Research On Driving And Control Method Of Three Dof Permanent Magnet Planar Motor

The planar motor designed in this paper is a new type of multi-degree-of-freedom motion mechanism directly driven by Lorentz force.It has the advantages of simple structure,flexible motion,good dynamic characteristics,high positioning accuracy and low friction loss.This paper is oriented to the field of high-precision manufacturing and measurement.Taking permanent magnet planar motors as the research object,a permanent magnet planar motor that can be accurately positioned in the three degrees of freedom of x,y and Rz in the horizontal plane is designed.A magnetic field modeling method based on the combination of analytical model and finite element is proposed.The force model of the planar motor drive unit under the action of the Halbach array magnetic field is established,and the driving force orthogonal solution is carried out for the two-phase coil winding structure designed in this paper.Coupled,a reasonable current distribution method is given.Combined with the output structure of the drive unit,the horizontal motion and thrust coupling modes of the planar motor are studied,the control system of each degree of control is linearized,and the sources of different disturbances of the planar motor are analyzed and the compensation method is given.The planar motor is completed.The controller design of the motor positioning system improves the dynamic and static performance of the system,and the simulation analysis is carried out.Finally,the entire permanent magnet planar motor system is experimentally verified.First,combined with the permanent magnet planar motor model structure designed in this paper,the overall structure of the planar motor is introduced,and the working principle of the drive unit is explained.Studying the error between the magnetic induction intensity harmonic analysis model of the one-dimensional Halbach array and its fundamental wave approximation model,it is found that although the fundamental wave approximation method can better simplify the complexity of the model,the model error caused by the fundamental wave approximation affects the system The influence of,cannot be ignored.On the basis of the harmonic analysis model,the finite element simulation analysis is used to add a proportional coefficient correction function to the fundamental wave approximate model,and a magnetic induction model that describes different air gap heights more accurately is established.The force model and current expression of the drive unit under the semi-analytical magnetic field model are established,and the influence mechanism of the main structural parameters of the coil winding and the equivalent working height on the coil thrust coefficient is studied.The thrust coupling structure of the two-phase coils of the drive unit is analyzed,and the current decoupling distribution method of the coil windings is given.Combined with the distribution structure of the permanent magnet array and the coil windings,the influence of the back-EMF generated during the motion of the planar motor on the model is analyzed,and the back-EMF compensation method is proposed.Secondly,the horizontal three-degree-of-freedom dynamics model of the planar motor is established,combined with the output structure of the drive unit,the coupling relationship between the input current of the planar motor system and the motion output of each degree is studied,and the rotation of the mover yaw angle suppression is analyzed.Moment constraint conditions,using linearization ideas,the input and output decoupling model of the control system is established,and the output distribution mode of the drive unit for motion control with different degrees of freedom is given.According to the dynamic differential equation of the decoupled linear system model,the control system model of the plane motor is established.The PD controller is designed for the undamped second-order system of the plane motor,and the dynamic and static characteristics of the closed-loop system are analyzed in the time domain.The influence relationship between the parameters of the planar motor system controller and the system index is given.The source of disturbance force of the planar motor system is analyzed,and a disturbance compensator is designed to compensate for external disturbance.Finally,a planar motor experiment platform was built to verify the positioning function of the planar motor system.The experimental results show that the resolution of the planar motor in the x direction is 3μm,the positioning noise is about ±1μm,and the repeated positioning error is 1.13μm;the resolution in the y direction is 3μm,the positioning noise is about ±1.75μm,and the repeated positioning error is 1.45μm.