  In this paper, a synthesis method for distributed estimation is presented,
which is suitable for dealing with large-scale interconnected linear systems
with disturbance. The main feature of the proposed method is that local
estimators only estimate a reduced set of state variables and their complexity
does not increase with the size of the system. Nevertheless, the local
estimators are able to deal with lack of local detectability. Moreover, the
estimators guarantee H-infinity-performance of the estimates with respect to
model and measurement disturbances.
