Download Follow-up system

‘May 7, 1946.
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H. A. SATTERLEE
2,399,695
FOLLOW-UP SYSTEM
Filéd‘ Déc. 23, 1940
37 40 394/
24
/
27
INVENTOR
Howard ,4 J0 r‘fer/ee
BY
-
ATTORNEY
Patented May 7, 1946
2,399,695
uurrsn STATES PATENT OFFICE
2,398,895
FOLLOW-UP SYSTEM
' Howard A. Satterlee, Dayton,
Submarine Signal Company,
corporation of Maine
Application December as, 1946, Serial No. 371,331 7
10 Claims. (Cl. 172-239)
The present invention relates to follow-up sys
tems.
Various arrangements have heretofore been
proposed for the purpose of causing a remote ob
24. High frequency by-pass condensers 26 and
21 are also provided between the cathodes and
grids of the tubes 4 and 5, respectively.
The potentiometer 32 is connected across a
ject to take up a predetermined position in re
sponse to the setting of a control indicator to 5 source of alternating current of the same fre
quency as that which supplies the anodes of the
a corresponding position by an operator at a
recti?ers 4 and 5 but of a phase angle lagging
control station. Among the di?lculties which
the potential of anode II by approximately 90“.
arise in such systems arethe dimculties of re
ducing to a minimum the time lag between the 10 Similarly, the potentiometer 33 is connected
across a source of alternating potential of the
setting of the control indicator and the corre
same frequency as that supplying the anode cir
sponding motion of the remote object, the elim
cuits of the tubes but of a phase angle lagging
ination of hunting and the obtaining of su?icient
the potential of anode I! by approximately 90°.
accuracy in the final position of the remote ob
The magnitudes of the two alternating poten
Ject. It is an object of the present invention to
tials thus introduced into the grid circuits of
provide a follow-up system which will provide
the recti?ers are adjusted to be of a very small
accurate and close coupling of the remote ob
ject with the control device, without hunting
- and which moreover will have the desirable
characteristics of simplicity and reliability.
This and other objects of my invention will
best be understood from the following descrip
tion, taken in connection with the accompany
ing drawing which schematically illustrates the
invention.
As indicated in the drawing, the driving mo
tor I which may be geared or otherwise con
‘nected to the remote object is preferably of the
direct current type having a commutator type
value, depending upon the characteristics oi.’ the
gaseous discharge tubes 4 and 5. The maximum
values of these alternating grid potentials may,
20 for example, be of the order of the magnitude of
the maximum negative potential of the critical
grid voltage curve for the tubes in question‘ at
the anodev voltage used. The critical grid'I-volt
age curve is to be understood as the graph'of the
grid-to-cathode voltage which is Just su?lcient
‘to initiate conduction through the tube at each
instant in the positive hali' cycle of the anode
Potential.
‘It will be understood, of course, that the type
armature 2 and a field winding 3 separately ex- 30
of tubes referred to is that in which when con
cited from a source of direct current. Two grid
duction has once been started, it will continue,
controlled recti?ers of the gaseous electron dis
until the anode potential reverses its polarity,
charge type 4 and 5 provide the armature op
the grid having, control only prior to the time
erating current. Anode potential for the two
tubes is provided by a transformer 6 having a 35 conduction commences in any particular posi
tive half cycle 01' anode potential.
primary winding 1 connected to a source of al
The grid circuit of tube 4 may thus be traced
ternating current and two secondary windings 8
from
the grid 20 through the resistor 22 the po
and 9. The secondary winding 8 is connected
tentiometer 32, the upper half of re tor 24,
' by one end to the anode ll of tube 4 and by the
other end through conductors l2 and I 6 to the 40 the biasing battery 25 and the upper half of
resistor l3 to the cathode i4. Similarly, the
armature 2 and from the latter by conductor II
grid circuit of tube 5 may be traced from the
to the cathode l4 of tube 4. The secondary wind
grid 2| through the resistor 23, the potentiome
_ ing 9 is connected by one end to the anode ii
ter 33, the lower half of resistor 24, the biasing
of the tube 5 and by the other end by conductors
25 and the lower half of resistor l3 to
l8 and I‘! to the armature 2 and thence by con 45 battery
cathode It.
