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Патент USA US2408071

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Sept. 24, 1946.
A
_H. |_. HULL ErAL
SYSTEM FOR PosITIoNING 4HEAVY 'OBJECTS
Í Filed June 2o. .1942
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2,408,070
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Sept. 24, 1946.
H, 1_, HULLA ET A_l.
2,408,070 i
SYSTEM -FOR POSITIONING HEAVY OBJECTS
Filed’June 2o, 1942
2 sheets-sheet 2
203
INVENTORS,
HARVARD L. HULL
and
DAVIBDYJ. MUNROE;
_THEIR
ATToRNE .
2,408,070
UNITED STATES PATENT OFFICE
Patented Sept. 24, 1946
2,408,070
SYSTEM FOR POSITIONING HEAVY
e
OBJECTS
Harvard L. Hull, East Williston, and David J.
Munroe, Brooklyn, N. Y., assignors to Sperry
Gyroscope Company, Inc., Brooklyn, N. Y., a
corporation of New York
Application June 20, 1942, Serial No. 447,828
19 Claims.
1
The invention relates to systems for auto
matically positioning guns or other objects pos
sessing substantial inertia in accordance with
positional data supplied from a remote source
(Cl. (iO-_53)
2
referred to applications, which has important ad
vantages in the positioning of heavy objects, such
means comprises a variable speed hydraulic gear
of the type known to the trade as the Vickers
gear wherein a variable displacement pump drives
a hydraulic motor at a speed corresponding to
and has to do with systems of the above type
in which control of the positioning means is
the pump displacement. The operating fluid
exercised by varying the setting of a speed con
used in such a drive is usually an oil of relatively
troller.
low viscosity (particularly at working temper
Systems of the general type above referred to
include the arrangements disclosed in the co 10 atures) which is subjected, in operation, to pres
sures ranging up to several hundred pounds per
pending applications of one of the present in
square inch. Leakage in the pump and motor
ventors, I-I. L. Hull, joint with W. S. Gorrill and
of such a drive increases with increasing oper
W. F. Frost, Serial Nos. 425,146 and 441,400 filed
ating pressure and may be considered to be pro
December 3l, 1941 and May l, 1942, respectively.
portional to pressure, at least to a first approxi
Such systems employ both line and coarse data
mation. Likewise compression of the oil in
channels to supply control signals proportional
creases substantially in proportion to increasing
in dilferent ratio to the errorin following, these
pressure. Because of these two factors the full
signals being selectively utilized to control the
effect of a change of displacement setting of the
positioning means dependent upon the magnitude
20 pump is not at once translated into a change
of the error.
Thus, during normal operation, the íine chan
of operating speed of the hydraulic motor and
the coarse signal acts to reduce the error to a
duced effectiveness ofthe damping signals due
to improper phase relationships, the present in
this lag is substantially proportional to the oper
nel signal exercises control but if the error ex
ating pressure.
ceeds a predetermined amount control is shifted
y To overcome the harmful elîects of lag in the
to the coarse signal by some form of synchro
nizing means. Conversely if the initial error is 25 hydraulic gear on the response of the controlled
object to controlling signals, including the re
beyond the range of control of the fine signal
value within such range, after which the line
signal should promptly assumecontrol. How
ever, certain diñiculties are encountered in syn
vention includes means for obtaining and utiliz
30 ing a corrective term which is proportional to
chronizing from a position greatly dilïerent from
the datum position among which is the tendency
of the controlled object to overshoot not only the
synchronous position but to pass through and
the oil pressure of the hydraulic drive.
One object of the invention, therefore, is to
provide in a positional control system employing
means resulting from sudden starts and stops,`
governing the operation of the controlled object
iine and coarse control channels, means in ad
beyond the entire range of ñne control so that 35 dition to -normal synchronizing means, aiding
the shifting of control from the coarse to the ñne
an oscillation or oscillators of considerable mag
channel.
nitude may occur before the system settles down
Another object is to provide, in a system
to normal operation.
wherein a controlled object is driven in corre
To overcome this undesirable tendency, and
also to prevent undue strain of the positioning 40 spondence with received positional data, means
driving means in accordance with ñne and coarse
measures of the error in following and the rate
of change of each.
