Ultra-Wideband Aided UAV Positioning Using Incremental Smoothing with Ranges and Multilateration

In this paper, we present a novel smoothing approach for ultra-wideband (UWB) aided unmanned aerial vehicle (UAV) positioning. Existing works based on smoothing or filtering estimate 3D position of UAV by updating a solution for each single 1D low-dimensional UWB range measurement. However, a low-dimensional single range measurement merely acts as a weak constraint in a solution space for UAV position estimation, and thus it can often lead to incorrect estimation in unfavorable conditions. Inspired by the idea that the multilateration outcome can be utilized as a measurement providing a strong constraint, we utilize two types of UWB-based measurements: (i) each single 1D range as a high-rate measurement with a weak constraint, and (ii) multilateration outcome as a low-rate measurement with a strong constraint. We propose an incremental smoothing-based method that seamlessly integrates these two types of UWB-based measurements and inertial measurement into a unified factor graph framework. Through experiments under a variety of scenarios, we demonstrate the effectiveness of the proposed method.