Bias Compensated UWB Anchor Initialization using Information-Theoretic Supported Triangulation Points

Abstract

For Ultra-Wide-Band (UWB) based navigation, an accurate initialization of the anchors in a reference coordinate system is crucial for precise subsequent UWB-inertial based pose estimation. This paper presents a strategy based on information theory to initialize such UWB anchors using raw distance measurements from tag to anchor(s) and aerial vehicle poses. We include a linear distance-dependent bias term and an offset in our estimation process in order to achieve unprecedented accuracy in the 3D position estimates of the anchors (error reduction by a factor of about 3.5 compared to current approaches) without the need of prior knowledge. After an initial coarse position triangulation of the anchors using random vehicle positions, a bounding volume is created in the vicinity of the roughly estimated anchor position. In this volume, we calculate points which provide the maximal triangulation related information based on the Fisher Information Theory. Using these information theoretic optimal points, a fine triangulation is done including bias term estimation. We evaluate our approach in simulations with realistic sensor noise as well as with real world experiments. We also fly an aerial vehicle with UWB-inertial based closed loop control demonstrating that precise anchor initialization does improve navigation precision. Our initialization approach is compared to state-of-the-art as well as to an initialization without the simultaneous bias estimation.

Topics & Concepts