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TECHNICAL FIELD
The present application relates to methods and apparatus for determining positional information and a computer-implemented approach for detecting and retrieving positional information from targets using impact detection.
BACKGROUND OF THE INVENTION
Targets are used in training for military and civilian marksmen to improve the accuracy and in particular to promote a correct location of impact on such targets. Current target systems utilize knock sensors attached to High Density Polyethylene plastic targets to determine if a target has been hit. If a projectile (e.g., a bullet) hits anywhere on the plastic including non-kill areas, it will drop. The lack of differentiation among different areas of such targets produces negative training by giving a shooter the impression that his shots are lethal when they are not. In particular, an impact on only a portion of such a target would produce a lethal blow while impact on other portions of the target would be non-lethal.
It is thus desirable to produce targets that determine a location of impact for both penetrating and non-penetrating rounds and which provide such information to a user. “Kill” and “non-kill” zones may be established on such targets to determine the lethality of impact of a projectile or penetration therein. By creating these zones and/or locating the location of impact the target or target display system could respond accordingly thereby producing a more realistic response.
SUMMARY OF THE INVENTION
This invention shows how to use resistive/piezoelectric materials in order to detect target impact or penetration.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view showing a resistive matrix with 2 conductive busses representing a kill zone in one embodiment.
FIG. 2 is an elevational view showing a larger resistive matrix with 2 conductive busses representing a non-kill zone in one embodiment.
FIG. 3 is a perspective view showing a layering order for combining the kill zone sensor of FIG. 1 and the non-kill zone sensor of FIG. 2 with an insulating dielectric layer into a kill/non-kill target in one embodiment.
FIG. 4 is an elevational view showing layers used to create a bullseye target in one embodiment.
FIG. 5 is a schematic of a sensing system that utilizes a programmable resistor to automatically balance a wheatstone bridge in one embodiment.
FIG. 6 is a flowchart showing an algorithm for zeroing the wheatstone bridge of FIG. 5 when a new target is requested in one embodiment.
FIG. 7 is a perspective view of a mannequin head and torso having a kill zone in the center and a non-kill zone wrapped around the kill zone in one embodiment.
FIG. 8 is a perspective view depicting a piezoelectric membrane with both sides thereof coated with a conductive membrane in one embodiment.
FIG. 9 is a schematic of a sensing circuit for a capacitive membrane sensor in one embodiment.
FIG. 10 is an elevational view of a carbon fiber and inert strand weave used to create a penetration detection sensor in one embodiment.
FIG. 11 is a diagram of a contact sensitive membrane formed from conductive ink and dielectric ink in one embodiment.
FIG. 12 is a schematic of a sensing circuit for the contact sensitive membrane of FIG. 4 in one embodiment.
FIG. 13 is a perspective view of a programmable thermal target with hit sensing capability in one embodiment.
FIG. 14 is a schematic of a programmable thermal target with hit sensing capability in one embodiment.
FIG. 15 is a perspective view of a programmable thermal target with hit sensing capability in one embodiment.
FIG. 16 is a perspective view of a programmable thermal target with hit sensing capability in one embodiment.
DETAILED DESCRIPTION OF THE DRAWINGS
Systems and methods for determining an impact of a target with a projectile are provided herein. In one embodiment, a plurality of conductors form a resistive matrix formed of horizontal and vertical conductors as depicted in FIG. 1 with opposite parallel buss bars connected to opposite sides of the matrix. A target 101 includes a graphic colloidal suspension coating or resistive/conductive ink which may be bonded to a thin sheet of plastic to form a contiguous resistive matrix or grid 101. Two busses of conductive ink and/or conductive foil 102 connected to grid 101 are used to sense a resistive change that occurs when grid 101 is penetrated by a projectile. A potential difference is placed across the busses causing current to flow across the resistive grid from one buss to the other. A direct current (DC) or alternating current (AC) would be placed across the busses to supply power to grid 101.
