These Jellyfish Robots Can Outswim the Real Things

Robots that are inspired by nature aren’t anything new, but they rarely perform better than the animals they are meant to mimic. Boston Dynamics’s Spot robot, for example, is incredibly impressive, but even it can’t begin to compete with a real dog when it comes to agility. Similarly, humanoid robots generally struggle just to balance as they walk casually across paved surfaces, and certainly can’t approach the athletic ability of an actual person. But engineers from North Carolina State University and Temple University have managed to create soft robots inspired by jellyfish that can swim faster than the real things.

Jellyfish are unique among animals, because they don’t have a traditional central nervous system. Instead, they have a sort of distributed network of nerves that lets them respond, in a very basic way, to stimuli — usually to consume prey. Until they’re presented with a stimulus, they generally just swim lazily around the ocean. The three species of jellyfish that the team used for comparison didn’t swim any faster than 30 millimeters per second on average. The robotic jellyfish they made, on the other hand, are able to maintain an average speed of 53.3 millimeters per second. The key to that performance is the unique soft robotic actuator construction.

The actuators used for these jellyfish robots, which act as artificial muscles, are constructed from three layers. The first layer is made from elastic polymer and pre-stressed so that it naturally wants to contract. The second layer is the same material, but is not stressed. The final layer contains air chambers that can be quickly inflated. Those layers were formed into a ring that naturally wants to flatten out, but which rapidly curves in on itself like a bowl when air is pumped into the final layer. That motion pushes water out and propels the robot forwards. Similar actuators can be used in other applications. The same team used the actuators to create a robotic gripper that contracts in its relaxed state, so it only requires energy when it is opened. They were also used to create a larva-like robot that could quickly crawl across a surface.