A dynamic scheduling method for ground station resources for satellite emergency missions

Abstract

The invention discloses a ground station resource dynamic scheduling method for satellite emergency tasks, which relates to the field of station network resource scheduling in aerospace measurement and control, and comprises: step S1: receiving an emergency task; step S2: scheduling the emergency task by adopting a direct insertion method; step S3: rescheduling conventional tasks by adopting an indirect insertion method and a rescheduling method; step S4: adopting a multi-group solution selection method, generating multiple groups of solutions by using a thread pool, and then selecting a scheduling scheme; the invention can obtain scheduling schemes for emergency tasks and conventional tasks, and obtain a higher task satisfaction rate.

Description

Technical Field

[0001] The present invention relates to the field of station network resource scheduling in aerospace measurement and control, and in particular to a ground station resource dynamic scheduling method for satellite emergency tasks. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Dynamic scheduling of satellite-to-ground station resources refers to the process of adjusting the allocation of ground station resources in real time according to satellite mission requirements and operating status. In order to maximize the use of ground station resources and achieve efficient completion of tasks, it is necessary to dynamically schedule and manage ground station resources. The problem of dynamic scheduling of satellite-to-ground station resources is essential for the application of operations research, and this problem has been recognized as an NP-hard problem.

[0004] Existing technologies use integer programming models, develop satellite overpass construction graph models, establish acyclic directed graph models, etc. to solve satellite scheduling problems. Some scholars also use hybrid ant colony optimization algorithms, quantum discrete particle swarm optimization algorithms, improved particle swarm algorithms, hybrid genetic particle swarm optimization algorithms, etc. to solve such problems. Existing technologies may have problems such as mission satisfaction rate and response real-time performance not meeting standards, mainly because the number of satellite missions is large, the constraints are complex and the degree of coupling is high, and resources are limited. When solving these problems, it is necessary to overcome the difficulty of limited resources, meet the complex constraints of the tasks, and make the objective function achieve the optimal value as much as possible. Summary of the invention

[0005] The purpose of the present invention is to provide a ground station resource dynamic scheduling method for satellite emergency tasks in view of the problems existing in the prior art, thereby solving the above problems.

[0006] The technical solution of the present invention is as follows:

[0007] A method for dynamic scheduling of ground station resources for satellite emergency missions includes:

[0008] Step S1: receiving an urgent task;

[0009] Step S2: Use direct insertion method to schedule urgent tasks;

[0010] Step S3: rescheduling the regular tasks by using the indirect insertion method and the rescheduling method;

[0011] Step S4: adopt a multi-solution selection method, use the thread pool to generate multiple solutions and then select a scheduling plan.

[0012] Furthermore, the step S1 comprises:

[0013] Based on constraints, resources and regular scheduling results, urgent tasks are received.

[0014] Furthermore, the step S2 comprises:

[0015] Step S21: Prioritize the urgent tasks according to their urgency;

[0016] Step S22: Bind the emergency task to the designated satellite and filter out all arcs corresponding to the satellite;

[0017] Step S23: Arrange arc segments for emergency tasks using the direct insertion method.

[0018] Furthermore, the step S23 includes:

[0019] According to the priority of the emergency task, arc segments are allocated to each emergency task in turn. Among all available arc segments, the arc segment with the smallest duration difference with the emergency task and not occupied by regular tasks is given priority.

[0020] Further, step S3 includes:

[0021] Step S31: Counting the occupancy of conventional task arcs;

[0022] Step S32: For conventional tasks whose arc segments are not occupied by urgent tasks, the original arc segments are maintained; for conventional tasks whose arc segments are occupied by urgent tasks, the indirect insertion method and the rescheduling method are used to reschedule.

[0023] Furthermore, the step S32 includes:

[0024] First, consider whether the arc segment can be shared with the emergency task; if so, keep the original arc segment unchanged; if not, search the entire arc segment and reallocate a suitable arc segment for it.

[0025] Furthermore, the step S4 comprises:

[0026] Determine whether all urgent tasks meet hard constraints;

[0027] Determine whether there is no time overlap between tasks on all antennas;

[0028] Determine whether there is no time overlap among the tasks on all satellites.

