Research On Skating And Jumping Movement Of Robots On Water Surface Inspired By Water Strider

Water strider is a kind of aquatic insect living at the water-air interface,with agile,efficient and fast water-surface movement ability.Its extraordinary ability to move on the water surface has become the imitating object of scholars to develop robots walking on water surface.The robots imitating water striders have the characteristics of small size,high concealment,agile maneuverability,low cost,easy to realize group control,etc.By carrying different types of sensors and functional modules,the water strider robots can be used as navigate and communicate relay nodes and are capable of networking to perform tasks such as water quality monitoring,reconnaissance,aquativ search and rescue.The research on water strider robots has broad application prospects in both military and civilian fields.The research of the robots inspired by water striders not only needs to explore the mechanism of the water surface movement of the water striders,but also involves the interaction between the movement of the robot and the water-air interface.Due to the fluidity and turbulence of water,the interaction force between the robots and the water is complicated.The existing robots tend to imitate the skating and jumping motions of water striders,the performance still needs to be improved.It is still far from practical applications.With the goal of improving the performance of the robots,this paper focuses on the surface tension–dominant skating movement and water pressure-dominated jumping movement.For the surface tension–dominant robot skating on water surface,the hydrophobic mechanism analysis between the robot's leg and the water surface,and the driving method of the flexible driving legs are studied.For the water pressure-dominated jumping robot,research on the hydrodynamics of water pressure-dominated jumping robots is carried out,then a new type of jumping robot is developed on this basis.First,based on the microscopic simulation method of droplet impact on superhydrophobic surface,the microscopic mechanism between the legs of the surface tension–dominant skating robot and air-water interface is studied.The influence of the impact velocity and surface microstructure on the hydrophobicity are researched,and the hydrophobicity failure conditions during the skating process are obtained.Then based on the Young-Laplace equation,the force model of hydrophobic support legs are analyzed.The influence of the structure and size of supporting legs on the support force and drag force are analyzed.Relevant study is helpful for the design of robots' supporting system.Biological studies have shown that the flexibility of the joint-type leg structure of the water striders allows it to deform conform to the water surface.Inspired by this,based on the Euler-Bernoulli beam theory,the flexible driving legs' actuating force and spatial deformation model was established.The influence of deformation of the flexible legs on the critical rowing frequency and actuating force is analyzed.On this basis,the structure of flexible driving legs is designed,and the dynamic simulation and skating experiments of a robot equiped with different stiffness of the driving legs are conducted.The research results show that,compared with rigid driving legs,the flexible leg can effectively increase the maximum rowing frequency before piercing the water,thereby improving the skating performance of the robot.Aiming at the problem that the current force model of the water pressure-dominated jumping robot-water interaction is too simplified,which affects the movement performance of the robot,a new force model of driving leg on water surface is established by considering the water surface deformation and additional mass.Computational fluid dynamics(CFD)simulation is used to analyze the influence of the rowing speed and entry angle of driving legs on driving force.Then the established force model is modified and optimized.On this basis,the hydrodynamic experiments of a water-entry driving leg are carried out.The results verify the accuracy of the force model of the driving leg and the CFD simulation method.It provides a basis for the design and performance optimization of jumping robots on water surface.Then a new jumping robot on water surface is proposed.the overall structure of the robot is designed.Based on the established force models of the water pressure driven robot,the dynamic simulation of the robot jumping on water surface was carried out.The parameters of the robot,including the support system and rowing range of driving legs are optimized.Then the robot prototype is assembled,the jumping experiments are carried out.By comparing with other water pressuredominated jumping robots on water surface,the performance of the robot is analyzed and evaluated.