Note: Descriptions are shown in the official language in which they were submitted.
2~1373
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This invention relates generally to a vehicle control
system for directing a free-steered vehicle operating
along a predetermined path. In particular, this invention
relates to a control system having a re*lective code
mounted along the path such as in a mine, wave form signal
producing and sensor means mounted on the vehicle and a
microprocessor for directing various operations of the
vehicle in response to the code and to automated vehicles.
Mining operations are labor intensive. The automation of
certain operations, particularly those which are largely
repetitive has certain advantages. There is the potential
of labor savings and a lower risk of harmful accidents.
In particular, for example, in underground mines haulage
trucks are used to transport mined material from the mine
stope along a drift or tunnel to a box hole where the
material is dumped. The current practice involving
operator driven trucks has a number of disadvantages. The
operator's cab is located at the front of the truck and
the rear view from the cab is thus obstructed. Forward
operation of the truck in the tunnel is therefore
preferred and a turn-around zone for the truck is provided
at either end of the tunnel. Excavation of the
turn-around zones adds expense to the mining operation.
Additionally, turning the truck around increases the
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length of time of each trip and increases wear on the
truck and in particular its tires. Operation of large
mining vehicles is a source of back injury to drivers.
:~
Thexe is known Canadian Patent No. 1,135,813 which
describes a line follower vehicl2 having a scanning head.
A fluorescent guide line is floor-mounted and code spikes
project laterally from the line. A light on the vehicle
causes the line to fluoresce and a sensing head detects
the fluorescence. A microprocessor is connected to the
sensing head and vehicle controls to guide the vehicle
along the fluorescing guide line. Additional commands
which, for example, cause the vehicle to follow along the
right or left side of a fork in the guide line are
followed in response to the detection of a spike.
U.S. Patent 3,628,624 of Biere Patent AG describes a
guidance system for self-propelled trackless carriages. A
strip of conductive iron is laid down the center of the
guidepath from which sensors mounted below the carriage
can assess the relative position of the vehicle. The
vehicle has two driving wheels and is steered by
adjustments of torque to the driviny wheels. Coded
magnets located at various positions along the pathway are
used to provide command information. This command
20~373
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information is acquired by use of a different set of
sensors than is used for the primary guidance function.
Canadian Patent 1,193,696 assigned to Imperial Chemical
Industries PLC describes a vehicle guidance system
particularly for use in agriculture. The system provides
information to an operator of a tractor so that a field
may be efficiently covered without overlap. A vertically
scanning laser is forwardly directed and a retroreflective
fixed target at the end of a straight path reflects the
laser signal. The target is coded so that deviations of
the tractor from the path are sensed and an appropriate
signal sent to the operator so that steering may be
corrected.
A vehicle control system for use in any mining operation,
under or aboveground, should satisfy a number of
criteria. It preferably: functions with a vehicle which
weighs several tons, even when empty; functions with a
vehicle operating on an uneven surface which may also be
sloped; and functions in the dirt and dust o~ a mine~
Preferably, a control system also controls a vehicle being
driven in forward and reverse directions. This, in many
instances, eliminates the need to turn the guided vehicle
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2 ~ 4~
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around ~t each end of its path and thus saves time and
vehicle wear. It may reduce or eliminate the need for
turn-around zones.
~,
Further, the system preferably has a collision avoidance
system so as to avoid running into other vehicles,
personnel, etc.
It is preferable that the control system may be used to
retrofit an existing vehicle.
Preferably, the control system directs other vehicle
operations such as stopping at predetermined locations,
dumping at one or more predetermined locations, and
testing of vehicle brakes. Further, the system preferably
monitors various aspects of vehicle function such as oil
pressure and engine temperature.
In a broad aspect, this invention provides a vehicle
control system for directing vehicle operations, including
guidance of the vehicle forwardly and rearwardly along a
predetermined path. There is a retroreflective coded
longitudinal reEerence means elevatedly mounted above
ground level along the path. There is a first scanning
wave-form signal producing means mounted on the forward
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portion of the vehicle and a first sensor means associated
with the first signal producing means mounted on the
forward portion of the vehicle. The signal producing
means and sensor means are "associated", that is mounted
such that the sensor means may receive signals which have
been deflected or "retroreflected" back along a path
parallel to and substantially the same as the path of a
signal emitted from the signal producing means. There is
also a second scanning wave-form signal producing means
and associated sensor means mounted on a rearward portion
of the vehicle. The first signal producing means and its
associated sensor means are mounted on the vehicle and the
coded reference means is mounted such that the signal
producing means and the sensor means are in a
retroreflective path of the reference means when the
vehicle is positioned to travel forwardly along the path.
