Human Palm Performance Evaluation and the Palm Design of Humanoid Robotic Hands

Losing the ability to deform the palm is unthinkable for a human hand, and the same is true for a humanoid robotic hand. Here, we aim to evaluate the performance of human palms and develop a palm-movable humanoid robotic hand with a few actuators. We quantified the palm morphological characteristics by analyzing the palm morphological parameters collected from 42 subjects. Subsequently, we constructed a kinematic model of the human hand with these characteristics to quantitatively analyze how a movable palm influences the finger workspace. We found that a movable palm can significantly improve fingertip-reachable space (at least 50%) and increase the capability of fingers to oppose each other (at least 14%). Furthermore, we designed a palm-movable humanoid robotic hand with only four actuators and compared the grasping performance of this prototype with that of a palm-fixed robotic hand and a human hand. The results suggest that a movable palm contributes to enhancing anthropomorphism, adaptability, and grip stability in humanoid robotic hands. Hence, our findings contribute to the development of dexterous robotic hands.