变工况下旋转机械故障跟踪的相空间曲变方法

Fault tracking of rotating machinery under variable operation based on phase space warping

为实现在工况变化条件下对旋转机械的故障预测,提出使用相空间曲变和平滑正交分解理论在变工况条件下跟踪旋转机械的故障演化过程.首先在对目标系统的观测时间序列相空间重构的基础上,通过量化相空间曲变构建信号损伤演化的跟踪函数,为弥补累积模型误差和相空间点局部分布概率差异造成的误差,将时间序列和相空间进行分割,并以此构建跟踪矩阵;再利用平滑正交分解方法将跟踪矩阵中分别由实际损伤劣化和工况变化造成的演化趋势进行分离,根据平滑正交特征值提取出其中能够反映实际故障演化趋势的平滑正交分量;最后以变转速情况下轴承外环故障退化的仿真信号为例验证算法的有效性.计算结果表明:本文提出的算法能够对旋转机械故障的演化趋势实现有效跟踪,基本排除转速波动造成的工况变化影响.

For fault prognosis of rotating machinery under variable operation, a fault tracking method based on phase space warping and smooth orthogonal decomposition （SOD） is presented to describe the degradation process of rotating machinery. Firstly, phase space is reconstructed using vibration time-series, and a tracking function of damage evolution is built by quantifying phase space warping. To compensate for cumulative model error and the error caused by variation of local probability distribution of the reference phase spacepoints, the original time-series is partitioned into several data segments and the phase space is partitioned into several subspaces correspondingly. Several feature vectors are concatenated into tracking matrix. Secondly, the different trends caused by actual damage degradation and operation variety in the tracking matrix are separated by smooth orthogonal decomposition. According to smooth orthogonal values, dominant smooth orthogonal coordinates which reflect actual fault degradation trends are extracted. Finally, fault degradation process of bearing out-race is simulated. Rotating speed is varied during the degradation process. Applying the presented method to the degradation process tracking, the tracking matrix is built and decomposed by SOD, and the results show that the proposed method can track the evolution trend of the rotating machinery fault without the influence of operation condition variety.