Correspondingly, the second signal producing means and its
associated sensor means are mounted on the vehicle and the
reference means is mounted so that the second signal
producing means and the second sensor means are also in a
retroreflective path of the reference means when the
vehicle is positioned to travel rearwardly along the
path. There is a microprocessor means operably connected
to the signal producing and sensor means such that signals
emitted from either of the scanning signal producing means
retroreflected by the coded reference means and detected
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by the associated sensor means may be relayed from the
sensor to the microprocessor means where they are
processed. Directing means for vehicle operations such as
~teering and braking are responsively connectPd to the
microprocessor means and may be controlled according to
the processed signals whereby the vehicle is directed to
move forwardly and rearwardly along the path.
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Preferably each signal producing means is a scanning laserwhich is mounted to scan a path transversely of the
longitudinal reference means so as to cross the width of
the reference means.
In a preferred embodiment, the longitudinal reference
means may comprise a guidance strip, code markers
containing bar code and speed markers each speed marker
being in the shape of a symmetrically tapered trapezoid.
Preferably there are two sets of markers, one set arranged
on each side of the guidance strip so that one set along
with the guidance strip provides coded information for a
vehicle travelling in one direction along the pathO The
second set of markers and the guidance strip provide coded
information for a vehicle travelling in the second,
opposite direction along the path.
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In another broad aspect, the invention comprises a vehicle
control system having a substantially continuous
retroreflective coded longitudinal reference means
elevatedly mounted along an endless path such as a circle,
oval, etc. The reference means comprises a guidance
strip, code markers and speed markers. The vehicle has a
scanning wave form signal producing means and associated
sensor means mounted on it so as to be in a
retroreflective path of the reference means when the
vehicle is on the path. There is a microprocessor means
operably connected to the signal producing means and
sensor means for processing signals reflected from the
reference means and received by the sensor means.
Directing means are responsively connected to the
microprocessor means for directing the vehicle in response
to the processed signals whereby the vehicle may be
directed to move along the path.
In one preferred aspect, the vehicle is an articulated
dumping vehicle.
In preferred embodiments, each coupled or associated
signal producing means and sensor means form a unit and in
at least one preferred embodiment each unit may be, as
appropriate, retractably mounted on the vehicle so as to
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have an operable position and a retracted position. In
the preferred embodiment for use with a dumping vehicle
there is a rearward unit retractably mounted on an
underside of the dump box. When the vehicle travels in
its rearward direction, the rear unit occupies its
operable position, but may be retracted when not in use.
Preferably the unit would be surrounded by a casing when
in its retracted position so as to be protected when the
dump box is being loaded, for example. Preferably the
unit is mounted by means of a hinge or sliding track
arrangement and is operably connected to a drive means
such as a hydraulically driven cylinder for movement
between its operable and retracted positions.
Preferably, and particularly for safety reasons, a
collision avoidance system may form part of the vehicle
control system. When electromagnetic waves of a
predetermined frequency from a transmitter mounted on
another object or person are received by a collision
avoidance antenna mounted on the automated vehicle certain
collision avoidance procedures would be taken under the
direction of the microprocessor means. Preferably such a
transmitter, worn by a person working in the mine and
mounted on other vehicles which may cross the path of the
automated vehicle, would actually be a passive transponder
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which transmits a signal in response to receipt of a
signal, or, alternatively, an active battery powered
transponder which transmits a signal on a continual short
burst (pulse) basis. For a passive transponder the
vehicle thus preferably has mounted onto it a microwave
transmitter which transmits a microwave signal of a first
frequency. When received by the passive transponder a
microwave signal of a second frequency is retransmitted.
A microwave receiver mounted on the truck, relays an
electronic signal to the microprocessor means upon receipt
of the transmitted or retransmitted signal. The
microprocessor then directs the collision avoidance
procedure.
An automated vehicle may be, according to a preferred
embodiment, provided with a signal sensor, such as an
infrared signal sensor operably connected to the
microprocessor means whereby certain operations of the
truck may be controlled by a remote operator by use of an
infrared transmitter. Further a vehicle may be fitted
with an infrared transmitter so as to enable preprogrammed
communication with a second vehicle having an infrared
signal receiver.
