A New, Simple and Universal Four-Finger Gripper for 3D Objects Grasping

In manufacturing, it is common to handle objects with different geometries and weights. For example, there are more than ten types of objects required to assemble together in the automotive product line. The parallel-jaw gripper in wide use is inflexible and inefficient to meet the requirements. In this paper, a new, simple and flexible four-finger gripper, called CBF (Cross Bar Four-Finger) gripper, is designed to grasp various objects. The gripper with 8 degrees of freedom has compact architectures and can be easily built. It can perform both enveloping grasps and fingertip grasps. We present some properties of 3D objects that can be enveloping grasped. A Sufficient condition is given for selecting the stable fingertip grasping points. Two strategies are proposed to select the contact points in two grasp modes respectively. Some examples are presented to validate our approach.