U.S. patent application number 11/581506 was filed with the patent office on 2008-08-28 for accuracy fuze for airburst cargo delivery projectiles.
This patent application is currently assigned to KDI Precision Products, Inc.. Invention is credited to Michael F. Steele.
Application Number | 20080202324 11/581506 |
Document ID | / |
Family ID | 32850099 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080202324 |
Kind Code |
A1 |
Steele; Michael F. |
August 28, 2008 |
ACCURACY FUZE FOR AIRBURST CARGO DELIVERY PROJECTILES
Abstract
In one aspect, an artillery projectile apparatus is provided
that includes a carrier projectile containing a payload, and a fuze
disposed at an ogive of the projectile and which is configured to
eject the payload when the fuze is detonated. The fuze includes a
receiver configured to receive location information from a
radionavigation source and a processor configured to acquire
position data from the receiver. The processor is also configured
to estimate a projectile flight path using the position data, to
determine intercept parameters of the artillery projectile relative
to an ejection plane of its payload cargo, and to adjust an
ejection event initiation command time of the payload in accordance
with the determined intercept parameters. In some configurations,
the present invention dramatically decreases range errors typically
associated with delivering artillery payloads to specific
targets.
Inventors: |
Steele; Michael F.;
(Cincinnati, OH) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
KDI Precision Products,
Inc.
|
Family ID: |
32850099 |
Appl. No.: |
11/581506 |
Filed: |
October 16, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10368112 |
Feb 18, 2003 |
7121210 |
|
|
11581506 |
|
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Current U.S.
Class: |
89/1.11 ;
102/214; 102/215; 102/489 |
Current CPC
Class: |
F42B 12/58 20130101 |
Class at
Publication: |
89/1.11 ;
102/489; 102/214; 102/215 |
International
Class: |
F42B 12/58 20060101
F42B012/58 |
Claims
1. A method for delivering an artillery projectile payload to a
target, said method comprising: determining a cargo ejection plane
between a gun firing the artillery projectile and the target and a
nominal ejection event initiation command time to deliver the
artillery projectile payload to the target; firing the artillery
projectile at the target; acquiring, at the artillery projectile
after firing, position and time of flight data of said projectile;
using derived position data and time of flight data to predict a
time of intercept and altitude; and adjusting, at the artillery
projectile after firing, ejection event initiation command time of
the artillery projectile payload in accordance with the acquired
position and time data.
2. A method in accordance with claim 1, wherein said acquiring
position and time data comprises receiving global positioning
satellite (GPS) data using a receiver located at the artillery
projectile.
3. A method in accordance with claim 1, further comprising sampling
said GPS data at a variable rate during flight.
4. A method in accordance with claim 1, wherein said receiving GPS
data further comprises utilizing an antenna for a high-spin-rate
projectile.
5. A method in accordance with claim 1, wherein said adjusting
ejection event initiation command time comprises adjusting the
ejection event initiation command time utilizing a processor at the
artillery projectile.
6. A method in accordance with claim 1, further comprising updating
nominal ejection plane intercept parameters following acquisition
of a GPS data set.
7. A method in accordance with claim 6, further comprising
performing convergence tests on the updated ejection plane
intercept parameters following acquisition of a GPS data set.
8. A method in accordance with claim 7, further comprising
conditioning said adjusting the ejection event initiation command
time upon results of the convergence tests, and utilizing a default
ejection event initiation command time in the event that the
convergence tests indicate a GPS anomaly.
9. A method in accordance with claim 1, wherein said adjusting
ejection event initiation command time of the artillery projectile
payload comprises predicting an elevation and time for the
artillery projectile to intercept the ejection plane and reducing
said predicted time if an ejection plane interception point is
higher than a determined nominal intercept point, and increasing
said predicted time if the ejection plane interception point is
lower than the determined nominal intercept point.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/368,112 filed on Feb. 18, 2003. The disclosure of the
above application is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a low cost munition fuze
having increased accuracy, and more particularly to a low cost
munition fuze having reduced projectile launch and flight
errors.
