應用於兩軸致動機構之光學影像穩定器的動態建模與驅動系統設計

Abstract

本論文提出一應用於手機相機之光學影像穩定器(OIS)的動態建模與驅動系統設計，此防手震技術將改善手機相機在拍攝時，因手部晃動所造成影像模糊的問題，使拍攝時得到更清晰的影像。本設計使用兩軸旋轉機構來進行鏡頭內光學模組及感光元件之位置補償，此機構由音圈馬達(VCM)致動器來控制旋轉角度，達到拍照時的防手震效果。整個研究可以分成三大部份：防手震致動器機構設計；動態數學模型建立與動態方程式推導；控制器設計。第一部份使用SolidWorks軟體進行機構設計，建立兩軸(pitch軸/yaw軸)致動機構之光學影像穩定器，其中包含相機鏡頭模組懸吊裝置、磁鐵與線圈構成的微小音圈馬達致動器等，再透過機構最佳化設計磁路。第二部份之兩軸旋轉致動系統之動態分析與動態方程式(EOM)推導，根據Lagrange所提出的方法，導出光學影像穩定器受震動時的動能與補償電流產生的電磁力矩之關係，藉此方程式設計對應的控制器。完成前述工作之後，第三部份比例積分微分控制理論的應用與控制器的建構，經由模擬與實驗來驗證控制器之功效後，再經由實際的電路來建立系統。此光學影像穩定器之控制雙軸傾斜範圍±1°，控制安定時間為0.5秒，輸出峰值電流為40mA。

This study proposes design, dynamic modeling and drive system of a two degree-of-freedom (DOF) rotational optical image stabilizer (OIS) in the camera embedded in the mobile devices. This OIS differs from the previous designs since it stabilizes the angular position between lens holder and image sensor by a two-DOF rotational mechanism that is actuated by voice coil motors (VCM). It can provide a solution for a fuzzy image due to the hand-shaking. Such category of technology will enable cameras-phones images reaching more clear effect. The work can be divided into three main parts: designs of mechanism, establishments of the dynamic model and equation of motions (EOM) of a rotational structure, and realizations of a proportional–integral–derivative (PID) controller with high-precision. The first part focuses on the rotational movements (in x/y axes) by adopting optimized yokes and magnets to provide optimal magnetic fields for actuation. In the second part, the dynamic of the rotational OIS system has been analyzed and the EOM has been derived. Based on the Lagrange’s method, the motions of the OIS have been modeled through considering kinetic energy and electromagnetic torques. In the last part, the theory of PID control is applied, and the associated simulations are conducted. Based on the simulation results, the PID controller is forged with the assistances from MATLAB pre-simulation and tested by a microprocessor module. The controller would be built up to match the design which contains the drive system for anti-shake mechanism. After a series of experiments and verifications, the prototype of the novel OIS is finally accomplished with satisfactory performance of vibration reduction. The designed OIS module can reach a control tilting range of ±1 degree in the required 0.5 second. As the maximum output current is 40 mA.