U.S. patent number RE38,540 [Application Number 09/955,591] was granted by the patent office on 2004-06-29 for movable target system in which power is inductively transformed to a target carrier.
Invention is credited to Kyle E. Bateman.
United States Patent |
RE38,540 |
Bateman |
June 29, 2004 |
Movable target system in which power is inductively transformed to
a target carrier
Abstract
An improved track-mounted movable target system is disclosed.
Power is inductively transferred to a target carrier movable
between first and second locations. The transferred power is used
to power electrical equipment on board the target carrier. The
electrical equipment may include electric motors, lights,
solenoids, and control circuitry for the motors and solenoids.
Preferred embodiments of the invention are implemented as
track-based systems, as the track provides not only stability to
the target carrier, but also protection from stray bullets to the
conductive cable. For a first embodiment of the invention, power is
transferred to a target carrier via a stationary inductor and a
movable cable, which also provides motive force to the target
carrier. For a second embodiment of the invention, power is
transferred to a target carrier via a stationary cable and an
inductor movable with the target carrier. For this second
embodiment of the invention, electrical equipment on board the
target carrier includes a drive motor for moving the carrier
bidirectionally along the track. For both embodiments of the
invention, communications with the target carrier may be achieved
by modulating the frequency of the applied alternating current and
demodulating it at the target carrier to provide control signals
for control circuitry on board the target carrier.
Inventors: |
Bateman; Kyle E. (Provo,
UT) |
Family
ID: |
32510771 |
Appl.
No.: |
09/955,591 |
Filed: |
September 14, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
005436 |
Jan 10, 1998 |
05951016 |
Sep 14, 1999 |
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Current U.S.
Class: |
273/406 |
Current CPC
Class: |
F41J
9/02 (20130101) |
Current International
Class: |
F41J
9/02 (20060101); F41J 9/00 (20060101); F41J
007/00 () |
Field of
Search: |
;273/406,129S,121A,369,359,371,372 ;434/22
;336/115,116,117,118,119,129,130,131,132,136,73,75,77
;335/220,222,266,268,298 ;104/284,286,293,296,303,119 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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53-124813 |
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Oct 1978 |
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JP |
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659-426 |
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Apr 1979 |
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SU |
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1105-342 |
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Jul 1984 |
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SU |
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1318-461 |
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Jun 1987 |
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SU |
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1402-450 |
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Jun 1988 |
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SU |
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Primary Examiner: O'Neill; Michael
Attorney, Agent or Firm: Fox, III; Angus C.
Claims
What is claimed is:
1. A movable target system comprising: a target carrier movable
between first and second locations, said carrier having onboard
electrical equipment; a .[.stationary.]. power supply .[.having
first and second output connections.]. ; and a power transmission
system for transferring electrical power from the .[.stationary.].
power supply to the on board electrical equipment via at least two
mutually-coupled inductors, one of which is movable with respect to
another.
2. The movable target system of claim 1, wherein power is
transferable while one of said inductors is moving with respect to
another.
3. The movable target system of claim 2, wherein said pair of
inductors includes: a first inductor, which is an
electrically-conductive cable; and a second inductor comprising: a
coil having at least one turn of wire, said wire having first and
second ends which, respectively, form first and second leads; and a
ferromagnetic core which at least partially surrounds said cable
and which magnifies the inductance of said coil.
4. The movable target system of claim 2, wherein said core is
toroidally-shaped.
5. The movable target system of claim 2, wherein said core is
substantially in the shape of geometric solid enclosed by the
surface generated by rotating a rectangle 360 degrees about an axis
that is outside the rectangle, parallel to one side of the
rectangle, and equiplanar with the rectangle.
6. The movable target system of claim 3, which further comprises a
track on which said target carrier is movably mounted, said track
having a full-length channel within which said cable is positioned
along substantially the entire length of said track; first and
second power input connections on said target carrier to which said
electrical equipment is electrically coupled.Iadd.; .Iaddend.and
wherein said cable is movable, having first and second ends
respectively coupled to said first and second power input
connections, said first and second ends each also being secured to
said target carrier; and wherein said second inductor is
stationary, having first and second leads .[.respectively.].
coupled to said .[.first and second connections of said
stationary.]. power supply.
7. The movable target system of claim 6, which further comprises: a
first idler pulley longitudinally aligned with said channel and
positioned outboard of said first location; and a drive pulley
rotatably powered by a drive motor, said drive pulley aligned with
said channel and positioned outboard of said second location; and
wherein said cable is looped between said idler pulley and said
drive pulley.
8. The movable target system of claim 7, which further comprises a
second idler pulley mounted between said second location and said
drive pulley, said second idler pulley engaging said cable and
serving to maintain said cable within said channel, and wherein
said second inductor is positioned between said drive pulley and
said second idler pulley.
9. The movable target system of claim 8, wherein said electrical
equipment includes at least one electric motor for moving a target
and control circuitry for controlling the operation of said
electric motor.
10. The movable target system of claim 9, wherein said electrical
equipment further includes frequency sampling and decoding
circuitry, and wherein the frequency of an induced alternating
current in said cable matches that of an alternating current
applied to said second inductor by said .[.stationary.]. power
supply, and wherein the frequency of the applied alternating
current is modulated to provide decodable signals at the target
carrier which are sampled by said frequency sampling circuitry and
decoded by said decoding circuitry to produce control signals for
said control circuitry.