BACKGROUND OF THE INVENTION
[0003] Studies performed on the long-range accuracy of the current
U.S. Army artillery shell stockpile have suggested that at ranges
above 20 kilometers, numerous rounds must be fired to achieve a
lethal effect on the target. Area saturation can be used to defeat
or immobilize a target, at the costs of delaying advancing troops
from reaching the target and allowing an enemy some opportunity to
evade an assault. Additionally, conventional munition inaccuracies
require friendly fire target standoff distances of greater than 600
meters, which prevents suppressive fire in support of target
engagement by advancing troops for as much as 20 minutes.
[0004] Precision weapons are being developed to increase range, to
significantly reduce the conventional munition logistic task and to
resolve the battle engagement time and mobility issues. However,
precision weapons are expensive, and their high accuracy may not be
required for conventional munition ranges.
SUMMARY OF THE INVENTION
[0005] Some configurations of the present invention therefore
provide an artillery projectile apparatus that includes a carrier
projectile containing a payload, and a fuze disposed at an ogive of
the projectile and which is configured to eject the payload when
the fuze is detonated. The fuze includes a receiver configured to
receive location information from a radionavigation source and a
processor configured to acquire position data from the receiver.
The processor is also configured to estimate a projectile flight
path using the position data, to determine intercept parameters of
the artillery projectile relative to an ejection plane, and to
adjust an ejection event initiation command time of the payload in
accordance with the determined intercept parameters.
[0006] Various configurations of the present invention also provide
a method for delivering an artillery projectile payload to a
target. The method includes determining a cargo ejection plane
between a gun firing the artillery projectile and the target and a
nominal ejection event initiation command time to deliver the
artillery projectile payload to the target; firing the artillery
projectile at the target; acquiring, at the artillery projectile
after firing, position and time data; and adjusting, at the
artillery projectile after firing, ejection event initiation
command time of the artillery projectile payload in accordance with
the acquired position and time data.
[0007] Some configurations of the present invention also provide a
fuze that includes a fuze housing; fuze electronics including a
processor and a radionavigation receiver contained within the fuze
housing; and a power supply configured to power the processor and
the radionavigation receiver; an explosive charge responsive to the
processor. The processor is responsive to the radionavigation
receiver to adjust a time at which the explosive charge is
detonated.
[0008] It will be observed that configurations of the present
invention provide a more accurate alternative to conventional
munitions systems and a less expensive alternative to precision
munitions systems. In some configurations, the present invention
contains the artillery fuze functions, is profile-interchangeable
with NATO requirements as defined in MIL-Std-333B, and/or
incorporates technologically available smart munition updates.
[0009] Furthermore, it will be observed that some configurations of
the present invention provide low cost, mid-range accuracy
improvements that can reduce the number of deployed projectiles
needed to acquire a target. Some configurations also provide
additional cover fire protection to advancing troops by reducing
standoff distances and times owing to improved munition
accuracies.
[0010] Further areas of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0012] FIG. 1 is a cross-sectional drawing representative of
various configurations of an artillery projectile of the present
invention.
[0013] FIG. 2 is a partial cross-sectional drawing representative
of various configurations of a fuze of the present invention,
including a fuze configuration suitable for use in configurations
of the artillery projectile represented in FIG. 1.
[0014] FIG. 3 is a drawing showing the relationship of various
trajectories and ejection points relative to a nominal cargo
ejection plane and a target, where the trajectories intercept the
nominal cargo ejection plane at different heights.
[0015] FIG. 4 is a drawing showing the relationship of various
trajectories and ejection points relative to a nominal cargo
ejection plane and a target, where the trajectories intercept the
nominal cargo ejection plane at different angles.
[0016] FIG. 5 is a drawing indicating the increased payload
delivery accuracy achievable by various configurations of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] The following description of the preferred embodiment(s) is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses.
[0018] In some configurations and referring to FIG. 1, the present
invention comprises an artillery projectile 10 that comprises a
conventional carrier projectile 11 having a front head part or
ogive 12 and a rear base part 14. Carrier projectile 11 contains
one or more payloads such as grenades 18 that are configured to
detonate on a target. A fuze 22 is disposed at ogive 12 and is
configured to eject the payload when fuze 22 is detonated. In
particular, when fuze 22 is detonated, an expanding gas fills a
cavity 24 and forces piston 26 to press plate 28 rearward, forcing
payload or payloads 18 to push against base 14. Base 14 is thus
forced off carrier projectile 11 and payload or payloads 18 are
ejected from projectile 11. Payload(s) 18 are spin-deployed to
control payload dispersion during delivery. The operation and
construction of piston 26, plate 28, payload 18 and base 14 are
conventional and need not be described further.
