基于改进共空间模式与视觉反馈的闭环脑机接口  

Closed Loop Brain Computer Interface Based on Improved Common Spatial Patterns and Visual Feedback

作　　者：任士鑫 王卫群[1,2] 侯增广 陈霸东[3] 石伟国 王佳星[1,2] 梁旭 REN Shixin;WANG Weiqun;HOU Zengguang;CHEN Badong;SHI Weiguo;WANG Jiaxing;LIANG Xu(Institute of Automation Chinese Academy of Sciences,Beijing 100190;University of Chinese Academy of Sciences,Beijing 100049;Institute of Artificial Intelligence and Robotics Xi'an Jiaotong University,Xi'an 710049)

机构地区：[1]中国科学院自动化研究所,北京100190 [2]中国科学院大学,北京100049 [3]西安交通大学人工智能与机器人研究所,西安710049

出　　处：《机械工程学报》2019年第11期28-35,共8页Journal of Mechanical Engineering

基　　金：国家自然科学基金(91648208,91848110);北京市自然科学基金(3171001,L172050);中国科学院战略性先导科技专项(B类,XDB32000000)资助项目

摘　　要：为提高脑卒中等神经损伤患者在下肢康复训练过程中的主动参与度,设计了基于人体下肢运动想象与视觉反馈的在线闭环脑机接口,并建立了基于互相关熵诱导度量与子频带分析的改进共空间模式算法,提高人体下肢运动意图的识别率。针对运动想象脑电信号信噪比低和难以精确识别等问题,在传统共空间模式算法基础上,利用互相关熵诱导度量准则改进其目标函数,实现了目标函数中距离项属性的动态调整,降低对噪声的敏感性,提高算法鲁棒性;利用脑电信号不同频段蕴含信息不同的特点,使用9个子频带滤波器对信号进行滤波,对每个子频带信号分别提取特征,并进行特征融合,建立基于互相关熵诱导度量与子频带分析的改进共空间模式算法。其次,基于人体下肢运动想象的脑控试验范式,收集下肢运动想象(空想、脚动和腿动)的脑电数据,采用支持向量机(SVM)建立分类模型,优化设计模型参数。在上述研究基础上,建立了以改进共空间模式为特征提取算法,SVM为分类器的脑机接口。进而,在被试执行运动想象的同时,通过虚拟现实场景中虚拟人物的肢体动作给予用户视觉反馈,构建了闭环的脑机交互系统。通过试验验证了改进共空间模式算法的有效性和闭环脑机接口的可行性,初步实现了闭环脑机交互接口。In order to improve the active participation of patients with stroke or nerve injury in the lower limb rehabilitation training,an on-line closed loop brain computer interface is designed based on human lower limb motor imagery and visual feedback.And an improved common spatial pattern algorithm,which based on the correntropy induced metric and sub-frequency band analysis,is established to improve the recognition rate of the motor intention.Due to the low signal noise ratio and classification accuracy of the motor imagery EEG signals,correntropy induced metric is adopted to improve the objective function of the traditional common spatial patterns(CSP).The distance term of the objective function can be adjusted dynamically to alleviate the negative effects of noise.Because the different frequency band signals have different information,nine sub-frequency bandpass filters are used to filter the signal.And the features extracted from each sub-band signal are fused.Therefore,the improved common spatial pattern algorithm based on the correntropy induced metric and sub-frequency band analysis is established.Then,based on the brain control experiment paradigm of human lower limb motor imagery,EEG data of lower limbs motor imagery(idle,foot and leg)are collected.Support vector machine(SVM)is optimized as a classification model for the motor imagery.Based on the study above,a brain computer interface based on improved common spatial pattern algorithm and SVM is built.When participant images the movements,the user's visual feedback is given to the user through the body movements of the virtual character in the virtual reality scene,and a closed loop brain computer interaction system is constructed.Experiments verified the effectiveness of the improved common space algorithm and the feasibility of closed-loop brain computer interface,and the closed loop interaction between the brain and computer is achieved initially.

关 键 词：运动想象 脑机接口 互相关熵诱导度量 共空间模式 

分 类 号：TG156[金属学及工艺—热处理]