Note: Descriptions are shown in the official language in which they were submitted.
CA 02946013 2016-10-21
WORK PLATFORM WITH PROTECTION AGAINST SUSTAINED
INVOLUNTARY OPERATION
TECHNICAL FIELD
[0001] The invention relates to work platforms and, more particularly, to
a
work platform including an obstruction sensing system to reduce the
possibility of
collision with an obstruction or structure.
BACKGROUND OF THE INVENTION
[0002] Lift vehicles including aerial work platforms, telehandlers such as
rough terrain telescoping fork trucks with work platform attachments, and
truck
mounted aerial lifts are known and typically include an extendible flexible
configuration boom, which may be positioned at different angles relative to
the
ground, and a work platform at an end of the boom. On or adjacent the
platform,
there is typically provided a control console including various control
elements
that may be manipulated by the operator to control such functions as boom
angle,
boom extension, rotation of the boom and/or platform on a vertical axis,
engine or
other type of power source, and where the lift vehicle is of the self-
propelled type,
there are also provided steering, drive speed and direction and braking
controls.
[0003] A safety hazard can occur in a lift vehicle including a work
platform
when an operator is positioned between the platform and a structure that may
be
located overhead or behind the operator, among other places. Collision
avoidance
is also desirable with objects around the platform for example glass surfaces,
aircraft structures, and other more fragile or delicate structures.
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BRIEF SUMMARY OF THE INVENTION
[0004] A camera sensor or the like may be mounted to the aerial work platform
to
observe the platform, the area around the platform, and the operator. The
system
processes data from the sensor to determine whether the operator is present
and if
the operator is in a proper operating position and also to determine the
proximity
of objects above, behind and to the sides of and below the platform. Based on
data
from the sensor, a control module permits, modifies or prevents operation
and/or
manipulation of the platform.
[0005] In an exemplary embodiment, a work platform is combined with a system
for detecting obstacles. The work platform includes a control panel with
operating
components that control a position of the platform. The combined work platform
and system include a sensor mounted in a vicinity of the platform that is
configured to monitor at least one of an operator area, the platform, and an
area
around the platform, and a processor receiving a signal from the sensor that
processes the signal to determine at least one of a position of an operator on
the
platform and a proximity of objects in the area around the platform. A control
module communicating with the processor and the operating components modifies
control signals from the control panel based on communication with the
processor.
[0006] The processor may determine that the operator is not present or is not
in a
proper operating position, and the control module may be programmed to prevent
operation of the platform indicated by the operating components that would
cause
motion of the platform. An override switch may be connected with the control
module, where the control module may be programmed to permit operation of the
platform at very slow or creep speed based on activation of the override
switch.
The processor may determine that the operator is leaning over the control
panel,
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and the control module may be programmed to stop active functions and prevent
further operation of the platform that would cause motion of the platform. The
processor may determine that the operator is leaning over the control panel
for a
predetermined time, and the control module may be programmed to reverse a last
operating function of the platform. The processor may determine that the
operator
is present and in a proper operating position and that there are no objects in
the
area around the platform, and the control module may be programmed to permit
normal operation of the platform.
100071 In one embodiment, the sensor may be programmed to distinguish the area
around the platform between a warning zone and a danger zone, where the danger
zone is closer to the platform than the warning zone. The processor may
determine that an object is present in the warning zone, and the control
module
may be programmed to permit operation of the platform at creep speed based on
the determination that the object is present in the warning zone. The
processor
may determine that an object is present in the danger zone, and the control
module
may be programmed to prevent operation of the platform based on the
determination that the object is present in the danger zone. The sensor may be
programmed to adjust a depth of at least one of the warning zone and the
danger
zone based on operating characteristics of the platform. Exemplary operating
characteristics may include a number of operators on the platform, a direction
in
which the platform is traveling, and a speed of the platform. The control
module
may detect a speed of the platform, wherein the processor is programmed to
process signals from the sensor relating to the platform speed toward one of
the
objects in the area of the platform. In this context, the control module may
be
programmed to slow active functions at a rate relative to the speed at which
the
platform is approaching the one of the objects in the area of the platform.
The
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control module may be programmed to reduce a commanded operation speed
based on a proximity to one of the objects in the area of the platform.
[0008] The sensor may include multiple sensing elements secured in the
vicinity of
the platform. In one arrangement, the platform may include a platform railing,
where the sensor is mounted on the platform railing. The sensor may be one of
an
optical sensor, a radar sensor, and an acoustic sensor. The sensor may be
attached
to a manipulation device such as a pan and/or tilt mechanism or a mirror that
displaces or rotates the sensor field of view.
