RoboSalps marine bot can operate in extra-terrestrial oceans

A team at Bristol University has developed ‘RoboSalps’, a marine robot inspired by the jellyfish-like salp zooplankton.

Two RoboSalps swimming together
Two RoboSalps swimming together - Valentina Lo Gatto

Salps belong to the Tunicata family and have a complex life cycle, changing between solitary and aggregate generations where they connect to form colonies. Their semi-transparent, barrel-shaped bodies inspired the tubular bodies of Bristol’s RoboSalps.

RoboSalps has been engineered to operate in unknown and extreme environments, taking inspiration from its animal namesake. The robot’s bodies can link to each other to form ‘colonies’, the team said, giving them new capabilities through working together.

Valentina Lo Gatto, of Bristol’s Department of Aerospace Engineering, is leading the study. She is also a student at the EPSRC Centre of Doctoral Training in Future Autonomous and Robotic Systems (FARSCOPE CDT).

Lo Gatto explained that each robotic module is made of a lightweight soft tubular structure and a drone propeller which enables them to swim independently. Combining to form ‘colonies’ makes them more robust and able to carry out complex tasks, she explained.

“Because of their low weight and their robustness, they are ideal for extra-terrestrial underwater exploration missions, for example, in the subsurface ocean on the Jupiter moon Europa,” Lo Gatto said.

According to the team, the relatively novel concept of a soft robot colony has a wide range of interesting applications. RoboSalps are potentially quite energy efficient, researchers said, and robust due to inherent redundancy – if one module breaks, the whole colony can still move. This could make them ideal for autonomous missions where a direct and immediate human control might not be feasible.

Dr Helmut Hauser, of Bristol’s Department of Engineering Maths, said that these include the exploration of remote submarine environments, sewage tunnels, and industrial cooling systems as well as extra-terrestrial missions.

“They can easily be stored in a reduced volume, ideal for reducing global space mission payloads,” Hauser said.

A compliant body also provides safer interaction with potentially delicate ecosystems, both on earth and extra-terrestrial, reducing the risk of environmental damage.

The possibility to detach units or segments and rearrange them also gives the system adaptability: once the target environment is reached the colony could be deployed to start its exploration. At a certain point, it could detach into multiple segments, each exploring in a different direction, and afterwards reassemble in a new configuration to achieve a different objective such as manipulation or sample collection.

Prof. Jonathan Rossiter, also of Bristol’s Department of Engineering Maths, added that the team is developing control approaches that can exploit the compliance of the modules, with the goal of achieving energy efficient movements close to those observed in biological salps.