Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ADAPTIVE ACCELERATION FOR MATERIALS HANDLING VEHICLE
BACKGROUND ART
100011 Materials handling vehicles are commonly used
for picking stock in warehouses
and distribution centers. Such vehicles typically include a power unit and a
load handling
assembly, which may include load carrying forks. The vehicle also has control
structures for
controlling operation and movement of the vehicle.
100021 In a typical stock picking operation, an
operator fills orders from available stock
items that are located in storage areas provided along one or more aisles of a
warehouse or
distribution center. The operator drives the vehicle between various pick
locations where
item(s) are to be picked. The operator may drive the vehicle either by using
the control
structures on the vehicle, or via a wireless remote control device that is
associated with the
vehicle, such as the remote control device disclosed in commonly owned U.S.
Patent Na
9,082,293, the entire disclosure of which is hereby incorporated by reference
herein.
DISCLOSURE OF INVENTION
100031 In accordance with a first aspect of the
present invention, a method is provided for
operating a materials handling vehicle comprising: monitoring, by a
controller, a first vehicle
drive parameter corresponding to a first direction of travel of the vehicle
during a first manual
operation of the vehicle by an operator; concurrently monitoring, by the
controller, a second
vehicle drive parameter corresponding to a second direction different from the
first direction
of travel during the first manual operation of the vehicle by an operator,
receiving, by the
controller after the first manual operation of the vehicle, a request to
implement a first semi-
automated driving operation; and based on the first and second monitored
vehicle drive
parameters during the first manual operation, controlling, by the controller,
implementation of
the first semi-automated driving operation.
[0004] The first vehicle drive parameter may comprise
acceleration in the first direction
and the second vehicle drive parameter may comprise acceleration in the second
direction.
[00105] The first and second directions may be
substantially orthogonal to each other.
[0006] The method may further comprise: calculating a
first value indicative of
acceleration in the first direction; calculating a second value indicative of
acceleration in the
second direction; and modifying the first value based on the second value if
the second value
falls outside of a predefined mid-range. Based on the modified value,
implementation of the
first semi-automated driving operation may be controlled by the controller.
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100071 Controlling implementation of the first semi-
automated driving operation may
comprise limiting a maximum acceleration of the vehicle.
100081 In accordance with a second aspect of the
present invention, a method is provided
for operating a materials handling vehicle comprising: monitoring, by a
controller, a vehicle
drive parameter during a most recent manual operation of the vehicle by an
operator; replacing,
by the controller, any stored first data regarding the monitored vehicle drive
parameter
associated with a previous manual operation of the vehicle by the operator
with second data
regarding the monitored vehicle drive parameter during the most recent manual
operation of
the vehicle, the second data not being based on the first data; receiving, by
the controller, a
request to implement a semi-automated driving operation; and based on the
second data
regarding the monitored vehicle drive parameter corresponding to the most
recent manual
operation, controlling by the controller, implementation of the semi-automated
driving
operation.
100091 The second data may comprise sequential
individual values associated with the
vehicle drive parameter.
100101 The individual values may be grouped into a
plurality of subsets of values, each
subset comprising a same predetermined number of adjacent individual values;
and for each of
the plurality of subsets, calculating a respective aritlunelic or weighted
average associated with
that subset based at least in part on the individual values in that subset.
100111 The method may further comprise: selecting a
particular one of the respective
arithmetic or weighted averages; and based on the particular one of the
arithmetic or weighted
averages, controlling by the controller, implementation of the semi-automated
driving
operation.
100121 Wherein controlling implementation of the semi-
automated driving operation may
comprise limiting a maximum acceleration of the vehicle.
104:1131 The particular one weighted average may
comprise a maximum of the respective
arithmetic or weighted averages.
100141 In accordance with a third aspect of the
present invention, a system is provided for
operating a materials handling vehicle comprising: a memory storing executable
instructions;
a processor in communication with the memory, the processor when executing the
executable
instructions: monitors a first vehicle drive parameter corresponding to a
first direction of travel
of the vehicle during a first manual operation of the vehicle by an operator,
concurrently
monitors a second vehicle drive parameter corresponding to a second direction
different from
the first direction of travel during the first manual operation of the vehicle
by an operator;
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receives, after the first manual operation of the vehicle, a request to
implement a first semi-
automated driving operation; and controls implementation of the first semi-
automated driving
operation based on the first and second monitored vehicle drive parameters
during the first
manual operation.
[0015] The first vehicle drive parameter may comprise
acceleration in the first direction
and the second vehicle drive parameter may comprise acceleration in the second
direction.
[0016] The first and second directions may be
substantially orthogonal to each other.
