ON DISTURBANCE DECOUPLED OBSERVERS FOR A CLASS OF BILINEAR-SYSTEMS

In this paper, the class of bilinear systems subjected to unknown inpu ts for which there exists a disturbance decoupled observer with linear error dynamics is characterized. It is shown that the design of this kind of observer is equivalent to the design of a disturbance decouple d observer for a linear system. This result simplifies considerably th e observer design compared to those proposed in the literature, and th e observer existence conditions can be easily deduced. As a corollary of this result, necessary and sufficient conditions for the existence of disturbance decoupled linear observers for bilinear systems subject ed to unknown inputs are derived. This approach is extended to the fau lt detection of bilinear systems.