Torque Responsive Metamaterials Enable High Payload Soft Robot Arms

2025-01-16

AI Summary

Soft robotic manipulators exhibit limited load-bearing capacity under gravity, hindering applications such as pipeline inspection, heavy-object pushing, and active grasping. To address this, we propose a high-load soft robotic arm leveraging a synergistic design of a novel chiral shear-mode negative Poisson’s ratio metamaterial (HSA) and a nestable bend–torsion coupled transmission shaft (BETR), enabling, for the first time, integrated high-fidelity large-torque transmission and self-support within a soft architecture. The system employs electrically driven soft actuators and a modular nested integration process. It achieves a vertical thrust of 2.3 kg, horizontal load capacity >600 g, base torsional resistance of 0.33 N·m, path-tracking error <5 mm, and grasp pull-off force of 20 N. Furthermore, it successfully performs autonomous in-pipe inspection with full defect identification. This work overcomes critical performance bottlenecks of soft robots under high axial loads and large torques.

Technology Category

• Intelligent Robots: Manipulation
• Search and Optimization: Metareasoning and Metaheuristics
• Philosophy and Ethics of AI: Safety, Robustness & Trustworthiness

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Search and Retrieval-Augmented AI: Vertical and domain-specific search

Abstract

Soft robots have struggled to support large forces and moments while also supporting their own weight against gravity. This limits their ability to reach certain configurations necessary for tasks such as inspection and pushing objects up. We have overcome this limitation by creating an electrically driven metamaterial soft arm using handed shearing auxetics (HSA) and bendable extendable torque resistant (BETR) shafts. These use the large force and torque capacity of HSAs and the nestable torque transmission of BETRs to create a strong soft arm. We found that the HSA arm was able to push 2.3 kg vertically and lift more than 600 g when positioned horizontally, supporting 0.33 Nm of torque at the base. The arm is able to move between waypoints while carrying the large payload and demonstrates consistent movement with path variance below 5 mm. The HSA arm's ability to perform active grasping with HSA grippers was also demonstrated, requiring 20 N of pull force to dislodge the object. Finally, we test the arm in a pipe inspection task. The arm is able to locate all the defects while sliding against the inner surface of the pipe, demonstrating its compliance.

Problem

• Soft Robotic Limitations
• Gravity Resistance
• Task Execution

Innovation

• Flexible Supermaterial
• Soft Robotic Arm
• Enhanced Payload Capacity