Rather than reinventing the wheel, or perhaps the leg, robotics engineers have sought to copy the modes of transportation seen in the animal kingdom. Now to add to robotic dogs, fish and ants, we have a robot that moves like an octopus.
Cephalopods, including octopodes, have developed multiple ways of getting around. Their tentacles can be used to both swim and walk, and in an emergency cephalopods can use jet propulsion, although this becomes inefficient for larger creatures.
The robot version was built by the Foundation for Research and Technology-Hellas (FORTH) from flexible silicon webbing and presented at the International Conference on Intelligent Robots and Systems.
"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 research team claim. The cost of transport is a measure of efficiency, calculated as P/mgv where P is the power input and m, g and v represent mass, gravity and velocity respectively.
With so many species out there to draw on, the team had lots of ideas on how to improve their first prototypes. “The researchers report that the addition of a soft and supple silicone web has nearly doubled the speed of the roboctopus, and not satisfied with that, the scientists have also taught it to crawl, carry objects, and swim free in the Aegean Sea," wrote Evan Ackerman of IEEE Spectrum.
The benefits of the web are visible in the video below. Note also the capacity of the octopus to carry a ball while swimming.
Before adding the web, the octopus' cost of transport was 0.85. While the improvement is noteworthy, it should not be forgotten that humans have a COT of 0.1 when walking, and half that when cycling.
The inventors think a robot octopus could be a useful way to study marine environments, noting that fish seemed surprisingly unperturbed by their creation.
Traditional hard robots are, by definition, less flexible than softer ones, only able to bend at specific joints. Thus, they can become trapped in small spaces and easily damaged in collisions.
The moment appears to be right for these sort of flexible robots. At the same conference, a team from MIT presented a snake-like robot inspired by an octopus tentacle.
Let's just hope the robots don't get too much like their models and turn cannibal.