Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
ROAD VEHI CLE CONTROL S~rSTEM
Technical Field of the In~ention
This invention relates generally to motor vehi-
cle guidance and control systems and specifically to
systems having magnetic sensors and control circuitry on
the motor vehicle for developing control signals from
control devices placed along or embedded in the road~ay
over which the vehicle is traveling.
Background of the Invention
Many systems have been proposed for the control
of motor vehicles along a roadway through the use of sen=
sors on the ~ehicle which cooperate with signal devices on
the roadway for determining the position of the vehicle on
the roadway. The signal devices on the roadway can take
the form of electrical wires or magnetic material embedded
in the roadway surface at predet~rmined locations, such as
along the center of a lane, at the edges of a lane or some
other predetermined location or pattern. The sensors are
positioned on the vehicle to detect proximity to the
signal areas of the roadway, as by a magnetic pickup for
example, and the sensors therefore develop signals indica
tive of the position of the vehicle with respect to the
predetermined signal area of the roadway. The prior sys-
tems use electronic controls which operate from the posi-
tion signals to provide steering comma:nds to automatically
steer the car along the roadway. Such systems promise -the
potential of safer travel by reducing or eliminating acci-
dents due to vehicles straying off the appropriate lane of
travel and colliding with other vehicles or objects.
Despite the po-tential advantages of such sys-
tems, and despite the fact that a nun~er of such systems
have been proposed over a number of years in the prior
art, motor vehicle guidance systems for roadways have not
come into practical widespread use. It is believed that
the reason such systems have not come into widespread use
is because of their cost, both in terms of -the si~nal
devices for the roadway as well as the cost of the e~uip-
ment for the vehicles, and also because of concern as to
the complexity and reliability of the systems. My co-
pending U. S. patent application Serial No. 88,604, filed
October 26, 1979, discloses a relatively low cost but
effective way of making magnetized control strips for
roadways, and the present invention provides a simple, ye~
reliable and effective control apparatus for the moving
vehicle to provide steerin~ commands either to a driver or
to an automatic steering servo system, as well as speed
control siynals to a driver or an automatic speed control
when approaching speed zones, dangerous curves, and the
like.
Summary of the Invention
The present invention provides a motor vehicle
control system for use with a roadway~ having a plurality
of magnetic lane marking elements which are located in a
pattern indicative of the center or the lateral edges of
the lane, and of lower speed control æones such as curves
or intersections in the roadway. Sensing means are
attached to a motor vehicle for sensing the proximity of
the lane marking elements and generat:ing signals indica-
tive of the position of the motor vehicle with respect to
-the lane of travel. These signals are received by a
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control means which is operative in response to the sig-
nals to produce control signals indicative of the position
of the motor vehicle on the roadway and of the presence of
any lower speed zone. Also included are indicating means
which are operative in response to the control signals to
produce an indication to the driver of any corrective
action -that needs to be taken in terms of steering inputs
or speed reduction. The indicating means may be either an
audible or visual alarm. In the preferred embodiment, the
indicating means consists of four separate elements includ-
ing a general alarm signal, a slow signal, a turn left
signal and a turn right signal.
Guidance means are included and are operative in
response to the control sig;nals to produce a steering
signal which may be input to a servo steering device. The
servo steering device responds to the steering signal and
automatically controls the path of t:he motor vehicle on
the roadway. A signal output to an automatic speed con-
trol system commands a lower speed in a zone marked for
lower speed.
According to one embodiment of the inven-tion, an
array of sensing means is posi-tioned on the vehicle for
sensing left and right magnetic lane edge markers, and
also another pair of sensing means is positioned for
straddling magnetic center-of-lane markers. Connecting
means, which may include switching means, are provided for
connecting the sensing means to the various inputs of the
control means so that the control system is easily adapt-
able to operating on roads with a lan,--centers marker, or
with roads having lane edge markers.