Another object is to provide in a positional
trol range and thereby enables the ñne signal to 45
control system employing lboth fine and coarse
take control promptly when the error falls with
control channels, means for obtaining the rates
in this range. During normal operation, a ñne
of change of the error signals in each of said
error rate or damping term is used to prevent
the system disclosed herein makes use of a coarse
error rate term which effects retardation of the
controlled object as it approaches the fine con
channels and utilizing said rates independently
The effectiveness of rate terms in damping 50 to damp the motion of the controlled object over
different ranges of error.
oscillations of the controlled object, and also
Another object is to provide in a positional
other operational characteristics of a positional
hunting about the synchronous position.
control system employing both ñne and coarse
control system, is a function of the time lag or
control channels means within the coarse chan
phase shift of the response of the positioning
means relative to the causitive signal.v Appre 55 nel operative to retard motion of the controlled
object as the ñne control range is approached,
ciable lag occurs in many type of drives due to
thereby
to prevent overshooting said range.
inertia effects, elastic deformation, and other
Another object is to provide, in a control sys
similar factors.
tem employing hydraulic driving means, compen
Considering more particularly the driving
means illustrated in the present and the above 60 sation for factors delaying or modifying the out
2,408,070
3
put response of such means to an input impulse
mitters I2 and I4 at `different rates determined
or signal.
by the ratio of gears I I.
Another object is to provide compensation for
the compressibility of the operating fluid in hyf
stator windings excited from a single source of
alternating current 5 which is preferably a com
mon supply for the entire system in order to
draulic driving means for a controlled object in
a positional control system.
Another object is to provide compensation for
phase displacement in such' hydraulic means be
tween an applied controlling impulse and there
sponse of the driven object thereto.
v
fsecure a uniform phase. Fine transmitter I2,
which is driven at the faster rate and therefore
vgenerates the larger of the two signals for a
given displacement of shaft ID, has its rotor wind
ing connected by three-conductor transmission
Y
A further object is to compensate for variable
leakage in such hydraulic means.>
f
Both transmitters have
»
line I5 to the winding of stator I6 of Selsyn re
ceiver -I1 Which is operated as a synchro trans
Other objects and advantages of this inven
tion will become apparent as the description pro
former o-r signal generator by having its rotor
ceeds.
intermediate gearing 22.
I8 driven from gun 2D by Way of shaft 2l and
It is to be understood that the term “factor”
as employed herein and in the claims is to be
construed as including not only those factors
hereinabove stated for exemplary purposes as
inertia, elasticity, leakage and compression, such
examples being applicable to the hydraulic sys
tern herein illustrated, but also as including other
factors which are detectable or measurable and
which cause lag in the system. Additionally,
elastic deformation of an element, as recited in
the claims, may occur in a hydraulic sense in
the lluid, as an element, as well as in a mechan
ical sense in various parts or elements of the
drive.
In the drawings,
Y
displacement of rotor 29 in one direction or the
other, to either of contacts 32 or 33, theseftwo
contacts being connected in parallel. Receiver
21 has a casing, not shown, of a known type
mounted for rotation and geared to the gun so
that the entire receiver turns with the gun while
the rotor 29 thereof is free to turn with respect
to the casing. This arrangement is shown in the
30 patent to Mittag et al., No. 1,958,245, issued May
8, 1934. The second receiver 35 is likewise con
Fig. 1 is a schematic representation of a sys
tem, according to the invention, for positioning
a gun or other heavy controlled object in ac
cordance with received positional data.
Fig. 2 is a detail, partly in section, of a pres
sure sensitive device suitable for obtaining an
electrical signal.
nected to transmission line 26 and is operated
as a ysynchro transformer by having its rotor 3l
driven from gun 20 by-way of shaft 38 and inter
. mediate gearing 39 to furnish a coarse positional
control signal.
The utilized ñne error signal is derived from
Fig. 3 is a sectional view of a different type
of pressure sensitive device.
Y
Rotor winding 25 of coarse transmitter Irl is
connected by three conductor transmission line
26 to a pair of Selsyn receivers, one of said re
ceivers 21, being operated as a free rotor device.