[0019] Referring to FIG. 2, fuze 22 comprises an outer casing 30, a
fuze setter coil 32, circuit cards 34, a power supply assembly
including a battery 38, a safe and arm assembly 40, and a booster
cup 42. A lead charge 44 is configured to detonate booster pellets
46 in booster cup 42 in response to an ejection command from a
processor 48 residing on circuit cards 34. For safety, the ejection
command is preceded by two sensed launch commands in addition to an
adjusted firing time command from the processor. Fuze 22 in some
configurations is interface-equivalent with MIL-Std-333B
specifications. Fuze 22 has screw threads 52 for attachment at
ogive 12 of projectile 11.
[0020] In some configurations, a global positioning satellite (GPS)
receiver 50 is provided in fuze 22 to reduce range errors. Receiver
50 utilizes a ring antenna 36 encircling fuze 22 to receive signals
from GPS satellites (not shown). In another embodiment, another
GPS-receptive antenna suitable for use with a high-spin-rate
projectile could be used. Received GPS data from receiver 50 and
time are used by processor 48 to determine a flight trajectory and
to adjust payload ejection event initiation command timing for
increased range accuracy, for example, by reducing the effects of
temperature, gun lay, launch, firing charge, baseburner and
projectile flight range errors. In some configurations, to avoid
loss of a projectile, processor 48 defaults to a basic M762 fuze
mode with fixed ejection times in the event of a GPS subsystem
anomaly, such as jamming, inability to acquire satellite
transmissions, etc.
[0021] Under normal conditions, GPS data will be available, and
onboard processor 48 will use time data and the acquired GPS
position data to calculate a projectile flight path, and to predict
an intercept angle, height and time at which artillery projectile
10 will pass through a gun and target-defined ejection plane 62, as
represented in FIG. 3. Downrange distance traveled by the payload
18 from an ejection point is a function of the height or elevation
of the ejection point. A difference between an actual intercept
point and a nominal intercept point 64 of a nominal projectile
flight path 68 is determined and utilized to adjust an ejection
event initiation command time for ejecting cargo payload (e.g.,
grenade or other dispensable munitions 18). For example, if
artillery projectile 10 is more energetic than nominal, it would
follow a flight path such as flight path 72. In this case, the
ejection event initiation command time is adjusted so that ejection
occurs at a point 74 prior to interception of cargo ejection plane
62 and payload 18 follows path 78, rather than path 66, to target
60. If the projectile is less energetic than nominal, the ejection
event initiation command time is adjusted to eject payload 18 at a
point 76 after interception of flight path 70 of artillery
projectile 10, and payload 18 follows path 80 to target 60. These
timing adjustments thus effect a more accurate delivery of payload
18 to target 60.
[0022] In some configurations, a secondary range adjustment is made
by correcting the ejection event initiation command time of payload
18 in accordance with the trajectory slope. More particularly, and
referring to FIG. 4, if the actual trajectory slope 84 is steeper
and the forward or downrange velocity of the cargo at ejection is
less than would be the case with a nominal trajectory slope 68,
ejection event initiation command time is delayed so that payload
18 will impact target 60 by ejecting payload 18 at ejection point
86 and payload 18 follows descent path 92. On the other hand, if
the actual trajectory slope 82 is flatter than nominal trajectory
slope 68, the payload will be traveling downrange faster after
release than if the payload were following nominal slope 68.
Therefore, the ejection event initiation command time is advanced
so that ejection of payload 18 occurs at a point 88 before
trajectory slope 82 intersects cargo ejection plane 62. Payload 18
thus follows a path 90 that allows the payload to travel farther
downrange after ejection, and yet still hit at or near target
60.
[0023] Referring to FIG. 5, by providing a fuze with a first order,
or low cost one-dimensional range correction, a footprint
representing typical delivery errors to a target 60 is reduced from
a footprint 56 representing typical delivery errors in the absence
of correction to a reduced size footprint 58 representing the
delivery errors of a plurality of artillery projectile
configurations and delivery method configurations of the present
invention. Configurations of the present invention can be utilized
in conjunction with techniques for reducing deflection errors to
effect a two-dimensional correction and thus provide additional
accuracy.
