Jan. 23, 1962
G. MOUNTJOY
3,018,367
SPEED CONTROL SYSTEM UTILIZING FREQUENCY
CHANGE FROM mnucnva: PICKUP
Filed May 6, 1959
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Jan. 23, 1962
3,018,367
G. MOUNTJOY
SPEED CONTROL SYSTEM UTILIZING FREQUENCY
CHANGE FROM INDUCTIVE PICKUP
Filed May 6, 1959
2 Sheets-Sheet 2
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United States Patent
3,018,367
Patented Jan. 23, 1962
2
1
FIGURE 1 depicts a section of a roadway utilized in
demonstrating the invention;
3,018,367
SPEED CONTROL SYSTEM UTILIZING FRE
FIGURE 2. is a block diagram of vehicle carried ‘ap
QUENGY CHANGE FROM INDUCTIVE
paratus incorporating the principles of the invention;
PICKUP
FIGURE 3 is a diagram of one of the counting circuits
Garrard Mountjoy, Little Rock, Ark, assignor to Gen
incorporated in the vehicle carried apparatus; and
FIGURES 4, 5, 6, 7, and 8 illustrate voltage wave forms
occurring at designated points in the FIGURE 2 block dia
eral Motors Corporation, Detroit, Micln, a corporation
of Delaware
Filed May 6, 1959, Ser. No. 811,489
15 Claims. (Cl. 246—182)
gram.
10
This invention relates generally to speed control systems
and particularly to speed control systems adapted, although
-
Referring to the drawings, the numeral ll) indicates a
roadway for a vehicle 12. Situated along the roadway
10 is a command speed signal generator 14 that is adapted
to develop a carrier wave keyed or suitably modulated at
not exclusively, for use with motor vehicles.
a frequency corresponding to some desired command
Among the many concerns of any tra?ic control system
is the regulation of vehicle speed. For instance, the na 15 speed, e.g., 60 mph. This frequency can be varied in a
known Way so as to permit the command speed to be
ture of a section of roadway may be such that it is neces
changed for different driving conditions along selected
sary to limit speeds either for purposes of safety or to
sections of the roadway 14). The placement and the num
maintain constant road speeds over certain sections of the
ber of generators will, of course, be determined by the
roadway so as to provide smooth tra?ic ?ow particularly
during rush hours. It can be seen that it is advantageous 20 environment and the type of roadway. The command
speed signal generator 14 is connected to a sending trans
to be able to regulate vehicle speeds over these sections
ducer such as a command speed signal cable 16 embedded
of roadway by external means, i.e., means outside the
in the roadway 10 and arranged parallel to vehicle move
vehicle and from some central station. With such use
ment so that signal energy is transmitted therealong.
of external means, if driving conditions change, due to
weather for example, the speed permitted over these sec 25 This signal energy, in turn, produces in a known manner
a magnetic ?eld above the surface of the roadway 10.
tions of roadway can be accordingly adjusted.
Also situated along the roadway 10 is a control or road
‘Systems have been proposed for accomplishing this ex
speed signal generator 18 so constructed as to develop an
ternal control electronically, but these systems have not
unmodulated carrier wave for delivery to another sending
been always acceptable due to failures in communication
and because complex and costly equipment was required. 30 transducer such as a road speed signal cable 20. As with
the command speed signal cable, the road speed signal
Also, the calibration of electronic controls with respect
cable 26 is aligned with the path of movement of the
to some reference or desired command speed presents
vehicle 12. As can be seen in FIGURE 1, the road speed
problems, especially if the reference is built into the vehicle
signal cable 2d is of a criss-cross con?guration so as to
carried equipment. If built in, deterioration of the elec
afford alternate zones of high and low road speed signal
tronic components from wear, etc. causes the reference to
intensities, the low intensity zones occurring at the cross
change and induce undesired errors into the system.
over points for the cable 20.
