“Mobile Robot Localization based on Ultra-Wide-Band Ranging: A Particle Filter Approach”, Robotics and Autonomous Systems (2009)
Abstract: This article addresses the problem of mobile robot localization using Ultra-Wide-Band (UWB) range measurements. UWB is a radio technology widely used for communications that recently is receiving increasing attention also for positioning applications. In these cases, the position of a mobile transceiver is determined from the distances to a set of fixed, well-localized beacons. Though this is a well-known problem in the scientific literature (the trilateration problem), the peculiarities of UWB range measurements (basically, distance errors and multipath effects) demand a different treatment to other similar solutions as for example those based on laser. This work presents a thorough experimental characterization of UWB ranges within a variety of environments and situations. From these experiments we derive a probabilistic model which is then employed by a particle filter to combine different readings from real UWB beacons as well as the vehicle odometry. To account for the possible offset error due to multipath effects, the state tracked by the particle filter includes the offset of each beacon in addition to the planar robot pose (x,y,φ), both estimated sequentially. We show real experimental results for a robot moving in indoor scenarios covered by three UWB beacons that validate our proposal .
2. Source code
The program employed in the experiments is ro-localization, a special case of particle-filter localization with the extended state which copes with dynamic biases of the beacon ranges and a special real-time visualization in 3D. This program is available for download within the MRPT packages (starting at version 0.6.2). Source code of the application can be found in the directory MRPT/apps/ro-localization/.
This video represents how our augmented-state particle filter is able to cope with the abrupt changes in the offsets of UWB ranges given by the radio sensors. The video is also available on YouTube: