A Design Of The Bionic Robot Fish Actuated By The Giant Magnetostrictive Material And Numerical Simulation Of Its Swimming Control

With the development of science and technology, more and more robots are used into industry, agriculture, military, medicine and domestic life. Various robots develop rapidly where bionic robot fish is one of their types. The miniaturization of the bionic robot fish is a kind of development trend, therefore, the power system and control system of the robot have faced higher demands. The design of fish-like micro robots with the giant magnetostrictive material, without carrying the power system, can realize the control of the robot fish swimming through the change of the external magnetic field only. Thus, fish-like micro robots of giant magnetostrictive material have a good development prospect. So it is of great scientific significance and engineering application value to study the design and control of the bionic giant magnetostrictive fishes.The alloy sheet is simulated as the framework of the fishtail of fish-like robot, the giant magnetostrictive material, which is attached the sheet, as the muscle of the fish and the external magnetic field as the nerve to control the swing of the fishtail in this paper. Thus a biomimetic robotic fish model with the giant magnetostrictive material is presented. The robot fish swimming can be controlled aid the adjustment of the external magnetic field, meanwhile, and the problem is studied by the use of numerical simulation method. Main research results include:fundamental control equations and initial and boundary conditions are established thus forming a closed fundamental problem, in which the viscous of liquid is considered, the added inertia mass caused by fluid is analysed and the vortex counterforce caused by fin swing is discussed. Based on the model of biomimetic robot fish, an analytical solution method, a semi analytical method and a numerical calculation method are obtained by analyzing and solving the governing equations. According to the nervous system of real fishes to control muscle fiber from data and signal of electromyogram in experiments, Several typical functions of the external magnetic field are given by simulation of muscle contraction of real fishes for controlling the robotic fish. The numerical simulation results show that this form of external magnetic field can improve the swimming speed and stability of the robot fish, and the rationality is shown also for the real fish nervous system controlling muscle contraction. This conclusion provides a basis for bionic design of robot fish. On the basis of the above, the paper presents an idea of variable frequency of the external magnetic field to control starting and cruising of the fish. In robotic fish starting and cruising stages, the different intensity and frequency of the external magnetic field are controlled, starting and cruising velocities are improved greatly including the frequency of the external magnetic field varies with time in the robotic fish starting stage. The results show that this method is feasible and effective, and it is proved that the electromyogram rule of muscle contraction pattern is reasonable. Based on of the results, the method of parameter optimization is applied to optimize distributions of skeleton and muscle of the robotic fish body and distributional curves of the thicknesses of skeleton and muscle are obtained for quick starting and the swimming modes, which the thickness of alloy sheet, the thickness of giant magnetostrictive material and the frequency of external magnetic field are determined for controlling optimal swimming of the robotic fish. The curves of thickness distribution are agreement with nature fish body and swing mode of caudal fin for fish swimming, so as to reveal the mechanism of the physical characteristics of the fish in nature. The research results of this paper not only present a reliable basis for the design of others robot fishes, but also provide a new way for swimming control of robot fish.