Receiver 21 has a rotor 29 carrying on its shaft
a, contact 30 which may be closed, upon suitable
'
the alternating potential induced in winding i8
by applying this potential to potential divider re
Fig. V4 is a diagram of an electrical circuit suit 40. sistance 4I) having an adjustable contact 4 I. The
rate of change of the ñne error is obtained by
able >for use with the device of Fig. 3.
applying the voltage of winding I8 to a balanced
Referring now to Fig. 1, the apparatus units
modulator or full-wave rectiñer comprising a pair
shown Within the dashed lines in the upper left
of `bridge type rectiñers 45 and 46 which may each
hand corner are normal elements of a gunfire
director, for example, of the type described in f comprise elements of the dry `disc type. In order
to obtain a phase sensitive device, each half wave
U. S. Patent No. 2,065,303, to E. W. Chafee et al.,
rectifier is supplied with an A. C. bias from the
dated December 22, 1936. These units together
common supply, rectiñer 45 being biased by a,
with the other apparatus of Fig. 1 constitute con
voltage supplied -by way of transformer 41 and
trol means for aiming the gun in one dimension
only, e. g., in azimuth. It is to be understood 50 rectiiier 4E by a voltage from transformer 48.
that,'in addition, a similar grouping'of apparatus,
The joint output of rectiiìers ¿55 and 4B, which
omitted here to simplify the illustration of the
is a reversible polarity continuous voltage, is fil
tered by means such as low pass ñlter 55 to re
invention, will, in practice, be used to govern the
move ripple and applied to an electrical diifer
aiming of the gun in elevation. Also, certain
auxiliary apparatus such as power limiting 55 entiating circuit comprising condenser 55 and
means, manual operating means and hydraulic
,resistance 51 connected in series.
lt is known that in order to effect differentia
limit stops, disclosed in the aforementioned ap
tion, the time constant of such a resistance-ca
plications 425,146 and 441,400, may advanta
geously be employed in connection with the ar
pacity network should be low or, if alternating
rangements of the present invention, reference 60 quantities are considered, the reactance of con
being had to the prior applications for details of
denser 56 should be large in comparison with the
such devices.
The value of gun azimuth angle as computed
value of resistance 51 and under such conditions
the voltage across resistance 51 may be con
by 'the director is represented yby the angular
sidered to be substantially proportional to the.
position of shaft il). Since the shaft I!) corre 65 time rate of change of the output of ñlter 55,.
sponds to the computed gun position data it rep-y
i. e., proportional tothe rate 0fA change of the
fine error signal. The voltage across resistance
resents corresponding positional data. It will be
51 is applied, together with the fine error voltage
appreciatedy however, that instead of being an
taken from resistance 40, as an input to ampliiier
element of a nre control director, shaft I@ may
itself be considered either a controlling object 70 60 in combination with certain other signal volt-v
ages to be described hereinafter.
or a source o_f positional data. On the other hand
The coarse error signal is derived from the
it may be connected to and angularly positioned
alternating potential in winding 31 by Way of
by any other controlling object, for example, a
input transformer 15l and is rectiñed in abal
telescope or other sighting device. Shaft I0
drives the rotors of'ñne- and coarse Selsyn trans 75. anced phase-sensitive` modulator or rectifier 18
2,408,070
6
5
comprising bridge-type rectiñers 79 and 80, re
spectively biased from the common A. C. supply
by voltages introduced through transformers 82
and 83 respectively. The output of rectifier 'i8
as an input to amplifier Bü by way of the series'
circuit combining the several control signals.
As previously stated, the effect of damping sig
nals is reduced by the lag or phase displacement
in the response of the hydraulic motor to adjust
is iiltered in low pass filter 85 to remove ripple
and the D. C. component is applied to a difier
ment of stroke rod IIA, due to leakage and com
entiating circuit comprising condenser 8l and re
pression of the hydraulic pressure fluid. In order
to compensate for this lag or phase displacement,
sistance 88 in series.
Condenser 81 is shunted or
a signal corresponding to changes in the pres
by-passed by a resistance 90. The utilized signal
is the voltage acro-ss resistance 88 which is applied 10 sure of fluid, i. e., changes in the torque of the
motor, is developed and used to modify the control
in series with the previously described signals and
signals in the following manner.
other signals to be described hereinafter as an
The pressure at which operating fluid is sup~
' input to amplifier 6U.
plied by pump | I6 to motor l I9 governs the actu
Amplifier E0 may be of the type described in
applications 425,146 and 441,400 previously re 15 ation of a further signal generating device Ill@
shown more in detail in Fig. 2. In this iigure it
ferred to, comprising a modulator stage including
will be seen that the pressures existing in pipes
tube IGI Which receives an alternating voltage
Ill and IIE are communicated to a pair of op
both as a plate supply and as a grid bias. Tube
posed pistons lill and |52, respectively. by 'way
iol is coupled to a second amplifying stage in
cluding tube IM, the output of which, through 20 of connecting pipes U33 and isili, respectively.
