H/sub /spl infin//-almost disturbance decoupling with internal stability for linear systems subject to input saturation

For a linear system subject to input saturation and input-additive disturbances, we show that: (1) the H/sub /spl infin//-almost disturbance decoupling problem with local asymptotic stability is always solvable via state feedback as long as the system in the absence of saturation is stabilizable, no matter where the open-loop poles are; and (2) the H/sub /spl infin//-almost disturbance decoupling problem with semiglobal asymptotic stability is solvable via state feedback as long as the system in the absence of saturation is stabilizable with all its open-loop poles located in the closed left-half plane. The results generalize those in Lin et al. (1996) by not requiring the disturbance to be bounded by a known bound, or even bounded.