Research Of Mechanical Vibration Signal De-nosing Based On Wavelet Transform And DSP Implementation

Analysis and processing of vibration signals are the main methods to realize mechanical fault diagnosis. However, in actual gathering process, because of the data acquisition environment and instrument, the vibration signal is interfered by noise inevitably, influencing signal analysis and processing in the following stage. Therefore, the acquisition and processing of vibration signals have practical significance. In this thesis, vibration signals of rotating machinery are studied primarily using wavelet transform. On this basis, a de-noising algorithm based on lifting wavelet transform is presented, and a platform of vibration signal acquisition and processing based on digital signal processor is developed.Firstly, mechanical equipment fault types and vibration signals characteristics are analyzed, and the basic theory of wavelet transform is introduced. According to multiresolution analysis, experiments on representative rub-impact signal are performed. The results show that position and time of the fault can be pinpointed using wavelet transform.Then the lifting wavelet scheme is presented, compared with the traditional wavelet, the lifting scheme has many advantages such as fast calculation and in-place operation, making it suitable for real time system application. In order to find out the best parameter combination for wavelet de-noising, a large amount of simulation is carried out, some rules of choosing parameters are summarized by comparing the simulation results, and the wavelet parameters for rub-impact signal de-noising are determined.At last, the establish of hardware platform and implement of de-noising algorithm are introduced. The platform, with a core of TMS320VC5509 from TI Company, realizes fast de-noising algorithm based on lifting wavelet scheme, which consists of four modules, that are data gathering, data processing, data transmission and man-machine interface. By system debugging and field test, it is shown that the system works well and the results are satisfying.