Towards collaborative multi-agent positioning based on combined Wi-Fi RTT/ UWB/ IMU measurements

<p>The recent advances in Information Technology (IT) and Micro-Electromechanical Systems (MEMS) technologies and their global adoption in contemporary smartphone and PDA devices enables the introduction of novel approaches for indoor positioning applications that combine multi-sensor capabilities.</p> <p>In this regard, Radio-frequency (RF), high accuracy ranging technologies operating in the Ultra-Wide Band (UWB) spectrum have recently been introduced in contemporary smartphone devices. Additionally, the adoption of Wi-Fi RTT technology in the most recent smartphone devices facilitates Peer-to-Infrastructure (P2I) medium level accuracy ranging in a widespread and seamless manner together with the standard web access functionality. Applications requiring absolute positioning of moderate to low accuracy may depend on Wi-Fi RTT-only systems, while high-accuracy UWB ranging would facilitate cases demanding safety-critical proximity reliant standards. Positioning architectures optimally utilizing these Two-Way Ranging (TWR) technologies may provide increased coverage and flexibility for indoor conditions in cases that a higher level of accuracy and availability is required.</p> <p>This study aims at utilizing RF-based range measurements and to combine them optimally into a Pedestrian to Infrastructure (P2I), as well as, Pedestrian to Pedestrian (P2P) collaborative functional model aided by inertial measurements for indoor positioning. The implementation of the proposed approach utilizes simulation-based TWR data from four infrastructure nodes to four roving nodes, whereas operational elements for each technology, such as sampling rate, data formatting and communications scheduling are taken into account.</p> <p>The distinct working scenarios examined in this study are as follows.&#160; Firstly, we examine separately the performance of the two technological approaches (i.e., Wi-Fi RTT and UWB) for P2I positioning scenarios.&#160; Secondly, we study the performance of the fuse the combined use of these technologies.&#160; For this purpose, we employ a scenario featuring a mixture of Wi-Fi RTT anchor and UWB static rover ranges. Finally, the potential (benefits and limitations) of the inclusion of IMU-based Azimuth information in the KF computation is evaluated for all scenarios. The results obtained from this investigation indicate a potential improvement in position accuracy of the order of 29% and 37% for Wi-Fi RTT/ UWB and Wi-Fi RTT/ UWB/ IMU solutions accordingly.</p>