適用於可攜式電子鼻系統之氣體辨識方法

Analysis and Design of Portable Electronic Nose Systems

宋俊緯(Jyun-Wei Sung)

指導教授 ： 徐爵民

國立清華大學/電機資訊學院/資訊工程學系/碩士(2010年)

摘要

電子鼻雖然已經行之有年，但其具體實現至今仍然停留在大型儀器。一方面，目前電子鼻系統對於單一已知氣體的辨識演算法已有相當程度的準確率，但是對於測試氣體中含有未知氣體的情形，則尚未有有效的演算法。然而，除了在實驗室中能產生單一氣體的環境，日常生活所遇到的應用，空氣中實際上都是包含了未知氣體成份的環境。本論文將未知氣體視為一個未歸類的氣體(不屬於訓練資料庫中的任何一個類別的氣體)，並設計一個排除機制以避免誤判，以提高氣體辨識正確率。
另一方面，現行技術主要是利用多組感測器的結合，以同時偵測多種氣體，但卻也使得整個偵測系統的體積相當大。本論文嘗試從規格與實際應用考量來設計可攜式電子鼻系統晶片，並實際驗證其可行性。

關鍵字

電子鼻 ； 氣體分析 ； K-最鄰近分類法 ； 異常偵測方法

並列摘要

Electronic nose systems have been used to detect odorous molecules in industrial and environmental applications. Most existing algorithms for such applications are based on the concept of nearest-neighbor classification which computes the "distance" between the test odor and a set of known odors (also called training odors), and may erroneously classify an unknown odor as an odor in the training data set. In this thesis, we propose to improve
the situation by treating the unknown odor (if not belonging to the training data set) as an unclassified odor, and use an outlier rejection mechanism to
avoid misjudgment. We also designed and fabricated an integrated system chip (containing sensor interface circuitry, analog-to-digital converter, 8-bit
microcontroller, and memory) for use in a portable electronic nose system. Experimental results are shown to justify the effectiveness of our proposed algorithm and integrated chip.

並列關鍵字

Electronic Nose ； Odor Analysis ； K-Nearest Neighbor Classifier ； outlier detection

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