Jellyfish-Inspired Soft Robot Driven by Fluid Electrode Dielectric Organic Robotic Actuators.

Caleb Christianson,Guorui Li,Saurabh Jadhav,Chibuike Agba,Tiefeng Li,Ayush Giri,Michael T. Tolley,Christopher Bayag

doi:10.3389/frobt.2019.00126

Abstract

Robots for underwater exploration are typically comprised of rigid materials and driven by propellers or jet thrusters, which consume a significant amount of power. Large power consumption necessitates a sizeable battery, which limits the ability to design a small robot. Propellers and jet thrusters generate considerable noise and vibration, which is counterproductive when studying acoustic signals or studying timid species. Bioinspired soft robots provide an approach for underwater exploration in which the robots are comprised of compliant materials that can better adapt to uncertain environments and take advantage of design elements that have been optimized in nature. In previous work, we demonstrated that frameless DEAs could use fluid electrodes to apply a voltage to the film and that effective locomotion in an eel-inspired robot could be achieved without the need for a rigid frame. However, the robot required an off-board power supply and a non-trivial control signal to achieve propulsion. To develop an untethered soft swimming robot powered by DEAs, we drew inspiration from the jellyfish and attached a ring of frameless DEAs to an inextensible layer to generate a unimorph structure that curves toward the passive side to generate power stroke, and efficiently recovers the original configuration as the robot coasts. This swimming strategy simplified the control system and allowed us to develop a soft robot capable of untethered swimming at an average speed of 3.2 mm/s and a cost of transport of 35. This work demonstrates the feasibility of using DEAs with fluid electrodes for low power, silent operation in underwater environments.

Highlights

Robots are being used in increasing numbers for underwater exploration and environmental monitoring (Dunbabin and Marques, 2012) and will continue to serve as a valuable data collection tool for scientists (Wynn et al, 2014)
We developed a low power, silent, soft, jellyfishinspired robot driven by fluid electrode dielectric organic robotic actuators (FEDORAs)
As with our previous work using fluid electrodes (Christianson et al, 2018a,b), the FEDORAs actuate completely silently as opposed to traditional ROVs that rely on propeller or jet propulsion, enabling stealthy locomotion

Summary

Introduction

Robots are being used in increasing numbers for underwater exploration and environmental monitoring (Dunbabin and Marques, 2012) and will continue to serve as a valuable data collection tool for scientists (Wynn et al, 2014). Underwater robots are usually driven by propellers or jet thrusters, which generate considerable noise and vibration This additional noise is especially problematic when studying elusive animals or when studying underwater acoustics. They consume a large amount of Jellyfish-Inspired Robot Driven by FEDORAs power, requiring considerable batteries or a tether. The jellyfish primarily expends energy during the contraction phase in which energy not transferred to the fluid can be stored in the elastic structure, and the stored energy can be recovered during the relaxation phase of the swimming cycle This approach of passive relaxation enables the jellyfish to achieve such high efficiency. The pulse frequency at which jellyfish swim is inversely proportional to their mass, and they reduce their pulse frequency as they grow to reduce the energetic cost of driving a large mass at a high frequency (McHenry, 2003)

Results

Discussion

Conclusion