Analysis of Bio-inspired Kinematic Patterns Pectoral Fin with Shape Memory Alloy (SMA)

Abstract

Pectoral fins have received the attention of many researchers because of their important role in maneuverability underwater in the recent years. This paper presents the study of a novel flexible robotic-fin actuated and the swimming propulsion by Shape Memory Alloy (SMA) inspired by a Koi Carp. In this paper, the morphological and mechanics parameters of a koi Carp pectoral fin from a carp is first studied. The motion of the pectoral fins is analyzed, which are difficult to reproduce by artificial pectoral fins and descending and ascending, the five basic gestures of the robotic fin are well achieved by the coordinating control of the fin base and fin rays, which are relaxation, expansion, bending, cupping and undulation. Secondly, a simplified theoretical model of the SMA fin plate is derived, thermodynamics of the SMA plate and the relationship between curvature and phase transformation are analyzed. Thirdly, Dynamic modeling of a flexible SMA tail, several simulations and model experiments are conducted according to the previous computation and analyses. Consequently, the five basic gestures of the robotic fin such as relaxation; expansion; bending; cupping; undulation, are extracted from the 3D grid graph. The results of kinematic of flexible pectoral fins will provide a basis to flexible pectoral fin and butterfly-inspired underwater.