Zhenlong Wang

A micro biomimetic manta ray robot fish actuated by SMA

The paper presented a design of a micro biomimetic manta ray robot fish actuated by shape memory alloy (SMA) wire, verified that SMA wire is a feasible actuator. The robot fish is quitely similar to manta ray in shape. It also have a flat-form body and a pair of triangular flexible pectoral fins. In our experiment, we researched the flexible pectoral fin shape change, and then the forward swimming and turning swimming performance were evaluated. We also give the results of the robot fishs speed and amplitude in different actuating pulse width. It can swim with good stability and stealthily. The micro biomimetic manta ray robot fish is suitable to do investigation in narrow space of the ocean.

Initial Design of a Biomimetic Cuttlefish Robot Actuated by SMA Wires

This article describes the initial design of a biomimetic cuttlefish robot. The robot has a similar streamlined shape as cuttlefish, propelled by the complex of the biomimetic undulatory level pectoral fin and the water-jetting. Firstly, the morphology and swimming theory of cuttlefish is analyzed. Secondly, the overall structure of the biomimetic cuttlefish robot is designed and the three-dimensional model is simulated by software FLUENT. Finally, the biomimetic level pectoral fin and the biomimetic mantle actuated by SMA wires are designed. The propulsive thrust and the propulsive efficiency are analyzed. The results show that the robot has good hydrodynamic performance, can achieve slow swimming speed with high efficiency by the level pectoral fin. When the swimming speed is 0.18 m/s, the propulsive fore is 0.047 N, the propulsive efficiency is 89 %. It can also achieve high swimming speed relying on jetting propulsion. The maximum propulsive force is 0.79 N and the maximum swimming speed is above 0.6 m/s, the propulsive efficiency is 31 %.

A flexible hingeless control surface inspired by aquatic animals

A flexible hingeless control surface model was proposed for motion control of Underwater Vehicles (UVs), which is inspired by the flexible bending control surfaces of underwater creatures, such as fish and squid. Computational Fluid Dynamics (CFD) simulation demonstrates that, in comparison with the hinged or rigid control surface, the proposed flexible bending control surface can suppress the flow separation so as to improve the turning performance. A prototype of the flexible control surface was fabricated, in which Shape Memory Alloy (SMA) wires were selected as the actuators. The elastic energy storage and exchange mechanism was incorporated into the actuation of the control surface to improve the efficiency. Thermal analysis of SMA wires was performed to find proper actuating condition. Open-loop bending experiments were carried out. The results show that the proposed control surface can achieve the maximum bending angle of 104°. Moreover, the power and energy consumption under different pulse conditions were compared.

2D-numerical simulation of flexible oscillating fin mimetic bony fishes fin

A controllable flexible biomimetic fin actuated by Shape Memory Alloy (SMA) was presented to imitate the flexible bending of fin rays in bony fishes. Based on the bending experiment of the biomimetic fin, the kinematics model was set up. Then a two-dimensional numerical simulation on the oscillatory biomimetic fin was performed by computational fluid dynamic to investigate the interaction with the surrounding fluid and the propulsive force production. By solving the 2D, incompressible, laminar, unsteady Navier-Stokes equations, the computational results show that the biomimetic fin generates a vortex ring after a complete period in still water which can generate a thrust force. The dynamics performance of the vortex ring is achieved and then the average propulsive force is calculated on different oscillatory frequencies and maximum bending angles to find the change character. At last, an important parameter, the Strouhal number was discussed in this paper. Different Wake pattern were observed depending on different velocities of the background flow, which decide the Strouhal number. When the 0.2<St<0.3, the wake shows evidence of an approximate momentum balance.