Development Of Pulse Wave Detection System And Research Of Signal Modeling

Cardiovascular disease with high morbidity and mortality is one of the biggest human health killers since twenty-first Century.Pulse wave is generated in the blood circulation of the cardiovascular system,including the physiological status of the cardiovascular system.Through the accurate detection and analysis of the pulse signal,we can obtain the parameters of blood flow,blood vessel elasticity and vascular obstruction.So it can help clinically diagnose cardiovascular disease.In this paper,the pulse wave detection system is designed to collect the pulse wave,and the hardware and software design of the system is completed.The system is used to collect the pulse wave to evaluate the cardiovascular system and design and optimize the pulse wave blood pressure algorithm.The electric network model of the cardiovascular system is established by the method of parameter analogy to simulate the human pulse wave.The results obtained include the following parts.(1)A pulse wave detection system based on M2 chip is designed.The photoelectric sensor transforms the change of the blood volume of the fingertip into electrical signals,and the signal conditioning circuit is used for amplifying and filtering to eliminate the interference noise and meet the voltage requirements of the A/D conversion.The pulse analog signal is transmitted to the MCU to complete the A/D conversion,by the interface circuit transmitting to the host computer for real-time display and storage,in order to pulse signal for further analysis and processing.The test circuit system is made to collect the pulse wave of different ages.And it can obtain stable pulse signals,which is in accordance with the characteristics of human pulse wave.The pulse data can be processed in MATLAB.(2)This paper presents a method to evaluate the cardiovascular system based on pulse wave.The eigenvalues of the pulse wave and the eigenvalues of the pulse wave,the second derivative and the spectral waveform are extracted.The two parameters that characterize the cardiovascular system are calculated by weighted calculation.The two parameters can be used to establish an index system for assessing the status of the cardiovascular system,which plays an important role in early warning and guidance of health status of human cardiovascular system.Based on the pulse wave detection system,the influence of theposition relation between the sensor and the finger on the pulse wave is studied,and it is found that the sensor placed on the tip of the thumb is beneficial to collecting pulse wave.According to the blood pressure information contained in the pulse wave,the blood pressure measurement algorithm based on the pulse wave is designed.The pulse wave transit time(PWTT)is extracted by fingertip pulse wave,and the regression relationship between blood pressure and pulse conduction time is established.The three segment blood pressure calculation model is proposed to improve the accuracy of blood pressure measurement.(3)The simulation model of pulse wave is established by using parameter analogy method.According to the analogy between physiological parameters and electrical parameters,the heart and arterial dual elastic cavity electrical network model of the cardiovascular system and the state equation of the model equivalent circuit are established.Simulink block diagram is established in MATLAB to simulate the waveform of blood flow of the left ventricle into the aorta and the human pulse wave.The simulation results accord with the characteristics of human physiological pulse wave.Changing the different parameters of the model,I can simulate the pulse wave of human body in different physiological states.The effects of the physiological factors on the pulse wave are studied by comparing the actual pulse wave and the simulated pulse wave.According to the actual phenomenon of pulse wave without dicrotic wave,I adjust the model parameters to simulate the pulse waves in this physiological state.I also simulate the pulse wave of hypertension and calculate its blood pressure by the blood pressure algorithm.And it verify the accuracy of the pulse wave simulation model.The diagnostic method of combined pulse wave detection system and pulse wave simulation model,has important reference and directive value for the diagnosis of cardiovascular disease.