Mixed H₂/H_⊥ state-feedback design for microsatellite attitude control

Owing to a great decrease in size and weight, the pointing accuracy of microsatellite is vulnerable to space environmental disturbances and the internal uncertainty of moment-of-inertia variation. Mixed H₂/H∞ control, giving consideration to both stability robustness and root-mean-square (rms) performance, is particularly attractive for attitude controller design of microsatellites. By using linear matrix inequality method, the numerical solution of mixed H₂/H∞ state-feedback controller can be efficiently solved. The performance differences between mixed H₂/H∞ controller and its two extremes-pure H₂ controller and pure H∞ controller - are discussed in detail. Mixed H₂/H∞ controller shows the remarkable capability of achieving a balanced compromise between H₂ and H∞ performances.