Composite AOA: A Practical Approach for Relative Localization of Companion UGV

The companion UGV is primarily designed to provide logistics support for light forces. We present an accurate and reliable wireless localization method for companion UGV, named composite AOA. The method can eliminate the distorted ranging measurements under the inborn NLOS scene, by selecting anchor combinations adaptively. The localization system is composed of 4 UWB anchor modules mounted on four corners of a companion UGV, and a UWB tag module held by a person. Firstly, Kalman filter is implemented on the real-time ranging between UWB modules, so as to provide more reliable ranging measurements. Secondly, we positioned the tag module based on all anchors and obtained its initial angle relative to the UGV. Then we divided the two-dimensional local zone around the UGV into 8 sections, separated as 2 types: perpendicular sections and transition sections. The perpendicular sections are sectors in the front, back, left and right side of a UGV, while the transition sections are 4 corner sectors of a UGV. As for the tag in perpendicular sections, the AOA positioning method was implemented based on the ranging to 2 adjacent anchors only. As for the tag in transition sections, the ranging measurements of 2 adjacent groups of “anchors pairs” were selected for AOA positioning separately, and then the results were averaged to ensure stability and smoothness. At last, we present 2 experiments to prove that our composite AOA algorithm is more advanced than state-of-the-art commercial algorithm for the relative localization of companion UGV.