ESA GNC Conference Papers Repository
Robust Attitude Control Using mu-synthesis for Large Flexible Satellite ETS-VIII
This paper reports results of a preliminary study of an on-orbit advanced robust attitude control experiment using a Japanese large flexible communication satellite: the Engineering Test Satellite VIII (ETS-VIII). The on-orbit attitude control experiment is designed to develop a baseline technology for a class of future large flexible spacecraft and earth observation satellites which require attitude maneuvers using advanced control technology. An important issue is the design of a reduced-order multi-input multi-output (MIMO) robust controller for a linear parameter varying (LPV) spacecraft system. We therefore prepared three control laws after tradeoff studies. Among them, in this paper, a linear time invariant (LTI)-? controller is presented; it is designed parametrically by decomposing the s/c model into control modes and residual modes. In ?-synthesis, the varying parameters are treated as structured uncertainty that is stabilized robustly with unstructured uncertainty by setting the ?-value to less than one. The final controller is LTI-designed through D-K iteration. The candidate experiment controllers were evaluated using preliminary MATLAB-based laboratory design and synthesis and full software simulation of onboard algorithms with emulation of the AOCS hardware. This report presents the outline of this experiment and some spacecraft model features, along with a case study of the proposed method for ETS-VIII and numerical simulation results.