OUTPUT-FEEDBACK DISTURBANCE DECOUPLING IN NONLINEAR-SYSTEMS

The problem of disturbance decoupling by means of output feedback is a ddressed. The notion of conditioned invariance is reconsidered in a li near algebraic framework. Using this geometric notion, a necessary and sufficient condition (respectively, necessary condition) is obtained for solving the disturbance decoupling problem by quasistatic output f eedback (QDDPO) (respectively, the disturbance decoupling problem by d ynamic output feedback (DDDPO). The necessary conditions for DDDPO whi ch are derived are weaker than the existing ones. A sufficient conditi on for the disturbance decoupling problem by static output feedback (D DPO) is given as well.