Vision-based 3-D grasping of 3-D objects with a simple 2-D gripper

Object grasping or localization is an essential stage in automatic manufacturing processes. In general, stable grasping of 3-D objects is achieved by a multifinger hand. Different from the existing approaches, in this paper, we propose a novel vision-based method for grasping 3-D objects with a simple 2-D gripper. We describe the grasping strategy, the range of 3-D objects which can be grasped, and the region of grasping orientations which can guarantee successful actions. The proposed method facilitates the freedom of grasping orientation, which endows the strategy with a larger application range. Furthermore, we also explain the potential applications of the proposed method in grasping 3-D objects with other 2-D grippers. Although the proposed method uses a 2-D gripper and 2-D vision information, it can be regarded as a 3-D grasping approach due to the following facts. 1) The objects to be grasped are 3-D. The grasping process and the grasping orientations are analyzed and given in a 3-D space. 2) The contact points between the object and the gripper are not always in a 2-D plane. In the proposed method, the concept attractive region in configuration space, which was proposed in the previous work, is introduced to analyze the whole grasping process. Compared with other traditional methods, the proposed method directly gives the range of objects which can be grasped as well as the region of grasping orientations. By establishing the relationship between our method and traditional ones, it is proved that the bottom of the attractive region corresponds to a stable grasp.