Research On Heart Rate Watch Based On PPG Method

With the improvement of living standards,people pay more attention to health and sports,for the healthy development of wearable devices to provide a driving force,the domestic healthy wearable devices have also developed rapidly.But the rapid launch of the product is always accompanied by a variety of problems:inconvenience,lack of endurance,inaccurate measurement data,etc..The chest with a heart rate watch or bracelet heart rate recently there are more problems.The method of measuring heart rate watch or bracelet are light plethysmography(Photo-Plethysmo-Graphy,PPG),which is a method of optical detection rate,it is very convenient to use,but to improve the accuracy of heart rate is very difficult.The goal of this project is to develop a user-friendly intelligent heart rate watch,with low power Bluetooth(Bluetooth Low Energy,BLE)communication function and supporting the Android application software,long life time and high accuracy rate acquisition functions.To achieve the above objectives,the first analysis of the causes of heart rate measurement based on the principle of PPG watch is not easy to improve the accuracy of.Baseline drift,multiple peaks,Gauss white noise,individual differences,human movement,environmental light interference will cause heart rate measurement difficulties.In addition,from the aspects of function and hardware and software,the reasons of high power consumption and BLE communication instability are analyzed in detail.Based on this,the following research programs and the following research and work.The wavelet theory is studied deeply and the Mallat fast algorithm is implemented in real-time embedded system with C language.On this basis,continue to study the application of wavelet filtering,the heart rate signal wavelet filtering and heart rate extraction.The embedded program design and scheduling algorithm,real-time operating system(Real Time Operate System,RTOS)and BLE protocol and protocol stack are studied in detail,and the TI-RTOS and BLE protocol is designed based on the scheduling algorithm of software architecture and the top.In addition,the hardware selection and design,and made a four layer PCB board.Finally,based on the Android system application software written in conjunction with heart rate watch.The development of the intelligent heart rate watch with calendar clock,pedometer,heart rate detection,power failure data storage,user interaction,BLE communications and other functions.The measurement error is within 10%,the static heart rate error is less than 5%,and the dynamic heart rate error is less than 10%.Heart rate watch BLE communication stability,life time can reach more than a week in normal use and standby condition,can achieve 12.5 hours of heart rate measurement situations.With BLE communication,heart rate display and heart rate curve,pedometer,sedentary reminder function and application software of smart watches with heart rate.