| Since sleep breathing problems are becoming more and more serious in contemporary society,early diagnosis and treatment are of great clinical significance for disease prevention and control.Sleep breathing monitoring terminals need to measure multiple physiological signals at the same time as the basis for monitoring and diagnosis.Due to different sampling standards of each physiological signal,the logical complexity of signal acquisition task increased exponentially.Therefore,application of RTOS is an inevitable trend for system management and task scheduling.A multi-channel,high reliability and household sleep respiratory monitoring solution was presented in this paper.The specific research contents included four parts:highly integrated terminal hardware design,efficient embedded software system design,user-friendly host computer software design,and prototype system test and analysis.Firstly,the part of terminal hardware took STM32F103VET6 as the main control chip of the system to complete the design of ECG signal acquisition circuit based on ADS1293,blood oxygen signal acquisition circuit based on AFE4490,oronasal flow respiratory signal acquisition circuit based on MIS-2500,thoracoabdominal displacement signal acquisition circuit based on HKH-11 B,as well as power circuit design and storage and transmission module circuit design.Secondly,based on the Free RTOS(Free Real Time Operating System)kernel and referring to the idea of hierarchical design,the embedded software completed the acquisition and driving design of multi-channel physiological signals such as ECG,blood oxygen,oronasal flow,thoracoabdominal displacement in the driver layer.At the application layer,the pulse oxygen calculation model based on Lambert Beer’s law,the improved heart rate algorithm,the primary screening algorithm of sleep apnea and hypopnea events,data storage and online upload were implemented.Thirdly,based on Microsoft Visual C++6.0 MFC(Microsoft Foundation Classes)platform,a simple host computer software was developed to realize the functions of multi-channel physiological signal acquisition,data processing,waveform display and data storage through serials hardware communication and the self-defined data transmission protocol with the terminal.Finally,during the test and analysis of the prototype system,referring to relevant standards,the data acquisition was verified which included two-channels ECG signals,blood oxygen signal,oronasal flow respiratory signal and thoracoabdominal displacement signal.It was also tested that serial port data transmission,power conversion,whole board power consumption and EMC(Electro Magnetic Compatibility)of the prototype.All test results have reached the design expectations.In summary,the scheme of sleep respiratory monitoring system designed in this paper is feasible in principle,and basically realizes the long-term continuous and stable acquisition,transmission and storage of multi-channel physiological signals,which lays a working foundation for the subsequent development of commercial prototype. |
