Multi satellites scheduling algorithm based on task merging mechanism

摘要

Earth observation satellites are platforms equipped with optical instruments that orbit the earth to take photographs of specific areas at users’ requests. Compared with huge user requests, satellites are still scanty resources. For some task, the satellite has to roll its camera to take the desired image. However,manysatellites are rigidly restricted on maneuverability. As a result, the performances of satellites are greatly confined. Therefore, we need a scientific observation plan to weaken the constraints arising from satellites’ poor slew ability. To solve the problem we present a multi satellites scheduling algorithm based on task merging mechanism. The algorithm partitions the problem into two sub-problems: task assignment and task merging. In task assignment, we propose an adaptive ant colony optimization algorithm to select specific time window for each task, creating a task list for each satellite. In task merging, we propose the concept of task combination and develop a dynamic programming algorithm to find the best merging plan for each satellite. The two sub-problems are logically coupled; a valid observation plan will be got after much iteration. Finally, a series of test examples are given out, which demonstrate our algorithm to be effective.