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Brief Description of the Drawings
Figure 1 is a schematic plan view of a two lane
roadway showing the pattern of magnetic strips on the
roadway surface and a vehicle eq~lipped with sensing means;
Figure 2 is a block diagram showing the com-
ponents of the motor vehicle guidance system according to
the present invention;
Figure 3 is a schematic diagram of the logic
circuit and indicating signals of Fi~ure 2;
Figure 4 is a schematic diagram of the guidance
circuit of Figure 2;
Figure 5 is an alternate embodiment for the Lef-t
and Right sensors;
Figure ~ is a schematic pla:n view of a two l~ne
roadway showing a different pattern of magnetic strips on
the roadway surface and a vehicle equipped with an aray of
four sensing means;
Figure 7 is block diagram showing the connection
of the four sensor embodiment to the control means for use
on a roadway having lane edge markers; and
Figure 8 is block diagram similar to Figure 7
showing the connection of the four sensor embodiment to
the control means for use on a roadway having lane-center
markings.
Detailed Description of the Invention
With reference to Figure 1, one embodiment of
-the invention can be seen as it is utilized with respect
to a motor vehicle 10. The mo-tor vehicl.e 10 travels down a
roadway 11 which includes lateral lane edge marking ele-
ments 12 and transverse lane marking elements 13. Lanemarking elements 1~ and 13 are comprised of magnetic
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strips which are permanently aEfixed to or embedded
within the surface of the roadway. Mounted upon
motor vehicle 10 are a left sensing element 14,
a center sensing element 15 and a right sensing element
16. The sensing elements are operative to produce
sensing signals whenever a given sensing element
comes within close proximity of lane marking elements
12 or 13 in a manner which will be more fully des-
crlbed hereafter.
In Figure 2, sensing elements 14, 15, and 16 can
be seen to be identically comprised of magnetic core ele-
ments 20 and amplifiers 21. Sensing elements 14, 15, and
16 are connected to logic control circuit 22 by means of
leads 23, 24, and 25, respectively. Logic control circuit
22 is operative in response to the sensing signals re-
ceived to activate the proper indicating devices 26
through 29 and optional automatic spPed control servo 30
in a manner which will be more fully described hereafter.
Indicating devices 26 through 29 indicate the necessity
for turning right, turning left, slowing down or general
alarm, respectively, and they may take the form of visual
or audible indicators or both. In the preferred embodi
ment they may take the form of indicator lights.
Logic control circuit 22 i!; connected to guid-
ance circuit 33 by means of leads 34 and 35. Guidan~e
circuit 33, which is shown in detail in Figure 4, utilizes
the control signals transmitted on leads 34 and 35 to
produce steering signals which are transmitted to a servo
steering device 36 by way of lead 40. Also, the steering
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signals on lead 40 can be applied to an optional audible
indicator 37 to indicate the amo~lnt of steering correction
required.
Figure 3 shows a schematic diagxam of logic con-
t.rol circuit 22 and its connections to indicating lights
26 through 29. Lead 25 connects sensing signals from the
right sensing element 16 to the "R" input of logic control
circuit 22. Lead 25 connects to one input of an AND gate
41. Other branches of lead 25 connect to the anode of a
diode 42 and to one of the inputs of an AND gate 43. The
cathode of diode 42 connects to one of the inputs of AND
yate 44 whose output is connected through diode 45 to
"Alarm" indicating light 29 by way of lead 46. The ou-tput
of AND gate 41 appears at lead 50, a branch o which
connects to one of the inputs of AND gate 51. Other
branches of lead 50 connect to the anode of a diode 52
whose cathode connects to lead 46 and to the anode of a
second diode 53. The output of AND gate 51 is connected
to the "Slow" indicating light 28 by way of lead 54. The
~0 output of AND gate 43 is connected to the "Turn Left"
indicating light 27 through lead 55.
Lead 24 connects the output of the center sens-
ing element 15 to the "C" input of logic control circuit
22. The "C" designation stands for "common" or, in this
case "center" and refers to the fact that signals applied
to this input are from transverse lane marking elements
13, and apply to the operation of the vehicle as a whole,
rather than to left or right steering commands. In the
case of the embodiment of Figure 1 which has three sensors
on the vehicle, the common input sig~lal is also from the
center sensor 15, but this is not necessarily always the
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case, as explained further with respect to the embodiment
of Figures 6, 7, and 8, below. Lead 24 co~nects to one of
~he inputs of an AND gate 56 and also to the anodes of two
diodes 60 and 61. The cathode of diode 60 connects to
lead 46. The cathode of diode 61 is connected to the
cathode of diode 53 and the input: of an inverter 62
through branches of lead 63. The output of inverter 62 is
connected to one of the inputs of an AND gate 64 whose
output appears at lead 65. One branch of lead ~5 connects
to an inpu-t of AND gate 43 and anoth~er branch connec-ts to
an input of AND gate G6. The output of AND gate 66 is
connected to ~he "Turn Right" indicating light 26 through
lead 70.
