Patent ID: 7860665
Filing Date: 2010-12-28
Classification: G01L

Abstract:
1. A method of determining a torque induced in a rotating shaft, the shaft having a torsional oscillation frequency that is dependent on a stiffness of the shaft, wherein the torsional oscillation frequency and the stiffness are dependent upon operating conditions of the shaft, the method comprising: measuring the torsional oscillation frequency of the rotating shaft; measuring a twist induced in the rotating shaft by the torque; using the measured value of the torsional oscillation frequency and the measured value of the induced twist to determine the torque induced in the shaft, wherein the torsional oscillation frequency of the shaft and the induced twist are measured at a first set of operating conditions; and determining a torsional oscillation frequency of the shaft at a second set of operating conditions at which the stiffness of the shaft is determined to determine the torque induced in the shaft.