Research For Fuzzy PID Control System Applied For Non-invasive Continuous Blood Pressure Measurement

At present, high blood pressure has become the most common cardiovascular disease inthe world，which has been a big threat to the health of human beings. Taken accuratemeasurement of blood pressure, which is a help to early detection and identification of thetype of high blood pressure，which has very important significance to find a reasonabletreatment recommendations for the prevention and treatment of hypertension. Meanwhile, theblood pressure is an important physiological indicator of the body, which can reflect theimportant physiological parameters of the human heart and the functional status of bloodvessels, and the important parameter of circulatory system of human, and which is also theimportant basis for clinical diagnosis of disease, the observed treatment effect and thejudgement of prognosis.The human blood changes with the menstrual cycle, emotion,and thevarious external and internal stimuli, with significant volatility. And with the influence of thephysical conditions of blood pressure parameters,the environmental conditions andphysiological laws and many other factors,there are big errors in the result of a singlemeasurement or intermittent measurements.The continuous measurement method canmeasure blood pressure at each cardiac cycle,so which has more significance in the clinicaland medical research. The existing measurement test equipment of non-invasive continuousblood pressure is very complex, which needs high positioning of the sensor, which is notsuitable for long period of continuous blood pressure monitoring, so a new continuous bloodpressure measurement must be found.In this paper, we propose a non-invasive continuous blood pressure measurementmethods based on the vascular unloading technique, and build a non-invasive continuousblood pressure measurement system on the basis.In the open-loop state of the system, theno-load state of the measurement of blood pressure is extracted, with the applications ofoscillometric method, which is the reference blood pressure status of the closed-loop state ofthe system. In the closed-loop state of the system, with the use of vascular unloadingtechnique and negative feedback control, the tendency of the blood vessels is controlled andmaintained no-load state.The continuous measurement of the external servo pressure is thecontinuous arterial blood pressure.In this paper, the set up work of the non-invasive continuous blood pressure measurementsystem can be divided into two parts: the hypogynous-machine control and the optimizationof the PC control. The design of the hypogynous-machine control includes the set up of the pump, solenoid valve, air bag, pressure sensors, oxygen sensor, vascular volume waveacquisition board and other structures. And take the real-time acquisition optical signal as thenegative feedback signal of the system,with the real-time changed PWM signal generated bythe DSP development board,the speed of the pump and the opening degree of the solenoidvalve are controlled,then the real-time acquisition of the pressure signal is achieved; With theuse of fuzzy-PID control to optimize the control parameters of the system,the optimization ofthe PC control is achieved.So the obtained continuous blood pressure can meet the requiredprecision and the high accuracy of continuous blood pressure measurement is achieved.The Experimental results show that the continuous non-invasive blood pressuremeasurement method proposed in the paper is feasible, and the non-invasive continuous bloodpressure measurement system has good reliability.