Topological-metric indoor path planning

Abstract

W artykule przedstawiono eksperyment posługujący się metodą hybrydową: asocjacyjno-wizyjne podejście - adaptacja metody QualNav oraz pomiar odległości. Do praktycznej realizacji użyte robot Lego Mindstorms NXT 2.0, kamera telefonu komórkowego oraz sonar. Eksperymenty wykazały dużą skuteczność wykonanych poleceń. Scenariusz jest bardzo aktualny dla realizacji zadań autonomicznego poruszania się w dużych salach gdzie często pozycja i orientacja przedmiotów (krzesła, fotele, skrzynie itd.) nie jest stała.Quality strategies used in mobile robot navigation [4][6] can be successfully supplemented by quantity ones [2, 8]. In this paper we present a path-planning approach based on a hybrid [1][7], topological-metric strategy. It is based on topological navigation [5] adapted to enclosed spaces, expanded with sonar data-updating. The landmarks are assumed to possess properties common to those of office furniture, additionally marked with a color - a time-saving simplification (Fig. 1). Measurements of the distance have a secondary role: the distance was only measured if unambiguous identification of the registered objects was not obtained. What is significant in this approach is that parts of the landmarks have a non-steady position: instead by a fixed point, their presence is described by a zone (Fig. 2). The main task executed by a vehicle is to follow a route achieving the end position. The command structure (giving the route) is a data sequence - edges which have to be crossed over by the robot (Fig. 3). Besides odometry difficulties [3, 8], the great localization accuracy and the time impact of the scanning angle of a robot (Fig. 4) was experimentally proved. Dependencies between the precision of task-execution (accuracy of position achievement), work duration and the scan-angle used by the robot were examined and described. All final observations are presented in Tab.1. The scan-angle of about 25o was suggested based on investigations. The used scenario is very suitable for large office halls, where the position of the objects (chairs, armchairs, chests, etc.) is often not constant