Convex parametrization of reduced order controllers for a class of problems under partial state measurements

We consider a reduced order controller synthesis for a fairly general class of control problems, when some of state variables can be available without noise. We give a necessary and sufficient condition for the existence of a reduced order controller in terms of the linear matrix inequality (LMI), and show that the order of the controller can be reduced by the number of the state variables available in the measurements. In addition, we also provide a convex parametrization of such reduced order controllers