# US 4,397,185 A · Inertial instrument with cup-shaped inertial mass

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- Number: US 4,397,185 A
- Document ID: US4397185A
- Status: Granted
- Kind: A
- Application number: 06/262,993
- Filed: 1981-05-12
- Granted: 1983-08-09
- Earliest claimed: 1981-05-12
- Assignees: Incosym, Inc.
- Inventors: Robert J. G. Craig; James J. Imbault; John E. Fitzgerald
- Web page: https://patentgrep.com/patent/US4397185A

## CPC

- G01P 15/14: by making use of gyroscopes (gyroscopes per se G01C19/00)
- G01C 19/22: torsional
- G01C 19/28: Pick-offs, i.e. devices for taking-off an indication of the displacement of the rotor axis
- Y10T 74/1293: Flexure hinges for gyros
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An inertial instruments uses a suspension structure that is exterior to and surrounds a cup shaped inertial mass which carries torquing magnets within the cup. Torquer coils are also located within the cup. In a preferred embodiment, axially magnetized disc magnets within the cup cooperate with toroidal torquer coils. In other embodiments segmented or bar magnets are used. The instrument can be used either as a gyroscope by coupling the suspension to a rotor, or as an accelerometer.

## Claims

### Claim 1

An inertial instrument having a central axis and including:
(1) an inertial mass element having a substantially cup shape, coaxial with the central axis;
(2) suspension means direct coupled to said mass element exterior to the outside of said cup shape;
(3) flexure means symmetrically coupling said suspension means to a support structure for permitting limited rotation of said inertial mass element about a first axis orthogonal to the central axis;
(4) pickoff means adjacent said inertial mass element for detecting and signalling rotational motion about said first axis; and
(5) torquer means for imparting to said inertial element a rotational motion about said first axis.

### Claim 2 (depends on 1)

The inertial instrument of claim 1 wherein said flexure means are located exterior to said cup shaped inertial mass element.

### Claim 3 (depends on 1)

The inertial instrument of claim 1 further including permanent magnet means carried within said inertial mass element cup shape for generating a magnetic flux path extending generally at right angles to the central axis, whereby said torquer means acts upon said permanent magnet means.

### Claim 4 (depends on 3)

The inertial instrument of claim 3 wherein said permanent magnet means include at least one disc magnet concentrically mounted within said cup shape.

### Claim 5 (depends on 4)

The inertial instrument of claim 4 wherein said disc magnet is polarized in the direction of the central axis.

### Claim 6 (depends on 3)

The inertial instrument of claim 3 wherein said permanent magnet means include a bar magnet mounted within said cup shape.

### Claim 7 (depends on 6)

The inertial instrument of claim 6 wherein said torquer means include a circular coil concentric with the central axis extending into said cup shape between said bar magnet and the cup wall.

### Claim 8

In an improved accelerator including a frame, and an insensitive axis, the combination comprising:
(a) a cup shaped inertial mass element coaxially aligned with the insensitive axis;
(b) flexural mounting means having a cylindrical opening adapted to receive said inertial mass element at the peripheral edge of said mass element and permitting said mass element limited rotational movement about at least a first axis orthogonal to the insensitive axis;
(c) magnetic means disposed in the interior of the cup of said cup shaped mass element; and
(d) torquer coil means fixed to a reference frame but extending into the cup interior adjacent to said magnetic means and co-operable therewith for maintaining said mass element in a plane orthogonal to the insensitive axis,
whereby said flexural mounting means is accessible for balancing and adjusting with the instrument otherwise assembled and operable.

### Claim 9 (depends on 8)

The accelerometer of claim 8 whereby the plane including the center of mass of said inertial mass element is non-coplanar with the plane of said first axis.

### Claim 10 (depends on 9)

The accelerometer of claim 9 wherein said flexural mounting means permits said mass element limited rotation motion about a second axis, orthogonal to and coplanar with said first axis.

### Claim 11 (depends on 8)

The accelerometer of claim 8 further including a pendulous mass element coupled to said inertial mass element.