11. The movable target system of claim 10, wherein said electric
motor, said control circuitry, said sampling circuitry, and said
decoding circuitry are powered by direct current produced by
rectifying at least some of said induced alternating current.
12. The movable target system of claim 3, which further comprises:
an electrically-conductive track on which said target carrier is
movably mounted, said track having a full-length, upwardly-open
channel within which said cable is positioned along substantially
the entire length of said track; a first cable anchoring device to
which a first end of said cable is anchored, said first anchoring
device being longitudinally aligned with said channel, positioned
outboard of said first location, said first .Iadd.end of said
.Iaddend.cable .[.anchoring device.]. being coupled to .[.said
first power output connection via.]. said track; and a second cable
anchoring device to which the opposite, or second, end of said
cable is anchored, said second anchoring device being
longitudinally aligned with said channel and positioned outboard of
said second location; said second .Iadd.end of said .Iaddend.cable
.[.anchoring device.]. being electrically coupled to said second
power output connection; and wherein said second inductor is
affixed to said target carrier .Iadd.and said power supply has
first and second output connections, said first output connection
being coupled to said track, and said second output connection
being coupled to the second end of said cable.Iaddend..
13. The movable target system of claim 12, wherein said target
carrier includes means for lifting a portion of said cable from
said channel within the confines of said carrier as it moves along
said track.
14. The movable target system of claim 13, wherein said means for
lifting comprises: first and second guide pulleys rotatably and
rigidly affixed to said target carrier, said first and second guide
pulleys being positioned at least partially within said channel;
and at least one other guide pulley rotatably and rigidly affixed
to said carrier at a level above said first and second guide
pulleys, said cable being routed from said .Iadd.first
.Iaddend.cable anchoring device, beneath said first guide pulley,
out of said channel and over said at least one other guide pulley,
into said channel and under said second guide pulley, then to said
.[.first power output terminal.]. .Iadd.second cable anchoring
device.Iaddend., said cable passing through said .[.first
inductor.]. while .Iadd.said cable .Iaddend.is out of said
channel.
15. The movable target system of claim .[.14.]. .Iadd.12.Iaddend.,
where said electrical equipment includes a drive motor for driving
said target carrier along said track, at least one target movement
motor, and control circuitry for controlling the operation of said
drive motor and said at least one target movement motor.
16. The movable target system of claim 15, wherein said electrical
equipment further includes frequency sampling and decoding
circuitry, and wherein the frequency of the induced alternating
current in the second inductor matches that of .[.the.]. .Iadd.a
.Iaddend.source alternating current .Iadd.output by said power
supply.Iaddend., and wherein the frequency of the source
alternating current is modulated to provide decodable signals at
the target carrier which are sampled by said frequency sampling
circuitry and decoded by said decoding circuitry to produce control
signals for said control circuitry.
17. The movable target system of claim 16, wherein the source
alternating current is modulated to provide a stream of serial
binary data.
18. A movable target system comprising: a track having a channel
extending substantially the full length thereof; a target carrier
movably mounted on said track between first and second locations,
said carrier having first and second power-input connections and
onboard electrical equipment coupled to said first and second
power-input connections; a first idler pulley longitudinally
aligned with said channel and positioned outboard of said first
location; a drive pulley rotatably powered by a drive motor, said
drive pulley longitudinally aligned with said channel and
positioned outboard of said second location; a stationary power
supply having first and second power output connections; an
electrically-conductive drive cable having a first end that is both
electrically coupled to said first power-input connection and
secured to said carrier, said drive cable also having a second end
that is both electrically coupled to said second power-input
connection and secured to said carrier, said cable being looped
between said idler pulley and said drive pulley, said cable being
positioned within said channel between first and second locations;
and an input inductance device that is stationary with respect to
said track, said device having a coil with at least one turn of
wire, said wire having first and second ends respectively coupled
to first and second power output connections; and a ferromagnetic
core which at least partially surrounds said cable and which
magnifies the inductance of said coil.
19. The movable target system of claim 18, wherein said core is
toroidally-shaped.
20. The movable target system of claim 18, wherein said core is
substantially in the shape of geometric solid enclosed by the
surface generated by rotating a rectangle 360 degrees about an axis
that is outside the rectangle, parallel to one side of the
rectangle, and equiplanar with the rectangle.
21. The movable target system of claim 18, which further comprises
a second idler pulley mounted between said second location and said
drive pulley, said second idler pulley engaging said cable and
serving to maintain said cable within said channel.
22. The movable target system of claim 18, wherein said electrical
equipment includes control circuitry and at least one electric
motor for moving a target, said control circuitry controlling the
operation of said electric motor.
23. The movable target system of claim 22, wherein said electrical
equipment further includes frequency sampling and decoding
circuitry, and wherein the frequency of an induced alternating
current in said cable matches that of a source alternating current,
output by said power supply to first and second power output
connections, and wherein the frequency of the source alternating
current is modulated to provide decodable signals at the target
carrier which are sampled by said frequency sampling circuitry and
decoded by said decoding circuitry to produce control signals for
said control circuitry.
24. The movable target system of claim 23, wherein said electric
motor, said control circuitry, said sampling circuitry, and said
decoding circuitry are powered by direct current produced by
rectifying at least some of said induced alternating current.
