The PG2 Gripper: an Underactuated Two-fingered Gripper for Planar Manipulation

The flexible grasping, twisting, and force sensing abilities of the gripper are theoretically significant and practically valuable to solve. However, it is still difficult for most existing grippers to realize these three functions simultaneously. In this paper, to realize the purposes of grasping, twisting, and sensing contact force, a novel parallel gripper the PG2 was developed. A two-finger grasping mechanism based on the parallelogram mechanism was designed and constructed. Meanwhile, to sense the contact force between the fingers and the object, a SEA-based force sensing mechanism was proposed. Then the relationship between the rotating angle of the object and the driver angle was calculated through kinematic analysis. Finally, a twisting platform was built and an evaluated experiment was carried out. The experimental results showed that the PG2 can grasp and twist the thin object with a high responding speed in the case of constant contact force. The novel mechanism for grasping, twisting, and sensing contact force has potential in the area that required high responding speed.