Tian Haochen, Zhao Haiwen, Guo Shijie, Liu Jinyue, Wang Xuzhi
School of Mechanical Engineering and Hebei Key Laboratory of Robot Sensing and Human-robot Interaction, Hebei University of Technology, Tianjin 300130, P.R.China.
School of Mechanical Engineering and Hebei Key Laboratory of Robot Sensing and Human-robot Interaction, Hebei University of Technology, Tianjin 300130,
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2019 Apr 25;36(2):281-290. doi: 10.7507/1001-5515.201707002.
The requirement for unconstrained monitoring of heartbeat during sleep is increasing, but the current detection devices can not meet the requirements of convenience and accuracy. This study designed an unconstrained ballistocardiogram (BCG) detection system using acceleration sensor and developed a heart rate extraction algorithm. BCG is a directional signal which is stronger and less affected by respiratory movements along spine direction than in other directions. In order to measure the BCG signal along spine direction during sleep, a 3-axis acceleration sensor was fixed on the bed to collect the vibration signals caused by heartbeat. An approximate frequency range was firstly assumed by frequency analysis to the BCG signals and segmental filtering was conducted to the original vibration signals within the frequency range. Secondly, to identify the true BCG waveform, the accurate frequency band was obtained by comparison with the theoretical waveform. The J waves were detected by BCG energy waveform and an adaptive threshold method was proposed to extract heart rates by using the information of both amplitude and period. The accuracy and robustness of the BCG detection system proposed and the algorithm developed in this study were confirmed by comparison with electrocardiogram (ECG). The test results of 30 subjects showed a high average accuracy of 99.21% to demonstrate the feasibility of the unconstrained BCG detection method based on vibration acceleration.
睡眠期间对心跳进行无约束监测的需求日益增加，但目前的检测设备无法满足便利性和准确性的要求。本研究设计了一种使用加速度传感器的无约束心冲击图（BCG）检测系统，并开发了一种心率提取算法。BCG是一种定向信号，沿脊柱方向比在其他方向上更强，且受呼吸运动的影响更小。为了在睡眠期间测量沿脊柱方向的BCG信号，将一个三轴加速度传感器固定在床上，以收集由心跳引起的振动信号。首先通过对BCG信号进行频率分析假设一个近似频率范围，并对该频率范围内的原始振动信号进行分段滤波。其次，为了识别真实的BCG波形，通过与理论波形比较获得准确的频带。通过BCG能量波形检测J波，并提出一种自适应阈值方法，利用幅度和周期信息提取心率。通过与心电图（ECG）比较，证实了本研究提出的BCG检测系统和开发的算法的准确性和鲁棒性。30名受试者的测试结果显示平均准确率高达99.21%，证明了基于振动加速度的无约束BCG检测方法的可行性。