With the foregoing in mind, the invention contemplates
Therefore, as will be explained, movement of the vehicle
a vehicle speed control system that relies on an external
12 over the road speed signal cable 20 and the command
source of signal energy for establishing a reference or de
speed signal cable 16 will induce respectively road speed
sired command speed. More particularly, the invention
and command speed signal voltages in vehicle carried ap~
‘seeks to provide a vehicle speed control system that, in
paratus. These signal voltages are then utilized in propor
addition to having the external signal energy for estab
tioning the vehicle road speed to the command speed.
lishing a desired command speed impressed thereon, also
Considering ?rst the road speed network indicated gen
has another external signal source associated therewith
erally at 22 this network, as can be viewed in FIGURE 1,
for determining actual vehicle speed, that compares the
is positioned on the Vehicle 12 so as to be above the road
two signals by means of novel vehicle carried apparatus,
speed signal cable 20 and within the magnetic ?eld thereof.
and that as a result of such comparison controls vehicle
The network 22 then utilizes a receiving transducer, e.g.,
movement.
a road speed signal pickup winding 24 that is so positioned
Speci?cally, the invention seeks to provide the afore
and arranged on the vehicle 12 that as the vehicle 12
mentioned vehicle speed control system with vehicle car
moves along the roadway 10, the winding 24 will have a
ried apparatus that counts generated signal pulses, the
frequency of which corresponds to vehicle speed, and
compares the frequency of these signal pulses with sig
nal pulses of a frequency corresponding to the desired
command speed.
signal voltage induced therein. This signal voltage, which
will hereinafter be referred to as a road speed signal
voltage, is modulated so as to have a frequency corre
sponding to the rate at which the winding 24 passes
through the zones of high and low signal intensity
thereby producing a wave form something like that de
Another related and more speci?c objective of the in~
vention is to utilize in a unique way a step by step counter
that counts peaked wave form pulses corresponding in
frequency to actual vehicle speed for intervals determined
picted in FIGURE 4. The road speed signal voltage
vehicle movement.
will be applied respectively to an ampli?er 28, a differentia
so developed will be transferred through a detector or de
‘by signals corresponding to the desired command speed. 60 modulating circuit 26 and result in the demodulated wave
The output from the counter is then employed to control
from illustrated by FIGURE 5. Next, the signal voltage
The foregoing and other objects and advantages of the
tor 30, and a clipper ampli?er 32. The clipper ampli?er
invention will be apparent from the following description
32 is utilized to remove pulses of one polarity and to
65
and from the accompanying drawings in which:
produce output peaked pulses of constant amplitude cor
3,018,367
3,
responding to the other polarity. These output peaked
pulses, which have the FIGURE 6 wave form and corre
world in frequency to road speed, are delivered to count
ing circuits 34 and 36.
The command speed network shown generally at 38 is
positioned on the vehicle 12 so as to be adjacent the com
4
to the positive side. In this instance, battery voltage is
applied to the negative side of the counting capacitor
50 whereas this same battery voltage is continuously
applied to the positive side of the counting capacitor 50.
As a result, the counting capacitor 50 will not accept a
charge and the counting cannot recommence until the
command speed signal voltage is again off.
mand speed signal cable 16 and, as with the road speed
As will become more apparent in the operational sum
network 22, includes a receiving transducer in the form of
mary, this counting arrangement can be changed con
a pickup winding 40. It is preferred that signal energy
from the command speed signal cable 16 induce in the 10 siderably to meet the requirements of a particular appli
cation. In this embodiment, two counting circuits 34
winding 40 a signal voltage of the FIGURE 7 wave form.
and 36 are employed and since the command signal volt—
Then after applying this signal voltage to a detector or de
age to one is 180° out of phase relative to the other,
modulating circuit 42, the square wave form pulses dem
more pulses from the resultant continuity are produced,
onstrated in FIGURE 8 will be produced. This so
ealled command speed signal voltage may be increased 15 and accordingly a stronger output. Some applications
may only require one such counter if the output is ade
by an ampli?er 44 before being impressed on counting
quate.
circuit 34. At this point an ampli?er inverter 46 is em
ployed so that the command speed signal voltage delivered
to the counting circuit 36 will be out of phase, prefer
ably l80° out of phase for reasons that will become ap
parent, with respect to the signal voltage delivered to the
counting circuit 34.
