Polymander II: an amphibious salamander-inspired robot with contact and flow sensors
Qiyuan Fu, Sudong Lee, Andrea Grillo, Jonathan Arreguit, Louis Gevers, Josie Hughes, Auke Ijspeert
AI summary
Problem
Most amphibious robots lack the ability to simultaneously sense terrestrial and aquatic interactions due to the difficulty of waterproofing force sensors without adding bulk. This sensory gap hinders the development of robust, feedback-driven controllers for complex multimodal locomotion.
Approach
The authors designed lightweight Hall-effect sensors to detect foot contact and lateral water flow forces, integrating them into a salamander-inspired robot with a custom high-speed serial bus and a flexible TPU dry suit for reliable waterproofing.
Key results
- High-frequency (500+ Hz) simultaneous acquisition of foot contact and hydrodynamic forces
- Novel transparent TPU dry suit and custom sealing mechanisms enabling flexible, leak-proof waterproofing
- Custom masterless token-ring communication protocol reducing latency across distributed sensor modules
- Demonstrated smooth walking-to-swimming transitions using real-time force feedback for multimodal coordination
Why it matters
Provides a practical sensing and waterproofing framework for developing advanced feedback controllers in amphibious robotics, advancing autonomous operations in challenging land-water environments.
Abstract
Robots benefit from sensory information to coor- dinate 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.