US20080169609A1

US20080169609A1 - Thermal signature target form

Info

Publication number: US20080169609A1
Application number: US11/935,396
Authority: US
Inventors: Jonathan Mark Hetland
Original assignee: FATS Inc
Current assignee: Inveris Training Solutions Inc
Priority date: 2007-01-17
Filing date: 2007-11-05
Publication date: 2008-07-17

Abstract

A three-dimensional molded thermal signature target form comprising a conductive polymer material suitable for conducting infrared radiation such that a thermal signature is created and viewable by any number of suitable IR imaging or viewing systems. The thermal signature target form includes embedded busbars attached to a power source. The thermal signature target form can provide a realistic, inexpensive and safe live-fire target for training in thermal image recognition and shooting.

Description

RELATED APPLICATION

This application claims the benefit of priority of U.S. provisional application Ser. No. 60-885,266, filed Jan. 17, 2007, which is relied on and incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to a thermal signature target form.

BACKGROUND OF THE INVENTION

Today's military and police forces train with modern weapons systems requiring live-fire targets which accurately simulate the thermal signature of battlefield threats. At this time, there are a number of thermal signature simulation technologies which can be added to or act upon a conventional target panel or form. In general, these technologies require that separate thermal simulation elements be added to an existing target panel or form. Military or police organizations have a need for a high-performance, low-cost thermal target for use during live-fire training exercises.
A number of existing technologies have been reviewed to determine their manufacturability and cost competitiveness. The factors used to determine the best option for thermal signature simulation technologies include cost, thermal signature performance, live-fire performance, durability, efficiency, and ease of use. Current state-of-the-art thermal target technologies as well as infrared (“IR”) radiation and heater system technologies include multiple varieties of thermal applications intended to be joined to an existing target panel or form. In particular, U.S. Pat. No. 5,516,113 describes a screen printed ink matrix technology that has possible alternate thermal heating applications and was one of the many technologies reviewed. Initial analysis of this matrix technology showed that it may not be competitive in the thermal target market. Further, the screen printed ink matrix technology lacks a sturdy, durable form rendering it unsuitable to repeated projectile impacts during live-fire training exercises. The matrix technology also requires a separate step of attaching the printed ink matrix onto an existing target panel or form. This requires extra setup and breakdown time and negatively impacts usability considerations. Finally, the two-dimensional target is not lifelike and thus presents a less than realistic target for training purposes.
Current state-of-the-art thermal signature targets, including those available from TVI Corporation, consist of a foil or film which may be assembled into some form of a blanket module (e.g., U.S. Pat. Nos. 4,422,646, 4,546,983, 4,659,089). Foils and films lack durability and can be damaged or destroyed by foul weather or when struck by projectiles during a live-fire exercise. Blanket modules are mechanically secured to an existing target panel or form using tape, staples, or other manual fastening means, a time-consuming process that also decreases the uniformity of the targets. Further, during live-fire exercises, loosely attached blanket modules can move, deform, or become unattached after being struck by multiple bullets or other projectiles. This can cause a degradation in the thermal signature of the target, forming patchy or otherwise distorted thermal signatures.
U.S. Pat. No. 5,961,869 describes a radiant floor heating system product which utilizes a plastic heating element comprising an elongate web of flexible, electrically conductive plastic. This heating system utilizes a latex-based pressure sensitive adhesive to insulate the heating element and to fasten the heating element to a flooring substrate. Such an insulating adhesive renders the device difficult to transport on and off a military training ground since the device tends to adhere to surfaces that it contacts. In addition, the device emits a very large amount of heat, consuming copious amounts of energy and also rendering it unsuitable for simulating targets with lower amounts of emitted IR radiation. Finally, the floor heating system cannot be readily molded to form realistic three-dimensional shapes.
Other thermal signature technologies include electrically conductive wire mesh matrices, electrically conductive foil, electrically conductive spray, wire impregnated fiberglass, heating cables, heating beds, hot water jackets, hot water bottles, IR emitters, heated air, reverse-polarity reflector sheets, IR laser pattern generators, and conductive plastics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a molded thermal signature target form in accordance with the invention.

