The Indoor Positioning and Indoor Navigation (IPIN) conference holds an annual competition in which indoor localization systems from different research groups worldwide are evaluated empirically. The objective of this competition is to establish a systematic evaluation methodology with rigorous metrics both for real-time (on-site) and post-processing (off-site) situations, in a realistic environment unfamiliar to the prototype developers. For the IPIN 2018 conference, this competition was held on September 22nd, 2018, in Atlantis, a large shopping mall in Nantes (France). Four competition tracks (two on-site and two off-site) were designed. They consisted of several 1 km routes traversing several floors of the mall. Along these paths, 180 points were topographically surveyed with a 10 cm accuracy, to serve as ground truth landmarks, combining theodolite measurements, differential global navigation satellite system (GNSS) and 3D scanner systems. 34 teams effectively competed. The accuracy score corresponds to the third quartile (75 th percentile) of an error metric that combines the horizontal positioning error and the floor detection. The best results for the on-site tracks showed an accuracy score of 11.70 m (Track 1) and 5.50 m (Track 2), while the best results for the off-site tracks showed an accuracy score of 0.90 m (Track 3) and 1.30 m (Track 4). These results showed that it is possible to obtain high accuracy indoor positioning solutions in large, realistic environments using wearable light-weight sensors without deploying any beacon. This paper describes the organization work of the tracks, analyzes the methodology used to quantify the results, reviews the lessons learned from the competition and discusses its future.
ABSTRACT. We introduce a novel probabilistic algorithm (CPRM) for real-time motion planning in the configuration space C. Our algorithm differs from a Probabilistic Road Map algorithm (PRM) in the motion between a pair of anchoring points (local planner) which takes place on the boundary of the obstacle subspace O. We define a varying potential field f on ∂O as a Morse function and follow ∇f . We then exemplify our algorithm on a redundant worm climbing robot with n degrees of freedom and compare our algorithm running results with those of PRM.
A continuous measure of symmetry and the Voronoi entropy of 2D patterns representing Voronoi diagrams emerging from the Penrose tiling were calculated. A given Penrose tiling gives rise to a diversity of the Voronoi diagrams when the centers, vertices, and the centers of the edges of the Penrose rhombs are taken as the seed points (or nuclei). Voronoi diagrams keep the initial symmetry group of the Penrose tiling. We demonstrate that the continuous symmetry measure and the Voronoi entropy of the studied sets of points, generated by the Penrose tiling, do not necessarily correlate. Voronoi diagrams emerging from the centers of the edges of the Penrose rhombs, considered nuclei, deny the hypothesis that the continuous measure of symmetry and the Voronoi entropy are always correlated. The Voronoi entropy of this kind of tiling built of asymmetric convex quadrangles equals zero, whereas the continuous measure of symmetry of this pattern is high. Voronoi diagrams generate new types of Penrose tiling, which are different from the classical Penrose tessellation.
In spatial designs of wire-driven parallel robots, collisions between wires by limiting platform trajectories. The common practice for avoiding collisions between wires is by limiting the moving platform trajectories. However, as opposed to rigid links, wires may tangle and the robot may still be functional. Hence, the purpose of this work is to examine the possibility of permitting wire collisions and thus expanding the workspace of the robot. Under the assumptions of negligible wire mass and diameter and negligible friction between the wires, the inverse kinematics of a robot with two colliding wires is formulated and was solved numerically. In addition, linearization was performed and found to be accurate excluding the initial steps of collision. To resolve this, approximated systems were solved analytically (up to univariate high-order polynomials) using an elimination method that provides accurate results. An experimental setup with two motorized wires was built and the theoretical and experimental results are presented. Velocities and forces mappings for the wire-driven parallel robot under wire collisions were also formulated. It should be noted that unlike the collisions-free case, these two mappings are not identical.
The paper reports studies on the motion planning problem for planar star-shaped manipulators. These manipulators are formed by joining k "legs" to a common point (like the thorax of an insect) and then fixing the "feet" to the ground. The result is a planar parallel manipulator with k 1 1 independent closed loops. A topological analysis is used to understand the global structure of the configuration space so that the planning problem can be solved exactly. The worst-case complexity of the algorithm is O1k 3 N 3 2, where N is the maximum number of links in a leg. Examples illustrating the method are given.
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