Multistage Prognosis for Nonlinear Electromechanical System With Degradation Coupling and Maintenance

In this article, a multistage prognosis method is developed for the nonlinear electromechanical system in the presence of imperfect preventive maintenance (IPM) and degradation coupling effect (DCE). In this method, a composite degradation model incorporating IPM and DCE is proposed, by which the resultant remaining useful life (RUL) can be dynamically updated. First, the effects related to internal degradation, external degradation, and cumulative IPM are defined to facilitate the establishment of degradation model. Then, after the fault diagnosis with enhanced isolability using bond graph and improved temporal causal graph, degradation data obtained by cubature Kalman filter are used to estimate degradation model coefficients. Due to the RUL variation with occurrences of the first IPM and new fault, the multistage prognosis method is developed to update RULs at different stages that are distinguished by the first IPM of faulty component or the DCE caused by newly occurring fault. Finally, the proposed methods are validated by experimental results.