Multi-objective output-feedback control for microsatellite attitude control: An LMI approach

Abstract

Mixed H 2 / H ∞ output-feedback controller with pole placement constraints against the internal uncertainty of moment-of-inertia variation and space environmental disturbances is proposed for mircosatellite attitude control. The multi-objective controller is designed based on linear model of attitude dynamics. The H ∞ performance takes into account both robustness stability against moments-of-inertia uncertainty and the disturbance rejection aspect. H 2 performance takes into account the LQG aspect which avoids the undesirable wheels’ saturation effect. In addition, the closed-loop poles can be forced into some sector of the stable half-plane to obtain well-damped transient responses. The problem is then reduced to a convex optimization involving linear matrix inequalities (LMIs), so it can be efficiently solved. The simulation results demonstrate that the presented mixed H 2 / H ∞ control system is robust stable and optimal in the sense of H 2 norm, and has good steady-state and dynamic performances against the parameter uncertainties and various disturbances for the microsatellite attitude control system.