Condition Monitoring of Rope-less Elevator Braking System Based on Wavelet Denoising

The rope-less elevator driven by Permanent Magnet Linear Synchronous Motor (PMLSM) is a new technology for high-rise buildings. In the practical operation, PMLSM inevitably encounters various kinds of turbulences which directly affect the rope-less elevator’s operation. The braking system is important for rope-less elevator safe and steady operation. Usually, the ordinary inspections are not able to detect some early stage faults in the elevator braking system. Based on the analyzing of braking system common faults, the article proposes a rope-less elevator braking system monitoring scheme and presents a method that uses air gap sensor, hydraulic pressure transducer and disc spring pressure sensor in order to detect running condition of braking system. The sampling signals are inevitably influenced by noise, which degrades the accuracy and precision of an analysis. De-noising by soft-thresholding is a new signal inspection method in wavelet analysis. On the base of briefly introducing wavelet de-noising theory, a wavelet de-noising analysis method is presented. The study shows that the useful information reflecting the condition of braking system can be effectively extracted from highly noised signals by soft-thresholding de-noising method.