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研究生: 沈世評
Shi-Ping Shen
論文名稱: 用線性鑑別分析法做冥想四個方向的分類
Distinguishing the four Directions in Meditation through Linear Disciminant Analysis
指導教授: 葉榮木
Yeh, Zong-Mu
學位類別: 碩士
Master
系所名稱: 機電工程學系
Department of Mechatronic Engineering
論文出版年: 2005
畢業學年度: 93
語文別: 中文
論文頁數: 60
中文關鍵詞: 大腦人機介面腦電波線性鑑別分析法
英文關鍵詞: BCI, EEG, LDA
論文種類: 學術論文
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  • 大腦人機介面(Brain-computer interface)是一種利用腦部訊號跟外界溝通的新技術,其目的是能夠幫助因神經肌肉損傷而行動受阻礙的人。對於內部刺激—想像左右手和腳動—已經有研究過了,但冥想四個方向是值得去研究。有鑑於此,本研究建立一套系統,它以冥想四個方向實驗的腦波訊號作為輸入訊號並利用快速傅立葉分析法找出腦波的特徵,然後利用線性鑑別分析法來分辨這些特徵。最後找出一組可以分辨冥想四個方向的腦波。
    經由實驗結果得知,此系統可以利用實驗中分辨率最高的資料做為參考腦波,最佳的分辨率可達80%以上。未來可預計將此運用於人機介面上以造福神經疾病患者或行動不便人士。

    The brain-computer interface (brain-computer interface) is a kind of new technology of utilizing brain signals to communicate with the external world. Its purpose is to help the person who is hindered take action because his neural muscle is damaged. Internal stimuli, such as imaging right-hand, left-hand, and foot moving, have been studied, but imaging four directions in meditation is worth being studied. For this reason, a system is developed, and the EEG of the four directions in meditation is taken as input signals and a fast Fourier analysis is used to find the features of the EEG. Then a linear discriminant analysis is adopted to classify the features. Finally, a set of brain waves, which can distinguish four directions in meditation, is obtained.
    From the experimental results, it is better to use the data which the accuracy of the classification is the highest in the experiment to be the reference material. The best classification rate in the experiment data is more than 80%. In the future study, the system can be applied to brain-computer interface to benefit neural disease persons or disabled persons.

    摘要....................................................I Abstract...............................................II 目錄..................................................III 圖目錄.................................................VI 表目錄................................................VII 第一章 緒論............................................1 一、前言...........................................1 二、研究背景.......................................1 (一)認識腦波..................................1 (二)腦波頻率..................................2 (三)事件相關的電位............................2 (四)腦波擷取系統..............................3 (五)認識冥想..................................5 三、研究動機.......................................5 四、研究目標........................................5 五、研究架構........................................6 六、系統架構........................................8 七、論文架構.......................................10 第二章 文獻探討........................................11 第三章 腦電波分析方法..................................20 一、腦電波的前處理.................................20 二、特徵擷取演算法.................................21 (一)快速傅立葉轉換法...........................22 (二)小波轉換分析...............................25 三、分類器演算法...................................27 (一)線性鑑別分析...............................27 第四章 實驗設備及實驗設計..............................30 一、實驗材料及設備.................................30 (一)受測者.....................................30 (二)本研究實驗的硬體設備.......................31 (三)本研究實驗的軟體設備.......................31 二、實驗硬體架構及器材配置.........................31 三、實驗步驟.......................................32 第五章 實驗結果與討論..................................35 一、快速傅立葉轉換與小波轉換的結果.................35 二、LDA分類器......................................40 三、錯誤率比較與結果分析...........................45 四、討論...........................................50 第六章 結論與未來展望..................................51 一、結論...........................................51 二、未來展望.......................................52 參考文獻...............................................53 附錄...................................................56 圖目錄 圖1.1 四種基本腦電波的頻率分布...........................2 圖1.2 腦電波儀電極配置圖.................................4 圖1.3 研究步驟流程圖.....................................7 圖1.4冥想四個方向的腦波檢測流程圖........................8 圖2.1實驗所用的圖像.....................................11 圖2.2實驗所用的圖像.....................................12 圖2.3虛擬鍵盤判斷的流程圖...............................13 圖2.4實驗所用的圖像.....................................14 圖2.5實驗所用的圖像.....................................15 圖2.6整個系統的示意圖...................................16 圖2.7分類器的對照表.....................................16 圖2.8虛擬鍵盤的示意圖...................................16 圖3.1 想像四個方向之腦電波分析流程......................20 圖3.2 原始腦波圖........................................21 圖3.3 去眼動的腦波圖....................................21 圖3.4 把N/2點的DFT分解成2個N/4點的DFT的流程圖...........24 圖3.5 8點DFT計算的完全分解流程圖.......................24 圖3.6 訊號X經兩次小波分解的流程圖.......................26 圖3.7 原始輸入訊號經多層小波分解後的頻帶分布............27 圖4.1 NeuroScan之NuAmps腦電波儀與實驗用品..............31 圖4.2 腦電波儀電極配置圖................................32 圖4.3 實驗設備示意圖....................................32 圖4.4 調整阻抗值動作....................................33 圖4.5 受測前的實驗圖形................................. 33 圖4.6 提示方向的刺激圖形............................... 34 圖4.7 一次實驗的流程圖................................. 34 圖5.1受測者所有腦電波的頻譜.............................35 圖5.2通道Cz的頻譜.......................................36 圖5.3 (a)載入未進行小波的向上腦電波.....................36 (b)載入未進行小波的向下腦電波...........................36 圖5.4 (a)載入未進行小波的向右腦電波.....................37 (b)載入未進行小波的向左腦電波...........................37 圖5.5 (a)進行小波轉換後的向上腦電波.....................38 (b)進行小波轉換後的向下腦電波...........................38 圖5.6 (a)進行小波轉換後的向右腦電波.....................39 (b)進行小波轉換後的向左腦電波...........................39 圖5.7 S1、S2每一組實驗用FFT做的分辨率..................40 圖5.8 S3、S4每一組實驗用FFT做的分辨率..................41 圖5.9 S1、S2每一組實驗用WT做的分辨率...................41 圖5.10 S3、S4每一組實驗用WT做的分辨率..................42 圖5.11 有明顯特徵的腦電波頻譜...........................42 圖5.12 4個LDA器參數與分類方向之關係圖..................43 圖5.13 S1、S2每一組實驗的分辨率........................45 圖5.14 S3、S4每一組實驗的分辨率........................46 圖5.15 S1、S2明顯的特徵值與分辨率之關係................47 圖5.16 S3、S4明顯的特徵值與分辨率之關係................48 圖5.17 S1、S2明顯的特徵值與無效數據之關係..............48 圖5.18 S3、S4明顯的特徵值與無效數據之關係..............49 表目錄 表2.1世界各地的大腦人機介面系統.........................17 表2.2 BCI系統問題分類...................................19 表5.1 4個LDA器所得到+和一值的查詢方向表................43 表5.2 各個LDA分類器所判定的結果.........................44 表5.3 S1、S2、S3、S4第一次實驗的有效資料數.............46 表5.4 S1、S2、S3、S4第十二組實驗的分辨率...............47 表5.5 調整有效條件到20μv/Hz的分辨率....................49

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