We address the multi-satellite scheduling problem with limited observation capacities that arises from the need to observe a set of targets on the Earth's surface using imaging resources installed on a set of satellites. We define and analyze the conflict indicators of all available visible time windows of missions, as well as the feasible time intervals of resources. The problem is then formulated as a mixed integer linear programming model, in which constraints are derived from a careful analysis of the interdependency between feasible time intervals that are eligible for observations. We apply the proposed model to several different problem instances that reflect real-world situations. The computational results verify that our approach is effective for obtaining optimum solutions or solutions with a very good quality.
This paper describes three approaches to assigning tasks to earth observing satellites EOS. A fast and simple priority dispatch method is described and shown to produce acceptable schedules most of the time. A look ahead algorithm is then introduced that outperforms the dispatcher by about 12 with only a small increase in run time. These algorithms set the stage for the introduction of a genetic algorithm that uses job permutations as the population. The genetic approach presented here is novel in that it uses two additional binary variables, one to allow the dispatcher to occasionally skip a job in the queue and another to allow the dispatcher to occasionally allocate the worst position to the job. These variables are included in the recombination step in a natural way. The resulting schedules improve on the look ahead by as much as 15 at times and 3 on average. We define and use the "window-constrained packing" problem to model the bare bones of the EOS scheduling problem. Abstract Agile satellites belong to the new generation of satellites with three degrees of freedom for acquiring images on the Earth. As a result, they have longer visible time windows for the requested targets. An image shot can be conducted at any time in the window if and only if the time left is sufficient for the fulfillment of the imaging process. For an agile satellite, a different observation time means a different image angle, thus defining a different transition time from its neighboring tasks. Therefore, the setup time for each imaging process depends on the selection of its observation start time, making the problem a time-dependent scheduling problem. To solve it, we develop a metaheuristic, called adaptive large neighborhood search (ALNS), thus creating a conflict-free observational timeline. ALNS is a local search framework in which a number of simple operators compete to modify the current solution. In our ALNS implementation, we define six removal operators and three insertion operators. At each iteration, a pair of operators is selected to destroy the current solution and generate a new solution with a large collection of variables modified. Time slacks are introduced to confine the propagation of the time-dependent constraint of transition time. Computational experiments show that the ALNS metaheuristic performs effectively, fulfilling more tasks with a good robustness. Earth Observation Satellite (EOS) scheduling is an important oversubscribed constraint optimization problem. Permutation-based scheduling methods have recently been shown to be effective on these problems. However, the new agile EOS satellites present additional scheduling complexity because they allow image acquisition over a window of possible observation times. Constraint propagation algorithms have been successfully applied in traditional local search methods for these problems. In this paper, we describe a synthesis of permutation-based search and constraint propagation for agile EOS scheduling. Our approach incorporates the advantages of both techniques. We obtain the large neighbourhood behaviour of permutation search for oversubscribed resource scheduling problems. As well, we exploit the power of constraint propagation to retain as much flexibility as possible while building the schedule. We investigate different local optimization algorithms (including hill-climbing, simulated annealing and squeaky wheel optimization) coupled with constraint propagation over image acquisition time windows. We compare our method to recent permutation-based methods for non-agile EOS scheduling which rely upon a greedy scheduler for assigning image acquisition times. Experiments are performed on synthetic EOS data sets using both uniform random image targets and actual urban image target sets. We measure both schedule quality and solution degradation as new image requests are added dynamically to the problem. Our results suggest that permutation-based search coupled with constraint propagation works very well for agile EOS scheduling. Abstract This article concerns the problem of managing the new generation of Agile Earth Observing Satellites (AEOS). This kind of satellites is presently studied by the French Centre National d'Etudes Spatiales (PLEIADES project). The mission of an Earth Observing Satellite is to acquire images of specified areas on the Earth surface, in response to observation requests from customers. Whereas non-agile satellites such as SPOT5 have only one degree of freedom for acquiring images, the new generation satellites have three, giving opportunities for a more efficient use of the satellite imaging capabilities. Counterwise to this advantage, the selection and scheduling of observations becomes significantly more difficult, due to the larger search space for potential solutions. Hence, selecting and scheduling observations of agile satellites is a highly combinatorial problem. This article sets out the overall problem and analyses its difficulties. Then it presents different methods which have been investigated in order to solve a simplified version of the complete problem: a greedy algorithm, a dynamic programming algorithm, a constraint programming approach and a local search method. This paper studies an image collection planning problem for a Korean satellite, KOMPSAT-2 (KOrea Multi-Purpose SATellite-2). KOMPSAT-2 has the mission goal of maximizing image acquisition in time and quality requested by customers and operates under several complicating conditions. One of the characteristics in KOMPSAT-2 is its strip mode operation, in which segments of continuous-observation areas with known sizes are captured one at a time. In this paper, we regard the segment as a group of adjoining geographical square regions (scenes), whose size must also be determined. Thus, the problem involves the determination of proper segment lengths as well as an image collection schedule. We present a binary integer programming model for this problem in a multi-orbit long-term planning environment and provide a heuristic solution approach based on the Lagrangian relaxation and subgradient methods. We also present the results of our computational experiment based on randomly generated data.