J peaks detection for ballistocardiography based on autocorrelation and dual-threshold

Ballistocardiography (BCG) is a non-contact method of detecting cardiac activity that measures changes in external pressure caused by heartbeats and arterial blood circulation. In this study, BCG signals were collected using a micro-bend fiber sensor along with Electrocardiography (ECG) as a reference signal. A heart rate detection algorithm based on autocorrelation and a dual-threshold J peaks detection algorithm were proposed to achieve real-time detection of heart rates and accurate detection of J peaks. Additionally, signals from six healthy adult subjects were collected to evaluate the effectiveness of the algorithms by comparing the differences between ECG and BCG in heart rate detection and ECG R-peaks and BCG J peaks detection. Results showed that the accuracy of the autocorrelation-based heart rate detection algorithm reached 99.77% and the accuracy of the dual-threshold J peaks detection algorithm reached 98.03%.