ductor it to the cathode i9 or tube 5. The grids
A control potential for the grids of the tubes
20 and 2| of the two tubes are respectively con
is impressed across resistor 24. The circuit for
nected through current-limiting resistors 22 and
producing the grid control voltage which is to
'23 to the movable contacts 28 and 28 of poten
be impressed across resistor 24 will be described
tiometers 32 and 33 and through the potentiome
subsequently.
ters to the extremities 30 and 3| of a center
It is' convenient at the present time to con
tapped resistor 24. The motor armature 2 is
shunted by a center-tapped resistor l3, the
center tap of which is connected through a b
-
sider the operation of the grid controlled recti-,
~ “tier circuit which has so far been described.
ing battery 25 to the center tap of the resistor 55 Considering, ?rst, the tube 4, it will be noted that
the anode circuit of the tube contains a source
9,399,095
2
tinue'rotation. the tube opposite to the one which
was driving the motor will be made active by the
E. M. 1". generated by motor’s motion, tending to
of alternating current and. the armature 2 of
motor I.‘ It will also be noted that the grid cir
cuit of the tube 4'contains four sources of po
tential in series, namely, the alternating poten- -
reverse the motor.
This action amounts to a
form of dynamic braking which rapidly brings the
motor to'a stop.
tial provided by potentiometer 32, the direct po
tential drop across the upper half of resistor
Let ‘us now consider the circuit for producing
the necessary control voltage for the grids of the
24, the direct potential provided by the biasing
battery 25, and the direct potential drop across
recti?ers 4 and 5. This circuit is shown in the
the upper half of resistor 12.
The drop across the resistor 24, as will be de 10 upper portion of the drawing. It is arranged to
impress a potential across the terminals 30 and
' scribed later, is arranged to vary in polarity with
ii of the resistor 24 which has a polarity corre
the desired direction of rotation of the armature
sponding to the direction of the required displace
2. The magnitude or the potential across resistor
ment of the driven object and a magnitude which
24 may be made proportional to the magnitude
may be proportiona1 to the magnitude of the de
of position change required in the driven object.
sired displacement, or may reach a maximum
The potential of the biasing battery 20 is ?xed at
value even for small required displacement of the
a value su?loient to inhibit conduction through
driven object. To this end a handwheel [0 may
either tube when maximum anode voltage is ap
be arranged to drive a pointer 34 which is
plied and the system is at rest. The potential
drop across resistor i3 is occasioned by the cur 20 mounted adjacent to a scale 35 in such a man
ner that by rotating the handwheel the pointer
rent ?owing through it due to the back E. M. F.
may be rotated into a position corresponding to
generated in the motor armature 2 by its rotation.
If, now, it be assumed that the motor I is at ' the desired position of the driven object. ‘ The
handwheel shaft is also connected mechanically
rest and that a potential is impressed across re
sistor 24 of su?icient magnitude and of such a 25 to the rotor or polyphase winding 38 of a self
synchronous motor 31. The motor 31 is also pro
polarity that the point 30 is positive and the point
vided with a single-phase winding 30 which is
3| is negative, the grid 20 will become positive
with respect to its cathode, thereby permitting
anode current to ?ow through the tube 4 and the
armature 2 during the half cycles of anode po
tential or portions thereof in which the anode I I
- is positive with respect to its cathode. The arma
ture 2 being immersed in the continuous mag
connected to a source of alternating current of a
so
netic ?eld provided by the winding 2 will there
fore commence to rotate under the in?uence of
the recti?ed current impulses ?owing through it.
As the armature increases its speed, it will'gen
high frequency. By this I mean a frequency
which is high compared to the 60 cycle frequency
heretofore used, say approximately 1000 to 2000
cycles per second; but I prefer to use a frequency
in the neighborhood of 1500 cycles per second.
