Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROU~D OF~ THE INVENTION
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1. FIELD OF THE INVENTION
The present invention relates to a firing range and
more particularly the present invention relates to a firing
range for use in training of personnel in marksmanship.
2. THE PRIOR ART
At the present time, when personnel are trained in
firing a weapon such as a rifle it is common to utilize a
static firing range in which the personnel fire their weapons
at targets which are remote from the firing point, the posi-
tion that each round impinges on the target being indicated by
further personnel acting as markers who are located adjacent
the targets but protected by an earth bank or the like.
This arrangement suffers from the disadvantage that
for every trainee marksman there must be a person to act as a
marker, and furthermore a rigid target must be utilized which
must be repaired after each shooting session so that the point
of impact of further rounds on the target can readily be de- `
termined.
A further disadvantage of this prior arrangement is
that the sport of shooting is not appealing as a spectator
sport since spectators cannot readily see how the shooting is
progressing.
Yet a further disadvantage of the prior proposed
arrangement is that personnel training the trainee marksman
find it difficult to monitor the progress of a large number of
trainee marksmen and have to inspect the targets by means of a
telescope or binoculars in order to assess how a trainee marks-
man is performing. This procedure is time-consuming and in- `
convenient.
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Various at~empts have been made to overcome these
disadvantages.
Several proposals have been made in which transducers
or similar shock wave detec~ors are connected directly to a ri-
gid target or a rigid member located behind the target, thedetectors being adapted to detect shock waves or vibrations
generated in the target o~ member by the impact of a bullet on
the target. The signals from the detectors are fed to a cal-
culating device which calculates the position o~ the bullet or
other projectile, and which causes that position to be dis~
played or stored. Specifications that disclose the systems o~
this general type are U.S. Patent Specification 2,973,964
(Zito) and U.S. Patent Specification 3,~78,495 (Gilbert).
Both these particular systems suffer from the disadvantage
that a rigid target or member must be used, and the rigid tar-
get or member must be replaced after a certain period of use,
since otherwise the target or member will be perforated by
bullets fired at the target and then the target or member will
not satisfactorily transmit the shock waves or vibrations
generated when a bullet impinges on the target. Also, if a
rigid target is used, with very accurate marksmen a hole will
soon be generated in the region of the "bull" of the target,
this hole having a diameter greater than the diameter of the
bullets being fired at the target. Thus after a period of
time a bullet may pass through this hole without generating
shock waves, and a shot that should be recorded as a "bull"
will be recorded as a "miss". Furthermore since the trans-
ducers are spaced around the periphery of the target or member
the transducers may thèmselves be hit by bullets fired at the
target, and thus the transducers may be damaged. Thus these
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systems suffer from the disadvantage of expense in that both
the targets or rigid membe~s and the transducers will have to
be replaced at frequent intervals.
Various alternative proposals have been made in which
transducers or the like are utilized to detect an air-carried
shock wave generated by a bullet or projectile which travels
at a speed faster than the speed of sound in air. Such a pro-
jectile can be called a supersonic projectile. One very simple
proposal of this type is disclosed in U.S. Specification
2,783,047 (Faxen) in which a single shock wave sensitive device
is operated to generate a signal in response to a shock wave
generated by a supersonic projectile such as bullet and impin-
ging on the device. The shock wave sensitive device is moun-
ted in a target area zone bounded by a wall so that the device
will be responsive to shock wave impulses produced by bullets
entering the target area but not those produced by projectiles
which pass outside the target area. It will be appreciated,
therefore, that this particular arrangement will only be able
to distinguish between a "hit" and a "miss" and will not be
able to provide any accurate information concerning the pre-
cise position at which a bullet impinged upon the target area.
A further proposal in which airborne acoustic shock waves pro-
duced by a supersonic projectile such as a bullet are utilized
is described in U.S. Patent Specification 3,77~,059 (Rohrbaugh)
and in this specification two metal rods are located respec-
tively adjacent the base and one side edge of the target, there
being acoustic transducers attached to the ends o~ the rods.
When a bullet is fired at the target the shock wave generated
by the bullet will impinge on the rods, and a resultant acous~
tic wave generated by the rods will be transmitted to the trans-
ducers which subsequently produce an electric signal. The
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resultant signals are fed to a timing and calculating device
which calculates the position of the trajectory of the bullet
and permits the position at ~hich the bullet hits the target
to be displayed on a device such as a cathode ray tube.
A further proposed arrangement is described in U.S.
Specification 3,489,413 (Groder) and this specification dis-
closes the use of bi-directional transducers each adapted to
detect whether a shock wave generated by a supersonic prcjec~
tile and impinging on the transducer originates from the left
or right of the central axis of the transducer. The specifica-
tion describes an arrangement in which a plurality of trans-
ducers are arranged in a row adjacent the base of the target,
and a further plurality of transducers are arranged in a col-
umn adjacent the side of the target. In view o~ the nature of
the system it is only possible to determine which broad area
of the target was impinged upon b~ any particular bullet since
it will only be possible to determine the position of the bul-
let by reference to the two transducers at the base of the
target between which the bullet passed and the corresponding
two transducers at the side of the target. Thus the system
only has very limited accuracy and furthermore the transducers
provided at the side of the target are susceptible to damage
by inaccurate firing.
A ~urther prior proposal is disclosed in U.5. Speci-
fication 2,925,582 (Mattei~ a~d this specification discloses
the use of four transducers spaced around the periphery of a
target area, signa~s derived by the four transducers when a
bullet is fired at the target being fed to an appropriate cal-
culating and display device adapted to calculate and display
the position of the bullet. The calculating device initially
determines the duration of the shock wave detected by each
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transducer, since the dura~ion of the shock wave increases
with increasing distance from the origin of the shock waves.
Signals representative of the durations of the shock wave con-
trol the beam scanning circuits of a display device. This
prior proposed arrangement suffers from the disadvantage that
at least three of the transducers are exposed to fire from
the marksmen and are thus susceptible to damage. Furthermore,
the levels of accuracy obtainable with the system described in
this U.S. specification are not very h.igh.
It will be appreciated that the pxiox art discussed
above discloses the general use of transducers to detect shock
waves present in a rigid target or to detect airborne shock
waves generated by a projectile such as a bullet, but all the
prior proposed arrangements suffer from either the disadvan-
tage that the arrangement does not provide an accurate indica-
tion of the precise position of the bullet, or the disadvan-
tage that the transducers are in a position in which they may
be damaged by bullets hitting the transducers. Furthermore,
some of the prior proposals suffer from the disadvantage that
rigid targets must be provided which must be replaced regular-
ly to ensure that shock waves are transmitted satisfactorily
through the rigid targets.
At the present time in training a trainee marksman
to hold his weapon correct,ly it is necessary for a trainer to
observe the firing position adopted by the trainee marksman.
If the weapon is held incorrectly the rounds fired by the
trainee marksman will not hold a consistent group but will
spread at random over and around the target. Consequently
the trainer may be able to assess the faults of the trainee
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marlisn~an. llo~ever, i~ the :Eau.l-ts of the trainee marksman
are consisi.e~llt the trainer may reach -the conclusi.on that
the sigh-t3 o:~ -the weapon of a trainee maricsman are~ incorrectl-y
ad;just~d, allcl may adjusl; the s:i.ghts of -ihe weapon. Conseq--~
ently, althollgh the rounds ~:ired by -th.e trainee mar]csman
Inay then group at the ce.ntre o~ the target, the -trainee
marksiman may still be holding the weapon incorrec-tly.
It is f-llr-ther to be appreciated that, at the present
time~ there is no way o:~ knowirlg what the trainee marksman
actually sees over the sights of the weapon, and the present
inveniion also seeks to provide an apparat-us to enable the
image viewed by the trainee marksman to bc viewed by a
trainer or to be recorcled.
¦ ~urthermore it is to be appreciated that correct
breathing is an importallt part of accurate marksmanship, and
thus the present invention also seeks to provide an apparatus
~or monitorillg the breathing of a trainee marksman and also
for monitoring the pulse-rate of a trainee marksman.
The present invention seeks to provide an improved
target in which the above described disadvantages are
obvi.ated or reduced.
According to one aspect of this invention there is
provided an apparatus for determi-ning i.nformation concerning
the trajectol~r of a supersonic projectile passing through
2~ a predeterminecl area, the apparatus comprising at l.east three
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transducers located spaced adjacent an edge of the predetermined
area, each said transducer comprising a member of rlgid material
having a convex surface exposed to an airborne shock wave gener-
ated by the supersonic projectile, and means for providing an
output signal in response to detection of such a shock wave by
said member, the output signal providing means being connected
to said rigid member such that the distance of the path between
any point on the convex surface and the said output signal
providing means is constant so that the output signal is gener-
ated at a pre-determined time relati~e to the instant at which
the airborne shock wave impinges upon the said convex surface,
regardless of the location of the point on the convex surface
that is impinged by the shock wave, there being means to
measure the time delays between the output signals generated by
each of the transducers, and means adapted to calculate, from
said time delays, information concerning the trajectory of the
projectile.
In this specification the word "transducer" is used to mean
a device capable of providing an output signal in response to
detection of a shock wave generated by a supersonic projectile.
Preferably, the transducers are located adjacent the lower
side edge of the predetermined area, and conveniently the trans-
ducers are each adapted to be mounted so that the shock wave
impinges directly on the transducer.
Preferably, each transducer may comprise a disc shaped
member of a piezo-electric material and each disc preferably has
a diameter of approximately 5 mm.
In one arrangement the plane of each disc shaped member is
substantially vertical, but the plane of each disc may be hori-
zontal or may be inclined.
Advantageously each transducer comprises a member of rigid
material for transmitting said airborne shock wave to a piezo
electric material element in firm contact with the base of the
said~member~
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said member having a convex surface exposed to the shock wave.
Preferably said member is hemi-spherical.
Conveniently each transducer comprises a member of an
insulating material having a recess to accommodate a disc of
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piezo-electric mater~al lla-ving con~uct:ive coa-tings oll tho t,~10
oppoaed face~ thereof and challnels accommoc~at:;ng conduc-tive r
wires connected to said coatings, the base of said member
of rigid materia:L being secured to tlle piezo~clectric disc.
preferably -the member of in~ulating material is
surrounded by a sleeve of an electrically conducting rl~aterial
to act as a ~araday Cage.
~dvantageously each transducer is mounted on a rigid
structure, the transducer being mounted in an appropriately
shaped block of acoustic de-coupling l)laterial, the block being
clamped or otherwise secured to the r:igid structure.
I Preferably said acou3tic de-coupling material comprises closed
cel~ polyethylene foam.
I The predetermlned area may be a target area which
1~ ' may be provided with one or more targets. The information
calculated may be the position of the trajectory relative
to the target area, F
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In an alternative embodiment of the invention the
transducers may be mounted in apertures formed at predeter-
mined locations in a support panel, the transducers being di-
mensioned to be snugly engaged in said apertures, the panel
being provided with means for absorbing shock waves. The
panel may comprise a sheet of metal with sheets of sound ab-
sorbing material secured to the faces thereof.
Preferably means for absorbing shock waves or sound
may be located between a rigid target in said target area and
said transducers.
Means may be provided for amplifying the signal pro-
duced by each transducer, and such amplifying means may com-
prise initial amplifying means and a threshold comparator which
only passes si~nals having a predetermined minimum value. The
output of the threshold comparator may be amplified with a
linear amplifier, and the threshold comparator may be adjus-
table. Four, five, six, seven, eight or nine transducers may
be provided.
In one arrangement in accordance with the invention
a plurality of target areas are located adjacent one another,
and there is one array of transducers located under the tar-
get areas, the calculating means being adapted to select sig-
nals from the transducers providing an output signal in res-
ponse to detection of a shock wave generated by a supersonic
projectile fired at one of said target areas. The said array
may be a linear row of transducers or may be two staggered
rows of transducers.
Preferably means are provided for storing tempora-
rily information concerning the time of generation of a signal
by each transducer, and means are provided for subse~uently
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transferring the information to a computer constitutiny the
calculating means.
The storing means may comprise counters which are
started and stopped in response to the detection of a shock
wave by predetermined transducers, the counts stored in the
counter subsequently being transferred to the computer. Al-
ternatively, a clock signal generator may be provided to pro-
vide successive signals representative of successive instants
of time, latches being provided adapted to store the signal
generated by the clock signal generator at the instant that
the latch receives a signal from an associat~d transducer;
means may also be provided to supply a signal indicative of
each latch, and to transfer signals from each latch and the
means providing a signal indicative of that latch to a buffer.
Further means may be provided for transferring signals from
the buffer to a computer memory when the memory is able to
accept the information.
A plurality of groups of transducers may be provided,
each group being associated with one of said storing means.
Each group of transducers may be associated with one bank of
targets.
Preferably said computer comprises means for scan-
ning information signals fed to the computer to select groups
of signals likely to be derived from a single shock wave, and
means for calculating the position of a projectile from each
of said groups of signals. The calculating means may comprise
a pre-programmed general-purpose device. The computer may be
adapted to control the display of information on a visual dis-
play unit, and a television camera may be provided to gene-
rate a display signal from a visual image of a target. Means
.ay be provided for detecting when a portion of the targetimaqe corr~s- ...
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ponding to the ccllculated position of a projectile is
being displaved, and for inverting or otherwise modifying
the display si~nal a-t'that instant.
Preferably means are provided for determining the
co-ordinates of the point of the visual image being scanned
by the televlsion camera at any instant, and
for comparing these co-ordinates with the co~ordinates
of the position of the projectiles as calculated by the
computer. ' ''
' The computer may also be proved with means for
printing output data or punching paper with output dat~
In one embodiment of the invention the transducers `~
a~e all located adjacent a lower edge of a target are-a and
are concealed from the flring point by means which cannot
bo penetrated by said project:iles.