[0024] In some configurations of the present invention, power
consumption is reduced by increasing the interval between GPS data
samples. The sampling intervals can pre-selected in accordance with
desired accuracy and power consumption levels, or may be varied
during flight in some configurations to obtain a satisfactory
trade-off between accuracy and power consumption. Estimated
projectile flight parameters may be utilized to adjust GPS sampling
intervals. For example, some 60-second projectile flights may
require between 6 to 10 samples to adequately estimate the ejection
time and trajectory intercept, although the number of samples
required may vary from flight to flight.
[0025] Some configurations of the present invention utilize the
following steps to hit a target with artillery projectile 10.
First, using spatial position finding devices, both the target and
the artillery projectile firing gun are located in
three-dimensional space. The fuze power on sequence is then
initiated. GPS gun and target location data and basic fuze
initialization data is input to the fuze using the fuze setter. A
typical configuration would accommodate turn-on, system
initialization, and data entry and/or update within twenty minutes
of the projectile firing.
[0026] An onboard processor 48 establishes, using target location
data inputs, a cargo ejection plane 62 that is perpendicular to an
azimuth range line between the gun and target 60. Cargo ejection
plane 62 is located up range from target 60 by a distance
determined to cause the deployed cargo grenades 18 to land on the
target when cargo grenades 18 are dispensed from a nominal flight
performance projectile 68. For example, in some configurations, a
nominal projectile flight path 68 intercepts cargo ejection plane
62 at a nominal flight path to ejection plane intercept angle
estimated at 52 degrees and at an estimated nominal height of burst
altitude of 500 m. Initially, processor 48 is programmed to utilize
data from GPS receiver 50 of fuze 22 to eject payload 18 when
projectile 10 Intercepts ejection plane 62. In some configurations,
the initialized intercept time is the same as the basic M762 set
time, and further the processor 48 is configured to use the
initialized intercept time as a default ejection event initiation
command time in the event of a GPS anomaly or a fuze processing
anomaly, thereby avoiding loss of the projectile.
[0027] After the fuze is programmed with target and gun location
data, the artillery projectile 10 is loaded and fired. During
flight, GPS receiver 50 acquires position and time data. Processor
48 is configured to use acquired GPS data to determine a deviation
for a nominal projectile flight path to predict an intercept angle,
height and time at which projectile 10 will pass through ejection
plane 62. As the flight of projectile 10 continues, ejection plane
intercept parameters are updated with each new GPS data set. A
convergence test, for example, can be performed following each new
set of intercept information to determine if a GPS anomaly has
occurred. A detected GPS anomaly causes processor 48 to default to
either the last predicted set of ejection plane intercept
parameters or to a typical conventional fuze set time. Processor 48
is configured to use either the last predicted ejection plane
parameters or a typical conventional fuze set time, dependent upon
the number of successful GPS updates before an anomaly occurs, in
the event such an anomaly occurs prior to ejection.
[0028] In some configurations, the intercept point of projectile 10
with ejection plane 62 can be predicted to an altitude of plus or
minus 12 m and a range of plus or minus 8 m. Once the ejection
plane intercept point is determined, a difference between the
nominal impact point and a predicted impact point is used to
enhance accuracy by adjusting the ejection event initiation command
time. For example, if the predicted ejection plane 62 intercept
point and time and nominal impact point 64 and time are coincident
then no correction to the ejection event initiation command time is
made and a nominal grenade decent trajectory 66 is used for the
payload or grenades 18 to impact target 60. However, if artillery
projectile 10 has higher velocity than a nominal artillery
projectile, the predicted cargo ejection plane 62 intercept point
94 will be higher than nominal cargo ejection intercept point 64.
Based on an elevation difference between cargo ejection intercept
points 64 and 94 and a difference between times corresponding to
points 64 and 94, the ejection event initiation command time is
reduced, thus moving the ejection point up range to a point 74 and
thereby adjusting payload 18 impact point to more closely coincide
with target 60. Similarly, if artillery projectile 10 has lower
velocity than a nominal artillery projectile, the ejection event
initiation command time is increased so that the payload or
grenades 18 are ejected at point 76 rather than at point 96,
thereby adjusting descending grenade 18 to impact the ground at a
point closely coinciding with target 60.
