Direct approach to almost disturbance and almost input-output decoupling

A direct solution to the almost input-output and disturbance decoupling problem is given. The approach is based on a new canonical form for linear systems—which is obtained in a fully constructive way—together with some elementary approximation results. The solution is given in the form of an explicit feedback law, parameterized by a scalar e. By letting e go to zero, the accuracy of the resulting approximate solution can be improved to any desired degree.