Tendon-Driven Reciprocating and Non-Reciprocating Motion via Snapping Metabeams

2026-02-20

AI Summary

This work addresses the challenge of efficiently achieving controllable reciprocating and non-reciprocating motions in soft robotics by introducing a geometry-driven paradigm based on helical metamaterial beams. By leveraging tendon actuation to trigger nonlinear snap-through instability, the design enables tunable critical buckling loads and stability solely through boundary constraint modulation, achieving large, reversible deformations even in rigid PLA material. Integrating fused deposition modeling (FDM) 3D printing, nonlinear mechanical analysis, and tailored boundary conditions, the approach is successfully implemented in a swimming robot that attains a propulsion speed of 81 mm/s (approximately 0.4 body lengths per second) in non-reciprocating mode, demonstrating its high efficiency and programmable actuation capabilities.

Technology Category

• Intelligent Robots: Motion and Path Planning
• Search and Optimization: Sampling/Simulation-based Search
• Machine Learning: Bio-inspired Learning

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments

Abstract

Snapping beams enable rapid geometric transitions through nonlinear instability, offering an efficient means of generating motion in soft robotic systems. In this study, a tendon-driven mechanism consisting of spiral-based metabeams was developed to exploit this principle for producing both reciprocating and non-reciprocating motion. The snapping structures were fabricated using fused deposition modeling with polylactic acid (PLA) and experimentally tested under different boundary conditions to analyze their nonlinear behavior. The results show that the mechanical characteristics, including critical forces and stability, can be tuned solely by adjusting the boundary constraints. The spiral geometry allows large reversible deformation even when made from a relatively stiff material such as PLA, providing a straightforward design concept for controllable snapping behavior. The developed mechanism was further integrated into a swimming robot, where tendon-driven fins exhibited two distinct actuation modes: reciprocating and non-reciprocating motion. The latter enabled efficient propulsion, producing a forward displacement of about 32 mm per 0.4 s cycle ($\approx$ 81 mm/s, equivalent to 0.4 body lengths per second). This study highlights the potential of geometry-driven snapping structures for efficient and programmable actuation in soft robotic systems.

Problem

• tendon-driven
• snapping metabeams
• nonlinear instability
• soft robotics
• reciprocating motion

Innovation

• snapping metabeams
• tendon-driven actuation
• nonlinear instability
• programmable motion
• soft robotics