A rigid target may be provided in said target area and
each target may be provided with means to move the target
from a concealed position to a visible position and vice
versa. Also means may be provided for illuminating the target
provided at said target area to permit shooting to be conducted
after dark.
Thé transducers and rigid target may be mounted on a
-trolley which can move along a predetermin0d -track to permit ',
the position of the target to be adjusted.
2~ ~ computer may be'provided adapted to control and
monitor movements of the targets. If a plurality of
targets are provided, the computer may be provdecl with means
for displaying -thc condition of each,target. Alternatively,
radio control meall.s are p~ovided to control rrlovement of the
tar~e~t.
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Accordirlg to another aspect of th:is inve:ntlon the-re
is provid~d a transducer for detecting an air'borne shock
wave, the -transducer comprising a dome member of` substa:nt-Lal:Ly
rigid ma-terial and llaving a. convex surface adapted to be
exposed to the shock wave, the dome member transm-ltting
the shock wave -to an elenlent which p.tovides an outpu-t
signal in response to the shock wave, -the e].ement being
connected to the base of the dome.
Preferably the dome member is hemi.~spherical.
Conveniently the elemen-t adapted to provida said output
signal comprises a disc shaped member of` piezo-electric
material, one planar face of which is connected to thc base
of the dome menlber.
In one embodiment the disc is bonded into a recess
formed in a housing formed of insulating material, the 'oase
of the clome being provided wi.th a prejection dimensi.oned to
pro;jec-t into said rece,ss and engage the disc of piezo~electric
material . ~:
Conveniently opposed planar faces of said disc are
20. coated witl~ an electrically conductive material 9 and electrically
conclucti.ve wires are connected to the coated f~.ces~
P:referably shielding means are provided to shiel;l the
trnnsdllcers so that the regi~n of space from which the
tr~ansducer~ may raceive sh.ock waves is bounded by a single
pllne, and the shielding.means may comprise a rigid linear
melDb~r extending in front of and a~ove the transducers.
Conveniently two substalltia].ly linear row.s of transducers
may be pro-vided~ each row of transducer~ cornprising at leas.t
three transducers J the two rows of transducerc, being
arranged ill sllbstalltlally a common plane.
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~ccorcl;n~ l;o a1lo-tl1e-r ca.spec1; o:r` t~li.s :Lnve)~ti.on t1-Jere
i.s provide~ a trl:irling equipl11cnt ro:r train;.ng personncl,
saicd equiplnent coln~r:ising a weapon~ means for detecting lhe
pressure applied to predc-ternli.ne p~rts of thc ~-eapon by a
person hol.ding t~c weapoll, and rneans for recording or
displaying the pressure applled to the weapon.
Preferab]y a visua:L display -un:Lt ma-y be prov;.ded to
display the pressure appli.ed to the weapon comprising means
to d-.splay a representation of weapon and means for causing
parts of the represen-tation to have colours representative
of the pressure applied to the correspondlng parts o:~ the
actual weapon.
According to a further aspect of this invention there
.~s provided a weapon for use in training personnel in the art
of marksmanship, said weapon being provided with means
for generating an image representa-tive of the image viewed
by the marksman across the sights of the weapon, and means
for recording the generated image or for en~ab:Ling another
person to view the generatecl image.
2~ Preferably there is p-rovided a device for monitoring
the breathing of a marksman, said device comprising a belt
or the like adapted to be worn by th.e marksmatl and means
f`or measuring the tension within the belt to ascer-tain the
quantity of air within the lungs of the marksman.~ -
In order that -the inven-tion may be more reaclily
understood and so that further features thereof may be
appreciated, the inveIltion will now be described by way of
example wi-th referencie to the accompa:nying drawings in whichs
Figure :L :i.s a perspecti.ve view of a rif].e range provided
with a.n apparatv.s in accordance will~ the pre.se]lt invention;
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Figure 2 i5 a cl:;agram indicating the posit:ion o~
the trajectory Or a ~rojecti:le relative -to four transduce~s
and relati~-e~ to co-ord;.nate axes;
Figure 3 illustrates hyperbolic co-ordinates defined
by units of time dif:Eerence between the instant of reception
of shock waves by adjacent pairs of transducers;
Figure 4 is a hlock diagram of one embodiment of
the invention;
Figure 5 illustrates an arrangement of staggered
transducers and the corresponding intersecting hyperbolic
co-ordinates;
Figure 6 illustrates a transducer element;
Figure 7 illustrates the output signal generated
by the transducer of Figure 6;
Figure 8 is an elevational view of four trans-
ducers;
Figure 9 is an exploded perspective view of a
preferred type of transducer;
Figure 10 is a cross-sectional view of the trans-
ducer of Figure 9;
Figure 11 is a perspective view of an arrangement
for mounting the transducer of Figures 9 and 10;
Figure 12 is a circuit diagram of an amplifier
associated with the transducer of Figures 9 and 10;
Figure 13 is an elevational view illustrating the
shock wave generated by a supersonic projectile;
Figure 14 is a representation of the trajectory
of a projectile and the detection of the resultant shock
wave by a transducer, points being identified thereon to
assist in mathematical analysis of the situation;
Figure lS is a block diagram of another embodi-
ment of the invention;
Figure 16 is a block diagram of part of the
embodiment shown in Figure lS
Figure 17 is a block diagram of another part of
the embodiment shown in Figure 15;
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~igllrQ L~ is a block diagrarl1 of another par-t O:r the
embodi.men-t S}lOWII in Flgure 15;
ï~igure .1.9 is a repre.serltation of the trajectory of a
projectile allCJ tl~e detection ol the resultnnt shock wave
by a transducer, points being identified thereon to assist
in mathematical analysis of the situation;
~igure 20 is a perspective view, partly cut away,
of a panel for supportin~r transducers;
~igure 21 is a side view of a target and associated
transducers i:Llustra-ting a block of so~nd absorbing material;
Figure 22 is a perspective view of another embodiment
of a rifle range in accordance with the invention;
~igure 23 is a diagrammatic view showing the shock
wave generated by a bu].let during its flight;
~igure 24 is a perspecti.ve view of a row of
transducers shielded by a shield;
~igures25 to 28 are diagrammatic views o.f a shielded
transducer and a shock wa~e generated by a bullet 9 these
figures illllstrating the situation at successive instants
~0 of t:inle;
F:igure 29 is a perspective view illustrating a
preforred axra~ of transducers;
l~igure 30 is a side elevætional view of a weapon
in~accordance with the inverltion suitable for use in a range
in ~ccorclance ~ith the present invclltion, providecl with
pre~3ure-sensitive transclucexs, and a fibre optic device;
~igure 31 is an illustration o:C a display su.it~ble
for use whon t.h.e weapon illustratecl in Figu]7e 30 is uti].i3ed,
~i.gu.re 32 is a diagra.lDlDatic per3pective view of a .
trainee ma.rksll~an utilising the weapon illustratcd in l~igure 30 :
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aMd also proviclod with means f`or mon;.tor:ing pu]so an~
breathing rates;
Figure 33 :i.s a bloc:li circui-t dlagram o:~ the apparatus
utilised for monitoring the marksman lllus-trated in Figure 32;
Figure 3lI is a flow dlagram O r opcration of the
apparatus illus-trated in Figure ll and
~igure 35 is a flow diagram o~` operati.on of the
apparatus illustrated in ~igure 15.
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~-~~ DET~IL10 D~S~R]P -ro~ Oi~ T~l~ P~ '}~r`~ E~11301)I,~ TS
~efarri1~g -to Figure l of the accompany:ing d~awings
a rifle range in aecordance ~ith t11e ~reserl-t inventio-n
eomprisQs a plurality of~ firing points :L intendecl to be
oecupled by -trainee marksmen 2, and a corresponding number
of targets 3 intended to be fired at by the -trainee marksmerl.
The targets are shown in a single bank~ but a plurality of
banks of targets spaced at increasing distances from the
firing points may be provided. Loca-ted in front of the targets
is an earth bank 4 or ot}ler protective device and located
behind the earth bank 4, and thus out of the line of sight
o~ the trainee marksmen 2, are a-t least three transducers 5,
the transducers being arranged at spaced positions adjacent
the ]o~er edges of` the targe-t ~nd being adapted to sense the
shock ~;aves generated by bullets fired at the targets. One
S long row of transducers may be provicled in front of all the
targets, or a separate group of transducers may be provided
~or each -target. The transduce;~s 5 will be described in more
detall hereinafter. The transducers 5 are connected1 by
mean~s of appropriate cables 6 to a co~lputer 7 or other suitable
ealeu~ating device which is aceommodated in a control room 8
uti~ ed by the range controller. Tlle computer is adapted to
ealeullte the position of eaeh round fire at each -target 3
~h~n the shoek wave generated by the round is deteeted by the ;~
tra~1sducers. T11e position of` eaeh bullet may be displayed
2~ on a visual display unit 9 in the control room and 011 a
visual display unit 10 provided at each firing point l. Thus
the trai1lee marksman may see ~here each particular round
.in~p~ ges on the target. ~f spectaGor.s ll arc- to be present,
a large visual display device 12 may be eonnected to the
.
compu~er 7 to enal~le the spectators 10 to vie~ tho progress of tbe
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2~64~
~ shooting. In aclcl~t;oIl, or a~ an al~rnlltive to t'he
provision o~ -the d;sp]ay Wl:its, print out dovicos or papor
punching devices ]3 may be operated by the computer 7 to
providc a printe(it or punchod paper out;pul; inclic~tlng the
point at which eacll bullet impinges upon the target 3.
It wi.ll be appreciated that wi-th a system o~ this
type it is not necessar,v to use rigi.d ta.rge-ts, and the only
requirement of the target is that the target should be
visible to the tralnee marl~sman to provide an aiming po,nt.
Thus it ls not necessary to utilise personnel to repair
targets or indicate the position at which incli.v:idual rounds
impinged upon the target, It will also be appreciatcd that
since the transducers 5 are l.ocated behind the ear-th bank 4,
t~e only possible ~ay in which the tran~ducers can be damaged
al a result of` firing is as a consequcnce of a ricochet, and
such r:icochets are very unusual. 'rhe probability of any
transducer being dan~aged is extremely low. As will be
explained in more detail hereinafter, utilising a system of'
this type it is possible to ob-tain great accuracy and, in
fact, with a -target area o.f 6 ft. by 6 ft. it :is possible to
calculate the position of any builet, imp:inging on Lhat; target
area with an accuracy of greater than ,1 inch. It is
bel.ieved that if appropriate s-teps are taken this.accuracy
1' may be improved.
¦ 2~ Now that the invention has been broad:Ly clescribecl~
the apparatus will be described in more detail.
. In one relatively simple embodimcnt of the in.vention
I it is asswned -that the shocl~ wave generated by a supersonic
¦ p.rojectile expands in a direction perpend:Lcular to the
i 3 trnjectory oI` th.e projectile, arld th.us a plural.:ity oI` de-t;ectors
.
.. -:
- ~ . , . : . :~
.. , : . ~: ,. . - .
. ,, . ~
, . :: ,,
," ..
2~ Z
in a si.ngle plane per1?endicular to t}l~ -trajecto~y will detect
the shoclc wave at -tinles dependen-t solely upon the distance
of` the respective d~tector fronl the trajectory.
In an 0mbodiment o~ the inventi.on of thls type at
least four transducers T , Tl, T2, and T3 as .shown in Figur~ 2
are arranged on a horizontal line e~tending from lef-t to rlght.
The distance from tran.sducer T to transdueers Tl, T2 and T3
ean be considered to be xl, x2 and X3 respectively. If a
bullet passes over the transducers at a general point P(x, y)
on eo-ordinates based on transducer T , the distanees from the
pair x, y to the transdueers To, Tl, T2 and T3 will be
lo, ll, 12 and 13, respeetively.
It is assumed that the trajeetory of the bu]let is
p rpendieular to the vertieal plane eontaining the transducers,
l~ and also tha-t the transducers will reeei.ve the shoek wave
from the bullet sequentially and with time delays varying in
dependence upon the preeise trajectory of the bullet. From the
signals genera-ted by the transdueers, further signals tl, t2
and t3 ean be ealcula-ted, tl being the time delay between -the
reoepti.on o~ the shoek wave by transducer Tl and transducer T ,
(this figure being negatlve ir transdueer To reeeives the
shoek wave b~ore transdueer Tl), anci t2 and t3 corresponding
time delays ~or transdueers T2 and T3.
It will be apparellt that
t~ ~lo) /Vn (~
t2 ( 2 o) / - (~2)
t3 = (13~ n (~)
wllere Vll is the velocity of the shock wave perp0nd;.eular to
the traJectory of` the bullet.
~17--
- : . :: .,: : . , ; .
We }~ave that 12 ~2 ~ x2
12 y2 f x2 ~ xl2 2xxl
122 -- Y + X + X2 - 2xx2
123 _ y2 ~ x2 ~ x2 - 2xx3
Ther~ ore
2 _ 12 - (11 ~1o)(ll + lo) = (11 10)(11 ' ~ 1
2 0 2 0)( 2 ~ lo) ~ ~12 ~ 10)(12 ~ lo ~ 2~1o)~X2~2~;X
B2
13 - 10 - (13 10)(13 + lo) = ~13 ~ lo3(13~ lo ~ 2~10)=x3 -2~-x2
' ' . ''' '' ' ~
Substitutin~,r i'or ( 11 - lo) by tlVn etc
~ .
