Snapp: An Agile Robotic Fish with 3-D Maneuverability for Open Water Swim

TL;DR

Snapp is an innovative robotic fish designed for open water, demonstrating high speed and full 3D maneuverability through a novel propulsion and steering mechanism, outperforming previous designs in complex aquatic environments.

Contribution

The paper introduces Snapp, a robotic fish with a new cyclic-differential propulsion method enabling fast, agile swimming and complex maneuvers in open water, advancing robotic fish capabilities.

Findings

Achieved swimming speeds of 1.5 m/s (1.7 body lengths/sec)

Performed complex maneuvers like figure-8 and S-shape trajectories

Instantaneous yaw changes of 15° in 0.4 s

Abstract

Fish exhibit impressive locomotive performance and agility in complex underwater environments, using their undulating tails and pectoral fins for propulsion and maneuverability. Replicating these abilities in robotic fish is challenging; existing designs focus on either fast swimming or directional control at limited speeds, mainly within a confined environment. To address these limitations, we designed Snapp, an integrated robotic fish capable of swimming in open water with high speeds and full 3-dimensional maneuverability. A novel cyclic-differential method is layered on the mechanism. It integrates propulsion and yaw-steering for fast course corrections. Two independent pectoral fins provide pitch and roll control. We evaluated Snapp in open water environments. We demonstrated significant improvements in speed and maneuverability, achieving swimming speeds of 1.5 m/s (1.7 Body Lengths per second) and performing complex maneuvers, such as a figure-8 and S-shape trajectory. Instantaneous yaw changes of 15$^{\circ}$ in 0.4 s, a minimum turn radius of 0.85 m, and maximum pitch and roll rates of 3.5 rad/s and 1 rad/s, respectively, were recorded. Our results suggest that Snapp's swimming capabilities have excellent practical prospects for open seas and contribute significantly to developing agile robotic fishes.