管路主動噪音控制系統之DSP控制器實現

Abstract

本研究探討在管路系統之寬頻主動噪音控制的問題中，各種控制法則之實現，以及使用合成參考輸入之最小均方法（least-mean-square, LMS）於窄頻之主動噪音控制問題。在寬頻的問題上，因為聲場回饋的關係，我們考慮空間前饋的結構並使用後向的控制喇叭以減低聲場回饋的效應，而我們採用的控制法則包括：勞爾（Roure）控制法則、最小均方法的相關法則、適應性前饋控制法則、以及由Q參數法導出之最佳化控制法則。而在窄頻的問題上，我們考慮兩種情況，第一種情況是噪音源之操作頻率為單頻的噪音，第二種情況則探討噪音源之操作頻率會在一頻帶產生變動。以上所提及的控制方法，均將於一數位訊號處理控制卡上加以實現，透過對此管路系統的詳細設計、分析、與實驗，我們將證明這些方法均有控制效果。

This research proposes several approaches for the broadband active noise control (ANC) problem of duct systems and the least-mean-square (LMS) algorithm with synthesized reference signal is implemented in the narrowband ANC. In the broadband attenuation, the spatially feed-forward structure is considered because of the acoustic feedback problem and the backward control loudspeaker is adopted to reduce this effect. The implemented algorithms include Roure’s controller, the commonly used LMS-based algorithms, the adaptive spatially feed-forward algorithm, and the optimal controller derived from convex programming. In the narrowband attenuation, we consider not only the fixed harmonic noise but also the varied operating frequency problem. The proposed methods are realized on the platform of a TMS320C32 floating point digital signal processor (DSP) equipped with four 16-bit analog IO channels and they are proven to be valid from the detailed design, analysis, and implementation for the experimental duct system.