25. A movable target system comprising: an electrically-conductive
track having an upwardly-open channel extending substantially the
full length thereof; a target carrier movably mounted on said track
between first and second locations, said carrier having first and
second input connections and onboard electrical equipment coupled
to said input connections; a stationary power supply having first
and second power output connections; an electrically-conductive
cable having first and second ends, said cable being positioned
within said channel between said first and second locations, except
within the confines of said target carrier; an output inductance
device mounted on and stationary with respect to said target
carrier, said device having a coil with at least one turn of wire,
said wire having first and second ends respectively coupled to
first and second power output connections; and a ferromagnetic core
which at least partially surrounds said cable, and which magnifies
the inductance of said coil, a first cable anchoring device to
which said first end of said cable is anchored, said first
anchoring device being longitudinally aligned with said channel,
positioned outboard of said first location, said first .Iadd.end of
said .Iaddend.cable .[.anchoring device.]. being coupled to said
first power output connection via said track; and a second cable
anchoring device to which said second end of said cable is
anchored, said second anchoring device being longitudinally aligned
with said channel and positioned outboard of said second location;
said second .Iadd.end of said .Iaddend.cable .[.anchoring device.].
being electrically coupled to said second power output
connection.
26. The movable target system of claim 25, wherein said core is
toroidally-shaped.
27. The movable target system of claim 25, wherein said core is
substantially in the shape of geometric solid enclosed by the
surface generated by rotating a rectangle 360 degrees about an axis
that is outside the rectangle, parallel to one side of the
rectangle, and equiplanar with the rectangle.
28. The movable target system of claim 25, wherein said first cable
anchoring device incorporates a cable tensioner.
29. The movable target system of claim 25, wherein said target
carrier includes means for lifting a portion of said cable from
said channel within the confines of said carrier as it moves along
said track.
30. The movable target system of claim 29, wherein said means for
lifting comprises: first and second guide pulleys rotatably and
rigidly affixed to said target carrier, said first and second guide
pulleys being positioned at least partially within said channel;
and at least one other guide pulley rotatably and rigidly affixed
to said carrier at a level above said first and second guide
pulleys, said cable being routed from said first cable anchoring
device, beneath said first guide pulley, out of said channel and
over said at least one other guide pulley, into said channel and
under said second guide pulley, then to said second cable anchoring
device, said cable passing through said .[.output inductance
device.]. .Iadd.ferromagnetic core .Iaddend.while said cable is out
of said channel.
31. The movable target system of claim 25, where said electrical
equipment includes a drive motor for driving said target carrier
along said track, at least one target movement motor, and control
circuitry for controlling the operation of said drive motor and
said at least one target movement motor.
32. The movable target system of claim 31, wherein said electrical
equipment further includes frequency sampling and decoding
circuitry, and wherein the frequency of an induced alternating
current in said output inductance device matches that of a source
alternating current output by said power supply to first and second
power output connections, and wherein the frequency of said source
alternating current is modulated to provide decodable signals at
the target carrier which are sampled by said frequency sampling
circuitry and decoded by said decoding circuitry to produce control
signals for said control circuitry.
33. The movable target system of claim 32, wherein said source
alternating current is modulated to provide a stream of serial
binary data.
34. The movable target system of claim 25, wherein at least a
portion of said induced alternating current is rectified to direct
current and used to power at least a portion of said electrical
equipment.
Description
FIELD OF THE INVENTION
This invention relates to equipment for target ranges and, more
specifically, to movable track-mounted target carriers having
onboard electrical equipment to which power must be supplied from
an external source. The invention also relates to induction-based
electrical power transmission systems.
DESCRIPTION OF RELATED ART
Movable target systems typically employ a target carrier that is
movable along a rail or track. There is often a requirement that
the target attached to the carrier be movable (e.g., pivotable
about its vertical central axis). The provision of linear movement
to the carrier and movement to the target with respect to the
carrier has resulted in various movable target system designs.
One solution to providing linear movement to a carrier and pivotal
movement to a target makes use of a pair of parallel conductor
strips mounted on the track which are electrically insulated from
one another and between which a voltage potential is applied.
Alternatively the track itself may serve as one of the conductors
(typically at ground potential) and a single conductor strip or
wire insulatedly mounted along the track serves as the other. In
either case, the carrier is equipped with brushes or rollers which
pick up electrical power from the conductors as the carrier moves
along the track, much as a toy electric train derives its power
from the rails. Such an arrangement is depicted in U.S. Pat. No.
3,128,096 to C. G. Hammond, et al. Power may be supplied to a first
electric motor which drives the carrier along the track, as well as
to a second electric motor which is used to pivot the target. Such
a design suffers from the drawback that bullet fragments and other
debris may alight on the conductor strips and thereby interfere
with the electrical connection between the brushes and the
conductor strip. Arcing between the brushes and the conductor
strips will result in the formation of oxides which will increase
the resistance at the connection and result in lower voltages being
supplied to the electric motors. In addition, the brushes tend to
wear with use, requiring periodic monitoring and replacement to
prevent harmful arcing conditions.
