Study On The Oscillating Propulsion Technology Of Cartilaginous Fish

With the rapid development of underwater equipment,the traditional underwater propulsion system,represented by propeller,can not meet the needs of underwater equipment because of its high energy consumption,heavy weight,large volume,noise,poor mobility and other defects.The development of new underwater propulsion equipment is imminent.Fish has attracted more and more researchers' attention because of its excellent underwater swimming characteristics.In this paper,a new type of bionic fish structure is designed,and the research and experiment of improving the swimming speed of the bionic fish are carried out by using the bionic fish prototype.The bionic fish designed in this paper takes tuna as the bionic object.Through the research on the physiological structure characteristics and swimming mode of tuna,combined with the problems existing in the traditional underwater propulsion system,a new multi joint bionic fish structure is developed.The main driving device of the structure is rope,which simplifies the driving mechanism,reduces the energy consumption and improves the control sensitivity of the bionic fish.Using the underwater driving mode of muscle like driving,the rigidity,frequency and amplitude of the bionic fish tail are adjustable.In order to detect the fitting degree between the movement track of bionic fish tail and that of real fish tail,the kinematics model of bionic fish was built,and the kinematic relationship between the driving actuator and bionic fish tail was established,and the movement track of bionic fish tail was compared with the wave curve of fish body.Through the dynamic calculation and Simulation of the bionic fish tail,the natural frequencies and vibration modes of the bionic fish tail under different frequencies are solved.The underwater motion simulation of bionic fish can provide guidance for the real experiment.In this paper,the underwater virtual prototype of the bionic fish is established by the hydrodynamic analysis of the bionic fish.In this paper,the virtual prototype is used to simulate the swing characteristics of the bionic fish and the tail swing frequency,the tail swing amplitude,the maximum impact angle of the tail fin which affect the swimming speed of the bionic fish.The control variable experiment of the bionic fish prototype is carried out,and the simulation results of the virtual prototype are compared.The relationship between the swimming speed of the bionic fish and the tail swing frequency,the tail swing amplitude,the maximum impact angle of the tail fin is obtained.The reason of slow swimming speed of the bionic fish developed in this paper is analyzed,and the improvement measures to improve the swimming performance of the bionic fish are put forward.