### Claim 12 (depends on 8)

The accelerometer of claim 8 wherein said magnetic means include at least a first disc shaped permanent magnet polarized in a direction parallel to the insensitive axis.

### Claim 13 (depends on 12)

The accelerometer of claim 12 wherein said magnetic means further include second and third disc magnets, respectively, adjacent said first disc magnet, polarized in a direction parallel to the insensitive axis and having similar poles adjacent said first magnet for directing the flux in a direction substantially orthogonal to the insensitive axis, whereby the flux path is directed through said torquer coil means.

### Claim 14 (depends on 8)

The accelerometer of claim 8 wherein said magnetic means include a bar magnet having an axis orthogonal to the insensitive axis.

### Claim 15 (depends on 14)

The accelerometer of claim 14 wherein said torquer means include a concentric coil positioned in the interior of the cup between the cup wall and said magnetic means.

### Claim 16

An improved dynamically tuned gyroscope including a frame, motor means fixed to the frame and including a shaft, rotatable about a spin axis, the combination comprising:
(1) an open interior cup shaped rotor coaxially aligned with the rotatable shaft;
(2) flexural mounting means attached at one end to the shaft and rotatable therewith, and having a cylindrical opening at the other end adapted to receive said rotor;
(3) connecting means joining the peripheral edge of said rotor to said other end of said mounting means permitting said rotor limited rotational movement about a first axis orthogonal to the spin axis;
(4) magnetic means disposed in the interior of the cup of said cup shaped rotor; and
(5) torquer coil means fixed to the frame but extending into the cup interior adjacent to said magnetic means and operable therewith for maintaining rotor rotation in a plane orthogonal to the spin axis,
whereby said flexural mounting means is accessible for balancing and adjusting means with the instrument otherwise assembled and operable.

### Claim 17 (depends on 16)

The inertial instrument of claim 16 wherein said flexural mounting means permits said rotor limited rotational movement about a second axis, orthogonal to said first axis and to the spin axis.

### Claim 18 (depends on 17)

The gyroscope of claim 17 wherein said torquer coil means include a first pair of coils positioned to apply restoring torques about said first axis and a second pair of coils positioned to apply restoring torques about said second axis.

### Claim 19 (depends on 16)

The gyroscope of claim 16 wherein said magnetic means include at least a first disc shaped permanent magnet polarized in a direction parallel to the spin axis.

### Claim 20 (depends on 19)

The gyroscope of claim 19 wherein said magnetic means further include second and third disc magnets, respectively, adjacent said first disc magnet, polarized in a direction parallel to the spin axis and having similar poles adjacent said first magnet for directing the flux in a direction substantially orthogonal to the spin axis, whereby the flux path is directed through said torquer coil means.

### Claim 21 (depends on 16)

The gyroscope of claim 16 wherein said magnetic means include a bar magnet having an axis orthogonal to the spin axis.

### Claim 22 (depends on 21)

The gyroscope of claim 21 wherein said torquer means include a concentric coil positioned in the interior of the cup between the cup wall and said magnetic means.

### Claim 23

In an improved, dynamically tuned gyroscope including a housing, motor means fixed to the housing, a shaft coupled to the motor and rotatable about a spin axis, means for sensing attitude of a rotor and means for torquing a rotor:
(a) a cup shaped rotor coaxially aligned with the rotatable shaft; and
(b) suspension means external to said cup shaped rotor for symmetrically connecting said rotor to the shaft.

### Claim 24 (depends on 23)

The gyro of claim 23 further including permanent magnet means disposed in the interior of said cup shaped rotor and the means for torquing extend into the interior of said cup shaped rotor between said permanent magnet means and the rotor wall for interacting with said magnet means.

### Claim 25 (depends on 24)

The gyro of claim 24 wherein said permanent magnet means includes at least one disk magnet polarized axially and mounted concentrically within said cup shaped rotor.

### Claim 26 (depends on 24)

The gyro of claim 24 wherein said permanent magnet means includes at least one bar magnet mounted in said cup shaped rotor.

