A Labview And Laser Doppler Technology Based Micro Displacement Measurement System And Its Applications

With the rapid development of science and manufacture technology, the demand for micro displacement measurement becomes more urgent. In non-contact measure area, the laser Doppler technology, as a dominant method, is an active research topic because it has many advantages such as high precision and real time measurement, etc. On the other hand, virtual instrument technology is widely employed in the testing, measurement and automatic control areas. The advantages of this technology are low development cost, flexible and short development time, etc. Labview is a well-known software for developing virtual instrument. Based on Labview and laser Doppler technology, this thesis focuses on the implementation of a micro displacement measurement system and its application to diesel common rail injector.Firstly, the structure and functions of an injector and the importance of testing items are introduced. Then, according to the product features and system working conditions, the detailed testing requirements are given. The key role of this system is to measure the displacement. Therefore, how to choose an appropriate measure method is of great significance to this system. Chapter 3 introduces several non-contact displacement measure methods and their characteristics. Especially, the laser displacement measurement method is presented. By comparing these measurement methods, the laser Doppler method is chosen as the system displacement measure method. In Chapter 4, the design diagram is established. Chapter 5 is devoted to the design processes of the hardware part and the software part. Some testing results are provided in Chapter 6.Some functions are achieved in this system, such as micro displacement, product current measurement and automatically judging, displaying and recording the test results. The system additionally provides a special mode for monitoring and recording important system or product signal, which is very helpful to analysis system and product. In comparison with contact displacement measurement systems, traditional test equipments and embedded systems, it has several advantages including short test cycle time, kind operator interface, short develop time, low cost, as well as easy maintenance. Another advantage of this system is that only one data acquisition card is used to acquire data and to control the system. In this sense, it further reduces the development cost.