Observation-augmented EKF Based Local 3-D Localization Method for Moving Target

High accuracy and frequency local localization is the key technology of unmanned aerial vehicles (UAVs) in the confined areas and complicated conditions such as indoor flight, landing on ship deck and flight in GPS-denied environments and so on. In this paper, based on ultra-wideband (UWB) technique an observation-augmented EKF based local 3-D localization method is proposed for improving the accuracy when a moving target is tracked. In the first, a weighted least square (WLS) localization algorithm is proposed based on range measurements for improving the accuracy of 3-D localization. In the second, the position estimated by WLS is taken as partial measurements in an Extended Kalman Filter (EKF) to achieve the localization of a moving target so that the observation of the system is augmented and the accuracy is thus improved. Besides that, the ranging error model is analyzed with P440, a commercial UWB range sensor. Based on the result, the simulations are conducted to validate of the proposed method and the results show that the localization accuracy of the proposed method is greatly improved without remarkable computational complexity.