| With the rapid development of the science technology, enlargement of the industry production, and the increasing of the sorts of the production, the condition in which we use gases as the raw material or fuel is increasing, so that the sorts and the quantity of gas produced are increasing too. Most of these gases such as hydrogen, oxygen, etc are flammable and volatile, and some of them are poisonous. So the air will be polluted if these gases leak out into air during their usage or transportation, and even more it will cause fire, blast or casualty when the condition is very serious. Presently, with the improvement of our life level, coal gas and liquefied petroleum gas (LPG) are widespread as house fuels. Once these gas fuel leak out because the pipeline or valve are not good airproof, it will cause poisoning when the affair is not serious, and terrible fire when serious. All these will bring great damage to the security of our life and possession. So it is very important for us to inspect and control these gases well. And it is obviously very important to study on the inspection methods and sensors of all kinds of gases.Every characteristic parameter of gas sensors must be tested at the beginning of its manufacture and before its leaving factory. The traditional test methods still take dominant place in all test methods. With the development of modern science and technology and development of modern industrial production,and with the increasing testing quantity and the requests for higher testing speed and accuracy, the traditional testing style operated by human is no longer right for modern testing tasks. The virtual instrument technology as a perfect combination of the instrumental technology and computer technology makes a wonderful scheme for testing engineers.As a result of the combination of computer technology and instrument technology,Virtual Instrumentaion technology has broken through old concept of instrument and will become artery of measuring system. The future of virtual instrument have to bond to related IT technology, just like the presence and development of the computer technology increases the invention and application of virtual technology, which exploded a technical revolution in the measuring technology area.In this paper, we study mainly on the semiconductor gas sensitive components, the test system is illustrated at length,including the design of hardware and software structure, mainly the makeup of hardware,and at last supply a set test system composed with the simulation of signal processor, data acquisition, and data analysis and control.The VI automated test system studied by this paper is based on a PC and three data acquisition cards and it is developed with the graphical virtual instruments programming tool LabVIEW8.0,which is produced by NI. The hardware of the system contains the gas sensor test instrument, the DAQ PCI-9111DG card, and a computer. The software of the system contains the sensitivity test, the selectivity test, the stability test, the response and recovery characteristics test. With this developing environment, all the hardware is integrated into a well functioning auto test system. The users just have to make a click with the mouse to send a testing command and the test results will be displayed on the screen very soon. And the voltage signal data of gas sensors to tested gas is saved in text file to be processed. In addition, in order to satisfy user's requirement of processing data, the data text file can be changed into the EXCEL file in which the data processing and data plotting ability are sufficiently used.The functions of virtual gas sensors test system are listed in detail. Finally, this thesis analyses and compares the data acquired by this tests system. The conclusion then can be safely drawn that this system is proved to be successful, while the prospect of this system are provided at the same time. |
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