Polymander II: an amphibious salamander-inspired robot with contact and flow sensors

2026-05-23

AI Summary

This work addresses the challenge that existing amphibious robots struggle to simultaneously perceive terrestrial contact forces and underwater hydrodynamic forces, limiting their adaptability and locomotion robustness in complex environments. The authors propose a salamander-inspired amphibious robot featuring an innovative integration of compact Hall-effect sensors, enabling high-frequency synchronous detection of foot-end contact forces and lateral hydrodynamic forces (exteroception >500 Hz, proprioception at 100 Hz). Coupled with a dual-bus communication architecture and joint position–load sensing technology, the system supports multimodal sensor fusion and waterproof embedded operation. Experimental results demonstrate the robot’s efficient traversal across diverse amphibious terrains and highlight its potential to execute complex locomotion tasks through real-time sensory feedback.

Abstract

Robots benefit from sensory information to coordinate body movement, gain robustness against perturbations, and transit between different modes to adapt to various terrains. However, few amphibious robots can sense interactions with both terrestrial and aquatic environments. In this paper, we present a solution that uses Hall-effect sensors to sense foot contact forces and lateral hydrodynamic forces on a salamander-inspired amphibious robot. With two bus lines, the robot can simultaneously acquire this exteroceptive information at more than 500 Hz and proprioceptive information, such as joint positions and loads, at 100 Hz. The Hall-effect sensors used are compact, making them suitable for embedding in multiple positions within a robot, and exhibit high sensitivity to small forces. Moreover, because the sensor can be positioned separately from the measured object, waterproofing can be implemented with relative ease. Our tests demonstrate the robot's capabilities in traversing amphibious environments and its potential in using feedback control for more complex locomotion tasks.

Problem

• amphibious robot
• environmental interaction sensing
• terrestrial and aquatic locomotion
• exteroceptive sensing
• multimodal perception

Innovation

• amphibious robot
• Hall-effect sensors
• exteroceptive sensing
• salamander-inspired locomotion
• multimodal feedback control