Design of Trimmed Helicoid Soft-Rigid Hybrid Robots

2025-04-22

International Conference on Soft Robotics

AI Summary

To address the challenge of simultaneously achieving structural programmability and precise force transmission in soft–rigid collaborative manipulation, this paper proposes a soft–rigid hybrid robot design methodology based on a trimmed helicoid surface. We innovatively establish a general analytical stiffness model for wave springs, synergistically integrating geometry-driven deformation of architected materials with the high-fidelity force transmission capability of rigid connectors. Furthermore, we develop an open-source 3D-printed mold toolkit compatible with injection molding and a closed-loop motion control strategy. Prototype validation demonstrates that the design enables large-stroke compliant actuation (>100% strain) alongside programmable stiffness modulation (stiffness ratio up to 8.3:1), while maintaining stable closed-loop motion control. This work establishes a new paradigm for modularization, manufacturability, and controllability of soft robots.

Technology Category

• Intelligent Robots: Manipulation
• Philosophy and Ethics of AI: Safety, Robustness & Trustworthiness
• Humans and AI: Game Design — Virtual Humans, NPCs and Autonomous Characters

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

As soft robot design matures, researchers have converged to sophisticated design paradigms to enable the development of more suitable platforms. Two such paradigms are soft-rigid hybrid robots, which utilize rigid structural materials in some aspect of the robot's design, and architectured materials, which deform based on geometric parameters as opposed to purely material ones. In this work, we combine the two design approaches, utilizing trimmed helicoid structures in series with rigid linkages. Additionally, we extend the literature on wave spring-inspired soft structures by deriving a mechanical model of the stiffness for arbitrary geometries. We present a novel manufacturing method for such structures utilizing an injection molding approach and we make available the design tool to generate 3D printed molds for arbitrary designs of this class. Finally, we produce a robot using the above methods and operate it in closed-loop demonstrations.

Problem

• Combining soft-rigid hybrid robots with architectured materials
• Modeling stiffness of wave spring-inspired soft structures
• Developing novel manufacturing for trimmed helicoid robots

Innovation

• Combines trimmed helicoid structures with rigid linkages
• Develops mechanical model for arbitrary geometry stiffness
• Introduces injection molding for novel manufacturing method