Resumo (PT):
Abstract (EN):
The asymptotic behaviour of a nonlinear continuous
time approximate filter when the variance of the observation noise tends to 0 is investigated. We consider a
particular class of signals modeled by a two-dimensional
quasi-linear diffusion from which only one of the components is noisy, and we assume that a one-dimensional
linear function of the signal, depending only of the unnoisy component, is observed in a low noise channel.
Under some detectability assumptions the unobserved
signal can be restored by means of an approximate nonlinear filter. We establish that the filtering error converges to 0 and we give an upper bound for the convergence rate. The efficiency of the approximate filter is
compared with the efficiency of the optimal filter and
the order of magnitude of the error between the two filters, as the observation noise vanishes, is obtained. A
more general case is briefly presented.
Language:
English
Type (Professor's evaluation):
Scientific
No. of pages:
3