This article presents an automated procedure for acquisition and analysis of BallistoCardioGraphy (BCG) traces. A triaxial accelerometer and a microcontroller unit are used to record heart-induced recoil forces generated from a lying subject. The problem of BCG J-peak annotation is split into two subtasks: candidates extraction, based on a detection signal, and actual annotation, guided by subject-specific search windows. Such a procedure is derived from an automatic calibration, which is carried out with no need of concurrent ElectroCardioGram (ECG) or user intervention. The algorithm also implements postannotation checks for refinement of annotation, which effectively reduces the number of missed J-peaks. The impact of each algorithm phase is analyzed, assessing statistical significance of each step; finally, performance is optimized in a data-driven fashion. Results show that the proposed methodology is able to achieve high sensitivity and precision (the median score is 98.9% and 98.1%, respectively) in J-peak detection. The quality of J-peaks timing annotation is further demonstrated by a very low discrepancy between BCG and ECG heart rate (HR) estimates. Overall population, the standard deviation of such error was found to be approximately 6.56 ms, whereas the mean absolute error was just 4.7 ms (i.e., ≈ 1.18; Ts, where Ts = 4 ms is the sampling period). Such scores, indeed, improve over recent related literature.

中文翻译：

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对心冲击图加速度计迹线进行准确的心跳检测

本文介绍了用于采集和分析 BallistoCardioGraphy (BCG) 迹线的自动化程序。三轴加速度计和微控制器单元用于记录躺着的受试者产生的心脏诱发的反冲力。BCG J-peak 注释的问题分为两个子任务：基于检测信号的候选提取和由特定主题搜索窗口引导的实际注释。此类程序源自自动校准，无需并发心电图 (ECG) 或用户干预即可执行。该算法还实现了注释后检查以改进注释，从而有效地减少了遗漏 J 峰的数量。分析每个算法阶段的影响，评估每个步骤的统计显着性；最后，性能以数据驱动的方式进行了优化。结果表明，所提出的方法能够在 J 峰检测中实现高灵敏度和精确度（中位数分别为 98.9% 和 98.1%）。BCG 和 ECG 心率 (HR) 估计值之间的极低差异进一步证明了 J 峰值时序注释的质量。总体而言，发现这种误差的标准偏差约为 6.56 毫秒，而平均绝对误差仅为 4.7 毫秒（即 ≈ 1.18；Ts，其中 Ts = 4 毫秒是采样周期）。这样的分数确实比最近的相关文献有所提高。BCG 和 ECG 心率 (HR) 估计值之间的极低差异进一步证明了 J 峰值时序注释的质量。总体而言，发现这种误差的标准偏差约为 6.56 毫秒，而平均绝对误差仅为 4.7 毫秒（即 ≈ 1.18；Ts，其中 Ts = 4 毫秒是采样周期）。这样的分数确实比最近的相关文献有所提高。BCG 和 ECG 心率 (HR) 估计值之间的极低差异进一步证明了 J 峰值时序注释的质量。总体而言，发现这种误差的标准偏差约为 6.56 毫秒，而平均绝对误差仅为 4.7 毫秒（即 ≈ 1.18；Ts，其中 Ts = 4 毫秒是采样周期）。这样的分数确实比最近的相关文献有所提高。