Design And Implementation Of Sleep Monitoring System Based On Piezoelectric Film Sensor

Good sleep can enhance human immunity,eliminate fatigue,promote physical recovery and protect the central nervous system.ballistocardiogram(BCG)signal is an important signal to judge whether the heart is in normal state during sleep.This paper focuses on the separation and extraction of physiological characteristic parameters of heartbeat and respiration during sleep,uses piezoelectric film PVDF sensor as monitoring means,designs and implements signal conditioning circuit,studies the signal processing method based on BCG signal,and realizes the monitoring function of physiological parameters of heartbeat and respiration.The main work of this paper is as follows:1.The BCG signal characteristics were analyzed,and the charge amplifying circuit,pre-amplifying circuit and low-pass filtering circuit were designed and implemented.The high precision AD conversion chip and processor were used to realize the digital signal acquisition function,and the communication function between WIFI and the upper computer was realized,and then the cardiac shock signal monitoring system based on the piezoelectric film PVDF sensor was constructed.2.Aiming at the problem of effectively extracting breathing and heartbeat signals from BCG signals,a Improved whale optimization algorithm based on the improved whale Optimization algorithm was proposed.IWOA(Variational Mode Decomposition)optimization method.Firstly,physiological signals were preprocessed,and the ratio of sample entropy and energy difference was used as the fitness function of the improved whale optimization algorithm to optimize the penalty factor α and the number of decomposition layers K in variational mode decomposition.Then the signals are decomposed into multiple Mode Functions(IMF);Finally,the effective component was selected by the double threshold method.Meanwhile,it is compared with Empirical Mode Decomposition(EMD)and Ensemble Empirical Mode Decomposition(EEMD).The results show that the IWOA-VMD method is effective in alleviating the mode aliasing and boundary effect problems in the decomposition process and has a good reconstruction effect.3.In view of the reconstructed signals from the three methods,the differential threshold peak search method and Fast Fourier Transformation(FFT)are used to calculate the heart rate and breathing rate respectively.Compared with the experimental results of EMD and EEMD,the mean error of respiration rate obtained by IWOA-VMD algorithm is 0.097 and 0.013 lower than that of EMD and EEMD,and the mean error of heart rate is 0.03 and 0.006 lower than that of EMD and EEMD,respectively.The results show that the proposed method has better accuracy.4.The sleep monitoring system is developed,the system software is written,the display interface based on MATLAB is designed,the data acquisition and analysis function is realized,and the correctness of the design circuit and the proposed method is verified.Figure [56] Table [2] Reference [66]...