Fig.1: (L -R): Polycarbonate skeleton of robot, testing apparatus, fully blown membrane
Scientists in Singapore have developed a new octopus-inspired robot which can zip through water 10 times its body length within one second, in an ultra-efficient manner. This first-ever ultra-fast propulsion and super-manoeuvrability demonstrated in underwater vehicles is unprecedented; and is the work of researchers and an engineer from the Singapore-MIT Alliance for Research and Technology (SMART) [新加坡-麻省理工学院科研中心]. The first author, originally from SMART, is now with the University of Southampton.
This ground-breaking research was published in Bioinspiration & Biomemetics and Nature.com in Feb 2015 (and featured in AsiaOne - Deep-sea robots set to make waves and Phys.org - Octopus-inspired robot - the fastest underwater robot based on given power), and validates the physics of shape change (that forms the basis of jet propulsion of cephalopods) to give additional thrust to underwater vehicles.
Inspired by the speed at which cephalopods like the octopus, flee from danger by inflating its mantle cavity with water to a bluff-body shape and then quickly expelling it to dart away, the researchers started building an octopus-inspired robot in November 2013.
The end result is a polycarbonate 3D printed streamlined skeleton which had no moving parts (Fig.1) and no energy storage device other than a thin elastic outer membrane. It works like blowing up a balloon and then releasing it to fly around the room. The 27-cm long robot is inflated with water and once released, rapidly deflates by shooting the water out through an aperture at its base to power its propulsion. As the rocket contracts, it can achieve more than 2.6 times the thrust of a rigid rocket doing the same manoeuvre, while creating minimum turbulence – an important feature in underwater research / survey vehicles. The skeleton within the robot keeps the final shape streamlined, while fins at the tail, help in stabilization. See News Release/Factsheet for more.