2a~37,3
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In the drawings, which illustrate embodiments of the
-~ invention,
.` Figure 1 is a partial cut-away view of a conventional
~ underground mine showing the pat:h along which an operator
: driven truck travels;
: Figure 2 is a partial cut-away view of an underground mine
showing the path along which an automated vehicle travels;
Figures 3-6 show front, side, top and rear plan views
respectively of a typical underground hardrock mining
truck located in a drift, retrofitted with a preferred
embodiment control system in accordance with this
invention;
''
Figure 7 is a schematic diagram of the truck mounted
aspect of a preferred embodiment control system showing
the computer components, inputs and outputs;
Figure 8 is a three-dimensional view of a transmitting and
receiving antenna of the collision avoidance system
Figures 9 and 10 are top and side cut-away plan views
respectively of the rear scanning laser and sensor unit of
a preferred embodiment in a concealed position;
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Figures 11 and 12 are top and side cut-away plan views
respectively of the rear scanning laser and sensor unit of
a preferred embodiment in a deployed position;
Figure 13 is a plan view of a typical layout of a guidance
strip, code markers and speed markers as mounted on a mine
roof as viewed from below;
Figure 14 is a diagramatic representation of the 90
reading window of the scanning laser component of the
preferred embodiment;
Figure 15 illustrates diagramatically the signal read by a
sensor due to a single scan of the laser along line 105 of
Figure 13;
Figure 16 shows the possible bar code patterns for six
event codes of the marker codes of the preferred
embodiment of this invention;
.
Figure 17 is a top view of the control codes and laser
sensors correlating which codes are read by which sensors
and the travelling direction of the vehicle;
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- 12 -
Figure 18 is a top view of a turnaround zone in a drift
for an automated vehicle according to a preferred
embodiment of this invention;
Figure 19 is a top view of a siding in com~ination with a
turnaround zone for an automated vehicle according to a
preferred embodiment of this invention;
Figure 20 is a top view of a dump zone in a drift for an
automated vehicle according to a preferred embodiment of
this invention;
Figure 21 is a schematic of a guidance strip, code markers
and speed markers of a preferred embodiment control system
for use on an endless path vièwed from above:
Figures 22 and 23 are side and top views respectively of a
typical underground hardrock mining truck located in a
drift, retrofitted with a preferred embodiment control
system in ac ordance with this invention;
Figure 24 is a rear view of a typical underground hardrock
mining truck located in a drift;
Figure 25 is a top plan view of the rear scanning laser
and sensor unit of an alternate preferred embodiment in
its concealed position;
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Figure 26 is a partial sectional view of the unit of
Figure 25 taken along 26-26; and
'
Figure 27 is a partial sectional view of the unit of
Figure 25 taken along 27-27, the unit being in its
operable position.
; Figure 1 shows a conventional underground mining operation
having a turn-around zone 2Q at each end 22, 24 of drift
26. Figure 2 shows a mining operation as envisioned to be
made possible by the use of a guided vehicle in which a
dump truck follows path 28 directly between stope 30 and
box hole 32.
Figures 3-6 show a typical dump truck 34 retrofitted with
vehicle components of the control system. The truck is
shown in a drift which is, typically, twelve to fi~teen
feet in height and fourteen to sixteen feet in width.
~.,,
The system microprocessor means are contained in deck
enclosure 36 and are made up of a CPU, RS422 interface,
laser co-processing interface, digital and analog input
and output racks, infrared control relay, collision
avoidance transmitter~receiver, proportional steering
valve interface, and field terminal strip.
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A second deck enclosure 38 contains a +5vdc power supply,
+/-15vdc power supply, +24vdc power supply, and a 24vdc to
24vac converter.
The truck is equipped with various "system inputs"
including sensors which provide information that is
processed by the CPU into "system outputs", in the form of
electrical output signals which direct various operations
of the truck. The general layout of the control system
vehicle components is shown in the schematic diagram of
Figure 7.
The system provides a front infrared signal sensor 40 and
rear infrared signal sensor 42. The rear sensor is
located for protection between the rear tires and under
the dump box of the vehicle. There is a handheld infrared
transmitter 44 for use by an operator. An operator may
use the transmitter to command certain operations of the
truck from a remote location. For example, a loaded truck
may be set moving in a rearward direction along the path
of Figure 2 from the stope 30 towards the box hole 32.
The truck is optionally provided with front and rear
infrared signal transmitters 43, 45 respectively, operably
connected to the microprocessing system, the use of these
being described further below.