Sensing sig~als from the left sensing element 14
are connected to the "L" input of log:ic control circuit 22
through lead 23. Lead 23 connects to the anode of a diode
71, to one of the inputs of AND gate 41 and to one of the
inputs of AND gate 66. The cathode of diode 71 is con-
nected to the cathode of diode 42 and to one of the inputs
of AND gate 44.
A switch 72 connects a logic 1 source 73 to
either an input of AND gate 44 in "MANUAL" position or
inputs of AND gates 56 and 64 in "AUTO" position. This
allows logic con-trol circui-t 22 to be operated in either a
manual or automatic mode as described more fully here-
after.
Leads 34 and 35 connect the outputs of AND gates
43 and 66, respectively to guidance control circuit 33 as
seen in Figures 3 and 4. With reference to Figure 4, it
can be seen that lead 34 connects to the non-invertin~ in-
put of an amplifier 74. The inverting input of amplifier
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74 is connec-ted to a six volt reference through lead 75.
The output of amplifier 74 connects through a diode 76 and
a resis~or 80 to lead 81, a branch of which connects to
the non-inverting input of a amplifier 82. The output of
amplifier 82 is fed back to its inv~erting input by way of
lead 83 so that amplifier 82 is a unity-gain current
amplifier. Lead 81 is connected to the six volt source
through resistor 84 and to capacitor 85 whose other side
connects to signal ground. Amplifiers 74, 86 and 82 are
connected to a 12 volt source of operating voltage, and
the 6 vol-t reference can be derived from the 12 volt
source by a resistor voltage divider clS shown.
Lead 35 is connected to the inverting input of
an amplifier 86. The non-inverting input of amplifier 86
is connected to lead 75. The output of amplifier 86
connects to the cathode of a diode 90. The anode of diode
is connected to lead 81 through resistor 91. The
output of guidance control circuit 33 appears a-t lead 40.
The signal at lead 40 may be input to a servo steering
device 36 as shown in FIGURE 2 which is capable of auto-
matically steering the motor vehicle.
An optional audible indicator 37 can be con-
nected to a branch of lead 40 as follows. A "sonalert"
transducer 95 is connected to a cliode bridge consisting of
diodes 96-99. One side of the bridge, consisting of the
anode of diode 96 and the cathode of diode 98, is con-
nected to a branch of lead 40. The other side of the
bridge, consisting of the anode of diode 97 and the cath-
ode of diode 99, is connected to a six volt reference at
lead 101. This reference voltage may be developed in any
known way, for example, by connecting a regulated six volt
6~
supply through a unity gain buffer amplifier 102.
The operation of the control system is as fol-
lows. As mo-tor vehicle 10 travels down roadway 11 in
FIGURE 1, whenever sensing elements 14, 15, or 16 come
within close proximity of a magnetic lane marking element
12 or 13, magnetic flux will be picked up its core 20 and
a sensing signal will be generatecl in its coil. The
sensing signal is then amplified by the corresponding
amplifier 21 which produces a logical 1 output signal if
10 the sensing signal is at sufficient magnitude. The resul-
tant effect is that a logical 1 is produced whenever one
of the sensing elements 14 through 16 crosses over one of
the magnetically treated lane marking elements 12 or 13.
For example, should motor vehicle 10 turn to the right,
right sensing element 16 will sense lane marking elements
12 as it passes over them. Thus, a series of logical l's
would be produced on lead 25 corresponding to the lateral
lane marking elements 12 that are passed. Should motor
vehicle 10 turn to the left, the logical l's will appear
20 on lead 23. Transverse lane marking elements 13 are placed
across -the entire lane and indicate that a lower speed
zone, such as for a sharp curve or intersec-tion, is being
approached. When elements 13 are crossed by the vehicle,
each one of sensing elements 14, 15, and 16 will generate
a logical 1 at output leads 23 through 25, respectively.
