A signal processing approach to bearing fault detection with the use of a mobile phone

According to statistics, bearings are the most often failing elements of low voltage motors. At the same time diagnostics of rolling element bearings constitutes a well-established part of the rotating machinery condition monitoring domain. In many cases however the cost of installing a high-end accelerometer based bearing condition monitoring system, which is currently the most common approach in the industry, might be difficult to justify on non-critical machinery due to potentially long payback period on the investment. This text investigates the possibility of performing condition monitoring of rolling element bearings based on acoustic signals recorded by a standard, easily accessible mobile phone. The main difficulty in using mobile phone-embedded microphone for rotating machinery diagnostic purposes is the fact that the frequency response of the mobile phone microphone is very poor below 200Hz. The results presented in this text seem to indicate that with an appropriate signal processing approach, it is possible to indicate the presence of faults in the bearings.