Three-degree-of-freedom positioning control of magnetically levitated permanent magnet planar motor using active disturbance rejection control scheme

Xinhua Zhang,Qing Zhu,Zebin Yang,Xiaodong Sun,Yukun Sun

doi:10.1177/1687814017700088

Abstract

Magnetically levitated permanent magnet planar motor is a new-generation motion device in modern precision industry, and the design of advanced motion controller has always been a main concern in the research and development of magnetically levitated permanent magnet planar motor. Due to the decrease in electromagnetic force caused by the deflection of the mover or the sharp decrease in magnetic flux density with height, it is very difficult to realize accurate positioning control of 3 degrees of freedom. In this article, an active disturbance rejection control scheme is adopted. The extended state observer is used to estimate the comprehensive disturbance and motion state in real time. Then, according to the value estimated by the extended state observer, the active disturbance rejection control motion controller can compensate the electromagnetic force in time to achieve good anti-jamming performance. Simulation and experimental results demonstrate that the adopted active disturbance rejection control scheme has good dynamic performance and uncertain disturbance robustness.

Highlights

The permanent magnet planar (PMP) motor has become one of the best performing mechanisms of the new-generation lithography machine due to its structural diversity, larger thrust density, favorable lowspeed stability, and other excellent properties.[1]
For the magnetically levitated permanent magnet planar (MLPMP) motor, if the uncertain disturbance caused by the mover deflecting through small angles is considered, and based on equations (3) and (7), the mechanical thrust balance equation describing the x-axial horizontal motion can be expressed as follows ðm + DmÞS€x + hx = fx fx = KxyeÀptznc Imx cos (Bu) + d ð8Þ
In order to verify the effectiveness of active disturbance rejection control (ADRC), an ADRC system for MLPMP motor is built and simulated in the MATLAB/Simulink environment

Summary

Introduction

The permanent magnet planar (PMP) motor has become one of the best performing mechanisms of the new-generation lithography machine due to its structural diversity, larger thrust density, favorable lowspeed stability, and other excellent properties.[1] Traditional two-dimensional (2D) plane positioning device is generally composed of two sets of linear motion conversion structures and driven by two rotating electric motors. It is difficult to achieve higher level positioning accuracy owing to the linear motion conversion mechanism of friction, backlash, and deformation. Air bearing positioning platform can eliminate the friction, its structure is complex and the support stiffness is small, which result in lower bearing capacity and poor ability to resist shock.

Methods

Results

Conclusion