Identification of motion from multi-channel EMG signals for control of prosthetic hand

The authors in this paper propose an effective and efficient pattern recognition technique from four channel electromyogram (EMG) signals for control of multifunction prosthetic hand. Time domain features such as mean absolute value, number of zero crossings, number of slope sign changes and waveform length are considered for pattern recognition. The patterns are classified using simple logistic regression (SLR) technique and decision tree (DT) using J48 algorithm. In this study six specific hand and wrist motions are identified from the EMG signals obtained from ten different able-bodied. By considering relevant dominant features for pattern recognition, the processing time as well as memory space of the SLR and DT classifiers is found to be less in comparison with neural network (NN), k-nearest neighbour model 1 (kNN-Model-1), k-nearest neighbour model 2 (kNN-Model-2) and linear discriminant analysis. The classification accuracy of SLR classifier is found to be 91 ± 1.9%.     

Identification of a feature selection based pattern recognition scheme for finger movement recognition from multichannel EMG signals

This paper focuses on identification of an effective pattern recognition scheme with the least number of time domain features for dexterous control of prosthetic hand to recognize the various finger movements from surface electromyogram (EMG) signals. Eight channels EMG from 8 able-bodied subjects for 15 individuals and combined finger activities have been considered in this work. In this work, an attempt has been made to recognize a number of classes with the least number of features. Therefore, EMG signals are pre-processed using dual tree complex wavelet transform to improve the discriminating capability of features and time domain features such as zero crossing, slope sign change, mean absolute value, and waveform length is extracted from the pre-processed data. The performance of extracted features is studied with different classifiers such as linear discriminant analysis, naive Bayes classifier, quadratic support vector machine and cubic support vector machine with and without feature selection algorithms. The feature selection has been studied using particle swarm optimization (PSO) and ant colony optimization (ACO) with different number of features to identify the effect of features. The results demonstrated that naive Bayes classifier with ant colony optimization shows an average classification accuracy of 88.89% with a response time of 0.058025 ms for recognizing the 15 different finger movements with 16 features with significant difference in accuracy compared to SVM classifier with feature selection for a significance level of 0.05. There is no significant difference in the accuracy, specificity and sensitivity of an SVM classifier with and without feature selection. But the processing time is significantly more than the LDA and NB classifier. The PSO and ACO results revealed that slope sign changes contribute to recognizing the activity. In PSO, mean absolute value has been found to be effective compared to waveform length, contradictory with ACO. Further, the zero crossings have been found to be not effective in classification of finger movements in both the methods.     

基于多尺度主元分析的表面肌电信号模式分类

用基于小波变换的多尺度主元分析提取表面肌电信号特征,然后用贝叶斯分类器进行模式分类。实验结果显示,当选用Harr小波和bior2．6小波对肌电信号进行5层小波分解时．该方法对前臂6种动作模式（内翻,外翻．握拳．展拳．上切和下切）的正确识别率可以达到99.44％。研究表明,该方法优于基于小波系数统计特征和主元分析降维相结合的特征提取方法．能成功识别出多种动作模式。     

基于短时傅里叶变换的肌电信号识别方法

针对肌电信号的非平稳特性,采用短时傅里叶变换方法对表面肌电信号进行分析,并通过奇异值分解有效地提取特征矢量进行模式识别,能够成功地从掌长肌和肱桡肌采集的两道表面肌电信号中识别展拳、握拳、腕内旋、腕外旋四种运动模式。实验表明,基于短时傅里叶变换的奇异值分解方法是一种稳定、有效的特征提取方法。     

