Research On Micro-amplitude Mechanical Vibration Measurement Method Using Video Magnification And Optical Flow Tracking

In engineering practice,the micro-amplitude vibration of mechanical equipment may cause resonance of other parts,so that it is amplified as the main vibration and noise source.In order to avoid the above problems,the micro-amplitude vibration of the mechanical structure must be effectively suppressed,and micro-amplitude vibration measurement is the premise and foundation of micro-amplitude vibration suppression.Additional quality will be introduced and the original dynamic characteristics will be changed since the sensors must be attached on the testing object with the traditional contact measurement method.When measuring micro-amplitude vibration,the negative effect will be further expanded,and lead to severe lower measuring accuracy or can’t even get the measurement result.Meanwhile,there are also some problems,such as low spatial resolution,difficulty in sensor installation,and complexity of detection system.The current commonly used optical non-contact measurement technology make up for the lack of contact measurement.Machine vision vibration measurement has gradually become the most flexible and practical technology in the field of non-contact measurement.However,the existing visual vibration measurement methods mainly aimed at macro vibration measurement,cannot accurately measure micro-amplitude vibration,and thus cannot meet the needs of micro-amplitude vibration measurement.Aiming at this problem,the idea of amplifying vibration signal by video micro-amplitude motion amplification technology and then measuring it by optical flow tracking method is put forward,and the research of micro-amplitude mechanical vibration measurement method using visual magnification and optical flow tracking is studied.The specific work of the dissertation is as follows.Firstly,the existing motion magnification algorithms are studied in the paper and their principles are described.The shortcomings of various methods are analyzed and the two Eulerian motion magnification algorithms are compared.S-transform time-frequency filtering method is studied and a frequency conversion micro-amplitude motion magnification method using S transform is proposed to solve the problem that the filter parameters of phase-based video magnification method are difficult to identify and the frequency conversion micro-amplitude vibration signal cannot be accurately extracted,.Secondly,the basis of the vibration measurement method based on optical flow tracking is studied.Based on the imaging principle of monocular industrial camera and the principle of phase motion amplification,the measuring model of micro-amplitude mechanical vibration is established,and the proportional relation between pixels and spatial size is obtained.The optical flow point matching and tracking algorithm is combined with the frequency conversion micro-amplitude motion magnification method and a micro-amplitude mechanicalvibration measurement method using visual magnification and optical flow tracking is proposed to solve the problem that the existing visual vibration measurement methods cannot perceive and measure micro-amplitude mechanical vibration.Finally,the verification experiment of micro-amplitude mechanical vibration measurement is studied.Taking thin-walled beam as a measuring object,the verification experiment scheme of micro-amplitude mechanical vibration vision measurement using visual magnification and optical flow tracking is proposed and a visual measurement system for micro-amplitude vibration of thin-walled beam is built.The actual amplification effect is analyzed by the fixed-frequency experiment,and the vibration displacement measurement results of thin-walled beams are obtained.The results are compared with the measurement results of single point laser displacement sensor,and the influence of amplification coefficient on the measurement results is analyzed.Finally,the measured results of frequency conversion vibration of characteristic points are obtained by simulation method and compared with theoretical vibration signals.And the error is analyzed.The results show that the method can accurately measure the micro-amplitude mechanical vibration.It provides an effictive and reliable method for micro-amplitude mechanical vibration measurement.