[0009] In another exemplary embodiment, an aerial work platform includes a
control panel including operator controls for manipulating the platform, a
control
module communicating with the operator controls and controlling manipulation
of
the platform based on signals from the control panel, and an obstruction
sensing
system. The obstruction sensing system includes a sensor mounted in a vicinity
of
the platform that is configured to monitor an operator area, the platform, and
an
area around the platform, and a processor receiving a signal from the sensor
that
processes the signal to determine a position of an operator on the platform
and a
proximity of objects in the area around the platform. The control module is in
communication with the processor and is programmed to modify control signals
from the operator controls based on communication with the processor.
[0010] In yet another exemplary embodiment, a method of controlling an aerial
work platform includes the steps of (a) monitoring with a sensor mounted in a
vicinity of the platform an operator area, the platform, and an area around
the
platform; (b) detecting with a processor receiving a signal from the sensor a
position of an operator on the platform and a proximity of objects in the area
around the platform; and (c) a control module modifying control signals from
an
operator control panel based on communication with the processor and based on
the detection in step (b). Step (c) may be practiced by preventing operation
of the
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platform when an operator is not present or is not in a proper operating
position.
Step (b) may be practiced to determine whether the operator is leaning over a
control panel for a predetermined period of time, and step (c) may be
practiced by
preventing operation of the platform during the predetermined period of time
and
after the predetermined period of time, reversing a last operating function of
the
platform. Step (c) may be practiced by permitting operation of the platform at
creep speed when an object is detected in the warning zone, and by preventing
operation of the platform when an object is detected in the danger zone.
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CA 02946013 2016-10-21
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] These and other aspects and advantages will be described in detail
with reference to the accompanying drawings, in which:
[0012] FIG. 1 shows an exemplary aerial lift vehicle including a work
platform;
[0013] FIG. 2 is a perspective view of the work platform and obstruction
sensing system according to preferred embodiments of the invention;
[0014] FIGS. 3-16 show the platfolin and the non-adaptive and adaptive
areas monitored by the sensor; and
[0015] FIGS. 17-21 show an exemplary pan/tilt mechanism and
functionality for the sensor unit.
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DETAILED DESCRIPTION OF THE INVENTION
[0016] FIG. 1 illustrates an exemplary typical aerial lift vehicle
including a
vehicle chassis 2 supported on vehicle wheels 4. Although the vehicle shown
includes a telescoping boom, the invention is equally applicable to other
vehicles
including, for example, articulated booms without telescoping or extendable
booms. A turntable and counterweight 6 are secured for rotation on the chassis
2,
and an extendible (flexible arrangement) boom assembly is pivotably attached
at
one end to the turntable 6. An aerial work platform 10 is attached at an
opposite
end of the extendible boom 8. The illustrated lift vehicle is of the self-
propelled
type and thus also includes a driving/control system (illustrated
schematically in
FIG. 1 at 12) and a control console 14 on the platform 10 with various control
elements that may be manipulated by the operator to control such functions as
boom angle, boom extension, rotation of the boom and/or platform on a vertical
axis, and engine, steering, drive speed and direction and braking controls,
etc.
[0017] FIG. 2 shows the combined work platform 10 and system 20 for
detecting obstructions such as obstacles around the platform including
overhead
obstacles. A sensor 22 is mounted in a vicinity of the platform and monitors
at
least one of an operator area, the platform, and an area around the platform.
The
sensor 22 may be a stereo camera sensor that provides a data stream consisting
of
pixel data (RGB value and range) to a computer or processor 24 mounted on the
platform 10. An exemplary stereo camera sensor is MultiSense S21 available
from Carnegie Robotics. Those of ordinary skill in the art will appreciate
alternative sensors that may be suitable, and the invention is not meant to be
limited to a specific sensor type.
[0018] The obstruction sensing system 20 may include multiple sensors 22
that are cooperable together and mounted in various areas in the vicinity of
the
platform 10. In an exemplary construction, the platform 10 includes a platform
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railing, and the sensor 22 is mounted on the platform railing. Mounting on the
platform provides for a static view of the platform through the full range of
boom
articulation. Sensors may alternatively or additionally be mounted to boom
structure to allow for a larger field of view of the platform and/or mounted
to
platform support structure other than the railing. For example, as shown, the
sensor 22 may be mounted on a dedicated bracket 23 secured to the platform, or
the sensor 22 may be secured adjacent the control panel 14.
