Unconstrained Physiological Information Monitoring Technology Based On Human Bed Vibration Characteristics

Monitoring the daily physiological information of the family in the state of sleep is an important way to prevent disease in patients with heart and brain diseases or people with potential disease.In daily life,how to obtain real-time physiological information of the human body through convenient detection methods in a state where people don't feel it is a problem that needs to be solved in daily household monitoring.When the heart pumps blood,the force on the support that is in close contact with the human body will change or generate mechanical vibrations,which is called Ballistocardiogram(BCG)signal.The BCG signal monitoring system can extract physiological signals such as human heart activity and breathing status without contacting the human body,which meets the needs of people's long-term real-time health monitoring.In view of this,this paper groundbreakingly analyzes the human-bed system dynamics as the core,carries out research on the BCG signal based on the unconstrained physiological information monitoring method based on the acceleration sensor,and realizes highprecision real-time monitoring of human heart rate in sleep state.The contents are as follows:This study deeply analyzes the mechanism of BCG signal generation,establishes one-degree-of-freedom and two-degree-of-freedom mechanical models for generating BCG signals,and uses the two-degree-of-freedom mechanical model to derive the transfer function of BCG signals.Furtherly,we established the theoretical foundation for human-bed system dynamics analysis.This study pioneered a modal experimental analysis of a human-bed coupled system from the perspective of dynamics analysis.In addition,the modal shapes,frequency response functions and coherence functions of a human-bed system under the three conditions of an empty bed,a bed with a pad,and a bed with a pad and a person in the frequency range of 0 to 150 Hz are analyzed.And obtained the vibration law of human-bed coupling system in this frequency range.Based on this,the optimal direction of BCG signal acquisition was determined to be parallel to the subject's spine;It is further determined that the node position A in the second-and third-order mode shapes is the most advantageous position of the sensor layout.This point can substantially reduce the interference of the high-frequency non-target information on the heart rate information extraction process and improve the monitoring accuracy.Based on the energy peak and the stability of the signal,the correctness of the analysis method was verified by experiments.Using an efficient,low-latency DMA architecture,an unbounded real-time heart rate monitoring system based on Butterworth filter and joint time-frequency distribution algorithm was developed.The simultaneous acquisition and comparison experiments of BCG signals and ECG signals were performed on 15 subjects,and it was concluded that the system has an accuracy of 98.97% and a confidence of 96.07%,which fully verified the real-time and accuracy of the method.This research for the first time analyzed the direction and position of the sensor layout in the signal acquisition process from the fundamental perspective of BCG vibration signal generation,laying a theoretical foundation for the high-accuracy acquisition of BCG signals.And combined with the signal acquisition and processing algorithm,the high-precision real-time heart rate monitoring is realized,which provides theoretical guidance for the application of cardiac shock signals in the monitoring of unbound physiological information.