Research On Laser Doppler Vibration Measurement Technology

In the manufacturing industry,the quality optimization of products plays a vital role in creating economic benefits and increasing GDP.The quality of products requires a comprehensive monitoring system.Efficient,highly automated and stable vibration testing equipment is indispensable during the machining of parts.In order to master and control the vibration,vibration detection must be performed firstly.In this paper,the existing vibration measurement technology is introduced in detail,and the detection method of vibration signal based on laser Doppler vibration measurement technology is selected.Laser Doppler vibration measurement method,as a type of non-contact measurement method,usually uses laser as a medium for measuring vibration.It has high precision and high sensitivity,and can be measured in most environments.Since the manufacture of high-precision laser Doppler vibration measuring equipment at this stage is monopolized by German,American and Japanese companies,it is urgent to realize the localization of high-precision laser Doppler vibration measurement technology and break the foreign monopoly.Subsequently,this paper introduces several optical path structures and measurement principles of laser Doppler vibration measurement technology.The equations of light wave equation and Doppler frequency shift are deduced,and the heterodyne measurement method is selected based on the analysis above.The method has a wide measurement frequency range and fast signal processing speed,and is awidely used in optical path detection.However,in practical applications,due to the existing environmental noise,the measured signal usually has certain interference.The method to deal with the characteristics of the signal to improve the measurement accuracy should be studied emphatically in this paper.In traditional laser Doppler vibration signal processing technology,Fast Fourier Transform(FFT)is used to convert a signal from a-time domain to a-frequency domain to obtain vibration information.However,using this kind of signal processing method can only obtain the approximate value of the vibration frequency,and the error value of the processing result is large.It is difficult to meet the accuracy requirement.To this end,the existing vibration meaturement technology and signal processing technology has been summarized in this paper.and proposing a new signal processing technology suitable for laser Doppler vibration signal-comprehensive correction processing technology.Compared with the signal processing directly using FFT,the proposed algorithm combines time-frequency analysis,spectrum refinement and spectrum correction techniques to improve the calculation accuracy and obtain high resolution under the premise of ensuring signal speed.Vibration information is possible.In this paper,for the working conditions of laser Doppler vibration measurement system,the vibration signal is simulated and analyzed,and the corresponding experimental platform is built.For the high-frequency laser Doppler modulated signal,it is demodulated by orthogonal demodulation method.According to the principle of noise signal generation,RLS adaptive filtering is used to process the vibration signal and improve the signal quality.Finally,according to the actual measured laser Doppler signal,FFT,Z-FFT and ZFFT plus ratio correction method are used respectively to analyze,which makes the calculation accuracy increase by 5~7 times,which proves the demodulation proposed in this paper,the feasibility of filtering and spectrum analysis techniques.