[0029] Furthermore, when all emergency tasks meet the hard constraints, there is no time intersection between tasks on all antennas, and there is no time intersection between tasks on all satellites, the scheduling is determined to be successful and a scheduling plan is output; otherwise, the scheduling fails.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The method for dynamic scheduling of ground station resources for satellite emergency tasks comprises: step S1: receiving an emergency task; step S2: scheduling the emergency task by adopting a direct insertion method; step S3: rescheduling a conventional task by adopting an indirect insertion method and a rescheduling method; step S4: adopting a multi-group solution selection method, using a thread pool to generate multiple groups of solutions and then selecting a scheduling scheme; the present invention can obtain scheduling schemes for emergency tasks and conventional tasks, and obtain a higher task satisfaction rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart of a method for dynamic scheduling of ground station resources for satellite emergency missions;

[0033] Figure 2 Direct insertion method schematic for emergency tasks;

[0034] Figure 3 Scheduling principle diagram of indirect insertion method for regular tasks;

[0035] Figure 4 Schematic diagram for checking the correctness of scheduling results. DETAILED DESCRIPTION

[0036] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0037] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0038] Embodiment 1

[0039] See also Figure 1 , a ground station resource dynamic scheduling method for satellite emergency tasks specifically includes the following steps:

[0040] Step S1: receiving an urgent task;

[0041] Step S2: Use direct insertion method to schedule urgent tasks;

[0042] Step S3: rescheduling the regular tasks by using the indirect insertion method and the rescheduling method;

[0043] Step S4: adopt a multi-solution selection method, use the thread pool to generate multiple solutions and then select a scheduling plan.

[0044] In this embodiment, specifically, step S1 includes:

[0045] Based on constraints, resource status and regular task allocation, a batch of urgent tasks are received, and the urgent tasks will be planned based on constraints, resource status and regular task allocation.

[0046] It should be noted that the constraints considered in this embodiment include: duration constraints, ascending and descending orbit constraints and satellite constraints; in the early stage of the execution of this method, it is necessary to read the database, which includes: satellites, ground stations, constraints and available arcs and other information for subsequent use.

[0047] In this embodiment, specifically, step S2 includes:

[0048] Step S21: Prioritize the urgent tasks according to their urgency; that is, for the numerous urgent tasks that arrive, they need to be prioritized according to their urgency, and the more urgent the task, the higher the priority; and the urgent tasks with high priority have the right to be scheduled first;

[0049] Step S22: Bind the emergency task to the designated satellite and filter out all arcs corresponding to the satellite; that is, determine the start time and end time of the emergency task, thereby knowing its duration and judging whether the arc can be used to schedule the emergency task;

[0050] Step S23: Arranging arc segments for emergency tasks by using direct insertion method;

[0051] In this embodiment, if Figure 2 As shown, the step S23 includes:

[0052] According to the priority of the emergency task, arc segments are allocated to each emergency task in turn. Among all available arc segments, the arc segment with the smallest duration difference with the emergency task and not occupied by regular tasks is given priority.

[0053] The so-called direct insertion means that the emergency task is directly arranged in the arc segment regardless of whether the arc segment is occupied by a regular task. In the scheduling process, the priority of all emergency tasks is higher than that of regular tasks. Similarly, there are different priorities within the emergency tasks. Emergency tasks with higher priorities can be scheduled before emergency tasks with lower priorities. According to the priority of the emergency task, each emergency task is assigned an arc segment in turn. Among all available arc segments, the arc segments that are not occupied by regular tasks are given priority. Among the many arc segments that do not contain regular tasks and meet the constraints of the emergency tasks, the arc segment with the smallest difference between the arc segment duration and the duration of the emergency task is given priority. If the arc segment will conflict with other emergency tasks, an arc segment with a larger duration difference can be selected in the arc segment that does not contain regular tasks, that is, the requirement for a small duration difference can be relaxed, but the principle of not occupying the arc segment of regular tasks is still adhered to. In the above case, the requirements cannot be met, and the arc segment that meets the requirements can only be found in the arc segment that contains regular tasks. Therefore, it can be seen that when scheduling the emergency task by direct insertion method, try to avoid occupying the arc segment of regular tasks. Only when the arc segment that does not occupy the regular task arc segment cannot find an arc segment that meets the requirements, the regular task arc segment will be occupied. It can be seen from the above direct insertion scheduling process that when allocating arc segments for emergency tasks, it is ensured that the arc segment arrangement of the emergency task will not conflict with other emergency tasks on the antenna.

