Design And Experimental Study On The Oscillating Propulsion Device Based On8-8Parallel Mechanism

The high speed and high mobility of fish has attracted wide attention ofnumerous scholars, bionic propulsion device has become a research focus in thefield of bionic research. Bionic propulsion research has important applicationvalue in ocean exploration, marine salvage, and military field. The bionicoscillating propulsion device that imitates the tuna fish becomes the key researchcontent because of its advance speed, high efficiency and strong maneuverability.It could be used in the underwater environment with wide-range for a long time.To imitate the tuna fish, a new bionic oscillating propulsion device based on8-8redundant parallel mechanism is proposed in this paper.The physiology characteristics of tuna fish are analyzed first in this article,and it obtains the design requirements of the bionic oscillating propulsion device.Appearance, structure and characteristics must match the fishs’. Choose8-8redundant parallel mechanism as the foundation for the structure design, itdeduces the conditions of structural parameters design through the kinematicsanalysis of8-8parallel mechanism and decoupling calculation, and sums up adesign method.According to the locomotion mechanism of fish, it puts forward a theory thatthe bionic oscillating propulsion device is drived passively in this paper. Based onthe kinematics and internal dynamics of fish, the amplitude envelope of the bodylateral deflection and Lighthill’s slender body theory, it deduces a new method todesign the stiffness of bionic oscillating propulsion device, which shows therelationship between the driving frequency and stiffness.Furthermore, a SimMechanics simulation model of bionic oscillatingpropulsion device is established based on the analysis of fish swimming. Ensuringstiffness design frequency is invariant when changing the driving frequency, itconclude that the bionic oscillating propulsion’s swimming performance is bestwhen the driving frequency and stiffness design frequency are similar. When thestiffness design frequency and the driving frequency of bionic oscillatingpropulsion device are always consistent, the simulation results show that theswimming speed is approximate linearly direct proportion to driving frequency.Finally, the paper made prototype of bionic oscillating propulsion devicebased on8-8redundant parallel mechanism. The stiffness measurement andswimming performance experiments confirm that, the bionic oscillating propulsiondevice has the best swimming performance when the driving frequency is close to the natural frequency.