[0017] The processor when executing the executable
instructions: may calculate a first
value indicative of acceleration in the first direction; may calculate a
second value indicative
of acceleration in the second direction; and may modify the first value based
on the second
value if the second value falls outside of a predefined mid-range.
[0018] The processor when executing the executable
instructions: may control
implementation of the first semi-automated driving operation based on the
modified value.
[0019] Controlling implementation of the first semi-
automated driving operation may
comprise limiting a maximum acceleration of the vehicle.
[0020] In accordance with a fourth aspect of the
present invention, a system is provided for
operating a materials handling vehicle comprising: a memory storing executable
instructions;
a processor in communication with the memory, the processor when executing the
executable
instructions: monitors a vehicle drive parameter during a most recent manual
operation of the
vehicle by an operator; replaces any stored first data regarding the monitored
vehicle drive
parameter associated with a previous manual operation of the vehicle by the
operator with
second data regarding the monitored vehicle drive parameter during the most
recent manual
operation of the vehicle, the second data not being based on the first data;
receives a request to
implement a semi-automated driving operation; and controls implementation of
the semi-
automated driving operation based on the second data regarding the monitored
vehicle drive
parameter corresponding to the most recent manual operation.
[0021] The second data may comprise sequential
individual values associated with the
vehicle drive parameter.
[0022] The processor when executing the executable
instructions: may group the
individual values into a plurality of subsets of values, each subset
comprising a same
predetermined number of adjacent individual values; and for each of the
plurality of subsets,
may calculate a respective arithmetic or weighted average associated with that
subset based at
least in part on the individual values in that subset.
[0023] The processor when executing the executable
instructions: may select a particular
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one of the respective arithmetic or weighted averages; and may control
implementation of the
semi-automated driving operation based on the particular one of the arithmetic
or weighted
averages.
[0024] Controlling implementation of the semi-
automated driving operation may comprise
limiting a maximum acceleration of the vehicle.
100251 The particular one arithmetic or weighted
average may comprise a maximum of the
respective arithmetic or weighted averages.
BRIEF DESCRIPTION OF DRAWINGS
[0026] Fig. 1 is an illustration of a materials
handling vehicle capable of remote wireless
operation according to various aspects of the present invention;
[0027] Fig 2 is a schematic diagram of several
components of a materials handling vehicle
capable of remote wireless operation according to various aspects of the
present invention;
[0028] Fig. 3 depicts a flowchart of an example
algorithm for monitoring first and second
drive parameters during a most recent manual operation of the vehicle and,
based on the first
and second drive parameters, controlling implementation of a semi-automated
driving
operation;
[0029] Fig 4 depicts a flowchart of an example
algorithm for calculating a first value
indicative of acceleration of the vehicle in a first direction during a most
recent manual
operation of the vehicle;
[0030] Fig. 5 illustrates a table containing non-real
sample acceleration values in the first
direction corresponding to a most recent manual operation of the vehicle;
[0031] Fig. 6 illustrates a table containing sample
values of wax- i;
[0032] Fig. 7 depicts a flowchart of an example
algorithm for calculating a second value
indicative of acceleration of the vehicle in a second direction during a most
recent manual
operation of the vehicle;
[0033] Fig. 8 illustrates a table containing non-
real sample acceleration values in the
second direction corresponding to a most recent manual operation of the
vehicle;
[0034] Fig. 9 illustrates a table containing sample
values of ay_ i;
[0035] Fig. 10 depicts a flowchart of an example
algorithm for calculating a maximum
acceleration to be used during a next semi-automated driving operation based
on the first and
second values indicative of acceleration of the vehicle in the first and
second directions during
the prior manual operation of the vehicle; and
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100361 Fig. 11 depicts a lookup table containing three
separate ranges for the maximum
acceleration in the second direction (ay- max).
BEST MODE FOR CARRYING OUT THE INVENTION
[0037] In the following detailed description of the
illustrated embodiments, reference is
made to the accompanying drawings that form a part hereof, and in which is
shown by way of
illustration, and not by way of limitation, specific embodiments in which the
invention may be
practiced. It is to be understood that other embodiments may be utilized and
that changes may
be made without departing from the spirit and scope of various embodiments of
the present
invention.
