Robustness analysis of attitude and orbit control systems for flexible satellites

In this study, an optimisation-based approach is proposed for the robustness analysis of an attitude and orbit control system (AOCS) for flexible satellites. Several optimisation methods, including local gradient-based algorithms, global evolutionary algorithms and hybrid local/global algorithms are applied to the problem of analysing the robustness of a full-authority multivariable controller with respect to several frequency and time domain performance criteria, for a 6 degree of freedom simulation model of a satellite with large sun shields. The results of our study reveal the advantages of optimisation-based worst-case analysis over traditional Monte Carlo simulations for systems with flexible dynamics. In particular, it is shown that frequency domain analysis can provide useful guidance for the formulation of subsequent time domain tests, and that hybrid local/global optimisation algorithms can produce more reliable estimates of worst-case performance, while also reducing the associated computational overheads. The proposed approach appears to have significant potential for improving the industrial flight clearance process for next-generation high-performance satellite control systems.