FIGS. 1 a-1 d are perspective views of molded thermal signature target forms in accordance with the invention.

FIG. 2 is a perspective view of a molded thermal signature target form in accordance with the invention.

FIGS. 3-4 are front elevational views of molded thermal signature target forms in accordance with the invention.

FIG. 5 is an infrared-spectrum thermal image of a prototype thermal signature target form prior to live-fire testing.

FIG. 6 is an infrared-spectrum thermal image of the prototype thermal signature target form of FIG. 5 following live-fire testing.

FIG. 7 is a visual-spectrum optical image of the prototype thermal signature target form of FIG. 5 following live-fire testing.

FIG. 8 is a visual-spectrum optical image of a standard three-dimensional infantry target following live-fire testing.

FIGS. 9-10 are flow charts illustrating exemplary methods of manufacturing a thermal signature target form in accordance with the invention.

DETAILED DESCRIPTION

With reference to FIG. 1 and FIGS. 1 a-1 d, a molded thermal signature target form 10 in accordance with an embodiment of the invention is illustrated. A thermal signature target form 10 comprises a conductive polymer material suitable for conducting infrared (IR) radiation such that a thermal signature is created and viewable by any number of suitable IR imaging or viewing systems. A pair of busbars 20 are embedded or attached to the outside edge 30 of the thermal signature target form 10, and the busbars 20 direct electrical current throughout the entire target form 10. When the thermal signature target form 10 is electrically energized, the resistance of the conductive polymer material creates heat, causing the target form 10 to emit infrared (IR) radiation which can be detected using suitable IR imaging or viewing systems. The busbars 20 can be attached to the thermal signature target form 10 by pre-molding grooves 40 into the target form 10 and embedding the busbars 20 in the grooves 40. The busbars 20 can also be mechanically attached by any means suitable for connecting or adhering a heat-conductive element to a conductive polymer material. The busbars 20 interface with a power supply 50 through weatherproof connectors 60 a, 60 b.
The thermal signature target form 10 described herein does not require that separate thermal stimulation elements be added to an existing target form. Instead, the target form 10 itself is formed to the desired three-dimensional shape such as a simulated enemy soldier (as shown in FIG. 1) or military tank or other vehicle (as shown in FIG. 2), using a conductive polymer material. The busbars 20 supply the necessary electrical stimulation to enable the conductive polymer material to emit the desired about of IR radiation.
In addition, in one embodiment, shown in FIG. 2, the three-dimensional target form 110 contains contours 170 in the surface of the conductive polymer material in order to vary the amount of IR radiation emitted from the thermal signature target form 110, producing a unique and realistic thermal signature. For example, thick contours 170 in the conductive polymer material of a simulated cannon barrel of a target form in the shape of a military tank could generate high levels of IR radiation due to the low resistance of the contours 170. These high levels of IR radiation at the cannon barrel of the simulated tank form 110 could mimic the thermal signature of an enemy tank that had just fired its main weapon. This could allow soldiers, for example, to learn to distinguish and interpret thermal signatures using their IR viewing equipment and fire upon simulated enemy tanks without the large costs involved when actual tanks or other military equipment are destroyed in training exercises.
In another embodiment of the invention, shown in FIG. 3, a plurality of busbar pairs 220 a, 220 b are embedded or attached to the outside edge 230 of the thermal signature target form 210, thus creating a plurality of voltage regions 280 a, 280 b in the thermal signature target form 210. Differing voltages are applied to each of the busbar pairs 220 a, 220 b from different power supplies 250 a, 250 b, thus providing different levels of electrical stimulation in the different voltage regions 280 a, 280 b of the thermal signature target form 210. These different levels of electrical stimulation in turn generate different levels of thermal stimulation, thus varying the IR radiation emitted from the different voltage regions 280 a, 280 b. These variations in emitted IR radiation can be utilized to create a realistic thermal signature to mimic a variety of desired military targets.
Another embodiment of the invention, shown in FIG. 4, contains a plurality of carbon-loading regions 380 a, 380 b in the target form 310. These plurality of carbon-loading regions 380 a, 380 b are created by adding differing amounts of carbon fiber to the conductive polymer material comprising the target form 310. These carbon-loading regions 380 a, 380 b have differing volume resistivity levels and therefore will emit different levels of IR radiation when electrically stimulated. Thus, the target form 310 can be manipulated to create a realistic thermal signature of the desired target.
There are multiple advantages of the thermal signature target form 10. First, the conductive polymer may be formed to any three-dimensional shape, including but not limited to, a human body shape or a military vehicle such as a tank, truck, or armored personnel carrier. These three-dimensional shapes therefore more accurately simulate real-world threats than traditional two-dimensional target panels.