Low Level Order Picking Truck
100381 Referring now to the drawings, and particularly
to Fig. 1, a materials handling
vehicle, which is illustrated as a low level order picking truck 10, includes
in general a load
handling assembly 12 that extends from a power unit 14. The load handling
assembly 12
includes a pair of forks 16, each fork 16 having a load supporting wheel
assembly 18. The load
handling assembly 12 may include other load handling features in addition to,
or in lieu of the
illustrated arrangement of the forks 16, such as a load backrest, scissors-
type elevating forks,
outriggers or separate height adjustable forks. Still further, the load
handling assembly 12 may
include load handling features such as a mast, a load platform, collection
cage or other support
structure carried by the forks 16 or otherwise provided for handling a load
supported and
carried by the truck 10 or pushed or pulled by the truck, i.e., such as by a
tugger vehicle.
100391 The illustrated power unit 14 comprises a step-
through operator's station 30
dividing a first end section 14A of the power unit 14 (opposite the forks 16)
from a second end
section 14B (proximate the forks 16). The step-through operator's station 30
provides a
platform 32 upon which an operator may stand to drive the truck 10 and/or to
provide a position
from which the operator may operate the various included features of the truck
10.
100401 A first work area is provided towards the first
end section 14A of the power unit 14
and includes a control area 40 for driving the truck 10 when the operator is
standing on the
platform 32 and for controlling the features of the load handling assembly 12.
The first end
section 14A defines a compartment 48 for containing a battery, control
electronics, including
a controller 103 (see Fig. 2), and motor(s), such as a traction motor, steer
motor and lift motor
for the forks (not shown).
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100411 As shown for purposes of illustration, and not
by way of limitation, the control area
40 comprises a handle 52 for steering the truck 10, which may include controls
such as grips,
butterfly switches, thumbwheels, rocker switches, a hand wheel, a steering
tiller, etc., for
controlling the acceleration/braking and travel direction of the truck 10. For
example, as
shown, a control such as a switch grip 54 may be provided on the handle 52,
which is spring
biased to a center neutral position. Rotating the switch grip 54 forward and
upward will cause
the truck 10 to move forward, e.g., power unit first, at an acceleration
proportional to the
amount of rotation of the switch grip 54 until the truck 10 reaches a
predefined maximum
speed, at which point the truck 10 is no longer permitted to accelerate to a
higher speed. For
example, if the switch grip 54 is very quickly rotated 50% of a maximum angle
of rotation
capable for the grip 54, the truck 10 will accelerate at approximately 50% of
the maximum
acceleration capable for the truck until the truck reaches 50% of the maximum
speed capable
for the truck. It is also contemplated that acceleration may be determined
using an acceleration
map stored in memory where the rotation angle of the grip 54 is used as an
input into and has
a corresponding acceleration value in the acceleration map. The acceleration
values in the
acceleration map corresponding to the grip rotation angles may be proportional
to the grip
rotation angles or vary in any desired manner. There may also be a velocity
map stored in
memory where the rotation angle of the grip 54 is used as an input into and
has a corresponding
maximum velocity value stored in the velocity map. For example, when the grip
54 is rotated
50% of the maximum angle capable for the grip 54, the truck will accelerate at
a corresponding
acceleration value stored in the acceleration map to a maximum velocity value
stored in the
velocity map corresponding to the grip angle of 50% of the maximum angle.
Similarly,
rotating the switch grip 54 toward the rear and downward of the truck 10 will
cause the truck
to move in reverse, e.g., forks first, at an acceleration proportional to the
amount of rotation
of the switch grip 54 until the truck 10 reaches a predefined maximum speed,
at which point
the truck 10 is no longer permitted to accelerate to a higher speed.
100421 Presence sensors 58 may be provided to detect
the presence of an operator on the
truck 10. For example, presence sensors 58 may be located on, above or under
the platform
floor, or otherwise provided about the operator's station 30. In the exemplary
truck 10 of Fig
1, the presence sensors 58 are shown in dashed lines indicating that they are
positioned under
the platform floor. Under this arrangement, the presence sensors 58 may
comprise load
sensors, switches, etc. As an alternative, the presence sensors 58 may be
implemented above
the platform floor, such as by using ultrasonic, capacitive or other suitable
sensing technology.
The utilization of presence sensors 58 will be described in greater detail
herein.
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100431 An antenna 66 extends vertically from the power
unit 14 and is provided for
receiving control signals from a corresponding wireless remote control device
70. It is also
contemplated that the antenna 66 may be provided within the compartment 48 of
the power
unit 14 or elsewhere on the truck 10. The remote control device 70 may
comprise a transmitter
that is worn or otherwise maintained by the operator. The remote control
device 70 is manually
operable by an operator, e.g., by pressing a button or other control, to cause
the remote control
device 70 to wirelessly transmit at least a first type of signal designating a
travel request to the
truck 10. The travel request is a command that requests the corresponding
truck 10 to travel
by a predetermined amount, as will be described in greater detail herein.
