  We investigate the scenario where a perturbed nonlinear system transmits its
output measurements to a remote observer via a packet-based communication
network. The sensors are grouped into N nodes and each of these nodes decides
when its measured data is transmitted over the network independently. The
objective is to design both the observer and the local transmission policies in
order to obtain accurate state estimates, while only sporadically using the
communication network. In particular, given a general nonlinear observer
designed in continuous-time satisfying an input-to-state stability property, we
explain how to systematically design a dynamic event-triggering rule for each
sensor node that avoids the use of a copy of the observer, thereby keeping
local calculation simple. We prove the practical convergence property of the
estimation error to the origin and we show that there exists a uniform strictly
positive minimum inter-event time for each local triggering rule under mild
conditions on the plant. The efficiency of the proposed techniques is
illustrated on a numerical case study of a flexible robotic arm.
