Large robotic jellyfish may one day patrol the ocean floors
29 March 2013
The research team that developed the human hand sized 'RoboJelly' has unveiled a life-like, autonomous robotic jellyfish the size and weight of a grown man.
Students test the man-sized jellyfish-like robot under water
The prototype robot, nicknamed 'Cyro', is a larger model of a robotic jellyfish the same team from Virginia Tech College of Engineering (headed by Virginia Tech's Professor Shashank Priya) unveiled in 2012. The earlier robot, dubbed 'RoboJelly', is roughly the size of a man’s hand.
“A larger vehicle will allow for more payload, longer duration and longer range of operation,” said Alex Villanueva, a Canadian mechanical engineering student working with Priya. “Biological and engineering results show that larger vehicles have a lower cost of transport, which is a metric used to determine how much energy is spent for travelling.”
Both robots are part of a multi-university, nationwide $5m project funded by the US Naval Undersea Warfare Centre and the US Office of Naval Research. The goal is to place self-powering, autonomous machines in waters for the purposes of surveillance and monitoring the environment, in addition to other uses such as studying aquatic life, mapping ocean floors, and monitoring ocean currents.
Cyro is modelled and named after the jellyfish cyanea capillata. As with its predecessor, this robot is in the prototype stage, years away from use in waters. A new prototype model is already under construction at Virginia Tech’s Durham Hall, where Priya’s Centre for Energy Harvesting Materials and Systems is based.
“We hope to improve on this robot and reduce power consumption and improve swimming performance as well as better mimic the morphology of the natural jellyfish,” Villanueva said. “Our hopes for Cyro’s future is that it will help understand how the propulsion mechanism of such animal scales with size.”
A stark difference exists between the larger and smaller robots. Cyro is powered by a rechargeable nickel metal hydride battery, whereas the smaller models were tethered. Experiments have also been conducted on powering jellyfish with hydrogen but there is still much research to be done in that area.
In both cases, the jellyfish must operate autonomously for months or longer at a time.
“Cyro showed its ability to swim autonomously while maintaining a similar physical appearance and kinematics as the natural species.
Teh robot's body consists of a rigid support structure with direct current electric motors to control the mechanical arms that are used in conjunction with an artificial mesoglea, or jelly-based pulp of the fish’s body, to create hydrodynamic movement.
With no central nervous system, jellyfish instead use a diffused nerve net to control movement and can complete complex functions. A parallel study on a bio-inspired control system is in progress which will eventually replace the present controller.
As with the smaller models, Cyro’s skin cmoprises a thick layer of silicone placed over a bowl-shaped device containing the electronic equipment. When moving, the skin floats and moves with the robot, and looks very lifelike.