Piston lill i5 displaceable in cylinder |45 by oil
pressure in pipe M3 against the opposition of
spring Itâ while piston |42 is displaceable in cyl
ing a second phase Hi8 supplied from the com
inder §68 by pressure in pipe IM against the
mon A. C. source through a phase-adjusting con
denser Iûli. A distinctive feature of ampliiier til 25 opposition of spring Md. Pistons lili and M2
are mounted on opposite ends of a common piston
is that it supplies a reversible phase A. C. output
rod
|59, which, through4 a pin and slot connection
responsive to either a reversible phase A. C. input
transformer |05, is applied to one of the stator
phases |96 of two-phase induction motor |01 hav
Ië‘ê rotates rocker arm |53 about pivot point Iâd.
or a reversible polarity D. C. input or the two in
Through another pin and slot connection |55 at
combination. This makes it unnecessary to con
vert all of the control signals to one type of 30 its lower end rotation of rocker arm £53 is caused
electrical quantity, alternating or continuous po
tentials being equally eifective in controlling the
ampliiier output.
to translate cylinder block |57, slidable in guides
|59 and |65.
Cylinder block I 5l' has a cylindrical bore ißt in
which pistons |62 and |83 slide. These pistons
Motor IS? drives »shaft I IB on which is mounted
are mounted `on opposite ends of piston rod Iâ/l
crank H2 operatively connected to reciprocate 35 which
has a central lateral extension or arm |65
stroke rod I I4 of the variable displacement pump
carrying at its extremity the magnetically per
or “A” end IIS of a Vickers variable speed hy
meable armature |57 of a pick-oif device |58
which includes a magnetizable core I'Ill cooperat
numeral |2ii. Pump IIS is continuously driven
ing with armature IE?. Resistance to displaca
by motor I | ß and its displacement may be varied 40 ment of the assembly of piston rod i 5d and arma
by changing the angle between the drive shaft
ture |55 is provided by oppositely acting springs
of the pump and the drive shaft of motor IIS,
H2 and |72' which centralize armature IGT rela
which angle is, in turn, determined by the lon~ `
tive to core im. The opposite ends of bore lüii
gitudinal position of stroke rod IIE. A universal , in cylinder block |57 are connected by a restricted
driving connection (not shown) permits tilting
conduit H5 and this conduit and the end por
of the entire pump relative to the motor shaft
tions of the bore are preferably iilled with a vis
under the control of the stroke rod. Pump IIS
cous fluid which is pumped through the conduit
supplies operating iiuid at a rate dependent upon
upon displacement of the pistons. Suitable means
its eii‘ective displacement to the hydraulic motor
for replenishing fluid lost by leakage pa'st the
or “B” end or" the Vickers drive H9, by Way of 50 pistons may be provided. Conduit H5 is adjust
connecting pipes H5 and II‘I, to operate this
ably restricted by means of screw operated needle
motor at a speed substantially proportional tc
valve lll to provide variable opposition to the
the displacement of the pump and therefore pro
transfer of fluid between opposite ends of cylinder
portional to the position of stroke rod I |12. Motor
IBB and thereby a variable time delay in the cen
55
H9, through gearing |22, drives platform |213 on
tralizing of armature |67.
which gun 2i) is mounted.
Core Ill? of pick-off |63 is formed with three
A direct current generator |25 of either the
parallel legs, the central leg being provided with
permanent magnet type or having a suitably eX
. an exciting winding H9 connected to a suitable
cited iield is driven by stroke motor |53? at a speed
A. C. source, while the outer legs mount, respec
proportioned to the rate of change of position of
tively, the coils of output Winding E35, connected
stroke rod IIll. The actual operating speed of
by leads |22, |82’ t0 the input circuit oi ampliiier
generator |25 may be determined by gearing or
t0. Pick-Gif its is of a well known type which
other connecting means, as III, between shaft
is Widely used as a signal pick-off from sensitive
IIB and the generator armature shaft. The con
instruments for translating displacement of a
tinuo-us potential output of generator |25 is ap
member into an alternating electrical potential.
plied to an integrating and combining circuit |725
draulic drive, generally designated by reference
comprising an input potential dividing resistance
|23 having an adjustable contact |29 slidable
thereupon and resistances lëâi and $32 and con
denser ISS connected in series. Resistance |36
is preferably adjustable. The output of integrat
ing circuit |26 is the voltage drop across con
denser |33 and across a portion of resistance |32
determined by the setting of `adjustable contact
|35 thereupon. This output voltage is applied 75
Thus, when armature |51 is centraiized with re
spect to core Ilil, the two Iparts of winding |86)
receive equal alternating potentials by induction
which may be caused to annui one another.
