Yangwei Wang’s research while affiliated with Harbin Institute of Technology and other places

The cuttlefish have higher swimming speed and more maneuverability than most of the fish mainly benefiting from their unique jet propulsion mechanism, which is realized by the contraction and expansion of their flexible mantle. However it is difficult to mimic this jet propulsion mechanism using conventional electro-mechanical structures. In this paper, the musculature of the cuttlefish mantle and how the mantle flexibly contracts and expands were analyzed first. Then the Shape Memory Alloy(SMA) wires were chosen as the actuators and the soft silica gel was chosen as the body materials to develop a biomimetic mantle jet propeller. The SMA wires were embedded within the soft silica gel formed with cuttlefish mantle shape along the annular direction to mimic the circular muscles of cuttlefish mantle. The water was squeezed out the mantle cavity to form rear jets when the biomimetic mantle was contracted by SMA wires. A mechanical model and a thermal model were established to analyze the jet thrust and the jetting frequency. Theoretical analysis shows that the jet thrust is proportional to the square of the rate of change of SMA strain. Increasing the driving voltage can improve the rate of change of SMA strain, thus can improve both the jet thrust and the jetting frequency. However the jetting frequency is mainly restricted by the cooling of SMA wires. To maximize the jetting frequency, the optimal driving parameters for different driving voltage were calculated. The propulsion performance was tested and the results show that the jet thrust can increase with the driving voltage as predicted and the maximum average jet thrust is 0.14 N when the driving voltage is 25 V. The swimming test was carried out to verify the feasibility of the novel design. It is shown that the biomimetic jet propeller can swim with higher speed as the jet thrust and jetting frequency increase and the maximum speed can reach 8.76 cm·s−1 (0.35 BL·s−1) at a jetting frequency of 0.83 Hz.

Cuttlefish can swim with great maneuverability by undulating their fins and can swim with high speed by jetting. To mimic the muscle structure of the cuttlefish, a kind of flexible fin unit which can bend to both sides and a kind of biomimetic mantle which can flexibly contract and expand, are developed with the structure that SMA (shape memory alloy) wires are embedded into the flexible silicone rubber. Then a kind of biomimetic undulating fin and a kind of biomimetic jet propeller based on the former design are developed to mimic the swimming mechanism of cuttlefish. And the thrust performance of both of the propellers is tested. At last, a prototype of biomimetic cuttlefish robot is developed and the swimming experiments are carried out.

The paper presents a vehicle with a biomimetic level pectoral fin. Firstly, muscle structure of cuttlefish's pectoral fin is analyzed, and undulatory movement of cuttlefish's pectoral fin is simplified. Meanwhile a kinematics model is built for hydromechanics theory analysis. Secondly, a vehicle with a biomimetic level pectoral fin based on a flexible fin unit actuated by shape memory alloy (SMA) wires is designed. Finally, swimming performances is experimented. Experimental results show that the vehicle can realize undulatory swimming by the biomimetic pectoral fin. The swimming speed and theoretical thrust increase with the heating pulse width. The maximum swimming speeds is up to 33 mm/s.

A flexible noiseless and high-efficient propulsor plays a prominent role in the performance of underwater vehicles. This paper presents a micro flexible caudal fin propulsor actuated by shape memory alloy (SMA) wires. To improve the responding frequency and fatigue of the SMA wires, a pair of slots is designed. So the SMA wires can be heated in the protection of silica ~ellayer and cool in the other status, i.e. flowing water. Then the propulsive performance of the biomimetic propulsor is evaluated through thrust measurement experiments. Note that higher undulating frequency does not mean stronger thrust force because the undulating amplitude descends along with the undulating frequency increase for this kind SMA propulsor. Further, the kinematics of the propulsor is analyzed and the corresponding equation of motion is obtained. At last, a three-dimensional numerical simulation on the biomimetic fin was conducted by CFD to investigate the interaction of the propulsor with surrounding water and the thrust production. The CFD results consist with the experimental results well, which verify the kinetic model and the numerical simlation.

Inspired by caudal fin used for propulsion in most bony fishes, a micro flexible caudal fin-like propulsor actuated by shape memory alloy (SMA) wires is designed and presented. Bending experiment of the caudal fin-like propulsor is done to verify the concept. Then the propulsive performance of the caudal fin-like propulsor is evaluated through thrust force measurement experiments. Meanwhile, the variation of the thrust force with respect to the driven parameters of the caudal fin is studied. At last, a micro robot fish based on the propulsor is fabricated and the swimming capability was evaluated.

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 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.

An improved initial rotor position estimation method based on signal injection for position sensorless interior permanent magnet synchronous motor (PMSM) at standstill is presented. In first step, high-frequency rotating voltage signal is injected into stator wingding to obtain magnetic pole position. A PI tracing observer is used to regulate the error signal containing magnetic pole position information. When the error signal is regulated to zero, magnetic pole position can be estimated. In second step, in order to identify magnet polarity more easily, two pulse voltage vectors are injected based on the obtained position information in first step. By comparing d-axis stator current values, magnet polarity can be identified. Then the position estimated in the first step can be compensated according to the magnet polarity information. The validity of the proposed estimation scheme is verified by a 22 kW interior PMSM. Experimental results show that the method can achieve acceptable estimation accuracy.

A biomimetic manta ray robot fish actuated by shape memory alloy (SMA) wires is presented. The robot fish is propelled by oscillation of a pair of flexible pectoral fins, and swims like a kind of rajiform model. Firstly, swimming characteristic of manta ray is analyzed and a simple kinematic model of manta ray flexible pectoral fin is built. Secondly, the intelligent materials for simulating the muscle motion of manta ray are analyzed. Finally, the flexible biomimetic pectoral fin actuated by SMA wires, the biomimetic manta ray robot fish is developed, and the thermodynamics analysis on SMA wire is performed to optimize the control rule of SMA wire. The biomimetic manta ray robot fish is similar to manta ray in shape. It also has a flat-form body and a pair of triangular flexible pectoral fins. Its maximal swimming speed in line is 79 mm/s. Its minimum turning radius is 118 mm. It can swim stealthily with good stability.

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.