Inner Leakage Fault Diagnosis of Hydraulic Cylinder using Wavelet Energy

Inner leakage of hydraulic cylinder is a very serious failure in the hydraulic system and it can lead to many problems. A important fault diagnosis way is to detect the pressure signal. But the pressure signal is seriously influenced by pressure fluctuation and other noises. It is difficult to extract features from pressure singal. Aiming at the difficulty in extracting feature from pressure singal in fault diagnosis for leakage of hydraulic cylinder,a fault diagnosis approch based on monitoring preesure singal and wavelet energy is proposed in this article. According to the method, the enegry of different frequency bands after wavelet decomposition costitutes the eigenvectors at first, then these eigenvectors are input into BP network to identify faults. The experimental results show that three modes of no leakage, slighter leakage and severe leakage were correctly identified. This approach can be used in the leakage fault diagnosis of hydraulic cylinder.