Another design employed to provide linear movement to a carrier and
pivotal movement to a target is depicted in U.S. Pat. No. 3,614,102
to J. Nikoden, Sr. A first insulated, single-conductor cable has
one end spooled clockwise on a rotatable take-up drum which moves
laterally about its central axis on a threaded shaft as the drum
rotates. The opposite end of the cable is connected to a target
carrier, providing motive force in one direction along a track and
one conductor for power at the carrier. A second insulated cable
has one end spooled counterclockwise on the rotatable take-up drum
and the opposite end connected to the target carrier, thus
providing motive force in a direction opposite that provided by the
first cable and a second conductor for power at the carrier. The
pitch of the threads on the shaft is equal to the diameter of the
first and second insulated cables. One of the cables wraps around
an idler pulley at the end of the track opposite the take-up spool
mechanism. Such a design is rather complex and requires constant
frequent lubrication of the threaded shaft and brush type contacts
to transfer current to each cable at the take-up spool.
Still another design used to provide linear movement to a carrier
and pivotal movement to a target utilizes a folded power cable
which is dragged behind the carrier. Such a target system design is
depicted in U.S. Pat. No. 4,889,346 to Donald M. Destry, et al.
Computer printers having a track-mounted, movable print head have a
similar cable connection arrangement. As the print head slides on
its track, a ribbon cable having conductors encased in a resilient
plastic sheath automatically folds upon itself and unfolds as the
print head moves. Electricity for both a linear motion motor and a
target pivoting motor are provided by the power cable which is
attached at one end to the carrier, and at the other end to a power
source. Abrasion to the insulated sheath covering the cable caused
by frequent movement of the cable, as well as fatigue and eventual
breakage of the cable conductors caused by frequent flexing of the
cable are significant problems of this design. Another problem
relates to the need to provide a mechanism which will maintain the
power cable (which is no lightweight ribbon cable) neatly folded as
the carrier moves toward the cable power source, regardless of the
carrier's position on the track.
What is needed is a simple and reliable new system for providing
linear movement to a track-mounted carrier and pivotal movement to
a target attached to the carrier which dispenses with contact
brushes, complicated cable spooling/despooling equipment, and
folded power cables.
SUMMARY OF THE INVENTION
The present invention is embodied in an improved movable target
system which meets the need heretofore expressed. Power is
inductively transferred to a target carrier movable between first
and second locations. The transferred power is used to power
electrical equipment on board the target carrier. The electrical
equipment may include electric motors, lights, solenoids, and
control circuitry for the motors and solenoids. Preferred
embodiments of the invention are implemented as track-based
systems, as the track provides not only stability to the target
carrier, but also protection from stray bullets to the conductive
cable.
For a first embodiment of the invention, power is transferred to a
target carrier via a stationary inductor and a movable cable, which
also provides motive force to the target carrier. An idler pulley
is mounted at one end of a track or rail, and a drive motor having
a drive pulley is mounted near the opposite end thereof A target
carrier, having an onboard power requirements, such as an electric
target-pivoting motor, is movably mounted on the track or rail. A
first end of an electrically-conductive drive cable is anchored to
the carrier, and also connected to a first power-input terminal on
the carrier. From the anchoring point on the carrier, the cable
extends directly to the drive pulley. The cable wraps around the
drive pulley, thus reversing directions. From the drive pulley, the
cable extends all the way to the idler pulley, wraps around the
idler pulley, and returns to the target carrier to which the second
end of the cable is also anchored. However, the second end of the
cable is connected to a second power-input terminal on the carrier,
which is electrically insulated from the first power-input
terminal. The drive cable, at some point along its length, passes
near a stationary inductor. For preferred embodiments of the
invention, the drive cable passes through the stationary inductor,
which is a closed-loop ferromagnetic core, such as a toroid, having
at least one turn of wire passing through the core's aperture. When
an alternating current is applied to the stationary inductor, an
alternating current of the same frequency is induced in the drive
cable. This induced current, received at the first and second
power-input terminals, is used to provide the target carrier's
onboard power requirements. Some of the induced current may be
rectified, filtered and regulated to provide DC power at the target
carrier. The frequency of the applied alternating current may be
modulated in order to send control signals to the target carrier.
Microprocessor-based circuitry on board the target carrier decodes
the modulated AC signals and converts them to binary signals which
may be used to directly control functions on board the target
carrier. Although not presently considered to be a preferred
implementation of the invention, at least this first embodiment of
the invention may be implemented as a trackless design by
maintaining the cable taut, and suspending the target carrier
directly from the cable.
For a second embodiment of the invention, power is transferred to a
target carrier via a stationary cable and an inductor movable with
the target carrier. One end of a conductive cable is connected to
one terminal of a stationary alternating current source that is
mounted near one end of an electrically-conductive track or rail
having a channel which extends the length of the track, and to
which the other terminal of the alternating current source is
connected. The cable is routed within the channel to the target
carrier, at which point it passes beneath a first in-channel guide
pulley that is rotatably mounted on the target carrier. The cable
then leaves the channel and passes over at least one out-of-channel
guide pulley that is rotatably mounted on the target carrier. While
the cable is outside the channel, it passes near or through an
inductor affixed to the target carrier. For preferred embodiments
of the invention, the drive cable passes through the inductor,
which is a closed-loop ferromagnetic core, such as a toroid, having
at least one turn of wire passing through the core's aperture. The
cable is then routed beneath a second in-channel guide pulley that
is rotatably mounted on the target carrier. From there, the cable
is routed to an anchoring device at the opposite end of the track,
which may incorporate a cable tensioning device. The cable
anchoring device is electrically connected to the track. As the
target carrier moves along the track, the guide pulleys mounted on
the target carrier lift a short section of the cable from the
track. When an alternating current is applied to the cable, an
alternating current is induced in the inductor affixed to the
carrier. The channel acts much like the outer conductor of a
coaxial cable, in that its electromagnetic shielding minimizes
power losses caused by energy radiated from the cable. For this
second embodiment of the invention, electrical equipment on board
the target carrier includes a drive motor for moving the carrier
bidirectionally along the track. Thus the current induced in the
inductor affixed to the target carrier is used to power not only
the drive motor, but any other electrical equipment that may be on
board the target carrier, such as motors which move the target with
respect to the carrier. Some of the induced current may be
rectified, filtered and regulated to provide DC power at the target
carrier. Communications with the target carrier may be achieved by
modulating the frequency of the applied alternating current. For a
preferred embodiment of the invention, modulation involves
alternating between two distinct frequencies so that a stream of
serial binary data may be sent to the target carrier.