Because two counting circuits are employed, a sum
ming circuit 60 is employed so as to sum the outputs
from each. This summed output voltage may be utilized
directly or as in the present embodiment delivered to an
integrator 62 or an equivalent, so as to produce an
equivalent DC. voltage that is further increased by an
Both of the counting circuits 34 and 36 are in this
ampli?er 64 and then applied to a throttle servo 66.
embodiment of the FIGURE 3 type and each comprises
a coupling capacitor 48, a counting capacitor 50, and two 25 The ampli?ed DC. voltage will cause the throttle servo
diodes 52 and 54 all arranged as depicted.
For ex
planatory purposes and without limitation, plus and
66 in an appropriate way to alter the throttle setting so
that road speed will approximate if desired or be in some
predetermined proportion to the selected command speed
of 60 m.p.h.
scribing the circuit. The peaked wave form pulses, in
this example negative, when applied to the coupling ca 30 In summarizing, the operation of the control system
will be so described as to cover two possible conditions.
pacitor 48 will develop a negative going voltage across
minus signs have been assigned as denoted to aid in de
the counting capacitor 50, this being permitted by the
In one of these it will be assumed that road speeds in
excess of the desired command speed are the only con
cern. The other condition assumes that road speeds both
pling capacitor 48 will discharge through bypass diode 54
and the charge on the counting capacitor 50 will nor_ 35 in excess and less than command speed are to be con
orientation of diode 52.
Between each pulse the cou
mally be maintained by the blocking action of the diode
sidered.
Taking ?rst the condition where only excess road
speeds are to be considered and referring to the FIG
URE 3 counting circuit, it will be assumed then that if
counting capacitor 50. As is well known, this buildup 40 road speed and command speed are equal, the corre
sponding frequencies of the peaked wave form pulses and
of potential can increase until the circuit becomes insen‘
the square wave form pulses will also be equal. Con
sitive to any further increase. However, in this embodi
sequently, the FIGURE 3 counting circuit will be so
ment, a semiconductor as transistor 56 either of an NPN
calibrated when road speed and command speed are
or the PNP type depicted is arranged so as to have ap
plied thereto the net potential across the counting capac 45 equal that the counting capacitor 50 will only receive
one charge during the interval the command signal is off
itor 50. Also, an electronic switching action afforded by
and this one count or single charge will be completely
the command speed signal voltage causes the counting
erased and the counting circuit reset before any net volt
capacitor 50 to be reset after erasing part or all of the
age across the counting capacitor 50 can be developed.
charge on capacitor 50 thereby enabling the circuit to
recommence counting.
50 Therefore, the status of transistor 56 will remain un
altered. If, now, the road speed commences to exceed
To accomplish the switching action, the command
the command speed, more than one of the peaked wave
‘speed network 38 is connected through a blocking diode
form pulses will occur during the interval that the com
58 to the negative side of the counting capacitor 507
52. Hence, each successive pulse will cause the charges
on the capacitor 50 to build up in exponential steps and
to produce a corresponding stepped potential across the
mand speed signal voltage is off. For this reason, the
When the counting capacitor is being charged in the just
described manner, the command speed signal voltage is 55 counting circuits 34 and 36 will be further calibrated
off, i.e., the command speed signal voltage is along the
so that all of this charge cannot be removed in the time
interval permitted and a net voltage developed across
FIGURE 8 zero potential line appearing between the
the counting capacitor 50 will change the output of the
square wave form signals. The charge on the counting
transistor 56.
capacitor 50 then will be entirely or partially erased as
the charge is bled off through the blocking diode 58 to 60 It will be assumed here that the throttle servo 66 when
under the in?uence of this automatic control, will be
some area of lower potential as ground. If all of this
maintained in an appropriate way by the command speed
charge can be bled off during the interval that the com
mand speed signal voltage is off, the status of the tran
signal voltage in a setting that will produce the desired
command speed. When the road speed is equivalent to
sistor 56 will not be altered because the net voltage ap
plied thereto will not be changed. But, if the charge on 65 command speed, there can be either no output or some
the counting capacitor 50 is not entirely removed, during
selected output from the counting circuits 34 and 36 and
this will be determined by the bias on the transistors 56.
to the transistor 56 and thereby change the operating
If there is an output, it will have to be correlated with
status thereof.
