Research On Wave Motion Of Flexible Fin Of Underwater Robot

The underwater robot driven by propeller has some problems such as loud noise and serious cavitation,and the marine fish swimming on the center fin / counter fin has strong maneuverability and anti-interference.In this paper,the main structure design,fin surface fluctuation movement and prototype test of bionic fish swimming on the center fin / counter fin are studied.In this paper,two kinds of motion modes of underwater robot's fin surface sinusoidal wave and fin surface symmetrical wave are studied,and the shape and size of the underwater robot body are designed.The flexible fin transmission mechanism based on the movement principle of crank block mechanism is designed.The structure form of crankshaft is the key part in the transmission mechanism.A kinematic coordinate system was established for the designed flexible fin transmission mechanism,and the kinematic coordinate function of each hinged point was studied.Secondly,CAE simulation method was used to study the transmission mechanism of the flexible fin.The motion trajectory of the fin end and the function relationship between the driving parameters of the crankshaft and the output parameters of the fin were obtained.The swing velocity of the fin showed a sine trend with time.The rigid-flexible coupling simulation was carried out for the motion of the fin and the fin,and the deformation of the flexible fin was studied when the fin swayed sinusoidally and symmetrically.The motion equation of the wave trajectory of the outer edge of the fin was established,and it was verified by simulation.Again,the hydrodynamic performance of fins is carried out.The single fin fluttering model is solved by CFD calculation fluid method.The fixed fluctuation simulation of fins in the water surface is obtained.The region corresponds to the high / flow rate region of the lower surface,and the fin sine fluctuation forms a vortex cycle at the end,and the fin face-to-artifact does not appear.The pressure difference between the upper and lower surfaces of the fin is simulated and studied.The high pressure area of both wave modes occurs at the tip of the fin,where the sinusoidal wave occurs when the tip of the fin moves toward the end of the fin,while the symmetrical wave occurs only at the tip and the end.Different wave amplitudes and periods are used as input parameters to simulate the wave propulsion on the fin surface,and the relationship between the wave force and the drag force on the fin surface is calculated.The results show that the drag and the drag force on the fin surface increase with the increase of the wave amplitude and the decrease of the wave period.Finally,a prototype of the flexible fin underwater robot is made,and the control system is developed based on the Arduino control board.The simulation results of sinusoidal and symmetrical fixed wave on the fin surface are verified by the undulating ink experiments with a prototype.The sinusoidal wave propulsion experiment and the symmetrical wave submersible diving experiment are carried out to prove that the fin surface has a certain propulsion ability in sinusoidal wave,and the fin surface has a certain diving ability in symmetrical wave.The cooperative motion of the two fins of an underwater vehicle is studied.When the two fins undulate in the opposite direction,the underwater turning motion can be realized and the turning radius is small.