Research On The Techniques Of Dynamic Heart Rate Measurement Based On Seismocardiography

Cardiovascular disease is usually caused by abnormal heart function or abnormal blood circulation system,and its mortality rate has been increasing year by year in the past30 years,which is a serious threat to human life and health.Therefore,the management of heart health in daily life,especially the continuous monitoring of heart rate,plays an important role in improving the accuracy of cardiovascular disease prediction or even preventing sudden cardiovascular disease.In the current researches,the multi-sensor measurement system has insufficient performance in multiple dynamic scenarios and the measurement scheme is complex,while the single-sensor measurement system needs to preset algorithm parameters,which are difficult to meet the needs of dynamic heart rate measurement in daily life.In order to achieve convenient,real-time and accurate dynamic heart rate measurement,this paper uses the seismocardiography(SCG)as the heart rate measurement method,and focuses on simplifying the measurement scheme and improving the measurement accuracy of multiple dynamic scenarios.The motion interference signal modeling and single-channel dynamic heartbeat signal separation algorithm are studied.And then the algorithm was applied on the dynamic heart rate measurement system.The main research contents are describrd as follows:Firstly,the measurement methods and techniques of dynamic heart rate measurement at home and abroad are analyzed in detail.The heart rate measurement method is based on the heartbeat signal,and the physiological principle of the heartbeat signal is introduced in detail.An AO peak recognition algorithm based on multi-features of the heart shock signal is proposed and the error analysis of the recursive least square signal separation algorithm is carried out,which provides a theoretical basis for the design of the dynamic heart shock signal separation algorithm and the calculation of dynamic heart rate.Secondly,a unified autoregressive model is established for motion artifact signals.The time-frequency characteristics of SCG and various dynamic interference signals are systematically analyzed,and the time-varying autoregressive model is used to uniformly model the motion artifact signals,which solves the problem that the signal separation algorithm needs to preset parameters for different dynamic scenarios.Thirdly,a single-channel dynamic SCG separation algorithm is proposed.A linear filter is used to model a single-channel observation signal,which overcomes the defect of insufficient observation signals in the single-channel blind source signal separation algorithm.The adaptive forgetting factor filter is designed based on the posterior error model,which improves the signal-to-noise ratio and peak measurement accuracy of signal separation in the case of multi-motion interference.The simulation and measurement results show that the signal-to-noise ratio of the separated signals in the standing,walking,running and jumping scenes is increased by 8.5%,10.2%,45.0% and 67.3% respectively,the AO peak detection accuracy reaches 99.4%,98.3%,97.5% and 97.1% respectively.Finally,a dynamic heart rate measurement system based on SCG is designed.The system only integrates an accelerometer for sensor data measurement,which greatly simplifies the measurement scheme.The proposed single-channel dynamic SCG separation algorithm was emdeded in the designed system,which realizes convenient,real-time and accurate dynamic heart rate measurement.The experimental results of multiple dynamic scenarios show that the dynamic heart rate measurement system has a 95% confidence interval of heart rate within ±2.0 BPM in warm-up exercises,indoor running,spinning and free exercise scenarios.And the linear correlation coefficient of heart rate and the goodness of fit are both as high as 0.99.At the same time,from the three indicators of heart rate 95%confidence interval,heart rate linear correlation coefficient and heart rate linear fit,in the four dynamic scenarios,the performance of the dynamic heart rate measurement system is better than the newly released Xiaomi sports watch.