When armature i6? is displaced, however, this
balance is upset and a net alternating voltage
proportional to the displacement exists in wind
ing
|80.
'
,
.
.
5
As alternative means for obtaining any electri
2,408,070
8
shown in Fig, 3 a pair of carbon pile devices |83,
conduit |15 from one end of cylinder |60 to the
other at a rate determined by the adjustment of
needle valve |11. Thus, during extended periods
|84 which are adapted to be actuated in accord
ance with the pressures in pipes l|5 and ||1.
when a constant pressure diiîerence exists be
tween pipes l l 5 andl | |1, no net signal is supplied
Pistons |85 and' |86 of these devices are slidable
by device |68.
in cylinders |81 and |88 respectively. Piston
|85 is integral with a pressure plate |90 which
The damping of the system, as in the arrange
ment of the above-mentioned application Serial
bears on a stack of carbon discs ISI in an in
No. 441,400, is obtained by causing the output of
cal output responsive to the operating pressure
of the variable speed hydraulic drive, there is
sulating housing |93. Electrical contact to one 10 direct current generator |25 (operated in corre
spondence with change of position of stroke rod
end of the stack is made by way of plate |90,
Hd) to be applied to integrating and combining
piston |85, cylinder |81 and output connector läd
circuit |25 which supplies as an output a con
while connection to the other end of the stack is
tinuous potential having components proportional
made by Way of conducting plate |95 and output
connector |96. Similar arrangements in device 15 to the input voltage to circuit |26 and to the
time integral of said voltage, that is, respectively
|84 permit 4change of pressure exerted on piston
proportional to the rate of change of position of
|86 to cause variations of the resistance of car
stroke rod iid and to the position of said rod,
bon pile |92 which may be connected in circuit
the latter component therefore being substan
by leads |93 and |98’.
tially proportional to the rate of change Of dis
The carbon piles |9| and |92 of devices |83
placement of gun 25.
and |84 respectively form variable resistances
The first named component, which is the drop
which may be utilized as elements in a variety
across a portion of resistance |32 determined by
of circuits, one of which is shown in Fig. 4. In
the position of adjustable contact i355, is by its
this circuit, fired resistances 2Q!) and 25| form
with variable resistances |9| and |92 a Wheat 25 nature effective in damping oscillations of stroke
rod | ill and associated members, while the second
stone bridge circuit excited by battery 263 and
component is effective in damping oscillations of
supplying an output potential to a circuit com
the gun. The time constant of the integrating
prising condensers 255 and 206 and resistance 291
circuit comprising resistances |3il and |32 and
in series. Condenser 2535 may be shunted by a
resistance 268 to obtain an output. The poten 30 condenser |33 is adjustable by Varying the Value
of resistance |353.
tial drop across resistance 231 may be applied by
The coarse error signal is obtained in a manner
way of leads |82 and |82’ to the input to ampli
similar to that described in connection with the
?ler 66 as a substitute for the potential applied
fine error signal. Displacement of shaft Ill causes
by this lead in Fig. 2.
a Voltage proportional thereto to be induced in
In order to trace the operation of the described
winding 31 of the coarse synchro transformer or
system, assume that shaft lll experiences a more
signal generator of a phase corresponding to the
or less sudden angular displacement proportional
sense or direction of the displacement. The out
to a change of computed gun azimuth angle.
put of filter 85 supplies a continuous potential
An alternating potential proportional to this dis
proportional to the alternating voltage of Wind
placement is induced in winding lil and a frac
ing 31 and the potential drop across resistance
tion thereof, determined by the setting of contact
88 has components respectively proportional to
lil, is taken from potential dividing resistance as
the applied voltage and the rate of change there
the utilized ñne error signal. At the same time,
of, the first component being derived by way of
there is obtained at the output of filter 55 a con
the path which includes resistance 9U and the
tinuous Voltage likewise proportional to the volt
second of the components being derived by Way
age in winding I8 and, through the operation of
of the path which includes condenser S1. These
the differentiating circuit vcomprising condenser
two components are, respectively, the coarse error
56 and resistance 51, there is obtained across re
signal and the rate of change of signal which are
sistance 51 a continuous potential proportional
to the rate of change of the iine error signal.
