醫(yī)用超聲流量計標定氣體流量控制系統(tǒng)的設計

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摘要 隨著科學技術的進步和工業(yè)的發(fā)展,工程中對氣體流量的控制及測量精度的要求越來越高。但由于氣體的可壓縮性遠大于液體的可壓縮性,氣體流量控制更是難以精確控制。傳統(tǒng)流量控制是通過改變流量控制閥的閥內流道的最小截面積,從而改變流動阻力的辦法來實現(xiàn)的。理論上,改變節(jié)流通道的面積,可線性調節(jié)流量。流量不只和節(jié)流面積有關,實際上,節(jié)流面積的改變,也必然會使閥前后的壓差發(fā)生變化。這就導致相對開度和相對流量之間的關系是不一定的,非線性的。通過調節(jié)閥芯開度的方式來調節(jié)流量雖然不夠精確,而且不易實現(xiàn)自動化控制[1]。但在實際應用中,有時需要在一個系統(tǒng)中對流量實現(xiàn)自動化控制。針對這種情況,構建了一個氣體流量控制系統(tǒng)系統(tǒng)。氣體流量控制系統(tǒng)的設計，可用于系統(tǒng)中流量的自動控制。
本課題完成了基于msp430單片機、IAR EWARM的總體方案和組成框架設計、硬件和軟件的設計，用于控制步進電機進而控制閥門工作。用戶通過用戶操作界面設定氣體流量控制裝置的各項參數(shù)，來實現(xiàn)想要的氣體流量速度。氣體流量自動化控制系統(tǒng)設計使得用戶使用起來更加簡便、直觀。
硬件電路主要包括信號的采集、單片機控制模塊。信號采集電路主要完成信號采集，放大，濾波功能，屬于典型的信號采集處理系統(tǒng)。處理對象，根據(jù)超聲流量計信號的特點，設計了前置放大電路。為更好的降低干擾的影響，設計了高通和低通濾波電路，成功提取了超聲流量計信號。微控制器電路通過A/D轉換把模擬信號轉換成數(shù)字信號送至微處理器做進一步處理。
軟件部分主要完成超聲流量計信號存儲和處理等功能，開發(fā)工具是IAR，采用C語言來編程。主程序通過調用各種子程序模塊完成特定的功能。子程序包括數(shù)據(jù)采集處理、步進電機正反轉子程序、加速程序。

關鍵詞：氣體流量 控制系統(tǒng) 信號采集 步進電機

The design of the control system using the medical ultrasonic flowmeter to calibrate gas flow
Abstract With the development of science and technique progress and industry, control and measurement accuracy of the gas flow in the project of the increasingly high demand. But due to the compressibility of gas is far greater than the compressibility of the liquid, gas flow control is even more difficult to precisely control. The control of traditional traffic is the minimum cross-sectional area to change the flow control valve of the valve flow, thus changing the flow resistance of the approach to the realization of the. In theory, change the throttle channel area, linear flow regulation. Flow not only,and the throttling area in fact, throttle area change, will also make the pressure valve before and after the change. This leads to the relationship of between relative opening and the relative flow is not necessarily, nonlinear.By adjusting the valve opening to regulate the flow though the way is not precise enough, and not easy to bring about auto-control. But in practical application, sometimes need in a system to bring about the automatic control of flow. In view of this situation, to build a system that can control the gas-flow . The design of gas-flow control system, can be used for automatic control system of flow.
This paper completes the overall plan of msp430 SCM, IAREWARM and the frame design, the design of hardware and software based on, for control of stepper motor and control valve. The user set parameters of gas-flow control device through the user interface, to achieve the gas-flow velocity wanted. The gas-flow automatic control system allows users to use more convenient, intuitive.
The hardware circuit mainly includes signal acquisition, MCU control module. The circuit of signal acquisition mainly completes signal acquisition, amplification, filtering function,which belongs to the typical signal acquisition and processing system. The treatment object, according to the characteristics of ultrasonic flowmeter signal, design the pre amplifier circuit. In order to reduce the interference effects,designing a wave filter of high and low pass, successfully extracted from ultrasonic flowmeter signal. The circuit of micro controller through the A/D converter converts the analog signal into digital signal is send to the microprocessor to further processing.
The software part mainly completes the signal storage of ultrasonic flowmeter and processing functions, development tools are IAR, using C language programming. Main program completed a variety of specific functions by calling the subroutine modules. Subroutine includes data acquisition and processing, man-machine interface program of stepper-motor and rotor program.

Keywords: gas-flow rate Control system signal acquisition stepper motor

目錄
第一章緒論 1
1.1課題研究的背景和意義 1
1.2國內外研究現(xiàn)狀和發(fā)展 1
1.3本文的工作目標及內容 4
1.3.1本文主要工作 4
1.3.2論文結構安排 4
第二章系統(tǒng)總體分析 5
2.1系統(tǒng)方案論證 5
2.2系統(tǒng)總體結構設計 5
第三章硬件設計 6
3.1步進電機分析 6
3.1.1步進電機優(yōu)點 6
3.1.2步進電機缺點 6
3.1.3步進電機原理與機理 7
3.2單片機系統(tǒng) 9
3.2.1單片機定義 9
3.2.2單片機特點 9
3.2.3單片機選擇 9
3.3信號采集模塊 11
3.3.1信號檢測與傳感器 11
3.3.2前置放大電路 12-b..