Robustly stabilizing controllers for dissipative infinite-dimensional systems with collocated actuators and sensors

We derive formulas for normalized doubly coprime factorizations over H 1 , for a class of nonexponentially stabilizable systems. Using these results, we solve the problem of robust stabilization with respect to normalized coprime factor perturbations for a class of innnite-dimensional systems (A; B; B ; D), with nite-rank inputs and outputs and dissipative A; these systems are not exponentially stabilizible We give a parameterization of all controllers which achieve a given robustness margin