The rotor 35 is electrically connected in parallel
with the rotor 39 of a similar self-synchronous
motor 40 having a single-phase stator winding
M. The rotor 39 is mechanically connected to
the driven object. When the rotor 38 is in the
erate a back E. M. F. which is exactly propor
same angular position with respect to its stator
tional to the armature speed and is available for
control of the recti?er grid at all times when no 40 winding 38 as the rotor 38 is with respect to its
stator winding 4|, there will be no voltage in
current flows through the tube. This back E. M. F.
duced in the winding 4|. On the other hand,
being applied across the resistor It, causes a
when the rotor 36 is displaced relative to the rotor
current to ?ow through this resistor which there
32 there will be a voltage induced in the winding
byintroduces a potential into the grid circuit of
4|. The polarity or relative phase of this voltage
45
tube 4 which opposes the potential due to the
depends upon the direction of the displacement
drop across the upper half of resistor 24. when
and the magnitude of the voltage depends upon
the back E. M. F. across the upper half of resistor
i3 reaches a magnitude substantially equal to the ' the magnitude of the displacement.
The winding 4| is connected across a center
potential drop across the upper half or resistor
24, the potential of grid 20 will automatically be 50 tapped resistor 42 whose extremities are con
varied to cause the discharge in each positive halt
nected to the grids of two high vacuum three
tial across resistance 24 be reversed so that the
are connected to the point 41 through ?lters 4|
65 and 48 which are of suitable value to ?lter out
electrode tubes 43 and 44. The cathodes of these
cycle of anode potential to take place at the right
tubes are connected together and to the movable
instant in each cycle to prevent the motor from
contact 45 of a potentiometer resistance 48 whose
increasing or decreasing its speed beyond that
which corresponds to the magnitude of the poten 55 extremities are connected across the same source
of high frequency alternating potential men
tial then existing across resistor 24. The motor
tioned above. The phase of the potential across
speed is thereby accurately controlled. It should
resistance 48 is therefore the same as that across
also be noted that when the polarity of the po
the winding 48. One end of the potentiometer
tential impressed across the resistance 24 is such
resistance 46 is connected to the center tap of
as to make the point 30 positive, the point Si is
resistance 42 and the other‘end is connected to
negative and the grid 2| of tube 5 becomes nega
the common point 41 or the anode circuits of
tive so that when the tube 4 is operating, the
the tubes 43 and 44. The anodes of these tubes
tube 5 remains inactive. Similarly, if the poten
point 3| becomes positive and the point 30 nega
tive, tube I will become active, causing the motor
armature 2 to rotate in the reverse direction. The
tube 4 then remains inactive. -
the‘ recti?ed high frequency alternating com
ponent introduced by the potential drop across
resistance 40. Each ?lter may comprise, for ex
' ample, a resistance and a parallelly connected
If, after the motor has been running in one
direction, it should be desired to stop it, the con 70 condenser as shown. The anode circuit of tube
43 may thus be traced from the anode of the tube
trolling potential across resistor 24 is reduced to
through the ?lter 40 to the terminal 41 through
zero, so that the bias battery 25 is effective to
a portion of resistance 46 to movable contact 45
hold both grids to cut-oft potential. However,
to
the cathode of the tube. Similarly, the anode
should the reduction of the potential on resistor /
24 be sudden and should the motor tend to con 75 circuit of tube 44 may be traced from the anode
9,889,695
of the tube through the ?lter 43 to the terminal
41 through the resistance 43 to the movable con
tact 45 and to the cathode of the tube. Since
the portion of resistance 43, which lies between
the terminal 50 and contact 45, is in series with
_ the grid of each of the tubes 43 and 44,v it pro
vides an alternating bias potential for the grids
of these tubes. This potential is adJusted to be
3
the driven object also rotates the rotor 33 to
which it is
connected. the rotation
being in such a direction as to bring the rotor 33‘
into positional correspondence with the rotor 36
and thereby ag
reducing the voltage in the
winding 4| to
. Thus when the driven object
reaches the desired position, the motor 2 will
stop.
of such a value that anode current flows through
By the use of the above arrangement a tight
both of the tubes even though there is zero volt 10
coupling is obtained between motion of the hand
age induced in the winding 4|. It will be ob
wheel l3 and motion of the driven object so that
served that the voltage induced in this winding
there is substantially no time lag between them.
