The concentration of wear debris in used lubricating oil is generally observed from spectral oil analysis. The element concentration data are one of the commonly used oil field data for degradation evaluation of power-shift steering transmission. However, in practical applications, the underlying degradation degree of the power-shift steering transmission is difficult to evaluate due to the complexity of element concentration data. To solve this problem, we propose a health index extraction methodology using a weighted average method to better characterize the underlying degradation, which leads to an accurate estimation of the residual life before the power-shift steering transmission needs to be maintained. The extracted health index not only maximizes the monotonic trend of underlying degradation but also minimizes the failure threshold variance between different power-shift steering transmissions. The method includes element concentration data modification, data selection, and data fusion steps that result in a reasonable power-shift steering transmission degradation model. Finally, a case study is provided to illustrate the proposed method. The results show that the extracted health index outperforms each selected element concentration data.

通常从光谱油分析中观察到用过的润滑油中的磨损碎片浓度。元素浓度数据是用于动力换挡转向变速器的退化评估的常用油田数据之一。然而，在实际应用中，由于元素浓度数据的复杂性，难以评估动力换挡转向变速器的潜在退化程度。为了解决这个问题，我们提出了一种使用加权平均法的健康指标提取方法，以更好地表征潜在的退化，从而可以在需要保持动力换挡转向变速器之前准确估算剩余寿命。所提取的健康指数不仅使潜在退化的单调趋势最大化，而且使不同动力换挡转向变速器之间的故障阈值差异最小。该方法包括元素浓度数据修改，数据选择和数据融合步骤，从而形成合理的动力换挡转向变速器降级模型。最后，提供了一个案例研究来说明所提出的方法。结果表明，提取的健康指数优于每个选定的元素浓度数据。