The underwater robots of the future may not look like robots at all. With recent advances in artificial muscle technology, it is now possible to ditch the electric motors traditionally used in autonomous underwater vehicles (AUVs) for soft, silent propulsion systems inspired by biology. The Bio Inspired Covert Electrostatic Propulsor (BICEP) — recently seen swimming in Portage Bay near the University of Washington campus in Seattle, Washington, uses artificial muscles to oscillate a fish-like tail silently through the water. The platform, colloquially known as "Fishbot", has been developed by a university–government–industry research collaboration among APL-UW, the Naval Undersea Warfare Center Division Newport (NUWCDIVNPT), and Colorado startup Artimus Robotics.

"We're taking soft robotics out of the lab and into the real world," says project lead Tom Hansen, whose team is supported by the Office of Naval Research's Bio-Inspired Autonomous Systems Program. At the core of this system are Hydraulically Amplified Self-Healing Electrostatic (HASEL) artificial muscles, developed by Artimus Robotics. Unlike conventional motors, these artificial muscles are nearly neutrally buoyant and inherently pressure tolerant, meaning they can operate at extreme ocean depths without bulky buoyant foam or thick metal pressure vessels — a major advantage for vehicle design. In addition to proving the muscles could work at depth, and for extended periods of time, the team conducted acoustic and magnetic testing, which validated that these muscles would be extremely hard to detect by underwater sensing systems. "It is going to be very difficult to discern this system from other fish, whales, or whatever form factor the AUV takes," Hansen adds.

Andrew Tang and his colleagues at NUWCDIVNPT contribute expertise in translating the biomechanics of fishes into engineered systems to improve swimming performance. The NUWCDIVNPT team explored muscular hydrostats, inter-tendinous leveraging, artificial exotendon skins, and multisegmented vertebrae. BICEP isn't simply bioinspired, it is biomimetic.

The team is confident that BICEP can be competitive with conventional AUV propulsion systems, especially in applications where quiet operation and minimal environmental disturbance are critical, such as studying marine ecosystems without effecting biology or any associated sensor systems.

Next time you see a large fish swim by, you may have to give it a second look.