A wavelet packet and residual analysis based method for hydraulic pump health diagnosis

This paper presents wavelet packet decomposition (WPD) and wavelet coefficient residual analysis based methods for hydraulic pump health diagnosis. A real-time pump health diagnosis system has been created on the basis of this method. This pump diagnosis system would analyse a short sequence of pump discharge pressure signals to detect if the pump was operating under a healthy condition or not. If the pump were operating with defective conditions, a further diagnosis would be implemented to identify the possible cause(s) of the defect(s). Based on the results obtained from a series of random laboratory tests by randomly selecting one of the four testing pumps 8 times, the developed WPD-residual analysis based pump diagnosis system was missing only one out of a total 32 diagnoses, which represented a 96.9 per cent accuracy rate in health diagnosis. Out of 23 fault diagnosing tests, 21 returned a correct diagnosis, resulting in a 91.3 per cent accuracy rate. The study also found that the accuracy rate could be further improved by taking available information from more packets to support fault diagnosis. It is worth pointing out that, while this method was tested against a hydraulic pump, it can also be applied to other equipment.