DTIC ADA266694: Performance Evaluation of the Honeywell GG1308 Miniature Ring Laser Gyroscope

49 Pages·1.5 MB·English

by  Defense Technical Information Center

6 694
AD-A26
PERFORMANCE EVALUATION OF THE
HONEYWELL GG1308 MINIATURE
RING LASER GYROSCOPE
by
M.F. Vrmnins and L.D. Gallop
DTIC
S ~ELECTE Dl
JUL 14 1993
I
Thsdocumeftlt;;vft been approved
for public release and sale; its
dixt i us o uti@Dt -- -
DEFENCE RESEARCH ESTABLISHMENT OTTAWA
REPORT NO. 1166
Canad(cid:127)X
January19
CanaOttawa
. L93-15946
IILIIMINII
PERFORMANCE EVALUATION OF THE
HONEYWELL GG1308 MINIATURE
RING LASER GYROSCOPE
by
M.F. Vinnins and L.D. Gallop
Communications and Navigation Section
Electronics Divisio
DEFENCE RESEARCH ESTABLISHMENT OTTAWA
REPORT NO. 1166
PCN January 1993
041LJ Ottawa
ABSTRACT
This report describes the results of the performance
evaluation of a Honeywell GG1308 miniature Ring Laser
Gyroscope (RLG). The tests include turn-on and cold start,
bias drift, scale factor, scale factor linearity, thermal
transients and effects of dither compensation.
The gyroscope demonstrated excellent high-rate
performance although significant scale factor deviations
were noted during temperature variations. Instrument design
characteristics and areas of potential future investigation
are also discussed.
R9SUM*
Ce rapport d6crit les r~sultats de l'4valuation du
rendement d'un gyroscope A laser miniature, le module GG1308
de Honeywell. Les essais effectu~s incluent: la mise en
marche initiale, la d6rive de la polarisation, le facteur
d'6chelle, la lin6arit6 du facteur d'4chelle, les effets
transitoires et les effets de la compensation des
perturbations.
Le gyroscope a demontr6 un excellent rendement lors
d'essais A haut taux de changement anulaire et ce, malgr&
les d6viations importantes du facteur d'4chelle observ~es
lors de variations de temp6rature. Les caract6ristiques de
conception de 1'instrument et les possibilit~s d'6tudes
futures sont aussi discut~es.
Accesion For
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iii
EXECUTIVE SUMMARY
A Honeywell GG1308 miniature Ring Laser Gyroscope was
evaluated in the DREO Inertial Navigation Laboratory for
possible application in the design and development of a Low-
Cost Attitude and Heading Reference System (LCAHRS) for
drone/RPV and helicopter applications. The original LCAHRS
concept was derived from a study conducted by Honeywell ATC
in Canada for DREO. The purpose of the study was to
investigate the AHRS requirements of several RPV's and other
UAV's and, through simulation, evaluate the potential of the
newly-developed Honeywell GG1308 gyroscope to meet these
requirements. A GG1308 gyroscope was procured by DREO for
in-house evaluation for comparison with predicted
performance.
The Honeywell GG1308 is a single-axis Ring Laser
Gyroscope (RLG) featuring an equilateral triangular glass
block of 0.8 inch per leg (a total laser effective path
length of 2.4 inches). The instrument construction employs
simple, inexpensive techniques intended to produce a low
performance instrument for stabilization and control
applications where low cost and small size are required. A
GG1308 gyroscope was delivered to DREO in mid-1990 and
evaluations were carried out from November 1990 to April
1991.
Results of the testing showed that instrument
performance at high angular rates was better than
specifications although significant scale factor deviations
were noted during temperature variations. This deviation
may limit applications to lower-accuracy systems unless
temperature compensation is employed. The gyroscope met
most performance specifications over a rate range of ±1000
deg/sec.
Areas of future interest include characterization of
low rate performance and performance in a vibration
environment.
