Squid fin-like propeller based on the principle of muscular hydrostat

A squid fin-like propeller based on the principle of muscular hydrostat is presented. The propeller, which can simulate the movements of squid fin, consists of propeller module, remote control module, driving module and a battery unit. The propeller module contains 2 horizontal fins, and each fin consists of a membrane and 5 flexible biomimetic fins which are actuated by shape memory alloy wires. The biomimetic fin mimics the structure of the squid/cuttlefish fin and can bend flexibly. During the action of biomimetic fin, elastic mechanism is incorporated to improve its performance by storing elastic energy during bending and releasing elastic energy during return. Thermal analysis of shape memory alloy wire in biomimetic fin was performed and it is found that for the biomimetic fin, large bending angle can be got at high frequency by applying short-width, heavy-current pulse. Bending experiments of the biomimetic fin were carried out in air and water, which validated the design and the control method of the biomimetic fin. Experiments on the squid fin-like propeller were carried out by simulating the flapping movement of short-fin squid fin. The maximum straight swimming speed and the maximum rotary speed were 40 mm/s and 22 (°)/s, respectively. This environment-friendly propeller can produce flexible movements and can be propelled quietly in water.