Abstract:
Reliable condition indicators are necessary to perform effective diagnosis and prognosis.
However, the vibration signals are often corrupted with non-Gaussian noise and rotating machines
may operate under time-varying operating conditions. This impedes the application of conventional
condition indicators. The synchronous average of the squared envelope is a relatively simple yet
effective method to perform fault detection, fault identification and fault trending under constant
and time-varying operating conditions. However, its performance is impeded by the presence of
impulsive signal components attributed to impulsive noise or the presence of other damage modes in
the machine. In this work, it is proposed that the synchronous median of the squared envelope should
be used instead of the synchronous average of the squared envelope for gearbox fault diagnosis. It is
shown on numerical and experimental datasets that the synchronous median is more robust to the
presence of impulsive signal components and is therefore more reliable for estimating the condition
of specific machine components.