Microprocessor-based circuitry on board the target carrier decodes
the modulated AC signals and converts them to binary signals which
may be used to directly control functions on board the target
carrier. For example, the decoded signals may direct the drive
motor to move the carrier forward or backward, or direct a
target-pivoting motor to rotate the target to a desired position.
Return communication for such information as hits on the target or
status information can be effected by modulating the load at the
coil at a frequency different from that of source alternating
current. This modulation will be reflected in measurable current
flow fluctuations at the alternating current source. These
fluctuations can be decoded in much the same manner that frequency
modulation is decoded by the circuitry on board the target
carrier.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational cutaway view of a first embodiment of
the improved movable target system;
FIG. 2 is a cross-sectional view of the first embodiment of the
improved movable target system of FIG. 1 through line 2--2;
FIG. 3 is a block schematic diagram of the electrical circuitry and
electrically-powered equipment employed in connection with the
first embodiment of the improved movable target system;
FIG. 4 is a side elevational cutaway view of a second embodiment of
the improved movable target system;
FIG. 5 is a cross-sectional view of the second embodiment of the
improved movable target system of FIG. 4 through line 5--5; and
FIG. 6 is a block schematic diagram of the electrical circuitry and
electrically-powered equipment employed in connection with the
second embodiment of the improved movable target system.
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the invention may be characterized as a
movable target system having a target carrier that is driven by a
movable, looped cable along a track. Electrical power is
transferred to the movable cable via a stationary inductor which is
inductively coupled to the cable. Power induced in the cable is
received by the carrier and used to power electrical equipment on
board the carrier. This first embodiment of the invention will now
be described.
Referring now to FIG. 1, an overhead track 101 of substantially
rectangular, U-shaped cross section, having an upward-facing groove
or channel (see FIG. 2, item 201) that extends along the length of
the track, is provided between two locations between which a target
must be movably positionable. A first idler pulley 102
incorporating a tensioning device 103, is mounted within the
channel 201 at a first end of the track 101. A drive pulley 104,
powered by a drive motor 105, is mounted in line with the channel
201 near the opposite, or second, end of the track 101. A second
idler pulley 106 is mounted at the second end of the track 101 so
that its grooved edge 107 extends into the channel 201. A target
carrier 108, having power input connections 109A and 109B and
anchoring brackets 110A and 110B, is movably mounted on the track
101 with grooved dielectric transport wheels 111A, 111B, 111C and
111D. The target carrier 108 is movable between first and second
locations. The maximum travel is dictated by several factors. The
absolute maximum travel will be the length of the track. This
maximum travel will be limited, first, by the location of the first
and second idler pulleys, which will obstruct movement of the
carrier is either of them are physically located within the
channel. The maximum travel may also be further limited by limit
stops which may be affixed to the track. In any case, the term
"inboard", as used in this disclosure refers to a direction toward
the center of the track 101, while the term "outboard" refers to a
direction away from the center of the track. Each of the grooved
wheels rides on one of the four corners of the track. Each grooved
wheel is affixed to the carrier by a bracket 112 (the bracket 112
is depicted for only grooved wheel 111B) which is riveted or
fastened with screws to a bulkhead 113, which is, in turn, retained
with screws 114 between opposing side plates 115A and 115B (not
shown) of the target carrier 108. Anchoring brackets 110A and 110B
are rigidly attached to side plate 115B. Electrical equipment,
which may include a geared target pivoting motor 116 and electrical
circuitry 117 for the controlling the target pivoting motor 116, is
mounted on board the target carrier 108. An insulated wire 118
connects power input connection 109B to electrical circuitry 117.
Power input connection 109A is attached directly to the target
carrier housing, which includes side plate 115A.
Still referring to FIG. 1, a first end of an insulated,
electrically-conductive cable 122 is secured to the first power
input connection 109A. From this first power input connection 109A,
the cable 122 extends to and is wrapped around the first anchoring
bracket 110A, from which the cable 122 is routed under and
partially around the second idler pulley 106, and looped around the
groove of drive pulley 105. From the bottom of the drive pulley
105, the cable 122 then extends to the bottom of the first idler
pulley 103, is looped around the groove of the first idler pulley
103 one-half turn, before returning to the target carrier 108. At
the target carrier 108, the cable 122 is wrapped around the second
anchoring bracket 110B, from which the cable 122 extends to the
second power input connection 109B. The opposite, or second, end of
the cable 122 is secured to the second power output connection
109B. An inductor device 119, characterized as having a coil with
at least one turn of wire, the wire having first and second ends
which, respectively, form first and second leads 120A and 120B, and
a ferromagnetic core which at least partially surrounds the cable
122 and which concentrates the magnetic flux of the coil thereby
increasing the coil's inductance. The ferromagnetic core may take a
variety of shapes. For example, the core may be toroidally shaped,
or substantially in the shape of a geometric solid enclosed by the
surface generated by rotating a rectangle 360 degrees about an axis
that is outside the rectangle, parallel to one side of the
rectangle, and equiplanar with the rectangle. The core of inductor
device 19 may also be a square shaped frame substantially in the
shape of a geometric solid enclosed between two perimetrally
parallel, equiplanar rectangles, one of which is smaller than and
inside the other, as they are simultaneously moved along a line
perpendicular to the plane in which they lie. The term
"substantially" is used to indicate that the square corners of the
surfaces so generated may be rounded. The leads 120A and 120B of
inductance device 119 are coupled to an alternating current power
source 121. In order to prevent stray bullets from piercing the
target carrier 108, it is protected on the side facing the marksman
with an angled, tempered steel plate 123. Likewise, the
target-pivoting motor 116 and the onboard control circuitry 117 are
protected with a vertically-oriented, tempered steel plate 124.
41
Still referring to FIG. 1, it should be readily apparent that as
the drive pulley 105 is rotated by the drive motor 106, the target
carrier 108 will move, in response to the movement of cable 122,
until it reaches the limit of its travel in one direction along the
track 101. Likewise, when the rotational direction of the drive
pulley 105 is reversed, the target carrier 108 will travel in the
opposite direction along the track 101 until it reaches the limit
of its travel at the opposite end of the track 101. Additionally,
when an alternating current is applied to the power input leads
120A and 120B of inductor device 119, a current is induced in
electrically-conductive cable 122. For the preferred embodiment of
the invention, alternating current of various frequencies within a
range of about 20 to 30 kilohertz and a potential of approximately
170 volts is applied to inductor device 119, which has 6 turns of
wire thereon. Thus, the current induced on the cable 122 is about
one-sixth of the applied voltage, or a nominal voltage of about 24
volts. As 24 volts is the maximum voltage that is still considered
low-voltage, no special shielding or ground-fault detection devices
are required as safety measures. Although the induced alternating
current could be utilized to directly power an AC target-pivoting
motor, for the preferred embodiment of the invention, nearly all
the induced AC current is rectified, filtered and regulated to
provide 5 volts DC, which is used to power all electrical equipment
on board the target carrier 108. Only a very small portion of the
induced AC current is used as is for sampling the frequency of the
AC power applied to inductor device 119. The particular frequency
applied to inductor device 119 is used as a control signal for
motor control on board the target carrier 108. This will be later
explained in more detail with reference to FIG. 3. Although it is
conceivable that a movable target system could be designed using an
uninsulated cable in place of the insulated cable 122, an
uninsulated cable must be adequately isolated from the track 101
and any other grounded items. The use of a steel cable having an
insulating sheath greatly simplifies design and construction of the
movable target system. The insulating sheath may be formed from a
material such as nylon, polytetrafluoroethylene, or other flexible
polymeric dielectric material. In any case, electrical contact to
an end of the cable 122 is made by stripping the insulated sheath
from the end thereof and securing the stripped end to the terminal
using one of many known techniques. A lug-type connector crimped to
the end of the cable and secured to power input connections 109A or
109B with a threaded nut is depicted.
Referring now to the cross-sectional view of FIG. 2, the
rectangular, U-shaped cross-section of track 101 is readily
visible, as is the channel 201 within the U-shaped cross section.
At certain locations along the track, the track 101 is suspended
from a threaded overhead support rod 202 that is anchored to a
bracket 203 that is slidable within the track 101. As the threaded
nut 204 is tightened on rod 202, both the bracket 203 and the rod
202 exert a force on the track, thus securing the support rod 202
to the track 101. A slidable plastic insert 205 provides separation
between the upper strand 122U and the lower strand 122L of drive
cable 122. The target carrier 108 rolls along the track 101 on two
pairs of perpendicularly angled, spaced-apart plastic guide wheels
which are rotatably affixed to the carrier 108, as heretofore
described. Though not evident from this cross-sectional drawing,
the first pair of guide wheels, 111A and 111B, are nearer the
viewer than the second pair of guide wheels, 111C and 111D. Each
wheel rides on one of the four edges, or corners, of the track 101.
Such a mounting arrangement provides a high degree of stability to
the target carrier 108 as it moves along the track 101. The
bulkhead 113, which is seen in FIG. 1 as an edge of a piece of
sheet metal and folded tabs by which it attached to side plate 115A
by threaded screws 114, is shown more clearly in this view. Both
the bulkhead 113 and the angled steel plate 123 have a cutout 206
to clear the track 101 and overhead support rod 202. In this view,
the target pivoting motor 116M and its geared-drive mechanism 116D
are more clearly seen. The geared-drive mechanism 116D is mounted
on a support plate 207 with screws 208. The support plate is
attached to the lower carrier housing 209 with screws 210. A
notched cam wheel 211 is affixed to the output shaft 212 of the
target-pivoting motor 116M/116D. Two of three micro switches 213A,
213B and 213C, which detect the location of the notches on the cam
wheel 211 are also visible. A target attachment fitting 214 is
rotatably positioned within an oil impregnated sintered brass
bushing 215, which is pressed into base plate 216, which secured to
lower carrier housing 209 with bolts 217. A hole 218 in the target
attachment fitting 214 is adapted to receive a cylindrical rod to
which the target is attached (neither the rod nor the target is
shown). The rod is retained within fitting 214 by securing bolt
219.