[0044] The truck 10 also comprises one or more
obstacle sensors 76, which are provided
about the truck 10, e.g., towards the first end section of the power unit 14
and/or to the sides of
the power unit 14. The obstacle sensors 76 include at least one contactless
obstacle sensor on
the truck 10, and are operable to define at least one detection zone. For
exa.mple, at least one
detection zone may define an area at least partially in front of a forward
traveling direction of
the truck 10 when the truck 10 is traveling in response to a wirelessly
received travel request
from the remote control device 70.
[0045] The obstacle sensors 76 may comprise any
suitable proximity detection technology,
such as ultrasonic sensors, optical recognition devices, infrared sensors,
laser scanner sensors,
etc., which are capable of detecting the presence of objects/obstacles or are
capable of
generating signals that can be analyzed to detect the presence of
objects/obstacles within the
predefined detection zone(s) of the power unit 14.
[0046] In practice, the truck 10 may be implemented in
other formats, styles and features,
such as an end control pallet truck that includes a steering tiller arm that
is coupled to a tiller
handle for steering the truck. Similarly, although the remote control device
70 is illustrated as
a glove-like structure 70, numerous implementations of the remote control
device 70 may be
implemented, including for example, finger worn, lanyard or sash mounted, etc.
Still further,
the truck, remote control system and/or components thereof, including the
remote control
device 70, may comprise any additional and/or alternative features or
implementations,
examples of which are disclosed in any one or more of the following commonly
owned
patents/published patent applications: U.S. Provisional Patent Application
Serial No.
60/825,688, filed September 14, 2006 entitled "SYSTEMS AND METHODS OF
REMOTELY CONTROLLING A MATERIALS HANDLING VEHICLE;" U.S. Patent
Application Serial No. 11/855,310, filed September 14, 2007 entitled "SYSTEMS
AND
METHODS OF REMOTELY CONTROLLING A MATERIALS HANDLING VEHICLE;"
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U.S. Patent Application Serial No. 11/855,324, filed September 14, 2007
entitled "SYSTEMS
AND METHODS OF REMOTELY CONTROLLING A MATERIALS HANDLING
VEHICLE;" U.S. Provisional Patent Application Serial No. 61/222,632, filed
July 2, 2009,
entitled "APPARATUS FOR REMOTELY CONTROLLING A MATERIALS HANDLING
VEHICLE," U.S. Patent Application Serial No. 12/631,007, filed December 4,
2009, entitled
"MULTIPLE ZONE SENSING FOR MATERIALS HANDLING VEHICLES;" U.S.
Provisional Patent Application Serial No. 61/119,952, filed December 4, 2008,
entitled
"MULTIPLE ZONE SENSING FOR REMOTELY CONTROLLED MATERIALS
HANDLING VEHICLES;" and/or U.S. Patent No. 7,017,689, issued March 28, 2006,
entitled
"ELECTRICAL STEERING ASSIST FOR MATERIAL HANDLING VEHICLE;" the entire
disclosures of which are each hereby incorporated by reference herein.
Control System for Remote Operation of a Low Level Order Picking Truck
100471 Referring to Fig. 2, a block diagram
illustrates a control arrangement for integrating
remote control commands with the truck 10. The antenna 66 is coupled to a
receiver 102 for
receiving commands issued by the remote control device 70. The receiver 102
passes the
received control signals to the controller 103, which implements the
appropriate response to
the received commands and may thus also be referred to herein as a master
controller. In this
regard, the controller 103 is implemented in hardware and may also execute
software (including
firmware, resident software, micro-code, etc.). Furthermore, aspects of the
present invention
may take the form of a computer program product embodied in one or more
computer readable
medium(s) having computer readable program code embodied thereon.
100481 Thus, the controller 103 may comprise an
electronic controller defining, at least in
part, a data processing system suitable for storing and/or executing program
code and may
include at least one processor coupled directly or indirectly to memory
elements, e.g., through
a system bus or other suitable connection. The memory elements can include
local memory
employed during actual execution of the program code, memory that is
integrated into a
microcontroller or application specific integrated circuit (ASIC), a
programmable gate array or
other reconfigurable processing device, etc. The at least one processor may
include any
processing component operable to receive and execute executable instructions
(such as
program code from one or more memory elements). The at least one processor may
comprise
any kind of a device which receives input data, processes that data through
computer
instructions, and generates output data. Such a processor can be a
microcontroller, a hand-held
device, laptop or notebook computer, desktop computer, microcomputer, digital
signal
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processor (DSP), mainframe, server, cell phone, personal digital assistant,
other programmable
computer devices, or any combination thereof Such processors can also be
implemented using
programmable logic devices such as field programmable gate arrays (FPGAs) or,
alternatively,
realized as application specific integrated circuits (ASICs) or similar
devices. The term
"processor" is also intended to encompass a combination of two or more of the
above recited
devices, e.g., two or more microcontrollers.