With reference -to Figure 3, it can be seen that
logic control circuit 22 may be set in either a manual or
an automatic mode depending upon the position of switch
72. The circuit is :in the manual position if switch 72 is
30 set so that the logic 1 source 73 is connec-ted to the
input of AND gate 44. The circuit is in the automatic
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position when switch 72 is set such that the logic 1
source 73 is connected to the input of AND gate 56.
When switch 72 is set in the manual position, it
can be seen in Figure 3 that a logical 1 signal on any of
leads 23, 24, or 25 will activate alarm indicatlng light
29. For example, if a logical 1 signal appears at either
sensing lead 23 or sensing lead 25, it will appear at the
top input oE AND gate 4~. A logical 1 is also applied
constantly to the lower input of .~ND gate 44 through
switch 72 so that the output is a logical 1. This passes
through diode 45 and through lead 46 to alarm indicating
light 29. Should a logical 1 appear at the "C" input,
lead 24, from the center sensing element 15, it will pass
directly through diode 60 to alarm indicating light 2~ by
way of lead 46. Thus, any combination of sensing signals
will activate alarm indicating light 29 when switch 72 is
in the manual position. Indicators 26, 27 and 28 are
inhibited by the logic in manual position and do not
respond to any combinations of left, right, or center
signals. Switch 72 would be in the manual position for
most in-town situations.
With switch 72 in the automatic position, alarm
indicating lights 26, 27 and 28 may be activated under the
proper circumstances. For example, ,hould motor vehicle
10 deviate slightly to the right so that right sensing
element 16 passes over a lateral lane marking element 12,
a logical 1 signal will appear on lead 25. This places a
logical 1 at one input of AND gate 43. Assuming the
vehicle is not also crossing a transverse mar~er 13, a
logical 0 is present on leads 23 and 24, and this causes
inverter 62 to apply a logical 1 one input of AND gate 64.
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~9~51 65
The other input to AND gate 64 is also at a logical 1
since it is connected to logical 1 source 73. Therefore,
the output of AND gate 64 is at logical 1, causing a
logical 1 signal to appear at the output of AND gate 43.
This activates the left turn indicating light 27.
By a similar analysis it can be seen that logi-
cal 1 sensing signals being received on lead 23 from lef-t
sensing element 14 will produce a :Logical 1 on lead 70
which activates the turn right indicating light 26.
Should motor vehicle 10 approach a section of
the roadway marked with transverse :Lane marking elements
13, logical 1 signals will simultaneously appear at each
of leads 23, 24, and 25. Transverse lane marking elements
13 are used to signal a reduced speed or danger ~one such
as a sharp curve or intersection. With reference to
Figure 3, it can be seen that a logical 1 appearing at the
"~" input, lead ~4, from center sensing element 15 will be
inverted by inverter 62 and appear at the lower input of
AND gate 64 as a logical 0, thus inh:ibiting both gates 43
and 66 and the left and right indicators 26 a~d 27. This
prevents the L and R signals from activating TURN RIGHT or
TURN LEFT indications, respectively, since the L and R
signals were the result of crossing a transverse marker
13, and not the result of the car deviating laterally in
the roadway. Leads 23 and 25 apply logical l's to AND
gate 41 and thus a logical 1 appears on output lead 50
which connects to one input of AND gate 51. Lead 24 from
the center sensing element 15 and the logic 1 f~om source
73 cause gate 56 to apply a logical :L to the other input
of gate 51, causing a logical 1 to appear on lead 54 thus
activating the slow indica-ting light 28. The signal on
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lead 54 can also be applied to an automatic speed control
servo 30 for the vehicle, which can be programmed to
reduce the speed of the vehicle automatically from a high
cruising speed to a lower speed for the duration of the
zone marked by transverse markers 13.
