Chernof f加權(quán)分類器框架在運動想象腦-機(jī)接口中的應(yīng)用
doi: 10.11999/JEIT181132
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湖南工商大學(xué)新零售虛擬現(xiàn)實技術(shù)湖南省重點實驗室 長沙 410205
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2.
中南大學(xué)自動化學(xué)院 長沙 410083
Applying Chernoff Weighted Classification Frame Method to MotorImagery Brain Computer Interface
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Key Laboratory of Hunan Province for New Retail Virtual Reality Technology, Hunan University ofTechnology and Business, Changsha 410205, China
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2.
School of Automation, Central South University, Changsha 410083, China
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摘要:
針對現(xiàn)有腦機(jī)接口(BCI)分類器與大腦認(rèn)知過程結(jié)合不夠緊密的問題,該文提出一種基于Chernoff加權(quán)的分類器集成框架方法,并用于同步運動想象腦機(jī)接口中。通過對訓(xùn)練數(shù)據(jù)進(jìn)行統(tǒng)計分析,獲得各時刻腦電信號(EEG)的統(tǒng)計特性,并建立基于大腦認(rèn)知過程的高斯概率模型。然后利用Chernoff邊界特性得到該概率模型的最小誤差,并以此確定該時刻分類器的權(quán)重,通過對各時刻分類器的加權(quán),實現(xiàn)同步腦機(jī)接口的信號分類。以腦機(jī)接口競賽數(shù)據(jù)作為測試,并與線性判決分析、支持向量機(jī)和極限學(xué)習(xí)方法分別結(jié)合構(gòu)成新的集成方法。由實驗結(jié)果可知,加權(quán)集成框架方法的分類性能比原獨立分類方法有顯著提高。
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關(guān)鍵詞:
- 腦機(jī)接口 /
- 運動想象 /
- 概率模型 /
- Chernoff誤差邊界 /
- 模式分類
Abstract:For the problem that the classifier is less considered to be combined with the brain's cognitive process in the Brain-Computer Interface (BCI) system, a Chernoff-weighted based classifier integrated frame method is proposed and used in synchronous motor imagery BCI. In the method, the statistic characteristics of ElectroEncephaloGraphy (EEG) are obtained by analyzing in each time point of synchronous BCI, and then the probability model is established to compute the Chernoff error bound, which is adopted as the weight of common classifier to take the discriminant process. The test experiments are based on the datasets from BCI competitions, and the proposed frame method is employed to compose with LDA, SVM, ELM respectively. The experimental results demonstrate that the proposed frame method shows competitive performance compared with other methods.
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表 1 算法1 Chernoff框架方法的訓(xùn)練過程
輸入:EEG訓(xùn)練數(shù)據(jù) 輸出:獨立分類器模型參數(shù)和概率權(quán)重w 步驟 1 對EEG數(shù)據(jù)進(jìn)行預(yù)處理,提取特征向量; 步驟 2 利用獨立分類器訓(xùn)練得到模型參數(shù); 步驟 3 利用式(1)得到特征向量的均值和方差; 步驟 4:利用式(8)得到權(quán)重w。 下載: 導(dǎo)出CSV
表 2 算法2 Chernoff框架方法的測試過程
輸入:t 時刻的測試 EEG 數(shù)據(jù),獨立分類器參數(shù)和權(quán)重w 輸出:分類結(jié)果和判定值dout(t) 步驟 1 對EEG數(shù)據(jù)進(jìn)行預(yù)處理,提取特征向量; 步驟 2 通過獨立分類器的訓(xùn)練模型得到yc(t); 步驟 3 利用式(11)和式(12)將yc轉(zhuǎn)化到p(t)∈[0, 1]; 步驟 4 利用式(9)計算pout(t); 步驟 5 利用式(10)將pout(t) 變換到dout(t)∈[–1, 1]; 步驟 6 通過dout(t)的符號獲得分類結(jié)果。 下載: 導(dǎo)出CSV
表 3 實驗中的數(shù)據(jù)集
序號 數(shù)據(jù)集來源 訓(xùn)練集個數(shù)(試驗次數(shù)) 測試集個數(shù)(試驗次數(shù)) 類別 1 BCI II (III) 1 (140) 1 (140) 2 2 BCI III (IIIb) 1 (320) 1 (320) 2 3 BCI IV (IIb) 3 (400) 2 (320) 2 4 BCI IV (IIb) 3 (400) 2 (320) 2 下載: 導(dǎo)出CSV
表 4 數(shù)據(jù)集1的最大互信息(bit)
分類方法 最大互信息 ELM 0.524/0.051 LDA 0.414 SVM 0.471 LSTM 0.511 ELM-CF 0.680/0.020 LDA-CF 0.631 SVM-CF 0.662 第II屆BCI競賽的第1名 0.61 下載: 導(dǎo)出CSV
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