[0019] The computer or processor 24 processes the pixel range data to
determine at least one of a position of an operator on the platform 10 and a
proximity of objects in the area around the platform 10. A control module 26
in
the control panel 14 forms part of the driving/control system 12 and
communicates
with the processor 24 to control operation of the platform based on a signal
from
the processor 24. In some arrangements, the control module 26 communicates
with the driving/control system 12, which controls overall operation of the
machine. In this arrangement, the control module 26 may gather input from
control devices such as joysticks, switches, etc. and communicate operator
commands to the driving/control system 12.
[0020] In some embodiments, the processor 24 determines whether the
operator is not present or is not in a proper operating position, and if so,
the
control module 26 is programmed to prevent operation of the platform 10. That
is,
if the operator is not detected, the computer 24 sends a data message to the
control
module 26 that prevents motion or operation, or stops all active functions of
the
work platfomi 10. The system may also include an override button 28, where the
platform 10 may be operated at creep speed if the override button 28 is
activated.
[0021] The processor 24 may determine that the operator is leaning over
the
control panel 14, in which case, the control module 26 is programmed to
prevent
operation of the platform 10. If the processor 24 determines that the operator
is
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leaning over the control panel for a predetermined time, the control module 26
is
programmed to reverse a last operating function of the platform. In this
instance,
the system may also sound an alarm and turn on a warning beacon.
[0022] Indicator lamps 29 may be secured to the platform railing and
around the control panel to communicate system status to the operator.
Exemplary
locations for the indicator lamps 29 are shown in FIG. 2. The control module
26
may cause the indicator lamps 29 to illuminate when the control module 26 is
in
any way affecting machine control.(e.g., when the sensors 22 indicate that the
machine is getting too close to an obstacle).
[0023] FIGS. 3-8 show exemplary sensing areas for detecting the proximity
of objects above, behind, below and to the sides of the platform 10. The
sensor 22
is programmed to distinguish the area around the platform between a warning
zone
(Zone A) 30 and a danger zone (Zones B and C) 32, where the danger zone 32 is
closer to the platform 10 than the warning zone 30 as shown. If the processor
24
determines that an object is present in the warning zone, the control module
26 is
programmed to permit operation of the platform 10 at creep speed. If the
processor 24 determines that an object is present in the danger zone 32, the
control
module 26 is programmed to prevent operation of the platform 10 (i.e., stop
all
active functions and/or prevent the start or continuation of any operation).
At any
time when the control module 26 prevents operation of the platform 10 that
would
cause motion of the platform 10, activation of the override switch 28 will
permit
operation of the platform 10 at creep speed. If the processor 24 determines
that
the operator is present and in a proper operating position and that there are
no
objects in the area around the platform 10 (i.e., in proximity defined by
proscribed
zones), the control module 26 permits normal, unrestricted operation of the
platfolin 10. If no operator is present, operation of the platform that would
cause
motion of the platform is prevented unless overridden with the override switch
28.
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[0024] Because the processor 24 is interpreting shape and distance from an
obstacle in real time, the processor 24 can be programmed to estimate
direction
and speed of movement of the platform in relation to recognized obstacles. The
processor 24 can be programmed to take action even when those obstacles are
outside of the warning zone 30. For example, the processor 24 can be
programmed to signal the driving/control system 12 to slow down machine
functions such as drive when the processor 24 recognizes that the operator is
driving the machine at full speed in the direction of potential obstacle. As
another
example, the boom functions (or drive function) can be slowed down more
aggressively if the processor determines that the machine is moving fast
toward a
collision point.
[0025] With reference to FIGS. 5-8, the warning zone 30 and the danger
zone 32 may be configured as adaptive zones, where based on the picture of the
surrounding environment, the control module 26 can adjust the size and shape
of
the respective zones 30, 32. Adaptive zones are calculated by the control
module
based on sensor system/controller ability to recognize, among other things,
the
number of people in the platform, or the combination of people and materials
(tools, equipment) present in the platform. FIGS. 7 and 8 illustrate results
of the
controller module calculation. In FIGS. 5 and 6, the zones 30, 32 are adapted
according to a specific operator. In FIG. 7, the zones 30, 32 are adapted
according
to the presence of two operators, and in FIG. 8, the zones are adapted
according to
an operator and equipment on the platform.
