Study explains the basic concept of pulse-rebalanced inertial instruments in terms of an idealized model which performs the processes of integration, prediction and quantization. An analytical model of an actual pulse-rebalanced instrument was derived in a form comparable to the idealized system

Lory, C. B.

English

NASA Technical Reports Server

July 1969
	
Brief69-10216 
NASA TECH BRIEF 
NASA Teèh 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. 
Compensation of Pulse-Rebalanced Inertial Instruments 
.
n
A study has been carried out to formulate a sound 
theoretical basis for designing and evaluating pulse-
rebalanced instruments (and the associated compen-
sating networks), such as pulse-rebalanced integrating 
accelerometers and gyroscopes with periodic error 
sampling. A particular difficulty in the design of such 
instruments is the analysis of nonlinear instabilities in 
the rebalance loop. A further complication is the use 
of sampling introduced primarily because the precise 
control of pulse width to maintain a stable torque 
scale factor requires that the detection and switching 
be synchronized with a crystal clock. 
The basic concepts of pulse-rebalanced inertial in-
struments are explained in terms of an idealized model 
which performs the processes of integration, predic-
tion, and quantization. The ideal quantizer contains a 
step discontinuity and a periodic sampler with feed-
back through a zero-order hold and an integrator. The 
quantizer may follow binary or ternary switching laws. 
An analytical model of an actual pulse-rebalanced 
instrument was derived in a form comparable to the 
idealized system. A novel approach was used to provide 
criteria for designing a cascade filter to ensure linear
separation of signal and noise. The combination of a 
linear ramp function (over a short time interval) and 
the cascade filter is parallel-compensated to achieve 
ideal quantizer characteristics. An analytical example 
is outlined, suggesting a possible application of the 
theory, using simple circuitry, to compensate a pulsed, 
inertial reference integrating gyroscope developed by 
the M.I.T. Instrumentation Laboratory. 
Note: 
Documentation is available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: TSP69- 10216 
Patent status:. 
No patent action is contemplated by NASA. 
Source: C. B. Lory of 
The Massachusetts Institute of Technology 
under contract to 
Manned Spacecraft Center 
(MSC-13098) 
Category 01 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19690000216 2020-03-16T17:41:25+00:00Z


Compensation of pulse-rebalanced inertial instruments

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server