聲學阻抗匹配之前饋和回饋的主動式噪音控制器設計

Abstract

本論文是針對主動式噪音控制提出各種不同的方法，並且把他應用於 管路消音，以及 消音耳機方面。本論文大致可分為三個部分：第一部分 是介紹主動式噪音控制 (ANC) 的消音原理及其發展過程。 第二部分則是使用阻抗匹配的前饋控制，首先先簡單的介紹聲學阻抗的觀 念，再把聲 學阻抗和電學阻抗結合起來，進而使用簡單的電路學觀念來 達到消音效果。最後使用適應 方法求得控制器加上以喇叭模表面取得前 饋訊號，並把他應用於耳機和管路的消音。 第三部分則是回饋 控制法則，控制器的設計亦嘗試著使用以不同的方法：1.相位補償 電路 。2.最佳化2_norm設計。3.最佳化H_infinite norm設計。4.改變系統阻 尼比設計法。並且比較他們的消音效果。此外，並針對受控體和控制器設 計間的關係加以討論如何來改 進消音的方法。 In this thesis,many different methods of active noise control are proposed and experimented for active noise cancellation in duct and earphone. In general ,this thesis can be divided into three parts : First part of the thesis is a brief introduction of ANC principles and its historical review. The second part is the feedforward control using acoustic impedance matching. First, acoustic impedance concept is introduced.Then,we combine the acoustic impedance and electric impedance together and use the simple electric_circuit concept to obtain the goal of noise cancellation.Finally,we use adaptive method to find the controller and obtain the feedforward signal by using surface of loudspeaker.Then,we apply for noice cancellation in duct and earphone. The third part is the feedback control of ANC.We try to use different methods to find the controller.These methods are: 1.Phase compensation method. 2.Optimal 2_norm design. 3.Optimal H_infinite norm design. 4. Change damping ratio of plant. Their results of noise cancellation are compared.Moreover, according to the relation between plant and designing controller,how to improve the noise cancellation methods are discussed.