On Disturbance Decoupled Observers for Linear Descriptor Systems 1

Conditions for the existence of disturbance decoupled minimal-order observers for a class of descriptor systems are presented. Basically, these conditions are associated to the solution of a generalized Sylvester equation under a constraint that describes the disturbance decoupling of the estimated state. Thus, under some structural conditions of the considered descriptor system, a sequence of coordinate transformation allows to define a reduced-order normal system. Both eigenstructure assignment and regional pole placement techniques can be applied to solve the constrained reduced-order Sylvester equation. For regional pole placement, a LMI technique is proposed and a illustrative numerical example i reported.