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- 15 -
There is a front-mounted collis:ion avoidance system 46 and
a rear-mounted collision avoidance system 48 mounted in
the vicinity of the rear infrared sensor. Each collision
avoidance system, operably connected to the
microprocessing system, transmi1:s electromagnetic waves of
a first predetermined frequency and receives
electromagnetic waves of a second predetermined
frequency. In the preferred embodiment, the collision
avoidance system transmits microwave signals at 912 MHz
and receives microwave signals at 1830 MHz. Each of the
collision avoidance systems are the same and one is
illustrated in Figure 8. It comprises a transmitting
antenna 49, test transponder 50, receiver antenna 51 and
i~ mounted to the truck by means of isolator and
stiffening panel 52. Local transmitters remote from the
vehicle which transmit electromagnetic waves at the second
prede$ermined wavelength are mounted on other movable
things remote from the vehicle but which may cross the
path of the vehicle. The receiver of the collision
avoidance system, antenna 51, is operably connected to the
microprocessor means 50 that the vehicle is directed by
the microprocessor to 5top if waves at the second
wavelength are received by the antenna. Local
transmitters are provided by transponders 53 which are
mounted on the clothing of personnel working in the mine,
,
3 ~ 3
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other vehicles working in the mine, and anything else
which may cross the path of the automated vehicle. Such a
transponder is activated by incident microwave signals 57
received from a transmitting antenna a predetermined
minimum distance from the antenna and retransmits the
signal at 1830 MH2. The microprocessor is programmed to
stop the truck when it determines that a retransmitted
signal 59 has been received by one of the antennae.
An alternative to the passive transponder system is a
vehicle mounted collision avoidance system 312 mounted in
the vicinity of the deck enclosure 36. The collision
avoidance system is operably connected to the
microprocessing system and receives electromagnetic waves
of a predetermined frequency. In the preferred
embodiment, the collision avoidance system receives
electromagnetic waves at 350 MHz. This alternative
vehicle mounted collision avoidance system is illustrated
in Figures 22 and 23. It includes receiver antenna 313
and processing electronics 314. Local active transmitters
316, remote from the vehicle which transmit
electromagnetic waves at a predetermined frequency are
mounted on or carried by other objects or persons remote
from the vehicle but which may cross the path of the
vehicle. The receiver of the collision avoidance system,
2 1~ 7 3
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antenna 313, and the interpreting electronics 314, are
operably connected to the microprocessor msans so that the
vehicle is directed by the microprocessor to stop if waves
are received by the antenna. Local transmitters are
provided by active transponders 316 which may be mounted
on the clothing of personnel working in the mine, other
vehicles working in the mine, and anything else which may
cross the path of the automated vehicle. Such an active
transponder is powered by a small battery and transmits at
350 MHz in short bursts i.e. pulses every 600 milliseconds
for a period of 2 milliseconds. The microprocessor is
programmed to stop the truck when it determines that a
transponder signal has been received by the antenna.
'
There is an optional destination switch referred to here
as an "ore/waste" switch 54 which governs the destination
of the vehicle. The switch can be manually operated and
would be used, for example, in situations in which there
are two dumping sites; one box hole for dumping ore and
one for dumping waste. The switch is also connected via
the microprocessor to the infrared sensor system in order
that the position of the switch and therefore the
destination of the vehicle can be checked or reset by a
remote operator using the handheld transmitter 44.
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The engine oil pressure gauge, converter pressure, engine
temperature gauge and other vehicle functions are
connected via annunciator 55 to the microprocessor so that
these functions may be periodically checked. There is
also a "dump box down" sensor 56 operably connected to the
microprocessor for detecting whether the dump box is in
its down position. The transmission has high and low
forward and reverse gears and a neutral position and is
connected to the microprocessor which controls it.
. .
Forward wave form signal producing means is scanning laser
58. The laser is mounted so as to direct its signal 60
upwardly of the vehicle transversely of the direction of
travel of the truck. A first wave form sensor means 62
for detecting reflected laser signals is also provided.
The laser signal emitting and detecting devices of the
preferred embodiment are provided as a single unit in the
commercially available product "LASERNET", manufactured by
Namco Controls, Mentor, Ohio. Further details of the
device are described in U.S. Patent No. 4,788,441.~;
Rearward wave form si~nal producing means is provided by
scanning laser 64 mounted retractably on the underside of
dump box 66 of the truck and best seen in Figures 9-12.