:10 ~r2' tl ~ 2Vntl lo = Xl 2XX1 ~1
Vll t;2 ~ 2Vnt2 lo - xz 2 C2_
y;~ t2 + 2V t3 lo = X3 2xx3
Mu L l;~ plyillg Cl by t2 and (~2 by tl and subtracting: -
Y~ tlt2-(tl- t2) _ xlt2 ~ x2tl ~ 2x (x2t;L - xlt2)
1.~ Mult.iplying ,1 by t3 and Cl by tl and sul:)tract:ing:-
Vn tit3 ( t~ 3) = Xlt3 ~ ~3tl * 2x (x:3tl ~ ~ t3) D2
n~ricling DJ. ~ 1)2 and 7~carrangillg g:i V3 S
~ 1 (-~3~ 2~3)t2(t,.~t2)~ t~ 2t23~,3(~ t3,~! .
~X i; -~-t3)l2(tl't2) ~ 2tl-x~t2)t3(t;l 3) J ~u
.. . .. , . , . .. . ; . .. .... . .
, ` ~ , ., ; ~
., .
.. . " ,
... ,, .., ~
.. .. ; .
( ) 3L~Z8~
Cyclic rear:rall~ement of terms wi.ll also y:ield:-
f~ 1 2 x2tl)t3(~2~t3)~ (X3t2~X2t3) tl(t2-t )
l(., lt2 x2tl)t3(t2~t3)- tX3t2-X2t3)tl(t - L; )
and
x - 1 1(x2~3-x3t2)tl(t3-tl)- (xlt3 x3 1) 2( 3 2)
l~ 2 3 x3t2)tl(t3~tl)- (Xlt3-X3tl)t2(t3-t )
411 the value~ on -the ~ight o~f the equation are known~
- ! . . ,
'~
' ~
. ~ ~
. ~ ' ' ~ ' ' " ' ' ' . ' . ; .
.
.'
' . . , '
,~
9_ . '
æ
c~la~in~ rounc- x ~Te Inay rr:it;e rrom nl
y2 xlt2(X1~2X) X2tl( 2
. tlt2(t]~t2)
Cyclic rearran~enlent of terms w:ill also yield
j y2 _ X2t3(~c2-2~{) ~ X3t2(X3
~ ' ` t2t3(t2-t3)
,
and
v2 _ x3t](X3-2x) - Xlt3(X1~2X)
_____~__
. ' '
Thus ~e can measure the erfecti~re spced of sound; wllich
enables the val~le of y to be determined as follows :
Usin~r Cl t~e may ~rite
-
o ~ (~;l(Xl-2X) ~ Vn-tl) ~ (X (x2-2x)-V2t2)
' 4v2t2
, _ (X3(X3-2~c)-vrlt3)
. 1~V2.1;2
~ J
}lence we can fi.nd y:-
.~ Y -- [ 1 _ x
. As lndica-ted above in an appara~tus in accordance
with the present inventlon a plural.~ty of transducers are
1 located beneath a target at wllick a tl-aillee marksman is to
~i.re~ Consi.der an embodilnerll; o~ the invention i.n whictl at
le~st tllxee t;xal-sdllcers are arranged in a hor.i.zorltal line,
. _20~
,, i .
'
8~
the transducers bein~ equispacc~l. Tl~e trarl.sdllc~rs l~, 1.5, .1.7
are illustratecl scl~ematically in Figure 3. The tr~nsdueors
each genora-te a signa~.~the time a-t wh:ich a shock wave
generated by the bullet is detected, and the signals are f~d
to a timing device which calculates the time delays between
the detection of the sllock wa~e by the first transducer and
the last transducer. Referring to Figure 3 of the drawings,
it can be seen that. if the shock ~ave is detected by the
transducers :L5 and 16 simultaneously then the trajectory
Or tlle bullet must lie on the cen-tral vertical line too.
However, if the difference i.n time of detections of the shock.
wave is one unit o~ time9 the transducer 16 receiving the
shock ~ave before transducer 15s then lt will be appreciated
that the trajec-tory o* the bullet is somewhere on the
1~ hyperbolie line'tOl. Similarly if the shock wave is detected
by the transducer 15 one unit of -time before it i.s d~tected
by the transducer 16 then the trajectory of the bulle-t must
be on the hyperbolie line -tl . I-t will readily be appreciated
that a ~amily of these hyperholic eoordinates-may 'be generated,
simi.lar hypcrbolie coordinates bèil~g defi.ned by tha combination
o~ transdueers 16, 17 and a:Lso by the combination of transducers
l~, 17.
In one specific embodimellt of the invention based on the
foregoing mathematieal a.nalysis, five transdueers J8--22 '~
(as sho~l in Figure ll) are uti.lisecl whieh are mounted in
'position so that they are spaeed apa:rt in a row beneath
thc target area. A typical transducer construc-tion that may
be use~ will be describc-d hereinafter. The output of each
transducer i~ fed to a ~e.spc-cti~e one o~ arilplifiers 23~27 to
ampllfy the OUtpllt slgr~ l. A typlcal ampliI`ier ci.:rcu.it wi.l.:l. be
, - . - . . ~:
: , : ; ~ : - . :, :, : .
'~ descr~ eclllereillar~Qr. Cvunters ~8~ ~9, 30 arl~ 31 ~l:rc COllrleCte~-
respectively to tlle oul,pl.lt.s of ampli:C:iers 23, Z~l, 26 and 27,
A Iogic c(Jn1;rol ~levice 32 is co,~lccted to the OUtpllt of the
amplirler 25, ancl i,s also connected to provide a signal
to eacll of the courlters 2c", 29, 30 and 31 when a signal i.s
present OIl tha output of a1npllfier 25. I~ach coun~er may be
of the type 7l~l91 sold by Texas lnstruments. Each counter
is comlected so that if it initially receives a signal
~rom the respective amplifier it will count at a
prede-ter~ ined rate in a negative sen.se until the cont.rol
device 3~ :receives a s:ignal from amplifier 25, anci then the
~ counter w:ill stop. Alter.llative].y, i.f the counter initially
receives a signal frolll the co:n'trol de~ice 32~ then the
eounter ~T:ill count at the prede~termined rate i.n the positive
sense unti.l the courlter receives a signal from the associated
amplifier,
Thus, as a bullet or other supersoni.c projectile
passes over the transducers 18 to 22 and the shook ~ave is
.detected sequentially by the transducers, the counters 28, 29, 30
and 31 will store counts representative of the time dirfereilce
betweeIl the instant of detection of the shock wave by
tra~sducers lS, 19, 21 ancd 22 respectively and transducer 20.
A computing device 7 is connected to the outputs of the
eounters, and includes a memory for storlng the counts. The
25 eomputjng device 7 scans the s~,ored tlme delays and
calculates the time difference between each adJacent pair
oI` transducers. ~omputlng device 7 then compares
the calculated time dif~ercnces and se].ects the group of four
adjacent transducers for wh:ic,h the calcul.ated time cli~`:[`ereIlces
', .
--22-
. , ' ' ' .
., . ~ ': . ,~. '', '
'
-`` .~2~ 2
are smalles-t in magnitudeO The comput;ng devi.ce then
proceeds to calculate the position of the trajectory of the
bul:Let from the meQ~sured values for tl, t2, and t3, and known
values for xl, x2 and X3, ;.n accordance with equations given
above. The measured values of the di.stances between all
the transducers (ie xl, x2 and x3) are permanen-tly stored
in the computer memory. Once the position of the bullet is
detcl~mined, thi.s posi-tion can be displayed on an appropriate
d:isplay device 33, prin-ted by ~ printer, or otherwise
utili.zed to indicate the shooting accuracy oP the trai.nee
marksman .
In the embodiment of the invention presently being
described the computing device 7 can be considered to calcul.ate
the position of the trajectory of the bullet by determining the
l~ hyperbolic coordinates of the trajectory. For accurate results
to be obtained it is necessary either to use at l.east .four
(prcferably five) transducers and utilise information derived
from each of the transducers to assist in calculating the
posltion of the trajectory~ or it is necessary to provide
the computer ~ith inforl~lation concerning the velocity of thc
bullet and the velocity of sound i.n air. Thus, in certain
ci.roulllstances it may be adequate to utilize three transducers.
For example, where a certain amount of inaccuracy can be
tolerated, and/or where match ammunition is being util.ized7
the computer or other calculating device can be pre-programmed
` or otherwise supp].ied with the bullet velocity and 1he sound
~l.ocity.
If four transdllccrs are ll-tilized there is a vertical
elro:r zone extending above tl).e transducers. I.f a bul.let :is
rired throu~ll this parti.cular error zone there is a hi~,h
23
Z~6~Z
probahil:ity that the comput:ing dev.i.ce will err~neously caLculate
the posltion o* thc bullet and the crror may b~ as large as
several ~eet. Thus, even :if ~our transducers are util;.zed,
and the -target is so pos;.tloned relative to the transclucers
that the error zone does not; coincidc wlth the target area,
if a trainee marksman misses the target an~ the bullet passes
throug]l the error zone it is possib].e that the computer will
calculate the positlon of` the bullet erroneously, and will
inclicate that the bullet hi-t the targe-t, while the bullet in
real;ty lllissed the target. T.his error zone, is, in actual
j fact5 symlnatrically located between two of the transducers and
thus, when a bullet passes through thls error zone the two
transducers with respect to wllich the error zone is symmetrically
located will each detect the shock wave substantially
sin~ultaneously. It is possible to take account of this *act
and to prog~ramn~e the computing clevice to recogni.se a
situation where the bullet has passed into the error zone, i.e.
-to recognise the situation ~here the two transducers in
question receive the shock wave substantially simultancously,
nnd to provi.de an appropriate di.splay or print out. Tllus
if -the error zone is not on the target area the compu1;er is to
inclicate that the bullet was a "~niss" or to indicate that the
bu~llet passed through the error zone. In any event a bu].let
pa~lssing into the error zone would be disregarded and would
2~ llOt be recorded as a "hit".
S.i.ncc the existence of` the above described error zc,ne is
clisadvantageolls, it is preferred to u.tilise at :Least f`ive
transducers as il:l.ustrated in I~lgure 1~ I* such an arrangement
is utiliz~d there are five different notional groups of ~our
30 . l:ransduce-rs -that can be selected from the five transclucers.
- ' . ~ - , ,, :
.
: -
` ? 1 1~2~2
The col]~putin~ device 7 is aclapt~d to store signals r~prc-sentati~e
of tllc time O:r recepti.on of the sllock. wave by each of the
transducers 5, to calcu:l.ate the posl-tion of the projecti.le
by using one prima-~r group of four tran.sducers. Howev~r~ when
the computin~ device ini.tlall-y selecte a group o.~ four
transd~cers, it will determ:ine wllet}ie.r -the bullet or projectile
passed through the error zone of that particular group of four
transducers. If so, the computing device rejects that group
and selects a ~urther group of four transducers from the five
and repeats the calculation. Of course, in such a situa-tionS
it would be possible for -the calculation to be repeated using
each of the relllaining four of the five possible transducer
groups, and for the computing device then to take an average
or mean result, thus fur-ther reducing the error.
. In utilizing a five transducer arrangement of this type it
-is possible to provide reasonable accuracy over a large
rectangu]ar area located immediately above the row of transducers.
The only zones where accuracy cannot be guaranteed are located
at the very side edges of the rectangular area above the
transduccrs. If it is desired to eliminate the possible errors
tllat.may occur wh.en a bul.let passcs through t;hese zones, the
transclucers may be selectcd or adjusted so that each transducer
OIlly detects shocl~ waves frorn a proJectile wi.th:in a pradeterminecl ;
~distance of the transducer, this predetermined dis-tance being
2~ se~ected so -that bu]le-ts entering i:nto the zones where errors
are likel-~r to occur are not detected by all -the transducers.
I~ the shock wave g~nerated by a bul:l.et i.s no-t detected by all
the transducers the posit:ion of the bullet is not calculated.
Al1;ernat;vely, th.e comput.ing clevice may be programmec1 to detec-t
~0 when a ~ll].et passes wlthin the error zone ancl to provicle an
-2~- .
~ ; . : . ~ . , . ~ . , ,
~ ;:. : : : ;
`'`'`~'`` ~2~6~æ
ap~ropriat:e outl-)u-t~ since lr the bu.llet doe.s enter the error
zone the various time dirferences be-tween the instants of
recepti.on o~ the shock wave by the ~ar:ious transd~cers will
have a very recognisable pattern.
In yet another embodiment of the inventi.on, where the
. invention is utilized on a range having a large number of
targets, it i5 possible to provide a long row of transducers,
the transclucers being located beneath t'he targets. Whenever
a bullet is firecl at a target the shock wave generated by the
bullet wil.l initially be detected by one transducer or by two
transducers substantially silnultaneously. Depending upon wh.ich
tr~nsducer, or transducers, inltially detect the shock wave,
a group of four or five transducers surrounding that initial
transducer or transducers is selected by'the computing device.
1~ The times o~ shock wave detection by those transducers are
utili~ed as a basis ~or the calculation.
While it has been indicated above that certain error ~ones
appear ~here transducers are located in a straight horizontal
~ e, it is e.nvisaged thatthese error zones Inay be reduced or
or obviated i~ the transducers are arranged, as sho~.~ in
~i~urc 5, in one upper horizontal row 34, 35 9 36, and one lo~er
hor:iY.ontal ro~ 37, 38, the transducers 37, 38 in the lower
~oW being o~fset with regard to the transducers 34, 3~, 36 in
tlle upper row. Thus the transducers define a letter "W".
