Denilson Paulo Souza dos Santos

Four-Impulsive Rendezvous Maneuvers for Spacecrafts in Circular Orbits Using Genetic Algorithms

Spacecraft maneuvers is a very important topic in aerospace engineering activities today. In a more generic way, a spacecraft maneuver has the objective of transferring a spacecraft from one orbit to another, taking into account some restrictions. In the present paper, the problem of rendezvous is considered. In this type of problem, it is necessary to transfer a spacecraft from one orbit to another, but with the extra constraint of meeting another spacecraft when reaching the final orbit. In particular, the present paper aims to analyze rendezvous maneuvers between two coplanar circular orbits, seeking to perform this transfer with lowest possible fuel consumption, assuming that this problem is time-free and using four burns during the process. The assumption of four burns is used to represent a constraint posed by a real mission. Then, a genetic algorithm is used to solve the problem. After that, a study is made for a maneuver that will make a spacecraft to encounter a planet, in order to make a close approach that will change its energy. Several simulations are presented.

The Study of the Asymmetric Multiple Encounters Problem and Its Application to Obtain Jupiter Gravity Assisted Maneuvers

The Multiple Encounters Problem is described in the literature as the problem of finding trajectories for a spacecraft that leaves from a mother planet, describes a trajectory in the interplanetary space, and then goes back to the mother planet. The present paper extends the literature and the departure and arrival angles of the spacecraft are generalized to be nonsymmetrical. The solutions are shown in terms of the true () and eccentric anomaly (). The velocity variation () required for the transfer is also shown. Then, this study is generalized to consider the possibility that the spacecraft makes a close approach with the mother planet to change its energy in the return trip. The velocity () and energy variation () due to this passage are obtained. The topics studied here can be applied in missions that leave and come back to the Earth, with the goal of studying the interplanetary space, as well as for missions whose objective is to make an alteration in the energy of the space vehicle through a swing-by with the mother body.

RENDEZVOUS MANEUVERS USING GENETIC ALGORITHM

The goal of the present paper is to study orbital coplanar maneuvers between circular orbits. The control available to perform this maneuver is the application of several impulses. The solutions has searched that minimize the total variation of velocity that has to be used to implement the impulses calculated by the algorithms. The transfer time has obtained, but it isn’t considered as an optimization parameter. A genetic algorithm is used to solve the problem, combined with the Lambert´s Problem associated with those transfers. With the goal of making comparisons, a numerical algorithm has developed to solve the same transfers, but considering a low thrust maneuver. A propulsion system provides large savings in consumption, but with an expense of longer maneuvers.

Rendezvous maneuvers using Genetic Algorithm

The present paper has the goal of studying orbital maneuvers of Rendezvous, that is an orbital transfer where a spacecraft has to change its orbit to meet with another spacecraft that is travelling in another orbit. This transfer will be accomplished by using a multi-impulsive control. A genetic algorithm is used to find the transfers that have minimum fuel consumption.

Three-dimensional Two-Body Tether System — Equilibrium Solutions

The tethered spacecraft system was studied. This is a three-body problem formed by the main body with larger mass, m1 and m2 are the smaller bodies and they are connected by a cable. The main body is orbited by the center of mass m1 and m2. The cable was assumed rigid and massless. The study goal is analyze the existing equilibrium to tether in two situations: using a control law for the cable size and constant cable size. Assuming a control law, the solutions were fixed values independent of eccentricity (e) and true anomaly (v) of the system. For the constant case there are periodic solutions, continuous and discontinuous for different values of e and v. The results obtained are angles functions which describe the m1 and m2 plane and out plane motion.

MODULARIDADE E DESEMPENHO COMPUTACIONAL DE ALGORITMOS GENÉTICOS

Algoritmos Geneticos sao metodos heuristicos de busca de solucoes otimas para funcoes, dentro de um espaco de busca determinado, aplicando metodos que se baseiam na teoria da evolucao de Darwin. Possiveis solucoes para a funcao, a qual se deseja obter a melhor solucao sao tomadas como individuos, os quais em conjunto formam uma populacao. Aplicando metodos de cruzamento e mutacao entre os individuos mais aptos, melhor aptidao na funcao(oes), a populacao evolui tendendo a sempre produzir melhores individuos que, por sua vez, sao melhores solucoes para o problema envolvido.

ESTUDO DE TRANSFERÊNCIAS ORBITAIS UTILIZANDO ALGORITMO GENÉTICO

A realizacao de transferencias orbitais por meio de sistemas propulsivos em um campo de forca central Newtoniano consiste em um problema de fundamental importância no estudo da mecânica celeste e na concepcao de missoes espaciais baseadas em satelites artificiais, tendo sido tema de diversos estudos. A transferencia torna-se necessaria quando ocorrem desvios nos parâmetros orbitais do satelite, fazendo com que ele se encontre em uma orbita diferente da nominal, podendo ainda estar prevista na propria missao [1].