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For precisely presenting the swimming behavior of fish robots underwater and the practical implementation purpose, this paper aims to investigate a well-formulated fish robot model which integrates the nonlinear rigid body dynamics, kinematics and models of actuators.

This fish robot model is mainly built up by three basic parts: a balance mechanism, a four-links vibrator and a caudal fin. In the fish robot’s head, there is a balance mechanism used to control the rotations in pitch and roll directions of the fish robot by moving two movable masses. The four-links vibrator with three active joints actuated by DC motors is designed to vibrate the fish’s body. In the end of the fish robot body, a caudal fin which connects with the passive joint is developed to generate hydrodynamic thrust forces to propel the fish robot.

From the real stability tests and control verification, it is obvious that this proposed model can precisely present the swimming behavior of fish robots and possesses the potential to develop a fish-like robotic prototype.

A well-formulated model with dynamics of actuators is integrated for presenting the swimming behavior of carangiform locomotion type fish robots in this investigation. From the simulation results and the practical test of a real fish robot, the feasibility of this proposed model for building up real fish robots can be proven, and this proposed model is accurate enough to effectively present the swimming behavior of fish robots.

The paper aims to develop a cownose ray-inspired robotic fish which can be propelled by oscillating and chordwise twisting pectoral fins.

The bionic pectoral fin which can simultaneously realize the combination of oscillating motion and chordwise twisting motion is designed based on analyzing the movement of cownose ray’s pectoral fins. The structural design and control system construction of the robotic fish are presented. Finally, a series of swimming experiments are carried out to verify the effectiveness of the design for the bionic pectoral fin.

The experimental results show that the deformation of the bionic pectoral fin can be well close to that of the cownose ray’s. The bionic pectoral fin can produce effective angle of attack, and the thrust generated can propel robotic fish effectively. Furthermore, the tests of swimming performance in the water tank show that the robotic fish can achieve a maximum forward speed of 0.43 m/s (0.94 times of body length per second) and an excellent turning maneuverability with a small radius.

The oscillating and pitching motion can be obtained simultaneously by the active control of chordwise twisting motion of the bionic pectoral fin, which can better imitate the movement of cownose ray’s pectoral fin. The designed bionic pectoral fin can provide an experimental platform for further study of the effect of the spanwise and chordwise flexibility on propulsion performance.

This paper aims to conduct a comprehensive literature review in the tidal energy physics, the ocean environment, hydrodynamics of horizontal axis tidal turbines and bio-mimicry.

The paper provides an insight of the tidal turbine blade design and need for renewable energy sources to generate electricity through clean energy sources and less CO₂ emission. The ocean environment, along with hydrodynamic design principles of a horizontal axis tidal turbine blade, is described, including theoretical maximum efficiency, blade element momentum theory and non-dimensional forces acting on tidal turbine blades.

This review gives an overview of fish locomotion identifying the attributes of the swimming like lift-based thrust propulsion, the locomotion driving factors: dorsal fins, caudal fins in propulsion, which enable the fish to be efficient even at low tidal velocities.

Finally, after understanding the phenomenon of caudal fin propulsion and its relationship with tidal turbine blade hydrodynamics, this review focuses on the implications of bio-mimicking a curved caudal fin to design an efficient horizontal axis tidal turbine.

This paper aims to develop a novel type of bionic underwater robot (BUR) with multi-flexible caudal fins. With the coordinate movement of multi-caudal fins, BUR will combine the undulation propulsion mode of carangiform fish and jet propulsion mode of jellyfish together organically. The use of Computational Fluid Dynamics (CFD) and experimental method helps to reveal the effect of caudal fin stiffness and motion parameters on its hydrodynamic forces.

First, the prototype of BUR was given by mimicking the shape and propulsion mechanism of both carangiform fish and jellyfish. Besides, the kinematics models in both undulation and jet propulsion modes were established. Then, the effects of caudal fin stiffness on its hydrodynamic forces were investigated based on the CFD method. Finally, an experimental set-up was developed to test and verify the effects of the caudal fin stiffness on its hydrodynamic forces under different caudal fin actuation frequency and amplitude.

The results of this paper demonstrate that BUR with multi-flexible caudal fins combines the hydrodynamic characteristics of undulation and jet propulsion modes. In addition, the caudal fin with medium stiffness can generate larger thrust force and reduce the reactive power.

This paper implies that robotic fish can be equipped with both undulation and jet propulsion modes to optimize the swimming performance in the future.

This paper provides a BUR with multi-propulsion modes, which has the merits of high propulsion efficiency, high acceleration performance and overcome the head shaken problem effectively.

The purpose of this paper is to introduce the modeling and implementation of a novel multimode amphibious robot, which is used for patrol and beach garbage cleaning in the land–water transition zone.

