Abstract
Biologically inspired soft robots that are mass manufacturable and have silent operation are needed for safe robot-animal interactions. Although electrothermal soft actuators employed in jellyfish-inspired robots have shown promise, they suffer major drawbacks like high power consumption and low actuation frequency. Here, we present a 3D printed jellyfish robot, Jelly-Z 2.0, actuated with three novel self-coiled twisted and coiled polymer (TCPFL) coated with a solution composed of carbon nanotube/mesoporous carbon/ nickel / polyvinyl alcohol (CNT-C-Ni-PVA). The soft structure of the jellyfish is additively manufactured using silicone 3D printing in a custom-made 3D printer and embedding with inelastic membrane. Silicone additive manufacturing technology requires ∼70 % less manufacturing time and allows for the mass manufacturing of controlled geometry of jellyfish robot bell, which is superior to traditional casting methods. The novel actuators, CNT-C-Ni-PVA coated self-coiled TCPFL are characterized both in air and underwater. It is ∼140 % more efficient than non-coated TCPFL in water and ∼53 % more efficient in air. These actuators are capable of fast actuation at 2 Hz, producing cyclic actuation while consuming ∼35 % less power and actuating ∼83 % more in water for same power input than non-coated. This actuator has an actuation contractile efficiency calculated is ∼0.012 % in underwater water conditions and 0.02% in air. Jelly-Z 2.0 was tested at five different frequencies (0.33 Hz, to 2 Hz), showing a maximum swimming speed of 7.4 mm/s. In terms of cost of transport (COT), this jellyfish robot performs as one of the best amongst all electrothermally actuated jellyfish robots in the literature. A closed-loop PID control system on these novel actuators has also been investigated as well.
