Underactuated grasp acquisition and stability using friction based coupling mechanisms

Underactuated fingers have been extensively studied and optimized in order to achieve better grasp performance in terms of object acquisition and stability. However, little work has been done related to the coupling mechanisms between the fingers and their effects on grasp performance. This paper presents a novel method of underactuated finger coupling that utilizes friction and allows for increased stability and adaptability of robotic grippers. We show that variable friction within the coupling element can help the system maintain kinematic form closure while not affecting non-closure forces during grasp acquisition. A proof of concept prototype demonstrates the increased stability of objects within the grasp as compared to traditional coupling mechanisms.