Robot locomotion has various solutions for land, including tracks, wheels, bipedal and quadrupedal -- some of which are purely vehicular, and some of which are inspired by animals (including humans). For aquatic robots, locomotion and shape are usually inspired by fish -- but there are other creatures in our vast oceans to draw from as well.
Consider the nimble and clever octopus, which propels itself through the water by pumping its eight limbs in a synchronised motion known as "sculling". This motion has been the subject of study for an octopus robot for some time, led by researchers at the Foundation for Research and Technology-Hellas (FORTH) in Greece.
Last year, the team published a paper detailing their research into this movement with a non-fleixble plastic octopus that snapped its limbs together stiffly; this year, they have doubled the robot's speed considerably by using flexible silicone and adding a missing feature: the webbing real octopodes have stretching between their tentacles. This serves to add thrust to the motion and increase the overall energy efficiency of the robot.
"This robotic swimmer is first investigated computationally via dynamical models capturing the arm and web compliance, and indicating the effect of various kinematic parameters of the system on its motion," the paper's abstract reads. "The performance of the robotic prototype is, then, tested experimentally, to demonstrate this novel mode of underwater propulsion by combining various patterns of sculling movements of the arms and web. Speeds of 0.5 body lengths per second and propulsive forces of up to 10.5 N were achieved, with a cost of transport as low as 0.62."
The resulting robot has since been tested in laboratory conditions and the Aegean sea, where it was followed by shoals of small fish -- indicating that the robot could be used for non-disruptive ocean life surveillance. It can also carry objects, just like a real octopus.
If big enough, could it also attack whales? Only time can tell.
Via IEEE Spectrum