Research On Structure Design Of A Reluctance Spherical Motor

Spherical motor(SM)is a new and special type of multi-degree-of-freedom(multi-DOF)device,which can realize multi-dimensional motion in space.SM can form a multi-DOF transmission system,which not only has the structure advantages of small size and light weight,but also has the performance advantages of fast response and high system accuracy.Therefore,spherical motors have great application potential in fields such as robots with drive systems.However,the overall structure of spherical motors is spherical,and most of them have the characteristics of strong coupling and high nonlinearity.Thus,there are some problems such as high manufacturing process technology,difficult driving control and position detection.Thus,various types of spherical motors are not perfect enough at present,they are still in the theoretical research stage,and more in-depth research is needed.Based on the analysis of the development and research status of spherical motors,a design scheme of 3-DOF reluctance SM based on the principle of minimum reluctance is proposed in this thesis,and the optimization of its structure parameters is studied.The main research work of this thesis is as follows:(1)Firstly,the basic structure of the proposed 3-DOF reluctance SM is introduced in detail,and the basic p rinciple of the 3-DOF spinning and tilting motion of the SM is expounded respectively in this thesis.According to the electromagnetic law and the principle of energy conversion,the basic mathematical model of SM is established.(2)The three-dimensional finite element(FE)models of spinning and tilting of the SM are established respectively.The magnetic field distribution and static torque characteristics of spinning and tilting of the motor are obtained by using 3D finite element method(FEM).The analysis results show that the motor has a holding torque in spinning and tilting motion,which proves the feasibility of the proposed SM.(3)The variation rules of the torque of spherical motors with the main structural parameters are analyzed in systematically.And the curves of spinning and tilting statictorque of the spherical motor with the rotor tooth width,the rotor tooth thickness,the stator tooth width,the stator tooth thickness and the air gap are obtained respectively.Then the range of values for each parameter is determined,which the static torque of spinning and tilting are relatively largest.(4)Based on the Taguchi method,the structure parameters of the SM are synergistically optimized.Taking the spinning torque and the tilting torque as optimization targets and the structural parameters as optimization factors,an orthogonal table of optimization design experiment of the SM is established.Each experiment in the orthogonal table is calculated by FEM,and the optimal scheme of parameters is obtained according to the results of statistical analysis.Finally,the FE simulation results of the SM before and after optimization by Taguchi method are compared,and the validity of Taguchi method for the optimization of the SM in this thesis is verified.