:Ct wi.ll be apprecia-ted tha-t -the hyperbolic coordinates de~:ined
by the transduc`ers when dis~osed in this way intersect at
righ-t angles or at an angle dependant upon the angle o~ inc;.dence
bet~een the arills o~ -t'he "W", thu.s pro~-ldillg a h-igh degree o~
accuracy. Some o~ these hyperbollc coordinat.es are illust.ra-ted~
0~ course, :i.n ad.dition to the i.ntersec-ting hyperbol-ic coorcli.nates
~6
.
, ,; . .
. ` . ` . ~, . .
.. .. . ....
` , , : ,.;
i , . . ... ; ... .
. ' . ,. ~
..... ..
. ` . . .. . :
... . .. .. .
... . . ...
- ~2~2
as illustr~ted, the tllree transdllcers 34, 35; 36 in the
upper :row can be utilised in precisely the same way as the
three -transd~lcers illustrated in Figure 3, and thus many
intersecting h~perbolea can be dQ~'ined.
In practicing the presen-t invention it is poss:;ble to
utilize as a -transducer, a flat disc 39 of a piezo-
electric material. Such a transducer may bé located in a
hori~ontal posi-tion as illustrated in Flgure 6. Such a
transducer does possess several disadvantages, however.
If ca bullet 40 is fired to the right of the transducer the
subsequent shoclc wave 41 will impinge on the edge or corner
o~ the transducer 39, and the transducer will be compressed both ;
in a vertical direction and in a horizontal direc-tion. The
resultant output of the transducer will have a wave form
substantially as~illustrated in Figure 7, which is a negative
golng sinusoidal wave I`orm 42 ha-ving a small positive "pip" 43
at the leading edge. I-t is desired to measure the time T
illustrated on the wave form, and it is very difficul-t to detect
this time ~ accurately since the amplitude of the "pi.p" 43
dopends upon the precise position of a bullet, ls di:~ficult
to d:istinguish :from baclcground noise, and can even be absent.
Tho comput;ng device is provided with inI'ormation concerning
the position of the transducer, this information being the
precise position of the center 44 of the transducer. All
calculations are performed on the assump-tion that the
'transducer is at this particular position, and that the
ou-tput signal ~enerated by the transducer is indica-tive of tlle
insta~ at ~hich the shock wave arrives at this part:icular
position. The transducer, ho~ever, provides an outpu-t l~ith
a prede-torminec1 re~ponse tlme as soon as the shocl~ wave imp;llges
.
~27~ ~
` `" ~L~%~ L2
upon the transduce:r. If a bu]let 1l5 passes vcrti.cally
above the transducer 39 the shock wave imp.ingcs clirec-tly on
the upper surface o~ the transducer, generatirlg an
appropriate outpu-t si.gnal. Now it ca~ be seen that the
trajectory of the bullet /lO Pired to tb.e right of the
transducer is ~ur-t;her from the point ll~ than the trajectory
of the bullet 45 passing immediately over the transducer.
However the distance between the transduceb~ surface
and each o~ the trajectories of the bulle-ts 40, 45 is equal
to a distance L. Since the transducer provides an outpu-t as
soo~ as the shock wave impinges on -the transducer, the -tillles
between -the bullets passing and the output signal being
generated are equa:L. Thus -the output cf the tr~nsducer
would sug~gest that the trajectories o~ the bulle-ts 40, 45
l~ are equispaced from point 44, which is not correc-t. In
other words 9 a slight timing error will be generated
and the calculated trajectory of the bullet pa,sing to the
ri~ht of the tr~lsducer will be c].oser to the point L~4 than
it is in reality.
Thi.s particular disadvantage can be overcome by
diSpOSillg -the transducers in a vertica:l. orientation so that
~ the tr~lsducers are in the form of vertical discs ll6, 1~7, 48,
1i9l~(as sho~ igure ~), the planar faces of the discsbe ng directed towards the trainee marksman. As a bullet 50
2~ passes over the discs and the resultant shock ~lave is
generated the shoclc wave will always impinge UpOIl the periphery
oP each discg and the poin-t o:~ impingement of the shock wave
on each disc will be an equal clistance ~rom the centre or
origirl oP the disc. A cons-tant timing error will thus be
3~ i.n-troducecl i.l~.tO each signal generatecl by each transducer.
.
.
:,' ' ':' ': :
:, :, . ~ . ' ',, :
f ~ ~28~
Since on~.y the tinle d~ rerences are used as a basis fol tha
calculati.ons tllis cons-t~nt error will bo cancelled out.
However, oricnting the discs in a vertical position will
not obvia.te the problen, o:C the posi-tive plp 113 at the beginnlng
of the output signal 42, therefore, in the present i.nventionS
i.t ls pref`erred to provide each trans~uce~ with a dome of a
so.lid materi11 having a convex surface exposed -to the shock
waves~ the planar base of the dome being in lntimate con~act
,witll the transducer material and being adapted to transmit
shoclc waves ~rom the a-tmosphere to the transducer. Ir a
hemispherical dome is utilized, provided that the a.xis of the
dome is pointing vertically upwards in front of the target, or
is directed towards the trainee marksma.n, or is at an orienta-tion
~etween these two limiti!lg orientations, the shoc]c waves
1~ generated by the projectiles flred at the target will always
strike the periphery of the hemispherical dome tangentially,
and shock waves will be transmitted radially through the dome
directly to the center o~ the transducer. Thus a constant
t:im~ g error is introduced, this timing error being equal
to tlle t:ime ta]cen for the shock wave to pass f~oln the periphery
o~ the hemispllerical dome to the center thereof~ and cas
indicated above such a constant t:iming error will be of` no
consequence.
It will be appreciated that -the hemispherical dome serves
to preven-t or m;.nimi.ze the genera-ti.on of the positi.ve-going
pip 43 at the beginning o~ the wavc form genera-ted by the
transducer, and t]~us -the output o~ the transducer now :resemb.les
more c:Losely a sinuso:idal wave formO However, it :i.s :i.mport~lt
that the instant Or commencemellt of this si.nusoidal wave ~orm
be measured w:i.tn great ac~cl~lac~ a~ld thus it :i.s preferred to
: , . .
u-tili~e a trallsducer -that will have a very fast rcC.iponse~
thoug.ll not necessarily a large response. It is found that
i~ t1le respoIIse -time of a s_ries o~ piezo-clect~ic discc. of
di~ferel~t si~e are comp~tred, th~ rc6pons~ tirl1e :is a function
of tl-le diameter of th.e c~:;sc, the su1aller di.scs havillg a faster
respnnse til11e. ~owevera it has been found that a response
ti1ne o~ all discs with 5 mm diameter or smaller are
substantially equal. It is to be noted, howevL~r, that the
amplitude of the output of such a disc is proportional to
its s:;ze, and it is ~or this reason that it is presently
preferred to utili~ie a ciisc having a diameter of 5 mm, since
such a size pro~ides the fastest response tirn~ wl-th the ~-
highest amplitude output signal. This si.æe of disc is
also preferred since the output of a transducer provided with
1~ such a disc has a ~requency much higher than that of i~ny noise
or interference likely to be encountered and thus such noise
can be filtered out. However, it is envisaged that smaller f
di.ameter discs may be preferred for reasons of improved accuracy.
With reference to ~igures 9 and lO of the accompanying
drawi.ngs a preferred transducer for use in comlection wi.th
the present i.nvention colr1pr.ises a transducer element
cons:is~.ing o~ a disc 51 of piezo-electric material such as,
fo~r example, lead zirconium titanate. The disc 51 is l mm
thJlck ancl 5 mnr in diamete.r. The opposed planar ~aces of the
2~ d:isc 5l are providecd with a coating o~ a conductive rnaterial
52, such as silver which may be provided in any convenient
way, such as by vacu~m~ deposition Two electri.cally conductive
wire3 53, 54, I'or exa1nple, ot' copper or gold9 are com~ected
to tlle center o~ the lower sur:~ace o.~ the disc and to the
per:ip]lery of thc ~pper s-lrf`ace o.t` th.e disc by so:Lderi.ng or
: ,.
- - - - - . : , . . .. :
.:., .
: :~ ' , ~ . ,'; ' . 'i; ' , ,, : .
-: ~ ...... :: :: , .: ;.
2~
by ultrasonic bonding The clisc 52 is then fi.rmly mour.l;e-l in
a housin~ l~hich eomprises a cylllldrica] n~ember 55 havill~ a 5 mrn
diameter recess 56 in one end face, tlle recess 56 having a depth
of 1.5 mm, the recess 56 also being assoelcated ~ith an axial
bore 57 e~tending tl-;rough the rr.ernber 55 to aeeommodato the wlre
53 pro~ided on the lower sur~aee of the piezo-elcetrie meinber.
A seeond bore 58, parallel to bore 57, is formed in the periphery
of the member 55, this bore 58 being adapte~ to aeeomr,lodate
the wire 5L~ and termillating in ~n open reeess 53 adjacent the
main reeess 56. The me~nber 55 may be ~ormed Gf Tul`no~ hicll is
a pllenolic resin borlded fabric, thi.s materi.al being re~dlly
obtainable in cyli.ndrical formO The housing may be machilled
froln this materlal, al-though alternatively, the housing may be
~ormed of a two part phenolie resin sueh as that sold under -the
Trade Mark "Araldite", the resin being retainecl in a eylinclrica.l.
aluminium ease 60, and subsequently ~eing macllined: If tho
latter e~pedi.ent is utilized the aluminium ease 60 may be
eartlled to provide a ~araday cage to mi.nimize no:ise. The
piezo~electrie ~naterial and wires are bonded in-to the member 55
with an aclhesive sueh as ~raldite or a cyano acryl:ic impact
acUlosive. Two small bores 61, 62 are forllled in the lower surfaee
of the Inember 55, and electrically conducting plns 62, 63 are
mounted in the bores. The wires 53, 54, protruding from the
` lower ends of the bores 57, ~8 are soldered to the pins, and an
2~ adhesi-ve or other suitable setting Inateri.al is utilized to
retain all the elements in posi-tion and also to secure a
soLi~l}lcmi~plleri.eal dome 65 to the traMsclueer. Tlle dolr~ ma~
be machilled :~rom alumini.um or east from a ;ettlng resin
mat:e:r.ial sueh a.s that solcl ~mdor the Tlacle Marli "Araldite"~
3 The cloms 65 ~rei`erabl~ has an outer diameter Or about ~ mlr~ hieh
is equa:l.
31- .
: ; ,: . . : : : ~
r' `,
to the dilmeter of the housing. ~ centrally disposed
projection 66 on the base of thc dome member is adapted
to contact the p;.ezo-elcctric disc 51 and has the
same diameter as -the disc 51. ~l-ternati~ely, the dome
and the memeber 55 may be cast as a single integral unit.
The pins 63, 64 protruding from the base of the
holder may be connected to a co-axial cable, and the entire
~nnectlon ma~ be encapsulated in soft rubber. The coaxial
cable may be short (i.e. up to 1 me-tre in length) and is
eonnected te a suitable amplifier adapted to amplify the output
signal generated by the transducer. In an alternati~e
embodiment of the invention the ~ins provided on the holder
are eonneeted directly to a printed circuit board upon which
is mounted the amplifier, the printed circuit board being
1~ potted on to the base of the hous:ing.
The housing eouplHd with its assoeiated transducer,
is mounted, as generally deseribed above, in front of the
~argHt, and it is important that both the housing and any
cable emerging from the housing be aeoustieally decoupled
from any suppor~ of any other rigid structure that eould
possibly receive the shock wave detected by the transducar
bofore tho shock wave is rec.eived by the hemispheriea:l. dome
p~ovi.ded on top of the transducer. Thus, if the transdueers
a~e mountHd on a rigid horizontal framework i.t is i.mpor-tan.-t
2~ that the transducers are acou.stica.Ll- rl.~-eoupled from sueh
a framewvrk. The transducers may be mo~ ted on a blocl~
of any suitable acousti.c de-eouplin~ medium, such as an
expanded polymer foam, or a comb:inat;ioll of polymer foam and
metal platH. The mos-t preierred material is closed oell
3 foam polyetl-lylene, tl-lis material be:ing solcl uncler the Trade
~ . :
-32-
.. . , ,; :,. ..
, : ' ' . :' !, . ~ , . ~
, ' ' ' ~ , ' ' , ' .'. '' ' . ', ': ' ' ' .
,:' ` ' ; ' '' . ' . ' ~. ' '~ ~ , " ; ' ' :
' ' , . ,~ '' ~ ", ~ . ' ' '
z~2
~lal-h :'Plast:i~o-te" by ~alcelite Xy.l.onite IimitedO 0~ cour~;o,
many other aco-ustic de coupline .llaterials may be used suel-
as g.~ass fibre cloth or mineral wool.
'l`he -transducer may be mounted by taking a ~lock 67
of acoustically coupli.ng medium as illustrated i.n Figu~e 11,
~ormlngr a hole or recess 68 withi.n the block o~ material
dimensioned to accor.~odate the transducer and ~lol~er and
inserl;in~ -the housing into the reeess. The 0ntire block
may thln be clamped in any convenient way, sueh as by clamps
69 to a suit~ble framework or support 70, -these it~ms being
~illustratecl sc~lemati.eallyO
hen the transducers have been positioned relative to
~e target it is neeessary for inforsr.~tion concerning the
p ecise positi.on of each transdueer to be suppli.ed to the
1~ eomputer together with in~ormation eoneerning the position
o~ eacll target'relative to the transduee:rsO The appropriate
distances may be measured carefully and the appropriate
information may be fed to the transdueer~ or other nlethods
may be used for supplying informatlon to the eomputer~ For
~ exanlple~ instead of measuring the dis-tanee betweeII the .
trallsducers with a ruler or the .l.ike~ a rod of metial may be
loeated so that the rod of nletal is touehing eaeh of the
trallsducers, alld an ult~asonie pulse may be propagated alon~r
the rod of''metal, the time of arrival of the pulse at each
2~ transdueer being measured and reeorded by the computerO The
. eomputer is provided with the spt~ed of the ultrason:ie pulse
- wa~e along the Isletalli.e rod, and eonsetlllently the computer
is able -to ealc~lla-te, wi.th ~ high c~egre'e o~ accuracy~ the
l>reei.se pos:ition of eaCIl tr~nsducerO
3 [-t ~i.ll be apprecii.l-tecl -thclt when bullets aro :Li:recl
, . _ .
