Solution of the disturbance decoupling problem based on fixed poles

When the (almost) disturbance decoupling problem by state feedback is solvable, and under some rather unrestrictive minimality assumption, all the poles of the closed-loop system can simultaneously be placed, except the so-called fixed poles (which are present for any solution). We present here a new approach to solve the (almost) disturbance decoupling problem based on the investigation of fixed poles for some particular cases; moreover, it provides maximal pole assignability while simultaneously solving (almost) disturbance decoupling. It shows that such an approach is strict and effective. Examples are proposed to illustrate our contributions.