结合 LSTM 和 Self‑Attention 的滚动轴承 剩余使用寿命预测方法
Combination of LSTM and Self‑Attention for remaining life prediction of rolling bearings
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摘要: 为了构建准确表征滚动轴承退化过程的趋势性健康度指标,提高滚动轴承剩余使用寿命(Remaining Useful Life,RUL)的 预 测 精 度 ,提 出 了 一 种 结 合 长 短 期 记 忆(Long?Short Term Memory,LSTM)和 自 注 意 力 (Self?Attention)机制的神经网络模型(LSTM?SA)用于滚动轴承 RUL 预测。利用包络解调获得原始信号的包络 谱,再将包络谱分段并计算对应频段的皮尔逊相关系数,得到具有单调性和趋势性的退化特征;将退化特征归一化 处理后作为 LSTM?SA 模型的输入,并利用 LSTM 自适应提取退化特征时间上的内部相关性以及 Self?Attention 对 关键信息的筛选,消除无用信息的干扰,挖掘深层次特征,构建健康度指标并得到退化曲线;确定失效阈值,利用最 小二乘法拟合退化曲线,预测寿命失效点,实现滚动轴承的 RUL 预测。在 PHM2012 数据集上的实验结果表明,所 提出的方法相比于其他文献,平均绝对误差分别降低了 43.18%,62.57% 和 59.44%,平均得分分别提高了 10.87%, 45.71% 和 34.21%;在工程实际数据中的实验结果表明,所提出方法的平均预测误差分别比 Standard?RNN 和 CNN 方法降低了 39.58% 和 74.86%。Abstract: In order to construct a trend health index that accurately characterizes the degradation process of rolling bearings and im ? prove the prediction accuracy of remaining useful life (RUL) of rolling bearings, a neural network model (LSTM-SA) combining long-short term memory (LSTM) and self-attention mechanism (Self-Attention) is proposed for RUL prediction of rolling bear? ings. The envelope spectrum of the original signal is obtained by using envelope demodulation, and then the envelope spectrum is segmented and the Pearson correlation coefficients of the corresponding frequency bands are calculated to extract the degradation features with monotonicity and trend. The degradation features are normalized and processed as the input of the LSTM-SA model, and the LSTM is used to adaptively extract the temporal internal correlation of the degradation features and the Self-Attention is used to screen key information. By eliminating the interference of useless information and mining deep-level features, healthiness in? dexes are constructed and degradation curves can be obtained. By determining the failure threshold, the degradation curves are fit? ted by the least squares method, and the life failure point is predicted, which realize the RUL prediction of rolling bearings. The ex? perimental results on the PHM2012 dataset show that the proposed method reduces the average absolute error by 43.99%, 63.11% and 60.00%, respectively, and improves the average score by 10.87%,45.71% and 34.21%, respectively, compared with other literature. The experimental results on the actual engineering data show that the average prediction error of the proposed method is higher than that of standard-RNN and CNN by 39.58% and 74.86%, respectively.