As indicated, a projectile (e.g., a bullet) may penetrate target 100 when such target is used for training or other purposes and such projectile may penetrate the plastic sheet and resistive traces of grid 101 forming target 100. The removal (i.e., by a projectile) of the resistive traces, or other conductor used to form grid 101, causes an overall change in the resistance of grid 101, i.e., the entire circuit of target 100. A simple resistive sensing circuit may be used to detect the change in resistance and generate a signal indicating that a zone (e.g., grid 101) was hit. An indication (e.g., a text message, graphic, light, etc.) of such a hit may be provided to a user (e.g., by a computing unit to a display screen). FIG. 2 depicts a second target 200 which is larger than target 100 and includes busses 202 similar to busses 102 for target 100. A grid 201 of horizontal and vertical conductors may connect such busses. Grid 201 may be formed of conductive ink and/or conductive foil as described relative to grid 101. It will be understood by one skilled in the art that such conductors could be connected to such busses in alignments other than such a horizontal and vertical pattern and further that such busses could be connected in a non-grid pattern. For example, a plurality of horizontal conductors could connect such busses or the busses could be connected by a plurality of angled non-perpendicular conductors relative to such busses.
Target 200 in FIG. 2 is significantly larger than target 100 in FIG. 1 thus allowing the ability for a smaller target to be superimposed on a larger target to generate a multi zone target. FIG. 3 depicts one embodiment of such a multi-zone target 300 by placing a dielectric insulator 302 between target 100 shown in FIG. 1 and target 200 shown in FIG. 2. In this embodiment a kill zone could be designated as grid 101 formed from FIG. 1 and a non-kill zone could be formed from grid 201 of FIG. 2. In the embodiment of FIG. 3, a projectile penetrating the kill zone (i.e., grid 101) would also penetrate the non-kill zone (i.e., grid 201) and both signals would be interpreted as a kill shot. However, if a projectile penetrated only the non-kill zone grid (i.e., grid 201, but not grid 101) only a non-kill zone signal would be generated. The dielectric insulator would only be necessary if it was desired to silk screen both circuits on one single sheet of thin plastic. If individual sheets of plastic for each circuit were used then the plastic would act as the insulator between zones and such a dielectric insulator would not be utilized. In another example, a first target and a second target could form a multi-zone target utilizing different technologies. For example, a first target (e.g., target 100) could be a resistive matrix coupled to a resistive sensing circuit, as described above, while a second target could include piezoelectric material, as described below, or could include an accelerometer. In such a case the first target could be used as a kill zone while the second target (on which the first may be superimposed) may be a non-kill zone indicating the target is hit but that a shot is not lethal, similar to target 300 described above.
FIG. 4 depicts a bullseye target 400 in another embodiment of the invention. An inner conductive buss 401 may be formed from conductive foil or conductive inks such as nickel, copper or silver. Resistive segments 405 extending radially and formed as lines rotated (polar) 360 degrees with concentric circles create a sensor. The resistive segments could also be formed of conductive foil or inks as described above, for example. A dielectric layer 402 may be used to protect the inner ring sense trace (i.e., inner buss 401) from touching, and electrically connecting to, resistive segments 405 or an outer ring buss 403. Each of these layers is applied to a thin sheet of plastic 404 in the following order: inner conductive ring 401, dielectric layer 402, outer conductive ring 403, resistive segments 405 and lastly a graphical image (not shown). As described above, an impact which removes a portion of resistive segments 405 would create an increased resistance which would be detected by a resistive sensing circuit as described above. An impact which penetrates such resistive segments would thus indicate a “hit” or a “kill”.
