Range finding and feature extraction by segmentation of images for mobile robot navigation

Abstract

This paper describes techniques to identify various features in a scene using a laser range finding sensor, scanning horizontally in one dimension. The authors describe the optical and electronic properties of the sensor, together with the distributed processing hardware. The authors present a method to recognise and parameterise straight lines and ellipses occurring together in ID range images. In particular, the authors: (1) Present a line fitting system which recursively fits points to line segments, given range and bearing information, and correctly accounts for the sensors error sources. This system also passes on unfitted points to the ellipse fitter. (2) Extend Rothwell and Zisserman's improvements to the Bookstein algorithm to determine ellipse parameters from few observed points which lie over a small angular excursion of the ellipse, for example a pipe in an industrial environment. (3) Discuss the problems of outliers, and develop methods of recognising and rejecting them, including the use of intensity as well as range data. The authors show solutions to these problems on real data, and finally discuss further methods they might use to improve the ellipse fitting.