V
TABLE OF CONTENTS
ABSTRACT . ... iii
EXECUTIVE SUMMARY ................... V
TABLE OF CONTENTS .................. vii
1.0 INTRODUCTION .i.................................1-1
1.1 BACKGROUND ............................... 1-1
1.2 THE HONEYWELL GG1308 GYROSCOPE ..... ...... 1-1
1.3 GG1308 PERFORMANCE SPECIFICATIONS ..... 1-3
1.4 SUPPORT ELECTRONICS ...... ............ 1-3
2.0 GG1308 DATA OUTPUT DESCRIPTION .......... . . . 2-1
2.1 OUTPUT FORMAT ....... ............... .. 2-1
2.2 DATA RECORDING ......... .............. 2-1
2.3 GRAPHICAL REPRESENTATION ... ......... 2-3
3.0 DREO TEST FACILITY ........ ............... 3-1
3.1 DREO INERTIAL NAVIGATION LABORATORY . . .. 3-1
3.2 TEST FIXTURING AND ALIGNMENT .. ....... 3-1
4.0 TEST PROGRAM ............ .................. 4-1
4.1 HISTORICAL ............................... 4-1
4.2 TEST PROCEDURES ........ .............. 4-1
4.2.1 Turn-On/Cold Start .. ....... 4-1
4.2.2 Bias Drift ..... ........... 4-1
4.2.3 Scale Factor ..... .......... 4-3
4.2.4 Scale Factor Linearity ..... 4-3
4.2.5 Thermal Transient .......... .. 4-3
4.2.6 Dither Compensation ......... .. 4-3
4.3 DATA REDUCTION ........................... 4-4
5.0 TEST RESULTS ............ .................. 5-1
5.1 HONEYWELL TEST DATA ........ ........ 5-1
5.2 DREO TEST RESULTS...............................5-1-
5.2.1 Turn-on Transient/Cold Start . 5-1
5.2.2 Bias Drift ........ .......... 5-2
5.2.3 Scale Factor... . . .. ..... 5-2
5.2.4 Scale Factor Deviation'. .... .. 5-2
5.2.5 Thermal Transients .. ....... 5-7
5.2.6 Temperature .... ........... 5-8
5.2.7 Dither Compensation ......... .. 5-8
5.2.8 Summary ...... ............. 5-8
6.0 CONCLUSIONS ................................... 6-1
6.1 EVALUATION OF RESULTS .... ........... 6-1
6.2 GENERAL COMMENTS ....... ............. 6-1
REFERENCES ....................................... REF-I
vii
1.0 INTRODUCTION
1.1 BACKGROUND
This report describes the results of the performance
evaluation of a Honeywell GG1308 miniature Ring Laser
Gyroscope (RLG). This instrument was developed for use in
low-cost, non-precision applications. In particular, DREO
was interested in the development of a Low-Cost Attitude and
Heading Reference System (LCAHRS) for drone and Remotely
Piloted Vehicle (RPV) applications. A paper study was
conducted for DREO by Honeywell Advanced Technology Centre
(ATC) in Canada investigating LCAHRS requirements for
various vehicles. The Inertial Navigation Laboratory at
DREO was then used to evaluate a GG1308 gyroscope to
determine suitability for the LCAHRS application.
This report describes the gyroscope design, test
facilities, test procedures and the results obtained.
1.2 THE HONEYWELL GG1308 GYROSCOPE
The Honeywell GG1308 miniature ring laser gyroscope
(RLG) is a single-axis angle sensor consisting of a ring
laser assembly, a dither motor and gyro-critical electronic
circuitry all contained within a sealed housing. A drawing
of the ring laser assembly is shown in Figure 1-1. [I]
It features an equilateral triangular glass block of
0.8 inch per leg (hence the Honeywell designation 1308; the
last two digits being the leg length, in inches, of the
laser cavity). On the glass block, made of a material
designated BK-7, are mounted one path length control (PLC)
transducer mirror, a readout wedge mirror and a curved
mirror. In addition, there are three electrodes (two
cathodes and one anode/fill tube) attached to the block with
glass frit seals. The block cavity is filled with a mixture
of Helium and Neon gases and is operated on the 0.6328 gm
transition of Neon.