~2 ~
. ....... ~ ,~
.. . . : " . .,. - , : .: .
,,
86~2
towards t.h~ targets tho position oE tho bul:ie-t is measu-etl
relative to the tr.~1sducer, and i.-t is this position that is
eventua]ly displaytcl by I;he computer. Thus it is important
that the compu-ter bc provitled wil;h precise lnformation
concernir1g the position of` the target relative ~o the
transducers.
Tl1e an~plitud~3 of the signal generated by each Or
the transduccrs as described above will depend upon the
velocity of the bullet, the precise na-ture of the bulllet,
the distance of` the bullet from the transducer, and many
~other variable factors.
l From the transducer signal it is necessary to obtain a
- s:i.gnal whic11 can be utilized to operate a means which measures
the time a-t which the shock wave was detected by the tr~s-
l~ ducer. It is accordingly desired to change the analog trans-
ducer sig11al oE ~igure 7 having an imprecise leading t-~dge,
into a digital signal. The transducer signal is :Eed to i~n
ampli:Eier which provides a digital signal havin.g a f`ast
lead:ing edge, the amplifier being triggered by a shock wave
but not tri~gered by any no:ise. The pref`erred amplif:i.Qr 71
~ sho~l i.n Figure 12 of` the accompanying drawings a ant~ i-t is
to bt3 noted that the signal is supplied to the ampli-fier along
t11e coaxial cable 72, the two cores o~ the coaxial cable being
f`ej past various biasing resistors to the input o.-E a di.f`~er-
2~ ential amplif`ior 73. T11e ou-tput oE tht-~ di~:Eerential amp].ifier
73 is AC coupled. to a trig~er threshold comparator 74 in
whic11 t.he ~:ignal is compared with a predetermi~td re~`erence
s.ig11al to prevQnt l;ke onl;ixe apparatus bei11g triggered by
IlOi se rather than a ShO ck wave '~.t3 trigger tllreiho].d
3~ . c:oll2paratQI 74 ma)~ be adjustetl to ~et t11Q th~.~es11o1.d se11sit-
ivil:yO Tilo ~utput Or t11Q compal-ato:r :i~ ainp1iried w:ith a
. . .. . . 3t
:. , ,: . , . :~, , , ~ :
,: ~: .- , . . ~:
linear ~mpli~ier arrallgeJI)cnt 75~76S77 and ~n ampl:iI:i.od s:igncl:
is prov:ided at outp~.t 78.
Th~ component re:[erclices shown in Figure 1~ o~ the
aecompalaying drawings identify the components utilise~l in
S the preferxed e~.bodiment o:f tlle ln-vention, theso eomponl~nts
being military grade components available f`rom Te~as
Instrumen ts .
The output o~ the amplifier 71 can be considere~ a
di~ital signal, since it indicates whether tlle transducer
output is greater or less than the prcdetermined threshold.
As already i~ldicated the mathematical analysis given
abo~e is based on the assumpti.on that the shock w~e generated
by a supersonie projec-tile expand3 perpendieularly to the
t~ajectory of` the projectile; while embodimen-ts of the
invention based on the above mathematical analysis ha~-e
pro~en satisf`aetory, their aceuracy cannot be impro~ed over
eertain limii;s.
It h.as now been appreciated that when a bulle-t is
f`i.red ~rom a gun such as a rif`le, at each instant o~ -time the
supersonie bullet generates a shock wave~ each shock wave
subsequently expanding spherically at a linear rate~ Fi~re
13 of the aeeomp~lying drawings illustrates the trajec-tory of`
a bullot ~lcl indieates the positions oecupied by the bullet at
inst~n-ts ~ le ~i~ure also illustrates the sphcrical
2~ shock wa~r~s genera-ted by the bul]et at those instancec; 3 the
shock waves all being il].ustrated at the instc~.t g4 -C-t will
be appreeiated tllat the di.~meter of` the shoek wave at the
position occupied by the bulle-t at t:ime ~4 i.s nil, whe:reas the
d:i.ameter o~ the .shock wa~e generated by the bl~l.let at t.ilne
.is rela-ti.~rely :Largev It will also be appreci.atecl ~rom
l~:i.gllre 13 o~ the accompar~yi.ng drawings, -that the en~e].ope o:E`
35 :
,. I
.. ; . . .
~286~2
the spl~ores defines a gellcrally con:ica.1. shock wave, and
since a shock wave ls generated at every installt such a
con.ical envelope i5 generated.
~igure l4 i.llustratcs the tra;jectory of a bullet or
other projectile approaching the target~ and also illustrates
the shock wa~re genera-ted when the bul3e-t is at the posi-l;ion A
being detected by a sensor CO The bullet impi.Ilges on the
target at the point B.
It is possible -to cons:ic1er the situation fro.~ a
mathematical approach, initially assurning that at a tin1e T
the bull.et is at a position P somewhere on the trajeotory,
and also ~y constructing a perpendi.cular from point D on
the trajectory to the sensor C. The shock wave generated
when the bullet is at point A on the trajectory is detected
by the transducer C.
Conside~r a bullet tra~elling along the trajectory
PADB ultimately striking the target at B. It is requi.rcd -to
find the coordinates of the point B in the -target plane with
respect to the origin O of the coordinate system.
P presents the position of`-the bulle-t when a timing
perio~ is started. The shoclc wave ~l:ich eventual.ly triggers
~ the sonsox at C ori.g:inates from point A on the bullet
tr~jectory. D is a point on the trjaectory such tha-t CD is
pe ~ endicular to AD.
2~ 1 It is ass~ed that the bullet trajectory is linear
over the (relatively shor-t) distance PB. Let T be a unit
..vector in the di.recti.on of the trajectory.
From the properties of shock waves from supersonic
pro;jectiles, ~e ha~e that
3si~ o _ s .~ .. cØ.. (3.)
b
~6 --
-: ,
. - , ~:.......... :
2~6~
- where ~ is the velocity of sound and vb ~s th~J -~elocity
of the bulletO
Now, the time for the shoclc wave to reach the sensor
at C is given by
t - time ~or bullet to travel ~ time for shock wave lo
from P to A -I;ravel from A to C
Starting with this initia:L mathematical concept it is
possible to derive a vector equa-tion relating the varlous
voctorial parameters and t.
A similar equation will hold for each of the sensors
.in the scnsor array, When the time t is lcnown for each sensor
in the array it is possible to solve the equatiolls as a set
o~ simultaneous equations. Xn one case the equations will
earh contain five unlcnowns, and thus five equations must
1~ be,solved simultaneously. The equations rnay be solved
iterative:Ly.
A rifle range tha-t is based on such a ;nathematical
approach will now be describedO
l~igure 1~ of the accompanying drawings illustrates tlle
- 20 al;rallgetnont of transducers 7~ Oll a range havine a plurality
o~ lanes 80 flnd a plur~llty o:L target ban~ 81, The trans~lucers
' ' ` ' ., '.:',' ,' . ~
,
,
,
, ! I .
'' ' ' `' ' ~' ` , , . ~ ,,
79 o~ each target bank 81 are connected to a tirning arrar~cr.l~n~
82 (uhich will be descl:ibed hereinafter) and the output o~ each
timing arrangenlent i9 ~ed to a b-~ffer 83~ Thus referring to
ure ~ of th.e accompanying dra-:/ing~ therc ~re three ban.ks of
ta~gets 81' whi.ch provid~ si.gnal.s ~rom thc t:ransduc~rs to ~hQ
three timing arrange~ent~ 82~ and thus to th.ree buffers 83. The
buffer~ are interrogated sequentiall~ by computing device r~ and
when any in~ormation is available at the output o~ a buf~er 83,
then that in~ormat~on ;.s transfcrred intc computing device 7
and subsequently the bu~fer is cleared. Each target bank is
providod with a long row of transducer~ lo~ated in front of
each target~ There is not a specific group o~ transducers
~ocated in front of each lndividual target. It is to be
~ppreciated that in utilising an arr~lgement in which inform-
1~ ation ~rom each bank of transducers is stored in a buffer,
with the buffer~ being interrogated by a single computing clevice,
the amount o~ wiring needed on. the ra~ge is minimized~ since
othel~iise each transducer would need t~ be individually
connocted to a computing de~ice.
Re~erring to Figure 169 each timin~ arrangement 82
compr~se,s a group o~ tristate latches 84~ each latch being
connoc~ed to the output of the ampli~ior 71 a~ociated with an
individual transducer. I,atches 84 ~ay be o~ the type sold b~ ~.
Telas Instruments ~lder the ref'orence number 74363. Each of' the
2~ trlstate latche~ 84 is connected to a.n output o* a 24 bit cloc~
signal gelleratc)~ 85~ generator 85 provicling~ successlve Sigllcal9 .
indicat.ive of` the precise tim~. A new signal is generated eve~-5~ ¦~
ten nano seconds. The a.rrangemc-~nt 1'S such that ~hen. the digit~l
si.~lal i.s provided f'.rom the al~pl:ifier 71 as30ciated Wit~l a
t~ansdllcer to a la-tch 84-~ th~ latch will ~ecord the 24 ~ cJcsc3{
. ,.. ,. ~
:' ~' , '' -,.. ' . : :
,, :
,, ~ ~ , .. . .
,6~
9ig~nal prcs~nl; on th~ output of the 2l~ bit clocl~ sig~al
gonerator 85 at that in~tant, The digita], sigllal from the
ampli.fier 71 is also fed~ ~imultaneou~ly, to a control dc~ice
86 which sub.sequently causes tllc si~lal recordcd on tho latch 84-,
together with a signal permanent:Ly rccordcd on a rcad ol~ly
memory 87 associated with th~ l~tch, to be transferred to the
buffer 83. The signal stored on the read'onlr memory 87 is a
signal which identifies the transducer a,ssociated with that
particular :Latch 84. The buffer 83 i a "first in~first out"
t~pe device and temporarily stores the informatioll~ The
information stored in the buffer 83 comprises the time signal
temporarily stored in the latch 84~ and the transducer ic3,entit-,y
slgnal permanently stored in the associatecl read onlr memory 87
Once this information has been acceptéd-by the ~uffer 83, a
1~ further control signal is sent to the latch 84; the latch then
clears and is ready to store another signal from the c].ock
signal generator 85 on receipt of a further shock wave from the
associ.ated transducer. Thus~ the buffer 83 will storc a large
um~er of separate items of information~ each item of info~nation
compr.ising a signal identi.fying a particular transducer and a
slgnal represenlative of the time of receipt o~ a shock wavc by
tllat particular transducer. Of courser if t~o successi~e shock
waves are detected by the same transducer~ t;hon two succe.ssive
signals will be temporarily stored in the assooiated buffer9
~5 comprising the same transclucer identiPyingr signal9 but having
different signals representative of the time of receipt Gf a
shock wa~e by that tran3ducer.
I~hen a sig~al. stored in the buffer is a~ailable in tlle
output of one ~uI`fer 83, a sig~ilal is ,orwarded to cause
'~O compul;i~g clevice 7 to l.nterrog~.t;e eacll of the buffc,r~ acc~p-ting
~ -- 3~ ~
:, . :, . .
86t~
lnformat:ion ~rom thta ~uff`er ~3 that has info~n~ltion presen-t On
its outputO Referrill~ now -to Figure 17~ information ~ro~n the
bv.~fer B3 i3 fed to ~ first mini~computer 88 a~ 1rell as to a
memory 89 present in the computing assembly 7. These components9
and othe~ components presen-t in the computin~ assernbly 7, are
connected together by a maxibus 90 (shown in Figu~e 17 in thta
accompan~ drawings)~ The arrangement operates in real time1
that i9 to say, time not shared bet~een the various components,
but the components optarats independently of each other~ and
the components may thus operatta simultancously. The mi~i-compllter
88~ 1~hich may be a Texas Instr~ents T~IS 9900 computer associated
with a local memory cornprisillg an Intel 2102 memo~y~ initially
scans the data received from the bu~fer and compares the various
tinles of reception o~ the shock waves by the transducers. ~rom
tllis lnitial comparison various "groups" of received signa].s
a~e identified7 each such group of signals comprising shoc}~
wave detection times wi-thin a prede-termined range and -thus beln~
si~nals that are possibly derived from a single projectile. ~or
taxanlple, as a projectile passes over the transducers the shoclc
wa~e ~enerated by that proJec~ile will be detected ~y ~ive or
9:iX ~l'allSdUCerS of a long row o~ transducers located ~rLder t'ht~
tnrgets at wl-:;ch the projectile is aimed. The~e transducers will
all detect the shock wave within a comparatively short period of
time, and thus the signals detected by the transducers can easily
boldistinguished ~rom the si~Lals received by thta transducer~
~oin a subsequelLt projectile, since the si~Lals recei-ved from
tht2 su~set~uen-t projectile ~ill be much latar in -time.
