华中科技大学硕士学位论文
摘要
冻结步态（Freezing of gait, FOG）是中晚期帕金森病（Parkinson’s disease, PD）患者最常见的步态障碍，极易导致患者跌倒并对其身心健康及生活质量产生严重的影响。带有节律性听觉刺激的可穿戴系统可作为干预FOG的辅助工具，减少发病患者的跌倒风险。冻结步态检测作为该系统的基础，还可为病情评估提供相关症状信息，具有重要的研究意义和应用价值。 本文设计了相关实验流程，采集了12名PD患者的冻结步态信号，其中运动传感器被部署在患者腰部、左右大腿等9个位置。实验总共记录了2小时31分钟的数据，10名患者在试验期间表现出FOG，专业医师从视频记录中共识别出276个FOG事件。在此基础上，本文围绕冻结步态检测过程中的划分时间窗、特征提取与选择、分类等问题展开了系统的研究。
本文对传感器各轴信号提取了13个典型时频域特征。针对高维特征空间引起的分类精度下降和计算开销大等问题，选取互信息和方差分析这两种特征选择方法对特征重要性进行了评价并比较了两种方法的有效性。本文评估了单一传感器和多传感器组合的检测效果，并使用方差分析为几种传感器配置选择了最佳特征。在综合考虑检测性能、成本及实际部署要求等因素后，选择左小腿加速度计和陀螺仪的组合作为最佳传感器配置并为其选取了35个最佳特征。本文将随机森林、AdaBoost、线性判别分析、多层感知
神经网络应用于冻结步态分类算法设计中，研究了正负样本比例和时间窗大小对分类器性能的影响，逐步优化了检测模型的性能。最终结果表明，当以1.25s时间窗、0.15s步长进行滑窗采样，提取左小腿加速度计和陀螺仪各轴的35个特征作为特征向量并使用由正负样本比例为1的样本集训练得到的AdaBoost模型进行分类时，可获得87.3%灵敏度，91.2%特异性，89.5%AUC的最佳检测效果。
关键词：帕金森病，冻结步态，传感器配置，特征选择，模式分类
轻触开关电路华中科技大学硕士学位论文
Abstract
Freezing of gait (FOG) is a common gait disorder among patients with advanced Parkinson's disease, which is associated with falls and negatively impact the patient's quality of life. Wearable systems with rhythmic auditory stimulation can be applied to help patients resume walking and reduce the risk of falls. As the basis of the system, the detection of freezing of gait can also provide relevant information for disease assessment, which has important research significance and application value.
The thesis designed the relevant experimental procedures to obtain FOG signals from PD patients.
Accelerometers and gyroscopes were placed on the patient's waist, left calve, right calve and the remaining 6 body parts. A total of 2 hours and 31 minutes of data was recorded in the experiment. Signals recorded from 10 patients with PD who presented the symptom of FOG and 2 patients who suffered from PD but they do not present FOG events. Professional physicians identified 276 FOG events from video recordings. On this basis, the research is carried out around segmentation, feature extraction, and classification.
In this thesis, 13 typical time-frequency domain features were extracted from the sensor signals.Due to the low classification accuracy and high computational cost caused by high-dimensional feature space, mutual information and analysis of variance were selected to evaluate the importance of features and the effectiveness of the two methods were compared. The thesis evaluated the detection effects using several different configurations of sensors in order to conclude to the set of sensors which can produce optimal FOG episode detection and selected the best features for the optimal sensor configuration.After that, random forest, AdaBoost, linear discriminant analysis, and multi-layer perceptual neural network algorithm were applied to classification. The effects of the ratio of positive to negative samples and window size on classifier performance were studied, and the performance of the detection model was gradually optimized. The final results indicated that the proposed model was able to detect FOG
华中科技大学硕士学位论文
events with 87.3% sensitivity, 91.2% specificity, 89.5% AUC when using 1.25s time window (125 sample points) and 0.15s (15 sample points) step, the 35 features obtained from the gyro and accelerometer placed on patients’ left shank and AdaBoost classifier.
Keywords: Parkinson’s disease, Freezing of gait, Sensor configuration, Feature selection, Pattern classification
华中科技大学硕士学位论文
目录
摘要....................................................................................................... I ABSTRACT ............................................................................................. II 目录.................................................................................................... IV 第一章绪论 (1)
1.1课题研究背景及意义 (1)
1.2国内外研究现状及分析 (4)液晶显示片
1.3本文工作及组织框架 (7)
第二章冻结步态信号采集及样本集获取 (10)
2.1基于运动感知的冻结步态检测过程及其检测性能指标 (10)
2.2冻结步态信号采集 (12)
2.3数据预处理 (16)
2.4样本集获取 (18)
2.5本章小结 (20)
取石网篮第三章冻结步态特征选择及传感器配置评估 (21)
3.1冻结步态特征提取 (21)
3.2特征选择方法的研究 (25)
3.3传感器配置评估及特征选择 (31)
3.4本章小结 (35)
第四章冻结步态识别方法的研究 (36)
华中科技大学硕士学位论文
4.1分类算法性能的影响因素 (36)
flag标签抗体4.2分类算法设计 (39)
超前支架
光缆接线盒4.3实验结果与分析 (46)
4.4冻结步态识别结果与分析 (50)
4.5本章小结 (51)
第五章总结与展望 (52)
5.1总结 (52)
5.2展望 (54)
致谢 (55)
参考文献 (56)
附录攻读硕士学位期间发表的论文与专利 (61)
