A Soft Robotic Fish Actuated by Artificial Muscle Modules (SoRoFAAM-1)

Abstract

In this paper, we present the design, fabrication, locomotion and bionic analysis of a Soft Robotic Fish Actuated by Artificial Muscle (SoRoFAAM). As a carangiform swimmer, the most important part of SoRoFAAM-1, on the motion point of view, is its tail designed around a bidirectional flexible bending actuator by layered bonding technology. This actuator is made of two artificial muscle modules based on Shape Memory Alloy (SMA) wires. Each artificial muscle module has four independent SMA-wire channels and is therefore capable of producing four different actuations. This design allows us to implement an adaptive regulated control strategy based on resistance feedback of the SMA wires to prevent them from overheating. To improve the actuation frequency to 2 Hz and the heat-dissipation ratio by 60%, we developed a round-robin heating strategy. Furthermore, the thermomechanical model of actuator is built, and the thermal transformation is analysed. The relationships between the actuation parameters and SoRoFAAM-1’s kinematic parameters are analysed. The versatility of the actuator endows SoRoFAAM-1 with cruise straight and turning abilities. Moreover, SoRoFAAM-1 has a good bionic fidelity; in particular, a maneuverability of 0.15, a head swing factor of 0.38 and a Strouhal number of 0.61.