Although jellyfish may not be the fastest animals in the ocean, they do swim in an energy-efficient manner – a manner that underwater robots might do well to copy. With that in mind, Chinese scientists have created a robotic jellyfish, that may someday autonomously explore the briny depths.

Real jellyfish swim by jet propulsion, expanding and contracting their bell-shaped bodies to push water out behind them. And while we have previously seen underwater robots that emulate this technique, most of them have had to be tethered to a surface-located power source and/or control system. Researchers from the Chinese Academy of Sciences in Beijing decided to address that situation, designing a free-swimming robo-jelly.

Modelled after the large Aurelia aurita (or "moon jellyfish"), the device features a bell-shaped rigid head along with a cylindrical body underneath. The latter is covered in a soft rubber skin, and incorporates four separate six-bar linkage mechanisms.

Forward motion is achieved by bending and straightening those mechanisms (kind of like fingers), causing the body to push out water as it expands and contracts. Additionally, by moving two weights located in its body cavity, the robot is able to be steered both vertically and horizontally.

The scientists are now developing reinforcement-learning-based software, that would allow the device to learn which weight movements result in which changes in direction. Assisted by various onboard sensors, the robot could then move through the water along a given course while avoiding obstacles, without any human control. It could even carry small payloads, such as environmental sensors, while doing so.

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