The crossing of the transver.se lane marking ele-
ments 13 will also activate alarm indicator 29, either
through the signal path from the "C" inpu-t through lead 24
and diode 60, or the "L" and "R" signal from gate ~1
through diode 52. Optionally, it may be desirable in some
circumstances to delete the connection from gate 41
through diode 52 to the alarm 29, and this is indicated in
Figure 3 by the X marking, reference number 57. This
would prevent simultaneous Left and Right signals from
activating the alarm. This disconnection would be used
for certain roadway marking patterns that would have the
effect of creating egual L and R signals to control the
vehicle's path down the center of a lane. In such a
system the equal L and R signals would indicate proper
location of -the vehicle, no-t a low speed or alarm situa-
tion. However, the signal at lead 24 would continue to
give the alarm for a low speed or danger zone, since the
transverse marker 13 would be picked up by the center
sensor 15, and the signal would be transmitted -through
diode 60 to the alarm indicator 2~.
Also, in the event that the vehicle should drift
toward the right or the left and if the left or right
sensor or associated circuitry were to fail, the center
sensor 15 would provide a backup alar~ when the car moved
sufficiently laterally that the center sensor would pick
up the left or right lane divider marker 12.
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The logical 1 signals appearing on leads 55 and
70 are transmitted to guidance control circuit 33 by wa~
of leads 34 and 35, respectively. With reference to
Figure 4, the voltage at leades 81 and 40 is normally -~6
volts in the absence of input pulses, due to the bias
provided from the 6 volt reference. As motor vehicle 10
approaches the right lateral lane marking elements 12,
logic control circuit 22 causes positive pulses to occur
on lead 34. Each pulse causes the output of amplifier 74
to go to its full output of +12 volts. This causes diode
76 to conduct passing current through resistor 80 and
causing capacitor 85 to begin to charge from ~6 volts
towards a more positive value. As more magnetic lateral
lane marking elements 12 are passed, more pulses will be
generated to charge capacitor 8~ and thus the voltage
across capacitor 85 will approach closer to 12 volts.
This voltage appears at lead 81 and is input to the posi-
tive input of unity gain current amplifier 82.
As the motor vehicle approaches the left lateral
lane marking elements 12, logic control circuit 22 causes
positive pulses to appear on lead 35. These pulses are
connected to the inverting inpu-t of amplifier 86 causing
its output to go to 0 volts. This allows diode 90 to
conduct current through resistor 91 from lead 81. This
discharges capacitor 85 and lowers the vol-tage at lead 81
from ~6 volts towards 0 volts. Thus, as more marking
elements are passed, the voltage across capacitor 85 will
approach closer to 0 volts.
The steer:ing signals from lead 81 are passed
through unity gain current amplifier 82 and are applied to
a servo for controlling the steering of the vehicle. The
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design of s-teering servos is known in the art and is not
set forth in detail here. The servo steering device 36
shown in ~igure 2 is designed to accept inputs such that
+12 volts equals full left, 0 volts e~uals full right, and
+6 vol-ts equals no steering correction. Of course the
particular voltages used for the steering commands are nct
critical, but could be changed by simple circuit changes.
For example, O could equal no change, with + and - indi-
cating turns. The inpu-t of the steering servo would be
changed accordingly.
The time constants between resistors 80 and 81
and capacitor 85 control the amount of immediate co~rec-
tion per positive pulse. The time constant between resis-
tor 84 and capacitor 85 controls the recovery time between
the last pulse and the straight ahead condition.
The optional audible indicat;or 37 operates from
the steering signals as follows. When the vehicle is
properly positioned laterally on the :road and no steering
correction is called for, the signal at lead 40 of Figure
4 will be +6 volts. The audible indicator circuit 37 is
designed under those conditions to produce no audible
output. The sound transducer 95 then receives no voltage
differential, since the 6 volt signal at lead 40 is
matched by the 6 volt reference at lead 101. The sound
transducer 95 will produce a sound wi-th increasing loud-
ness as the signal voltage at lead 40 deviates in either
direction from the +6 reference by increasing amounts.
The sound transducer 95 thus produces an audible indica-
tion, in -terms of the loudness of the sound, of the degree
of steering correction required, and this in -turn provides
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another type of warning indication to the vehicle opera-
tor. It will be appreciated that in the event that the
guidance circuit 33 is designed to operate at different
reference voltages or polarities, circuit 37 would be
designed accordingly to still achieve the above-described
opera-tion.
