, z axle:

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

Calculate the vector of satellite directed towards ground impact point under the J2000 inertial coordinates system then:

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, the definition of satellite orbit coordinate system 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 the observation attitude angle of satellite to target

(changeing preface 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 the corresponding relation of time t and crab angle, roll angle and the angle of pitch in the attitude angle of satellite definite object point respectively.

2. each the moment point satellite that obtains according to attitude of satellite maneuvering range and step 1 points to the attitude angle on each summit of band, calculates the visible time interval [t of satellite to 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, so has only 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] _kSet for the t that satisfies above-mentioned condition.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, calculate the visible time interval [t of satellite to band 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, and promptly obtain the visible time interval [t of satellite to band ₀, t _n].

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

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

[t between the visible range that step 3 is obtained 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.

Sun altitude is relevant with the time, and computation process is seen " spacecraft flight principle of dynamics " (Xiao Yelun writes, nineteen ninety-five) that the Yuhang Publishing House publishes.

5. obtain the visible time window [t of all mission areas ₀, t _n] after, according to the t zero hour of this window ₀Priority, with all task rankings, the task sequence TaskList that is arranged in chronological order.

Four, calculate the observation duration of each task band

The observation duration of band, promptly, depend on the length of band from beginning to observe the duration of end observation.To a multi-ribbon task,, can obtain the observation duration of all bands because therefore the equal in length of all bands only needs an optional band to calculate.To each band, at first the satellite that obtains according to the step 1 of third part points to the attitude angle on each summit, adopt the flat-sawn method to calculate the beginning observation time and the end observation time of band again, 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.Be that example describes with a band below:

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 the flat-sawn method to calculate the angle of pitch is 0 o'clock, satellite points to the time on each summit of band.

Satellite is to the attitude maneuver ability decision by satellite of visible time of target, 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 promptly 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, promptly as Pitch (t ₁) Pitch (t ₂)＜0 o'clock,

And satisfy Pitch (t _p)=0 adopts the flat-sawn method can obtain t _p

Flat-sawn 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.The flat-sawn method has detailed explanation in " numerical analysis " (Yan Qingjin writes, 2000) book that publishing house of BJ University of Aeronautics ﹠ Astronautics publishes.

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

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

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

T _last＝T _end-T _start

Five, judge whether current task is looked forward to the prospect

Task among the task sequence TaskList is handled successively.If current task Task (i) is first task among the task sequence TaskList, make t _End=0, attitude

Equal the initial attitude of satellite

(input value); If current task Task (i) is not first task among the task sequence TaskList, can from previous task handling result, obtain the concluding time t that last has arranged task _End, and execute the attitude of satellite after the task

According to the attitude maneuver time between current task and last the arrangement task, judge whether conflict with last task of having arranged, if conflict, current task need not be looked forward to the prospect and can not be arranged, current task is labeled as " with arranging task conflict ", changes the 8th part; If do not conflict, change the 6th part.

The purpose of prediction is for when considering current task, considers its influence and contingent conflict to follow-up observation mission in advance, to raise the efficiency.

Concrete steps are as follows:

1. the attitude maneuver time t between calculation task _m

To finish the attitude that last has arranged task

As the attitude maneuver reference attitude of carrying out current task, the attitude maneuver time t between calculation task _m

(1) is t _mAn empirical value is set;

(2) note t=t _End+ t _m, t _EndFor last has arranged the deadline of task, obtain the orbital position R of t moment satellite according to the result of second portion _SatWith speed V _Sat

Be engraved in the orbital position under the J2000 coordinate system, the attitude angle of speed calculation t satellite sensing constantly current task during (3) according to satellite t

Computing method are with third part step 1;

(4) calculate t _mThe motor-driven Euler's angle of rotation Δ Ω of the attitude of satellite in time.Known satellite has been observed the attitude angle of previous task

Begin to observe the attitude angle of current task with satellite

Can obtain the Eulerian angle between these two vectors, promptly satellite is at t _mEuler's angle of rotation Δ Ω in time, method is as follows:

Calculate Δ Ω according to following formula:

$\mathrm{\Δ\Ω}=\arccos \left(V_1^T{V}_2\right);$

(5) based on satellite appearance control ability (Time _i, A _i), i=1,2,3 ..., adopt linear interpolation method to calculate the motor-driven t of the attitude of satellite _mThe changing value Δ Ω of the Euler's angle of rotation after the time ^*

(6) allowable error of note ε for setting makes f (t _m)=| Δ Ω ^*-Δ Ω |, if f (t _m)＞ε changes (7); If f (t _m)≤ε, t _mBe the attitude maneuver time of being asked, iteration finishes;

(7) adopt Newton method solving equation f (t _mStep (2) is changeed in)=0.Newton method has detailed explanation in " numerical analysis " (Yan Qingjin writes, 2000) book that publishing house of BJ University of Aeronautics ﹠ Astronautics publishes.

