Patent ID: 8806951

Claim:
Instrument for determining a quantity associated with a force exerted on a rotor, which instrument includes: a rotor; a stator; at least one bearing for mounting the rotor to allow at least limited displacement relative to the stator, the bearing including opposing bearing surfaces, arranged to be kept generally fixed in position, in use, relative to the rotor and stator, respectively, at least one bearing having an adjustable stiffness in a direction normal to the bearing surfaces; a system for controlling a parameter for adjusting the stiffness of the at least one bearing; and a system for determining a value of a quantity associated with a second force exerted between the rotor and the stator and opposing the force associated with the quantity to be determined, wherein the instrument further includes a data processing system for correcting the determined value of the quantity associated with the second force by a bias value, obtained using a mapping having as a parameter a variable representative of the parameter for adjusting the stiffness.