Comparison of Change Detection Methods for a Residual of a Hydraulic Servo-Axis

Authors:	Muenchhof Marco, University of Technology at Darmstadt, Germany Isermann Rolf, University of Technology at Darmstadt, Germany
Topic:	6.4 Safeprocess
Session:	Electromechanical Applications of Fault Diagnosis and Fault Tolerant Control
Keywords:	hydraulic actuators, detection algorithms, alarm systems, fault detection

Abstract

Different methods for change detection of signal features are compared for a residual generated at a hydraulic servo axis. The residual is based on a physical model of the pressure buildup inside the hydraulic cylinder. Nevertheless, it is augmented with an observer to counteract slight model impurities even over prolonged periods of operation. Different sensor faults are introduced, which affect the mean and/or the variance of the residual. Methods have been implemented, which allow to detect changes in the mean and variance of a signal. These methods are compared in terms of the size of the smallest detectable fault, time-to-detection and computational expense. All results have been verified experimentally.