Force-Sensitive Underactuated Three-Finger Robot Hand

<jats:title>Abstract</jats:title> <jats:p>This article presents the design, prototyping, and evaluation of a novel underactuated, three-fingered robotic hand engineered to simultaneously satisfy the requirements of high-power adaptive grasping and delicate material handling. Driven by four DC motors across a total of 10 degrees-of-freedom, the mechatronic system features a compact underactuated layout with a reconfigurable thumb. By incorporating an additional rotational degree-of-freedom at the thumb base, the hand enables multiple opposition configurations and diverse grasp topologies, including precision, power, and key-type grasps. Each finger integrates a custom-designed fingertip force-sensing unit embedded into a compliant fingertip structure, providing the underlying hardware necessary for future advanced dexterous manipulation. To eliminate the industry-wide bottleneck of wire routing accumulation and progressive mechanical fatigue across moving linkages, a novel slip-ring-based communication architecture is introduced. This framework enables cable-less signal transmission through rotating finger joints, utilizing localized sensory digitization directly on the phalanges, allowing custom slip-ring units embedded within the rotating joints to pass a minimal six-wire interface. Finally, this work details a formal kinematic and static analysis of the proposed finger transmission mechanism, presenting loop-closure equations, Jacobian derivation, transmission analysis, contact force modeling, and spring force analysis. Experimental grasping validations demonstrate the hand’s structural adaptability and payload variation.</jats:p>