FIG. 5 shows an embodiment of a sensing circuit 500 that contains a wheatstone bridge formed from four resistors R1501, R2502, R3507 and R4508 which may be utilized in conjunction with the targets depicted in FIGS. 1-4. R1501 is a programmable variable resistor and R2502 represents a resistive penetration sensor (e.g., grid 101, grid 201) shown in FIG. 1 and/or FIG. 2. The voltage across the wheatstone bridge is sensed by 2 opamps 503 and 504. An output 505 of the 2 opamp circuit will generate a voltage difference across the wheatstone bridge. This output may be digitized using an A/D converter and processed to determine if a resistive sensing membrane has been penetrated. When the resistive sensing membrane is penetrated there will be an increase in resistance of R2502 causing the wheatstone bridge to become unbalanced generating a voltage increase at the output 505, thus indicating that a target (e.g., target 100, target 200) has been penetrated. Every time the target is raised (i.e., prepared to be used) R1501 will be adjusted to zero out the wheatstone bridge. A multitude of independent zones could be created sharing a common power buss allowing each zone to generate its own unique signal in another embodiment.
FIG. 6 shows a flow chart of an embodiment of an algorithm that allows for the wheatstone bridge to be zeroed prior to engagement (i.e., use of a target). When a new target 601 is requested (e.g., by a user pressing a button on a display screen or otherwise indicating that a new target should be displayed or that a previously used target be redisplayed), R1 of FIG. 5 is adjusted until the wheatstone bridge is balanced/zeroed out at step 602. This insures that a minimal voltage difference will appear to the opamp circuit. After the bridge is zeroed out the acquisition system starts sampling the kill and non-kill zones of a target (e.g., target 300) for voltage increases at step 603. The target is then raised into view for a shooter to engage at step 604. If a voltage difference increase is detected by a kill zone acquisition system (e.g., a computing unit running a program of instructions to carry out the steps of FIG. 6) at step 605, a kill shot is scored at step 606, the target is lowered at step 607 and the acquisition system stops attempting to acquire at step 608. If the non-kill zone acquisition senses a voltage difference increase at step 609 then a non-kill shot is scored at step 610 and the system returns to monitor both the kill and non-kill zones for voltage difference increases. One skilled in art of electronics and software development could produce a multitude of different techniques for achieving this invention and not deviate from the core essence or spirit of this invention.
The example described above could be applied to more than just two dimensional surfaces. FIG. 7 shows a three dimensional mannequin torso target 700 and head wrapped with a resistive matrix 702. The matrix could be created not only using resistive ink, conductive ink, and dielectric coatings, but could also be created using resistive fiber such as a carbon fiber shown in FIG. 9 so that the molded contours are held together with the same fiber that senses a penetration. In the embodiment depicted in FIG. 7, 3D target 700 has a resistive matrix kill zone 703 located inside a center of the torso with sensing busses 704 protruding out of a bottom thereof. As depicted in FIG. 7, matrix kill zone 703 may be formed as a cylinder inside torso shaped matrix 702. The outer wrap formed as matrix 702 has sense wires 701 that also protrude out of the bottom of target 700 for sensing non-kill zone penetration. When a projectile penetrates the kill zone (i.e., grid matrix 703) it will also penetrate the non-kill zone membrane/sensor (i.e., grid matrix 702), and since both signals would be generated this would be interpreted as a kill shot and displayed to a user on a display, for example. If only the non-kill zone membrane/sensor grid (i.e., matrix 702) was penetrated, then a non-kill shot would be interpreted and indicated on a display to a user, for example.
In another example, a piezoelectric film could be used to detect both an impact and/or penetration of a target. FIG. 8 depicts a metalized piezoelectric film 801 typically including Polyvinylidene Fluoride (PVDF) 803 coated on both sides with nickel, silver or other conductive metals as shown on a tab 802 and a tab 804. When placed onto a sheet of plastic such as High Density Polyethylene (HDPE) to provide support, a non-lethal weapon such as a paint ball, pellet/bb guns, or mil sims could be used to generate a signal indicating a zone (e.g., a target or portion thereof) has been hit. Live ammunition (e.g., bullets) would also generate a signal, but multiple penetrations of the film by the projectiles would eventually deteriorate the sensor formed by film 801. For example, when a disturbance (e.g., an impact) occurs on film 801 a voltage is generated by the piezoelectric film and creates a potential difference between tabs 802 and 804. This voltage signal would be used to indicate that the zone (e.g., film 801) was hit. Because the cost of piezoelectric film is prohibitive for large targets, another embodiment could simply use piezoelectric sensors bonded to a sheet of plastic/wood/metal spanning a desired zone of a larger target and such a sensor would generate a signal when that zone of the larger target was impacted by a projectile.
