An adaptive approach for recovering overlapping echoes in oil film thickness measurement by ultrasound

Obtaining the isolated reflfection from the oil flm layer is significant for oil film thickness measurement using ultrasonic spring model. The reflection from the substrate-Babbitt interface will overlap with the reflection from the oil film layer, and will render the iltrasonic model invalid, for oil film thickness measurement in thrust bearings with thin liner. An adaptive method was developed to recover overalpping echoes and to obtain isolated reflected signal from the oil film layer accurately. A genertic-algorithm-based support matching pursuit was developed to supply the optimal echo number and initial parameters guesses automatically and efficiently. THe traditional expectation maximization model was used to fine tune the accurate results. Results showed that the developed method performed well on recovering overlapping echoes adaptively.