As with the forwardly mounted laser, a laser signal sensor
2 0 a~ ~ 3 13
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means is provided by sensor 68 adjacent to the laser
signal emitting means and they form a unit. The rear
laser unit is shown in its concealed or fully retracted
position in Figures 6, 9 and 10. The laser 64 and
detector (i.e. sensor) 68 are protected from flying debris
by casing 70 and door 72 in its closed position hingedly
mounted to the casing at 74. The laser unit is connected
to mounting 76 by hinge 78 and is operably connected to
hydraulically drivan cylinder 80 which provides drive
means for movement between operable and retracted
positions of the unit. Sensor 82 detects whether the
laser is in its retracted position. Deployment of the
laser involves the opening of the door to the position
shown in Figure 12 and extension of cylinder arm 80 in the
direction of arrow 84 so as to rotate the laser into the
operating position of Figures 11 and 12. In its deployed,
that is operable position this laser scans its beam 84
(Figure 4~ upwardly of the vehicle transverse to the
direction of travel of the truck such that when the truck
is properly oriented with respect to the longitudinal
reference means the scanning beam will cross it
transversely.
An alternative deployment mechanism for the rear laser
unit is shown in Figures 24-27. A concealed i~e.l
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retracted position of the unit is shown in Figures 23-25
while a deployed or operable position is shown in Fiyures
22 and 27.
Laser 64, detector sensors 300, 310, are protected from
flying debris by casing 302, and housing 304 welded to the
underside of the dump box when in the closed position.
The laser unit 68, and casing 302 are mounted by means of
steel pins 306, sliding in tracks 308, and is operably
connected to hydraulically driven cylinder 311, which
provides drive means for movement between operable and
retracted positions of the unit. Sensor 300 detects
whether the laser is in the retracted position. Sensor
310 detects whether the laser is in the operable
position. In its operable position the laser sensor 68
scans its beam 84, (Figure 4) upwardly of the vehicle
transverse to the direction of the truck such that when
the truck is properly oriented with respect to the
longitudinal reference means, the scanning beam will cross
it transversely.
Mounted above the truck in drift 26 is coded longitudinal
reference means. In the preferred embodiment, this is
made up of guidance strip 86, code markers 88 and speed
markers 90. The strip and markers are retroreflective and
contain coded information described in more detail below.
The various references are mounted so as to be in the path
of the e~itted signal of the forward scanning laser beam
60 when the vehicle is travelling in the forward
direction. They are also mount:ed so as to be in the
scanning path of the emitted signal of the rearward
scanning laser 64 in its operating position when the
vehicle is travelling in the rearward direction.
'
The mechanical aspects of haulage trucks used in
underground mining environments are typically under
servomechanistic control and may therefore be responsively
connected to microprocessor means for direction by
electrical signals from the microprocessor. A number of
the vehicle operations are responsively connected to the
microprocessorO The microprocessor can direct: the
transmission to operate in its forward low gear, forward
high gear, reverse low gear, reserve high gear or neutral;
the dump box to raise and lower; the rear laser and sensor
unit to deploy from the concealed position; the rear laser
and sensor to retxact from the operating position; the
parking brake to be activated; the parking brake to be
released; light 92 to be turned on or off; the throttle to
occupy level :L, level 2 or level 3; the service brakes to
, . .
be activated or deactivated; the steering cylinder 94 to
extend and retract.
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The illustrated truck is articulated. It has front
portion provided by front bogey 96 pivotally connected to
rear portion, bogey 98 at connection 100. Extensible/
retractable steering cylinder 94 is connected at its ends
to the front and rear portions of the vehicle and is
offset to the left side of connection 100 as viewed in
Figure 3. Extension of the cylinder when the truck is
moving forwardly thus causes the truck to veer leftwardly
of its original path. Correspondingly, contraction of the
cylinder of a forwardly moving vehicle causes the truck to
veer rightwardly of its original path. Certain trucks are
equipped with pairs of steering cylinders, one cylinder on
each side of connection 100 and operate synchronously but
in opposite directions to each other
Turning to Figure 13, a portion of the longitudinal
reference of the preferred embodiment is more fully
illustrated. The components~ guidance strip 86 having
longitudinal axis 87, code marker 88, and speed ~arker 90
are retroreflective. That is, a ray of electromagnetic
radiation, such as a collimated light or laser ray is
reflected in a direction parallel to its incident
direction and along substantially the same path so that a
laser signal beamed from laser 58, for example, which hits
the retroreflective mat~rial will be bounced back to and
,
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thereby defected by the sensor 62 associated with that
laser. Such a laser and associated sensor are said to be
in a "retroreflective path" of the material. A
commercially available retroreflective material is
marketed by the 3M company under the trademark 2000X.
