Automatic Pressure Regulating Noninvasive Ventilator Developed

Breathing machine as a widely used clinical auxiliary or replace the normal breathing in patients with medical devices.According to the object-oriented classification,the breathing machine can be divided into household medical breathing machine and breathing machine. This article mainly discuss the household breathing machine developed based on ARM embedded. Its main use is the spontaneous breathing, but breathing is not smooth.According to the patients of spontaneous breathing, breathing machine outs put pressure, and assists patients breathe, often used in the treatment of snoring.According to design requirements, the paper designs the whole control scheme, including the hardware control circuit and software control scheme.In terms of hardware as the main control chip,we choose LPC2387. through an advanced integrated MPXV5004G silicon pressure sensor,it can realize the pressure real-time monitoring. Fan control by Motorola company special brushless dc motor control chip MC33035and MC33039constitute a closed-loop control of the fan speed measuring device, ensure that the fan control effect.Through the LCD display and keyboard operation,the type shows ways using a3.2inch TFT LCD display module,and its display is exquisite,which to help the user configuration breathing machine related parameters, observing breathing machine running pressure curve in real time.Through the operating system platform,in the aspect of software control,it transplants the embedded real-time operating system μC/OS-ii, creating three different priority task.The task form is given priority to control tasks, human interface, respectively, and the upper machine cocmunication tasks. After operating system transplant, developers can task oriented progracming,which can not only improve the efficiency of development, but also for subsequent upgrade is also helpful.On man-machine synchronization realization,this paperdiscusses several cocmon switching methods. In this design, it uses the hybrid switching method, through the calculation of pressure change rate,combined with fixed respiration action time to implement the motor,it makes an adjustment with the patient breathing movements. The experimental test results show that, the ventilator can be achieved according to patients’respiratory movement, and automatically adjust the output value of different pressure, the man-machine synchronization is good. The pressure regulation scope reach0-4000Pa, when the set press is less than2000Pa, running noise is less than60decibels, meet the design requirements for the function and parameters in the index.