100491 The response implemented by the controller 103
in response to wirelessly received
commands, e.g., via the wireless transmitter 70 and corresponding antennae 66
and receiver
102, may comprise one or more actions, or inactions, depending upon the logic
that is being
implemented. Positive actions may comprise controlling, adjusting or otherwise
affecting one
or more components of the truck 10. The controller 103 may also receive
information from
other inputs 104, e.g., from sources such as the presence sensors 58, the
obstacle sensors 76,
switches, load sensors, encoders and other devices/features available to the
truck 10 to
determine appropriate action in response to the received commands from the
remote control
device 70. The sensors 58, 76, etc. may be coupled to the controller 103 via
the inputs 104 or
via a suitable truck network, such as a control area network (CAN) bus 110.
100501 In one embodiment, the controller 103 may
comprise an accelerometer which may
measure physical acceleration of the truck 10 along three axes. It is also
contemplated that the
accelerometer 1103 may be separate from the controller 103 but coupled to and
in
communication with the controller 103 for generating and transmitting to the
controller 103
acceleration signals, see Fig. 2. For example, the accelerometer 1103 may
measure the
acceleration of the truck 10 in a direction of travel DT (also referred to
herein as a first direction
of travel) of the truck 10, which, in the Fig. 1 embodiment, is collinear with
an axis X. The
direction of travel DT or first direction of travel may be defined as the
direction in which the
truck 10 is moving, either in a forward or power unit first direction or a
reverse or forks first
direction. The accelerometer 1103 may further measure the acceleration of the
truck 10 along
a transverse direction TR (also referred to herein as a second direction)
generally 90 degrees to
the direction of travel DT of the truck 10, which transverse direction TR, in
the Fig. 1
embodiment, is collinear with an axis V. The accelerometer 1103 may also
measure the
acceleration of the truck 10 in a further direction transverse to both the
direction of travel DT
and the transverse direction TR, which further direction is generally
collinear with a Z axis.
100511 In an exemplary arrangement, the remote control
device 70 is operative to
wirelessly transmit a control signal that represents a first type signal such
as a travel command
to the receiver 102 on the truck 10. The travel command is also referred to
herein as a "travel
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signal", "travel request" or "go signal". The travel request is used to
initiate a request to the
truck 10 to travel by a predetermined amount, e.g., to cause the truck 10 to
advance or jog,
typically only in the power unit first direction, by a limited travel
distance. The limited travel
distance may be defined by an approximate travel distance, travel time or
other measure. In
one implementation, the truck may be driven continuously as long as an
operator provides a
travel request not lasting longer than a predetermined time amount, e.g., 20
seconds. After the
operator no longer provides a travel request or if the travel request has been
provided for more
than the predetermined time period, a traction motor effecting truck movement
is no longer
activated and the truck is permitted to coast to a stop. The truck 10 may be
controlled to travel
in a generally straight direction or along a previously determined heading.
100521 Thus, a first type signal received by the
receiver 102 is communicated to the
controller 103. If the controller 103 determines that the travel signal is a
valid travel signal and
that the current vehicle conditions are appropriate (explained in greater
detail below), the
controller 103 sends a signal to the appropriate control configuration of the
particular truck 10
to advance and then stop the truck 10. Stopping the truck 10 may be
implemented, for example,
by either allowing the truck 10 to coast to a stop or by initiating a brake
operation to cause the
truck 10 to brake to a stop.
100531 As an example, the controller 103 may be
communicably coupled to a traction
control system, illustrated as a traction motor controller 106 of the truck
10. The traction motor
controller 106 is coupled to a traction motor 107 that drives at least one
driven wheel 108 of
the truck 10. The controller 103 may communicate with the traction motor
controller 106 so
as to accelerate, decelerate, adjust and/or otherwise limit the speed of the
truck 10 in response
to receiving a travel request from the remote control device 70. The
controller 103 may also
be communicably coupled to a steer controller 112, which is coupled to a steer
motor 114 that
steers at least one steered wheel 108 of the truck 10. In this regard, the
truck 10 may be
controlled by the controller 103 to travel an intended path or maintain an
intended heading in
response to receiving a travel request from the remote control device 70.
