Design Of Tracking Control Systems With Zero Steady-state Errors For 3-DOF Magnetically Levitated Planar Motors

Magnetically levitated planar motor is an advanced driving device as it can make the driven motion to achieve better dynamic performances and higher motion accuracy.It has prosperous applications to drive advanced manufacturing equipment such as integrated circuit manufacturing and micro-nano manufacturing etc.This thesis focuses on the study of trajectory tracking control problem.It aims at designing the state feedback and the output feedback closed-loop control systems which are based on the internal mode principle of three degrees-of-freedom(DOF)magnetically levitated planar motor with moving coils.In this thesis,established the dynamic model of a magnetically levitated planar motor with moving coils.Analyzed the dynamics characteristics of the selected threeDOF motion,vertical levitation motion,horizontal linear motion,and plane rotation about vertical axis,and the transfer function matrix model and state space model are derived.This paper has also established the common unstable internal model of the reference input and the disturbance,the closed-loop pole points of three-DOF motion control system are placed according to the dynamic performance requirements,and the state feedback closed-loop control system that can realize zero-steady-error trajectory track is designed.Furthermore,the dynamic performances are improved by placing PD controller before the internal compensator.Considering the physical realization of the output feedback,the paper also uses the transfer function matrix fractional description method to transform the new non-cyclic controlled system into the cyclic transfer function matrix fraction which based on the internal mode principle,and the output feedback closed-loop control system that can realizes zero-steady-error trajectory track is designed.This paper has lots of simulation about the two zero-steady-error trajectory tracking closed-loop control systems.Simulating results indicate that while the unstable internal models of the disturbances are embed in the control systems,both of the closed loop control systems have good dynamic performance,and accurate trajectory tracking performance can be achieved for both sinusoidal reference and square wave reference inputs.