Über den Einsatz einer LASER-Entfernungsbildkamera an autonomen Fahrzeugen

Abstract

This thesis describes development and structure of an autonomous mobile robot, equipped with a Range-Image-Camera. The Range-Image-Camera (RIC or german: EBK) is a new measuring-system wich uses the time of flight and intensity of short laserflashes to get high-definition greyscale- and rangeimages of its actual environment. A rangeimage is more or less the same like a greyscale-image, but instead of brightness it contains an object range in every pixel of the CCD-array. This paper will explain the necessary physics, resolutions, conditions of environment and algorithms for rangeimage processing.Then a concept is shown, how to use threedimensional rangeimages of the workspace to provide navigation and obstacle avoidance for an autonomous wheelchair. Therefore a vector-based mathe-matical environment and vehicle model is used. This model transforms areas of the same spatial size to planes parallel to the floor, defined by its lower and upper boundaries in z-direction.The routeplanning algorithms are based on a global, multilevel environmental map. If the wheelchair detects new obstacles while driving, they are added to the global map. This means, the robot can be used in known and unknown environments. The software of navigation has the ability to explore the world in the area, which is necessary to reach a given destination.In environments with many obstacles the multilevel-model allows to solve complex navigation-problems, like turnings of 180 degrees with the seat passing under a table or going through narrow doors. This is shown in some examples at the end of this thesis.