Reasoning simplified volumetric shapes for robotic grasping

This paper presents a method for reasoning volumetric shapes for robotic grasping based on a data-driven approach. The global information about position, orientation and geometrical property of objects is necessary for successful execution of the target approach and the preparation, at the early stage of grasping, rather than fine details of the shapes. A pair of occluding contours is used to extract a simplified 3D shape of circular generalized cylinders (GCs) holding the information. Based on the GC model, which is represented by a family of spheres of varying radii with their centers on its axis, the stereo matching between the contour pair is implemented using the geometrical invariance of spheres. The shapes of blobs and sticks can be simplified as spheres and the families of spheres, respectively. Compared with the range-data based method, its computation is inexpensive, directive and has unique solution. The case of multiple and overlap objects is also addressed.