Method to determine the orientation of a target vehicle

Abstract

A method to determine the heading or orientation of a target vehicle by a host vehicle, said host vehicle equipped with a lidar or radar system, said system including a sensor unit adapted to receive signals emitted from said host vehicle and reflected by said target vehicle, comprising: a) determining at least one reference angle being an initial estimate of target heading or orientation (β); b) emitting a signal from said system and determining a plurality of point radar or lidar detections belonging to said a target vehicle, said point detections having co-ordinates in the horizontal plane; c) formulating an initial rectangular boundary box from said point detections, where the bounding box is formulated such that such that two edges of the boundary box are drawn parallel to the reference angle and two sides are perpendicular to the reference angle and such that all the detections are either on the bounding box sides or lay within the bounding box and each edge has at least one detection point on it; d) for each point on lying on an edge of the boundary box, rotating a line coincident with the respective edge clockwise and anticlockwise until said line intersects another point detection or until a maximum angle of rotation is performed; and each time when said line intersects said another point detection, determining a correction angle Δi, where the correction angle is such that applied to the reference angle it gives an orientation candidate angle γi; e) in respect of each orientation candidate angle γi/correction angle Δi, determining a cost function; and f) selecting that orientation candidate angle having the lowest cost function.