Distributed event-based control of physically interconnected systems

This paper investigates event-based control of systems that are composed of physically interconnected subsystems. The event-based controller consists of a control input generator and an event generator. The main aim for the design of these components is (i) to approximate the behavior of a continuous state-feedback control by the event-based control with adjustable accuracy and (ii) to reduce the feedback communication compared to a decentralized event-based control approach proposed in literature. In the event-based control loop i, the triggering of events is caused by the coupling input to subsystem i. The proposed event-based control approach diminishes the influence of these interconnections by using an approximate model, which estimates the behavior of the neighbors of subsystem i, for the control input generation. Events are triggered based on two different conditions: The first one causes a transmission of the current subsystem state locally from event generator i to control input generator i. The second type of event is triggered whenever the state of the approximate model needs to be reset. This brings up a new kind of event-based control where the event generator i requests current state information from the neighbors of subsystem i. The event-based controller works in a distributed manner, because it uses both local state information as well as information from neighbor systems. It is shown that the deviation between the behavior of the continuous and the event-based control system depends upon the parameter of the first triggering condition only, whereas the minimum inter-event times can be adjusted by means of the parameter of the second triggering condition.