Analysis and Control on a Specific Electromagnetic Micromirror

Wanyan Sun,Ruili Dong,Yonghong Tan,Wenjiang Shen

doi:10.1155/2020/4612376

Abstract

In this paper, 10 resonant modes were divided based on the structure of a specific two-dimensional electromagnetic micromirror from Professor Shen’s team and Finite Element Method (FEM), and using as many as 10 resonant modes to do such analysis was the first time according to the best of our knowledge. The results showed that the slow axis can participate in several resonant motions under the signals of resonant frequencies. In particular, participating in Mode 1 for slow-scan axis was the key reason to the instability of Vertical Refreshing Scanning (VRS) in raster scanning. In addition, a piecewise PID control based on filters design for this electromagnetic micromirror was proposed to suppress the unexpected resonant oscillation and to improve the angular positioning accuracy in slow-scan axis control. Finally, the proposed method was applied to electromagnetic micromirror stages, and the experimental results showed that the proposed approach was reliable.

Highlights

Electrostatic micromirror is well developed for use by omas Bifano and Texas Instrument Inc. omas Bifano reported an array of electrostatic actuator shaping the mirror [4], while Texas Instrument Inc. was dedicated to developing an array of aluminum micrometer-sized mirrors, in an orthogonal layout for full HD projector and display [13]
Ji et al [16] proposed a two-dimensional electromagnetic micromirror using single turn coil and radial magnetic field from concentric magnet assembly in 2007, which was the first paper reported on this topic
Combined with the Finite Element Method (FEM) (Figure 2), in Vertical Refreshing Scanning (VRS) control, when the slow-scan axis operates in a noisy environment with resonant frequencies shown in Table 2, ten resonant motions are inspired to destroy raster scanning, which means that the key to stable control of electromagnetic micromirror is the stability of Mirror material Si

Summary

Introduction

Micromirror is a MEMS (Micro-Electro-Mechanical System) device, which is widely used in optical communication, head-worn display, LIDAR (Lighting Detection and Ranging), projector, and medical imaging detection [1,2,3,4,5,6,7,8,9]. ere are four main types of micromirrors in driving manners, including in electrostatic micromirror [3, 10], piezoelectric micromirror [11], electro-thermal micromirror [12], and electromagnetic micromirror [5, 6]. Design and fabrication of this electromagnetic micromirror and 6 vibration modes were focused on in their paper, and the control was located in open loop control. Chen et al [5] reported a two-dimensional scanning micromirror electromagnetically driven for slow-scan axis and harmonically driven for the fast-scan axis with larger mechanical angles up to ±7.5∘ and ±12.5∘, respectively. Steve et al [17] focused on Newton’s method to determine the harmonic coefficients of the two-dimensional electromagnetic micromirror, but controlling the mirror deflection to correctly produce the desired angular motion presented a significant engineering challenge. E results showed that the slow axis participated in several resonant motions under the signals of resonant frequencies, which were the key reasons for the instability in slow-scan axis control of this two-dimensional electromagnetic micromirror. The proposed methods were applied to an electromagnetic micromirror platform to determine their reliability

Modal Analysis of Electromagnetic Micromirror

Filters Design

Piecewise PID Control and Experiments

Conclusions