| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 2.92 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
A transferência orbital é um elemento indispensável para qualquer missão espacial. Missões
como a reparação, manutenção, intercessão, montagem de estruturas em grande escala ou
formação de redes de satélites dependem diretamente do sucesso da transferência orbital que
lhes está associada. Durante os últimos anos, o problema da transferência orbital tem sido
abordado como parte do problema de rendezvous e raramente como um problema isolado.
O foco desta dissertação é a elaboração de um controlador robusto H8 para ser aplicado no
problema de transferência orbital entre duas órbitas não coplanares onde são consideradas
perturbações externas e limitações nos atuadores.
Inicialmente vai ser definido o modelo dinâmico utilizado para descrever o movimento relativo do veículo espacial na órbita de transferência. Existem dois modelos dinâmicos que
podem ser utilizados que são as equações de Hill-Clohessy-Wiltshire (C-W) e as equações de
Tschauner-Hempel (T-H). O modelo escolhido foi as equações T-H que permitem uma excentricidade da órbita arbitrária mas que só são válidas quando o veículo está na vizinhança
da órbita. De seguida, é apresentado o modelo utilizado para determinar a trajetória de transferência, nomeadamente o Problema de Lambert, e os diversos elementos matemáticos que
são necessários para fazer a conexão entre o modelo dinâmico e a trajetória de transferência.
Nos capítulos seguintes, é apresentado o modelo matemático para a elaboração do controlador robusto H8 bem como a sua implementação em dois exemplos práticos. Os resultados
obtidos nos exemplos práticos são bastante satisfatórios tendo em conta as características
do modelo implementado. Ou seja, o controlador desenvolvido apresenta robustez para ser
aplicado em movimentos de transferência orbital.
Orbital transfer is an indispensable element for any space mission. Missions such as repair, maintenance, intersection, large-scale structure assembly, and satellite network formation depend directly on the success of the associated orbital transfer. During the last few years, the orbital transfer problem has been addressed as part of the rendezvous problem and rarely as a stand-alone problem. This dissertation focuses on the development of a robust H8 controller to be applied to the orbital transfer problem between two non-coplanar orbits where external perturbations and actuator constraints are considered. Initially, the dynamic model used to describe the relative motion of the spacecraft in the transfer orbit will be defined. There are two dynamic models that can be used which are the Hill-Clohessy-Wiltshire (C-W) equations and the Tschauner-Hempel (T-H) equations. The model chosen was the T-H equations that allow an arbitrary eccentricity of the orbit but are only valid when the vehicle is in the vicinity of the orbit. Next, the model used to determine the transfer path, namely the Lambert Problem, and the various mathematical elements that are needed to make the connection between the dynamic model and the transfer path are presented. In the following chapters, the mathematical model for the elaboration of the robust controller H8 is presented as well as its implementation in two practical examples. The results obtained in the practical examples are quite satisfactory considering the characteristics of the implemented model. That is, the developed controller presents robustness to be applied in orbital transfer movements.
Orbital transfer is an indispensable element for any space mission. Missions such as repair, maintenance, intersection, large-scale structure assembly, and satellite network formation depend directly on the success of the associated orbital transfer. During the last few years, the orbital transfer problem has been addressed as part of the rendezvous problem and rarely as a stand-alone problem. This dissertation focuses on the development of a robust H8 controller to be applied to the orbital transfer problem between two non-coplanar orbits where external perturbations and actuator constraints are considered. Initially, the dynamic model used to describe the relative motion of the spacecraft in the transfer orbit will be defined. There are two dynamic models that can be used which are the Hill-Clohessy-Wiltshire (C-W) equations and the Tschauner-Hempel (T-H) equations. The model chosen was the T-H equations that allow an arbitrary eccentricity of the orbit but are only valid when the vehicle is in the vicinity of the orbit. Next, the model used to determine the transfer path, namely the Lambert Problem, and the various mathematical elements that are needed to make the connection between the dynamic model and the transfer path are presented. In the following chapters, the mathematical model for the elaboration of the robust controller H8 is presented as well as its implementation in two practical examples. The results obtained in the practical examples are quite satisfactory considering the characteristics of the implemented model. That is, the developed controller presents robustness to be applied in orbital transfer movements.
Description
Keywords
Controlador Robusto H8 Equações de Tschauner-Hempel (T-H) Problema de Lambert Transferência Orbital