چكيده به لاتين
Engineering issues often require optimal solutions that their object is to minimize the results based on the least available resources. In some cases, issues can be simplified by using defined models that are analytically solved. However, most nonlinear problems require intelligent techniques to find suitable solutions. The purpose of this thesis is to design a constellation orbit consist of imaging satellites to transmit image data to a determined ground station using Inter-Satellite Links (ISL). Therefore, from the communication perspective, the satellite constellation should observe an almost constant target zone in order to achieve real-time imaging by establishing inter-satellite links. To achieve this purpose, the determined ground station needs to be covered daily. In this thesis, the orbit of a satellite constellation is designed using the classic Walker method. Besides, cover analysis is performed to acquire continuous coverage for a determined station. The results illustrate that we can obtain coverage percentage up to 97% by using 36 satellites in 12 orbital planes. Then, an intelligent particle swarm algorithm was utilized to design the satellite constellation orbit to increase the percentage of daily time coverage, reduce the number of gaps, and reduce the maximum time visited the determined ground station. Using this algorithm, the value of two parameters Ω and M play an important role for each satellite orbit to minimize the cost function. The 1.5% increase in the percentage of daily time coverage compared to the Walker method illustrates the desirable performance of the PSO algorithm in the design of satellite orbit parameters. In contrast, in numerical methods of orbit design, each satellite is assigned an orbit plane that leads to increases the cost of the launcher. Indeed, 36 satellites are distributed in 36 orbits. Finally, the Walker Delta method (analytical method) and the particle swarm optimization algorithm (numerical method) have been combined in such a way that the Ω parameter and the mean anomaly parameter (M) of the satellites have been designed using walker method and the particle swarm algorithm respectively. For the satellite constellation consists of 36 satellites distributed in 12 orbital planes, the percentage of daily time coverage of the determined station reaches to 98.5%; moreover, the launch cost was reduced to one-third (reducing 36 orbital planes to 12). As a result, in real-time imaging application, the Walker-PSO combined approach would be appropriate to achieve almost continuous coverage of the determined zone.
