Method of minimizing bias and achieving mode alignment by trimming a vibrating rate sensor
AssigneeBritish Aerospace Public Limited Company
InventorsMalcolm P. Varnham, James McInnes
Life of this patent
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Abstract
A vibrating cylindrical rate sensor (10) is mechanically balanced and mode aligned with respect to the vibrating portion of the sensor (10) by removing material from a vibrating portion of the vibrating cylinder (34) after the drive and pick-off transducers (30, 32, 30a, 18, 20) are fixed to the vibrating portion of the vibrating cylinder (34) of the cylindrical rate sensor (10).
Claims4
A method of minimizing bias and achieving mode alignment by trimming an effective transducer position of a vibrating rate sensor made of piezoelectric material of a type having a vibrating portion, a primary drive transducer, a secondary drive transducer, a primary pick-off transducer, and a secondary pick-off transducer, said method including steps of:
- (a) applying a sinusoidal signal to said primary drive transducer;
- (b) adjusting a frequency of said sinusoidal signal applied to said primary drive transducer until a desired first vibration mode is excited in said vibrating portion and a phase of a signal from said primary pick-off transducer is at 90 degrees with respect to a phase of said sinusoidal signal applied to said primary drive transducer;
- (c) measuring said signal from said primary pick-off transducer as a primary vibratory mode frequency (f.sub.np);
- (d) applying a sinusoidal signal to said secondary drive transducer;
- (e) adjusting a frequency of said sinusoidal signal applied to said secondary drive transducer until a desired second vibration mode is excited in said vibrating portion and a phase of a signal from said secondary pick-off transducer is at 90 degrees with respect to a phase of said sinusoidal signal applied to said secondary drive transducer;
- (f) measuring said signal from said secondary pick-off transducer as a secondary vibratory mode frequency (f.sub.ns);
- (g) ensuring that a modal frequency split between said primary vibratory mode frequency and said secondary vibratory mode frequency is less than a given value which is less than said primary vibratory mode divided by 2Q;
- (i) removing material from said vibrating portion at a position between said primary drive transducer and said secondary drive transducer until a component of said signal from said secondary pick-off transducer is in quadrature with respect to said signal from said primary pick-off transducer is zero.
A mode aligned vibrating cylindrical rate sensor comprising:
- a vibrating cylinder comprised of piezoelectric material;
- a plurality of separate electrodes formed on an outer surface of said vibrating cylinder at spaced intervals, said separate electrodes and said piezoelectric material of said vibrating cylinder forming a respective plurality of separate transducers;
- and
- an amount of said piezoelectric material being removed from a rim of said vibrating cylinder at a position between two adjacent ones of said plurality of separate transducers so as to minimize bias and achieve mode alignment of said vibrating cylinder.
Dependencies are inferred from the claim text.