A swimming robotic tool has been designed for monitoring coral reefs and other fragile marine ecosystems. The 3D printed biomimetic soft robots, based on the shape of larval moon jellyfish, are equipped with hydraulic networks for propulsion.
This motive mechanism was selected by researchers from Florida Atlantic University (FAU) and the U.S. Office of Naval Research to prevent inadvertent damage to delicate ecosystems. Water is used to inflate the hydraulic network actuator so as to replicate the neutral buoyancy of jellyfish.
Five different robot jellyfish were 3D printed using silicon rubber for the actuators. A cylindrical housing for the jellyfish microcontroller and electronics was also 3D printed. Each device was fabricated with a varying rubber hardness to test the effect it had on the propulsion efficiency. Two impeller pumps inflate the eight tentacles, delivering water from the environment into the soft actuators to produce a swimming stroke. When the pumps are not powered, the elasticity of the tentacle actuator silicon rubber material constricts the actuators to push the water back into the environment during the relaxation phase. The design eliminated the need for valves, thereby reducing control complexity, space requirements and cost.
The devices are able to swim freely and steer from side to side. The robots' ability to squeeze through narrow openings was also demonstrated, using circular holes cut in a plexiglass plate.
The planned addition of environmental sensors such as sonar into the robot's control algorithm, along with a navigational algorithm, is expected to enable the jellyfish to detect gaps and determine if it can swim through them.
The research is published in Bioinspiration & Biomimetics.