The maximum voltage impressed across resistor
24 should preferably be substantially equal to the
full-speed back E. M. F. of the motor impressed
by relative displacement between the two rotors
35 and 39 appears across the resistance 42 and
adds or subtracts to the grid voltage of the tubes
43 and 44, depending upon the direction of the
displacement. If the displacement is in one di
across resistor l3. While it is often convenient
to have the motor operate at a speed proportional
rection, the potential drop across resistance 42
to the required displacement of the driven ob
will be out of phase with the bias voltage on one
of the grids but in phase with the bias voltage on 20 ject, this need not always be the case. Where, for
example, a high sensitivity is desired and conse
the other grid. One tube will therefore pass more
quent rapid follow-up action, it may be preferable
current while the current of the other will be re
to arrange the amplifying ‘circuit so that full
control voltage is impressed across resistor 24
even for small displacements between pointer 34
and the driven object.
I have found that the gaseous grid controlled
recti?er circuit described above operates in this
duced. If the relative displacement of the two
rotors 35 and 33' be in the opposite direction, the
effect on the anode currents of the two recti?ers
will, of course, be reversed.
The result of the anode current flow in the
anode circuits of the two tubes 43 and 44 will be
to produce a potential difference across the ter
minals of a center-tapped resistor 5| which is
follow-up vsystem most satisfactorily when the
controlling potential impressed across resistor 24
a substantially pure direct potential without
connected between the two anodes. The ends of 30 is
alternating components. It is necessary, there
the resistor 5| are also connected to the grids of
fore, to provide a suitable ?lter, as above de
two amplifying tubes 52 and 53 which may be
scribed, to remove any alternating components
operated as Class A ampli?ers. The cathodes of
which may otherwise be present. However, when
the tubes 52 and 53 are connected together and
?lters are introduced into a follow-up system
to the movable contact 54 of a potentiometer re
there is likewise inevitably introduced a time de
sistance 55 which is connected across a source of
lay between the motion of the driven object and
direct potential. The negative terminal of the
the motion of the controlling indicator. Where
resistance 55 is connected to the center tap of
sensitivity and rapidity of response of the con
resistance 5|, and the positive terminal of the re
sistance 55 is connected to the center tap of a 40 trolled object to motions of the controlling device
are required, such time lag is, of course, objec
center-tapped resistor 55 Whose extremities are
tionable,
for it causes the system to act as though
connected to the anodes of the tubes 52 and 53,
an elastic coupling member had been introduced
respectively. Any potential appearing across re
between the controlling and the controlled mech
sistance 5| is thus ampli?ed and will appear
across resistance 56 and also across terminals 30
45
anisms.
According to my invention, however,
such elasticity is substantially entirely eliminated and 3| which lie in the grid circuit of the grid
because of the fact that I use a high frequency
controlled gaseous rectifiers 4 and 5.
in the self~synchronous motor circuit for the pro
It will now be evident that when the position
of the driven object corresponds to the position 50 duction of the controlling potentials. Filters for
such high frequencies can readily be constructed
of the pointer 34‘ so that the position of rotor 35
which substantially eliminate the high frequency
with respect to its stator 38 corresponds to the
components from the control voltage output cir
position of rotor 33 with respect to its stator 4|,
cuit and which at the same time have only a
no voltage will be produced across the winding 4|
negligible time constant.
