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Description
The Princeton Scientific Instruments Automatic Muzzle Reference System
(AMRS)* accurately measures the angular motion of the muzzle of a tank
mounted cannon relative to its trunnion at any elevation angle, while the
tank is in motion and as the round exits the muzzle. This instrument can
continuously measure muzzle pitch and yaw with a dynamic range of ±5
milliradians and precision of 5 microradians at a bandwidth of 1000 Hz. The
Princeton Scientific Instruments AMRS has used to evaluate tank cannon,
ammunition, and fire control concepts, and will be incorporated in future
tank and artillery fire control systems.
The basic approach taken to measure cannon
muzzle angular motion on a moving tank is based on viewing
the muzzle from the cannon trunnion. The optics assembly
consists of an autocollimator type instrument mounted
on the trunnion of the gun and a mirror rigidly fastened
to the muzzle. A beam of light projected by the autocollimator
telescope reflects off the muzzle mirror and passes
back through the telescope to be reimaged on a solid
state position sensitive detector located in the focal
plane. The output of the electronics are analog signals
representing muzzle azimuth and elevation.
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| Figure 1 |
Figure 1 shows data taken at Aberdeen Proving
Ground by the AMRS instrument while mounted on an M1A1
tank traveling over a rough terrain "washboard"
course at a speed of 25mph. The graph shows a small
sample of the data set plotted sequently in time on
a grid where the x and y axis are scaled in milliradians
and represent the horizontal and vertical components
of the muzzle pointing angle, respectively. Each data
point displayed represents a measurement by the AMRS
of the pointing angle of the cannon relative to the
trunnion. The data clearly shows the intricate meanderings
of the muzzle over time. The range of angular motion
for this test was found to be on the order of 3 milliradians.
The scale for the grid in Figure 1 is in milliradians.
A milliradian is 1 meter at 1000 meters. The capability
to continuous follow the motion of the tank cannon muzzle
to within fractions of a milliradian as shown in this
film significantly increases the probability of hitting
a tank sized target several thousand meters away.
The Princeton Scientific Instrument's AMRS
can monitor muzzle motion while the cannon is firing.
The ability of the AMRS to continuously monitor muzzle
pointing can yield information to the ballistics researcher
concerning the dynamics of the gun tube and ammunition,
and allow ammunition test results to be corrected for
muzzle pointing angle variation on a shot by shot basis.
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| Figure 2 |
Figure 2 displays two graphs showing the
muzzle pointing angle during 2 separate test firings
of the tank cannon. The round in the plot on the left
was actually fired a half hour later than the round
on the right. The general path the muzzle takes is similar
for both rounds. More importunately, the muzzle angle
at shot exit, indicated by the yellow data point, is
nearly the same for both shots. The significance of
this is the possibility of using pointing angle information
gained at shot exit from one firing of the cannon as
a predictor to the pointing angle at shot exit for the
second firing. This information could be incorporated
into the ballistic solution for aiming the second round,
significantly improving its accuracy.
The Princeton Scientific Instrument's Automatic
Muzzle Reference System can enhance the firing accuracy
of the M1A1 under all firing conditions, providing the
capability to continuously correct for bending of the
tank cannon due to tank motion, thermal heating, and
firing of ammunition.
* Note that Automatic Muzzle Reference System (AMRS), Continuous Muzzle
Reference System (CMRS), and Dynamic Muzzle Reference System (DMRS) are
synonymous. |
