Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to control systems for
missiles and other moving bodies and is partlcularly though not
exclusively concerned wlth a remote control system for a missile
as described in our copendlng Canadian Patent Application No.
904,308 filed June 4, 1964.
In our copending Canadlan patent Appln. 904,308 there
is described a misslle in whlch the nose portlon is rotatably
mounted in bearlngs on the forward end of a cylindrical maln
body portlon of the missile for rotation about the longitudinal
axis of the missile and is provided with a pair of aileron
control surfaces and a pair of elevator control surfaces pivot-
ally mounted on the nose portion, and a remote control system is
employed by means of which an operator at a ground station can
bring the nose portion of the missile to a preselected roll
attitude by appropriate operation of the aileron control sur-
faces and then sub~ect the missile to a lateral steering thrust
by appropriate operation of the elevator control surfaces.
A space-stabilised gyroscope is mounted in the rota-
table nose portion of the missile and in operatlon feeds to a
comparator in the main body portlon of the mlsslle a slgnal the
magnitude of which is representatlve of the roll attitude of the
nose portion. From the ground station a signal is transmitted
which ls representative of a requlred roll attltude for the nose
portion and this latter signal is applied to the comparator
which produces an output signal representatlve of the difference
between this signal and the slgnal from the gyroscope, and in
response to an output signal from the comparator a swltch is
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operated so as to set the alleron control surfaces in an atti-
tude which will cause the nose portion to rotate from its
present roll attitude to the required roll attitude. As the
nose portion approaches the required roll attitude, the two
signals fed to the comparator become equal and then differ from
each other in the opposite sense with the result that the output
signal from the comparator changes sign and causes the swltch to
swltch over and move the aileron control surfaces to a deflected
position causing rotatlon of the nose portion in the opposite
sense. As the aileron control surfaces have no stable zero
position, these surfaces then hunt about their undeflected
positions with the result that the nose portion is held at the
required roll attitude.
It will be appreciated that in bringing the rotatable
nose portion of the missile to the required roll attitude a
situation would from time to time arise in which the nose
portion is required to turn through almost 360. Some means are
desirable which will ensure that the nose portion takes the
shorter path to arrive at the required roll attitude and it is
an obiect of the present invention to provide a control circuit
in the missile by which the nose portlon can be made to take the
shorter path.
According to the present invention, there is provlded
a control circuit comprlslng a dlfference unlt to whlch first
and second input signals are in operatlon applied to produce a
signal representative of the difference between the two input
signals, a logic circuit connected to receive the signal from
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the difference unlt to produce in response to slgnals applled
thereto exceedlng a predetermlned value wlth respect to a datum
an output of a constant value equal to twlce the sald predeter-
mlned value and on the other slde of the datum, an addlng unlt
connected to recelve the slgnal from the loglc clrcult and the
slgnal from the dlfference unlt to produce an output slgnal
representatlve of the algebralc sum of the two slgnals applled
to the addlng unlt and swltch means adapted to swltch to a flrst
condltlon ln response to slgnals from the addlng unlt havlng
values to one slde of sald datum and to swltch to a second
condltlon ln response to slgnals from the addlng unlt havlng
values to the other slde of sald datum.
In the preferred embodlment of the lnventlon, the
loglc clrcult ls responslve to a slgnal applled to lt exceedlng
a predetermlned posltlve value wlth respect to sald datum to
produce an output slgnal of a constant negatlve value equal to
twlce the sald predetermlned posltlve value, and a further loglc
clrcult ls provlded whlch ls responslve to slgnals from the
dlfference unlt exceedlng a predetermlned negatlve value wlth
respect to the datum to produce an output slgnal of a constant
posltive value equal to twlce the predetermlned negatlve value,
the output slgnal from the further loglc clrcult belng applled
to the adding unlt.