and equal currents will ?ow in the anode circuits
Having now described my invention, I claim:
of tubes 43 and 44. Since these currents are in
1. In a follow-up system for driving an object
opposite directions, there will be no voltage across
into positional agreement with a controlling ob
the resistance 5| and therefore no voltage across
ject, a power motor for said driven object, a grid
the terminals 30 and 3 I. The motor 2 will there
controlled recti?er circuit for supplying power to
fore remain at rest. When, however, the hand
said motor in one direction or the other in re
wheel I0 is rotated to set the pointer 34 into a 60 sponse
to a direct potential which varies in po~
position corresponding to a desired new position
larity
in
accordance with the direction of posi
of the driven object, a voltage, corresponding in
tional disagreement between said objects and
phase to the direction of the position change
means for generating said potential comprising a
which was made, will appear across winding 4| 65 self-synchronous transmitter motor having a sta
and resistance 42, causing the anode currents of
tor winding energized by alternating current of
tubes 43 and 44 to change. A potential differ
a high frequency above approximately 1000 cycles
ence will therefore exist across resistance ‘5|,
per second and a rotor winding adapted to be ro
which will correspond in polarity to the direction
tated by the operator into a position correspond
of the displacement of the pointer 34. This po
70 ing to the desired position of the driven object,
tential will be ampli?ed by the tubes 52 and 53
a self-synchronous receiver motor having rotor
and will appear across the terminals 30 and 3|,
electrically
connected in parallel with that of the
causing either the recti?er 4 or 5 to energize the
transmitter
and mechanically connected to the
motor 2 and to rotate the driven object in the de
driven object and a stator winding adapted to have
sired direction as above described. Rotation of 75 a voltage induced in it upon positional disagree
4
9,899,690
' ment between the two rotors and their respective
stators, said voltage having an instantaneous po- '
the direction of said disagreement and containing
an alternating component oi said hlghirequency,
larity corresponding to the direction of said dis
agreement. rectifying means, means impressing
said induced voltage on said rectifying means, the
latter being adapted to produce a direct potential
having a polarity corresponding to the direction
a ?lter for removing said high irequency compo
nent and means for impressing the resulting recti
?ed and ?ltered voltage upon said grid-controlled
?ltered voltage upon said grid-controlled recti?er
agreement between said objects comprising self
recti?er circuit.
>
4; In a follow-up system ior driving an object
into positional agreement with a controlling ob
, of said disagreement and containing an alternat
ject, means for producing a direct potential vary
, ing component of said high frequency, a ?lter for
removing said high frequency component and 10 ing in polarity and magnitude in accordance with
the direction and magnitude oi positional dis
means for impressing the resulting recti?ed and
synchronous transmitter and receiver system.
circuit.
means exciting the same with alternating current
2. In a iollow-up system for driving an object
into potential agreement with a controlling ob 15 oi a high irequency above approximately 1000
cycles per second, means mechanically connecting
ject, a power motor for said driven object, a grid
said system with said controlling object and said
controlled recti?er circuit for supplying power to
driven object for producing an alternating po
said motor in one direction or the other in re
tential of said high irequency having a magni
sponse to a direct potential which varies in po
larity and magnitude in accordance with the di 20 tude and an instantaneous polarity correspond
ing to the magnitude and direction of said posi~
rection and magnitude of positional disagreement
tional disagreement, rectifying means for said
between said objects and means for generating
high frequency potential adapted to produce a di
said potential comprising a self-synchronous
rect potential having a polarity and a magnitude
transmitter motor having a stator winding ener
gized by alternating current oi a high frequency 25 corresponding to the direction and magnitude oi
said positional disagreement, and having an al
above approximately 1000 cycles per second and a
ternating component of said high frequency, and
rotor winding adapted. to be rotated by the op
a ?lter for removing said high frequency compo
erator into a position corresponding to the de
nent.
sired position of the driven object, a self-syn
5. In a follow-up system for driving an object
chronous receiver motor having a rotor electrically 30
into positional agreement with a controlling ob
connected in parallel with that of the transmitter
ject, means for producing a direct potential vary
and mechanically connected to the driven ob
ing in polarity and magnitude in accordance with
ject and a stator winding adapted to have a volt
the direction and magnitude oi positional dis
age induced in it upon positional disagreement
agreement between said objects comprising self
between the two rotors and their respective sta
synchronous transmitter and receiver system,
tors, said voltage having an instantaneous po
means exciting the same with alternating current
larity and a magnitude corresponding to the di
oi a high frequency above approximately 1000
rection and magnitude of said disagreement, rec
cycles per second, means mechanically connecting
tifying means, means impressing said induced
voltage on said rectifying means, the latter being 40 said system with said controlling object and said
driven object for producing an alternating po
adapted to produce a direct potential having a po
tential oi said high frequency having a magni
larity and magnitude corresponding to said direc
tude and an instantaneous polarity correspond
tion and magnitude of said disagreement and con
taining an alternating component of said high ire
ing to the magnitude and direction of said posi
tional disagreement, rectifying means ior said
quency, a ?lter for removing said high frequency
high frequency potential comprising a pair of
component and means for impressing the result
ing recti?ed and ?ltered voltage upon said grid
oppositely connected vacuum tube recti?ers hav
ing cathode, anode and grid electrodes, a source
controlled recti?er circuit.
