This paper presents a single-actuator passive gripper that achieves both stable grasping and continuous bidirectional in-hand rotation through mechanically encoded power transmission logic. Unlike conventional multifunctional grippers that require multiple actuators, sensors, or control-based switching, the proposed gripper transitions between grasping and rotation solely according to the magnitude of the applied input torque. The key enabler of this behavior is a Twisted Underactuated Mechanism (TUM), which generates non-coplanar motions, namely axial contraction and rotation, from a single rotational input while producing identical contraction regardless of rotation direction. A friction generator mechanically defines torque thresholds that govern passive mode switching, enabling stable grasp establishment before autonomously transitioning to in-hand rotation without sensing or active control. Analytical models describing the kinematics, elastic force generation, and torque transmission of the TUM are derived and experimentally validated. The fabricated gripper is evaluated through quantitative experiments on grasp success, friction-based grasp force regulation, and bidirectional rotation performance. System-level demonstrations, including bolt manipulation, object reorientation, and manipulator-integrated tasks driven solely by wrist torque, confirm reliable grasp to rotate transitions in both rotational directions. These results demonstrate that non-coplanar multifunctional manipulation can be realized through mechanical design alone, establishing mechanically encoded power transmission logic as a robust alternative to actuator and control intensive gripper architectures.

翻译：本文提出一种单驱动器被动夹持器，通过机械编码的动力传递逻辑，实现了稳定抓取与连续双向手内旋转的双重功能。与传统需要多个驱动器、传感器或基于控制切换的多功能夹持器不同，所提出的夹持器仅根据施加输入扭矩的大小，在抓取与旋转模式间自主切换。实现该行为的关键在于扭曲欠驱动机构，该机构能从单一旋转输入产生非共面运动（即轴向收缩与旋转），且在任意旋转方向下均产生相同的收缩量。摩擦发生器通过机械方式定义了控制被动模式切换的扭矩阈值，使得夹持器能在无传感或主动控制的情况下，先建立稳定抓持，随后自主过渡至手内旋转模式。本文推导了描述TUM运动学、弹性力生成及扭矩传递的解析模型，并通过实验验证。通过对抓取成功率、基于摩擦的抓取力调节及双向旋转性能的定量实验，对制备的夹持器进行了评估。系统级演示（包括螺栓操作、物体重定向以及仅通过腕部扭矩驱动的机械臂集成任务）证实了夹持器在双向旋转中均能实现从抓取到旋转的可靠切换。这些结果表明，非共面多功能操作可仅通过机械设计实现，从而确立了机械编码动力传递逻辑作为驱动器密集与控制密集型夹持器架构的可靠替代方案。