  In this paper, linear and nonlinear event-triggered extended state observers
are designed for a class of uncertain stochastic systems driven by bounded and
colored noises. Two event-generators with an ensured positive minimum
inter-event time for every sample path solution of the stochastic systems, are
proposed for the designs of linear and nonlinear event-triggered extended state
observers, respectively. The mean square and almost sure convergence of the
estimation errors of unmeasured state and stochastic total disturbance
including internal uncertainty and external stochastic noises is presented with
rigorous theoretical proofs. Compared with the linear event-triggered extended
state observer, the theoretical results show that the nonlinear one via
homogeneity possesses higher estimation accuracy but is at the price of higher
triggering frequency. Some numerical simulations are performed to authenticate
the theoretical results.