3. In a follow-up system for driving an object
of anode potential for said tubes, means connect—
into positional agreement with a controlling ob
ing said tubes in opposite relation to each other,
ject, a. power motor for said driven object, a grid
means impressing a derivative of said high fre
quency potential upon the grids of said tubes in
controlled recti?er circuit for supplying power to
opposite instantaneous polarity, means biassing
said motor in one direction or the other in re
both of said grids with an alternating potential
sponse to a direct potential which varies in po
larity in accordance with the direction oi posi 55 of said high frequency of the same phase as the
potential of said sen-synchronous system excit
tional disagreement between said objects and
means for generating said potential comprising a
ing current and of a magnitude to cause both
self-synchronous transmitter motor having a
tubes normally to pass current, whereby for one
stator winding energized by alternating current
instantaneous polarity oi said produced potential
of a high frequency or approximately 1500 cycles
the currentpassed by one tube will increase and
per second and a rotor winding adapted to be 60 the current passed by the other tube will diminish
rotated by the operator into a position corre
and vice versa for the opposite instantaneous po
sponding to the desired position of the driven
larity of said produced potential, means in the
anode circuit of each tube for separately ?ltering
object, a self-synchronous receiver motor having
rotor electrically connected in parallel with that 05 out the high frequency alternating component,
means opposing the .?ltered recti?ed outputs of
of the transmitter and mechanically connected to
the two tubes, means deriving a resultant poten
the driven object and a stator winding adapted to
tial corresponding to said outputs and means re
have a voltage induced in it upon positional dis
sponsive to said resultant potential ior altering
agreement between the two rotors and their re
the position of said driven object to remove said
spective stators, said voltage having an instanta
positional disagreement.
neous polarity corresponding to the direction of
6. In a follow-up system for driving an object
said disagreement. rectiiying means, means im
into positional agreement with a controlling ob
pressing said induced voltage on said rectifying
ject, means for producing a direct potential vary
means, the latter being adapted to produce a di
rect potential having a polarity corresponding to 75 ing in polarity and magnitude in accordance
2,899,095
with'the direction and magnitude of positional
disagreement between said obiects comprising
self-synchronous transmitter ‘and receiver sys
tem, means exciting the same with alternating
current of a high frequency above approximately
1000 cycles per sec d, means mechanically con
necting said syste
with said controlling object
and said driving object for producing an alter
nating potential oi’v said high frequency having a
5
tube will diminish and vice versa for the opposite
instantaneous polarity’oi' said produced potential,
means in the anode circuit of each tube for
separately ?ltering out the high frequency alter
nating component, means opposing the ?ltered
recti?ed outputs of the two tubes, means deriving
a resultant potential corresponding to said out
puts and means responsive to said resultant po
tential for altering the position of said driven ob
magnitude and an instantaneous polarity corre 10 .iect to remove said positional disagreement.
sponding to the magnitude and direction of said
8. In a follow-up system for driving an object
positional disagreement, rectifying means for said
into
positional agreement with a controlling ob
high frequency potential comprising a pair of op
iect, means for producing a direct potential vary
positely connected vacuum tube recti?ers having
ing in polarity and magnitude in accordance with
cathode” anode and grid electrodes, a source of 15 the direction and magnitude of positional dis~
anode potential for said tubes, means connecting
agreement between said objects comprising self
synchronous transmitter and receiver system,
means exciting the same with alternating current
of a high frequency above approximately 1000
opposite instantaneous polarity, means biassing 20 cycles
per second, means mechanically connect
both of said grids with an alternating potential
ing said system with said controlling object and
of said high frequency of the same phase as the
said driving object for producing an alternating
potential of said self-synchronous system excit
potential
of said high frequency having a mag
ing current and of a magnitude to cause both
said tubes in opposite relation to each other,
means impressing a derivative of said high fre
quency potential upon the grids of said tubes in
tubesv normally to pass current, whereby for one _
instantaneous polarity of said produced poten
tial the current passed by one tube will increase
and the current passed by the other will diminish
and vice versa for the opposite instantaneous po
larity of said produced potential, means in the 30
anode circuit of each tube for separately ?ltering
out the high frequency alternating component,
a resistor connected between the anodes of the
two tubes so that a direct current will ?ow
through said resistor which is the resultant of
the opposed recti?ed and ?ltered outputs of the
two tubes and means responsive to the polarity
and magnitude of the resulting potential drop
nitude and an instantaneous polarity corre
spondlng to the magnitude and direction of said
positional disagreement, rectifying means for said
high frequency potential comprising a pair oi’ op
positely connected vacuum tube recti?ers having
cathode, anode and grid electrodes, means con
necting said tubes in opposite relation to each
other, means impressing a derivative of said high
frequency potential of the same phase as the
potential of said self-synchronous system excit
ing current upon the anodes of said tubes in
the same instantaneous polarity, means biassing
both 01' said grids with an alternating potential
of said high frequency and of instantaneous po
larity and magnitude to cause both tubes nor
across said resistor for altering the position of
mally to pass current, and means impressing a
said driven object to remove said positional dis 40 derivative
of said high frequency potential upon
agreement.