[0029] In some configurations, and referring to FIG. 4, a secondary
range error adjustment is made by correcting the payload ejection
event initiation command time for the artillery projectile
trajectory intercept angle and time with cargo ejection plane 62.
In this case, if projectile intercept trajectory 84 is steeper than
nominal intercept trajectory 68, the cargo ejection event
initiation command time, i.e. the intercept trajectory 84 time, is
delayed to allow payload 18 to fly further down range before
ejecting its payload at a point 86. This adjustment allows the
grenades to impact the ground at the target range. Similarly, if
projectile flight trajectory 82 is flatter than nominal intercept
trajectory 68, the timing is advanced to eject the payload or
grenades 18 at point 88, prior to interception of ejection plane 62
by trajectory 82.
[0030] In some configurations, the fuze 22 design may meet some or
all of the following specifications:
[0031] NATO Fuze Configuration, MII-Std-333B
[0032] Mil-Std-1316D with overhead safety (Arm 50-msec. prior to
Cargo Ejection)
[0033] M762S&A
[0034] Inductive set only with EPIAS (No hand set or
adjustment)
[0035] 20 minute ground set capability (No 10 day preset)
[0036] XM982 GPS jamming protection
[0037] M762 timing is default mode
[0038] Flight time 100 sec.
[0039] Accuracy 125 m circular error probability (CEP) at 35 km
with 2 hr. met. Data
[0040] No decrease in lethal area
[0041] Gun harden--20,000 g setback
[0042] Gun harden--20,000 rpm spin
[0043] 20 year shelf life
[0044] In some configurations, the profile of fuze 22 is identical
to the M762 profile and satisfies the NATO requirements as defined
in Mil-Std-333B. The front end of fuze 22 incorporates the same
plastic ogive and fuze setter coil 32 that is used on some
conventional configurations of M762 fuzes. The base of fuze 22 also
retains the basic M762 design. Booster cap 42 includes explosives
46, and lead charge 44. Safe and arm assembly and piston actuator
40 prevents arming until artillery projectile 10 is within 50 msec.
from payload 18 ejection.
[0045] Unlike conventional M762 fuzes, GPS receiver 50 with ring
antenna 36 may be provided on circuit boards 34 in fuze 22 and
processor 48 may be configured to take advantage of the information
received by receiver 50. In some configurations, a battery 38 is
provided to power fuze electronics, including GPS receiver 50 and
processor 48.
[0046] Some configurations of fuze 22 utilize three double-sided
circuit boards 34, which provide 16 square inches of component
mounting surface. GPS receiver 50 and trajectory analysis processor
48 require approximately 10 square inches of circuit board area.
Addition fuze electronics on circuit boards 34 utilize the GPS
receiver clock and therefore the safety functions and firing
circuits can be accommodated on 3 additional square inches of
circuit board. Thus, up to three square inches can be provided for
additional circuitry and functionality, if required.
[0047] Battery 38 can provide power for driving GPS receiver 50,
processor 34 and additional fuze circuitry for 20 minutes of ground
time followed a 2-second power initialization spike and then a
constant power drain for a 100-second flight period. A battery with
a volumetric configuration of 1.5 inches in diameter by 0.88 inches
high has sufficient capacity in some configurations, although other
battery configurations may also be used, depending upon cost and
performance requirements.
[0048] The center section of the configurations of fuze 22
represented by FIG. 2 feature axial conformal circuit boards 34
mounted in front of battery 38. The battery can be, for example, a
right circular cylinder positioned between safe and arm assembly 40
and circuit boards 34. Other configurations feature forward or aft
mounting locations for battery 38. Some configurations provide
stacked round circuit cards 34 instead of the conformal axial
circuit boards 34 shown in FIG. 2. A battery 38 and circuit card 34
configuration can be selected in accordance with dynamic
environment survival vs. assembly ease and component costs
requirements.
[0049] It will be thus observed that configurations of the present
invention provide a more accurate alternative to conventional
munitions systems and a less expensive alternative to precision
munitions systems. The above-described fuze provides improved
accuracy without depleting the spin of a deployed cargo. Because
deployment spin is conserved, a historical footprint of the cargo
can be preserved. Also, some configurations are
profile-interchangeable with the M762 fuze per MIL-Std-333B
specifications and some configurations incorporate technologically
available smart munition updates.
[0050] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the gist of
the invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *