Study On The Instrument Of Landing Gear's Hydraulic System Based On The PXI Bus

As the Virtual Instrument becomes the mainstream technology of test, our country's test technology in aviation area is basically in the stage of intelligent instrument yet. Because the system in the plane becomes more and more complex, the instrument testing the signals of the system need more and more functions with high precision, the intelligent instrument can not meet the need any longer. So in this dissertation the main work is to develop a Virtual Instrument testing the hydraulic system which works for the plane's landing gear .Because of the high performance and the cheap price, the PXI is adopted as the bus of the Virtual Instrument. Through the development we summarize a number of the experience on the Virtual Instrument's development. It can be used for reference when we explore another Virtual Instrument.The main work in the dissertation is included as follows:1. The hardware platform of the Virtual Instrument is built for the test of airplane's landing gear hydraulic system. Through comparing the four structures of the Virtual Instrument, the PXI is chosen to be the bus of airplane's landing gear hydraulic system instrument. Considering the environment the products of National Instrument Co. and the appropriate sensors are chosen to build the instrument to test the signals of the airplane's landing gear hydraulic system.2. Take the case of airplane's landing gear hydraulic system instrument, the software development of the Virtual Instrument is researched. First, the LabVIEW is chosen as the development tool by contrast because of its high efficiency and powerful functions. Second, the software is divided into three parts: Parameter, Data acquisition and Data processing. And the proper ways to realize each part's functions are introduced. Especially using the Event Structure for Dynamically Registering enables that the controls can be moved when the program is running. So, the layout chart of the sensors can be changed according to the test's content. At last, several suggestions are proposed to optimize the performance of the program. They are used in the software of landing gear hydraulic system instrument and they work well.3. The spectral analysis instrument realized through program is used to analyze the pulse of the hydraulic system.4. Analyze the precision of the airplane's landing gear hydraulic system instrument and several ways are taken to reduce the influence of interferences.When the Virtual Instrument works, the data's acquisition, display and analysis prove that the Virtual Instrument really does a good job. The Virtual Instrument with multi-functions can shorten the time for test and analysis on the premise of ensuring the precision.