An optimal geometric solution of almost disturbance decoupling via state feedback with pole placement

When the almost disturbance decoupling problem by state feedback is solvable, in any solutions are present some fixed poles and infinite poles in the closed loop system, which cannot be freely assigned. An optimal geometric solution with maximal pole placement can be achieved. We present here a new approach to achieve the optimal geometric solution, and the accurate expression of the optimal geometric solution is given. An example is proposed to illustrate our contributions.