  An event-based state estimation approach for reducing communication in a
networked control system is proposed. Multiple distributed
sensor-actuator-agents observe a dynamic process and sporadically exchange
their measurements and inputs over a bus network. Based on these data, each
agent estimates the full state of the dynamic system, which may exhibit
arbitrary inter-agent couplings. Local event-based protocols ensure that data
is transmitted only when necessary to meet a desired estimation accuracy. This
event-based scheme is shown to mimic a centralized Luenberger observer design
up to guaranteed bounds, and stability is proven in the sense of bounded
estimation errors for bounded disturbances. The stability result extends to the
distributed control system that results when the local state estimates are used
for distributed feedback control. Simulation results highlight the benefit of
the event-based approach over classical periodic ones in reducing communication
requirements.
