Development of Adaptive Gripper Enhancing Power Grasp Range and Linearity

This paper presents a gripper structure that improves the known potential limitations of curved fingertip movements and the restricted range of objects that can be grasped during power grasp in two-finger adaptive grippers. In the proposed gripper, a Grasshopper mechanism is applied to improve the movement of the fingertips, making it closer to a straight line. Additionally, a grasping method is implemented that allows the fingertips to move towards the palm of the gripper after grasping an object, thereby expanding the size range of objects that can be adaptively grasped. This movement of the fingertips also results in an increase in gripping force. The performance theoretically confirmed through kinematics and force analysis is verified through the development of a prototype. This prototype is used to validate the basic functions of the adaptive gripper and to assess improvements in the fingertip trajectory, demonstrating movement closer to a straight line. Additionally, the improvements in the size range of objects that can be adaptively grasped are verified. The proposed power grasp range ratio shows that the gripper can grasp objects up to 76.7% of the stroke, demonstrating an improved range compared to other two-finger adaptive grippers. Furthermore, the grasping motion of the proposed gripper demonstrates an increase in gripping force in the experiments.