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This paper presents the modeling and robust H ∞ control of a novel ultra-quiet spacecraft which employs the non-contact Stewart platform to actively control its support module (SM) and payload module (PM). The SM and PM are mechanically separated such that the disturbances and vibrations from the SM can be perfectly suppressed. However, this novel spacecraft has internal instability. To overcome the instability, this paper derives the dynamics model of the non-contact Stewart spacecraft using Newton–Euler approach at first. Then, the mixed sensitivity robust H ∞ control is developed to guarantee both the attitude stability and precision pointing. Finally, simulation studies are provided to validate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

In the last few years, the observation of gravitational waves by means of LIGO and Virgo interferometers and the success of LISA Pathfinder, gave a significant boost to the development of space-based gravitational wave observatories. The European Space Agency confirmed LISA as the third large class mission of the Cosmic Vision program. The present work is part of the Drag Free and Attitude Control System (DFACS) preliminary prototyping study, which aims at the development of mathematical models and advanced controllers for the science phases of the LISA mission. Nonlinear modelling is a fundamental step for the derivation of linearized and decoupled models as well as for the development of suitable linear and nonlinear controllers. In this paper, an analytical nonlinear model is derived, which describes all the relevant dynamics of a LISA spacecraft, representing an effective compromise between accuracy and complexity. The model is extensively validated through linearization analysis and Monte Carlo simulations. [ABSTRACT FROM AUTHOR]