Design Principle of a Dual-Actuated Robotic Hand With Anthropomorphic Self-Adaptive Grasping and Dexterous Manipulation Abilities

How to use few actuators to endow a multifingered robotic hand with the human grasping and manipulation abilities is a challenging problem. This article develops a design principle of a five-fingered robotic hand with only two actuators, which guarantees the designed hand can replicate a large portion of the grasping and a limited portion of the manipulation abilities of the human hand: simultaneously move all joints before contacting objects like the natural reach-to-grasp process of the human hand; self-adaptively pinch/envelop objects with arbitrary shapes; and carry out dexterous manipulation, such as in-hand manipulation of a ball and screwing bottle cap. The core design ideas involve two levels. The higher level idea is to construct a robotic design theory ensuring thumb and fingers driven independently and four fingers driven synergistically so that the opposable thumb with manual abduction/adduction function can move coordinately with four fingers to ensure abundant anthropomorphic grasps and in-hand manipulations. The lower level idea is to establish a mechanism design method that embeds human two primary eigengrasps into a novel single-actuated differential palm mechanism consisting of gears, drag axes, and slider elements, so that the mechanism can always replicate the grasping behaviors of human hand, no matter how the differential processes it would perform during grasping. Finally, we design a mini X-hand to verify our proposed design principle and reproduce 29 types out of 33 grasping types and some manipulations that are commonly used by human hands in daily life.