非抽样多小波和Hilbert-Huang时频分析在行星减速器早期故障诊断中的应用

Undecimated Multiwavelet and Hilbert-Huang Time-frequency Analysis and Its Application in the Incipient Fault Diagnosis of Planetary Gearboxes

提出一种改进相邻系数方法和非抽样多小波变换融合的降噪方法,使用Hilbert-Huang时频分析作后处理,并将其应用于行星减速器早期故障诊断中。行星减速器具有故障响应微弱、振动的强烈非平稳性和明显的非线性、低频特征频率污染等特点,使得现有中心轴固定的传统齿轮箱诊断理论与技术不能有效解决行星减速器的故障诊断难题。非抽样多小波变换具有时间平移不变性,可以降低或消除信号中奇异点附近急剧振荡的Gibbs现象;改进相邻系数方法具有随分解层变化的邻域区间长度和灵活的阈值选取方式,能够准确提取出非平稳信号中的早期微弱故障特征信息;Hilbert-Huang时频分析可以更直观地表征信号中的非平稳、非线性特征。对实际信号的分析结果表明,该方法可以准确提取出行星减速器存在早期齿面点蚀损伤时的微弱故障特征。

A denoising method of the improved neighboring coefficients and the undecimated multiwavelet transform is proposed, Hilbert-Huang time-frequency analysis is applied as the post-processing method. The proposed method is applied to the incipient fault diagnosis of planetary gearboxes. In the planetary gearbox, the fault response is quite weak; the vibration is obviously non-stationary and evidently nonlinear; low-frequency characteristics are easily immersed in heavy noise. Therefore, the existing fault diagnosis theory and technology for traditional fixed-shaft gearboxes fail to solve the difficulty in the planetary gearbox fault diagnosis. The undecimated multiwavelet transform has the shift-invariant property in time domain, which can effectively weaken the Gibbs phenomena in the neighborhood of the discontinuities. The improved neighboring coefficients can select variant sizes of neighboring window and flexible thresholds at different decomposition levels, which can correctly extract the incipient fault features in the non-stationary signals. Hilbert-Huang time-frequency analysis can intuitively represent the non-stationary and nonlinear features of the collected signals. Experiments indicate that the proposed method can correctly extract the weak fault features caused by the incipient pitting defects in the planetary gearbox.