the command speed signal voltage so as to maintain the
Continuing withthe explanation of the counting cir 70 throttle servo 66 in the command speed setting. Whether
cuits 34 and 36, when the command speed signal voltage
or not there is an output when road speed and command
speed are equal, there will be an output from the count
is on, i.e., a square wave form pulse is received, the
switching action occurs and the counting capacitor 50 is
ing circuits 34 and 36 when road speed exceeds com
reset. This can be produced by applying the same volt
mand speed such that, after being summed by the sum
age to the negative side of the capacitor 50 as is applied 75 ing circuit 60 and processed by the integrator 62 and the
this golf interval, of course, a net voltage will be applied
3,018,367
6
ampli?er 64, the ampli?ed equivalent DC voltage will
cause the throttle servo 66 to reduce the throttle open
ing until vehicle speed again approximates command
speed.
Assuming that the other operating condition is to be
covered by the system, namely, that when under auto
matic control, road speeds both above and below the
command speed are to be considered, this can be accom—
duce an output voltage corresponding to the difference in
the frequencies of the signal pulses, and control means re
sponsive to the output voltage and adapted to control ve
hicle movement thereby causing the vehicle road speed to
be in some predetermined proportion to command speed.
3. In combination with a vehicle, a command signal
generator developing a command speed signal voltage
having a frequency corresponding to a desired speed, the
frequency of the command speed signal voltage being
plished by altering the basic system in different ways as
will be understood by those versed in the art. One way 10 selectively variable remotely of the vehicle, a vehicle road
speed generator developing a vehicle road speed signal
of accomplishing this would be to have the throttle
voltage having a frequency corresponding to actual road
servo 66 adjusted so as to approximate the throttle open‘
speed of the vehicle, the command signal and road speed
ing at command speed. As before, this setting could be
generators being positioned also remotely of the vehicle,
maintained by the command speed signal voltage; then
means producing pulses of a frequency corresponding to
the counting circuits 34 and 36 could be so calibrated
the frequency of the vehicle road speed signal voltage,
that when road speed and command speed were equal,
means for counting the pulses at time intervals controlled
the outputs therefrom would not alter the setting of the
by the command speed signal voltage and developing a
throttle servo 66. But, if the outputs from the counting
corresponding output voltage, and control means respon
circuits 34 and 36 were less or greater than this output
occurring with equal road and command speed output 20 sive to the output voltage and adapted so as to control
vehicle movement thereby causing the vehicle road speed
so as to re?ect respectively a road speed lower than com
to be in some predetermined proportion to the command
mand speed and a road speed greater than command
speed.
speed. the setting of the throttle servo 66 would accord~
ingly be adjusted.
4. In combination with a vehicle, a command signal
Because various applications of the system may have 25 generator developing a command speed signal voltage
having a frequency corresponding to a desired speed, a
different requirements, it has been mentioned that only
vehicle road speed generator developing a vehicle road
one counting circuit may be necessary. This also is true of
“the other circuits shown especially the ampli?ers, for
speed signal voltage having a frequency corresponding to
actual road speed of the vehicle, the command signal and
fewer may be needed than are demonstrated.
It is possible that for some reason, the command speed 30 road speed generators being positioned also remotely of
signal may be lost. Asa result, the driver could be going
the vehicle, means producing peaked Wave form pulses of
very much in excess of the command speed and be un
a constant amplitude and of a frequency corresponding to
aware that his automatic control has been rendered in
effective by the loss of the command s eed signal. There
fore, it is desirable to cause interruption of the automatic
the frequency of the vehicle road speed signal voltage,
control and permit the driver to reinstate manual control.
To do this, a stop relay denoted generally at 68 is in
stalled in the system and arranged so that upon loss of the
means producing square wave form pulses of a frequency
corresponding to the frequency of the command signal
voltage, counting means determining the difference be
tween the actual proportion of the frequency of the peaked
wave form pulses to the frequency of the square wave form
pulses and a predetermined proportion and developing a
rendered inoperative as by biasing one of the stages there 4-0 corresponding output voltage, and control means respon
sive to the output voltage and adapted to control vehicle
of beyond cutoff. As a result, supply of DC. voltage to
command speed signal voltage, the ampli?er 64 will be
the throttle servo 66 will be interrupted and the throttle
movement so that vehicle road speed is in some prede
servo 66 can be so designed as to close the throttle under
termined proportion to command speed.
these conditions.
