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This paper analyses and compares two different attitude representations, using quaternions and modified Rodrigues parameters, in the context of the potential function method applied to autonomously control constrained attitude slew manoeuvres. This method hinges on the definition of novel Lyapunov potential functions in terms of the attitude parameters representing the current attitude, the goal attitude and any pointing constraints, which may be present. It proves to be successful in forcing the satellite to achieve the desired attitude while at the same time avoiding the pointing constraints. A linearised version of the modified Rodrigues parameterisation is also introduced and analysed. Finally advantages and drawbacks of all attitude representations are discussed.

The paper describes the performance of a guidance law based on the Adjoint and SDRE methods in presence of reality representative models of sensors and actuators during the rendezvous phase of the proposed Heracles mission to the Moon. In recent years, the increased interest in returning to the Moon has motivated the necessity to develop accurate models for the analysis of missions that takes into account realistic system components. The paper reviews the mission's details, the rendezvous/berthing guidance algorithm with third body perturbation, and sensor's and actuators state of the art models. A Montecarlo analysis is used to validate the models in order to satisfy the safety of the trajectory. The results show that the proposed guidance and control are capable of maintaining safe relative motion between the vehicles.

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The purpose of this paper is to describe the current activities, results to date, and future activities of the European Space Agency (ESA) Robust AOCS technology program in support to the Phase A of BIOMASS, candidate as Earth Explorer Core Mission 7. Due to the specificity of the chosen BIOMASS configuration this activity is driven by the expected interaction between the large flexible reflector antenna structure and its attitude control system. Currently ESA has developed a technology program to enable the capabilities of integrating the structural sizing and control system design in order to avoid interactions problems. The objective is the development of an Integrated Modeling, Control and Analysis framework IMCA: it incorporates uncertainty modeling via LFT's, robustness analysis via the Structured Singular Value µ and various robust control synthesis techniques such as H ∞ and µ methods. This framework results as natural multivariable extensions of the classical Bode frequency domain techniques. It shall be integrated with a structural design loop into an unified computational framework to exploit control structures interactions in order to increase the spacecraft capabilities, such as better pointing stability, and to improve the overall design when compared to the traditional approach. In the execution of this program two parallel activities will be presented, respectively one by Astrium Limited, UK, and the other by ThalesAlenia Space (TAS), Italy.