the
grids
of
said tubes in opposite instantaneous
7. In a follow-up system for driving an object
polarity, whereby for one instantaneous polarity
into positional agreement with a controlling ob
01’ said produced potential the current passed by
ject, means for producing a direct potential vary
one tube will increase and the current passed by
ing in polarity and magnitude in accordance with
the
other will diminish‘ and vice versa for the op
the direction and magnitude of positional dis
posite instantaneous polarity of said produced po
agreement between said objects comprising self
tential, means in the anode circuit of each tube
synchronou's transmitter and receiver system,
for
separately ?ltering out the high frequency
means exciting the same with alternating current
alternating
component, a resistor connected be
of a high frequency above approximately 1000
tween the anodes of the two tubes so that a di
cycles per second, means mechanically connecting
rect current will flow through said resistor which
said system with said controlling object and said
is
the resultant of the opposed recti?ed and ?l
driven object for producing an alternating po
tered outputs of the two tubes and means respon
tential of said high frequency having a magnitude
sive to the polarity and magnitude of the re
and an instantaneous polarity corresponding to
sulting potential drop across said resistor for
the magnitude and direction of said positional
altering the position of said driven object to re
disagreement, rectifying means for said high fre
movesaid positional disagreement. quency potential comprising a pair of oppositely
9. In a follow-up system for driving an object
connected vacuum tube recti?ers having cathode,
into positional agreement with a controlling ob
anode and grid electrodes, means connecting said 60 ject, a self-synchronous transmitter and receiver
tubes in opposite relation to each other, means
system, means energizing the same with alter
impressing a derivative of said high frequency
nating current of a high frequency above approxi
potential of the same phase as the potential of
mately 1000 cycles per second, recti?er and ?lter
said self-synchronous system exciting current
means operatively associated with said system for
upon the anodes of said tubes in the same instan
delivering a direct current, said ?lter being
taneous polarity, means biassing both of said
adapted to remove- alternating current compo
grids with an alternating potential of said high
nents having a frequency not substantially less
frequency and of instantaneous polarity and mag
than said high frequency, motor means for driv
nitude to cause both tubes normally to pass cur
ing said object and means-for energizing said
rent, and means impressing a derivative of said 70 motor, said energizing means being adapted to
produced high frequency potential upon the grids
be activated by said direct current, whereby time
of said tubes in opposite instantaneous polarity,
whereby for one instantaneous polarity of said
produced potential the current passed by one tube
will increase and the current passed by the other
lag between operation of said self-synchronous
System and said motor is reduced.
10. In a follow-up system for driving an ob
ject into positional agreement with a controlling
6 '
aaoaeos
object, a sell-synchronous transmitter and re
ceiver system, means energizing ‘the same with‘
alternating current of a high irequeney above
not substantially less than said hiah frequency.
approximately 1000 cycles per second. recti?er
and filter means operatively associated with said
system for delivering a controlling direct cur
rent, said filter being adapted to remove alter
nating current components having a frequency
same, said source having grid control means to
which said controlling direct current is applied,
whereby time lag between operation 01' said self
synchronous system and said motor is reduced.
a motor and a source or rectified alternating cur
rent of relatively low frequency for operatin: the
,
HOWARD A. SA'I'I'ERIEE.