After cold-weld pinchoff of the fill tube electrode, a
PLC driver is bonded to the transducer mirror, a PLC sensor
is attached to the curved mirror and a readout sensor is
attached to the readout wedge mirror. A microcircuit
temperature sensor, a start-assisting, high-intensity light
emitting diode and an interconnect Printed Wring Board (PWB)
are mounted to the glass block. The ring laser assembly has
an effective path length of 2.4 inches and is mechanically
dithered about its input axis to minimize the non-
linearities of lock-in at low input rates.
1-1
POWER SENSOR
r.-,...(FOR PATHLENGTH CONTROL)
.,-.CURVE MIRROR
CATHODE
CATHODE -- LASER BLOCK
READOUT DETECTOR
ANODE W/PHASE MASK
READOUT MIRROR/WEDGE
'4 ----'- -0,8"-- -- '
FIGURE 1-1 GG1308 RING LASER GYRO ASSEMBLY
1-2
The GG1308 gyroscope is unique in several ways in that
it is a low performance instrument designed for
stabilization and control applications where low cost and
small size are required. The instrument design was totally
cost-driven with the expressed intent of a final cost of
less than $1,000 in production quantities. To achieve this,
several innovative technologies have been employed and will
be briefly described here because they impact upon the final
performance of the gyroscope and results will be related
back to these technologies later in this report.
In the past, gyro blocks have been made of a material
with a very low coefficient of thermal expansion, such as
Zerodur or Cervit glass ceramics, and components such as the
mirrors and electrodes have been sealed to the block by
precision polishing and bonding techniques.
The glass-frit technology permits small low-
performance gyros to be made at far lower cost. Glass-frit
bonding allows for the use of materials with large
coefficients of thermal expansion. The frit process is used
to seal the mirrors and electrodes to the solid BK-7 glass
laser block. These parts are pasted to the glass block with
a fine glass powder in a liquid or paste binder, and held
mechanically in place. The assembly is then heated to a
very high temperature. The binder evaporates and the glass
powder melts, producing a strong vacuum-tight seal. As a
result, a major concern is the performance of this gyro when
it is subjected to temperature variations. The scale factor
will vary with temperature because the gyro block expands as
the temperature increases thus changing the laser path
length. This effect is much larger in the GG1308 than in
gyro models made of low-expansion materials. Resulting
performance must be enhanced by thermal modelling and data
compensation.
1.3 GG1308 PERFORMANCE SPECIFICATIONS
Performance specifications for the Honeywell GG1308
ring laser gyro are contained in Table 1-1. Note that the
operating life, specified as 22000 hrs, is defined as "time
during which the gyro is economically repairable".
A photograph of the gyroscope is shown in Figure 1-2.
1.4 SUPPORT ELECTRONICS
In addition to the gyroscope and it's internal
electronics, a substantial amount of support electronics and
data processing is required to obtain useable "inertial"
data from the device.
1-3
Specification
"*B ias Stability: 10/hour
"*R andom walk: 0.1250/Vhour
"*R esolution: 11.17 arc secs/pulse
(2.79 arc secs/pulse
available)
"*S cale factor
- Value: 116,000±200 pulses per
revolution
- Error, all causes: 50 ppm (la)
"*I nput axis
- Alignment: 2 mradians
- Repeatability: 50 Aradians (1a)
"*R ate capability: ±10000/second
"*B andwidth: >500Hz
"*M echanical dither frequency: 900Hz min, 1550 Hz max
"*S tarting time: <500 mseconds
"*G -sensitive drift: Inherently insensitive
to acceleration
effects
"*A cceleration: >100g sustained
"*O perating temperature: -65OF to +180OF
"*S ignal outputs: Digital pulses for
clockwise and
counterclockwise
rotation
"*S helf life: >i0 years
"*O perating life: Ž2000 hrs*
Size, Weight and Power
Ring Laser Gyro
"*L ength: 1.5 inches
"*D iameter: 1.6 inches
"*W eight: 2.3 ounces
"*S ensor power: 0.9 watts
Sensor electronics single axis (packaged
to requirements)
"*V olume: <2 cubic inches
(typical)
"*B oard area (surface mount): 4 square inches
"*W eight: 2.5 ounces (typical)
"*I nput power: 2.3 watts (including
sensor)
* Repairable Life
TABLE 1-1 GG1308 PERFORMANCE SPECIFICATIONS [2]
1-4
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