16 research outputs found
Visual-UWB Navigation System for Unknown Environments
Navigation applications relying on the Global Navigation Satellite System
(GNSS) are limited in indoor environments and GNSS-denied outdoor terrains such
as dense urban or forests. In this paper, we present a novel accurate, robust
and low-cost GNSS-independent navigation system, which is composed of a
monocular camera and Ultra-wideband (UWB) transceivers. Visual techniques have
gained excellent results when computing the incremental motion of the sensor,
and UWB methods have proved to provide promising localization accuracy due to
the high time resolution of the UWB ranging signals. However, the monocular
visual techniques with scale ambiguity are not suitable for applications
requiring metric results, and UWB methods assume that the positions of the UWB
transceiver anchor are pre-calibrated and known, thus precluding their
application in unknown and challenging environments. To this end, we advocate
leveraging the monocular camera and UWB to create a map of visual features and
UWB anchors. We propose a visual-UWB Simultaneous Localization and Mapping
(SLAM) algorithm which tightly combines visual and UWB measurements to form a
joint non-linear optimization problem on Lie-Manifold. The 6 Degrees of Freedom
(DoF) state of the vehicles and the map are estimated by minimizing the UWB
ranging errors and landmark reprojection errors. Our navigation system starts
with an exploratory task which performs the real-time visual-UWB SLAM to obtain
the global map, then the navigation task by reusing this global map. The tasks
can be performed by different vehicles in terms of equipped sensors and payload
capability in a heterogeneous team. We validate our system on the public
datasets, achieving typical centimeter accuracy and 0.1% scale error.Comment: Proceedings of the 31st International Technical Meeting of the
Satellite Division of The Institute of Navigation (ION GNSS+ 2018
WUB-IP : a high-precision UWB positioning scheme for indoor multi-user applications
High-precision positioning scheme, an important part of the indoor navigation system, can be implemented using an ultra-wide band (UWB) based ranging system. Recently, solutions for precise positioning in dense multi-path and non-line-of-sight (NLOS) conditions have attracted a lot of attention in literature. On the other hand, it is expected that Waveform Division Multiple Access (WDMA) technology for multi-user UWB positioning application will be indispensable in the near future. In this regard, a WDMA-UWB based positioning scheme is investigated in this paper, for enhancing the performance of positioning accuracy in multi-user applications. In accordance with practical requirements of indoor positioning, we propose a new indoor positioning scheme, termed as WUB-IP. This scheme adopts WDMA for multiple access, and utilizes an entropy-based approach for the Time of Arrival (TOA) estimation. Moreover, a transfer learning approach is used for ranging error mitigation in NLOS conditions, in order to improve the positioning accuracy in NLOS conditions. System-level simulations demonstrate that the proposed scheme enhances the performance of indoor positioning for multi-user applications