基于模糊小波包和决策树的表面肌电信号分类研究

提出了用模糊小渡包提取表面肌电信号特征，并且用C4．5决策树分类器对信号进行分类的方法。通过对4类不同的动作肌电信号进行分类，验证了该方法的有效性和高识别率。     

Diagnosis of multiple sclerosis from EEG signals using nonlinear methods

EEG signals have essential and important information about the brain and neural diseases. The main purpose of this study is classifying two groups of healthy volunteers and Multiple Sclerosis (MS) patients using nonlinear features of EEG signals while performing cognitive tasks. EEG signals were recorded when users were doing two different attentional tasks. One of the tasks was based on detecting a desired change in color luminance and the other task was based on detecting a desired change in direction of motion. EEG signals were analyzed in two ways: EEG signals analysis without rhythms decomposition and EEG sub-bands analysis. After recording and preprocessing, time delay embedding method was used for state space reconstruction; embedding parameters were determined for original signals and their sub-bands. Afterwards nonlinear methods were used in feature extraction phase. To reduce the feature dimension, scalar feature selections were done by using T-test and Bhattacharyya criteria. Then, the data were classified using linear support vector machines (SVM) and k-nearest neighbor (KNN) method. The best combination of the criteria and classifiers was determined for each task by comparing performances. For both tasks, the best results were achieved by using T-test criterion and SVM classifier. For the direction-based and the color-luminance-based tasks, maximum classification performances were 93.08 and 79.79% respectively which were reached by using optimal set of features. Our results show that the nonlinear dynamic features of EEG signals seem to be useful and effective in MS diseases diagnosis.     

Hand movements classification for myoelectric control system using adaptive resonance theory

This research proposes an exploratory study of a simple, accurate, and computationally efficient movement classification technique for prosthetic hand application. Surface myoelectric signals were acquired from the four muscles, namely, flexor carpi ulnaris, extensor carpi radialis, biceps brachii, and triceps brachii, of four normal-limb subjects. The signals were segmented, and the features were extracted with a new combined time-domain feature extraction method. Fuzzy C-means clustering method and scatter plot were used to evaluate the performance of the proposed multi-feature versus Hudgins’ multi-feature. The movements were classified with a hybrid Adaptive Resonance Theory-based neural network. Comparative results indicate that the proposed hybrid classifier not only has good classification accuracy (89.09 %) but also a significantly improved computation time.     

Epileptic seizure detection in EEG signal using machine learning techniques

Epilepsy is a well-known nervous system disorder characterized by seizures. Electroencephalograms (EEGs), which capture brain neural activity, can detect epilepsy. Traditional methods for analyzing an EEG signal for epileptic seizure detection are time-consuming. Recently, several automated seizure detection frameworks using machine learning technique have been proposed to replace these traditional methods. The two basic steps involved in machine learning are feature extraction and classification. Feature extraction reduces the input pattern space by keeping informative features and the classifier assigns the appropriate class label. In this paper, we propose two effective approaches involving subpattern based PCA (SpPCA) and cross-subpattern correlation-based PCA (SubXPCA) with Support Vector Machine (SVM) for automated seizure detection in EEG signals. Feature extraction was performed using SpPCA and SubXPCA. Both techniques explore the subpattern correlation of EEG signals, which helps in decision-making process. SVM is used for classification of seizure and non-seizure EEG signals. The SVM was trained with radial basis kernel. All the experiments have been carried out on the benchmark epilepsy EEG dataset. The entire dataset consists of 500 EEG signals recorded under different scenarios. Seven different experimental cases for classification have been conducted. The classification accuracy was evaluated using tenfold cross validation. The classification results of the proposed approaches have been compared with the results of some of existing techniques proposed in the literature to establish the claim.     

A sparse Bayesian learning based scheme for multi-movement recognition using sEMG

This paper proposed a feature extraction scheme based on sparse representation considering the non-stationary property of surface electromyography (sEMG). Sparse Bayesian learning was introduced to extract the feature with optimal class separability to improve recognition accuracy of multi-movement patterns. The extracted feature, sparse representation coefficients (SRC), represented time-varying characteristics of sEMG effectively because of the compressibility (or weak sparsity) of the signal in some transformed domains. We investigated the effect of the proposed feature by comparing with other fourteen individual features in offline recognition. The results demonstrated the proposed feature revealed important dynamic information in the sEMG signals. The multi-feature sets formed by the SRC and other single feature yielded more superior performance on recognition accuracy, compared with the single features. The best average recognition accuracy of 94.33 % was gained by using SVM classifier with the multi-feature set combining the feature SRC, Williston amplitude (WAMP), wavelength (WL) and the coefficients of the fourth order autoregressive model (ARC4) via multiple kernel learning framework. The proposed feature extraction scheme (known as SRC + WAMP + WL + ARC4) is a promising method for multi-movement recognition with high accuracy.     

