线调频小波路径追踪算法和FrFT相结合的升降速齿轮故障诊断方法

本资料包含pdf文件1个，下载需要1积分

针对升降速阶段齿轮振动信号的非平稳特性,提出线调频小波路径追踪算法和分数阶傅里叶变换（FractionalFouriertransform,FrFT）相结合的齿轮故障诊断方法。该方法采用线调频小波路径追踪算法获得升、降速阶段齿轮振动信号所包含的能量最大信号分量的瞬时频率,并通过对该瞬时频率时频曲线的观察,获得该瞬时频率近似于线性上升或下降的时间范围,提取该时间范围的齿轮振动信号段,用FrFT对所提取的振动信号段进行处理,得到齿轮振动信号段的FrFT频谱图,从FrFT频谱图存在的调制现象来判断齿轮故障。其中FrFT的最佳阶次可由瞬时频率的调频系数计算得到。由于噪声与Chirplet原子的相关性很小,使得线调频小波路径追踪方法对噪声不敏感;另一方面,选择合适的分数阶,信号的FrFT将具有很好的信噪分量效果,因此该方法可用于处理升降速阶段的低信噪比齿轮振动信号。仿真分析和应用实例验证了该方法的有效性和良好的抗噪性。 Due to the non-stationarity of the gear vibration signals measured under the speed-up and speed-down process,a novel fault diagnosis approach based on the combined application of the chirplet path pursuit algorithm and the Fractional Fourier transform（FrFT） method is proposed.With the chirplet path pursuit algorithm,the instantaneous frequency of the signal component whose energy is maximal among all the components in the gear vibration signal is estimated.And then according to the time-frequency curve of the estimated instantaneous frequency,the vibration signal segment whose instantaneous frequency curve approximates as an ascending or descending linear straight line can be intercepted from the original gear vibration signal.By means of the FrFT analysis on the extracted vibration signal segment,the fault of the gear can be detected from the modulation phenomenon which displayed on the FrFT spectrum of the extracted vibration signal segment.In the foregoing process,according to the chirp rate of the instantaneous frequency,the best order of the FrFT method can be figured out.Because of the low correlations between the noise and the chirplet atoms,the chirplet path pursuit algorithm is immune to noise.Furthermore,by selecting a proper fractional order,the good signal-noise separation capability of the FrFT can be achieved.Therefore,the proposed method can be used to process the gear vibration signals with the low signal-to noise ratio which being measured under the speed-up and speed-down process.The validity and the good anti-noise ability of the proposed method are demonstrated by both simulation and practical experiment.