PASA finger: A novel parallel and self-adaptive underactuated finger with pinching and enveloping grasp

The traditional dexterous robot hand has always many grasping modes but it is difficult to control due to a lot of actuators and grasping tasks for different objects. A self-adaptive underactuated robot hand uses few motors to drive several joints, but is lack of the ability to pinch objects. In order to combine the abilities of dexterous hand and self-adaptive hand, this paper presents a novel design of a parallel and self-adaptive underactuated robot finger with pinching and enveloping grasp, called PASA finger. Due to its special structure, it can realize the pinching grasp or enveloping grasp, according to the different positions, shapes and sizes of the target object, which is a self-adaptive process. Analysis results show that an application force on the distal phalange keeps the parallel mechanism unchanged, while an application force on the proximal phalange destroys the parallel mechanism and leads the distal phalange move towards the target object, which is another self-adaptive process. The PASA hand is suitable for both industry and home application.