Embodiments of the invention can also assist in training a user to more accurately identify a live target through visual recognition of a target's thermal signature. Users can utilize IR viewing equipment to see the target's 10 thermal signature at night or in low light levels. In addition, the target form 10 of the invention does not require that additional thermal elements be taped, stapled, or otherwise adhered to a target panel or form, thus reducing setup and maintenance time, which are highly desirable characteristics for military training. Furthermore, the continuously conductive polymer of the invention does not degrade as rapidly in performance when penetrated by multiple bullets during a live-fire training exercise, thus extending the target's useful life, reducing maintenance time, and decreasing overall cost of ownership.
For example, as can be seen in FIGS. 5-8, live-fire testing was performed on a prototype target form 610 of the invention. The target 610 was positioned next to a standard three-dimensional infantry target 710 and 500 rounds of 5.56 mm full metal jacket NATO ammunition were fired through both targets while the heated target 610 was powered to record the thermal signature performance.
FIG. 5 shows an infrared-spectrum thermal image of the heated target form 610 prior to live-fire testing and FIG. 6 shows the heated target form 610 immediately after live-fire testing. As can be seen, the heated target form 610 maintained excellent thermal image performance throughout the duration of the testing.
FIG. 8 shows a visual-spectrum optical image of the standard three-dimensional infantry target 710 following the live-fire testing and FIG. 7 shows a visual-spectrum optical image of the heated target form 610 following live-fire testing. As can be seen from the images, the heated target form 610 of the invention withstood the live-fire testing and exhibited similar self-healing properties to the standard three-dimensional infantry target 710.
The conductive thermoplastic material used to create the target form 10 of the invention eliminates any secondary operations of assembling a heating element to a pre-existing target panel or form because the target form 10 itself produces heat when stimulated by electrical energy. Elimination of these secondary operations will reduce overall cost of the product as well as reduce maintenance time of the customer due to the convenience of the single piece target design.
FIG. 9 illustrates a method of making the thermal target 10 described above in accordance with the invention. First, a thermoplastic pellet with a base polymer resin of High Density Polyethylene (HDPE) and a primary additive of carbon fiber at an approximate loading level of 50% is constructed, 801. The carbon fiber loading level is adjusted to control the volume resistivity of the compounded thermoplastic, 802. Additional carbon fiber will increase the volume resistivity of the thermoplastic while lower levels of carbon fiber will decrease the volume resistivity of the thermoplastic.
The conductive polymer pellets are extruded and cut into sheets which will be used in a secondary forming operation, 803. The sheets may have a surface treatment operation performed during the extrusion process to enhance the adhesion of any final finishing operations such as painting, screening or plating. The sheet may be thermoformed to any three-dimensional shape desired for the training exercises, 804. Slots, grooves or channels may be cut into the target form 10 to adjust current flow to areas of the target which require higher electrical power output. One or more busbar pairs 20 are connected to the target form 10 using a suitable mechanical fastening technique, 805. The busbars 20 are connected to a power source 50 to distribute the electrical current through the target body, 806. The finished target form 10 has a weatherproof connector 60 which interfaces with the power supply 50. The completed target form 10 may be painted or otherwise electrically insulated for safety considerations.
FIG. 10 illustrates a second example of the making of the thermal target 10 described above in accordance with the invention. First, a compounded thermoplastic pellet with a base polymer resin of High Density Polyethylene (HDPE) and a primary additive of carbon fiber at an approximate loading level of 50% is constructed, 901. The carbon fiber loading level is adjusted to control the volume resistivity of the compounded thermoplastic, 902. In this example, the conductive polymer pellets are rotationally molded to any three-dimensional shape desired for the training exercise, 903. Slots, grooves or channels may be cut into the target form 10 to adjust current flow to areas of the target which require higher electrical power output. One or more busbar pairs 20 to distribute the electrical current are connected to the target form 10 using mechanical fastening means, 904. The completed target form 10 may be painted or otherwise electrically insulated for safety considerations. The busbars 20 are connected to a power source 50 to distribute the electrical current through the target body, 905.
Accordingly, while the invention has been described with reference to the structures and processes disclosed, it is not confined to the details set forth, but is intended to cover such modifications or changes as may fall within the scope of the following claims.

