Observability Analysis of Deep-space Autonomous Navigation System

Checking the observability is important. It is a way to evaluate the feasibility of the system such that the measurement set can enable reliable state estimation. In this paper, the concept of local observability is introduced for nonlinear systems. Here two kinds of method to check the observability of a deep-space autonomous navigation system are used: an analytical method and a computational method. The first method takes partial derivative of the measurement. The observability matrix is used to determining local observability in the other method. The condition number of the matrix is adopted as a scalar measure of degree of local observability. At last we give the observability results of an interplanetary spacecraft navigation system.