Graph colouring approaches for a satellite range scheduling problem

A goal of this paper is to efficiently adapt the best ingredients of the graph colouring techniques to an NP-hard satellite range scheduling problem, called MuRRSP. We propose two new heuristics for the MuRRSP, where as many jobs as possible have to be scheduled on several resources, while respecting time and capacity constraints. In the permutation solution space, which is widely used by other researchers, a solution is represented by a permutation of the jobs, and a schedule builder is needed to generate and evaluate a feasible schedule from the permutation. On the contrary, our heuristics are based on the solution space which contains all the feasible schedules. Based on the similarities between the graph colouring problem and the MuRRSP, we show that the latter solution space has significant advantages. A tabu search and an adaptive memory algorithms are designed to tackle the MuRRSP. These heuristics are derived from efficient graph colouring methods. Numerical experiments, performed on large, realistic, and challenging instances, showed that our heuristics are very competitive, robust, and outperform algorithms based on the permutation solution spac

Genetic algorithms for satellite scheduling problems

Recently there has been a growing interest in mission operations scheduling problem. The problem, in a variety of formulations, arises in management of satellite/space missions requiring efficient allocation of user requests to make possible the communication between operations teams and spacecraft systems. Not only large space agencies, such as ESA (European Space Agency) and NASA, but also smaller research institutions and universities can establish nowadays their satellite mission, and thus need intelligent systems to automate the allocation of ground station services to space missions. In this paper, we present some relevant formulations of the satellite scheduling viewed as a family of problems and identify various forms of optimization objectives. The main complexities, due highly constrained nature, windows accessibility and visibility, multi-objectives and conflicting objectives are examined. Then, we discuss the resolution of the problem through different heuristic methods. In particular, we focus on the version of ground station scheduling, for which we present computational results obtained with Genetic Algorithms using the STK simulation toolkit.Peer ReviewedPostprint (published version

Satellite downlink scheduling problem: A case study

The synthetic aperture radar (SAR) technology enables satellites to efficiently acquire high quality images of the Earth surface. This generates significant communication traffic from the satellite to the ground stations, and, thus, image downlinking often becomes the bottleneck in the efficiency of the whole system. In this paper we address the downlink scheduling problem for Canada's Earth observing SAR satellite, RADARSAT-2. Being an applied problem, downlink scheduling is characterised with a number of constraints that make it difficult not only to optimise the schedule but even to produce a feasible solution. We propose a fast schedule generation procedure that abstracts the problem specific constraints and provides a simple interface to optimisation algorithms. By comparing empirically several standard meta-heuristics applied to the problem, we select the most suitable one and show that it is clearly superior to the approach currently in use.Comment: 23 page

Resolución de conflictos en la programación de actividades de sistemas productivos utilizando coloración de grafos

En este artículo se expone un método formal para la programación de actividades que presentan conflictos por utilización simultánea de recursos. Se muestra como mediante la construcción del modelo de un sistema productivo usando grafos y la posterior aplicación de un método de coloreo de nodos, es posible elaborar una programación de tareas que pueden ser llevadas a cabo sin impedimentos. El método presentado se ilustra mediante un ejemplo representativo de las tareas de mantenimiento de un sistema mecánico, igualmente se presenta un algoritmo que permite optimizar el número de iteraciones necesarias para el coloreo de nodos de un grafo

Contact Automation For The ESTCube-2 Mission Control System

ESTCube-2 on Eesti Tudengisatelliidi Sihtasutuse satelliidi programm, mille eesmärgiks on tehnoloogiline testimine järgmiste missioonide tarbeks. Peale satelliidi orbiidile saatmist toimub suhtlemine satelliidiga maapealsete sidejaamade abil, aga kontakti aeg satelliidiga ühest maapealsest sidejaamast on väga limiteeritud . Käesoleva töö eesmärk on disainida ja implementeerida kontakti automatiseerimise tarkvaramoodul, mis võimaldab minimaalse inimese sekkumisega planeerida ja läbi viia kontakte satelliitidega. Esmane funktsioneeriv tarkvaramoodul on loodud autori poolt. Töös selgitatakse tarkvara disaini ja implementatsiooni ning ühildamist olemasoleva missioonijuhtimissüstemiga, mis on kombinatsioon tark- ja riistvarast, mille abil jälgitakse ja juhitakse orbiidil olevat satelliiti.ESTCube-2 is the first student satellite project of the Estonian Student Satellite Foundation and it's objective is the technological demonstration of scientific payloads for upcoming missions. After a satellite's launch, the communication can be done through ground stations, but the contact time is very short over a limited area at a given point in time over the earth. The aim of this thesis is to design and implement a contact automation module which can schedule and execute automatic contacts with the satellite without minimal/no human intervention. The author aims to implement the first functional version of the required software module. This thesis explains the thought process, design and implementation of the software module, including the integration with the existing ESTCube Mission Control System—a combination of software and hardware that is used for monitoring and controlling the satellite after launch