New Robotic Jellyfish for Coral Reef Monitoring
Engineers at Florida Atlantic University (FAU) have launched a new robotic drone designed to function with the characteristics of a jellyfish.
The paper by Erik D Engeberg, published in the IOPScience online journal, describes the successful testing of a 20cm-wide robotic jellyfish which is able to freely swim, steer and manoeuvre itself through tight spaces.
The drone is propelled through the water by a series of eight flexible, pneumatically operated tentacles. The design is based around that of a moon jellyfish (Aurelia aurita) in its larval stage. The composite material tentacles, arranged radially around the central motor, flex in the same manner as a jellyfish's bell to generate thrust.
Jellyfish are often thought of as relatively powerless, drifting through the ocean wherever the tide and currents should take them. They are, however, remarkably efficient swimmers. The movement of a jellyfish's bell generates thrust via a combination of factors, including a rudimentary form of jet propulsion. Jellyfish can also change direction quite rapidly by altering the shape of the bell as it flexes.
Based on the principles of nature, FAU's jellyfish alternately pumps water into the soft tentacles which then contract and expel the water when power to the pump is removed. Altering the power of the pump to individual tentacles allow the bell to deform and the drone to alter direction.
Jellyfish based designs are not new, with a previous version - 'Robojelly' - having been presented by scientists at Virginia Tech and the University of Texas in Dallas in 2012. The Florida Atlantic University model, however, is the first to swim independently and untethered through the water column.
Soft material design for underwater drones is increasingly gaining attention as a solution to the method of monitoring the world's oceans while minimising the damage that could be caused by rigid, propeller-driven machines. Earlier this year, researchers at the Massachusetts Institute of Technolgy (MIT) Computer Science and Artificial Intelligence Laboratory (CSAIL) launched 'SoFi', a soft robotic fish capable of independently swimming around coral reefs.
One concern that has been raised about the new robotic jellyfish is that its small size and similarity to living species of jellyfish may cause turtles to mistake it as a source of prey. Turtles are known to consume plastic bags for exactly the same reason.
The paper does not specifically mention how the drone might counteract accidental predation, however, it has been suggested that an acoustic deterrent might be added, or a chemical to make the robotic jellyfish 'unpalatable' to turtles.