An optional embodiment for the left and right
sensors is shown in Figure 5. In Figure 5 the alternate
left sensor 14A and alternate right sensor 15A are shown.
They are in most respects similar to sensors 14 and 16 of
E'igure 2, but with the addition of potentiometers 104 and
106, respectively. With reference lo left sensor 14A,
potentiometer 104 is connected across the coil 20 of the
sensing core. The ~ariable tap of the potentiometer 104
connects to the amplifier 21. By adjusting the position
of the variable tap of the potentiometer, the gain or
sensitivity of the sensor is adjusted. Sensor 16A is
similarly connected with potentiometer 106.
Potentiometers 104 and 105 are preferably linear
taper sharing a common shaft or other mechanical actuation
as indicated by broken line 107. They are arranged so
that with clockwise rotation of the shaft, potentiometer
186 is moved towards its minimum output, while potentio-
meter 104 moves towards its maximum output. The converse
occurs with counterclockwise movement.
These potentiometers allow for adjusting the
system to keep the vehicle at egual distances from the
lane edge markers should the magnetic strengths of -the
markers be different. In this regard, the controls can be
thought of as a balance or offset control to fine tune the
centering of the vehicle on the lane. This alternate
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embodiment of Figure 5 would not be used if the magnetic
marker were down the center of the lane, but may be of
advantage where the magnetic lateral lane maxkers coincide
with the visible lane dividers.
Referring now to Figure 6, there is shown an
al-ternate embodiment of the invention utilizing an array
of a plurality of sensors of the vehicLe which can be con-
nec-ted in different patterns to enable the vehicle to
operate on roadways having different types of lane mark-
ings. In Figure 6, vehicle 110 has four such sensorsnumbered 121 through 124. Sensor 121 is on the lef-t side
of the vehicle and sensor 124 is on the right side of the
vehicle. These sensors correspond respectively -to sensors
14 and 16 of vehicle 10 of Figure 1. Sensors 122 and 123
are located more centrally of vehicle 110, being spaced
apart on either side of center with respect to vehicle
110 .
Roadway 111 of Figure 6 is a two lane highway
and vehicle 110 is shown traveling do~m one of the lanes.
Dotted line 117 indicates the center of the roadway divid-
ing the lanes, but in the embodiment of Figure 6 dotted
line 117 is not a magnetic marker. Instead, the lanes are
indicated by lane-center markers 112 which are positioned
to run down the center of the lane of travel. There would
be corresponding markers in the center of the other lane
of roadway 111, but these have been omitted for purposes
of clarity in Figure 6. Markers 11:2 are analogous to
markers 12 of Figure 1 in that they define the lane of
travel but instead o:E marking the edges of the lane as in
Figure 1, markers 112 mark the center of the lane. Trans-
verse markers 113 are substantially identical to trans-
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verse markers 13 of Figure 1, and serve the same purpose
which is to mark zones for a lower speed ~.one. As vehicle
110 proceeds down the lane of tra~el it is positioned
laterally of the lane so that sensors 122 and 123 bracket
or straddle the center of the lane as defined by magnetic
markers 112.
Use of the array of sensors, numbering four in
the example shown in Figure 6, permits the vehicle and
control system -to be operated either on a lane~center
marked roadway as in Figure 6, or on a lane-edge marked
roadway as in Figure 1. Figure 7 shows the connection of
the sensors to the control system of Figure 2 for use on a
lane-edge marked roadway as in Figure 1. In Figure 7,
reference llOa indicates the front portion of vehicle 110,
and sensors 121 through 124 are spaced along the vehicle
as previously described, -to represe:nt a plan view when
viewed from the top. Magnetic marking elements 112 are
spaced along the left and right hand margins of the lane,
and transverse marker 13 extends across the lane as pre-
viously described with respect to Figure 1. A connec-ting
means 130 is provided for connecting sensors 121-124 to
the inputs of logic circuit 22. Connecting means 130
could take the form a terminal strip in which the neces-
sary wiring connections are made to adapt the control
system to one roadway marking system or the other or
alternatively, connecting means 130 could comprise switch
ing means whereby the vehicle-mounted control system can
be configured for one roadway system or the other by
actuation of -the switch. In Fic~lre 7, connecting means
130 is configured -to apply signals fr.om sensor 124 to the
"R" input of logic circuit 22 via lead 25~ Sensor 121 is
i5
connected to connecting means 130 to lead 23 to the "L"
input. This corresponds to the connection of sensors 16
and 14 to the "R" and "L" inputs, respectively, for the
embodiment of Figures 1 and 2 previously described. The
center or common input "C" receives signals from both
sensors 123 and 122. Connecting means 130 connects both
of these sensors to lead 24 to the "C" input. This connec-
tion can be a series one or a parallel one. If sensors
122 and 123 are connected in series, greater sensitivity
will result, but re~uires somewhat more complex switching.
