Patent ID: 6697759
Filing Date: 2004-02-24
Classification: G01M,G01P

Abstract:
A method of determining speed of rotation of a motor (1), the method comprisingconnecting a measuring sensor (2) to the motor (1); determining the synchronous speed of the motor (1); setting the length of a measurement period (T); setting a sampling frequency (fs); collecting samples (x[n]) with a measuring sensor (3) at the sampling frequency (fs), set on the basis of mechanical vibration of the motor (1), for the duration of the measurement period (T); storing the samples (x[n]) in the memory of a data carrier (4) as measurement data of a fixed format, determining the speed of rotation of the motor (1) from the measurement data by determining the cycle length of a periodic vibration signal in the time domain by applying a maximum likelihood estimate calculated by maximizing a maximum likelihood function (J) adjusted to the measurement data, the speed of rotation being obtained from a frequency point (13f) where the maximum likelihood function (J) obtains its maximum value (13max).