基于BP神经网络的表面肌电信号模式分类的研究

将神经网络与AR模型相结合提出了一种表面肌电信号模式分类算法。该算法能成功地从腕伸肌和腕屈肌的两道表面肌电信号中识别脱伸、腕屈、腕内旋和腕外旋四种运动模式。实验结果表明：用AR模型参数作BP网输入的肌电模式分类器，运行速度快、识别率高、鲁棒性好，在假肢等人一机仿生系统的控制中具有很好的应用前景。     

基于Relief特征选择算法与多生理信号的焦虑状态识别

焦虑是一种在感到被威胁的环境中产生的复杂的心理过程。该文通过任务驱动的焦虑情绪诱发实验,采集被试心电、呼吸、血容量搏动、皮肤电四种生理信号数据,结合Relief算法对特征进行选择,并结合k近邻算法（kNN）和支持向量机（SVM）算法,对平静状态和焦虑情绪状态进行识别分类。结果表明,对于焦虑情绪状态下的情绪识别,Relief-SVM算法优于Relief-kNN算法;利用多生理参数进行情绪识别优于单一生理参数。     

影像组学在肺肿瘤良恶性分类预测中的应用研究

针对肺癌临床诊断中缺乏定量评估方法等问题,本研究采用影像组学方法构建基于支持向量机(SVM)的肺肿瘤良恶性分类预测模型。首先介绍了影像组学的定义、处理流程。实验样本选自公开数据集LIDC上的816例肺癌患者的CT影像数据。先采用中心池化卷积神经网络分割法提取感兴趣区(ROI),然后分别采用影像组学特征提取包Pyradiomics和FSelector特征筛选模型进行特征提取和特征降维,最后通过SVM构建肺肿瘤良恶性分类预测模型。模型对大于5 mm肺小结节的良恶性分类的预测准确率为80.4%,曲线下面积(AUC)的值为0.792,表明SVM分类器模型可以准确地判别大于5 mm的肺小结节的良恶性。     

Neural networks for detection and classification of walking pattern changes due to ageing

With age, gait functions reflected in the walking patterns degenerate and threaten the balance control mechanisms of the locomotor system. The aim of this paper is to explore applications of artificial neural networks for automated recognition of gait changes due to ageing from their respective gait-pattern characteristics. The ability of such discrimination has many advantages including the identification of at-risk or faulty gait. Various gait features (e.g., temporal-spatial, foot-ground reaction forces and lower limb joint angular data) were extracted from 12 young and 12 elderly participants during normal walking and these were utilized for training and testing on three neural network algorithms (Standard Backpropagation: Scaled Conjugate Gradient; and Backpropagation with Bayesian Regularization, BR). Receiver operating characteristics plots, sensitivity and specificity results as well as accuracy rates were used to evaluate performance of the three classifiers. Cross-validation test results indicate a maximum generalization performance of 83.3% in the recognition of the young and elderly gait patterns. Out of the three neural network algorithms, BR performed superiorly in the test results with best sensitivity, selectivity and detection rates. With the help of a feature selection technique, the maximum classification accuracy of the BR attained 100%, when trained with a small subset of selected gait features. The results of this study demonstrate the capability of neural networks in the detection of gait changes with ageing and their potentials for future applications as gait diagnostics.     

Classifying dysmorphic syndromes by using artificial neural network based hierarchical decision tree

Dysmorphic syndromes have different facial malformations. These malformations are significant to an early diagnosis of dysmorphic syndromes and contain distinctive information for face recognition. In this study we define the certain features of each syndrome by considering facial malformations and classify Fragile X, Hurler, Prader Willi, Down, Wolf Hirschhorn syndromes and healthy groups automatically. The reference points are marked on the face images and ratios between the points’ distances are taken into consideration as features. We suggest a neural network based hierarchical decision tree structure in order to classify the syndrome types. We also implement k-nearest neighbor (k-NN) and artificial neural network (ANN) classifiers to compare classification accuracy with our hierarchical decision tree. The classification accuracy is 50, 73 and 86.7% with k-NN, ANN and hierarchical decision tree methods, respectively. Then, the same images are shown to a clinical expert who achieve a recognition rate of 46.7%. We develop an efficient system to recognize different syndrome types automatically in a simple, non-invasive imaging data, which is independent from the patient’s age, sex and race at high accuracy. The promising results indicate that our method can be used for pre-diagnosis of the dysmorphic syndromes by clinical experts.     

