Ways to achieve the integral control:
q 1. Introduce an
integral in the performance weight We:
z1=We((+PK)-1Wd w.
Now if the norm (2-norm or ¥-norm) between w and z1 is finite, then K must have a pole at s = 0 which is the zero of the sensitivity function.
The standard H2 (or H¥) control theory can not be applied to this problem formulation directly
because the pole of s =0 of We becomes an
uncontrollable pole of the feedback system (A1 is violated).
Suppose We can be factorized as follows