Nonorthogonal sensor configuration using six single-degree-of-freedom inertial reference gyroscopes and a complete data processing and self-contained failure detection-and-isolation mechanism provides redundant capabilities to guidance and navigation systems. This system has been formulated in a strap-down configuration to attain maximum redundancy

Gilmore, J. P.

English

NASA Technical Reports Server

November 1967	 Brief 67-10433 
.
	
NASA T E CH BRIEF 
_1a 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Conceptual Nonorthogonal Gyro Configuration for Guidance and Navigation 
.,
Future extended space missions and supersonic 
transport applications will require guidance and 
navigation systems of high reliability. To achieve this, 
some form of redundancy will have to be employed. 
An investigation has been made into the use of non-
orthogonal sensor configurations to provide such 
redundant capabilities. An optimal configuration 
using six single-degree-of-freedom inertial reference 
gyroscopes has been defined and analyzed. The gyro-
scope input axes are arrayed in a unique symmetrical 
pattern that corresponds to the array of normals to the 
faces of a regular dodecahedron. 
A complete data processing and self-contained fail-
ure detection-and-isolation .mechanism has been 
defined for this symmetrical configuration. The data 
reduction technique permits satisfactory system per-
formance even with three of the six gyros inoperative. 
When more than three gyros are operative, a statisti-
cal weighting procedure has been implemented to 
define a "best" estimate of vehicle rates. A minimum 
computational processing technique has also been de-
fined. 
The failure-isolation mechanism operates on the 
basis of gyro output comparisons, and provides the 
data processing scheme with reorganization capabili-
ties. Isolation of any two failures and detection of the 
presence of a third is achieved for either instrument
performance degradation or catastrophic failures. 
This system has been formulated in a strap-down 
configuration to attain maximum redundancy, and 
analysis indicates an appreciable improvement in 
reliability over orthogonal redundant guidance system 
configurations, including those employing nine gyros. 
The concepts formulated in this study are also directly 
applicable to other inertial instruments. 
Notes: 
1. This development is in conceptual stage only, and 
as of date of publication of this Tech Brief, neither 
a model nor prototype has been constructed. 
2. Inquiries concerning this invention may be di-
rected to:
Technology Utilization Officer 
Manned Spacecraft Center 
Houston, Texas 77058 
Reference: B67-10433 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source: Jerold P. Gilmore

of Massachusetts Institute of Technology

under contract to

Manned Spacecraft Center

(M SC- l 1363) 
Category 01 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
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Conceptual nonorthogonal gyro configuration for guidance and navigation

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