Research On Paddling Forward Mechanism Of Diving Beetle For The Issue Of Micro-uuv's Sneak Underwater

Micro-UUV is not only play an important role in military field,such as maritime reconnaissance,communication relay,intelligence gathering,and diving concealment,but also plays important roles in civil areas such as marine disaster rescue,environmental information detection,and marine geography research.The underwater propulsion mode of underwater vehicle has great significance in their research.Bionic propulsion has been a hot research topic in academic circles in recent years.Compared with traditional propulsion methods,bionic propulsion has the advantages of high propulsion efficiency,flexible movement,low noise,and good concealment.Diving beetles have the ability to move in three states: water,land,and air.There efficient underwater propulsion performance and ability to turn and retreat in situ have aroused the interest of scholars.They are excellent biological models for underwater vehicle research.The adult diving beetle is the research object of this article.We analyzed their morphological and kinematic characteristics,and carried out resistance test tests on the imitated hind plantar swimming hair samples and comparative samples,and combined with the flow simulation of the prototype model to explain the highly efficient paddling forward mechanism of diving beetle.The details are as follows:We observed and analyzed the living habits and movement characteristics of diving beetles,and analyzed the structural characteristics of each foot of diving beetles using a stereo microscope.It was found that the length of the swimming leg that provided the main power for the exercise was about 25 mm,and the tarsi had paddle-shaped swimming hairs,with a length of about 5mm and a diameter between 5 ?m and 25 ?m.We observed the microscopic morphology of the surface of the swimming hair with a super depth of field microscope,an atomic force microscope,and a scanning electron microscope,and found that the surface was uneven with microporous structures.Infrared spectroscopy tests of swimming hairs confirmed that the composition had hydrophobic groups methyl and amino groups,and the measured surface contact angle of the swimming hairs was 130o,indicating that the surface had hydrophobic properties.The experimental platform was set up to obtain the video of the diving beetle's free movement in a transparent fish tank.The change law of the joint angle over time was analyzed.The kinematic model of the diving beetle's hind leg was established by the D-H parameter method,and the trajectory of the hind leg movement was obtained.It is found that the obtained trajectory has a high degree of agreement with the actual trajectory of the diving beetle.Bionic swimming hair samples and seamless plate contrast samples were processed using fiber laser marking machines.The resistance test device was set up for experiments.The test results show that the resistance to the bionic swimming hair sample increases as the swimming hair gap decreases.When the gap size reaches the true gap size of the diving beetle,its resistance will be greater than the seamless board of equal area.The swimming hair structure of the diving beetle will increase the value of the propulsive force during its movement.Change the angle of attack of the sample and repeat the above experiment.It is found that the resistance value of the sample increases as the angle of attack increases.During the power stroke,the diving beetle's legs are rotated by 90o to advance at the maximum angle of attack to obtain maximum propulsion.The OpenFOAM software based on the finite volume method was used to analyze the stress of the bionic swimming hair model and the seamless plate contrast model.It is found that the resistance value of the bionic swimming hair model is greater than that of the equal area seamless plate model at the same speed.Viscous resistance accounts for about 30% of the resistance to the bionic swimming hair model,and increases as the gap size decreases.