Research On Control Method Of Multidegree-of-freedom Positioning Platform Driven By Plane Motor

At present,a multi-degree of freedom of precision positioning platform has a very urgent demand in many industries,such as integrated circuit manufacturing,micro-electromechanical systems manufacturing.It is imminent for the development of a precision positioning platform with multiple degrees of freedom,high positioning accuracy,simple structure and large thrust.In this paper,the control method,the suppression and optimization of thrust fluctuation caused by motions,the thermal characteristics of multi-degree-of-freedom precision positioning platform driven by improved Y-shaped planar motor were analyzed and designed.Firstly,the coupling mechanism of Y-shaped planar motor was analyzed,and it was found that the control model of the system has strong coupling characteristics,and then the decoupling algorithm was designed according to its coupling characteristic.The algorithm mainly applies the linearization idea.The motion of each degree of freedom is controlled by assuming a set of control currents which are proportional to the force vectors of the respective degrees of freedom.That makes every degree of freedom motion control model independent.In addition,the reason for the thrust fluctuation of improved Y-shaped plane motor was analyzed.This paper compensated and optimized the thrust fluctuation which is caused by the rotation of the moving platform and back electromotive force in the coil winding.It reduces the thrust fluctuation of the plane motor and improves the control precison.Secondly,in this paper,a water jacket cooling structure was designed according to the structural features of the improved Y-shaped planar motor.And the thickness of the serpentine channel of cooling structure was designed as 4mm by simulation and calculation.At this time,the convective heat dissipation coefficient was 5.6×103/(m2·?).Then the temperature field of the driving unit was simulated by this parameter.When the currents in two coil windings of drive unit were 2A,the maximum temperature of the drive unit reached 77 ? in the absence of forced water cooling condition.The maximum temperature of the drive unit was reduced to 30 ? under the same conditions after the forced water cooling was added.The thrust fluctuation of the driving unit decreased from-2.16%to-0.3%after the forced water cooling was added.In addition,the simulation results were verified by experiments of the drive unit temperature rise.Finally,the experimental platform was set up and the motion index of the positioning platform designed by this paper was tested.The experiment shows that the stroke of the positioning platform is 7mm,the resolution is 7?m,the maximum no-load acceleration is not less than 0.34m/s2,the maximum acceleration is less than 0.27m/s2 and the thrust is not less than 1.31N when the load is 1kg in Y direction.The stroke of the positioning platform is 6.8mm,the resolution is 7?m,the maximum no-load acceleration is not less than 0.42m/s2,the maximum acceleration is less than 0.33m/s2 and the thrust is not less than 1.54N when the load is lkg in X direction.The rotation range of the Rz direction is ±0.6°,the rotation resolution is 11.5 ".In addition,the experiment was also carried out for the coupling of the degrees of freedom motion.At last,the circular trajectory motion experiment was carried out for the positioning and following characteristics of the positioning platform on two-dimensional plane.