Two-axis angular rate gyroscope

• US 4,811,613 A
• Filed: 09/04/1987
• Issued: 03/14/1989
• Est. Priority Date: 09/04/1987
• Status: Expired due to Term

• Current Assignee: Tele Atlas North America (TomTom NV)
• Original Assignee: Etak, Inc. (TomTom NV)
• Inventors: Taylor, Charles S., O'Brien, Terence J., Phillips, Alan C.
• Primary Examiner(s): Bonck, Rodney H.
• Application Number:
  US07/093,007
• Time in Patent Office: 557 Days
• Field of Search: 74/5.6 D, 74/5 F, 73/504, 73/505, 324/60 C
• US Class Current: 74/5.60D
• CPC Class Codes: G01C 19/08 electrically driven G01C19/14 takes precedence
• 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 74/1275 Electrical
• CPC Class Codes: Y10T 74/1293 Flexure hinges for gyros

Abstract

A two-axis angular rate gyroscopic apparatus is provided having a rotatable dish. The dish has a central hub portion and a plurality of flexible members, each of which extends from the hub portion. The entire disk is electrically conductive and connected to a reference potential. A plurality of electrically conductive members which are mounted end-to-end are located on an insulated plate mounted adjacent to the disk. A motor is provided for rotating the disk at approximately 2000 rpm. In addition, each of the flexible members in the disk has a pie-shaped section removed therefrom in order to increase its flexibility. By increasing the flexibility of the movable members, performance at low motor speeds is facilitated. An electronic circuit provides an output corresponding to the differential capacitance between the rotating disk and the members on the plate mounted adjacent thereto.

Claims

1. A two-axis angular rate gyroscopic apparatus comprising:

an electrically conductive rotatable disk, said disk having a central hub portion and a plurality of flexible members, each of which extends from said hub portion and comprises an annular outer portion and a pair of radially extending leg members, said leg members extending from said hub portion;

means for connecting said disk to a source of reference potential;

a plurality of electrically conductive plate members which are mounted on an insulating plate adjacent to said disk;

means for rotating said electrically conductive disk adjacent to said plate members about an axis of rotation; and

electrical circuit means coupled between said plate members and said electrically conductive flexible members of said disk for measuring a change in the capacitance between each of said plate members and said electrically conductive flexible members of said disk when said electrically conductive flexible members of said rotatable disk undergo precession as said rotatable disk is rotated about an axis perpendicular to said axis of rotation, said change in capacitance being a function of said rate of rotation of said axis of rotation about said axis perpendicular to said axis of rotation.

2. A two-axis angular rate gyroscopic apparatus comprising:

an electrically conductive rotatable disk, said disk having a central hub portion and a plurality of flexible members, each of which extends from said hub portion and comprises an annular outer portion and a pair of radially extending leg members, said leg members extending from said hub portion;

means for connecting said disk to a source of reference potential;

a plurality of pairs of electrically conductive spaced plate members which are mounted end-to-end in a circle on an insulating plate adjacent to said disk such that one of said plate members in a pair of said plate members is mounted opposite to the other of said plate members in said pair;

means for rotating said electrically conductive disk adjacent to said plate members about an axis of rotation; and

electrical circuit means coupled between said plate members and said electrically conductive flexible members of said disk for measuring a change in the capacitance between each of said plate members and said electrically conductive flexible members of said disk when said electrically conductive flexible members of said rotatable disk undergo precession as said rotatable disk is rotated about an axis perpendicular to said axis of rotation, said change in capacitance being a function of said rate of rotation of said axis of rotation about said axis perpendicular to said axis of rotation, said electrical circuit means including a pair of current sources for charging opposite ones of said plate members relative to said disk, means for periodically switching said current sources between each of said opposite plate members to compensate for variations in said current sources, means for periodically discharging said opposite plate members relative to said disk, said charging and said discharging producing a pair of sawtooth voltages, and means for filtering and differentially amplifying said sawtooth voltages for providing an output signal which is proportional to the inverse of the differential capacitance between said opposite plates and said disk.

3. A two-axis angular rate gyroscopic apparatus comprising:

an electrically conductive rotatable disk, said disk having a central hub portion and a plurality of flexible members, each of which extends from said hub portion and comprises an annular outer portion and a pair of radially extending leg members, said leg members extending from said hub portion;

means for connecting said disk to a source of reference potential;

a plurality of electrically conductive plate members which are mounted on an insulating plate adjacent to said disk;

means for rotating said electrically conductive disk adjacent to said plate members about an axis of rotation; and

electrical circuit means coupled between said plate members and said electrically conductive flexible members of said disk for measuring a change in the capacitance between each of said plate members and said electrically conductive flexible members of said disk when said electrically conductive flexible members of said rotatable disk undergo precession as said rotatable disk is rotated about an axis perpendicular to said axis of rotation, said change in capacitance being a function of said rate of rotation of said axis of rotation about said axis perpendicular to said axis of rotation, said electrical circuit means including a voltage-to-pulse rate converter having a sawtooth voltage generator and a comparator, capacitor means for coupling said sawtooth voltage generator to a first input of said comparator, a source of reference potential, means for coupling said source of reference potential to said first input, and means for coupling said change of capacitance as an input signal to a second input of said comparator.