50 applied to ampliñer 6|).
During normal operation, the coarse error sig
Under the influence of the fine signal and the
nal is of negligible importance in comparison
rate of change thereof, motor |51 is caused to
with the fine error signal but when a predeter
position pump stroke rod | I4 of the Vickers drive
mined magnitude of error is exceeded, contact
to change the operating speed of hydraulic motor
| |Q of said drive. Owing to the resulting change 55 39 operated by coarse Selsyn receiver 21 is closed
to either of contacts 32 or 3?», depending upon
of displacement of pump ||5 while this pump is
the sense of the error, thus short-circuiting the
being operated at a »constant speed by motor | i8,
a change of operating pressure occurs in con
necting pipes H5 and lil which is transmitted
to pistons lill and M2 (Fig. 2) and causes a dis
outputs of the fine error and fine error rate cir
cuits, control then being exercised by a com
60 bination of the coarse error, coarse error rate,
the damping signals and the hydraulic pressure
placement of piston rod |50 from its central po
signals. In synchronizing the sending and re
sition which, through connecting linkage, causes
ceiving elements of the system, when the value
a translational displacement of cylinder block |51.
of the error causes the coarse channel to be in
Pistons |62 and |33 in cylinder |50 Will initially
follow the motion of cylinder block |51 against 65 control, the control term proportional to the
rate of change of the coarse error opposes the
the differential opposition of springs |12 and |12'
effect of the error signal in proportion to the
thereby displacing armature |61 and inducing
rate of change thereof and thereby slows the
an unbalanced alternating potential in two-part
speed of operation of motor m1 and may reverse
output winding |88 on core |10. This potential is
applied by leads |82 and |82' to the control cir 70 the direction of operation thereof before the syn
chronizing point is reached, thereby slowing hy
cuit which combines the various input signals ap
draulic motor | | 5 to prevent passing through and
plied to ampliñer 6G. After the initial displace
over-shooting the ñne range of control.
ment of armature |51, a. gradual centralization
As soon as the error is within the iine control
occurs under the influence of springs |12, |12’
which is permitted by pumping. of ñuid through 75 range, Contact 3|] is disengaged from Contact 32
2,408,070
9
10
or 33, as the case may be, and the fine error
of change of. disagreement during the occurrence
of disagreement of large magnitude, means oper
signal and its rate immediately become eiîective
ative to control said driving means in accordance
in bringing the gun to the exact synchronizing
with said iine measure during the occurrence of
point. To summarize the effects of the various
control signals which are utilized, normal control 5 disagreement of lesser magnitude, and means
shifting control between said last two means at
is exercised by the line error signal and fine error
a predetermined- value of disagreement.
rate, the latter term tending to prevent hunting
2. In a positional control system, a controlled
within the fine range of control. The damping
object, driving means therefor, a source of varia
signals obtained from circuit H26 are effective in
stabilizing the system and preventing hunting 10 ble positional data, means exercising normal con
trol of said driving means responsive to disagree
of the members thereof and the occurrence of a
ment between the position of said object and data
constant speed lag is prevented since the charge
of said source within a portion of the range of
on condenser |33 leaks ofi during extended inter
said data, including means for suppressing hunt
vals of constant speed operation and no output
is then obtained from circuit |25. The occur 15 ing during normal control, and means operative
during the occurrence of disagreement greater
rence of speed lag in a system in which the driv
than said portion of the range of said data to
ing means is velocity controlled, such as is de
control said driving means in accordance with a
scribed herein, is further discussed in application
combination of quantities including the rate of
Serial No. 441,400.
'I‘he signal obtained in response to change of 20 change of disagreement, to return said object to
the range of normal control without oscillation.
oil pressure of the variable speed hydraulic drive,
by increasing the output of ampliñer ëll when
3. In a positional control system, a controlled
there is a sudden increase in oil pressure in cor
object, driving means therefor, a source of posi
respondence with a demand for a sudden change
tional data, coarse and fine control channels for
of operating speed of motor H9, dies away when 25 said driving means each including means for gen
erating a signal proportional to disagreement be
this pressure remains constant and therefore is
inoperative to change the positional phase at
tween the position of said controlled object and
which gun 2li follows a constant rate of change
the data of said source and for obtaining there
from the rate of change of said signal, said two
of data.
