Instantaneous Angular Speed: Encoder-Counter Estimation Compared with Vibration Data

Conference paper
Part of the Lecture Notes in Mechanical Engineering book series (LNME)


In rotating machinery, actions of the moving parts take place at specific angular positions rather than at specific times. For this reason, having a geometrical reference, such as the one provided by an encoder, and studying the Instantaneous Angular Speed (IAS) variations can provide a large amount of information about the health status of the machine. In fact, from the variation of the IAS during the machine loads’ cycle it is possible to identify defects and faults. The current work focuses on the estimation of the IAS through the Elapsed Time (ET) method, using a counter in order to measure the time elapsed between the pulses of an encoder. Both IAS and vibration measurement are conducted on an asynchronous four poles electrical motor driven by 50 Hz line current, without load. The study compares the order analysis of both signals. The bearing’s Fundamental Train Frequency is detected using IAS estimation.


Instantaneous angular speed Encoder Elapsed time method AC DC electrical machine Slip effect 



This research is supported by Università degli Studi di Trieste, Nidec ASI S.p.A. and "Programma Operativo del Fondo Sociale Europeo 2007/2013 della Regione Autonoma Friuli Venezia Giulia".


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Università degli Studi di TriesteTriesteItaly

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