One embodlment of the inventlon wlll now be descrlbed
by way of example wlth reference to the accompanylng drawlngs ln
whlch -
Flg. 1 ls a schematlc perspectlve vlew of a mlsslle as
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described in our aforementioned copending Canadian Patent Appli-
cation Ser. no. 904,308,
Fig. 2 is a part sectional side elevation of a forward
portion of the missile shown in Fig. 1,
Fig. 3 is a schematic block diagram of control appara-
tus embodied in the missile shown in Fig. 1, and
Fig. 4 is a block schematic diagram of a control
circuit according to the invention and forming part of the
apparatus shown in Fig. 3.
Referring first to Figs. 1 and 2, a missile 11 compri-
ses a main body portion 12, a nose portion 13 and a tall portion
14. The tall portlon 14 carrles fixed body stabilising fins 15
and is fixedly mounted on the main body portion 12. The nose
portion 13 includes a pair of elevator control surfaces 16 and
17 and a pair of aileron control surfaces 18 and 19. As shown
in Fig. 2, the nose portion 13 is rotatably mounted in bearings
20 on the forward end of the main body portion 12 and houses a
free gyroscope 21 which is arranged to generate an electrical
signal representative of the roll attitude of the nose portion.
The elevator control surfaces 16 and 17 are rotatably
mounted in bearings 22 for rotation about a common lateral axis
and the inner ends of the shafts supporting the control surfaces
16 and 17 are provlded wlth eccentrically mounted pins 23 and 24
whlch engage in a peripheral groove ln the head of a push rod 25
which extends into the nose portion 13 from the body portion 12.
Within the body portlon 12 the push rod 25 is formed with the
diaphragm 26 which serves as an armature cooperating with a pair
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of solenoid colls 27 and 28 energlsed ln a manner herelnafter to
be descrlbed, the arrangement belng such that upon energlsatlon
of the colls 27 and 28 ln one sense the push rod 25 ls moved
forward lnto the nose portlon, actlng on the eccentrlc pins 23
and 24 and servlng to bring the elevator control surfaces 16 and
17 to a deflected posltlon, and upon energlsatlon of the colls
27 and 28 ln the opposlte sense the push rod ls moved to a
retracted posltlon causlng the elevator control surfaces 16 and
17 to move to a deflected posltlon ln the opposlte sense.
The alleron control surfaces 18 and 19 are controlled
by push rod 29 wlthln whlch the push rod 25 ls slldably mounted,
and the push rod 29 ls controlled ln the same manner as the push
rod 25 by the actlon of a palr of solenold colls 30 and 31
actlng on a dlaphragm 32 formed on the push rod 29, wlth the
exceptlon that the eccentrlc plns carrled on the supportlng
shafts of the alleron control surfaces 18 and 19 are so arranged
that the two control surfaces 18 and 19 move ln opposlte sense
to deflected posltlons ln response to elther a forward or rear-
ward movement of the push rod 29.
The colls 27,28 and 30,31 are energlsed under the
control of apparatus 33 housed ln the maln portlon 12 of the
mlsslle and thls wlll now be descrlbed wlth reference to Flg. 3.
The control apparatus 33 comprlses a battery 34, two swltchlng
unlts 35 and 36, a slgnal comparator 37 and slgnal decoders 38
and 39 whlch are fed wlth lncomlng slgnals recelved by a recel-
ver 40. Energlslng current for the solenold colls 27 and 28 ls
supplled by the battery 34 through the swltch 35 whlch ls
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controlled by a signal transmltted from a remote ground control
statlon and detected by the decoder 38. Energlslng current for
the solenold colls 30 and 31 ls supplled by the battery 34
through the switch 36 whlch ls controlled by the output from the
comparator 37 whlch compares the slgnal generated by the gyro-
scope 21 wlth a further slgnal transmltted from the control
statlon and detected by the decoder 39. Fach of the swltches 35
and 36 ls such that ln a flrst condltlon current from the
battery 34 ls fed through the solenold colls ln one sense and ln
a second condltion is fed through the colls in the opposite
sense.