Since amplifier 60 is responsive to both alter 30 signals being proportional in different ratio to
nating and continuous potentials, the modifica
the disagreement, and means for shifting control
tion of the oil pressure signal generator shown
from one of said channels to the other at a criti
cal value of disagreement.
in Fig. 3, which as used in the circuit of Fig. 4
furnishes a continuous potential output across
4. In a positional control system, a controlled
resistance 287, is adapted to provide a signal
object, driving means therefor, a control for said
compensating for lag in the hydraulic transmis
driving means, a source of positional data, means
sion arising from oil compression and oil leakage,
for obtaining a signal proportional to the rate of
particularly during periods of suddenly increased
change of disagreement between the position of
pressure, in a manner generally similar to the
said object and the data of said source and for
use of the alternating output 'of device Hi8. It 40 applying said signal to said control to damp `the
will be apparent that differential compression of
motion of the con-trolled object, and means for
carbon piles I9! and E92, by bringing about a
obtaining and applying to said control a signal
change of the balance of the bridge circuit,
measuring change of a. factor tending to cause a
causes a continuous potential to be applied across
phase displacement between said first signal and
condensers 2115 and 2535 and resistance 2M. By 45 the response oi said object thereto, .thereby to
shunting condenser 205 with resistance 208' the
maintain said response in proper phase relation
ship to effec-t said damping.'
have a component proportional to the supply
5. In a positional control system, a. controlled
voltage while the effect of condenser 28E is to
object, driving means therefor, a source of posi
produce a component substantially proportional 50 tional data, means for obtaining ñne and coarse
to the rate of change of the applied voltage.
signals proportional in different ratio to disagree
Condenser 205 acts mainly as a blocking con
ment between the position of said object and the
voltage across resistance 201 may be caused to
denser so that when the charge on condenser 266
data of said source, means for obtaining a signal
leaks off during periods of constant diiîerential
proportional to the rate of change of disagree
oil pressure no voltage appears across resistance 55 ment, selective means for controlling said driving
20? and the oil pressure term disappears.
means in accordance with said iine signal during
As many changes could be made in the above
construction and many apparently widely diifer
ent embodiments of this invention could be made
without departing from the scope thereof, it is 60
intended thai- all matter contained in the above
description or shown in the accompanying draw
ings shall be interpreted as illustrative and not
the occurrence of disagreements of limited mag
nitude and in accordance with a combination of
said coarse signal and said rate of change signal
during the occurrence of disagreements of greater
magnitude, and means further controlling said
driving means in accordance with the magnitude
of a factor tending to cause a phase displacement
between at least one of said signals and the re
Having described our invention, what we claim 65 sponse of said object thereto.
5. In a positional control system, a controlled
and desire to secure by Letters Patent is:
l. In a positional control system, a controlled
object, driving means therefor, a controlling ob
ject, means furnishing signals corresponding .to
object. driving means therefor, a source of posi
the positional disagreement of said two objects
tional data, means for obtaining line and coarse
measures of the disagreement between the posi 70 and controlling said driving means in accordance
tion of said object and data of said source and
therewith, and means furnishing a measure of a
a measure of the rate of change of said disagree
factor causing a lag in the response of said driv
ment, coarse synchronizing means operative to
ing means to said signals for further controlling
control said driving means in accordance with a
said driving means in accordance therewith to
combination of said coarse measure and said rate 75 compensate for said lag.
in a limiting sense.
2,408,076
ll
12
7. In a positional control system, a controlled
object, driving means therefor, a controlling ob
ject, means furnishing a measure of the positional
disagreement of said two objects and controlling
said driving means in accordance therewith, and
spo-nsive respectively to positional disagreement
means responsive to elastic deformation of an
element of said driving means for further con
trolling said driving means to compensate for a
of said- two objects and to change of the differ»
ential pressure of lthe fluid in said two conduits.
