The Improvement of Instantaneous Angular Speed Estimation using Signals from a Dual Read Head for Monitoring Planetary Gearboxes

摘要

The Instantaneous Angular Speed (IAS) signals obtained from the shaft encoders are influenced by inevitable manufacture and installation errors of encoder wheels. These errors can lead to low accuracy or unsatisfied estimation of IAS and fault diagnostics. To improve the accuracy of IAS estimation, this paper presents a novel IAS extraction method based on a dual read head sensing system. The analysis of common encoder errors shows that the amplitude of error changes with angular positions on the encoder whereas the IAS to be monitored is independent of the angular position. Therefore, a dual read head IAS estimation method is proposed to estimate the erroneous IAS online, and subsequently is taken from overall IAS measurement. In this way, the estimate of rotor IAS is significantly improved for more accurate monitoring and diagnostics. Experimental evaluation shows that the new method allows the small planet fault in a planetary gearbox to be detected over a wide range of operating conditions.