100541 As yet another illustrative example, the
controller 103 may be communicably
coupled to a brake controller 116 that controls truck brakes 117 to
decelerate, stop or otherwise
control the speed of the truck 10 in response to receiving a travel request
from the remote
control device 70. Still further, the controller 103 may be communicably
coupled to other
vehicle features, such as main contactors 118, and/or other outputs 119
associated with the
truck 10, where applicable, to implement desired actions in response to
implementing remote
travel functionality.
to
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100551 According to various aspects of the present
invention, the controller 103 may
communicate with the receiver 102 and with the traction controller 106 to
operate the truck 10
under remote control in response to receiving travel commands from the
associated remote
control device 70.
100561 Correspondingly, if the truck 10 is moving in
response to a command received by
remote wireless control, the controller 103 may dynamically alter, control,
adjust or otherwise
affect the remote control operation, e.g., by stopping the truck 10, changing
the steer angle of
the truck 10, or taking other actions. Thus, the particular vehicle features,
the state/condition
of one or more vehicle features, vehicle environment, etc., may influence the
manner in which
the controller 103 responds to travel requests from the remote control device
70.
100571 The controller 103 may refuse to acknowledge a
received travel request depending
upon predetermined condition(s), e.g., that relate to environmental or
operational factor(s). For
example, the controller 103 may disregard an otherwise valid travel request
based upon
information obtained from one or more of the sensors 58, 76. As an
illustration, according to
various aspects of the present invention, the controller 103 may optionally
consider factors
such as whether an operator is on the truck 10 when determining whether to
respond to a travel
command from the remote control device 70. As noted above, the truck 10 may
comprise at
least one presence sensor 58 for detecting whether an operator is positioned
on the truck 10. In
this regard, the controller 103 may be further configured to respond to a
travel request to
operate the truck 10 under remote control when the presence sensor(s) 58
designate that no
operator is on the truck 10. Thus, in this implementation, the truck 10 cannot
be operated in
response to wireless commands from the transmitter unless the operator is
physically off of the
truck 10. Similarly, if the object sensors 76 detect that an object, including
the operator, is
adjacent and/or proximate to the truck 10, the controller 103 may refuse to
acknowledge a
travel request from the transmitter 70. Thus, in an exemplary implementation,
an operator must
be located within a limited range of the truck 10, e.g., close enough to the
truck 10 to be in
wireless communication range (which may be limited to set a maximum distance
of the
operator from the truck 10). Other arrangements may alternatively be
implemented.
100581 Any other number of reasonable conditions,
factors, parameters or other
considerations may also/alternatively be implemented by the controller 103 to
interpret and
take action in response to received signals from the transmitter. Other
exemplary factors are
set out in greater detail in any one or more of the following commonly owned
patents/published
patent applications: U.S. Provisional Patent Application Serial No.
60/825,688, entitled
"SYSTEMS AND METHODS OF REMOTELY CONTROLLING A MATERIALS
it
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HANDLING VEHICLE," U.S. Patent Application Serial No. 11/855,310, entitled
"SYSTEMS
AND METHODS OF REMOTELY CONTROLLING A MATERIALS HANDLING
VEHICLE;" U.S. Patent Application Serial No. 11/855,324, entitled "SYSTEMS AND
METHODS OF REMOTELY CONTROLLING A MATERIALS HANDLING VEHICLE,"
U.S. Provisional Patent Application Serial No. 61/222,632, entitled "APPARATUS
FOR
REMOTELY CONTROLLING A MATERIALS HANDLING VEHICLE;" US. Patent
Application Serial No. 12/631,007, entitled "MULTIPLE ZONE SENSING FOR
MATERIALS HANDLING VEHICLES," and U.S. Provisional Patent Application Serial
No.
61/119,952, entitled "MULTIPLE ZONE SENSING FOR REMOTELY CONTROLLED
MATERIALS HANDLING VEHICLES:" the disclosures of which are each already
incorporated by reference herein.
[0059] Upon acknowledgement of a travel request, the
controller 103 interacts with the
traction motor controller 106, e.g., directly or indirectly, e.g., via a bus
such as the CAN bus
110 if utilized, to advance the truck 10 by a limited amount. Depending upon
the particular
implementation, the controller 103 may interact with the traction motor
controller 106 and
optionally, the steer controller 112, to advance the truck 10 by a
predetermined distance.
Alternatively, the controller 103 may interact with the traction motor
controller 106 and
optionally, the steer controller 112, to advance the truck 10 for a period of
time in response to
the detection and maintained actuation of a travel control on the remote 70.