脑-机接口驱动神经义肢手系统的研究

本文针对现代医疗手段还无法使上臂再生的问题,深入分析了人手动作脑电信号的特点,研究了面向义肢手控制的手动作脑电小波特征提取和BP神经网络模式识别方法,开发研制了一个基于BCI（Brain-Computer Interface,简称BCI）驱动的神经义肢手驱动控制系统,并用该系统完成了义肢手四种动作（手臂自由状态、手臂移动、手抓取、手张开）的驱动。经过多次在线及离线实验,结果表明：基于脑-机接口驱动的神经义肢手系统是合理可行的,所采用的脑电信号小波特征提取方法和BP神经网络模式识别方法是有效的。     

基于SVM的尿液粒子识别算法研究

本文将支持向量机的算法引入到尿沉渣有形成分的分类问题上.在提取特征的基础上,采用交叉验证法和精度等高线图进行核函数及参数的选择.根据支持向量机和数据集特点,设计出由两级分类器集成的支持向量机多分类器.得到了相应的混淆矩阵.临床实验数据分类评测以及与神经网络方法比较结果表明,提出的算法具有一定的优势.     

用LM算法改进的BP网络在表面肌电信号识别中的应用研究

提出用Levenberg-Marquardt算法改进BP神经网络识别表面肌电信号的方法.采用多尺度小波变换对肌电信号进行分析,提取各尺度下小波系数幅值的最大和最小值构造特征矢量,输入BP神经网络可进行模式识别,经过训练能够成功地从表面肌电信号中识别展拳、握拳、前臂内旋、前臂外旋四种运动模式.实验表明,LM算法在响应时间和识别精度上都比标准的BP算法有了很大提高.     

Spectral feature extraction of EEG signals and pattern recognition during mental tasks of 2-D cursor movements for BCI using SVM and ANN

Brain computer interface (BCI) is a new communication way between man and machine. It identifies mental task patterns stored in electroencephalogram (EEG). So, it extracts brain electrical activities recorded by EEG and transforms them machine control commands. The main goal of BCI is to make available assistive environmental devices for paralyzed people such as computers and makes their life easier. This study deals with feature extraction and mental task pattern recognition on 2-D cursor control from EEG as offline analysis approach. The hemispherical power density changes are computed and compared on alpha–beta frequency bands with only mental imagination of cursor movements. First of all, power spectral density (PSD) features of EEG signals are extracted and high dimensional data reduced by principle component analysis (PCA) and independent component analysis (ICA) which are statistical algorithms. In the last stage, all features are classified with two types of support vector machine (SVM) which are linear and least squares (LS-SVM) and three different artificial neural network (ANN) structures which are learning vector quantization (LVQ), multilayer neural network (MLNN) and probabilistic neural network (PNN) and mental task patterns are successfully identified via k-fold cross validation technique.     

Characterization of surface electromyography using time domain features for determining hand motion and stages of contraction

Surface electromyography (SEMG) signals can provide important information for prosthetic hand control application. In this study, time domain (TD) features were used in extracting information from the SEMG signal in determining hand motions and stages of contraction (start, middle and end). Data were collected from ten healthy subjects. Two muscles, which are flexor carpi ulnaris (FCU) and extensor carpi radialis (ECR) were assessed during three hand motions of wrist flexion (WF), wrist extension (WE) and co-contraction (CC). The SEMG signals were first segmented into 132.5 ms windows, full wave rectified and filtered with a 6 Hz low pass Butterworth filter. Five TD features of mean absolute value, variance, root mean square, integrated absolute value and waveform length were used for feature extraction and subsequently patterns were determined. It is concluded that the TD features that were used are able to differentiate hand motions. However, for the stages of contraction determination, although there were patterns observed, it is determined that the stages could not be properly be differentiated due to the variability of signal strengths between subjects.     

多进制小波在医学图像检索中的应用

医学影像的数据量日益增加使得建立一个高效的医学检索系统势在必行，而提高检索系统效率的关键技术就是合理地分类图像。纹理作为图像灰度的分布模式，是图像的重要特征之一。由于图像的小渡多尺度分解本质上是一种多通道的滤波过程，其多分辨率分析结构与人类视觉系统特性相一致。因而，在图像的多进制小坡变换域中提取不同分辨率下的纹理特征，特别有利于图像识别与检索。文中设计并实现了一种基于八进制小波的医学图像分类方法，更好地解决了医学图像检索的关键技术，得到了很高的分类率。