For the linear systems with and without uncertainty, two PI controllers are designed. Firstly, while considering
the linear systems without uncertainty, the necessary and sufficient condition for the existence of quadratic dissipative PI
controller of analogous state feedback and static output feedback is derived. And the parametric representation of gains of
PI controller is also given. Then the same problems and similar results for linear systems with uncertainty are considered.
Finally, a numerical example shows the effectiveness of the proposed method.