非接触式生理信号检测关键技术研究

发布时间：2018-04-06 20:07

本文选题：成像式光电容积描记技术　切入点：非接触式　出处：《北京理工大学》2014年博士论文

【摘要】：成像式光电容积描记(imaging photoplethysmography, IPPG)技术是近几年在传统光电容积描记(PPG)技术基础上发展起来的一种非接触式生理信号检测技术。IPPG技术以其非接触测量、低成本、易操作等特点，尤其是非接触测量方式使其能够实现一些特定情况下的临床及日常检测，如被检测部位具有开放性伤口及运动状态下的生理信号检测，已成为仪器及生物医学工程领域的新兴研究热点之一。目前虽然已通过IPPG技术实现了一些重要生理信号的测量，如心率、呼吸率等，但其在更稳定、更全面的生理信号测量等方面还存在一些关键问题有待解决。本文在系统分析IPPG技术的光学及生理学原理的基础上，讨论了IPPG的技术特点，对IPPG技术中存在的关键问题进行了分析总结并提出了相应的解决办法。本文开展的具体研究内容及结果如下所述： (1)从光学与生理学角度出发对IPPG技术的进行了详细分析，在此基础上，分析了IPPG的技术特点，对IPPG技术中的关键技术包括测量部位选取、不同生理参数对成像设备性能要求、视频图像信号处理等技术进行了分析总结，并指出了其存在的主要问题。 (2)对IPPG系统的关键技术进行分析的基础上，结合血氧饱和度测量原理，指出现有IPPG系统由于易受环境光干扰而不适合进行血氧饱和度的提取。针对于现有IPPG系统的不足，提出了采用窄带滤光片结合双低照度CCD的视频采集方案，并从硬件及软件两方面设计了适合于血氧饱和度测量的IPPG系统平台。在此基础上，通过实验分析血氧饱和度参数R与PPG系统测得血氧饱和度值的线性度确定了血氧饱和度测量双波长520nm与660nm。 (3)对设计开发的IPPG系统在血氧饱和度测量方面的可行性及性能进行了实验研究。设计了屏息及静息状态下的两种不同实验。通过屏息实验对血氧饱和度经验常数进行了标定，并利用已标定的IPPG系统与传统PPG系统进行了对比测试。研究结果表明自主设计的IPPG系统能够实现环境光下的血氧饱和度测量，并且与PPG系统在心率及血氧饱和度测量方面具有较高的一致性，，误差在4%以内。研究结果拓展了IPPG技术在生理信号测量方面的应用。 (4)在上述研究基础上，分析了低端彩色成像设备在血氧饱和度测量方面的可行性与局限性。根据彩色成像设备RGB三通道成像特点，提出利用成像设备的红、蓝两通道来代替传统PPG信号的红及红外两通道信号的血氧饱和度提取方法，同时搭建了基于彩色CCD的非接触式血氧饱和度测量系统。实验及分析结果表明：基于彩色相机的测量系统受红、蓝通道带宽较宽的限制，其测量结果虽能体现出血氧饱和度的变化，但测量结果误差较大，不适合应用于日常及临床监护。 (5)进行了IPPG技术在脉搏变异信号(pulse rate variability, PRV)检测方面的可行性分析，搭建了基于高速成像设备的IPPG系统，分别利用时域、频域及时频联合分析的方法对系统测得的脉搏变异信号进行了分析。通过与传统PPG系统、心电信号测量系统(ECG)所测得的结果对比分析，结果表明IPPG系统与上述两系统在脉搏变异信号测量方面具有较高的一致性。研究结果证明IPPG系统在高速信号采集方面的技术可行性，并指出其有望应用于脉搏波传递时间、血压等的测量。上述研究为早日实现多种生理信号同时测量的IPPG系统提供了理论及技术支持。 (6)为提高IPPG系统的实际应用能力，重点探讨了盲源分离技术在IPPG系统运动伪差消除方面的应用。针对彩色成像设备采集到的RGB三通道信号特点，提出采用敏感区域跟踪匹配结合独立分析的方法去除运动伪差；针对黑白成像设备采集单色信号特点，在信号后期处理阶段采用单通道独立分量分析的方法，成功分离出了脉搏波信号。利用该方法提取出的心率信息与传统PPG系统检测结果具有较好的一致性，这一结果表明IPPG系统在心率信号测量方面具有较强的实际应用能力。
[Abstract]:IPPG is a kind of non - contact physiological signal detection technique developed on the basis of traditional photoelectric volume tracing ( PPG ) technology in recent years . The IPPG technique is one of the hot topics in the field of instrument and biomedical engineering .

Based on the systematic analysis of the optical and physiological principles of IPPG technology , this paper discusses the technical features of IPPG , analyzes the key problems existing in IPPG technology , and puts forward some solutions . The specific research contents and results are as follows :

( 1 ) Based on the detailed analysis of IPPG technology from the point of view of optics and physiology , this paper analyzes the technical features of IPPG , analyzes the key technologies in IPPG technology , including measurement site selection , different physiological parameters , analyzes and summarizes the performance requirements of imaging equipment , video image signal processing and so on , and points out its main problems .

( 2 ) Based on the analysis of key technologies of IPPG system , combined with the principle of blood oxygen saturation measurement , it is pointed out that the existing IPPG system is not suitable for the extraction of blood oxygen saturation due to the disturbance of ambient light .

( 3 ) The feasibility and the performance of IPPG system in the measurement of blood oxygen saturation were studied experimentally . Two different experiments were carried out in breath - hold and resting state . The experimental results show that the self - designed IPPG system can realize the measurement of blood oxygen saturation under ambient light . The results show that the self - designed IPPG system has high consistency in the measurement of heart rate and blood oxygen saturation , and the error is within 4 % . The results of the study have expanded the application of IPPG technique in physiological signal measurement .

( 4 ) Based on the above research , the feasibility and limitation of the low - end color imaging equipment in the measurement of blood oxygen saturation are analyzed . According to the characteristics of RGB three - channel imaging of color imaging equipment , the red and blue channels of the imaging equipment are used to replace the blood oxygen saturation extraction method of the red and infrared two - channel signals of the traditional PPG signal .

( 5 ) The feasibility of IPPG technique in pulse rate variability ( PRV ) detection is analyzed . The pulse variation signal is analyzed by means of time - domain and frequency - domain time - frequency joint analysis . The results show that the IPPG system has high consistency in pulse variation signal measurement . The results show that the IPPG system is hopeful to be applied to the measurement of pulse wave delivery time , blood pressure , etc . The research provides the theory and technical support for the early realization of multiple physiological signals .

( 6 ) In order to improve the practical application ability of IPPG system , the application of blind source separation technology in the elimination of motion artifacts in IPPG system is discussed .
A single - channel independent component analysis method is adopted in the post - processing stage of signal to successfully separate the pulse wave signal . The result shows that the IPPG system has strong practical application ability in the measurement of heart rate signal .

【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN911.23

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