As lndicated a~ove~ the ml~i~computer 88 seletcts li,kel-y
groups o~ receinved sigllals and ~teteds ths signaJ.s -~o a special
purpoCle calcu:iator or p~e-programmecl general p~rposta compul:tar
6~;~
91 having a P~0~ (progr~mmed readout memory) which subjec-ts the
input d~t~ to the prodoter~ined mathQ~Iatical operations de~cr-ibecl
abo~re9 and provides an output s~gnal represcntative of the
po~ition o~ the tra~ector~ of -the projoctile.
It is pr~ferable that the programming of unit 91 i~
cont~i~ed in the hardwar~ of the device, so that no software
progra~nme is necessary~ Thus the device can operate at a
very high s~e6dJ Such an approach is feas-ble ~or this
port.ion: of` computi~g arrangement 7 since uni-t 91 will only
be required to perform one mathematical f~nction However9
it i5 t:o be appreciated that a softl~are-programn~ed computer
could be used, provided that such a co~np~ter was able to
operate ~lth su~ficient speed. A~ter the maths unit 91
has calculated the position of ~he projectile trajectory
relativa to the target ~rea, that infvrmation is fed to
memory 895 and from there to a visual dlsplay assembly 92.
The visual display assemblr 92 comprises mean~s fOI'
generating a signal which~ when fed to a cathode ray tube~
causes that catho~ ray tube to display a rep~esentation o~
a target. :Ref~rrlng to Fi~ure 18, the pre~erred ~eans for
genorating such a signal comprises a closed circuit television
cnmela 91~ c3sociated with means 9~ for projecting an image on
a photogrlplli.c slide 96 into the camera. l~lc camera 94
operates in the usual way and thus produces a video signal
2~ r~p~esentative of the image on the slido 96~ A190 present
o~l the sl.ide 96 are vari.ous ~narks o.r lines defln:ing X and Y
axes~ tho position o~ the tar~et be:i.ng known ~ith regard to
tihese axes. Part o~ -th~ vi.deo s:igrnal from the cam~ra is
~ed to t~.o sepQ:rate ~e te~ctor ci~ouit~ 97~ 98~ wllich are
adapted t:o detec~ tha posi-tiorl o-f the heam ~canni.rl~r ~he -ta:rget
~.. ~,,
` ~ ` ` '
~ . .
64;~
iII the camera at any instant~ the dctf~ctor circuits 97~ 98 bo:ing
connectcd to a blallking de~icf 99 adapted to bla~ out tllat part
o~ the vide~ sif~rnal which rela-tQs to thf3 marks de~ining the axes~
Th~ls the resulting vidoo signal o~ lin~ 100 comprises only a part
o~ the ~ideo signal generated by the camera 94~ that being the
part vf the s.ignal representati~e of the image of the ta~get.
The signals generated by the X detector a~d Y detector are also
~ed to a ~eparate comparator 1019 this comparator being
provided with informa-tion, ~rom the computing device 79 compris
ing the precise position of each proJectile det~cted by the
system. The comparator 101 co~.pares the posi-tion of the
p~ojectile wi.th the signal~ from th~ X detector and Y detector,
and when the signals correspond, that is to say when the beam
in the camera 94 is direct0d at the area o~ the image projected
tO the camera 94 correspondi~g to the area of the target 011 thc
ra~ge that has been impinged by the projcctile, then the
comparator pro~idos ~n output signal which is fed to c~n
exclusive OR gate 102. T~e OUf;pUt of the blan~ 99 is fed
to n cathode ray tube 103 via the exclusive OR gate 102, and
it will be appreciated that the cathode ray tube wi.ll d.isplay
an .image of the target derived by the camera 94 .~rom the
slidc 96; and ~ill al.so display~ o~ that image, arear l~here
the color of the image has been re~srsed indicative o.f the points
of the target impingred upon by t~le bullets or pro3ectiles fired
2~ on the range. 0f course~ it is ass~ed that the bu110t or
projectile will implng~ upon. tlle target at the position calcul~
ate~ by the comput~r :from the informat.i.on lerl~red b~ the
transducers~
0~e ~l.sual d:isp1ay unit 92 Illay be pro~ided ~or a range
control].c~ and the xang-3 controller may sel~3ct any ~arget
o~ ~e plurali-l.y o~' t;ai~get.s on t;he raIl~e a.~ bf~in~, a -targf3-l; o
.. . , . . ., .,, . .. . i .
4;2
illteresl:, and then th.e visual d:i.splay wlitt ~rill d.:isplay a
represent;ation o~ tllat particulaI target and a represerlta-tion
of the posi-t:ions at which projectiles fired at that tal-get
hav~ impinged on thc -target, or passed by the target.
plurality Or such vi..sual displ.ly units may be provided ~`or
plurality of r~n~e controlle~s, and .indeecl, as envisaged
in tll~ openin~ para~raphs of t'h-is description an individual.
display Ullit nlay be provided for eacll trainee mar~sman so that
the markslllan Inay il~nediately see where each bullet goesu
It i.s en~isaged that in a range in accordarlce with
the invent:;on the individual. targets will eaeh ~e associated
with ~ meella~ism for raising the target to an exposed pos:i.tion
a~ld lo~rer~ -the target to a concealed position. These
mechanisms may ~e controlled by the compu~er assembly~ and
tlle cotllputer assembly may inelude a users programme store
104 Oil whieh a predetermined progran~ne of`lnovements of the
targets may be stored, the targets executing these predeterlr.ined
mQvelllents ~hen the stored programme is aetivated~ A second
~ mirL~colllp~lter 105 which again may be a Texas TMS 9900 eom]?utQr
,!0 may l~e pro~icled connected to the nlechanical cleviceiY 106 ~hi.c]
arc provided -to move the targets, tllis computer recording -the
pos:Lt;:ion o~ each part:icular target and c]leclcing tlle correct
~unetioning~ of` each particu:Lar targetO A rurther visual
display ~Ln:it 107 may- be provlded i.n such an embod:iment oI` the
invention, th:is display un:it displaying itnages dep:ic-l,lng~ the
~-arious targ~c-ts present on the range, the display present
on -the ~isual display unit at any part:icular tlme belng
ind:icative of the condition o~ each target, -tllat is to say,
whether l.lle tar~et i:.-> in clne rai.sed pos:ition oY~ ;.n tlle lo~ere~-
3 pos:il::io.L, .~ncl also inclicat:iil~, t;~)e nurl~er o.t' hits tha-c have
,
. , ~43~
.. , . , . , . . :
:
,. :.
- . : .: . . .
. .
.: '.
864;~
been score'-l on any par-tictllar -targetO It i:s envi~aged tllat
this particular v:isual d:Lsp].ay unit will t>a provided f->r a
suparvîsory ranga controller who may~ from con~iderin~r the
~risual display ~lit 9 a~se~ the precise condition of each
target present on the range, This visual disp:lay uni~ is also
adapted to indicate a mal*unction of any par-ticular target~
A printer 108 is also associated with the computer
assembly~ the printer be.ing operable to provide print-ovts of
any of the information present in the storeO A paper pu~lcher
may also be providedO
The main computer 109 which provides a controlling
function is preferably a computer ~old ~y Comput,er ~utomation
(Naked ~lini Di~ision) of Ir~ine, California9 as computer OS 1
4~10~ the users progran~te storage 104 is pre~era~ly a floppy
di,sc s~ib system model 1~566-XX as sold by Computer Au-tomation,
the main tnentory 89 is preferably a core mernory of` wp to 32 K
words as sold by Computer Automation~ and the preferrod printer
108 is a Centronix 306, also a~ailable from Computer ~utomation~
It ~Yill be appreciated that rllany modifications n~ay be
ma~e~ arld the computer may be provided with :~acilitie,~ ~or
calculati~g a score attrib~table to any particular projecti.le~
this score being d:Lsplayed Oll tho appropriato ~isual display
it.
~ ~lo targets uti].ised in a range in accordance with the
present in~ention may be static targets~ may be targots that
~lse and fall in rcsponse to command signals a3 sho~m in Fitg-ure
1~ or may merely be sprays of`~Yater or the lil~e with vi~ual
images replesent,a-tive oI' the targets projectad on -them, '~f
the ~.argets are of thc? -type that rise and ~all.~ the tar~rets ma~-
be remoto eontrollecl by ~ig-na:l.s oll a oable9 a5 d.eSCribC?d abO-~C?9
. ; , . ' ' . '',., . ','" , " ~ :
2 !36~2
althou~rh t;h~ t~rg~t~ may be con.trolled by radio ~i~nals,
'~Ae comA~uter may b~ operLlted to caus~ a tar6ret to ~all
briefl~r~ ene~er the target i5 a.ctually hit by a trainee
marksmaD.. F~rthe~more, while th~ invontion ha~ boen
described ~ith refer~n~e spec:ifically to a fixed rifle range9
lt is to be appreciatec. that the i.nventi.on may be utilised
in a ran~e ~here targ0ts mo~e along on trolley.s~ the
tr~ns~ucors also being mounted on the trolleys ln a fixed
position relative to the targct;sO AlterrAatively~ the invention
may be utilised in connection witll groun~to-air or air-to air
weapoA7~As tralnlng~ in ~hich case the transducers would be
~ounted on the droguo ~Yhich i9 the target~ .
h~n a range as described above is utilised for
~raining a large nunl~er of mark~men the computer which is
locatecl at a central control console may perform many functioIls
and tho precise functions performed by the computer may be
controlled ~y vario1l~ push buttons o~ the llke pro~ided on ~.
the control console.
Initially the oomputer ma~ be adapt~d to calculate
the position of each rol.md fi.red at oach targot and to
provi.de sig~1als to vis~al dlsplay units pro~i.ded a~jace7lt
each trainoe marksman so l,hat oach o~ the visual displa~
units displays a represe7ltation of the ta~get at which the
trainee marksman is aiming~ and also pro~ides an indi.catio
f the poll~ts at whicll the trairAee mclrksnl~l has hit tha
target in any particulal- firing session~ '~hus~ if a traînea
mal~ksman i9 to iire t~n rounds at the -ta:rget~ as t~e rounds
are successive l~r fired a-t the target s~o tho position of impact
oi` t,he rourAds 0.71 the ta:rxet may ~e dl~played on the approp~:iate
vi.su~l di~pl~r ~n.it,
. ~ ~5
.. . ... .
,
.. .~
. I ~ , . . .
L2~36~Z
Of course~ near-misses can also be disp].ayed uI)oll the
viLsual c~isplay unit1 since such near-ln:isses ~ill be detected
by the transducersO At tlle enc1 of a shooting session if
the marl;sm~n has beon reaso~ably accurate in his shooti.ng
~ there should be ten points mar]ce~ on the representation of
the taret~ indicating precisely wh.ere the rounds have hit
~he targetO It is possible that the various po-ints di..splayed
on the display unit may be associated with numbers indi.cating
the precise order in ~hich the rounds were fired at the
target, thus permittirlg the marksman to assess whether his
accuracy ~as improving or not during the shooting session~
The computer may also calculate for each target fo~
e~ch shooting sessi.on in the overall dimension of the
~'~roup" as fired by the training marksmanO These figures
l~ may also be displayed on the individual display unit 9 provided .
~or each trainee marksman. Alternatively, the number of
"hits" alld tlle number of ~misses~ may bc recorded and displayed~
o~ the score obtained by the marksman may be ~isplayed.
It is envisaged that the computer 7 may be progran1med
.o draw tlle attention of the range controller 1;o any trainee
mclr]{sman ~ho is firing very irlaccura-tely to enable the range
controller to provide that -trainee marksman wi-th instructions
or advice. The central control console is provided with a
. display device 8 enabling the trainer instantly to vie~ a
2~ representati.on of any one c)f the ta:rgets~ thi.s rep:resentati.on
corresponding prec:i.sely with the representation sho~ on the
visual display of the appropr:Late trainée marl~sman. Th~s the
t~-aine~ lay mon:itor the progress of each trainee Inarksnla~
l`he prlnter 13 may merely print the score and group:i.ng
3 o1~tc.i.ned L~v each of t]l.e ~.rainQe mark~;men duri.nf~ a ,hoot:i.n.~
":
LZ8~
~ sessivn, or the pxintt-3r may be operate~ -to provide a p.rlnl--
out re~resent~ltion.of any o.r all o.~ the targets includi.hg
a represelltation of the points at which each of the tar~ets
has been hiit by bulJe-tsO Such a prirlt-out may constitute
a permanent recorcl o~ the shoo-tirlg of any particulair markslnall.
The targcts 3 utiliscd with the present invention
may be static targets, and it will be appreciated that since
the targets onl~r function as an a.iming mark it will not be
necessary to replace any target unt:il the target is virtually
totally destroyedO It will also be appreciated that tlle
~invelltion may be used with advantage in connection with targets
that can be moved i`rom a concealed position to an exposed or
~ring position, and vice-versaO Targets of this type are
illustrated in ~i.gure l of the accompanying dra~ings, The
l~ invelltion may also be used in co~loction with targe-ts mounted
on trollies for nlovemeIlt along a predetermined track, the
- -tr~nsducers also being mounted directly or indirectly on the
trolley ror mo~ement with the target~ 0~ course, the invention
Inay be ~Ised ln conjunction with man~ facilites, such as ligllts
. to illuminate the target to perrnit shooting to be contlucted
a~ter darlc, antl means on or adjacent tlhe -target to si.mulate
retaliatory fire, Such means may be controlled by the
computer to be operatcd in response to a shot fired at the
target but ~.~hich is a near miss. Many further possibilities
will suggest thelllselves to tllose skilled ~n the art"
~ 'rhe Inal-henlatical analysis given above presumes that
the aiF in ~]hicll the projectile is fired is still, but if the
range is an open ai.r range the poss:ibility al.ways e~;is-ts that
the t~:;nd may be blow:LngO Thc following imathenlatical arlalys:i.s
3 ta];es aCCOUD t Or th.e e~`fect of ~incl~
~ ~7
.. . . . . . ................................ .
