Complexity and Scalability of Hierarchical Control for Networked Infrastructures

Abstract

When it comes to controlling large systems, such as networked infrastructure systems (roads, the electricity network, data communications networks, etc.), hierarchical control (HC) is among the most often used options. Yet, HC is still not very well understood and its applications are primarily human oriented, not automated. Several knowledge gaps limit its automated application, even in cases where this would offer considerable societal benefits, for instance, for the congestion problem in road traffic. HC is first of all a way to reduce complexity in the control of large systems. If this works well, the control becomes scalable and the controlled systems can have virtually any size. This chapter proposes a way to do this complexity reduction with HC in cases that involve a high level of automation. It introduces a number of key notions for HC and lists requirements for its applicability. A subsequent chapter will show how these requirements can be fulfilled for the application of HC to the management of road traffic.