Research on unobservability problem for two-dimensional bearings-only target motion analysis

The observability for bearings-only target motion analysis is a very important problem. The bearings-only system is to be said observable if and only if the target motion parameters can be uniquely determined by noise-free bearing measurements. The problem of unobservability for hearing-only target tracking system is discussed in this paper based on the target that travels in the 2-dimentional space with a constant acceleration. Utilizing Gramm rule and rank of matrix, a new proposition that the bearing-only locating and tracking system remains unsolvable prior to an observer maneuver is presented and proved. By proving the proposition, it is shown that for certain type of observer movement the estimation process remains unobservable, even if the target moves with a constant accelerate. The work done in this paper is a valuable study in solving the bearings-only target motion analysis.