,~ ' . .. : . :, .
2~6~
Referriny to Figure 19 a bullet travels along the
trajectory PAB, even~ually striking the target at B, whose
coordinates are to be found.
The shock wave which eventually triggers the sen-
sor at C initiates at point A on the bullet trajectory.
P is the position of the bullet when a timing
period is started, i.e. P represents an arbitrary orgin of
tlming .
o, a point in the target plane, is the origin of
our coordinate system.
Now let the total time for the signal to reach C
from P be t, t is made of the time taken for the bullet to
reach A and the time taken for the shock wave to reach C
from A, Let these be tl and t2 respectively.
We can regard the shock wave motion as being a
spherical expanding wave front in moving air, In tim~ inter-
val t2, the centre of the spherical disturbance has moved
from A to R due to the effect of wind, while the disturbance
has expanded to radius RC.
Again it i5 possible to define a vector equation
relating various vectorial parameters and the sum of tl and
t2 .
For example such an equation will relate the time
of arrival of the shock wave at a sensor C~ to the position
of the sensor and the coordinates of the bullet hit position
in the target plane.
A similar equation will hold for each of the sen-
sors in the array, and sufficient sensors will allow equation
to be solved for the various unknowns.
In practice iterative methods may be ado,pted for
solving the equations.
-48-
. ~ ,~, ,. , " , .
- :
~. ~ . . . . .:
12136~Z
~'rhell ~ d i. S tak.cll iJ-ltO ~lccollnt th_r- are mor-~
unkno~TIl.s and thu~3lll0re itcms O:r i.npll-t data hav~ to 'be
availa~le to exlabl.fe tlle pos:ition of the projec-tile to be
de-termined. l~l)en solv:ine simultancous equa-t:ions ther3 h~ve
to be ac many equa-tions as there are urLknowns~ and thus d
large~number o~ time differences have -to be measured i:f
accurate results are to be obtainedO
¦In an alterIlati.ve approacll to the problems posed
by the e~istence of wind the speed and direction of -the wincl
may be measured and fed to the computer, and due account of
the willd speed may be talien into account in perforn~ing -the
necessa.ry calculations~
¦ One convenient way of measurlng the w:ind speed, or
a~ least me~suri.ng the erfectc Of tlle wind speed, is to
'provide one or more sound sourccs, such as sound emitting
transducers, located at predetermined poi.nts relative to the
transducer array. The sound emitting transducers are controlled
by the computcr and emit sounds of such a frequency that
tl~e~ may be del:ected by the trans~ucers, The transducers
~ ancl tilning devices measure -i;he time of detecti.on of the SOUlldl~aves ~enerated by the transcucers and these times are
compa~ed w.ith the times at which the transducers are cactiva-tedO
This comparison enables the effects of wind to be measured
accurately, and the ePfects of wind can t'lUS be monitored
instant by instant~ and at several pa.rts o~ the ran~e. This
is of parti.cular use in bl.u-tery concl:i.tions.
~L19,~
-.`, , ,: .
- . , " . ,
836~2
transducers enable accurate results to be obtained if the
projectile has a known oblique incidence and there is no
wind, six transducers enable accurate results to be obtained
if the projectile has an unknown horizontal component of
incidence and a known vertical component and there is no wind,
seven transducers enable accurate results to be obtained for
normal incidence and an unknown wind factor, and for known
oblique incidence and an unknown wind factor; and eight
transducers enable accurate results to be obtained for bul-
lets with an unknown horizontal component of incidence and aknown vertical component of incidence if there is no wind.
If the transducers are in the staggered, two row
arrangement, six transducers enable accurate resultsi to be
obtained if the projectile has a known horizontal component
of incidence, an unknown vertical component of incidence
and there is no wind, seven transducers enable accurate
results to be o~tained if the projectile has an unknown in- ;~
cidence and there is no wind, eight transducers enable
accurate results to be obtained if the projectile has a
known horizontal component of incidence, an unknown horizon-
tal component of incidence and there is unknown wind factor,
and nine transducers enable accurate results to be obtained
when the projectile has unknown incidence and there is an
unknown wind factor.
The numbers of transducers listed above indicate :
the number of transducers in the group selected bv the
computer, and timing signals must be received by the com-
puter from the
-50-
~ , , , , ' ' ' ' ' !
', ' ' ' ' ,', ;, : ~.
,' , . .. ~ ' ' . . ' ~:
` `` ~L~2~ 2
spcclficd n.~ ber o:f~ t;-lansdllccrs 1~: tllC position Or a
projeci,i.le. i.s to bc cal.culatcd accurat,ely in each of the
spec;.~ied set o:~ concl.:it:ionsO
Olll t]le fOregOillg it will be apprcciated thcat on
any occasions it i.s preferable to mount the tral~sducers i~l
.a staggerecl o:r non~linear arran~ementO One pref'erred method
of mounti.7l~ the trallsducers in this ~ashion is illustrated
in F:iglre 20~ The tx~ansducers are mounl;ed within appropriately
spaced apertures 110 :~ormed in a pane7. 111 compri.sing a
oentral rlg~id sheet of metal 112 tha faces of which are
pro~rided witll sheets of sound absorbing material 1130 The
domes 65 of the transducers protrude from the front face of
thc panel ll:L and are thus exposed to the shock wavesO
The reax~ encl oI' each transducer is provided with a radially
l~ extending flange 114 which is adapted to contact the rear
sur.~ace of th.e panel 111 to assist in locating tlle transducersO
The aperturc!s 110 can be accurately locatcd by drilli.ng the
ap~r-tures ~rith an appropriate jig. If the spacing between
the aperturcs tends to vary w:i.th varyi.ng temperature as a
rcsult of th(~rn~al e~pansion means may be provided to measure
the telnpel-al;ure and to provide compensati.ng i.nforr~ation to the
computer 7. Tlle panel 111 may be as 10ng as dosired, and rnay
accolmllodate as Inany transducers as required~
The transduce:rs may detect secondary shock. waves
2~ gcller.l-ted ~rllell thc projec-tile lnl~?inges on a rigld targret
located adjac,ellt the transducexs~ Tlle timi.ng de~rices, and thus
the conlputerS ma~ be ullable to disting~ll.sh bct~reen such
scconciar~y shocl~raves~ alld l,he shock ~ra~es that are ge~.exated
- p:r:imaril$~ by tlle projectileO Ti].us it is pre~er:red to local;e
tlle Ineans ~.ll support;lrlg 1;1le tra7lsduc~rs acljacent a blocl;
.
, ~ ; '. .::: .
'. : , . ,~ .
8~;~2
Or sound abs()rl:~inL~r ~late:r:ial or otller so-und absorb:LIlgr nled.i.unl;
locnted betw~en the t:ran.lclucerg and thc targret :L16 as sho~n
iIl Figure 1. A sh.ock wav~ trave:L:Ling in the direction of
arrow 117 ancl ge:nerated by a buli.et wil]. thus be detcc-ted
by -the transclucers, but a shock wave emana-ting from the
target and travelling in the dircction of arrow :L18 wlll
no-t be detected by the transducers. Thus -the transd-ucers
are in the shadow of -the member 115.
Figure 22 :illustratcs ano-ther embodiment of a ra~ge
utilising appa.ratus in accordance with the invention. One
set of transducers 120 are located below and in front of c?
set of static -targets 121. These transducers 120 arc
connected to the computer 7 by a land linQ 122 as described
~bove. In addition to the static -targets 121 there is a.
radio controlled target carrying self propelled troll~y 123
which is movable along a monorai.l track 124. The trolley
123 carries a target which is a representation of a tank.
A set oI` transducers 124' ar~ mounted on the trolley and
signals are set frorn the transducers 124~ to the computer 7 via
~0 a rad:i.o link 125. A second radio link 126 is provided to
enable control signa:Ls to be set to the trolley 123. ~any
othQr rang0s nlav be designed ~rhich utilise the present
inv~ntion, such ranges having static or trolley mou:nte(-l targcts,
targets that can fall automa-tically when hit arld -targets
~hat are especial:Ly illurninated for n:ight t:ime shoo-ting.
Fi.gure 23 illustrates the tra;jectory 127 of a
bullet ~hich passes over three transducers 128, 129, 1.30.
The bul1.et gellerates a conical.shock wavc~ as the bu:Llet
trcavels a.l.ong -the traiectory 127 and at the in~-tant a-t ~hi.ch
the bllllct reaches the point 131 the transducer 129 de-teicts
:,
: 51~ .
~.~
. , . ., , . ~.. ~ . .", . ~.. - , :,
t~e COlli.C~ sl~ocl; wavc generated by t:lle bullet. It can
easi]y ~c sllo~ tl~al, -the bul]et actuLI].].y irlitia-ted tlle
por-tion o:~ the shocl; ~ave detected hy l;he transclucer
129 when th.o bullet was a.t the pO:iXl ~ 132. ~n this speclri.c
e~ample, -the next -transducer -to detect the shock wave is
the tral1sclucer 128 wlli.ch detects the shock wave at the
:instant -tha.t the bulle-t reaches the point 133. It can 'be
sllown that the por-t:i.on of the shock wave detected by the
-tra,nsducQr ].28 was genera-tecl when -the bu].let was at the point
.0 134 on the trajectol~. Simi].arly the portlon of the shock
wave detec-ted by the transducer 130 will have orlgina-ted at a
differellt point on the trajectory of the bullet, and thus it
can readily be appreciated that each portion of the shock
~ave that is detected, in a typical case, wi~.l have been
generated at, a different point on the -trajectory of the
bul.,l.et, It has been noted that in many cases as a bullet
passes throu~l air the bullet is subjec-ted to retardation
md thus the bullet is -travelling at di.fferent speeds at
the various points on the trajeetory at which the bullet
.?~ aetually generates the shock waves which are subsequently
detectecl'oy the transchlcers. This leacls to an error and
under cert;aill circumstances the apparatus may provlde
inaccurate results.
In order to overeome this particular difficulty
a sh:ielding means is provided in ~ront of t,he transducers.
l~igure 2l~ illustrates an embodi.ment of the present inven-tion
ln whicll transducers 135 are arranged ln a li.near row and
a shield member 136 is provided which shields the transducers
135 from the coniccl shoel; wave gellerated i.n all regions
'30 of space e~cept a specifica.lly defi.xlecl reg:i.on ~l-ich ls bounded
~ 51B -
.. . : : ~ ~,;
. .
.
`: ' : '
: , :~
~ 86~;~
by a singlc,~ pla.ne. The shi.eld member 13G compr:ises a
sill~le silnple elonga-te member which ex-tends hori~or~ ta:Lly
in ~ront of -the -t~callsdllcer,s and whictl terminates almost
directly above -the tr~msduee:rs, Tllis ~:r~ectively derines 1.
a "hor:i~on" for the transducers 135 and the tra~sclucers can
detect a shock wave originat-;ng above this "horizon" but
cannot detect a shock ~ave origi.nating below the "hori~on".
The member 136 thus shi.elcls the -transdueers and sinee
the shock waves generated by a supersonic projectile
compr:ise the envelope of a plurality of success~ve spherically
expc~lding shock waves it will be appreeiated that the first
shock wave detecte~ by any transdueer 135 in tlle row o~
transducers will be th~shock wave genera-ted by the projectile
~t the illstant that it passes through the plane ~hjch is
defined by the row of transducers and shield rnember~ namely
the i.nstant that the projeetile rises above the "horizon". .:
Thus all the transdueers in the row of -transducers will
del;ect the shock wave that is generated a-t a single instant
during the flight o~ the projeetile arld eonsequently all
2() errors eaused by retardation of the projeetile may be obv;.ated.
The angle of inelination of the plane defi:ned by the
trlnsduee:rs and the "horizorL'SIllust be such that t~le plane
intersects the trajectory o~ a bullet at a point closer to the
transdllcers than the point of` origin of the ~irst shock wa.ve
that woulcl be detected by the transdueers if the shielcling
nleans were not there.
Figu~e 25 illus-trates the shieldi.ng means .136 and a
transducer 135 and also .illus-tra-tes a l~ullet passing along
a I;rajectory :1.37 gc,~nerating a conlcal .s]Lock wav0 13So Flgu-
25 a:l.so -l.l.l~-L.strates tlle target, 139 at whi(11 the bullet was ~irec1
_ ,'j~ (! ~
- - . ~ : :; , . . .
2~36~æ
- Figurc 2~ illus~rates t]le situction ~f`-tel a ~rief
per;.od o:~ t;.llle ancl sl~ows that t~-e shock ~ra~Te 138 has advarlc~cl,
but has no-t :impinged upon the transducer 135.
~igure 27 illustrates the situatioll a:rter :f-urther brleI
per~ocl of tirn~ and shows tha-t tll~ conica.L shocl~ wave does not
impinge UpOIl th.e transducer 135 since the shi.e.1.d 136 de:~i.nes
a "slladed" area whieh is bounded by the plane 1ll0. Within the
region def.ined by tlie plane lLfo a spherical ~rave 141 is forrned,
this spherical wave impinging upon the tran.sducer ~35 as
illustrated in Figure 28 which illustrates the situation at a
later pOillt in time. :Ct ean be seen that the spherical wave
that actuall-~ impinges on the transducer 135 or:igi.nates ~rom
a point 142 which. is de~i.ned by the shield 136 and -the
transducer 135.
