Structured optimal control with applications to network flow coordination

In this paper the design of controllers that incorporate structural and multiobjective performance requirements is considered. The control structures under study cover nested, chained, hierarchical, delayed interaction and communications, and symmetric systems. Such structures are strongly related to several modern-day and future applications including integrated flight propulsion systems, platoons of vehicles, micro-electromechanical systems, networked control, control of networks, production lines and chemical processes. It is shown that the system classes presented have the common feature that all stabilizing controllers can be characterized by convex constraints on the Youla-Kucera parameter. Using this feature, a solution to a general optimal performance problem that incorporates time domain and frequency domain constraints is obtained. A synthesis procedure is provided which, at every step, yields a feasible controller together with a measure of its performance with respect to the optimal performance. Convergence to the optimal performance is established. An example of a multi-node network congestion control problem is provided that illustrates the effectiveness of the developed methodology.