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.*