In another embodiment, a capacitive target sensor (not shown) could utilize a metalized sheet of plastic to form a capacitor similar to the construction shown in FIG. 8. Such a sheet of plastic could be coated on both sides with nickel, silver, or other conductive metal or metal film. When such a sensor is penetrated (e.g., by a projectile) it would change the capacitance of the membrane that could be attached to a circuit also shown in FIG. 9. A variable capacitor 901 simulates a change in capacitance of the capacitive sensor. An opamp 902 is configured so that it will oscillate approximately to the frequency of ½*R1*C1. The detection of a projectile hitting the sensor is possible by taking an output 903 and feeding it into a frequency counter. One skilled in art of electronics could produce a multitude of different techniques for achieving this invention and not deviate from the core essence or spirit of this invention.
In another embodiment, carbon fiber could be used to sense target penetration. For example, carbon fiber or carbon nano tubes could be formed into a thread and weaved into a repeating pattern with inert fibers as shown in FIG. 10 to create a target penetration sensor 1000. In this embodiment, the carbon fiber/carbon nano-tube threads 1001 are placed between 2 inert horizontal threads 1004 that are electrically insulating. The same pattern is used vertically with conductive fiber 1002 placed between 2 inert threads 1003. An electrical potential is applied across busses 1005 connected to the conductive fibers by a sensing circuit. When a projectile penetrates the grid formed by the conductive threads the resistance changes causing the sensing circuit to generate a signal indicating that the zone has been hit. In another example, inert threads would not be utilized between the carbon fiber threads, and instead carbon fibers having a very low resistance would be used by themselves (i.e., without the inert threads). Entire two dimensional and three dimensional targets could be formed of this material (i.e., sensor 1000). One skilled in art of fiberglass manufacturing and weaving could produce a multitude of different techniques for achieving this invention and not deviate from the core essence or spirit of this invention.
In another embodiment, conductive ink and dielectric ink may be used to create a pressure sensitive target. FIG. 11 shows a target sensor 1100 comprised of 2 sheets of plastic. A top sheet 1104 has only horizontal lines (Rows) 1101 of conductive ink facing down. A bottom plastic sheet 1105 includes conductive ink traces 1103 and dielectric insulating traces 1102 forming adjacent alternating vertical lines (Columns) facing up. The dielectric traces are slightly higher (i.e., taller or thicker) than the conductive traces preventing the top horizontal traces from coming in contact with the bottom vertical conductive traces. An electric potential is placed across the top conductive traces and the bottom conductive traces. When sensor 1100 is disturbed (e.g., hit) by a non lethal projectile, such as a paint ball, pellet/bb guns, or mil sims, it would cause the semi-pliable dielectric trace to compress allowing the top conductive trace to come in contact with the bottom conductive trace causing current to flow between the effected columns and rows. A simple circuit could be used to detect the exact intersection of rows and columns (i.e., the point of impact) and display that information remotely. A target response controller could be programmed to react differently (e.g., indicate a “kill” or “non-kill” zone on a display) depending on where the sensor was hit as described above. One skilled in art of silk screening manufacturing and electronics could produce a multitude of different techniques for achieving this invention and not deviate from the core essence or spirit of this invention.
