# US 4,395,922 A · Gimballed stabilization system with means for suppression of dither characteristics

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- Number: US 4,395,922 A
- Document ID: US4395922A
- Status: Granted
- Kind: A
- Application number: 06/231,304
- Filed: 1981-02-04
- Granted: 1983-08-02
- Earliest claimed: 1981-02-04
- Assignees: The Charles Stark Draper Laboratory, Inc.
- Inventors: Philip N. Bowditch; James E. Negro
- Web page: https://patentgrep.com/patent/US4395922A

## CPC

- G01C 21/18: Stabilised platforms, e.g. by gyroscope
- G01C 19/04: Details
- Y10T 74/1254: by motor torque
- Y10T 74/1261: with pick off
- Y10T 74/1275: Electrical
- Y10T 74/1293: Flexure hinges for gyros
- 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

A gimballed platform stabilization system includes at least one outer member, an inner member, and an intermediate inertia bearing member. The intermediate member has limited coaxial angular freedom about an isolation axis with respect to the inner and outer members. A limited freedom (about the isolation axis) torsional flexure element is coupled between the intermediate and inner members. A first servo loop establishes a "negative spring rate" in parallel with the positive spring rate associated with the flexure element, maintaining a low net effective spring force on the inner member. A second servo loop prevents the angular excursion between the intermediate member and the inner member to extend beyond the limits of the flexure element. This inertia reaction stabilization configuration reduces disturbing torques from a stabilization axis to non-linear spring residuals which are relatively small.

## Claims

### Claim 1

A gimballed system for stabilizing an inner members with respect to an outer member about at least one axis, comprising:
A. an outer member,
B. an intermediate member, said intermediate member being rotationally coupled about said axis to said outer member,
C. an inner member
D. a torsional flexure and associated means for coupling said flexure between said intermediate member and said inner member along said one axis,
E. first torquer means for torquing said inner member with respect to said intermediate member about said one axis in response to a first control signal,
F. second torquer means for torquing intermediate member with respect to said outer member about said one axis in response to a second control signal,
G. flexure angle sensor means for generating an angle signal representative of the angular displacement of said inner member with respect to said intermediate member about said one axis,
H. platform sensor means for generating an angular position signal representative of the angular position of said inner member about said reference axis, and
I. control network including means for generating said first control signal, said first control signal being proportional to the sum of said angle signal and said angular position signal, and further including means for generating said second control signal, said second control signal being proportional to said angle signal.

### Claim 2 (depends on 1)

A system according to claim 1 wherein said intermediate member is characterized by a relatively large moment of inertia about said axis.

### Claim 3 (depends on 1)

A system according to claim 1 wherein said platform sensor means includes an integrating gyro.

### Claim 4 (depends on 1)

A system according to claim 1 wherein said platform sensor means includes a rate gyro and an associated integrating network.