Atlantic Inertial Systems, Inc.

Bae Systems, Inc.

Andrew Kazer

Kevin Townsend

Christopher Paul Fell

Alan R Malvern

Alan Richard Malvern

A vibrating structure gyroscope includes an annular resonator arranged to vibrate in a plane in response to electrostatic driving forces and a set of capacitive drive electrodes arranged to apply a voltage creating an electrostatic driving force to excite a primary cos n&#x3b8; resonance along a primary axis at a primary frequency f, such that Coriolis forces, resulting from an angular rate applied about an out-of-plane axis, induce a secondary cos n&#x3b8; resonance along a secondary axis at a secondary frequency f. The gyroscope also includes digitally-controlled first and second sets to creating a static electrostatic balancing.

Vibrating structure gyroscopes

An angular velocity sensor or gyroscope has a ring and a primary drive transducer arranged to cause the ring to oscillate in a primary mode substantially at the resonant frequency of the primary mode of the ring. A primary control loop receives primary pick-off signals from the primary pick-off transducer and provides primary drive signals to the primary drive transducer so as to maintain resonant oscillation of the ring. The primary control loop includes a demodulator arranged to determine the amplitude of the fundamental frequency of the primary pick-off signals and a demodulator arranged to determine the amplitude of the second harmonic frequency of the primary pick-off signals and a drive signal generator arranged to produce the primary drive signals with an amplitude that is dependent on a ratio of the amplitude of the second harmonic frequency of the primary pick-off signal over the amplitude of the fundamental frequency of the primary pick-off signal as derived by a divider.

Angular velocity sensors

A method for reducing bias error in a Vibrating Structure Gyroscope having a vibrating structure, a primary drive for putting the vibrating structure into carrier mode resonance, a primary pick-off device for sensing carrier mode motion, a secondary pick-off for sensing response mode vibration of the vibrating structure in response to applied rotation rate, a secondary drive for applying a force to control the response mode motion, closed loop primary control loops for maintaining a fixed amplitude of motion at the primary pick-off device, for maintaining the drive frequency at the resonance maximum, and secondary control loops for maintaining a null at the secondary pick-off device. In the method the ratio SFover SFis measured from the secondary control loop to provide a direct measurement of Sin (&#x3c6;+&#x3c6;), according to the relationship SF=SF&#xd7;Sin (&#x3c6;+) where SFis the quadrature scalefactor SFis the in-phase scalefactor, &#x3c6;is the phase error in the secondary drive and &#x3c6;is the phase error in the primary pick-off device. The total phase error &#x3c6;is obtained directly from the measured Sin (&#x3c6;+&#x3c6;) according to the relationship; &#x3c6;=&#x3c6;+&#x3c6;and phase corrections applied to the secondary drive and/or primary pick-off device to reduce the phase error &#x3c6;, and hence the quadrature bias error, to enhance the performance of the gyroscope.

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Taunton, United Kingdom

Andrew Kazer