It is to be understood that whilst the plane de:fined by
the transdueers and the shield mav be inclilled it is preferred
for the pl~le to be substantially vertica.l. Th~ls tha "hori~on"
is substc~ntially vert:ieally located above the transclueers an.d
thus the transdueers only deteet the shoek wave or projeeti:Le
gonerated by the projeetlle when the projectile is immediately
above the -transclueers. l`he shielding means 136 ma-y comprise
an elongate eonerete member or a metal strip.
It has been found that tlle overall accuracy o~ a range
i.n~aeeordanee with the presellt invention may be optimised i~
th~ transdueers are arranged i.n a specific array. The
preferr-3d array is illustra-ted ln ~igure 29, and it is to be
no-ted tha-t the array comprises two linear rows o~ transducers `-
142, lL~3, the rows pre~e:rably being parallel 9 a:nd the
transducers being evenly spaeed in the rows9 tht3 transdueers
o:~ ol~e I`OW 11~2 be:ing substantl.a.l.ly co-allgned wltll the
_ s~D -
. . . . ... . ..
. .
- ~ , . .. : ,., :.:
` ....... : ,, ,
:
:: . : .: : . ,, , ,:
, :. , .:. ::
9.~L;28~
-
~ transclucers 143 of` the o-tller ~ow. The two rows may bc in a
si~gl.e horizoll-l,al plane~ or may ~e i.Jl a vertical pl.ane or
may 'be in a pl.~ne at any inclination. Th.e transducers a,re
pre~erably loc~-l.tecl in froJlt of~ the target ].L~ but the row
of transducers ].Ll2 i9 pre~erably substantially in the plane
of -the target 144. Where two rows of tran~sducers arc providecl
as illustrated in Figure 29 each row of transducers may be
provided with a separate shielding means 136 as illustrat,ed
in Eigure 24. In such, an embodiment of the invention the
shock ~ave gensra-ted by a bu]let as it passes -through each
of two pla.nes will be detected by the transducers of the
respective rows of transducers.
Fi.gure 30 illustrates a weapon in accordance with the
invention ~or use w:i.-th a range in accordance with t;he
invention as described above 9 although. the weapon may be
used in other ranges. The weapon comprises a con~entional
rifle 145 7 but it is to be appl~eciatecl that the weapon
may be any other conventional type o~ weapon. The rifle
145 is provided with four pressure sensitive transducers
1~6, 147, 148 and 149, the pressure sensitive transducers
being located at -the parts o~ the ri:~le that are engaged
by t~e trainee marlcsman when the r:;~le is being fired. Thus
there :is a l.ransducer 149 in the ~utt of the rifle 9 that '`
~eing the part of the rifle that is urged against the shouldsr
of the trainee marksmsn. There is another transducer 148
at the cheek of the ri~le, that is to sa.y the part of the
rifle that is engaged by the cheek o~ tne trainee marksman.
Furt,her transducers are pro-vided at the !nain halld grip 147
~nd tl~e fors-hancl grip 146 of -t;he rifle, -the~se being t;he par-t
3~ o:~ the ri:~le actually gr.ipped by the h~nds Or -the trainee
_ 51E -
. / ~; . ;, ~ ' .' ' ' ! ' ' , .'., . . ' i '
gL~2E36~;~
marl;srnall. Tlle pressllre sell.s:itive~ trallsdllcers Illay be
releasal)ly attach~3d to -tl~e rifle, bu~ i.t is pr~f`errod -t~iat
the trans~uc~rs a-l^e int~grally ~orlne~ ~ith the rl~le
so that t~le sur:~aces o:C -the trcmsduce~rs are rlush with the
remaining surraces o* thè r;r:L.e and so tha-t thc rifle has
the same ":~eel" as a rifle not provlded with the transducers.
Th~ ~ransducers 1)~6~ 9 may be of any convenient
type, and thus may comprise a strain-gauge type transducer
~ ich~ as an increasing pressure is applied to the transducer
1.0 cause an increase in strain to be applied to an elongate
w:ire, the resistivi-ty of the wire baing measured and being
indicative o~ the s-train applied to th.e plates, one plate
being smooth and the other plate being provided w.lth
pyramidal projections extending towards the *irst plate,
the plates being separated by a th:in sheet o* rubber or other
such insulating material. As increasing pressure is applied
to the transduce:r -the insulating material will be de~ormecl
by the ~pyramidal projections and the electrical resistance
and/or capacitance batween the two-plates will vary. This
resistance and/or capacitance may be measured electronically
by apply:ing a voltage across the pla-tes and observing the
resuLtant current flow or by applying ~ alternating voltage
to tlle plal;es and measuri.ng the capacitance. In yet a fur-ther
~orm o* t:ransducer may be us~3cl in the presen-t lnvention
pressure may be applied to a body constitu-ted b.y carbon
granules simi.lar to -t:he body present in -the conven-tional carbon
microphone, and thus the res:is,i,ance o:~ the body o* carbon
granules will a.lter in respoIIse to applied presswre. 1'he
resistance of` the bod-y of carbon grc~lwles may be measured
electrolJ.i.c~ll.].yg a.gaill by apply:Lllg a ~roltage and observi.ng or
- ,~j :I J? .......................... !
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LZ86~L2
` measuring t]Ze r~ul-tant current 1 l ow.
In any e~en-i, the rifle :is provided witll the above
described plurality of pressure sensitive tr,lllsducers and
the t:ransduccrs are connected, for example by mei~ns of a
lead 1.50 to a compara-tor 15.1. and thus to a computer l52.
The comparator 15l is provi.ded wi.-th an appropri.ate memory
or means providing reference signals, and the signals
representative of the pressures applied to the various transducers
011 the rifle are compared with si.gnals representative of
predetermined pressures which are deemed to be the correct
preisures. S:ignals are t]lUS produced which indicate
whether the pressure applied to any particular transducer
is correct, i.s too great 9 or is too lit-tle. A display
device 153 is provi.ded and portion of -the display device
provides a dlsplay as illustrated in ~igure 31 ~vhich
illustrates a sc:reen l54 of the display device 153. Shown
on the screen l54 is a ~epresentation l55 o:f the rifle
14$ arld also the screen is provided with four illuminated
indi.cating devices 15~6, 157 9 l55, 159, each display de~ice
corresponding to one of -the transducers. In one mode of
operal;:ion t.he display device 1~3 will cause tl3.e pressures
appl.iecl to the transducers to be displa.yed instantanecusly,
and t1~1.s a tra:inee marksman may grasp -the rifle and may
a~just his grip and firi.ng position until such -time -th.at the . .
di~play con:firms that tbe correct pressure is being app:Lied
to`ieach o:f the transducers. Thus, when the trainee marksman.
il1itially grasps the ri:fle it may be that too great a
pressure is being ap~lied l:o two o-f the transducers, ancl
too small a pressllre is being appl-;ed to the rcmain:ing -I~vo
transducerc;. Th.~s the trail~ee ma.rksmal~ may ini.-tially release
..
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- i !: :, : :: ~, .' . , ~ : . , :,
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the pressl.c l-pl~liecl-to tlle ~irst -two transd~cers until
the correct pressure is indicatcd as bein~ applie~ ancl
subsequen-tly -the trainee l~arl~sm.ln may increase -the pressure
app]ied to ttLe relllaini.ng two -trangclucer~ unt:il agai:n thc
S display ind:;cates that the corr~ct pressure :is being
applied. Thus the trainee marksman may get the feel of
the correct :E:irlllg position and th.e correct appli.ed pressures.
In a second mode of operat:ion o~ the device no pressures
are indicated oll the display device until the trigger is
.~0 pullecl and the round is ~ired and then the display will
indicate the pressures applied to the various pressure
transducers at tlle ins-tant o~ ~irlng o~ the ri:~le. The
displ~y will be maintained on the display device ~or a
predetermined period of time and then the display wlll be
L5 erased to permit he trainee marksman -to proceed to ~ire
anol;her round.
Whils-t there are many ways i.n which the display could
indicate the application o~ the correct pressure or the
incorrect pres~ure, iYl one embodimen-t the display is providecl
with the devices ].56-159 ~or illuminating parts of the
rep.Lrcsentation o~ the rif`le corresponding to the par-ts o~
the riflQ prov;.cled wi.th -the pressure transducers with light
of` di~erent colours, Thus th.e portions ].56-159 the ri~le
may be il].uminated with the red light i~ the pressure applied to
the ri~le is too great~ green li~ht :L~ I;he pressure is correct
~nd with -the yellow light i~ -the pressure -is insuf:Eicient.
7~1ilst the dev:ices 156-159 may each merely comprise three
bulbs oI` di~eren-t colour moun-ted behirld a single lens or
tran~P.~rent WinClOW 1J1 .a display it is to be appreclated t,hat
3~ the displcay ~lay be prov-:i.ded or. a colour cathode ray tube
~ 51~I ~
,,
, . ,~ . ,
~ ' anc] in suc]-l a case -l;ho colour oP the rer)r:esentat:i.on oP any
partlc~lar .~rec.lln-ly g,ra.dua].].~ l~e modulatod :in respollse to
~M :incre~se ln pro~sswre ~ppl:i~d -to the tr~nsclucers.
It is preferred that a sensor i.s provided orl the
trigger adapted to sense whell t:he markslrJcln tak.es the Pirst
pressure on the trigger and this sensor :is connected to a
-timing device to onsul-e that the trainee marksman maintains
first pressure Por an adequate period oP time. IP the
trainee ma.rlcsman snatches the -trigger without holdlng the
:L0 Pirst pressure for a sufPicient period oP time, a lamp 160
may bo illwili.nated on the di,splay.
3l
~igure-~4-also i],lustrates a Pibre optic bundle
161 which is colmected -to 1;he rear sight 162 oP the rifle
145. The Pibre op-tic b~ndle is connected to the rear sight
L5 oP the weapon is such a way that ~hils-t the trainee marksman
may still see over the rear ~;,ight towards the target, an
image corresponding to the image viewed by -the trainee
ma.rlcsman is ~ithcdra~l through the fibre optic bundle 161.
The Pibre optic bundle 161 is collnec-ted to a vidicon tube
20 . ~` or o-ther image recording device 1,62 as .illustrated schematically
in l~igure 33, ancl the output o:E` t,he image recorcling dovice
:is :E`ecl to -the computer 152 where the ,image may be rec~rded
or ~storecl. TI1Q image may also be supplied to a disp't.ay
dbv:ice 163 provided Por -the range con-troller, although the
,~5 di~splay device 163 may be provided adjacent the trainee
marksman. ~t will be appreciated tha-t tlhe person -trai,ning
a trainee ma.rksm~m wi,.l be able to observe precisely the
same image as that observed by t.he trai:nee marksman when
Pi,ri,Mg the woapon, and the vi,clicoM or tube or other device
i.62 may 't~e a-.lapted to recorcl o.r~.ly th.e :ima.ge vi~wed 'hy the
~ 51~ -
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~2~3642
trainee marksman at the instant of firing or to record the
image vi~wed by the trainee marksman all the time.
Since breathing is an important part of accurate
shooting it is preferred to provide the trainee marksman
with means for monitoring his breathing. It is envisaged
that such means may comprise a belt 164 tightly worn by the
trainee marksman, the belt incorporating strain gauges or
the like. As the marksman breathes in, so the strain gauges
may be placed under tension, and thus the breathing of the
trainee marksman can be monitored. Preferably, the belt is
also provided with transducers or the like adapted to detect
the pulse of the trainee marksman, so that the pulse rate of
the trainee marksman can again be monitored. Signals gene-
rated by the strain gauges and the transducers are supplied,
through a lead 164', to the comparator 151 and thus to the
computer 152. The information may be stored or recorded by
the computer 152.
Figure 32 illustrates a marksman utilizing a rifle
145 as illustrated in Figuxe 30 and wearing the belt 1~4,
and it can be seen that the marksman is firing at a target
and is provided with a display device which provides a rep-
resentation of the target indicating where bullets fired at
the target actually impinge upon the target, the display
device also providing a representation of the rifle providing
an indication of the pressures applied to the various partæ
of the rifle by the trainee marksman.
Whilst one particular rifle in accordance with the
present invention has been described it is to be noted that
the means for recording an image corresponding with the image
viewed by the trainee marksman may comprise any appropriate
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-,. ~
means, alld ~ cor~)orate tlle llse o:f` a semi-silverecl
nlirror or other such dcvice. Wl~ l.st the invention has
been clescribecl wil,ll re-L`erence I;o an embodiment in whi.ch
transducers a:re mountecl o:n a ri:~:l.e, -the transducers may
be~ moun-ted ;n gloves worn by a marksman utilising ~lle rifle.
3 L~ 3.5
Figures ~ an~ ~ are flow char-ts Or the two computing
processes described above, with reference to ~igures 4 and 15.
- - 52 -
It ~lill be understood that -those skilled in the
art can readily prepare ~rom these flow charts, and from
the equations developed above, a speeial~purpose computing
and controlling arrangemcn-t for carrying out the
described sequenee of ~uncti.ons~ Those skilled in the
art wi.ll furthcr recognize that one or more general~purpose
computers may be rea~ily programmed to perform such
~unctions without resort to undue e~perimentation. For
this reason~ more detai.led description o~ apparatus ~or
~ these p~rposes is not deemed necessary here7
It is to be nppreciated that in certain embGdinlents
of the invention the transducers may need to be in a
three dimensional array, rather than in a single plane.
In yet ano-ther embodiment of the invent:ion any
errc~s causecl by de-acceleration of the projectile may be
overcome by providi.ng the computer with in~ormation
concerning the law of deceleration or other parameters
n~fecting deceleration o~ the bul.le-t, the computer thus being
able to calculate -the deceleration of` any part-;cular bullet
~n~ to correct ai~ errors caused by such decle:ration.
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