'. The invention is to be limited only by the following
claims.
I claim:
generator developing a command speed signal voltage
having a frequency corresponding to desired speed, the
. "1. In combination with a vehicle, a command signal
selectively variable remotely of the vehicle, a vehicle road
5. In combination with a vehicle, a command signal
frequency of the command speed signal voltage being
speed generator developing a vehicle road speed signal
having a frequency corresponding to a desired speed, the 50 voltage having a frequency corresponding to actual road
speed of the vehicle, the command signal and road speed
frequency of the command speed signal voltage being
generators being positioned also remotely of the vehicle,
selectively variable remotely of the vehicle, a vehicle road
means producing pulses of a frequency corresponding to
speed generator developing a vehicle road speed signal
the frequency of the vehicle road speed signal voltage,
vvoltage having a frequency corresponding to the actual
road speed of the vehicle, the command signal and road 55 means for counting the pulses at time intervals controlled
by the command speed signal voltage and developing a cor
speed generators being positioned also remotely of the
responding output voltage, control means responsive to the
vehicle, counting means for correlating the frequencies of
generator developing a command speed signal voltage
the signal voltages so as to produce an output voltage cor
responding to the difference in the frequencies of the signal
voltages, and means responsive to the output voltage and
adapted to cause vehicle road speed to be controlled in
accordance with the output voltage.
2. In combination with a vehicle, a command signal
output voltage and adapted so as to control vehicle move
ment thereby causing the vehicle road speed to be in some
predetermined proportion to the command speed, and stop
means for halting the operation of the control means when
the command speed signal voltage is interrupted.
6. In combination with a vehicle, a command signal
generator developing a command speed signal voltage
generator developing a command speed signal voltage hav
ing a frequency corresponding to desired road speed, the 65 having a frequency corresponding to desired speed, a
vehicle road speed generator developing a vehicle road
frequency of the command speed signal voltage being se
speed signal voltage having a frequency corresponding to
lectively variable remotely of the vehicle, a vehicle speed
actual road speed of the vehicle, the command signal and
generator developing a vehicle road speed signal voltage
road speed generators being positioned remotely of the
having a frequency corresponding to the actual road speed
of the vehicle, the command signal and road speed gener 70 vehicle, means producing peaked Wave form pulses of a
constant amplitude and of a frequency corresponding to
ators being positioned also remotely of the vehicle, means
the frequency of the vehicle road speed signal voltage,
developing signal pulses corresponding in frequency, re
means producing square wave form pulses of a frequency
spectively, to the frequencies of the command speed and
corresponding to the frequency of the command speed sig
vehicle road speed signal voltages, counting means cor
relating the frequencies of the signal pulses so as to pro 75 nal voltage, counting means determining the difference in
8,018,367
8
frequency between the vehicle road speed and command
speed pulses and developing a corresponding output volt
nal generator developing an unmodulat'ed carrier wave, a
control signal sending transducer connected with the con
age, means for developing a D.C. voltage representative of
the output voltage, and throttle means responsive to the
D. C. voltage and adapted to alter throttle settings so that
vehicle road speed is caused to be in some predetermined
trol signal generator and providing alternate zones of high
and low control signal intensity along the roadway, a con
trol signal receiving transducer carried by the vehicle and
proportion to command speed.
