Passive IR-UWB Localization System for UAV-Based Electric Facility Inspection During GPS Outage

A practical localization system is proposed for an unmanned aerial vehicle (UAV) performing its inspection mission under the global positioning system (GPS) signal blockage. The sensor hardware consists of a single transmitter and a cruciform receiver array, which produces the range difference (RD) information for UAV positioning. Our sensor is based on the impulse-radio ultra wide-band (IR-UWB) technology; hence it is robust to RF interference due to exogeneous electromagnetic fields from electric facilities. With this sensor configuration, UAV localization problem is formulated as state estimation for an uncertain linear measurement model, which can be solved by using the robust weighted least squares (RWLS) estimator. To cope with the performance degradation of the RWLS estimator due to the imperfect prior knowledge of the measurement noise statistics, a geometric constraint expressed by the UAV state variables is exploited to compensate the localization errors. Through experimental results, it is verified that the proposed solution provides satisfactory UAV positioning performance and secures the reliability of the localization system in practice.