Referring now to the block schematic diagram of FIG. 3, the
circuitry 117 on board the target carrier 108 includes all circuit
items labeled 302-307. The alternating current power source 121 is
transformed by inductor device 119 (which functions as a primary
transformer winding) and the insulated drive cable 122 (which
functions as a secondary transformer winding), which together
constitute power transformer 301, into the induced alternating
current received at power input connections 109A and 109B. The
induced AC current is rectified by diode rectifier circuit 302,
filtered by filter circuit 302 and regulated by regulator circuit
304. The regulated DC current powers a microprocessor 305, which
samples the frequency of the induced AC power through signal
conditioning circuit 306. The microprocessor 305 decodes the
received AC frequency signal into position information for the
target-pivoting motor 116M. In response to both this decoded signal
and signals P1, P2 and P3 received from micro switches 213A, 213B,
and 213C, respectively, which make rubbing contact with the edge of
a notched cam wheel 211 affixed to the target-pivoting motor shaft
212, either a clockwise rotation signal or a counterclockwise
rotation signal is sent from the microprocessor 305 to a motor
driver circuit 307, which sends DC power to target-pivoting motor
116M in normal or reverse polarity until the desired target
position is achieved. It should be emphasized that all electrical
equipment on board the target carrier is powered by the regulated
DC current derived from the current induced in the drive cable
122.
A second embodiment of the invention may be characterized as a
movable target system having a target carrier movable along a track
which encloses a stationary cable to which alternating current is
applied. The carrier incorporates onboard electrical equipment that
at least includes an electric transport motor. The onboard
electrical equipment receives it power from an inductor which
slides along the stationary cable. This second embodiment of the
invention will now be described.
Referring now to FIG. 4, a conductive overhead track 401 of
substantially rectangular, U-shaped cross section, having an
upward-facing groove or channel (see FIG. 5, item 501) that extends
along the length of the track, is provided between two locations
between which a target must be movably positionable. A first cable
anchoring device 403A incorporating a cable tensioner 404 is
longitudinally aligned with and positioned at one end of the track
401, being electrically connected thereto. An alternating current
source 405, having first and second power output connections 406A
and 406B, respectively, is positioned at the opposite end of the
track. The first output connection 406A is electrically connected
to the track 401. A target carrier is 407 is movably mounted on the
track 401 in the same way that the target carrier 108 is movably
mounted to track 101 (see the description of FIG. 1). The target
carrier 407 is equipped with a cable lifting device consisting of
four idler pulleys 408A, 408B, 408C and 408D. An inductor device
409 is affixed to the target carrier between idler pulleys 408B and
408C. The physical characteristics of the inductor device 409 are
fundamentally the same as those identified for inductor device 119
of the first embodiment of the invention. A first lead 110A of
inductor device 409 is electrically connected to the target carrier
frame at input connection 411. The target carrier 407 is also
equipped with onboard electrical equipment which includes a drive
motor 412 having a resilient drive wheel 413 which rides against
the lower surface of the track 401, a target-pivoting motor 116M
having a geared drive 116D, and circuitry 414 for controlling the
operation of both motors. An insulated wire 415, which makes
electrical connection to the other, or second, lead 110B of
inductor device 409, is coupled to the circuitry 414. In order to
prevent stray bullets from piercing the target carrier 407, it is
protected on the side facing the marksman with a tempered steel
plate 416 that is positioned both vertically and angularly with
respect to the marksman. Likewise, the target-pivoting motor
116M/116D and the onboard control circuitry 414 are protected with
a vertically-oriented, tempered steel plate 121. A first end of an
insulated conductive cable 418 is conductively anchored to the
first cable anchoring device 403A, from which the cable 418 extends
to a second cable anchoring device 403B, which is longitudinally
aligned with the channel of track 401, stationary with respect the
track 401, and electrically connected to the second power output
connection 406B. Between the second cable anchoring device 403B and
the first cable anchoring device 403A, the cable is routed to the
target carrier 407, where it passes beneath idler pulley 408A, out
of the channel 401 and over idler pulley 408B, through the inductor
device 409, over idler pulley 408C, back into the channel 401 and
under idler pulley 408D. When a source alternating current is
applied to the conductive cable 413, a corresponding alternating
current is induced in the inductor device 409. Some of the induced
current may be rectified, filtered and regulated to provide DC
power at the target carrier. Communications with the target carrier
407 may be achieved by modulating the frequency of the applied
alternating current at AC source 405. For a preferred embodiment of
the invention, modulation involves alternating between two distinct
frequencies so that a stream of serial binary data may be sent to
the target carrier. Microprocessor-based circuitry 414 on board the
target carrier decodes the modulated AC signals and converts them
to binary signals which may be used to directly control functions
on board the target carrier. For example, the decoded signals may
direct the drive motor to move the carrier forward or backward, or
direct a target-pivoting motor to rotate the target to a desired
position. Nearly all the AC current induced in inductor device 409
is rectified, filtered and regulated to provide 5 volts DC, which
is used to power all electrical equipment on board the target
carrier 407. Only a tiny portion of the induced AC current is used
as is for sampling the frequency of the AC power applied to cable
418. A more detailed explanation of communications procedures will
be subsequently given with reference to FIG. 6.
