An untethered soft robotic fish using SMA wires and its performance analysis

The authors have developed a bionic robotic fish having a soft tail by employing intelligent materials as actuators. Two sets of shape memory alloy (SMA) wires are stitched to the two sides of the soft tail, allowing the tail to bend on either side. The designed structure is expected to have the ability to mimic the straight swimming posture of a real fish in the water, and also to turn left and right using the soft body and caudal fins (BCF propulsion). The body and the head part are designed by a 3D CAD software, whose streamline ability is verified through the fluid simulation, and are printed by a high-precision 3D printer. A micro Arduino computer is set inside the fish body for the total swimming control. The infrared (IR) communication is also installed for the detailed analysis of the swimming motion and the speed. By studying the relationship between the control signals and the swimming behaviour of the robotic fish, the performance of the swimming motion was examined for determining the parameter values to realise real-fish swimming.