In practice one of the lasers emits a laser beam which
scans a path across the longitudinal reference and the
sensor of the same laser detects the portion of the beam
reflected by the retroreflective material. The laser
sensor has two output channels, the signal channel 101 and
the sync channel 103 as shown diagramatically in
Figure 15. The sync channel provides an internal gate
pulse and defines a 90 "window" portion of the scan
directed above the truck. The window of the laser of the
preferred embodiment is scanned in 12.5 milliseconds.
Preferably the reference is mounted such that it is
continuous, that is, it is mounted such that there is
always at least one component of the reference within
reflective range of a laser unit. It may be, however,
appropriate in certain locations for this not to be the
case. For example, a jagged protrusion in the mine roof
may make it difficult to install a guidance strip in a
particular location. In such an instance, the guidance
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strip would be missing from the location and ther~ would
be first and second portions of the strip leading up to
but not including the location. The microprocessor would
be programmed such that a truck travelling along the first
portion would continue to travel along its current course
for a predetermined distance until sensing the second
portion on the other side of the location. The truck
would be directed to stop if the second portion were not
sensed by the laser unit in the predetermined length of
time.
The signal channel provides a series of on/off pulses
within the window corresponding to changes in the
condition of the sensor. The pattern of reflected and
non-reflected light corresponds to the pattern of the
retroreflective material scanned by the beam. The pattern
is detected as a function of time and passed
electronically to the microprocessor which directs the
vehicle operations according to a predetermined set of
instructions associated with the pattern and the condition
of other input parameters, such as engine oil pressure,
dump box sensor, etc.
When properly operating the path of the scanning laser
beam crosses at least the guidance strip as indicated by
line 102 in Figure 13. It may scan up to five
,
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retroreflective items, the guidance strip and two code
markers, and two speed markers in a single pass as
indicated by line 104 in Figure 13. Each code marker 88
is made up of parallel rectangular segments, each segment
being composed of eight one-inch bars. Masking of a bar
with, for example, conventional masking tape substantially
eliminates the retroreflective property of the bar and
thus a laser beam scanning that bar will not be reflected
back to the sensor. The pattern of masked and unmasked
bars thus produces a bar code which may be "read" by the
scanning laser. The signal read during the scan
represented by line 105 in Figure 13 is thus represented
by the pattern shown in Figure 15. There is a total of
eight events, two due to the guidance strip and six from
the code marker.
In the illustrated embodiment, the first and last bars are
never masked while the central six bars are masked in one
of thirty-five possible combinations which produce 6
changes between a non-detecting and detecting condition of
the laser sensor, each change being referred to as an
"event". All such thirty-five bar codes are shown in
Figure 16.
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:
The distance travelled by the distal end of the laser beam
between a pair of events can be calculated from the
distance between the laser unit and the reference means,
the scan rate and the time between the events. This
calculated distance is referred to as the "distance
between events".
`,
The code markers provide sectors 106, each sector
providing one of the thirty-five possible bar codes. The
CPU is programmed to direct a particular combination of
vehicle operations in response to the code of each
sector. As previously stated, there are thirty-five
different bar codes which provide six events and thus the
CPU can be programmed to have up to thirty-five sets of
operating instructions to be followed in response to the
code markers alone.
The following chart links the number of events in a given
scan with the type of strips and markers scanned.
CHART I
Events Per Scan Type of Strip Present
a. <2 error
b. 2 guidance
c~ 4 guidanc~, speed; or
speed, guidance
d. 6 speed, guidance, speed
e. 8 guidance, code; or
- code, guidance
2~ 3~3
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Events Per Scan Type of_Strip Present
f. 10 guidance, speed, code; or
speed, guidance, code
g~ 12 speed, guidance, speed, code; or
code, speed, guidance, speed
h. 14 code, guidance, code
i. 16 code, speed, guidance, code; or
code, guidance, speed, code
Events Per Scan Type of Strip Present
j. 18 code, speed, guidance, speed,
code
k. >18 error
It is immediately known that some sort of error is present
in a scan if there are fewer than 2 events, more than 18
events, or an odd number of events, although, as
appropriate, the absence of a signal may be acceptable
under certain circumstances such as already discussed. If
there is an even number of events a predefined algorithm
is followed to determine whether the signal is
"legitimate". For example, if there are 2 events, the
distance between the events is determined to ensure that
the events are due to the guidance strip and not, for
example, to a speed marker, this result being caused by
the vehicle being slightly off course and the guidance
strip being out of the scanning zone or window of the
laser.
