Mixed Saturating H2 / H∞ state-feedback design for microsatellite attitude control

The pointing accuracy of microsatellite is vulnerable to space environmental disturbances and the internal uncertainty of moment-of-inertia variation due to its smaller size and weight. The attitude control of microsatellite has been a difficult problem due to the disturbances and uncertainty, as well as the combination of control actuators. The H_∞ control can guarantee the robustness stability against the disturbances and the moment-of-inertia uncertainty, and the H₂ control gives considerations to the rms performance. In this paper the mixed H₂/H_∞ state-feedback controller is designed for attitude controller design of microsatellite. The nonlinear input uncertainty and input saturation is considered, by using linear matrix inequality method, the mixed H₂/H_∞ state-feedback controller is designed, which achieves a balanced performance between H₂ and H_∞ objectives. The simulation results demonstrate that the presented controller is robust and have good steady-state and dynamic performance.