2. judge current task whether with arrange task conflict

Note t=t _End+ t _m, according to t and best observation moment t _BestRelation, judge whether current task and last task of having arranged conflicts.

(1) if t≤t _Best, current task is not conflicted with arranging task, changes the 6th part;

(2) if t＞t _Best, current task with arrange task conflict, current task is labeled as " time conflict can't be finished ", change the 8th part.

Six, judging whether the prediction task groups exists with current task conflicts

The prediction task groups is that the dense degree, algorithm efficiency etc. according to task are taken all factors into consideration, from task sequence TaskList, choose the current task task groups of the task composition of some (being called prediction step-length M) afterwards, be used for comparing, reduce possible conflict with current task.

Flow process as shown in Figure 3, concrete steps are as follows:

1. prediction step-length M is set, from task sequence TaskList, obtains M task behind the current task Task (i), put into the formation Group that looks forward to the prospect;

2. to the task Group (k) of prediction in the formation, k=1 ..., M, carry out:

(1) judge whether Group (k) conflicts with Task (i), concrete grammar is judged current task consistent with last method of having arranged task whether to conflict (look Task (i) and arranged task for last) with the 5th part.If (2) are changeed in conflict; If do not conflict and k ≠ M, make k=k+1 change 2, k=M changes the 8th part;

(2) judge whether Group (k) conflicts with last task of having arranged, concrete grammar judges that with the 5th part current task is consistent with last method of having arranged task whether to conflict.If do not conflict, change the 7th part, if conflict then Group (k) can not arrange, make k=k 10, change 2.

Seven, accept or reject current task according to rule

Choice rule during according to task conflict compares Task (i) and Group (k), determines whether to arrange current task, concrete rule is formulated as required, for example, arranges the high task of priority earlier, arrange short task of observation duration then, or the like.Be example with above-mentioned rule below, the task of how accepting or rejecting is described, as shown in Figure 4:

1. the priority P RI (Group (k)) and the PRI (Task (i)) that compare Group (k) and Task (i):

(1) if PRI (Group (k))＞PRI (Task (i)), then Task (i) can not arrange, and is marked as " time conflict can't be finished ", changes the 8th part;

(2) if PRI (Group (k))＜PRI (Task (i)) needs the relatively size of k and M, if k＜M makes k=k+1, change 2 of the 6th part, if k=M changes the 8th part;

(3) if PRI (Group (k))=PRI (Task (i)), 2 below changeing;

2. the observation duration of comparing Group (k) and Task (i):

(1) if T _Last(Group (k))＜T _Last(Task (i)), Task (i) can not arrange, and is marked as " time conflict can't be finished ", changes the 8th part;

(2) if T _Last(Group (k))＞T _Last(Task (i)), needs compare the size of k and M, if k＜M makes k=k+1, if k=M changes the 8th part;

(3) if T _Last(Group (k))=T _Last(Task (i)), optional conduct person of being rejected if Task (i) is selected, then is labeled as it " time conflict can't be finished " in two tasks, changes the 8th part; If Group (k) is selected, if k＜M makes k=k+1, change 2 of the 6th part, if k=M changes the 8th part.

Eight, judge whether to arrange current task

If current task is retained, then change Session 9, if cast out current task then change next task among the Processing tasks sequence TaskList, change the 5th part; If must all tasks are processed among the task sequence TaskList finish, then change the tenth part.

Nine, arrange current task

If t _End+ t _m〉=t ₀, make t _s=t _End+ t _mIf t _End+ t _m＜t ₀, then make t _s=t ₀

For wall scroll band task, the observation t finish time _e=t _s+ T _Last, for the multi-ribbon task, the observation t finish time _e=t _s+ t _m'+T _Last, t _m' be the attitude maneuver time sum of the bar interband of current task, concrete computing method are with the 5th part steps 1.

Arranged the concluding time t of task with last _EndBe the attitude maneuver zero hour that satellite is carried out current task, t _sBe the observation zero hour of current task, attitude maneuver action and the observation action of satellite being carried out current task write satellite action sequence: t _EndTo t _End+ t _mBetween satellite carry out attitude maneuver, reach targeted attitude Then at t _sConstantly begin observation, at t _eFinish observation constantly.

