A behavioral approach to H2 optimal control

In this paper we consider a formulation oftl~ H2 optimal controlproblem in which the controller is not viewed as an operator thattransforms measurements to controls. Instead, the controller isassumed to be a device that constrains a set of a-priori specified interconnection variables so as to achieve a controlled systemwhose manifest vari~ - ave a free component and satisfyan upperbound on th £2 norm of its impulse response. We formalize and solve this problem in a behavioral setting, that is,without reference to system representa nd input-outputstructures. TI ivalance between th H2 control problem, the generalize H2 control problem and the LQ optimal controlproblem are established