modulated in amplitude at a frequency corresponding to
the rate at which the control signal receiving transducer
passes through the zones of high and low signal intensity,
a command signal receiving transducer carried by the ve
7. A speed control system for a vehicle adapted to travel
a roadway, the system comprising a command signal
generator developing a carrier wave modulated in ampli
tude at a frequency corresponding to a desired command
speed, a command signal sending transducer connected
with the generator and ?xed relative to the roadway for
transmitting the signal energy therealong, a control signal
arranged so as to have a signal voltage induced therein
hicle and arranged so as to have a signal voltage induced
therein of a modulated frequency corresponding to that
of the carrier wave from the command signal generator, a
detector circuit demodulating the control signal voltage,
generator developing an unmodulated carrier wave, a con
circuit means producing peaked wave form pulses of a
trol signal sending transducer connected with the control
signal generator and providing alternate zones of high
and low control signal intensity along the roadway, a
control signal receiving transducer carried by the vehicle
frequency corresponding to the demodulated control sig
and arranged so as to have a signal voltage induced there
in modulated in amplitude at a frequency corresponding to
the rate at which the control signal receiving transducer
passes through the zones of high and low signal intensity, a
command signal receiving transducer carried by the vehicle
and arranged so as to have a signal voltage induced there
in of a modulated frequency corresponding to that of the
carrier wave from the command signal generator, means
producing pulses of a frequency corresponding to the fre
quency of the control signal voltage, means counting the
pulses at time intervals controlled by the command sig
nal voltage and developing a corresponding output voltage,
and control means responsive to the output voltage and
adapted to control vehicle movement so that vehicle speed
is caused to be in some predetermined proportion to the
nal voltage, a detector circuit demodulating the command
signal voltage and circuit means producing square wave
form pulses of a frequency corresponding to the frequency
of the demodulated command frequency voltage, a count
ing circuit arranged so as to count the peaked wave form
pulses for intervals determined by the frequency of the
square wave form pulses so that an output voltage cor
responding to the difference between vehicle speed and
command speed is produced, means for developing a D.C.
voltage representative of the output voltage, and control
means operated by the D.C. voltage and adapted to control
vehicle movement in accordance therewith so as to cause‘
the vehicle speed to be in some predetermined proportion
to the desired command speed.
10. A speed control system for a vehicle adapted to
travel a roadway, the system comprising a command signal
generator developing a carrier wave modulated in ampli
tude at a frequency corresponding to a desired command
speed, a command signal sending transducer connected
with the command signal generator and ?xed relative to
the roadway for transmitting the signal energy there
a roadway, the system comprising a command signal
along, a control signal generator developing an unmodu
generator developing a carrier Wave modulated in ampli
lated carrier Wave, a control signal sending transducer
tude at a frequency corresponding to a desired command
speed, a command signal sending transducer connected 40 connected with a control signal generator and providing
alternate zones of high and low control signal intensity
with the generator and ?xed relative to the roadway for
along the roadway, a control signal receiving transducer
transmitting the signal energy therealong, a control sig
desired command speed.
8. A speed control system for a vehicle adapted to travel
nal generator developing an unmodulated carrier wave, a
carried by the vehicle and arranged so as to have a signal
voltage induced therein modulated in amplitude at a fre
control signal sending transducer connected with the con
trol signal generator and providing alternate zones of 45 quency corresponding to the rate at which the control
signal receiving transducer passes through the zones of
high and low control signal intensity along the roadway, a
high and low signal intensity, a command signal receiving
control signal receiving transducer carried by the vehicle
and arranged so as to have a signal voltage induced there
transducer carried by the vehicle and arranged so as to
have a signal voltage induced therein of a modulated fre
in modulated in amplitude at a frequency corresponding
to the rate at which the control signal receiving transducer 50 quency corresponding to that of the carrier wave from the
command signal generator, a network for producing count
passes through the zones of high and low signal intensity,
able pulses of a frequency corresponding to the frequency
a command signal receiving transducer carried by the vehi
of the control signal voltage, a step by step counting cir
cle and arranged so as to have a signal voltage induced
cuit connected to the network and arranged so as to count
therein of a modulated frequency corresponding to that of
the carrier wave from the command signal generator, 55 the pulses for a counting interval thereby generating a
stepped output voltage, reset means controlled by the fre
means producing peaked wave form pulses of a frequency
quency of the command signal voltage, the reset means
corresponding to the frequency of the control signal volt
being operative to establish the counting interval for the
age, means producing square wave form pulses of a fre
counting circuit and reset the counting circuit upon the
quency corresponding to the frequency of the command
signal voltage, a counting circuit arranged so as to count 60 completion of the counting interval, and vehicle control
means responsive to the output voltage from the counting
the peaked wave form pulses for intervals determined by
circuit and adapted to control vehicle movement so that
the frequency of the square wave form pulses and thereby
vehicle speed is caused to be in some predetermined pro
produce an output voltage corresponding to the difference
portion to the desired command speed.
between vehicle speed and command speed, and control
11. A speed control system for a vehicle adapted to
means operated by the output voltage and adapted to con 65
travel a roadway, the system comprising a command signal
trol vehicle movement in accordance with the output volt
generator developing a carrier wave modulated in ampli
age so as to cause the vehicle speed to be in some prede
tude at a frequency corresponding to a desired command
termined proportion to the desired command speed.
