Analysis of Vibration and Acoustic Signals for Noncontact Measurement of Engine Rotation Speed The noncontact measurement of engine speed can be realized by analyzing engine vibration frequency. However, the vibration signal is distorted by harmonics and noise in the measurement. This paper presents a novel method for the measurement of engine rotation speed by using the crosscorrelation of vibration and acoustic signals. This method can enhance the same frequency components in engine vibration and acoustic signal. After crosscorrelation processing, the energy centrobaric correction method is applied to estimate the accurate frequency of the enginexe2x80x99s vibration. This method can be implemented with a lowcost embedded system estimating the crosscorrelation. Test results showed that this method outperformed the traditional vibrationbased measurement method.

A study on rotate vector reducer performance degradation based on acoustic emission techniques This paper presents a performance degradation analysis for rotate vector (RV) reducer using acoustic emission (AE) techniques. Unlike the AE signals from fixed gear reducer that are steady and have unchanged route, the AE signals from RV reducer have variant propagation paths and strengths. This work investigates the kinematics model using AE techniques to solve the inherent issues of RV reducer performance degradation analysis, such as signal variabilities and inappropriate thresholds. Firstly, the propagation path of AE signals within the crankshaft is developed. Secondly, the attenuation trend of AE signals is exponentially formulated based on the corresponding propagation curve. The proposed method has been evaluated on the developed RV reducer platform. AE signals were collected under various working conditions, i.e., four abrasion states with eight types of loads and five rotation speeds. The experimental analysis on typical parameters (e.g., signal energies) proves the effectiveness and accuracy of the developed method based on AE techniques.