Still referring to FIG. 4, it should be readily apparent that as
the target carrier 407 is moved in either direction along the track
401 by drive motor 412 between the limit of its travel as afforded
by the length of the track, the cable will be lifted out of the
channel by idler pulleys 408A, 408B, 408C and 408D within the
confines of the target carrier 407. In this way, the cable 418 is
protected from stray bullets. In addition, the channel 501 within
the track 401 acts much like the outer conductor of a coaxial
cable. Power losses caused by energy radiated from the cable 418
are minimized.
Referring now to the cross-sectional view of FIG. 5, the
rectangular, U-shaped cross-section of track 401 is readily
visible, as is the channel 501 within the U-shaped cross section.
In order to provide clearance for idler pulleys 408A, 408B, and
408C and 408D, track 401 is somewhat wider than track 101. Many
features visible within FIG. 5 are identical to those of FIG. 2.
This description will cover only the basic differences. The most
notable difference is the presence of the idler pulleys, which
extract the cable 418 from the channel 501 within the confines of
the target carrier 407. Only idler pulleys 408C and 408D are
visible in this view. Also notable is the presence of a single
strand of cable 418, as the cable is not looped within the channel
501. In addition, because of clearance requirements, there are no
plastic inserts such as item 205 of FIG. 2. Idler pulleys 408A,
408B, 408C and 408D may be secured to the target carrier 407 in
much the same manner as the grooved transport wheels 111A, 111B,
111C and 111D are attached. However, grooved transport wheel 111D
is replaced with a grooved drive wheel 502 that is mounted on the
output shaft of drive motor 412, which may be secured to the target
carrier frame with a mounting bracket (not shown). The drive motor
412 is also equipped with a pulse generator 503 and a sensor 504,
which will be described in more detail with reference to FIG. 6. In
this cross-sectional view, the end of inductor device 409 is seen.
The central aperture 505 of a closed-loop ferromagnetic core of
device 409 is readily visible in this view. For the sake of
simplicity, the windings on inductor device 409 are not shown in
this view.
Referring now to the block schematic diagram of FIG. 6, which is
similar to that of FIG. 3, the circuitry 414 on board the target
carrier 407 includes all circuit items labeled 602-608. The
alternating current power source 405 is transformed by the
insulated cable 418 (which functions as a primary transformer
winding) and the inductor device 409 (which functions as a
secondary transformer winding), which together constitute power
transformer 601, into the induced alternating current received at
terminal 411 and lead wire 415 (i.e., the outputs of inductor
device 409). The induced AC current is rectified by diode rectifier
circuit 602, filtered by filter circuit 603 and regulated by
regulator circuit 604. The regulated DC current powers a
microprocessor 605, which samples the frequency of the induced AC
power through signal conditioning circuit 606. For a preferred
embodiment of the invention, modulation involves alternating
between two distinct frequencies so that a stream of serial binary
data may be sent to the target carrier. The microprocessor 605
samples a pulsating DC signal at the received AC frequency from the
signal conditioning circuit 606, decoding this pulsating signal
into binary signals which, in turn, code for certain control
functions on board the target carrier. For example, one decoded
signal may direct the drive motor to move the carrier forward or
backward. In response to another signal decoded from the induced AC
and signals P1, P2 and P3 received from micro switches 213A, 213B
and 213C, respectively, either a clockwise rotation signal or a
counterclockwise rotation signal is sent from the microprocessor
605 to a motor driver circuit 607, which sends DC power to
target-pivoting motor 116M in normal or reverse polarity until the
desired target position is achieved. Motor driver circuit 608
controls drive motor 412. Drive motor 412 is responsible for
bidirectional movement of the target carrier 407 along the track
401. As with motor driver circuit 607, either a clockwise rotation
signal or a counterclockwise rotation signal is sent from
microprocessor 605 to motor driver circuit 608. Drive motor 412 has
a rotating pulse generator 503 attached to its output shaft 504.
The pulses are monitored by sensor 504, which feeds information
back to microprocessor 605 via signal line L1, so that the
microprocessor 605 can keep track of the target carrier's position
on the track 401. It should be mentioned that the drive motor of
the embodiment depicted in FIG. 1 may also be equipped with a pulse
generator and a sensor so that the position of the target carrier
108 may be monitored by a separate microprocessor offboard the
target carrier 108. Additionally, it should be emphasized that all
electrical equipment on board the target carrier is powered by the
regulated DC current derived from the current induced in the
inductor device 409. Nearly all the AC current induced in inductor
device 409 is rectified, filtered and regulated to provide 5 volts
DC, which is used to power all electrical equipment on board the
target carrier 407. Only a tiny portion of the induced AC current
is used as is for sampling the frequency of the AC power applied to
cable 418.
Although only a single embodiment of the improved movable target
system is depicted and described herein, it will be obvious to
those having ordinary skill in the art that changes and
modifications may be made thereto without departing from the scope
and the spirit of the invention as hereinafter claimed. For
example, although the preferred embodiments of the improved movable
target system as heretofore described have been implemented as a
target carrier movable along an overhead track, the system
principles may be readily adapted to a system having a target
carrier movable along a ground-supported track, or even as a
trackless system, with the target carrier suspended on the
conductive cable.
* * * * *