Improve The HHT Method And Its Application In Vibration Signal Processing Of Cable

Signal processing is the crucial issue of monitoring of structure health. Through theprocessing of structure signal, information of structure health can be obtained fromthe signals and the condition of structure health can be diagnosed and evaluated.Aiming at the stable and nonlinear characteristics of the structure monitoring signaland the analysis of its frequency domain when separated, based on the emergingHHT, the following surveys are carried out.（1）Improved EMD of HHT interpolation methods. Reserving the advantagesof self-adaption and modulation, adopting the Kriging fitting technique which givesconsideration to the whole and local precision to improve the overshoot andundershoot brought by the cubic spline of function fitting. The result of the analysisof superposition signal of sine waves shows that the intrinsic mode functiondecomposed by the HHT is more close to the real situation.（2）Improved the endpoint effect. Taking advantage of the prediction functionof Kriging, we can extend the signal, increase the amount of the signal points nearthe endpoint and improve the fitting precision of signal point near the endpoint.Through adding-windows technique, we can lower the weight of the predictingsignal and avoid the prediction error spread to the inside. It shows that the endpointeffect is dramatically improved after being extended and processed byadding-window technique.（3）Inhibition of modal aliasing phenomenon in the HHT analysis method.Discuss the HHT analysis method of modal aliasing problem. Choose commonEEMD method and high frequency harmonic method, five point three times theaverage method and band-pass filtering method for comparison and analysis.Research on the applicability of these four methods in dealing with the interferencesignal. The example shows that the signal after band-pass filter processing, thedecomposition of the intrinsic mode function more accurately, anti-interferenceability, suitable for short and long-interference signal.（4）We combine in time-frequency-amplitude analysis of actual signal.Through cable test, we can measure the signal of accelerated velocity and thenanalyze it with the improved HHT, and know that it has been changed to curve whengetting the cable force of the real situation. Trying to analyses the cablingaccelerated velocity data of the Hedong bridge using the improved HHT, developingthe inner information about the monitoring signal when united, to get the weight andspeed of the car when passing the Hedong bridge.