Representation and recovery of road geometry in YARF

YARF, like several other road following systems, models the road as features which form concentric circular arcs lying in a flat ground plane. Two approximations are made in order to use a linear estimation technique to determine the spine parameters. The paper demonstrates that errors due to these approximations are reduced substantially by estimating the spine parameters in a data-dependent coordinate system rather than in a vehicle-centered coordinate system. It discusses the problem of estimating the spine parameters in the presence of outlying data. Using standard least squares estimation can result in the vehicle drifting off the road due to errors in the parameter estimates caused by such contaminants in the data. The use of least median squares estimation to overcome these problems is discussed