| With the rapid development of modern engineering technology, it is of great significance to measure the speed of the moving objects with high precision and fast measurement, such as fluid flow, vehicle speed.The photoelectric measuring system has the characteristics of non-contact, real time and high precision, and has become an important development direction of the speed measurement technology. From the point of practical application, photoelectric velocity measurement system is used to measure solid motion velocity and fluid velocity, focusing on the photoelectric signal processing method.This thesis starts from the background and significance of the photoelectric tachometer, then several photoelectric measurement methods are introduced and compared. Finally, the signal processing methods of fluid velocity measurement and solid motion velocity measurement are studied.In the system design of fluid velocity measurement, based on the principle of laser Doppler velocity measurement, the double beam-double scattering light pattern is adopted to analyze the collected Doppler signal. Through fast Fourier transform, the Doppler shift can be obtained accurately; In order to reflect the real-time change of the flow velocity, the signal is processed by short-time Fourier transform.In the system design of solid motion velocity measurement, two related scattering signal can be obtained by using dual-beam scattering light pattern. Through the relevant algorithms to process the scattered signal, the delay time of the two signals can be measured quickly and accurately. In addition, by studying the problem of the maximum delay time, it is concluded that the delay time can not exceed two-thirds of the total sampling time. |
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