Referring now to Flg. 4, a mark-space slgnal for
controlllng the elevator control surfaces of the mlsslle and
hereinafter referred to as the lateral demand slgnal and a
further mark-space slgnal for controlllng the alleron control
surfaces of the mlsslle and herelnafter referred to as the roll
demand slgnal are received by the recelver 40 and applled to an
lnput termlnal 41, the slgnals belng transmltted from the ground
statlon to the mlsslle by any method well known ln the art for
example, the lateral demand slgnal appearlng as a frequency
modulatlon of a transmltted carrler osclllatlon and the roll
demand slgnal appearlng as an amplltude modulatlon of the
carrier osclllation. The slgnals at the termlnal 41 are fed to
the decoder 38 whlch smooths out the amplltude modulatlon and
reconstitutes the mark-space slgnal from the frequency modula-
tlon, the latter slgnal belng applled to the swltch 35 whlch
controls the solenolds actuatlng the elevator control surfaces.
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The slgnals appearlng at the lnput termlnal 41 are
also applled to the decoder 39 whlch produces from the amplltude
modulatlon a DC output voltage proportlonal to the demanded roll
angle. The DC slgnal from the decoder 39 is applied to a
dlfference unlt 42 to whlch ls also applled the output signal
generated by the gyroscope 21 housed ln the nose portlon of the
mlsslle. The slgnal produced by the gyroscope 21 ls representa-
tlve of the lnstantaneous roll attltude of the nose portlon and
for convenlence lt will be assumed that the gyroscope slgnal
amplltude ls ln unlts wlth 0,3,6,9 and 12 unlts representlng 0,
90, 180, 270 and 360 wlth respect to a flxed datum attltude
and that the slgnal from the decoder 39 ls ln the same unlts.
The dlfference unlt 42 ls such as to produce an output
slgnal the amplltude of whlch ls a measure of the dlfference
between the amplltudes of the slgnals applled to the unlt, and
the output slgnal from the unlt 42 ls fed to flrst and second
loglc clrcults 43 and 44 and to an addlng unlt 45. The flrst
loglc clrcult 43 ls arranged to produce an output slgnal of -12
unlts when an lnput slgnal ls applled thereto of +6 unlts or
more and the second loglc clrcult 44 ls arranged to produce an
output slgnal of +12 unlts when the lnput slgnal thereto ls -6
unlts or of more negatlve value.
The output slgnals from the loglc clrcuits 43 and 44
are applled to the addlng unlt 45 whlch produces an output
slgnal representatlve of the algebralc sum of the amplltude of
the slgnals applled thereto and the output slgnal from the unlt
45 ls applled to the changeover swltch 36 whlch swltches lnto
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one of two conditions in response to a positive slgnal applied
to it and switches to its other condition in response to a
negative signal applied to it, the switch 36 controlling the
operation of the actuating solenoids for the aileron control
surfaces of the mlsslle.
To facilltate the description of the operation of the
circuit lt wlll be assumed that the gyroscope 21 is in a roll
attitude of +90 from a datum attitude and that the signal
therefrom has an amplitude of +3 units. Assuming for the
present that the nose portion is required to be brought to a
roll attitude of less than +270 say +240 from the datum, the
signal from the decoder 39 will be +8 units. The output signal
from the difference unit 42 then becomes +5 units and neither
logic circuit will be operated so that the output of the adding
unit 45 will be +5 units. If it is assumed that positive angles
are measured counterclockwise then the switch 36 is switched on
by the positive signal to a position in which it sets the
aileron control surfaces 18 and 19 in a condition causing
counterclockwise rotation of the nose portion. As the nose
portion 13 reaches the required roll attitude the signal from
the gyroscope 21 becomes +8 units and the output from addlng
unlts 42 and 45 becomes zero. Swltch 36 will then oscillate
about lts main mean posltion, ma~ntalnlng tne nose portlon 13 in
the demanded roll attitude.