[0054] It should be noted that in the direct insertion method of emergency tasks, all emergency tasks have higher priority than regular tasks. When scheduling emergency tasks, although regular task arcs can be directly preempted, this situation should be avoided as much as possible, and regular task arcs can be preempted when necessary.

[0055] Furthermore, the direct insertion method is expressed by the following formula:

[0056] st.TotalID(n) ≤ st.Xk

[0057] et.TotalID(n) ≥ et.Xk

[0058] The above Xk represents the kth emergency task, and the emergency task is expressed as X={X1, X2, X3........}. st represents the start time, and et represents the end time. The above two formulas express that if an arc segment occupied by the satellite n corresponding to the emergency task satisfies the start time earlier than the start time of the emergency task k, and the arc segment end time is later than the end time of the emergency task k, and the arc segment contains the time period required to be occupied by the emergency task k, then the arc segment can be added to the available arc segment list AlternativeID(n) of the emergency task k, and then the arc segment occupied by the regular task is removed from AlternativeID(n), and the final result is saved in Temporary(k). This is done to avoid conflicts with the arc segments occupied by regular tasks as much as possible, and to reduce the workload in the subsequent rescheduling of regular tasks. It is stipulated that the final emergency task arc segment allocation result is stored in the list FinalID, and the stored elements are the corresponding arc segment ID numbers.

[0059] Duration.Xk = et.Xk - st.Xk

[0060] Duration.Temporary(k) = et.Temporary(k) - st.Temporary(k)

[0061] TimeDifference = Duration.Temporary(k) - Duration.Xk

[0062] In the above formula, the duration is the end time minus the start time, and the time difference is the duration of the available arc segment corresponding to the emergency task k, Duration.Temporary(k), minus the duration Duration.Xk required by the emergency task k itself. Select the minimum value Minimum from the obtained time difference to determine whether the arc segment corresponding to the minimum value does not conflict with the execution process of the previous k-1 emergency tasks. The non-conflict here refers to whether all the scheduled emergency tasks on the antenna corresponding to the arc segment do not conflict in time. This is done to make the feasibility of the scheduling plan more likely when checking after all emergency tasks and regular tasks are scheduled. The judgment of conflict or not is determined by the function OverLapped, which is for all emergency tasks on a specific antenna, and its input form is:

[0063] [[st1,et1],[st2,et2],[st3,et3]......]

[0064] The pseudo code for the direct insertion method is as follows:

[0065]

[0066] In this embodiment, specifically, Figure 3 As shown, the step S3 includes:

[0067] Step S31: Count the occupancy of arc segments of routine tasks; it should be noted that, as can be seen from step S2, some original arc segments of routine tasks may be occupied by emergency tasks, so it is necessary to count and record the routine tasks of the arc segments occupied by emergency tasks;

[0068] Step S32: For regular tasks whose arc segments are not occupied by urgent tasks, the original arc segments are maintained (the condition is that there is still enough time to complete regular tasks after the urgent tasks are completed in the arc segment. In this case, regular tasks can be arranged after the urgent tasks, and there is no need to arrange new arc segments for regular tasks); for regular tasks whose arc segments are occupied by urgent tasks, indirect insertion method and rescheduling method are used for rescheduling.

[0069] In this embodiment, specifically, step S32 includes:

[0070] First, consider whether the arc segment can be shared with the emergency task; if so, keep the original arc segment unchanged; if not, search the entire arc segment and reallocate a suitable arc segment for it.

[0071] That is, any task is constrained by satellites, because both emergency and regular tasks are assigned to specific satellites, and tasks that do not belong to the satellite cannot be completed across satellites. When rescheduling regular tasks, the rule is: according to the satellite corresponding to the regular task, traverse all available arcs of the satellite to find an arc that meets the constraints of the regular task and does not conflict with other regular tasks and emergency tasks; after the above two operations, all regular tasks will be scheduled and completed.

[0072] Furthermore, the pseudo code of the indirect insertion algorithm is as follows:

[0073]

[0074]

[0075] In this embodiment, specifically, Figure 4 As shown, the step S4 includes:

[0076] Determine whether all urgent tasks meet hard constraints;

[0077] Determine whether there is no time overlap between tasks on all antennas;

[0078] Determine whether there is no time overlap among the tasks on all satellites.

[0079] In this embodiment, specifically, when all emergency tasks meet hard constraints, there is no time intersection between tasks on all antennas, and there is no time intersection between tasks on all satellites, it is determined that the scheduling is successful and a scheduling plan is output; otherwise, the scheduling fails.