As yet another
illustrative example, the truck 10 may be configured to jog for as long as a
travel control signal
is received. Still further, the controller 103 may be configured to "time out"
and stop the travel
of the buck 10 based upon a predetermined event, such as exceeding a
predetermined time
period or travel distance regardless of the detection of maintained actuation
of a corresponding
control on the remote control device 70.
[0060] The remote control device 70 may also be
operative to transmit a second type signal,
such as a "stop signal", designating that the truck 10 should brake and/or
otherwise come to
rest. The second type signal may also be implied, e.g., after implementing a
"travel" command,
e.g., after the truck 10 has traveled a predetermined distance, traveled for a
predetermined time,
etc., under remote control in response to the travel command. If the
controller 103 determines
that a wirelessly received signal is a stop signal, the controller 103 sends a
signal to the traction
controller 106, the brake controller 116 and/or other truck component to bring
the truck 10 to
a rest. As an alternative to a stop signal, the second type signal may
comprise a "coast signal"
or a "controlled deceleration signal" designating that the truck 10 should
coast, eventually
slowing to rest.
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100611 The time that it takes to bring the truck 10 to
a complete rest may vary, depending
for example, upon the intended application, the environmental conditions, the
capabilities of
the particular truck 10, the load on the truck 10 and other similar factors.
For example, after
completing an appropriate jog movement, it may be desirable to allow the truck
10 to "coast"
some distance before coming to rest so that the truck 10 stops slowly. This
may be achieved
by utilizing regenerative braking to slow the truck 10 to a stop.
Alternatively, a braking
operation may be applied after a predetermined delay time to allow a
predetermined range of
additional travel to the truck 10 after the initiation of the stop operation.
It may also be desirable
to bring the truck 10 to a relatively quicker stop, e.g., if an object is
detected in the travel path
of the truck 10 or if an immediate stop is desired after a successful jog
operation. For example,
the controller may apply predetermined torque to the braking operation. Under
such
conditions, the controller 103 may instruct the brake controller 116 to apply
the brakes 117 to
stop the truck 10.
Calculating Vehicle Drive Parameter(s) for Use During Remote Control Operation
of
Vehicle
100621 As noted above, an operator may stand on the
platform 32 within the operator's
station 30 to manually operate the truck 10, i.e., operate the truck in a
manual mode. The
operator may steer the truck 10 via the handle 52 and, further, may cause the
truck 10 to
accelerate via rotation of the switch grip 54. As also noted above, rotation
of the switch grip
54 forward and upward will cause the truck 10 to move forward, e.g., power
unit first, at an
acceleration that may be proportional to the amount of rotation of the switch
grip 54. Similarly,
rotating the switch grip 54 toward the rear and downward of the truck 10 will
cause the truck
to move in reverse, e g., forks first, at an acceleration that may be
proportional to the amount
of rotation of the switch grip 54.
104631 As also noted above., the controller 103 may
communicate with the receiver 102 and
with the traction controller 106 to operate the truck 10 under remote control
in response to
receiving travel commands from the associated remote control device 70. The
travel request
is used to initiate a request to the truck 10 to travel by a predetermined
amount, e.g., to cause
the truck 10 to advance orjog in the first direction of travel, i.e., in the
power unit first direction,
by a limited travel distance. Hence, the operator may operate the truck 10 in
a remote control
mode when the operator is not physically present on the truck but is walking
near the truck 10
such as during a picking operation, Le., when the operator is located off the
truck 10 and picking
or gathering pick items from warehouse storage areas to be loaded on the truck
10. Operating
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the truck 10 in the remote control mode is also referred to herein as "semi-
automated" operation
of the truck 10.
[0064] When an operator is using the truck 10, such as
during a picking operation within a
warehouse, the operator typically uses the truck 10 in both the manual mode
and the remote
control mode.
[0065] Previously, a vehicle controller stored a
predefined, fixed vehicle parameter, e.g., a
maximum acceleration, to limit the maximum acceleration of the vehicle during
operation of
the vehicle in the remote control mode. This predefined maximum acceleration
limit was
sometimes too high, e.g., if the truck was being loaded with a tall stack of
articles/packages
defining loads that were unstable, and too low if the truck was being loaded
with a short stack
of articles/packages defining loads that were stable.
[0066] In accordance with the present invention, the
controller 103 monitors one or more
drive parameters during a most recent manual operation of the truck 10, which
one or more
drive parameters correspond to a driving behavior or trait of an operator of
the truck 10. If the
one or more drive parameters are high, this may correspond to the operator
driving the truck
briskly. If the one or more drive parameters are low, this may correspond to
the operator
driving the truck 10 conservatively or cautiously. Instead of using one or
more predefined,
fixed drive parameters for vehicle control during remote control operation of
the truck 10, the
present invention calculates one or more adaptive drive parameters for use by
the controller
103 during a next remote control operation of the truck 10 based on the one or
more drive
parameters monitored during a most recent manual operation of the truck 10.
