Image moments: generic descriptors for decoupled image-based visual servo

Moments are generic and (usually) intuitive descriptors that can be computed from several kinds of objects defined either from closed contours (continuous object) or a set of points (discrete object). In this paper, we propose to use moments to design a decoupled image-based visual servo. The analytical form of the interaction matrix related to the moments computed for a discrete object is derived, and we show that it is different of the form obtained for a continuous object. Six visual features are selected to design a decoupled control scheme when the object is parallel to the image plane. This nice property is then generalized to the case where the desired object position is not parallel to the image plane. Finally, experimental results are presented to illustrate the validity of our approach and its robustness with respect to modeling errors.