A sensing circuit 1200 usable with sensor 1100 of FIG. 11 is depicted in FIG. 12 in one embodiment. The circuit needed to drive sensing circuits 1201 and 1204 may be created by biasing the columns to +v reference voltage through a sense resistor 1202 and rows to a ground or negative potential through a sense resistor 1203. When the membrane is at rest the sense resistors do not draw any current and the voltage entering the sense circuit remains at its reference voltage. When an impact occurs, e.g., at a point 1205, both the column and the row conductive membrane 1101 and 1103 (FIG. 11) come in contact with each other causing the sense resistors 1202 and 1203 to draw current thereby causing the respective voltage entering the respective sensing circuit to change. The sensing circuit converts that data to row/column information (i.e., at the location of impact) and sends it to a remote/local client for processing. Thus, the location of impact (e.g., point 1205) may thus be determined in output to a display screen or otherwise. Further, a “hit”, “miss”, “kill”, or “non-kill” may also be output to such a display.
In another example, a thermal target with penetration sensing capability may be created using conductive/resistive ink as shown in FIG. 1 or conductive and or resistive fiber as shown in FIG. 7 by applying enough current through conductive busses 101 and/or 701 respectively to cause the resistive ink/fiber to heat up to create a desired thermal signature(s). By monitoring the current entering a target with a current sensor one could detect a penetration (e.g., by a projectile) of the sensor when the current fluctuates. Such a thermal target may be useful as described in co-owned U.S. application Ser. No. 11/853,574 incorporated herein by reference, wherein a thermal signature of a desired target (i.e., “foe”) and a target (i.e., “friend”) to be avoided may be different. For example, one may train to avoid shooting at a non-combatant while training to shoot at a correct portion of (i.e., a “kill” zone) of a “foe”.
In a further example, FIG. 13 depicts a target 1300 segmented into individual zones and each zone powered with a corresponding current sensor such that a multitude of configurations are possible as further shown in a circuit 1400 depicted in FIG. 14. Each row 1301 and/or multiple rows are supplied with a positive voltage and selected by a FET Row Driver Selector 1402. Each column 1303 is supplied with a negative voltage and/or a ground and is selected by the FET Column Driver Selector 1403. A current sensor 1302 and a corresponding heating element 1401 may include a resistive ceramic plate, resistive ink, resistive foil, or heat/cooling pumps such as Peltier chip or ionic wind engines. By pulse width modulating the FETs a thermal signature (e.g., a representation of a threat or friend) can be presented to a shooter, for example. The thermal signature produced would be programmable and would be selectively changeable. In one example, a resistive ink on a plastic embodiment could have thermal absorption material on a back side thereof to hold heat and act as a thermal collector. This would allow for thermal stability and prevent a segment of a target (e.g., target 1300) from going cold while not active. One would be able to detect which segment (e.g., at sensor 1302) of such a target (e.g., target 1300) was hit (e.g., by a projectile) when a current to a particular segment changes due to a resistance change of the membrane.
In another embodiment, a thermal generator 1500 can be created using programmable cells in which each cell has its own register that holds a percentage of modulation needed to drive that cell or a segment as depicted in FIG. 15. Such segments may be powered by row and column power busses 1501, 1503 as shown in FIG. 15 with each cell/segment containing its own Pulse Width Modulation (PWM) register. Each register is serially addressable with a unique address such as hex(0000) being row 0, column 0 and address hex(FFFF) being row 255, column 255 respectively. Each register control system is capacitively coupled to allow control commands that are isolated from the power supplied on the same lines using X10, LonWorks, EIB/KNX, BACnet or similar protocol. For example, if a 16 bit register is loaded with a hex (0000) then the segment PWM is 0% and therefore not powered. If the register is loaded with a hex(FFFF) then the cell/segment is pulse width modulated (PWM) at 100%. The address and PWM word is sent out over the power buss to all cells/segments, but only a cell having an address that matches that of the command sent will load the PWM word into its register. Thus, the use of such pulse width modulation relative to individual addresses of individual cells of a target may allow portions of such a target (i.e., at the location of individual cells) to be individually controlled to produce a desired thermal signature or multiple thermal signatures on the target based on the addressability and use of pulse width modulation.