[0080] That is, the thread pool can be used to generate multiple scheduling plans for the same group of emergency tasks; the advantages and disadvantages of different scheduling plans are judged based on the correctness of the scheduling and the completion of the emergency task scheduling. The judgment of whether the emergency task scheduling is correct is carried out from three aspects. The first aspect is to check whether all emergency tasks and their assigned arc segments correspond to the satellites and start and end times. The second aspect is to check whether there is a time conflict problem in the use of arc segments on the three hundred antennas. The third aspect is to check whether there is no time conflict for the emergency tasks that all satellites need to complete.

[0081] The direct insertion method for urgent tasks and the indirect insertion method and rescheduling method for routine tasks have ensured the above three aspects, that is, the scheduling scheme must be feasible. Among these groups of scheduling schemes, the one with correct scheduling and the highest scheduling rate is the final result.

[0082] Embodiment 2

[0083] This embodiment designs the following four experimental scenarios:

[0084] Experimental scenario 1: The total number of satellites is 500, the total number of conventional tasks is 2315, and the number of emergency tasks that a single satellite needs to complete is 1, that is, when the total number of emergency tasks is 500, the average scheduling success rate of emergency tasks is 99.6%.

[0085] Experimental scenario 2: The total number of satellites is 500, the total number of conventional tasks is 2315, and the number of emergency tasks that a single satellite needs to complete is 2, that is, when the total number of emergency tasks is 1000, the average scheduling success rate of emergency tasks is 88.4%.

[0086] Experimental scenario 3: When the total number of satellites is 500 and the total number of conventional tasks is 2315, and the number of emergency tasks that a single satellite needs to complete is 3, that is, when the total number of emergency tasks is 1500, the average scheduling success rate of emergency tasks is 75.0%.

[0087] Experimental scenario 4: The total number of satellites is 500, the total number of conventional tasks is 2315, and the number of emergency tasks that a single satellite needs to complete is 4, that is, when the total number of emergency tasks is 2000, the average scheduling success rate of emergency tasks is 65.7%.

[0088] From the above four situations, it can be seen that the algorithm can achieve a higher success rate of emergency task scheduling.

[0089] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

[0090] This background section is provided to generally present the context of the invention, and the work of the presently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither explicitly nor implicitly admitted to be prior art to the present invention.

Claims

1. A method for dynamic scheduling of ground station resources for satellite emergency missions, characterized in that: include: Step S1: receiving an urgent task; Step S2: Use direct insertion method to schedule urgent tasks; Step S3: rescheduling the regular tasks by using the indirect insertion method and the rescheduling method; Step S4: adopting a multi-solution selection method, using a thread pool to generate multiple solutions and then selecting a scheduling solution; The step S1 comprises: Based on constraints, resources and regular scheduling results, an urgent task is received; the constraints include: duration constraints, orbit ascending and descending constraints and satellite constraints; The step S2 comprises: Step S21: Prioritize the urgent tasks according to their urgency; Step S22: Bind the emergency task to the designated satellite and filter out all arcs corresponding to the satellite; Step S23: using the direct insertion method to arrange arc segments for the emergency tasks; The step S23 comprises: According to the priority of the emergency task, arc segments are allocated to each emergency task in turn. Among all available arc segments, the arc segment with the smallest duration difference with the emergency task and not occupied by regular tasks is given priority. Step S3 includes: Step S31: Counting the occupancy of conventional task arcs; Step S32: For conventional tasks whose arc segments are not occupied by emergency tasks, the original arc segments are maintained; for conventional tasks whose arc segments are occupied by emergency tasks, the indirect insertion method and the rescheduling method are used to reschedule; The step S32 comprises: First, consider whether the arc segment can be shared with the emergency task; if so, keep the original arc segment unchanged; if not, search the entire arc segment to reallocate a suitable arc segment for it; The step S4 comprises: Determine whether all urgent tasks meet hard constraints; Determine whether there is no time overlap between tasks on all antennas; Determine whether there is no time overlap between the tasks on all satellites; The hard constraints include: When all urgent tasks meet the hard constraints, there is no time overlap between tasks on all antennas, and there is no time overlap between tasks on all satellites, the scheduling is determined to be successful and the scheduling plan is output; otherwise, the scheduling fails.

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