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Mathematical Problems in Engineering
Volume 2014 (2014), Article ID 234928, 11 pages
http://dx.doi.org/10.1155/2014/234928
Research Article

Heuristic Scheduling Algorithm Oriented Dynamic Tasks for Imaging Satellites

1School of Computer, China University of Geosciences, Wuhan 430074, China
2Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, UK

Received 4 March 2014; Revised 13 June 2014; Accepted 13 June 2014; Published 17 July 2014

Academic Editor: Yi Chen

Copyright © 2014 Maocai Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Imaging satellite scheduling is an NP-hard problem with many complex constraints. This paper researches the scheduling problem for dynamic tasks oriented to some emergency cases. After the dynamic properties of satellite scheduling were analyzed, the optimization model is proposed in this paper. Based on the model, two heuristic algorithms are proposed to solve the problem. The first heuristic algorithm arranges new tasks by inserting or deleting them, then inserting them repeatedly according to the priority from low to high, which is named IDI algorithm. The second one called ISDR adopts four steps: insert directly, insert by shifting, insert by deleting, and reinsert the tasks deleted. Moreover, two heuristic factors, congestion degree of a time window and the overlapping degree of a task, are employed to improve the algorithm’s performance. Finally, a case is given to test the algorithms. The results show that the IDI algorithm is better than ISDR from the running time point of view while ISDR algorithm with heuristic factors is more effective with regard to algorithm performance. Moreover, the results also show that our method has good performance for the larger size of the dynamic tasks in comparison with the other two methods.