Claims

1. A thermal target form comprising:

a formed target of a conductive polymer material;

a pair of busbars connected to said formed target;

a power supply; and

a connector interfacing between each busbar and said power supply.

2. A thermal target form of claim 1 wherein said formed target is three-dimensional.

3. A thermal target form of claim 1 wherein said conductive polymer material is loaded with approximately 50% carbon fiber.

4. A thermal target form of claim 1 wherein said formed target has slots, grooves, channels, or contours.

5. A thermal target form of claim 1 further comprising at least two pairs of busbars connected to said formed target.

6. A thermal target form of claim 5 wherein said pairs of busbars create a plurality of voltage regions in said formed target with differing voltage levels.

7. A thermal target form of claim 1 wherein said conductive polymer material is divided into a plurality of regions with different carbon fiber loading levels.

8. A thermal target form of claim 7 wherein each of said plurality of regions contains approximately 50% carbon fiber.

9. A thermal target form of claim 7 wherein said formed target has slots, grooves, channels, or contours.

10. A thermal target form of claim 7 further comprising at least two pairs of busbars connected to said formed target.

11. A thermal target form of claim 10 wherein said pairs of busbars create a plurality of voltage regions in said formed target with differing voltage levels.

12. A method of making a thermal target form comprising the steps of:

a) combining carbon fiber of an approximate loading level of approximately 50% to a base polymer resin of High Density Polyethylene to form a thermoplastic pellet;

b) adjusting the carbon fiber loading level to control the volume resistivity of said thermoplastic pellet such that the target form emits an IR signature that mimics the desired simulated target when an electrical source is added;

c) molding said thermoplastic pellet into a desired three-dimensional shape;

d) fastening a pair of busbars to the three-dimensional shape; and

e) connecting the busbars to a power source to distribute electrical current throughout the three-dimensional shape.

13. The method of claim 12 wherein said molding of said thermoplastic pellet into said three-dimensional shape further comprises the steps of:

a) extruding the thermoplastic pellet to form a sheet; and

b) thermoforming the sheet into said desired three-dimensional shape.

14. The method of claim 12 wherein said molding of said thermoplastic pellet into said three-dimensional shape is performed by rotational molding.

15. The method of claim 12 further comprising the step of:

forming slots, grooves, channels, or contours in the three-dimensional shape to adjust current flow to areas of the thermal target form which require higher or lower electrical power output.

16. The method of claim 12 wherein at least two pairs of busbars are fastened to the three-dimensional shape which are capable of creating a plurality of voltage regions in said three-dimensional shape.

17. The method of claim 12 wherein said adjusting of the carbon fiber loading level creates a plurality of regions with different carbon fiber loading levels.