Estimating the Position of a Sphere from Range Images

This paper describes two algorithms for accurately locating a spherical object in space using data collected from a scanning laser range finder. This work is designed to support the capture phase of a future rendezvous and sample return mission to Mars. The first algorithm finds the parameters of the sphere which optimally fit the set of data points. This method is shown to be quite slow, and unlikely to meet the accuracy requirements of the mission. The second algorithm makes a set of almostindependent estimates of the position of the center of the sphere, one from each scan line of data. These estimates are combined using regression to produce an aggregate estimate of the sphere position. This second algorithm is both fast enough, and accurate enough to meet mission requirements. TABLE OF CONTENTS