A parallel connection of sensors 122 and 123 give somewhat
lower sensitivity, but simpler and perhaps more reliable
switching. If the connection changes are made on a termi-
nal strip for connecting means 130, a series connection of
sensors 122 and 123 would be preferred. Control circuit 22
connects to the guidance circuit alarms and indicator in
the same m~nner as previously descr:ibed with respect to
Figure 2, but these connections are omitted from Figure 6
for purposes of clarity.
In operation, the embodiment of Figure 7 oper-
ates the same as the embodiment of Figures 1 and 2 pre-
viously described. Sensor 121 provides steering signals
to the "L" input, sensor 124 provide steering signals to
the "R" input, and sensor 122 and 123 jointly provide
common signals ~rom the transverse markers 13 to the "C"
input.
In the embodiment of Figure 8, connecting means
130 has been rewired or switched to permi-t operation of
the vehicle on a lane-center marked roadway as in Figure
6. In this configuration, sensor 122 picks up signals
from magnetic markers 112 when the vehicle has moved too
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far to the right, and sensor 122 is connected to the "R"
input of control logic 22. Sensor 123 senses when the
vehicle has moved -too far to the left, and its is con-
nected through connecting means 130 and lead 23 to the "L"
input. Sensors 121 and 124 are both connected by con-
necting means 130 -to lead 2~ to the "C" input. These
sensors jointly detect crossing of transverse markers 113,
and in a back-up mode in the event of failure of one of
sensors 122 or 123, would detect crossing of the lane
center markers 112. Sensors 121 and. 12~ can be connected
in series or parallel to the "C" inout in the same manner
that was described above with respe,~t to sensors 122 and
123 in Figure 7. The design of a suitable switch or
switching network for connecting means 130 is within the
skill of those in the art, and could be irnplemented
through switches, relays or solid state switching. De-
pending upon whether serial or par~llel connections are
used, the switching could be upstream or downstream of the
of the amplifiers 21 that would be provided for each
sensor, as would be apparent to those skilled in the art.
In the operation of the embodiment of Figure 8,
sensors 122 and 123 provide the st:eering commands, and
sensors 121 and 12~ provide the low speed control commands
when the car travels into a zone marked by transverse
markers 113. The rest of the con-trol sys-tern from logic
circuit 122 through the guidance, steering servo, audible
indica-tor and various alarm and in.dicator functions is
exactly the same as previously described above with refer-
ence to Figures 2 and 3. The four--sensor embodiment of
Figures 6, 7 and 8 thus provides a convenient means for
adapting or reconfiguring the control system for use on
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s
different road marking systems.
Although Figure 6 shows the lane markin~ ele-
ments in the center of the lane of travel, it will be
appreclated that they could be offset from center by a
prede-termined distance, and the two center sensors on the
vehicle would be positioned accordingly to place the
vehicle at the desired position in the lane. Also, the
sensors do not have to be at the front of the vehicle as
shown in the drawings. They could be placed elsewhere on
the vehicle, for example beneath it, spaced laterally of
the vehicle as described.
The sensitivity adjustment technique described
above with reference to Figure 5 is also applicable to the
embodiment of Figures 6, 7, and 8. The adjustment would
be applied to sensors 121 and 124 for lane-edge marked
roadways, and sensors 122 and 123 for lane-center marked
roadways, for centering the vehicle in the lane of travel.
Thus the present invention provides a control
system having manual and automatic modes, for providing
warning, steering, and speed siynals for control of a
vehicle traveling along a roadway.
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