speed, a command signal sending transducer connected
9. A speed control system for a vehicle adapted to travel
a roadway, the system comprising a command signal 70 with the command signal generator and ?xed relative to
the roadway for transmitting the signal energy there
generator developing a carrier wave modulated in ampli
along, a control signal generator developing an unmodu
tude at a frequency corresponding to a desired command
lated carrier wave, a control signal developing an unmodu
speed, a command signal sending transducer connected
lated carrier wave, a control signal sending transducer
with the generator and ?xed relative to the roadway for
transmitting the signal energy therealong, a control sig 75 connected with the control signal generator and providing
3,018,307
9,
10
alternate zones of high and low control signal intensity
along the roadway, a vehicle speed network including a
control signal receiving transducer carried by the vehicle
ampli?er inverter circuit and to the other counting circuit
being taken from the other side of the ampli?er inverter
and arranged so as to have a signal voltage induced there
in modulated in amplitude at a frequency corresponding
to the rate at which the control signal receiving transducer
circuit so that the square wave form pulses from the
opposite sides of the ampli?er inverter circuit are out of
phase a predetermined amount, the counting circuits being
arranged so as to count the peaked wave form pulses for
intervals determined by the frequency of the square wave
form pulses so that each counting circuit produces an out
tiator circuits successively arranged so as to develop
put voltage corresponding to the difference between
peaked waveform pulses of a frequency corresponding to
the frequency of the control signal voltage, a command 10 vehicle speed and the desired command speed, a summing
circuit for combining the counting circuit output voltages
speed network including a command signal receiving trans
passes through the zones, detector, ampli?er, and differen
ducer carried by the vehicle so as to have a signal voltage
induced therein of a frequency corresponding to that of
the carrier wave from the command signal generator, de‘
so ‘as to produce a summed voltage, means communicat.
ing with the summing circuit so as to develop a D.C.
voltage corresponding to the summed voltage, a throttle
tector, ampli?er, and ampli?er inverter circuits succes
actuating servo operated by the D.C. voltage and adapted
sively arranged so as to develop square wave form pulses
of a frequency corresponding to the frequency of the com
to alter throttle settings in accordance therewith so as to
mand signal voltage, step-by-step counting circuits each
cause the vehicle speed to be in some predetermined pro
portion to the desired command speed, and stop means for
being connected both to the vehicle speed network and
halting the operation of the throttle actuating servo when
the command speed network so as to have the peaked wave 20 the command signal voltage is interrupted.
13. In a device of the character described, the com
form pulses and the square wave form pulses applied re
bination of a roadway having associated therewith plural
spectively thereto, the square wave form pulses to one
sources of signal energy including a source of command
counting circuit being taken from one side of the ampli?er
inverter circuit and to the other counting circuit being
taken from the other side of the ampli?er inverter cir
speed signal energy and a source of road speed signal
energy, the plural sources being so arranged relative to
cuit so that the square Wave form pulses from the oppo
the roadway as to cause the signal energy to emanate
site sides of the ampli?er inverter circuit are out of phase
a predetermined amount, the counting circuits being ar
ranged so as to count the peaked wave form pulses for
intervals determined by the frequency of the square wave
form pulses so that each counting circuit produces an
output voltage corresponding to the difference between ve
from the roadway, a vehicle carried command speed
pickup means and a vehicle carried road speed pickup
hicle speed and the desired command speed, a summing
circuit for combining the counting circuit output voltages
means respectively responsive to the signal energy from
the command speed and the road speed signal energy
sources so as to provide both a command speed signal
having a frequency corresponding to desired speed and a
vehicle road speed signal having a frequency correspond
ing to actual vehicle road speed, counting means cor
so as to produce a summed voltage, means communicating 35 relating the frequencies of the signals so as to produce
an output signal corresponding to the difference in fre
with the summing circuit so as to develop a D.C. voltage
quency of the command speed and road speed signals,
corresponding to the summed voltage, and control means
and means responsive to the output voltage and adapted
operated by the D.C. voltage and adapted to control ve
to cause vehicle road speed to be controlled in accord
hicle movement in accordance therewith so as to cause the
vehicle speed to be in some predetermined proportion to 40 ance with the output signal.
