Observability of nonlinear differential algebraic systems

Abstract

We define the smooth observability of nonlinear DAE systems and give sufficient conditions for this property to hold locally in a neighborhood of a solution. The matrix rank conditions for observability are verifiable by a combination of symbolic and numerical linear algebra computations. These conditions generalize conditions that have appeared in the literature for observability of linear time-varying DAE systems. We indicate how the main result is potentially useful in studying a system's zero dynamics. Some relevant rank properties of Hessenberg DAE systems are established.