An Intelligent Combined Method Based on Power Spectral Density, Decision Trees and Fuzzy Logic for Hydraulic Pumps Fault Diagnosis

Recently, the issue of machine condition monitoring and fault diagnosis as a part of maintenance system became global due to the potential advantages to be gained from reduced maintenance costs, improved productivity and increased machine availability. The aim of this work is to investigate the effectiveness of a new fault diagnosis method based on power spectral density (PSD) of vibration signals in combination with decision trees and fuzzy inference system (FIS). To this end, a series of studies was conducted on an external gear hydraulic pump. After a test under normal condition, a number of different machine defect conditions were introduced for three working levels of pump speed (1000, 1500, and 2000 rpm), corresponding to (i) Journal-bearing with inner face wear (BIFW), (ii) Gear with tooth face wear (GTFW), and (iii) Journal-bearing with inner face wear plus Gear with tooth face wear (B&GW). The features of PSD values of vibration signal were extracted using descriptive statistical parameters. J48 algorithm is used as a feature selection procedure to select pertinent features from data set. The output of J48 algorithm was employed to produce the crisp if-then rule and membership function sets. The structure of FIS classifier was then defined based on the crisp sets. In order to evaluate the proposed PSD-J48-FIS model, the data sets obtained from vibration signals of the pump were used. Results showed that the total classification accuracy for 1000, 1500, and 2000 rpm conditions were 96.42%, 100%, and 96.42% respectively. The results indicate that the combined PSD-J48-FIS model has the potential for fault diagnosis of hydraulic pumps. Keywords—Power Spectral Density, Machine Condition Monitoring, Hydraulic Pump, Fuzzy Logic. Kaveh Mollazade is MSc student in Department of Mechanical Engineering of Agricultural Machinery, faculty of Biosystems Engineering, University of Tehran, Karaj, Iran. (Corresponding author, phone: +98-918972-0639; fax: +98-21-665-93099; e-mail: [email protected] , [email protected]). Hojat Ahmadi is assistant professor in Department of Agricultural Machinery Engineering, faculty of Biosystems Engineering, University of Tehran, Karaj, Iran (e-mail: [email protected]). Mahmoud Omid is associate professor in Department of Agricultural Machinery Engineering, faculty of Biosystems Engineering, University of Tehran, Karaj, Iran (e-mail: [email protected]). Reza Alimardani is professor in Department of Agricultural Machinery Engineering, faculty of Biosystems Engineering, University of Tehran, Karaj, Iran (e-mail: [email protected]).