PuffyBot: An Untethered Shape Morphing Robot for Multi-environment Locomotion

2025-11-13

AI Summary

Addressing the challenge of amphibious cross-domain autonomous locomotion, this paper introduces PuffyBot—a bioinspired deformable robot modeled after amphibians. Methodologically, it integrates a scissor-type telescoping mechanism with a pendulum-linkage system to enable dynamic body-volume modulation (255.00–423.75 cm³) and 90° reorientation of all four limbs, facilitating seamless transitions among terrestrial crawling, surface swimming, and subaquatic diving. Crucially, buoyancy control is achieved passively via morphological changes that actively regulate displaced water volume, eliminating the need for dedicated buoyancy actuators. The robot employs coordinated linear actuators and servo motors for actuation, is encapsulated in TPU waterproof fabric, and operates untethered for two hours on a 1000 mAh battery. Experimental validation confirms stable locomotion across heterogeneous environments and demonstrates its capacity to counteract a 3.237 N downward force.

Technology Category

• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Humans and AI: Interaction Techniques and Devices
• Computer Vision: Vision for Robotics & Autonomous Driving

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: Multilingual and cross-lingual Web search

Abstract

Amphibians adapt their morphologies and motions to accommodate movement in both terrestrial and aquatic environments. Inspired by these biological features, we present PuffyBot, an untethered shape morphing robot capable of changing its body morphology to navigate multiple environments. Our robot design leverages a scissor-lift mechanism driven by a linear actuator as its primary structure to achieve shape morphing. The transformation enables a volume change from 255.00 cm3 to 423.75 cm3, modulating the buoyant force to counteract a downward force of 3.237 N due to 330 g mass of the robot. A bell-crank linkage is integrated with the scissor-lift mechanism, which adjusts the servo-actuated limbs by 90 degrees, allowing a seamless transition between crawling and swimming modes. The robot is fully waterproof, using thermoplastic polyurethane (TPU) fabric to ensure functionality in aquatic environments. The robot can operate untethered for two hours with an onboard battery of 1000 mA h. Our experimental results demonstrate multi-environment locomotion, including crawling on the land, crawling on the underwater floor, swimming on the water surface, and bimodal buoyancy adjustment to submerge underwater or resurface. These findings show the potential of shape morphing to create versatile and energy efficient robotic platforms suitable for diverse environments.

Problem

• Develops a shape-morphing robot for land and water locomotion
• Achieves buoyancy control through volume change for aquatic mobility
• Enables seamless transition between crawling and swimming modes

Innovation

• Scissor-lift mechanism enables robot shape morphing
• Bell-crank linkage adjusts limbs for locomotion transition
• Waterproof TPU fabric ensures aquatic environment functionality