Noise Identification And Control Of Excavator Cab Based On Blind Source Separation

With the driving comfort of excavators being paid more and more attention,the country has also formulated stricter standards for the noise size of the cab of excavators.In this background,it is necessary to propose a more efficient and convenient scheme of cab noise control.In this paper,the research object is a domestic excavator,and the source of noise near the cab inner ear is analyzed and identified by means of blind source separation,and the corresponding noise control scheme is formulated according to the noise source.Finally,the noise reduction effect of the control scheme is verified.The main work contents are as follows:(1)After analyzing the current research on noise reduction in excavator cabs and the research progress of blind source separation methods,the problem to be solved in cab noise source identification is proposed.Aiming at the difficulty that positive definite blind source separation is not suitable for single-channel signals,the EEMD algorithm is used to increase the dimension of the signal.At the same time,the reasonable parameters of EEMD are determined by the orthogonal test method,which solves the problem that the parameters of EEMD are difficult to determine.Aiming at the difficulty of screening IMF,PCA algorithm is used to reduce the dimension of IMF components and complete the screening;finally,ICA processing is performed to obtain independent components with physical meaning.The above process forms the EEMD-PCA-ICA composite algorithm.(2)The EEMD-PCA-ICA composite algorithm is used to process the collected noise of the right ear of the excavator cab to obtain independent components representing independent noise sources.The time-frequency analysis of these independent components is carried out through S transform to obtain their time and frequency characteristics,and the identification of noise sources is completed by analyzing the characteristics of the spectrogram and the prior experience of the excitation source of the excavator.(3)To solute the problem that the amplitude uncertainty of the independent components is not conducive to the calculation of the subsequent noise source contribution,it is proposed to normalize the components which eliminated the amplitude uncertainty;next,the mixing matrix is deduced through the unmixing matrix of ICA,and then the mixing ratio of the separated components to the source signal is obtained,and the contribution of each independent component to the source signal is quantitatively analyzed.After the cab body-in-white modal test of the test machine,the modal analysis shows that the overall frame of the test excavator cab has good rigidity,but local vibration occurred in the rear panel,roof,right window,etc.(4)Based on the previous theoretical results,the control of excavator cab noise including cab radiated noise,engine noise,and fan noise is carried out.The acoustic package material with better effect is screened out through the porous material experiment,and then the acoustic package layout scheme is determined through the orthogonal test,and finally the optimization of the cab radiated noise is completed.At the same time,the engine noise is optimized for the transmission path of the engine noise,and the fan noise is optimized by changing the fan model.Experiments show that each noise optimization scheme achieves good noise reduction effect.There are 65 figures,22 tables and 66 references...