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Code markers and speed markers are arranged on either side
of the guidance strip as exempl:ified by the arrangement in
Figure 13. The guidance strip and markers on one side of
the guidance strip provide coded information to direct a
vehicle moving in one direction along the path while the
guidance strip and markers on the other side of the strip
are used to direct the vehicle moving in the other,
opposite direction along the path.
Information from the speed markers and code markers to the
right of the guidance strip, viewed in the direction of
vehicle travel as indicated by arrow 107 in Figure 13 are
used by the microprocessor to control the truck. For
example, if there are four events in a scan, the distance
betwean the first and second and third and fourth events
would be determined and the guidance strip, if present,
located. If the guidance strip is present the
microprocessor determines if situation (c) of Chart I has
occurred and goes on to determine if the speed marker is
to the left or right of the guidance strip. If it is to
the left, the speed marker is ignored and only the
location of the guidance strip within the window of the
scan used to direct the vehicle. If the speed marker is
to the right of the guidance strip, this information is
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used to determine vehicular speed as described below.
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Analogously, the microprocessor can determine whether anyof situations b-j has occu~red and then use the
information along with information from other sensors to
direct operations of the vehiclle under its control.
The speed markers which are similarly shaped to each other
are symmetrically tapered trapezoids, are always wider
than the guidance strip and are always narrower than the
code strips. Each marker i5 oriented such that each of
its tapered sides makes a substantially equal angle with
an axis 109 parallel to the longitudinal axis of the
guidance strip. Once a speed marker has been read in two
successive scans, the distance between its pair of events
in each scan and the time between each scan can be used,
given the shape of the marker, to calculate the speed of
the vehicle. It will be appreciated that the length of
each speed marker must be great enough such that a
travelling vehicle will scan the marker at least twice as
it passes by the marker.
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~` Once it is determined that the guidance strip has been
-~ detected in a scan, such as between the first and second
~ events 108, 110 shown in Figure 14, its location within
- the scan can be determined from the elapsed time between
the beginning of the high sync pulse 112 and the first
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ev~nt 108. The laser is mounted such that whPn the truck
is on level ground the 90 window projects upwardly and is
bisected by a longitudinal axis 113 of the truck bogey on
; which it is mounted as seen in ~Figure 17. The location of
the guidance strip with respect to the laser can thus be
determined from the location of the first event within the
scan. The location of the truck with respect to the
guidance strip can thus be determined and this information
used to steer the vehicle. If it is determined that the
truck is too far to the right of the guidance strip, the
steering cylinder is extended a predetermined amount to
cause the vehicle path to be corrected to the left. If it
- is determined that the truck is too far to the left of the
steering cylinder is contracted a predetermined amount to
cause the vehicle path to be corrected to the right. In
this way the control system serves to guide the vehicle
along the path determined by the layout of the guidance
strip.
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In a second preferred embodiment, the vehicle control
system is for use with a vehicle for travel along an
endless path. In this embodiment, a coded reference means
- is shown schematically in Figure 21 and includes guidance
strip 202 and one set of control markers 204 and speed
markers 206 located on one side of the guidance strip.
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There would be one scanning laser and associated sensor
mounted on the leading portion of a vehicle of this
embodiment, such as lasar 64 and sensor 68 on the forward
portion of the illustrated vehicle. This would be the
only leading portion in the second preferred embodiment.
OPE:RATION OF THE VEEIICLE
Typically, a vehicle is retrofitted with components of a
control system according to this invention so as to retain
its characteristics as a manually operated vehicle. The
control system components may be turned on or off using
switch 120.
To put the vehicle into automated operation it is manually
driven to a convenient starting point, for example
location 122 next to the stope. The vehicle would be
positioned so as to be appropriately located with respect
to the overhead guidance strip 86, as in Figure 3. The
vehicle control system would then be turned on.
When the control system is turned on, the parking brake
would be activated (if not already activated), and
light 92, which flashes to indicate the vehicle is being
operated by the control system is activated.
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Typically, the dump box would then be loaded with ore by
scoop tram 123. The scoop tram operatox would also set
the destination switch if there is one and confirm the
destination switch selection using the handheld infrared
transmitter 44. Automated movement of the vehicle would
then be initiated by use of the handheld infrared
transmitter 44.
The vehicle would then start off in its forward direction
along a predetermined path of the guidance strip 86.
Appropriate code markers 88 would be placed and the
microprocessor preprogrammed to direct various operations
of the vehicle as desired as it moves along the path.
