Vibration of Soft, Twisted Beams for Under-Actuated Quadrupedal Locomotion

2025-07-03

AI Summary

To address the limited locomotion modalities and poor environmental adaptability of underactuated, untethered centimeter-scale quadrupedal robots, this work proposes a novel vibration-driven locomotion paradigm enabled by compliant helical-beam legs. Leveraging only two actuators to excite structural resonance, the Flix-Walker achieves three distinct gait modes—walking, turning, and slope climbing—while relying on passive compliance to drastically simplify actuation and control. We establish an analytical dynamic model of the soft twisted-beam leg and derive a general criterion for selecting robust control parameters, ensuring stable locomotion across varying ground friction coefficients, surface inclinations, and external disturbances. Comprehensive simulation and experimental validation demonstrate reliable trajectory tracking and autonomous navigation in diverse unstructured environments, significantly enhancing motion robustness and terrain adaptability.

Technology Category

• Intelligent Robots: Motion and Path Planning
• Computer Vision: Low Level & Physics-based Vision
• Search and Optimization: Sampling/Simulation-based Search

Application Category

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

Abstract

Under-actuated compliant robotic systems offer a promising approach to mitigating actuation and control challenges by harnessing pre-designed, embodied dynamic behaviors. This paper presents Flix-Walker, a novel, untethered, centimeter-scale quadrupedal robot inspired by compliant under-actuated mechanisms. Flix-Walker employs flexible, helix-shaped beams as legs, which are actuated by vibrations from just two motors to achieve three distinct mobility modes. We analyze the actuation parameters required to generate various locomotion modes through both simulation and prototype experiments. The effects of system and environmental variations on locomotion performance are examined, and we propose a generic metric for selecting control parameters that produce robust and functional motions. Experiments validate the effectiveness and robustness of these actuation parameters within a closed-loop control framework, demonstrating reliable trajectory-tracking and self-navigation capabilities.

Problem

• Analyzing vibration-driven locomotion in soft, twisted beams
• Developing under-actuated quadrupedal robot with minimal motors
• Optimizing control parameters for robust mobility in varying environments

Innovation

• Helix-shaped beams as legs
• Two-motor vibration actuation
• Closed-loop control framework