### Claim 27 (depends on 26)

The gyro of claim 26 wherein the means for torquing includes a circular coil concentric with the spin axis and which extends into said cup shaped rotor between said bar magnet and cup wall, for interacting with said bar magnet.

### Claim 28 (depends on 23)

The gyro of claim 23 wherein the shaft and suspension are fabricated from a single piece of material and are permanently attached to each other.

### Claim 29 (depends on 23)

The gyro of claim 23 wherein the shaft is coupled to the motor means with bearings and where the bearing inner races and shaft are fabricated from a single piece of material and are permanently attached to each other.

### Claim 30 (depends on 23)

The gyro of claim 23 further including a header mounted at one end of the gyro next adjacent said cup shaped rotor to feed electrical signals through the housing.

### Claim 31

In an improved accelerometer including a housing, a means for sensing the attitude of an inertial mass element, means of torquing the inertial mass element, and a central axis:
(a) a cup shaped inertial mass element coaxially aligned with the central axis of the accelerometer; and
(b) suspension means external to said cup shaped inertial mass element, and symmetrically connected thereto for permitting rotation about an axis orthogonal to the central axis, the center of gravity of said inertial mass element being displaced axially from center of said suspension means.

### Claim 32 (depends on 31)

The accelerometer of claim 31 wherein permanent magnet means are disposed in the interior of said cup shaped inertial mass element and the means for torquing extend into the interior of said cup shaped inertial mass element between said permanent magnet means and the cup wall for interacting with said magnet means.

### Claim 33 (depends on 32)

The accelerometer of claim 32 wherein said permanent agnet means includes at least one disk magnet polarized axially and mounted concentrically within said cup shaped inertial mass element.

### Claim 34 (depends on 32)

The accelerometer of claim 32 wherein said permanent magnet means include at least one bar magnet whose magnetic axis is orthogonal to the central axis, mounted in said cup shaped inertial mass element.

### Claim 35 (depends on 34)

The accelerometer of claim 34 wherein the means for torquing includes a circular coil concentric with the central axis and which extends into said cup shaped inertial mass element between said bar magnet and cup wall, for interacting with said bar magnet.

### Claim 36 (depends on 31)

The accelerometer of claim 31 wherein said suspension means and the housing are fabricated from a single piece of material and are permanently attached to each other.

### Claim 37 (depends on 31)

The accelerometer of claim 31 further including a header mounted at one end of the accelerometer next adjacent said cup shaped inertial mass to feed electrical signals through the housing.

### Claim 38

In an improved single axis accelerometer including a housing, a central axis, means for sensing the attitude of an inertial mass element and means for torquing an inertial mass element:
(a) a cup shaped inertial mass element coaxially aligned with the central axis; and
(b) suspension means external to said cup shaped inertial means element and symmetrically mounted thereto for enabling rotation about an axis orthogonal to the central axis, the center of gravity of said inertial mass element being displaced radially from the center of said suspension.

### Claim 39 (depends on 38)

The accelerometer of claim 38 wherein permanent magnet means are disposed in the interior of said cup shaped inertial mass element and the means for torquing extend into the interior of said cup shaped inertial mass element between said permanent magnet means and the cup wall for interacting with said magnet means.

### Claim 40 (depends on 39)

The accelerometer of claim 39 wherein said permanent magnet means include at least one disk magnet polarized axially and mounted concentrically within said cup shaped inertial mass element.

### Claim 41 (depends on 39)

The accelerometer of claim 39 wherein said permanent magnet means include at least one bar magnet whose magnetic axis is orthogonal to the central axis mounted in said cup shaped inertial mass element.

### Claim 42 (depends on 41)

The accelerometer of claim 41 wherein the means for torquing includes a circular coil concentric with the central axis and which extends into said cup shaped inertial mass element between said bar magnet and cup wall, for interacting with said bar magnet.

### Claim 43 (depends on 38)

The accelerometer of claim 38 wherein said suspension means and housing are fabricated from a single piece of material and are permanently attached to each other.

### Claim 44 (depends on 38)

The accelerometer of claim 38 further including a header mounted at one end of the accelerometer next adjacent said cup shaped inertial mass element to feed electrical signals through the housing.