14. In a positional control system comprising
controlling and controlled objects and servo
means causing the controlled object to move in
correspondence with the controlling object in
cluding a variable speed hydraulic transmission.
means Vfor compensating for variable transit .time
phase shift introduced by said deformation be
tween an input to and an output from said driv 10 of impulses through 'said transmission. including
means supplying a controlling impulse to said
ing means.
hydraulic transmission having components re
8. In a positional control system a controlled
spectively proportional to changes of pressure
object, driving means therefor including a hy
of the operating fluid and the rate of said
draulic transmission, a controlling object, means
for controlling said driving means in accordance 15 changes.
l5. In a positional control system, a controlled
with the positional disagreement between said two
'object variable speed hydraulic driving means
objects and means responsive to changes of pres
therefor, a controlling object, means controlling
sure of the operating ñuid in said hydraulic trans
the speed of said driving means in accordance
mission for modifying the control of the control
means to compensate for lag in the hydraulic 20 with the positional disagreement of said two ob
jects, and means for adjusting said speed rc
transmission arising from compression and leak
sponsive to change of pressure of the operating
age of the operating fluid.
fluid of said driving means, including means for
9. In a control system, a controlled object, a
gradually cancelling said adjustment during
hydraulic drive therefor, a displaceable con
periods of constant pressure operation.
troller, means governing the operating speed of
i6. The combination as claimed in claim l5 in
said drive in accordance with the positional dis
which
adjusting means includes a two part
agreement of said object and controller, and
inductive pick-ofi", means actuated by differen
means responsive-to change of pressure of the
tial pressure changes in the operating fluid of
operating fluid of said drive for controlling the
said hydraulic means for relatively displacing
governing means to alter the speed of said drive
to compensate for lag therein, said speed altera
tion disappearing during extended periods of con
stant pressure.
l0. In a control system, a controlled object, a
the parts of said> pick-oil, spring centralizing
means for returning said pick-ori to
neutral
condition and adjustable delay means retarding
the operation of said centralìzing means.
i7. The combination as Vclaimed. in claim l5 in
displaceable controller therefor, means causing 35
'which said adjusting means includes a pair oi
said object to follow displacement of said con
resistance elements connected in a bridge circuit,
troller including a hydraulic driving element and
means for differentially varying the resistance ci'
said elements responsive to pressure changes in
operating fluid of said hydraulic elements for 40 the operating fluid of said hydraulic means and
a condenser-resistance network of predetermined
altering the speed of said driving element yto com»
time constant in the output of said bridge cir
pensate for lag arising from compression and
cuit for obtaining a transient potential responsive
leakage of the operating fluid.
to bridge imbalance.
ll. In a positional control system, controlling
18. A device for obtaining a transient eiectrical
and controlled objects, means effective on the
impulse in response to a change of pressure comH
relative displacements of the objects for fun
prising a pair of members coupled by viscous drag
nishing a measure of the positional diagreement
means, means responsive to change or" pressure
thereof, variable speed hydraulic means operan
for displacing one or" said members, a two part
ed by the controlling object for driving the conpiek-off generating an electrical potential re«
trolled object into positional agreement with the
sponsive to relative displacement of the parts
controlling object, means furnishing an impuise
thereof from a neutral position, means biasing
of adjustable duration upon change of pressure
said parts toward said neutral position, means
of the operating fluid of said hydraulic means,
operatively connecting one part or” said pick-oil'
and means jointly controlled by the ñrst and
with the other of said coupled member-s and
last mentioned means for controlling the speed
means for adjusting the viscous coupling between
of said hydraulic means in accordance with a
said coupled members.
combination of said measured quantity and said
an element hydraulically driven therefrom, and
means responsive to changes of pressure of the
19. In a positional control system, a controlled
object, variable speed hydraulic driving means
l2. The combination as claimed in claim ll in
which the means furnishing an impulse of ad~ 60 therefor, a source of positional data, means for
controlling the speed of said driving means in ac
justable duration comprises a pressure actuated,
impulse.
variable inductance device, means biasing said
device to a neutral condition and a time delay de
vice for retarding the operation of said biasing
means.
cordance with data supplied by said source,
means for transiently controlling said hydraulic
driving means in accordance with changes in the
65 operating speed thereof to damp motion of the
controlled object, and pressure-responsive means
effective on .the initial operation of the hydraulic
driving means for further ran'siently ccntroliing
the speed of said hydraulic driving means in ac»
ing a variable displacement pump, a hydraulic
motor and a pair of conduits connecting said 70 cordance with change of pressure of the operat
ing iluid oi' said hydraulic driving means.
pump and motor to secure a continuous ilow of
HARVARD L. l-IUL ..
operating iiuid therebetween, and means for
DAVID J. MUNROE.
controlling the displacement of said pump re
13. In a positional control system, controlling
and controlled objects, variable speed driving
means for driving the controlled object compris
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