The Software Design Of Vibration Signal Pretreatment For Helicopter Fault Diagnosis

Helicopter has an irreplaceable position in the modern war due to its flexible mode. With the improvement of people’s living standard, the helicopter is used as a special means of transport in the emergency rescue, medical treatment, rescue rescue,traffic monitoring, forest fire and other aspects. At the same time, more and more people pay attention to the problem of helicopter safety. Many countries research the system of helicopter fault diagnosis online or offline to reduce the avoidance of mechanical accidents. The acquisition and pretreatment of vibration components and related signal is the basis of helicopter fault diagnosis. The pretreatment of the original signal will reduce noise and interference, providing the basis for the acquisition and accurate characteristics of fault diagnosis. For the vibration signal characteristics of helicopter, this topic studies the pretreatment method of vibration signal for helicopter fault diagnosis and realizes the vibration signal pretreatment, laying the foundation for the further development of system of helicopters fault diagnosis.This thesis analyzs the common synchronous averag technique and the principle of wavelet transform in the vibration signal pretreatment according to the characteristics of the helicopter vibration signal. And then the synchronous averag technique and wavelet transform are ulilized in denoising, focusing on the option of wavelet and threshold function when the technique of wavelet transform applying to denoise. On the basis of this, the simulation experiments of feasibility and effectiveness of the proposed algorithm are verified by MATLAB. Considering this issue to be in the particular hardware environment to achieve effective acquisition of vibration signal pretreatment, this paper briefly introduces the hardware circuit structure of helicopter bearing fault analyzer and working principle, including DSP system, signal conditioning circuit, A/D conversion circuit, PCI communication interface, PC/104 module. And then, the design and realization of the software of the vibration signal pretreatment in the helicopter fault diagnosis are described in detail.The software includes a PCI interface drive, API interface function design, and storage and reading of the raw data, the pretreatment of original sampling data by using multi-cycle synchronous averag and wavelet transform. Finally, the data display is output. The development and implementation of software is realized in the PC/104 platform using C++6.0 Visual programming.Finally, the design of the software combines with the hardware of helicopter bearing fault analyzer to accomplish the test and experiment, verifying the effectiveness of the design of the noise elimination algorithm and the correctness of the software program. The synchronous averag technique and the wavelet transform technology had obvious effect on the denoising of the vibration signal as the experimen results show. The software design has the function of managing the hardware of the analysis instrument and the pretreatment of the collected vibration signals. It provides the basic conditions for the next development of the fault analysis and diagnosis system for the helicopter bearing.