This letter presents the diagnostic of electrohydraulic actuators. Different types of faults common in practice are considered such as a pump fault, abnormal viscous friction, oil contamination, and internal or external oil leakage. The entire diagnostic consists of two components: 1) reference tracking control; 2) recursive harmonic analysis. Firstly, the robust repetitive control is used such that the actuator position follows the harmonic reference signal. Secondly, the Fourier transforms of the control input at multiple harmonics are calculated recursively from sliding discrete Fourier transform. Instead of the raw control input, the modulated input signal is employed for better efficiency and robustness. The diagnostic decision is made based on distribution of the Fourier transforms. The effectiveness of the proposed method is demonstrated with numerical simulations. Diagnostic performance with different sizes of the sliding window is analyzed in terms of separation metrics, as a critical design parameter.
Bibliographical noteFunding Information:
Manuscript received September 14, 2020; revised November 28, 2020; accepted December 21, 2020. Date of publication January 5, 2021; date of current version June 23, 2021. Zongxuan Sun’s work is supported in part by the Center for Compact and Efficient Fluid Power (CCEFP). Recommended by Senior Editor F. Dabbene. (Corresponding author: Yongsoon Yoon.) Yongsoon Yoon is with the Department of Mechanical Engineering, Oakland University, Rochester, MI 48309 USA (e-mail: yongsoonyoon@ oakland.edu).
© 2017 IEEE.
- Fault detection
- fault diagnosis
- robust control