One such operation is a brake check which is required in
certain mining operations before a truck moves onto a
downward grade having an incline greater than about 6. A
particular code marker which codes for the brake check
operation is mounted on the mine roof so that the scanning
laser will read the marker before the truck reaches the
slope. In response to detection of the marker by means of
the laser the preprogrammed microprocessor carries out the
steps of the brake check operation generally as follows:
1. Stop the truck by application of its service brakes,
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2~373
:: - 33 -
2. Place transmission in second gear;
3. Apply throttle for five seconds in forward;
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4. Reduce throttle and return transmission to neutral;
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If motion of the vehicle along the path has been detected,
for example, with reference to a tapered speed marker
during step 3 above indicating unsatisfactory performance
of the brakes applied in step 1 then an emergency stop
procedure is instituted. If the brakes perform
satisfactorily, then the brakes are released and travel is
: resumed.
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- It will be appreciated that a travelling vehicle at times
will be oriented, in the course of adjustment of its
-:,.
travel path, such that the scanning path of the laser is
at an angle which is not precisely orthogonal to the edge
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of the reference guide, as indicated by line 124 in
Figure 13.
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The effect of this is an increase in the distance between
~-~ events as read by the laser, the degree of increased
distance increasing with angle 125 shown in Figure 13. An
~ appropriate tolerance for variations of this sort is
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incorporated into the programme of the control system.
The angle 125 and thus the angle 127 of the bogey of the
vahicle on which the laser is mounted with respect to the
guidance strip in Figure 17 may be calculated from the
distance between events due to the edges of the guide.
This information may be used in the programme for steering
the vehicle.
Figure 18 illustrates a guidance strip which is forked at
zone 131. There is thus a plurality of paths along which
the guidance strip is located and along which the vehicle
may travel. The control system may thus be employed to
direct a "turn-around" operation of the vehicle, if this
is desired. With reference to Figure 18, a vehicle to the
left of turn-around zone 126, in response to detection of
code bar 128, would use only the right hand edge 130 (as
viewed from the leading portion of the vehicle) of the
guidance strip for guidance into the zone. In response to
code bar 132, the control system would stop the vehicle,
reverse the direction of the vehicle including
transmission direction. Whichever laser had b~en
scanning, that is reading, the reference means would be
deactivated and the other activated, and the corresponding
collision avoidance system deactivated and activated. The
vehicle would then be directed to move on, again following
the right hand edge 134 of the guidance strip as it
travels in the direction of arrow 136.
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The control system of this invention can also be used to
direct the operations of two vehicles working in the same
area by provision of a siding 138 illustrated in
Figure 19. Appropriately, a first vehicle travelling in
the direction of arrow 140, upon encountering code
bar 142, would be directed to follow the right hand
edge 144 of guidance strip 86 and thus be steered into the
siding. Code marker 143 would instruct the vehicle system
to stop the vehicle, and to broadcast a signal from
whichever infrared transmitter is on the leading portion
of the vehicle. A second vehicle travelling in the
direction of arrow 145, upon encountering code marker 146,
would stop and wait for receipt of an infrared signal via
the receiver on its leading portion from a vehicle in the
siding. The second vehicle would then proceed following
the right hand side 148 of the guidance strip for its path
of travel. Upon encountering code marker 150, the second
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vehicle transmits an infrared signal via the transmitter
on its leading portion. Upon encountering code marker 1~1
transmission of the infrared signal would be stopped.
Receipt of this signal by the first vehicle waiting in the
siding would serve as an instruction to the first vehicle
to proceed in its original direction of travel back onto
the main path of travel.
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Further, the strip and markers may be used as instructions
directing a vehicle, the leading edge of which is the dump
box portion, into the dump station 152 of Figure 20,
followed by appropriate halting of the vehicle, dumping of
the box load into box hole 32, and reversal of vehicle
operations to direct the truck back to the stope for
reloading.
Each collision avoidance system is continually monitored
when active to ensure that it is in proper operation.
Each test transponder is operably connected to the
microprocessor system. In operation, the test transponder
is activated and deactivated according to a regular timed
pattern. For example, it may be activated for alternating
ten millisecond intervals. Signals received in a
corresponding pattern by receiver antenna 51 indicates
that the system is properly operating and that no signals
are being received by other transponders such as those
mounted on the clothing of personnel. If the pattern of
signals received by the receiver antenna is disrupted for
any length of time, say one second, vehicle operations,
and particularly vehicle movement are immediately shut
down by the microprocessor in a predetermined fashion.
The control system may be reactivated once the source of
the disruption is removed, whether it be the presence of
another transponder or a malfunction of the collision
avoidance system.
