Field simultaneous estimation of residual unbalance and bearing dynamic coefficients for double-disk rotor-bearing system using dual augmented Kalman filter.

• Residual unbalance and bearing dynamic coefficients are estimated simultaneously. • Dual augmented Kalman filter is applied successfully in the estimation method. • The method performs a strong robustness in different measurement noise levels. • The reliability of the method is verified in different measurement configurations. Simultaneous estimation of the residual unbalance and bearing dynamic coefficients is of great significance to the dynamic analysis and rotor design of rotating machinery. However, traditional estimation methods are susceptible to routine scattering caused by the ill-posed problem and require external excitation forces, making them inconvenient and costly for engineering applications. Therefore, a novel simultaneous estimation method based on the augmented state-space model of the system combined with the dual augmented Kalman filter (DAKF) method is proposed for the double-disc rotor-bearing system without the external excitation force. The principle of this method is designed through an iterative strategy in the time domain, which only requires the steady-state unbalance responses of the two selected locations. To prevent the coupling relationship between the unbalance and the bearing dynamic coefficients from affecting the results, the estimation of the bearing dynamic coefficients is indirectly converted to the determination of the equivalent oil-film force according to the dynamic theory. Besides, features of the coupling relationship are investigated by the sensitivity analyses, proving that the coupling relationship has a significant influence on the estimation performance, especially for the bearing dynamic coefficients. Furthermore, simulations and experimental studies show that the proposed method can effectively estimate the bearing dynamic coefficients and unbalance parameters under different measurement noise levels, rotation speeds and measurement configurations. This study provides a comprehensive investigation into the estimation of dynamic characteristics and thereby establishes a reliable foundation for further assessment of the rotor-bearing system's overall performance. [ABSTRACT FROM AUTHOR]