Force balanced vibratory rate sensor
First Claim
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1. A force feed back inertial rate sensor comprising:
- a first support member,a second support member,an elongate beam cantilevered from said second support member, extending along a sensing axis about which rate of turn is to be measured, and having a free end,first signal generating means coupled with and responsive to vibration of said free end in a first plane including said sensing axis,first elongate drive means cantilevered from said first support member and coupled with said second support member and responsive to said first signal generating means for vibrating said elongated beam in said first plane at a frequency dependent upon the natural vibration of said elongate beam,second signal generating means coupled with and responsive to vibration components of said free end in a second plane including said sensing axis and normal to said first plane due to rate of turn of said support member about said sensing axis, andsecond elongate drive means cantilevered from said first and coupled with said second support member and responsive to said second signal generating means for vibrating said elongated beam in said second plane in a phase and amplitude such as to reduce the signal from said second signal generating means to zero whereby the signal supplied to said second driver means is proportional to said rate of turn about said sensing axis.
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Abstract
A vibratory inertial rate of turn sensor employs force feed back for maintaining the free end of a vibrating cantilever in a nulled lineal path when subjected to a turn about the beam axis, the electrical signal required for nulling being a measure of rate of turn of the craft. The output signal demodulation self-tracks the beam resonance frequency and the beam drive and null terms balance one another, tending to maintain the sensor scale factor constant over time and temperature. A unique pick-off and beam primary drive and restoring force drive configuration is provided.
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Citations
15 Claims
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1. A force feed back inertial rate sensor comprising:
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a first support member, a second support member, an elongate beam cantilevered from said second support member, extending along a sensing axis about which rate of turn is to be measured, and having a free end, first signal generating means coupled with and responsive to vibration of said free end in a first plane including said sensing axis, first elongate drive means cantilevered from said first support member and coupled with said second support member and responsive to said first signal generating means for vibrating said elongated beam in said first plane at a frequency dependent upon the natural vibration of said elongate beam, second signal generating means coupled with and responsive to vibration components of said free end in a second plane including said sensing axis and normal to said first plane due to rate of turn of said support member about said sensing axis, and second elongate drive means cantilevered from said first and coupled with said second support member and responsive to said second signal generating means for vibrating said elongated beam in said second plane in a phase and amplitude such as to reduce the signal from said second signal generating means to zero whereby the signal supplied to said second driver means is proportional to said rate of turn about said sensing axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A force feed back inertial rate sensor for providing a measure of the rate of turn thereof about a sensing axis comprising:
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a substantially rigid sensor support ring generally defining the sensing axis of said sensor and adapted to secure said sensor to a craft the turn rate of which about said axis is to be measured, an elongate cylindrical driver means of piezoelectric material having one end thereof secured to said support ring and having its axis coincident with and extending along said sensing axis, the other end of said driver means being formed in quadrants providing two pairs of diametrically opposed, orthogonal actuator elements, each pair of elements including electrodes adapted to be energized to produce opposed elongation and contraction thereto in the direction of said axis, an elongate beam having a flanged base portion secured to the ends of said actuator elements with said beam extending interiorly along said axis and its free end terminating closely adjacent said sensor support ring, first and second pairs of diametrically opposed pick-off means secured to said sensor ring adjacent said beam free end and axially aligned with corresponding pairs of said actuator elements for detecting motion of the beam free end in first and second orthogonal planes defined by said corresponding pick-off means and actuator elements, first electronic means coupled between said first pair of pick-off means and corresponding actuator elements for energizing said first pair of actuator elements so as to vibrate said beam through said beam base portion in said first plane at the natural resonant frequency of said beam, second electronic means coupled between said second pair of pick-off means and corresponding actuator elements and responsive to any components of said beam vibration in said second plane produced by a turn rate of said sensor about said sensing axis for energizing said second pair of actuator elements and vibrating said beam through said beam base portion in said second plane at said resonant frequency, the sense of said energization-producing vibration of said beam being such as to oppose said vibration component in said second plane whereby to reduce the same toward zero and thereby maintain vibration of said beam in said first plane, and means responsive to said second electronic means for providing said rate of turn measure.
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Specification