An effort for determining the actuating forces in a multi-finger tendon-driven robotic hand for grasping different objects

Multi-finger robotic hands are designed to perform secure and stable grasping of different objects similar to human hands. It is always desirable to evaluate the grasp capabilities of any robotic hand to check its performance. This paper discusses the grasp capability analysis of the four-finger tendon-actuated robotic hand. For this purpose, the mathematical model for cylindrical shaped objects is developed. These mathematical equations help in calculating the contact forces of every phalange of the finger on the surface of the grasped object. In this process tendon tensions and contact forces are determined theoretically for the finger and thumb separately while grasping objects of different sizes, weights, and materials from the derived equations. Lastly, the obtained results are experimentally validated by carrying out the grasp analysis of cylindrical objects of varying diameters and materials by the four-finger tendon-actuated robotic hand. Tendon tensions obtained experimentally are compared with those calculated from the derived equations and various conclusions are drawn based on the obtained results.