This paper presents the Hoecken-D Hand, an underactuated robotic gripper that combines a modified Hoecken linkage with a differential spring mechanism to achieve both linear parallel pinching and a mid-stroke transition to adaptive envelope. The original Hoecken linkage is reconfigured by replacing one member with differential links, preserving straight-line guidance while enabling contact-triggered reconfiguration without additional actuators. A double-parallelogram arrangement maintains fingertip parallelism during conventional pinching, whereas the differential mechanism allows one finger to wrap inward upon encountering an obstacle, improving stability on irregular or thin objects. The mechanism can be driven by a single linear actuator, minimizing complexity and cost; in our prototype, each finger is driven by its own linear actuator for simplicity. We perform kinematic modeling and force analysis to characterize grasp performance, including simulated grasping forces and spring-opening behavior under varying geometric parameters. The design was prototyped using PLA-based 3D printing, achieving a linear pinching span of approximately 200 mm. Preliminary tests demonstrate reliable grasping in both modes across a wide range of object geometries, highlighting the Hoecken-D Hand as a compact, adaptable, and cost-effective solution for manipulation in unstructured environments.

翻译：本文提出 Hoecken-D 手，这是一种欠驱动机器人夹持器，通过将改进的 Hoecken 连杆机构与差动弹簧机构相结合，实现了线性平行捏取以及在中行程向自适应包络抓取的过渡。原 Hoecken 连杆机构经过重构，其中一个构件被替换为差动连杆，在保持直线导向的同时，实现了无需额外驱动器的接触触发重构。双平行四边形结构在常规捏取过程中保持指尖平行，而差动机构则允许一个手指在遇到障碍物时向内弯曲，从而提高了在不规则或薄壁物体上的抓取稳定性。该机构可由单个线性驱动器驱动，最大限度地降低了复杂性和成本；在我们的原型中，为简化设计，每个手指由各自的线性驱动器驱动。我们进行了运动学建模与力学分析，以表征抓取性能，包括在不同几何参数下的模拟抓取力与弹簧张开行为。该设计采用基于 PLA 的 3D 打印技术制作原型，实现了约 200 mm 的线性捏取跨度。初步测试表明，该手能在两种模式下可靠抓取多种几何形状的物体，凸显了 Hoecken-D 手作为一种紧凑、适应性强且经济高效的解决方案，适用于非结构化环境中的操作任务。