In another unillustrated embodiment a thermal generator/cooler could be instrumentated with piezoelectric sensors as shown in FIG. 8 or pressure sensors as show in FIG. 11 to create a target. Non-lethal rounds such as paintball rounds can be used to impact such a target without destroying the thermal generator/cooler. One skilled in art of silk screening/ceramics manufacturing and electronics could produce a multitude of different techniques for achieving this invention and not deviate from the core essence or spirit of this invention. One skilled in art of electronics could produce a multitude of different techniques for achieving this invention and not deviate from the core essence or spirit of this invention.
In another embodiment, a thermal generator, as described relative to FIG. 13 and FIG. 15, may be constructed using electromagnetic induction to heat metal panels for use in a target. FIG. 16 shows an example of such a programmable thermal generator system 1602. In particular, metal blocks 1602 may be separated by a non-thermal conductor such as foam, plastic, or ceramics. Each block as a metal post 1601 either screwed into it or welded on to it. Metal post 1601 has a coil 1603 of heavy gauge wire wrapped around it and is modulated at high voltage using FET row 1604 and column 1605 drivers. As described above relative to target 1300 in FIG. 13 and target 1500 in FIG. 15, system 1600 may be pulse width modulated (e.g., by a controller coupled to drivers 1604, 1605) to cause eddy currents to form in each post (e.g., post 1601) generating heat that will propagate into the metal block in response to and represent a heated panel. The blocks described may be utilized to generate a thermal signature (e.g., a friend or foe image) on any object which could receive such metal blocks, such as tank, automobile, or other large object which may be utilized for target practice by a marksman. In another example, such blocks may also be formed as a continuous monolithic panel (i.e., absent the non-thermal conductor s) of such a large object with such a panel having multiple posts as described above. Different portions of such a panel could be selectively controllable relative to other portions of the panel to provide different thermal signatures relative to each other. Further, the systems described could also be instrumentated with piezoelectric sensors to detect projectile penetration or impact as described above.
Another method for detecting impact on a target would be to place the blocks (e.g., blocks 1602) described above into a housing that would allow them to move against a spring. Such a spring could be placed behind the post and have a diameter smaller than the post forcing the plate forward against a retaining fixture. The coil could be fixed onto the base supporting the spring and allow the post to move freely through it. This would cause a significant change in current draw in response to the metal block being impacted and forcing the spring to compress moving more of the post into the coil causing a larger current draw than when the block is at rest. By monitoring the current for each segment and storing a rest state current for comparison one would be able to detect which block was impacted by seeing an increase in current draw. If the example shown in FIG. 16 were not to have any spacing and in fact it was one contiguous sheet with a multitude of posts attached to it, as described above, then electromagnetic induction could be used to heat up specific sections of the large sheet by applying controlled current to each section to achieve desired temperatures. One skilled in art of electronics could produce a multitude of different techniques for achieving this invention and not deviate from the core essence or spirit of this invention.
As described above, various training targets in accordance with the present invention may allow a determination of a location of impact or penetration of a projectile or a general location of an area of a target of such an impact or penetration. Such targets may further be augmented with a thermal generation system to allow a thermal signature to be presented on a target to mimic a signature of a “friend” or “foe” to aid training of a marksman. The various systems for detecting an impact or penetration may be combined with the various systems of thermal generation to arrive at various different targets using these systems. The various targets, sensors, and/or sensing circuits described above may be coupled to a computing unit and/or a display to allow a user to receive information that a target has been hit. Such display could indicate merely a hit or a particular location of such a hit provided via a text message, graphic, light or other such indication.
Also, the various technologies (e.g., resistive, pressure sensitive, capacitive, acceleration based) described above for the various targets, target sensors, and films could be used in a single target system having multiple target zones coupled to a controller for controlling the various targets and determining and indicating hits on such targets. For example, a first target zone could be a resistive target while a second target could be pressure sensitive, capacitive, or acceleration based. Target zones utilizing such different technologies could be superimposed on each other or placed alongside each other to produce kill or non-kill zones as desired according to a particular training situation. Each such zone could also be controlled to generate different or identical thermal signatures.
Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.
Patent Application
20110248448
