Robotic manipulation of thin objects within off-the-shelf parallel grippers with a vibration finger

Common parallel grippers are limited to closing on an object without the ability for intrinsic in-hand manipulation. Nevertheless, parallel grippers are widely used due to their simplicity and low-cost while relying on extrinsic capabilities for manipulating the object. In this paper, a simple and low-cost mechanism is proposed for augmenting a parallel gripper with intrinsic in-hand manipulation abilities. A novel vibration-based finger was proposed where an off-the-shelf eccentric rotating mass motor along with a simple rotary actuator apply directional movement forces on a grasped thin object. The motion is based on the stick–slip phenomenon and exerted with no exposed moving parts. Along with the mechanism, a simple control law is proposed to manipulate the object to desired position goals and along paths. Furthermore, the ability to manipulate various objects is demonstrated. Experimental results show the ability to manipulate an object with accuracy of less than 2 mm. The experiments demonstrate the merits of the approach granting in-hand manipulation capabilities, that previously were not possible, to any parallel gripper.