Observability-Based Selection Criterion for Anchor Nodes in Multiple-Cell Localization

The coverage of localization systems for a mobile robot can be expanded by using a multiple-cell structure. In such a structure, there are a number of anchor nodes installed at several positions whose coordinates are known in advance. Therefore, the mobile robot must select some anchor nodes that are suitable for its localization. As a selection criterion for these anchor nodes, the strength of the received ranging signal has been used in the conventional manner, but this approach is highly dependent on the particular environment. In this paper, we focus on the recently proposed localization model for biased chirp spread spectrum ranging. To apply the model to multiple-cell localization, we propose a selection criterion for anchor nodes that is based upon the observability of the model. The proposed criterion assures that the estimated coordinates by the extended Kalman filter can track the actual position of the mobile robot when it is located at the boundary of two adjacent cells.