Starting from the design idea of multimode motion, the robot innovatively integrates the guiding fin and wheel together, is driven by the same motor and can achieve multimodal motion such as land, water surface and underwater with only six actuated degrees of freedom. The robot dispenses with the transmission mechanism by directly connecting the servo motor with a reducer to the actuator, so it has the characteristics of simplifying the structure and reducing the quality. And to the best of the authors' knowledge, the design of the robot can be considered the minimal configuration of amphibious robots with the same locomotion capabilities.

Based on the classical assumptions of underwater dynamics analysis, this paper uses basic airfoil theory to analyze the dynamics of the robot’s horizontal and vertical motions and establishes its simplified dynamics model. Also, the underwater motion of the robot is simulated, and the results are in good agreement with the existing research results. Finally, to verify the feasibility of the robot, a prototype is implemented and fully evaluated by experiments. Experimental results show that the robot can reach the maximum speed of 2.5 m/s and 0.3 m/s on land and underwater, respectively, proving the effectiveness of the robot.

The robot has higher work efficiency with the powerful multimode motion, and its simplified structure makes it more stable while costing less.

This paper aims to introduce a numerical investigation of aquatic locomotion using the smoothed particle hydrodynamics (SPH) method.

To model this problem, a simple improved SPH algorithm is presented that can handle complex geometries using updatable dummy particles. The computational code is validated by solving the flow over a two-dimensional cylinder and comparing its drag coefficient for two different Reynolds numbers with those in the literature.

Additionally, the drag coefficient and vortices created behind the aquatic swimmer are quantitatively and qualitatively compared with available credential data. Afterward, the flow over an aquatic swimmer is simulated for a wide range of Reynolds and Strouhal numbers, as well as for the amplitude envelope. Moreover, comprehensive discussions on drag coefficient and vorticity patterns behind the aquatic are made.

It is found that by increasing both Reynolds and Strouhal numbers separately, the anguilliform motion approaches the self-propulsion condition; however, the vortices show different pattern with these increments.

L'activité économique des stations thermales a pris aujourd'hui un tournant important. Après des décennies de conflit entre le thermalisme et la médecine clinique et pharmacologique, les stations thermales ont reçus aujourd'hui une nouvelle mission toute aussi précise qu'importante pour l'humanité.

During the very short period of cultural evolution of mankind, the world has changed dramatically. Modern humans have modified the environment not only to satisfy their needs, but also to please their greed. The forces that are united to destroy the last wildlands for short‐term economic benefits seem to be overwhelming. However, at least in some developed countries, values, preferences and political majorities have been changing over the last two decades in favour of alternative approaches. A new multiplicity of goals has sprung up, and it will not be an easy task to reconcile the diverging interests. What makes it even more difficult is that the means, by which the different goals are to be achieved, are barely known. The scientists, whose task might be to provide tools of measurement to enable political decision‐makers to set priorities, are facing serious methodological problems. Economists have not yet found practical and acceptable ways of valuing all commodities, biologists have not yet come up with proven environmental safety standards and sociologists and philosophers are far from providing a satisfactory method of integrating environmental values into the ‘social contract’.

Underwater robots are one of the effective solutions for underwater exploration. Fish's swimming motion is more effective and efficient than propeller screw propulsion which is more popular for underwater vehicles. So far, a lot of fish‐like robots that have several actuated joints have been developed. They realize arbitrary motion by controlling the joint angles simultaneously. On the other hand, using an elastic fin may reduce the number of actuated joints and the total energy consumption. The purpose of this paper is to develop a fish‐like robot driven by a single actuator with an elastic tail fin.

Since an elastic plate appropriately bends due to the interaction to the surrounding fluid, a robot with the elastic fin can swim smoothly even though it has only a single actuated joint. However, in order to improve the swimming performances, it is required to optimize the shape of fin (width, thickness, distribution, etc.). Although computational fluid dynamics technique is one of the methods to assess the effectiveness of a certain shape of fin, it may take longer to obtain the results. Therefore, in this study, a simplified simulator is constructed and a better shape of fin is explored.

Four types of fin shape were prepared and the swimming experiments were conducted. The swimming velocity changed according to the frequency and the shape of fin. In order to find the optimal shape of fin, the simulator of five‐link model surrounded by fluid is constructed. The differences of velocity can be found according to the parameters of fin shape. The simulation showed the similar trend as the experiments although the absolute values of velocity did not correspond. It is thought that the developed simulator can estimate the relative performance of fins.

Most fish robots that have been developed so far consist of rigid links and multi‐actuated joints, which can realize arbitrary motion by controlling the joint angles simultaneously. On the other hand, using an elastic plate as a tail fin may reduce the number of actuated joints and the total energy consumption although it is not easy to realize arbitrary attitude. In this paper, a fish‐like robot driven by a single actuator with an elastic tail fin was developed. This technique makes the mechanism of a fish‐like robot simple.