Dynamical orders of decentralized H{infty}; controllers

The problem of decentralized control is addressed, i.e. theproblem of designing a controller where each control input isallowed to use only some of the measurements. It is shown that,for such problems, there does not always exist a sequence ofcontrollers of bounded order which obtains near-optimal control.Neither does there exist an infinite-dimensional optimal controller.Using the insight of the line of proof of these results, a heuristicdesign algorithm is proposed for designing near-optimal controllersof increasing orders.