Hoecken-D Hand: A Novel Robotic Hand for Linear Parallel Pinching and Self-Adaptive Grasping

2025-10-15

AI Summary

To address the challenge of manipulating objects of diverse shapes in unstructured environments, this paper proposes a single-actuated underactuated robotic hand. The design integrates an enhanced Hoecken linkage, a differential spring mechanism, and a dual parallelogram transmission structure to enable contact-triggered, automatic switching between linear parallel grasping and adaptive enveloping grasping. Kinematic modeling, force analysis, and parametric simulation-based optimization ensure fingertip parallelism and morphological adaptability throughout the entire motion range using only one linear actuator. A prototype fabricated via PLA 3D printing—featuring a grasp stroke of approximately 200 mm—demonstrates stable grasping of spherical, prismatic, and irregular objects under both modes. Experimental results validate the hand’s robustness and versatility across heterogeneous object geometries. This work significantly enhances functional integration and environmental adaptability of underactuated hands, offering a compact, cost-effective solution for dexterous manipulation in unstructured settings.

Technology Category

• Intelligent Robots: Manipulation
• Humans and AI: Interaction Techniques and Devices
• Search and Optimization: Sampling/Simulation-based Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

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.

Problem

• Achieving linear parallel pinching and adaptive grasping with one mechanism
• Enabling contact-triggered reconfiguration without additional actuators
• Providing compact cost-effective manipulation for unstructured environments

Innovation

• Modified Hoecken linkage enables linear parallel pinching
• Differential spring mechanism allows self-adaptive grasping transition
• Single linear actuator minimizes complexity and cost