An Untethered Bioinspired Robotic Tensegrity Dolphin with Multi-Flexibility Design for Aquatic Locomotion

TL;DR

The paper provides insights into how a few such variations affect robot motion and efficiency, measured by speed and cost of transport (COT), and demonstrates the potential of achieving dolphin-like motion through enhanced flexibility in bio-inspired robotics.

Abstract

This paper presents the first steps toward a soft dolphin robot using a bio-inspired approach to mimic dolphin flexibility. The current dolphin robot uses a minimalist approach, with only two actuated cable-driven degrees of freedom actuated by a pair of motors. The actuated tail moves up and down in a swimming motion, but this first proof of concept does not permit controlled turns of the robot. While existing robotic dolphins typically use revolute joints to articulate rigid bodies, our design -- which will be made opensource -- incorporates a flexible tail with tunable silicone skin and actuation flexibility via a cable-driven system, which mimics muscle dynamics and design flexibility with a tunable skeleton structure. The design is also tunable since the backbone can be easily printed in various geometries. The paper provides insights into how a few such variations affect robot motion and efficiency, measured by speed and cost of transport (COT). This approach demonstrates the potential of achieving dolphin-like motion through enhanced flexibility in bio-inspired robotics.

Figures (13)

• Figure 1: Overview of the dolphin robot: (a)(i) Side view of CAD model, (a)(ii) Side view of the real robot, (b) Dolphin robot showing inner skeleton, (c) Top view of CAD model, (d)(i) Swimming with tail down, (d)(ii) Side view of the real dolphin robot swimming with tail up.
• Figure 2: 3D Dolphin Model: (a) Side view, (b) Front view, (c) Top view, and (d) Oblique view.
• Figure 3: Silicone Tail Molding and Demolding Process: (a) Molding steps: (i) Measuring silicone solutions, (ii) Stirring the mixture, (iii) Vacuum chamber treatment; (b) Mold preparation: (i) 3D-printed mold components, (ii) Pre-assembled mold; (c) Pouring silicone into the mold. Demolding the Silicone Tail: (d) Tail during demolding; (e) Final views of the tail: (i) Left view, (ii) Front view, (iii) Side view showing the two air chambers, (iv) Sealing the air chambers for waterproofing and buoyancy.
• Figure 4: Force-displacement analysis of the silicone used for the dolphin’s tail, conducted using an Instron machine.
• Figure 5: Rigid head of our robotic dolphin: (a) Bottom view showing the wireless charging coil, and (b) The head charging on a Qi wireless charger, with the red indicator light illuminated.