Ten, output task scheduling result

After handling all tasks among the task sequence TaskList, the reason that output satellite action sequence and being labeled of task can not be finished is as the result of task scheduling.Attitude maneuver is to finishing the attitude that next task should have immediately after finishing an observation mission for satellite, and wait observation begins observation constantly temporarily then, carries out attitude maneuver again after finishing to observe.

Embodiment

Consider a motor-driven imaging satellite of rapid posture that runs on the sun synchronization circular orbit, epoch, July in 2009,00:00:00.000UTC on the 26th wink radical was semi-major axis 7051.2km constantly, 97.3087 ° of orbit inclinations, 249.758 ° of right ascension of ascending node, 0 ° of latitude argument.Attitude of satellite maneuvering range is pitch orientation and rotating direction ± 45 °, and appearance control ability is 0 °/15s, 15 °/25s, and 30 °/35s, 45 °/45s.

The geographical latitude and longitude information of target is as shown in table 1, and the longitude on four summits of each target and latitude are corresponding one by one in order.

The geographical longitude and latitude of table 1 target

The preferential method for scheduling task step of quantity is as follows:

(1) the mission area band is divided

According to the longitude and latitude and the sub-satellite point of camera fabric width, mission area, mission area is carried out band divide, it is as shown in table 2 to divide the result.

Table 2 mission area band is divided the result

(2) calculate visible time window

According to orbit elements of satellite, calculate 00:00:00.000UTC on July 27,00:00:00.000UTC to 2009 year on the 26th July in 2009 satellite orbital position, speed under the J2000 coordinate system in the time period, calculate then each whole second constantly satellite to the observation angle of each task.According to attitude of satellite maneuvering range, obtain its visibility window of satellite and task, result of calculation 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
			1	03:51:26.397	03:54:51.815
2	03:55:14.229	03:58:37.684

3	03:56:09.833	03:59:35.814
			4	03:56:18.049	03:59:43.984
5	03:56:28.176	03:59:51.465
			6	03:56:57.775	04:00:22.775
7	03:51:41.532	03:55:08.828
			8	03:52:11.926	03:55:36.956
9	03:54:10.381	03:57:36.511
			10	03:57:16.509	04:00:39.41

The task sequence TaskList that arranges according to the zero hour of visible time window is: 1,7,8,9,2,3,4,5,6,10.

(3) the observation duration of calculation task

According to the attitude angle of satellite sensing task, adopt the flat-sawn method to obtain the observation duration of task, the result is as shown in table 4.

The table 4 observation duration

Task number	Observation duration t last(s)
		1	1.944
2	(29.807 4 band)
		3	(28.194 4 band)
4	(32.359 4 band)
		5	(6.825 2 band)
6	1.775
		7	0.848
8	(9.875 2 band)
		9	(4.734 2 band)
10	(14.338 3 band)

(4) successively the task among the task sequence TaskList is handled

Below with No. 3 tasks as current task, the idiographic flow of this method is described.

(5) judge whether current task is looked forward to the prospect

According to the order of TaskList sequence, No. 1, No. 7, No. 8, No. 9 and No. 2 tasks are handled, obtaining last arrangement task from the result of front is No. 2 tasks, it observes concluding time t _End=03:56:58.646, attitude of satellite when observation finishes

According to the observation concluding time and the attitude of No. 2 tasks, calculate satellite from

Attitude maneuver is to the attitude maneuver time t of No. 3 tasks of observation _m=29.677s.

Because t=t _End+ t _m=03:57:28.323, t ₀≤ t≤t+t _Last≤ t _n, therefore No. 3 tasks are not conflicted with No. 2 tasks, change step (6).

(6) judge whether the prediction task groups exists with current task and conflict, and according to rule choice current task

Prediction step-length M=3 is set, and the prediction task groups is made up of No. 4, No. 5 and No. 6 tasks.

The first step compares No. 4 tasks and No. 3 tasks.The observation concluding time t of No. 3 tasks _End=03:59:15.908, observation finishes attitude

Attitude maneuver time t between No. 3 tasks and No. 4 tasks _m=15.61s is for No. 4 tasks, t=t _End+ t _m=03:59:31.518, t ₀≤ t≤t _n＜t+t _Last, so No. 3 tasks and No. 4 task conflict.Judge that according to identical method No. 4 task is not conflicted with No. 2 tasks, therefore must between No. 3 tasks and No. 4 tasks, accept or reject according to rule.According to the order of rule, No. 3 task is identical with the priority of No. 4 tasks, and the may observe chance is also identical, and therefore the observation duration of No. 3 tasks gives up No. 4 task less than No. 4 tasks.

