Noise Detection Method And System Of Automobile's Final Drive Based On Virtual Instrument

Noise is one of the most important parameters of automobiles, especially refer to sedans. The direct way to lower automobiles' noise is to reduce its parts'. However, as an important part of automobile's chassis, final drive's character has crucial effect on the whole product.Noise detection of final drive contributes not only to the reduction of automobile's noise, but also to the reduction of production costs. The detection is very useful to discover the problems of the part and solve them before assembly. You can image how waste of time and cost if the problems of the final drive appear just after the whole automobile has been assembled.Based on a practical project, this thesis analyzes the holistic design process of the final drive noise detection system, and then specifies the details of the electronic and virtual instrument system design.Chapter one is the introduction of the thesis. It includes the background and significance of the project, and what had I done during the process.Chapter two is about the foundational knowledge of noise detection. This chapter introduces sound wave and sound field at first, followed by the physical characters and subjective evaluation factors of noise. Physical characters of noise include its frequency, amplitude, etc. The subjective evaluation factors of noise refer to human's subjective feeling of specified noise. However, there do have relations between the physical characters and subjective evaluation factors, but the difference is even much more. This chapter also introduces noise sensors, related instruments, and standards of noise detection issued by our P.R.C. government.The third chapter is the holistic design of the noise detection system. With the method of function analysis, the complicated system can be decomposed into partial functions which can be directly realized.Chapter four is the detailed design of the system. The system is divided into four parts in order to simplify discussion. The four parts are: DAQ sub-system, main towage sub-system, motion control sub-system and load sub-system. This chapter is the detailed design of the four sub-systems.The fifth chapter analyzes the reasons of final drive noise, and introduces some useful signal process methods.Chapter six is the conclusion part of the thesis and also introduces the...