Soft Robot Uses Mechanical Intelligence to Switch Swimming Modes

People's Daily reported that a team from North Carolina State University developed a mechanically intelligent soft robot capable of shifting among jellyfish, fish, and rotor swimming modes using only two pneumatic tubes for inflation and deflation. The system avoids microcomputers and real-time algorithms, embedding control logic directly into its physical structure to execute actions like rising, hovering, and steering, according to findings published in Science Advances. The prototype measures 55 millimeters in length, weighs 14.5 grams, and features an octagonal central frame connected to four flexible triangular arms alongside ultra-soft flat silicone bladders that form dual-channel pneumatic actuators. Each arm uses a monostable arrangement resembling a spring door, snapping downward during inflation to release elastic energy and snapping back within roughly 26 milliseconds upon deflation. Operating both pneumatic channels together enables the robot to flap all four arms synchronously for vertical jellyfish-style propulsion, hovering, and descending, while powering one side generates directional fish-like swimming. Alternating inflation across the two channels with a 180-degree phase difference drives alternating arm flaps, causing the robot to spiral upward in place in rotor mode.

The current prototype still requires manual configuration of inflation frequency and phase, lacking real-time perception or onboard decision-making. Mode shifts retain residual angular momentum that disturbs directional swimming, and the set physical geometry restricts the device's overall adaptability across varied operational tasks.