In second step, No. 5 tasks and No. 3 tasks are compared.The observation concluding time t of No. 3 tasks _End=03:59:15.908, observation finishes attitude

Attitude maneuver time t between No. 3 tasks and No. 5 tasks _m=15.63s is for No. 5 tasks, t=t _End+ t _m=03:59:31.538, t ₀≤ t≤t＜t _Last, so No. 3 tasks and No. 5 task conflict.Judge that according to identical method No. 5 task is not conflicted with No. 2 tasks, therefore must between No. 3 tasks and No. 5 tasks, accept or reject according to rule.According to priority, the priority of No. 3 tasks is that the priority of 8, No. 5 tasks is 6, gives up task No. 5.

In the 3rd step, No. 6 tasks and No. 3 tasks are compared.The observation concluding time t of No. 3 tasks _End=03:59:15.908, observation finishes attitude

Attitude maneuver time t between No. 3 tasks and No. 6 tasks _m=20.852s, t=03:59:36.76, t _n≤ t≤t+t _Last≤ t _n, No. 3 task is not conflicted with No. 6 tasks.

(7) judge whether to arrange current task.No. 3 task is retained, and can arrange, and changes next step.

(8) arrange current task

Because t _End+ t _m〉=t ₀, so t _s=t _End+ t _m=03:57:28.323.

No. 3 task is one 4 band task, and the attitude maneuver time that calculates the bar interband is respectively: 28.56s, 27.249s and 23.582s, so t _m'=79.391s, the observation t finish time _e=t _s+ t _m'+t _Last=03:59:15.908.

With t _End=03:56:58.646 is the attitude maneuver zero hour that satellite is carried out No. 3 tasks, t _s=03:57:28.323 is for observing the zero hour, and attitude maneuver action and the observation action of satellite being carried out current task write the satellite action sequence: satellite carries out attitude maneuver between the 03:56:58.646 to 03:57:28.323, reaches targeted attitude

Begin observation constantly at 03:57:28.323 then, finish observation constantly at 03:59:15.908.

(9) output task scheduling result

After handling all tasks among the task sequence TaskList, output satellite action sequence (as shown in table 5), and the reason that can not finish of being labeled of task are as the result of task scheduling.

Table 5 satellite action sequence

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. method for scheduling task that quantity is preferential is characterized in that step is as follows:

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

(2) calculate the visible time interval [t of satellite according to the maximum angle of pitch of satellite and maximum roll angle and task stripe information to each band ₀, t _n], the visible time interval in shadow zone, rejecting 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; According to the priority of zero hour of visible time window,, obtain task sequence TaskList then with all task rankings;

(3) the observation duration T of each task band among the employing flat-sawn method calculation task sequence TaskList _Last, T _LastBegin to finish time of being continued to the summit of the last observation of this band for the summit of observing at first from this band;

(4) task among the task sequence TaskList is handled successively, carry out the required time of attitude maneuver according to satellite between current task and last the arrangement task, judge and whether conflict, if conflict with last task of having arranged, current task can not be arranged, and changes step (7); If do not conflict, enter step (5); The task of described current task for handling;

(5) obtain the prediction task groups Group of current task, judging whether current task and task among the prediction task groups Group exist conflicts, if do not conflict, then current task can be arranged, and changes step (8); If there is conflict, then current task is accepted or rejected, change step (6); Described prediction task groups Group is all or part of the executing the task after the current task of coming among the task sequence TaskList;

(6) accept or reject current task according to the rule of setting, if keep current task then change step (8), if cast out current task then change step (7);

(7) next task among the Processing tasks sequence TaskList is changeed step (4); If must all tasks are processed among the task sequence TaskList finish, change step (9);

(8) if t _End+ t _m〉=t ₀, make t _s=t _End+ t _mIf t _End+ t _m＜t ₀, then make t _s=t ₀, arranged the concluding time t of task with last _EndBe the attitude maneuver zero hour that satellite is carried out current task, t _sBe the observation zero hour of current task, attitude maneuver action and the observation action of satellite being carried out current task write the satellite action sequence, change step (7); T wherein _mFor satellite has arranged attitude after the task termination to adjust to the time kept in reserve of the required targeted attitude of current task, t from last ₀Visible time window [t for current task ₀, t _n] the zero hour;

(9) output satellite action sequence is as the result of task scheduling.

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