The Research Of The FPGA-Based Data Collection System Of Respirator

Obstructive sleep apnea syndrome (OSAS) is the most common sleep breathes obstacle disease, which is a serious potential threat to the mankind's health. Respirator of continuous positive airway pressure is mostly used to treat OSAS . As respirator has no wounds and has good curative effect to OSAS, CPAP respirator has already become the first-selected method to treat OSAS now. At present respirator can change its performance by changing the software of control system. It is not necessary to changing the hardware and structure of respirator. So This paper designs the air route and the data collection system for respirator.The research on the FPGA-Based data collection system of the respirator combine the advanced technology of mechanics, control theory and digital signal processing together. Following the development trend of the respirator, the system which take advantage of the FPGA which can work at parallel mode and fuzzy PID control theory to design the respirator can bring more stable and comfortable air fluid the patients. The content of this paper is as below:This paper design the air route structure and the control method of the sleep respirator. In terms of the system of respirator is a nonlinear and time-variant control system, the fuzzy control theory was introduced to the control system of the sleep respirator.Base on the characteristics of the sleep respirator design the plan measuring the air flow, the pipe pressure and the pressure of air source. Using the DPF method, which use the Spiro Quant H sensor as the first equipment of the DPF and 163PC01D36 differential sensor as the second equipment for the DPF, to measure the flow of the air. The pressure of the patient's pipe and air source is measure by the differential pressure senor which is produced by Honeywell Company. Base on the measuring plan the paper design the FPGA-Based data collection system, including two parts which are hardware and software. The hardware circuit content is as below :(1) selecting the A/D converter chip and the interface circuit with the FPGA. AD7705 use anΣ-Δconversion technique to realize up to 16 bits of no missing codes performance. The selected input signal is applied to a proprietary, programmable-gain front end based around an analog modulator. The modulator output is processed by an on-chip digital filter. The first notch of this digital filter can be programmed via an on-chip control register, allowing adjustment of the filter cutoff and output update rate. The AD7705 are ideal for use in smart, microcontroller, or DSP-based systems. They feature a serial interface that can be configured for 3-wire operation. Gain settings, signal polarity, and update rate selection can be configured in software using the input serial port. The part contains self-calibration and system calibration options to eliminate gain and offset errors on the part itself or in the system(2) The circuit design of anti aliasing filter.(3) The interface circuit between the D/A converter and the FPGA.(4) The design of the clock and reset circuit of the FPGA. .The circuit of keyboard and alarm.The software design the FPGA-Based the data collection system strictly follow the software design principle and process of FPGA. The software of the system divides into eight parts according to the function of the data collection system. They are as below:(1) The main program module is the main core of the system. The function of the main module is to combine the other module together and use the synthesize tool to optimize the system and fulfill the function of the whole system.(2) The data collection module: the basic function of this module is to initialize the AD7705 and to control this three AD7705 chips and make sure the chips work under the stable condition.(3) The digital filter module: main function of this module is to provide more accurate data by reducing the high- frequency noise signal to the control system of the respirator.(4) The key-input module: main function is to generate the signal that is to control the openness and closure of the control system.(5)The fuzzy control module: main function is to generate the control signal by analyzing the digital data which provide by the data collection module. This module only designed the interface ports.(6) The D/A converter module: main function is to control the work of D/A5600 chip which is to converter the digital control signal to analog signal.(7) The monitoring module: monitor the status of the whole system, deal with unexpected situation happen to the respirator and protect the respirator.(8) The valve control module: main function is to generate the signal which is provided by the air pressure sensor to control the openness and closure of the electromagnetic valve.At last by means of using the synthesize tool to optimize the system and fulfill the function of the whole system, the EDA software automatically translate the HDL program into the hardware circuit .After timing simulation ,the function of the data collection system meet the needs of plan that it take 42us to finish the process and the system clock can run at 89.3MHz.In terms of this data collection system using FPGA, which can implement the parallel works and program in fields that means can update the system more easily, as the MCU, this system can provide more accurate and real-time signal to the control system what makes sleeping respirator more intelligent and effective to the patients. This system plays an important role in the application.