Accuracy analysis of short-range Doppler shift target localization using a multi-sensor platform

Doppler-based target localization leads to a state estimation problem involving a nonlinear measurement equation. Finding the unique solution for this problem becomes even more challenging, if the sensor arrangement is unfavorable. This may happen due to spatial restrictions or other limitations and requirements of the underlying application. In this contribution, we consider different configurations of closely arranged, mutually incoherent radar sensors as they are typically used for short-range target detection and localization. Potential applications arise e.g. in automotive and industrial surveillance where sensors are arranged straight-line, with uniform spacing, or within a small-sized area. The problem of observability in such systems is discussed. Furthermore, the metrics of Fisher Information and Cramer-Rao Lower Bound (CRLB) as used in nonlinear systems, such as Doppler radars, are evaluated to particularize theoretical limits on localization accuracy. Basic sensor-Target-geometries are considered and their influence on finding the correct solution in Doppler-only applications is investigated. The performance limits for different uniform linear arrays (ULAs) are evaluated by simulations. Results for a single-Target multi-sensor scenario in two-dimensional space are given and improvements, achieved by modification of the ULA, are discussed.