If the nose portion 13 is again considered to be at an
attitude of +goo i.e. a roll attitude signal from the gyroscope
of +3 units, and a demanded attitude greater than 270, say 300
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i.e. +10 unlts, is produced by decoder unit 39, then the differ-
ence unit 42 produces an output signal of +7 units and logic
circuit 43 operates to produce an output signal of -12 units.
The latter signal is added to the output of +7 units from the
difference unit 42 and an output signal of -5 units is produced
by adding unit 45, which in turn operates switch 36 causing a
clockwise rotation of the nose portion towards the datum
attitude. As the gyroscope unit 21 reaches the datum its output
signal becomes 0 and the signal from unit 45 has decreased to -2
units, maintaining the clockwise rotation. As the gyroscope 21
crosses the datum, its output signal changes to +12 units. The
difference unit 42 now has an output signal of -2 units and the
logic circuit 43 ceases to produce -12 units, the output of
adding unit 45 therefore remains at -2 unlts and clockwise
rotation is maintained until the nose portion 13 reaches the
demanded attitude of +10 units when the outputs of difference
unit 42 and adding unit 45 become 0.
It will be appreciated that the nose portion 13 has
now rotated a total of +5 units across the datum due to the
operation of the logic circuit, in preference to a rotation of
+7 units in the opposite direction, where the logic circuits not
incorporated.
The operation of logic clrcuit 44 is ldentical and
would occur if the nose portion was say +270 (+9 units) and the
demanded attitude was less than 90 (+3 units). The nose
portion 13 would under these circumstances rotate in a counter
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clockwlse dlrectlon across the datum and take up the demanded
attltude.
A further functlon of the loglc clrcults ls to enable
the nose portlon to malntaln an attltude on or near the datum.
The operatlon of thls functlon can be understood as follows.
Conslder the system wlthout the loglc clrcults and assume a
demanded attltude sllghtly greater than +0 unlts. If a random
dlsturbance occurs such that the nose portlon ls forced across
the datum to an attltude represented by +12 unlts.
~Theoretlcally thls ls the same attltude, but ln practlce a
flnlte dlfference must occur), the output slgnal from dlfference
unlt 42 wlll now change from zero to -12 unlts and wlll cause
swltch 36 to operate produclng a clockwlse rotatlon of the nose
portlon, through an angle of 360, untll the demanded attltude
of 0 ls reached. As the system wlll be sub~ected to random
forces and wlll tend to overshoot the demanded attltude the same
operatlon wlll be repeated resultlng ln a contlnuous splnnlng of
the nose portlon ln a clockwlse dlrectlon. If now the loglc
clrcults are lncorporated and the same condltlons assumed, when
the output from the gyroscope 21 changes to +12 unlts the
dlfference unlt 42 wlll produce -12 unlts and loglc clrcult 44
wlll operate and produce an output slgnal of +12 unlts whlch
glves an output slgnal of +0 units from addlng unit 45, whlch ln
turn operates swltch 36 and causes a counterclockwlse rotatlon
of the nose portlon 13 across the datum to the +0 positlon, when
loglc clrcult 44 ceases to operate, and the nose portlon 13 ls
malntalned at the demanded attltude. The operatlon of loglc
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clrcult 43 occurs had the demanded attitude been +12 unlts and
the nose portion 13 forced to the +0 attitude.
It wlll be seen that contlnuous splnnlng of the nose
portion 13 cannot occur with the logic circuits incorporated
even should the decoder output be greater than +12 units or less
than 0 unlts and that the nose portion 13 can maintain its
attitude on or close to the datum.
Each of the logic circuits 43 and 44 may take the form
of a conventional "Schmldt-Trigger" clrcult arranged to provide
an output of zero for inputs below the trigger level and a
voltage representing plus or minus 360 of roll for lnputs above
the trlgger level. The trlgger level in the present embodiment
is a voltage representing mlnus or plus 180 of roll respec-
tlvely.
