主動式噪音消除耳機系統之回授控制器設計與實現

Abstract

本論文以回授控制技術應用於主動式消音耳機之設計，再由電路將主 動式消音耳機加以實現並已經由實驗證明其在低頻帶的噪音消除能力。本 論文大致分為三部分： 第一部份（第一、二章）是介紹主動是噪 音控制的消音原理及其發展歷史，並將消音耳機系統的設計架構及限制加 以說明。 第二部分是以 麥克風回授製作消音耳機，在控制器的設計上分別以不同的方式設計控制 器包括：1、改變系統阻尼比設計。2、以模式匹配改善受控體響應再設計 控制器。3、 最佳化理論設計控制器。並將控制器加以實現比較不同控制 方法下的消音效果。 第三部份是將原先的麥克風回授外加入喇叭膜 速度回授，希望藉由控制器設計自由度的增加，而改善系統在非常低頻時 的表現。而速度回授觀測器是由喇叭電路、磁場及機械部分的關係所推導 出來。但是最後加入喇叭膜速度回授等效於一個相位領先的補償器。 In this thesis, we apply feedback control techniques to design an active noise reduction headset. The controllers are implemented by analog electrical circuits and experiments show significant reduction of noise level at low frequency range. This thesis is divided into three parts: in the first part, a brief introduction of active noise control techniques and its historical. Further, the control framework and design limitations are presented . The second part describes several controller design methods. These methods are: 1. changing damping ratio of the plant. 2. Using model matching methods to improve plant frequency response before designing controllers. 3. Designing controllers by optimization. Then, these controllers are implemented and results of noise reduction are compared . In the third part, a speaker cone velocity feedback is added into the controlloop. The motivation is to increase the degree of freedom of controller design and improve performance in very low frequency range. The velocity is observed by using electro- magnetic-mechanical relationship of a speaker. It turns out that the added controller is equivalent to a lead compensator.