Digital communication technology is increasingly used in control applications. The properties of wireless communication channels such as information loss, time delays and limited band width easily come into conflict with the typical reliability and security standards in control processes. This has led to the development of a very active research field.
The focus of our work lies in the modeling and analysis of the dynamics generated by communication protocols such as the internet protocol TCP and particular communication protocols used in control. At the same time, we develop methods for the design of controllers which meet the requirements of digital communication channels. Networked control systems violate the assumption of classical control theory that information in feedback loops can be transmitted instantaneously, lossless and with arbitrary precision. Mathematical models of digital communication and control networks have to take into account general communication constraints, time-delayed transmissions, partial loss of information and variable network topologies. Examples can be found, for instance, in telerobotics, traffic control and the control of unmanned vehicles.
Our work has used nonlinear small-gain concepts - developed in the framework provided by the theory of input-to-state stability - to derive stabilizing controllers in the presence of uncertain communication channels. Recently, intermittent, low bandwidth control has been investigated in the context of distributed optimization problems.