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A Novel Robot Hand with Hoeckens Linkages and Soft Phalanges for Scooping and Self-Adaptive Grasping in Environmental Constraints

Wentao Guo, Yizhou Wang, Wenzeng Zhang

TL;DR

The paper tackles robust, adaptive grasping in unstructured environments with a compact, underactuated hand. It proposes the Hockens-A Hand, which integrates the Hoeckens mechanism, a dual parallelogram, and a four-bar trigger, all driven by a single actuator, to realize three adaptive grasp modes: parallel pinching, asymmetric scooping, and enveloping. Through kinematic modeling and parametric optimization, it derives feasible four-bar dimensions and analyzes fingertip motion and grasping forces, followed by a 3D-printed prototype that experimentally validates the three modes on objects ranging from thin sheets to cans. The results demonstrate reliable performance under environmental constraints, highlighting a compact, cost-effective approach for versatile manipulation in real-world settings.

Abstract

This paper presents a novel underactuated adaptive robotic hand, Hockens-A Hand, which integrates the Hoeckens mechanism, a double-parallelogram linkage, and a specialized four-bar linkage to achieve three adaptive grasping modes: parallel pinching, asymmetric scooping, and enveloping grasping. Hockens-A Hand requires only a single linear actuator, leveraging passive mechanical intelligence to ensure adaptability and compliance in unstructured environments. Specifically, the vertical motion of the Hoeckens mechanism introduces compliance, the double-parallelogram linkage ensures line contact at the fingertip, and the four-bar amplification system enables natural transitions between different grasping modes. Additionally, the inclusion of a mesh-textured silicone phalanx further enhances the ability to envelop objects of various shapes and sizes. This study employs detailed kinematic analysis to optimize the push angle and design the linkage lengths for optimal performance. Simulations validated the design by analyzing the fingertip motion and ensuring smooth transitions between grasping modes. Furthermore, the grasping force was analyzed using power equations to enhance the understanding of the system's performance.Experimental validation using a 3D-printed prototype demonstrates the three grasping modes of the hand in various scenarios under environmental constraints, verifying its grasping stability and broad applicability.

A Novel Robot Hand with Hoeckens Linkages and Soft Phalanges for Scooping and Self-Adaptive Grasping in Environmental Constraints

TL;DR

The paper tackles robust, adaptive grasping in unstructured environments with a compact, underactuated hand. It proposes the Hockens-A Hand, which integrates the Hoeckens mechanism, a dual parallelogram, and a four-bar trigger, all driven by a single actuator, to realize three adaptive grasp modes: parallel pinching, asymmetric scooping, and enveloping. Through kinematic modeling and parametric optimization, it derives feasible four-bar dimensions and analyzes fingertip motion and grasping forces, followed by a 3D-printed prototype that experimentally validates the three modes on objects ranging from thin sheets to cans. The results demonstrate reliable performance under environmental constraints, highlighting a compact, cost-effective approach for versatile manipulation in real-world settings.

Abstract

This paper presents a novel underactuated adaptive robotic hand, Hockens-A Hand, which integrates the Hoeckens mechanism, a double-parallelogram linkage, and a specialized four-bar linkage to achieve three adaptive grasping modes: parallel pinching, asymmetric scooping, and enveloping grasping. Hockens-A Hand requires only a single linear actuator, leveraging passive mechanical intelligence to ensure adaptability and compliance in unstructured environments. Specifically, the vertical motion of the Hoeckens mechanism introduces compliance, the double-parallelogram linkage ensures line contact at the fingertip, and the four-bar amplification system enables natural transitions between different grasping modes. Additionally, the inclusion of a mesh-textured silicone phalanx further enhances the ability to envelop objects of various shapes and sizes. This study employs detailed kinematic analysis to optimize the push angle and design the linkage lengths for optimal performance. Simulations validated the design by analyzing the fingertip motion and ensuring smooth transitions between grasping modes. Furthermore, the grasping force was analyzed using power equations to enhance the understanding of the system's performance.Experimental validation using a 3D-printed prototype demonstrates the three grasping modes of the hand in various scenarios under environmental constraints, verifying its grasping stability and broad applicability.
Paper Structure (11 sections, 11 equations, 13 figures, 1 table)

This paper contains 11 sections, 11 equations, 13 figures, 1 table.

Table of Contents

  1. INTRODUCTION
  2. DESIGN
  3. Fingertip Translation: Design of Offset Hoeckens Linkage for Vertical Compliance
  4. Fingertip Orientation: Design of Parallelogram Linkage and Four-bar Linkage
  5. 3D Mechanism Embodiment: Compositional Modeling and Digital Prototype Realization
  6. ANALYSIS
  7. Kinematic Modeling and Parameter Optimization of Four-Bar Linkage
  8. Kinematic Analysis of Fingertip
  9. Grasping Force Analysis
  10. EXPERIMENTS
  11. CONCLUSIONS

Figures (13)

  • Figure 1: Hockens-A Hand.
  • Figure 2: Motion Analysis of the Hoeckens Linkage
  • Figure 3: Displacement characteristics of point D during linkage operation
  • Figure 4: Mechanism evolution: (a) Basic Hoeckens linkage, (b) Parallelogram-augmented design, (c) Four-bar integrated system, (d) Final composite mechanism.
  • Figure 5: Posture transition sequence from pinching to scooping.
  • ...and 8 more figures