Annual Conference of the Prognostics and Health Management Society, 2009


A Prognostic Model for Electrohydraulic Servovalves

Lorenzo Borello1, Matteo Dalla Vedova2, Giovanni Jacazio3, Massimo Sorli4

1,2Politecnico of Turin - Department of Aerospace Engineering, Torino, Italy

3,4 Politecnico of Turin - Department of Mechanics, Torino, Italy

 

Abstract:

Servovalves are critical components of the hydraulic servos and their correct operation is mandatory to ensure the proper functioning of the controlled servosystem. A continuous monitor is typically performed that can detect a servovalve loss of operation, but falls short of recognizing other malfunctionings. A research was performed aimed at developing a prognostic algorithm able to identity the precursors of a servovalve failure and its degradation pattern. A model based technique was used that fuses several information obtained by comparing actual with expected response of the servovalve to recognize a degradation. The research was focused to flight control systems, but it can be used in other application areas. To assess the robustness of the algorithm a simulation test environment was developed. Simulations were run in which a servovalve controlled actuator was subjected to sequences of commands and loads representative of those encountered during actual operation, and variations of the servovalve characteristics within their normal range were applied. At the same time, degradations of the servovalve were superimposed and the merit of the prognostics algorithm was verified. The results showed an adequate robustness and confidence was gained in the ability to detect servovalve degradations with low risk of false alarms or missed failures.*

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