A Bionic Piezoelectric Robotic Jellyfish With a Large Deformation Flexure Hinge

Jellyfish are one of the underwater creatures that have been imitated by underwater bionic robots, but a current challenge to create a bionic jellyfish is with the use of piezoelectric ceramic sheets as the driving element, due to their small output displacement. Here, a bionic robotic jellyfish with three tentacles is presented that is driven by three piezoelectric beams, and to transmit power, a large deformation composite flexure hinge is created which employs fishing line embedded in a 3-D-printed structure. In addition, the structure design and fabrication of the drive system are described. A dynamic model of the drive system is established to solve for the working mode, forced displacement responses, and swimming lift. A series of experiments are carried out to verify the theoretical analysis and validate the design of the robotic jellyfish. The proposed robotic jellyfish has a total mass of 29.4 g, tentacle spread of about 150 mm, and an overall height of 100 mm. The robotic jellyfish can exhibit swimming performance with drive frequencies of 0.7–1.1 Hz, and the best achieved swimming speed was 10 mm/s. These design, modeling, and fabrication methods may be beneficial and inspiring for the future development of the micro soft robot.