A novel biomimetic jellyfish robot based on a Soft and Smart Modular Structure (SMS)

This paper introduces the design, fabrication and experiment of a biomimetic jellyfish robot based on a soft and smart modular structure (SMS) to mimic the behavior of the alternating shrinkage and expansion of the real jellyfish. The SMS consisted of two layers including an actuating layer and a recovery layer. And to mimic the actinomorphic structure of the jellyfish, the jellyfish robot had six SMSs or tentacles symmetrically extending from its central disc and a bell covering the SMSs and one central disc. We measured the force acting on the end of the SMS and results showed the force was around 1N and varied with the input current. The force increased as the heating input current increased, and the amplitude of the force gradually reduced and stabilized. Besides, the vertical floating displacements of the jellyfish robot at different frequencies were measured. As results showed that, the floating velocity of the robot was variable. The robot was able to achieve the maximum velocity of 111 mm/s at the frequency of 1.0 Hz, about 1.6 body length per second. Compared with current state of the art of robotic jellyfish actuated by smart actuators, the jellyfish robot achieved the most proficiency at 1.6 s-1. In the case where SMSs were actuated at 1.0 Hz, robot shows better performance in comparison with other frequencies based on the Strouhal Number. Finally, the jellyfish robot was able to accomplish three-dimensional locomotion with the input of sequential pattern..