創新雙軸旋轉機構之光學影像穩定器的動態建模與控制器設計

Abstract

本論文提出一用於手機相機之新型光學影像穩定器(OIS)，整個研究逐步完成機構設計、磁場最佳化、動態分析與控制器的實現。過去的光學影像穩定器多採用二維平面位移的機構，然而此種設計之補償效果較受限制，本設計使用雙軸旋轉機構來進行補償，此機構由音圈馬達(VCM)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：（1）防手震機構設計與基因演算法之磁路最佳化；（2）系統動態模型之建立與動態方程式之推導；（3）順滑模態(SMC)控制器的設計與實作。第一部份使用CAD軟體進行機構設計，建立此光學影橡穩定器的雙軸(pitch軸與yaw軸)旋轉機構，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等，並為了縮小體積而拿掉了導磁軛片(yoke)，再透過基因演算法最佳化設計磁路，得到穩定而合適的磁場。第二部份致力於此雙軸旋轉系統的動態分析與動態方程式( EOM)推導，根據Lagrange所提出的方法，整個光學影像穩定器的動態方程式可經由推導其受震動時的動能與補償電流產生的電磁力矩之關係來導出，藉此方程式可設計對應的控制器。完成了前述工作之後，第三部份著重於順滑模態控制理論的應用與控制器的建構，首先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，並完成實品的防手震功能測試。

This study proposes design, optimization and validation of a new two degree-of-freedom (DOF) rotational optical image stabilizer (OIS) that is suitable for installing into a mobile-phone-camera. This OIS differs from the previous designs since it stabilizes the lens holder by two-DOF translational mechanisms that are actuated by voice coil motors (VCM). The work can be divided into three main parts: (1) designs of mechanism and genetic algorithm (GA) optimization of magnetic field, (2) establishments of the dynamic model and equation of motions (EOM) of a dual-axis rotational structure, and (3) realizations of a sliding mode control (SMC) controller with fine performance. The first part focuses on the translational movements (in x and y axes) by adopting optimized yokes and magnets to provide optimal magnetic fields for actuation. A novel yoke-less, small-sized OIS actuator, is designed in this study to own yaw and pitch rotational movements, the axes of which are in the nature of hand-shaking, and thus brings superiority of compensating performance over translational design. In the second part, the dynamic of the dual-axis 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 sliding mode control (SMC) is applied, and the associated simulations are conducted. Based on the simulation results, the SMC controller is forged with the assistances from MATLAB pre-simulation and tested by a microprocessor module. After a series of experiments and verifications, the prototype of the novel OIS is finally accomplished with satisfactory performance of vibration reduction.