Sensitivity of Wavelet-Based Internal Leakage Detection to Fluid Bulk Modulus in Hydraulic Actuators

Fault detection and isolation (FDI) is a useful tool to investigate proper performance of dynamic systems. With respect to hydraulic actuators, as they are extensively used in industry, and are responsible for producing accurate displacements and high forces, FDI role is crucial. One of the phenomena that can affect the internal leakage detection is the variation in the value of fluid effective bulk modulus (EBM) originating mainly from the penetration of particles, water or air in the fluid. Hydraulic actuator internal leakage detection using wavelet transform technique is the focus of this paper. This study shows how the increase in the value of EBM affects the detection of the internal leakage using wavelet transform. Simulation results indicate that the increase in EBM value could change the sensitivity of the wavelet detailed coefficients to the internal leakage. Based on results, the level three detailed coefficient calculated from chamber one pressure signal could be an appropriate indicator to detect the internal leakage in a hydraulic actuator whose EBM is larger than normal value.