[0026] Various methods may be used for reducing the platform speed based
on detected object distance. In a "speed limiting" method, a limit for the
maximum commandable speed is set based on the distance to the detected object
(see, e.g., FIGS. 5-13). In a "speed reducing" method, the operator input is
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down based on the distance to the detected obstacle (see, e.g., FIGS. 14-16).
These two methods may result in different machine behavior.
[0027] The zones may be adapted to speed and direction of machine
movement. Zones can be adjusted to become deeper if it is determined that the
machine is moving faster than a threshold speed, or the zones can be "deeper'
in
the main direction of travel when activating the swing or other direction
function.
The control module may adjust the sensors to penetrate deeper into the
direction of
the side of platform. FIGS. 9-13 show variations in a depth of the warning
zone
and/or the danger zone based on platform speed and direction. More
specifically,
FIG. 9 shows the platform traveling to the right with each of the right side
warning
zone and danger zone having an increased depth. FIG. 10 shows the platform
descending with the warning and/or danger zones having an increased depth in
the
direction of platform movement. The system may be programmed to adjust the
depth of the zones based on the speed of the platform. FIGS. 11-13 show a
proportionally increased depth with increasing platform speed.
[0028] In a related context, the adaptive zones may incorporate
proportional
speed reduction zones as shown in FIGS. 14-16. In FIG. 14, the percent of
commanded speed is reduced according to the proximity of the potential
obstacle
to the platform. The speed reduction zones are shown in discrete steps but may
alternatively be continuous. In FIG. 15, the proportional speed reduction
zones
are combined with the zones adapted for speed and direction. In FIG. 15, the
platform is traveling to the right, and the depth of the zones is modified
accordingly. In FIG. 16, an object is detected in the 60% zone with the
platform
traveling to the right. The function speed is reduced to 60% of the commanded
speed.
[0029] Communication between the sensor 22 and the processor 24 may be
via digital packets (CANbus) or discrete signaling (digital or analog output).
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Other forms of digital communication may be used, allowing the sensor to
provide
information needed to evaluate environmental awareness. Examples include,
without limitation, Ethernet, I2C, RS232/485, digital pulse width modulation
(PWM), etc. The control module 26 interprets the data to determine if and how
the machine should react to the sensor data. The processor 24 based on signals
from the sensors 22 can determine if they need to be cleaned via a built-in
test
(BIT). The sensing elements 22 can be based on optical, radar or acoustic
(ultrasonic) sensing. The sensing elements 22 can be a single device or
multiple
devices with the same or complementary technologies. This provides redundancy
and tolerance to a range of environmental conditions, contamination on the
sensors, and objects to be detected. Sensors may be passive (stereo camera,
single
camera) or active (light detection and ranging (LiDAR), laser detection and
ranging (LADAR), 3D vision sensor), radar or acoustic (ultrasonic). Any
suitable
type of sensor(s) may be used, and the invention is not meant to be limited to
the
described exemplary embodiments. Alternative sensor arrangements that achieve
the same functionality are also contemplated including, for example, sensors
that
react to an emitter (via electromagnetic waves or other signals), reflective
tape (on
the machine and/or incorporated into the operator's protective gear), etc.
10030] With reference to FIGS. 17-21, the sensor 22 (camera, LiDAR,
RADAR, etc.) can be manipulated either by mechanical rotation (pan/tilt) of
the
entire sensor using a suitable pan/tilt mechanism 34 (an exemplary pan/tilt
mechanism is the Multisense S21 available from Carnegie Robotics), or by
mechanical displacement/rotation of the field of view via a polygon reflector
36,
single reflector 38, pair of reflectors 40 (optical mirror(s) for camera and
LiDAR,
metal plate(s) for radar and acoustic), etc. The manipulation device can be
controlled either by the processor 24, control module 26, sensor 22, or be
self-
contained in the manipulation device. Manipulating a sensor or sensor field of
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view allows each sensor to cover more of the surrounding area around the
platform and/or boom structure.
[0031] The platform and obstruction sensing system endeavor to avoid
collisions between the moving platform and obstacles in the vicinity of the
platform. The proactive system according to preferred embodiments is
advantageous as compared to reactive systems that make adjustments after an
obstacle has made contact with the operator and/or platform structure.
[0032] While the invention has been described in connection with what is
presently considered to be the most practical and preferred embodiments, it is
to
be understood that the invention is not to be limited to the disclosed
embodiments,
but on the contrary, is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the appended claims.
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