14. In a device of the character described, the com
the desired command speed.
bination of a roadway having associated therewith plural
12. A speed control system for a vehicle adapted to
sources of signal energy, the plural sources being so ar
travel .a roadway, the system comprising a command sig
ranged relative to the roadway as to cause the signal
nal generator developing a carrier wave modulated in
amplitude at a frequency corresponding to a desired com 45 energy to emanate from the roadway, one of the sources
being selectively variable so as to provide a desired com
mand speed, a command signal sending transducer con
mand speed signal, another of the sources affording a
nected with the generator and ?xed relative to the road
road speed signal, a vehicle carried command speed and
way for transmitting the signal energy therealong, a con
road speed pickup means each responsive to the signal en
trol signal generator developing an unmodulated carrier
wave, a control signal developing an unmodulated carrier 50 ergy from its associated source so as to provide respec
tively a command speed signal having a frequency cor
wave, a control signal sending transducer connected with
responding to desired speed and a vehicle road speed
the control signal generator and providing alternate zones
of high and low control signal intensity along the road—
way, a vehicle speed network including a control signal
signal having a frequency corresponding to actual vehicle
road speed, means producing pulses of a frequency cor
receiving transducer carried by the vehicle and arranged 55 responding to the frequency of the vehicle road speed
signal, means counting the pulses at time intervals con~
so as to have a signal voltage induced therein modulated
trolled by the command speed signal and developing a
in amplitude at a frequency corresponding to the rate at
corresponding output signal, and control means respon
which the control signal receiving transducer passes
sive to the output signal and adapted so as to control
through the zones, detector, ampli?er, and differentiator
circuits successively arranged so as to develop peaked 60 vehicle movement and thereby cause the vehicle road
speed to be in some predetermined proportion to the
wave form pulses of a frequency corresponding to the
frequency of the control signal voltage, a command speed
network including a command signal receiving transducer
command speed.
frequency vcorresponding to the frequency of the com
mand speed signal voltage, another of the sources afford
15. In a device of the character described, the com
bination of a roadway having associated therewith plural
carried by the vehicle so as to have a signal voltage in
duced therein of a frequency corresponding to that of the 65 sources of signal energy, the plural sources being so ar
ranged relative to the roadway % to cause the signal
carrier wave from the command signal generator, detector,
energy to emanate from the roadway, one of the sources
ampli?er, and ampli?er inverter circuits successively ar
being selectively variable so as to provide a desired com
ranged so as to develop square wave form pulses of a
mand signal voltage, step-by-step counting circuits each 70 ing a road speed signal voltage, a throttle controlled
being connected both to the vehicle speed network and
vehicle carried command speed and road speed pickup
the command speed network so as to have the peaked
wave form pulses and the square wave form pulses ap
me ans each responsive to the signal energy from its asso
ciated source so as to provide respectively a command
plied respectively thereto, the square wave form pulses
speed signal voltage having a frequency corresponding
to one counting circuit being taken from one side of the 75 to desired speed and a vehicle road speed signal voltage
3,018,867
12
1 1'
having a frequency corresponding to actual vehicle road
speed, means producing pulses of a constant amplitude
and of a frequency corresponding to the frequency of
the vehicle road speed signal voltage, means producing
pulses of a frequency corresponding to the frequency of
the command speed signal voltage, counting means deter
mining the difference in frequency between the vehicle
road speed and command speed pulses and developing a
corresponding output voltage, and means responsive to
the output voltage and adapted to alter throttle settings 10
so that vehicle road speed is caused to be in some pre
determined proportion to command speed.
References Cited in the ?le of this patent
UNITED STATES PATENTS
1,767,609
2,454,659
2,493,755
2,576,424
2,661,070
2,803,743
2,883,975
Murray ______________ __ June 24,
Leonard _____________ __ Nov. 23,
Ferrill _______________ __ Jan. 10,
Su-nstein _____________ __ Nov. 27,
Ferrill ________________ __ Dec. 1,
Ballerait _____________ .__ Aug. 20,
1930
1948
1950
1951
1953
1957
Spetner ______________ __ Apr. 28, 1959