Flexible disc rotor rate gyro

• US 4,916,957 A
• Filed: 05/09/1988
• Issued: 04/17/1990
• Est. Priority Date: 05/09/1988
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Unisys Corporation
• Inventors: Quermann, Thomas R.
• Primary Examiner(s): Bonck, Rodney H.
• Application Number:
  US07/191,504
• Time in Patent Office: 708 Days
• Field of Search: 74/5 F, 74/5.5, 74/5.6 D, 73/504
• US Class Current: 74/5.5
• CPC Class Codes: G01C 19/06 Rotors
• CPC Class Codes: G01C 19/28 Pick-offs, i.e. devices for taking-off an indication of the displacement of the rotor axis
• CPC Class Codes: Y10T 74/1257 Damping
• CPC Class Codes: Y10T 74/1275 Electrical

Abstract

A gyroscopic rate sensor has a motor driven shaft on which is mounted a flexible disc rotor enclosed in a gas-filled housing with a rotating rigid plate, also mounted on the shaft, to provide viscous gaseous restraint. A rotating capacitive plate assembly referenced to the drive motor spin axis provides a stable electrical output signal proportional to periodic deflections of the disc rotor. By perforating the disc rotor near the spin axis, spring restraint is minimized while the squeeze film damping provides improved dynamic response.

Claims

1. A gyroscopic rate sensor comprising:

housing means,

drive shaft means supported for rotary motion within said housing means,

motor rotor means adapted for spinning about a spin axis of said drive shaft means,

flexible disc rotor means coupled to said motor rotor means and including a rotor body and integrally formed articulating support means for providing a predetermined spring restrain coefficient and a rotor spin axis substantially independent of said spin axis of said drive means, so that said disc rotor means responds to precessional forces as a rigid rotor articulated at said drive shaft means,

squeeze film damping means for damping said flexible disc rotor means, comprising a substantially rigid disc coupled for rotation with said motor rotor means in spaced relationship therewith and in spaced relationship with said flexible disc rotor means and having a diameter greater than said flexible disc rotor and a thickness substantially greater than said flexible disc rotor, fluid means surrounding said flexible disc rotor means and confined within said housing means, so that undesired oscillations of said rotor means are effectively damped while allowing substantially free deflection of said spin axis of said flexible disc rotor means, and

detection means fixed in relation to said drive shaft means and substantially mechanically independent of said housing means for sensing the angular deflection of said rotor spin axis with respect to said spin axis of said drive shaft means in response to gyrodynamic reaction when said flexible disc rotor means is precessed about an axis perpendicular to said spin axis of said drive shaft means.

2. A gyroscopic rate sensor as set forth in claim 1, said means for sensing deflection comprising rotary capacitance means responsive to oscillations of said disc rotor means with respect to a plane perpendicular to said spin axis.

3. A gyroscopic rate sensor as set forth in claim 2, said rotary capacitance means further comprising:

rotary dielectric support means having first and second planar opposing surfaces and coupled to said motor rotor means for rotary motion about said spin axis of said drive shaft means, said first surface disposed in spaced relationship proximate to said flexible disc rotor means,

first diskoidal capacitive element means disposed on said second planar surface of said rotary dielectric support means,

first segmented capacitive element means comprised of a plurality of arcuate elements circumferentially disposed about said first diskoidal capacitive element means, and

second segmented capacitive element means comprised of a plurality of arcuate elements circumferentially disposed on said first planar surface of said rotary dielectric support means, ones of said elements thereof corresponding to ones of said first segmented capacitor element means and conductively coupled thereto, said second segmented element means further capacitively coupled to said flexible disc rotor means for sensing deflections thereof, said deflections causing a variation in effective capacitance in proportion thereto.

4. A gyroscopic rate sensor, as set forth in claim 3, further comprising motor means for applying said rotary motion to said drive shaft means, said motor means including stator means defining a capacitive element coupled to said housing and rotor means defining a further capacitive element coupled to said stator means, said coupled capacitive elements forming a motor means capacitance of substantially constant capacitance with respect to rotation of said rotor means.

5. A gyroscopic rate sensor as set forth in claim 4, further comprising:

stationary dielectric support means coupled to said housing for supporting second diskoidal capacitive element means distal to said rotary dielectric support means, said stationary dielectric support means in spaced relationship to said rotary dielectric support means,

third segmented capacitive element means comprised of a plurality of arcuate elements circumferentially disposed about said second diskoidal capacitive element means, ones of said third segmented capacitive element means capacitively coupled to a plurality of elements of said first segmented capacitive element means, and

means for coupling said first and second diskoidal capacitive element means, said first and third segmented capacitive element means, and said motor means capacitance to form an electrical bridge circuit responsive to a source of regular excitation and providing outputs for measuring the deflections of the spin axis of said disc rotor means along radial axes in quadrature and perpendicular to said spin axis of said drive shaft means, said outputs reference along predetermined coordinates with respect to said housing means.

6. A gyroscopic rate sensor as set forth in claim 5, wherein said motor means comprises an induction motor.

7. A gyroscopic rate sensor as set forth in claim 6, wherein said motor means comprises a synchronous motor.

8. A gyroscopic rate sensor as set forth in claim 7, wherein said source of regular excitation comprises a sinusoidal oscillator.

9. A gyroscopic rate sensor as set forth in claim 5, further comprising:

pairs of diametrically disposed elements of said third segmented element means disposed in quadrature for sensing rotor deflections corresponding to a precession rate about two perpendicular axes, each said axis perpendicular to said spin axis of said housing means.

10. A gyroscopic rate sensor as set forth in claim 9, further comprising preamplifier means coupled to said diametrically opposing pairs of said first segmented capacitive element means for providing an output signal representative of periodic deflection of said flexible disc rotor means.

11. A gyroscopic rate sensor as set forth in claim 10, further comprising demodulator means coupled to receive said output signal in alternating current form and for deriving a direct current output signal corresponding thereto.

12. The gyroscopic rate sensor as set forth in claim 11, wherein said direct current output signal is representative of the direction and angular rate of motion of said gyroscopic rate sensor.

13. A gyroscopic rate sensor as set forth in claim 1, further comprising:

means perforating said flexible disc rotor means, diametrically opposed and extending from substantially said drive shaft means spin axis along a predetermined radial extent for providing a predetermined spring restraint coefficient of said disc rotor means, so that said disk rotor means responds to precessional forces as a rigid rotor articulated at said drive shaft means.

14. A gyroscopic rate sensor as set forth in claim 13, said flexible disc rotor means further comprising:

a perforated relief area defining first and second radial members forming said articulating support means for torsionally suspending said disc rotor means about said spin axis of said drive motor means,

said first and second members having a predetermined thickness selectively reduced with respect to a planar thickness of said rotor body so as to provide a predetermined spring restraint.

15. A method for sensing precession rate in a gyroscopic rate sensor having a housing enclosing flexible rotor disc of unitary construction, a drive motor for spinning the rotor disc along a shaft spin axis, and a detector for sensing deflections of the spin axis of the rotor disc in accordance with a precession rate of the sensor, wherein the improvement comprises:

capacitively detecting deflections of said rotor disc spin axis with respect to said shaft spin axis along predetermined coordinate axes with respect to said housing,

capacitively isolating said detector to provide mechanical independence from said housing,

providing an integrally formed strain relief axially disposed within said rotor disc to minimize the spring restraint coefficient, and

providing a rigid disc in spaced relationship with said rotor disc for damping said rotor disc when surrounded by a gaseous atmosphere, thereby to restrain angular and axial motion of said rotor disc.