Since the one or
more drive parameters calculated for use in the next remote control operation
of the truck 10
are based on recent driving behavior of the operator, i.e., the one or more
drive parameters
monitored during the most recent manual mode operation of the truck 10, it is
believed that the
present invention more accurately and appropriately defines the one or more
drive parameters
to be used during a next remote control operation of the truck 10 such that
the one or more
drive parameters more closely match to the most recent driving behavior of the
operator.
[0067] An example control algorithm, or process, for
the controller 103 is illustrated in Fig.
3 for monitoring first and second drive parameters, e.g., acceleration in
first and second
directions, during a most recent manual operation of the truck 10 to calculate
a corresponding
adaptive drive parameter, e.g., a maximum acceleration, to be used by the
controller 103 when
the truck 10 is next operated in the remote control mode.
[0068] In step 201, the controller 103 monitors
concurrently during a most recent manual
operation of the vehicle, a first drive parameter, e.g., a first acceleration,
corresponding to a
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first direction of travel of the vehicle or truck 10 arid a second drive
parameter, e.g., a second
acceleration, corresponding to a second direction, which is different from the
first direction of
travel. In the illustrated embodiment, the first direction of travel may be
defined by the
direction of travel DT of the truck 10, see Fig. 1, and the second direction
may be defined by
the transverse direction TR. Hence, the first and second directions may be
substantially
orthogonal to one another. The controller 103 replaces any stored data, i.e.,
first stored data,
regarding the monitored first and second vehicle drive parameters
corresponding to the
previous manual operation of the vehicle by the operator with recent data,
i.e., second data,
regarding the monitored first and second vehicle drive parameters during the
most recent
manual operation of the vehicle, wherein the recent data is not calculated
using or based on the
previously stored data from the previous manual operation of the vehicle. The
vehicle may
have been operated in a remote control mode after the previous manual
operation of the vehicle
and before the most recent manual operation of the vehicle.
[0069] An operator may vary acceleration of the truck
10 based on factors such as the
curvature of the path along which the truck 10 is being driven, the turning
angle of the truck
10, the current floor conditions, e.g., a wet/slippery floor surface or a
dry/non-slippery floor
surface, and/or the weight and height of any load being carried by the truck
10. For example,
if the truck 10 is being driven without a load or with a stable load, e.g.,
the load has a low
height, over a long, straight path, on a dry/non-slippery floor surface, then
values for the first
acceleration may be high. However, if the truck 10 has an unstable load, e.g.,
the load has a
high height, such that the load may shift or fall from the truck 10 if the
truck 10 is accelerated
quickly, then values for the first acceleration may be low. Also, if the truck
10 is being turned
at a sharp angle and driven at a high speed, then values for the first
acceleration may be high
and values for the second acceleration may also be high.
[0070] In step 203, the controller 103 receives, after
the most recent manual operation of
the vehicle or truck 10, a request to implement a semi-automated driving
operation, i.e., a
request to operate the truck 10 in the remote control mode. In the illustrated
embodiment and
as discussed above, the controller 103 may receive a travel request from the
remote control
device 70. Such a travel request may define a request to implement a first
semi-automated
driving operation.
[0071] In step 205, the controller 103, based on the
first and second monitored vehicle
drive parameters during the most recent manual operation of the truck 10,
implements the semi-
automated driving operation of the truck 10. The controller 103, based on the
recent data
regarding the monitored first and second vehicle drive parameters during the
most recent
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manual operation of the vehicle, calculates a first value indicative of
acceleration of the truck
in the first direction and a second value indicative of acceleration of the
truck 10 in the
second direction. The controller 103 modifies the first value indicative of
acceleration in the
first direction based on the second value indicative of acceleration in the
second direction if the
second value falls outside of a pre-defined range. The first value, whether
modified or not
based on whether the second value falls outside or within the pre-defined
range, defines a
maximum acceleration that cannot be exceeded during the semi-automated driving
operation
of the truck 10.
100721 An example control algorithm, or process, for
the controller 103 is illustrated in Fig.
4 for calculating a first value indicative of acceleration of the truck 10 in
the first direction
during the most recent manual operation of the truck 10. In step 301, a
sequence of positive
acceleration values in The first direction from the accelerometer 1103 are
collected during the
most recent manual operation of the vehicle, wherein the first direction is
defined by the
direction of travel DT of the truck 10, and stored in memory by the controller
103. Rotation of
the switch grip 54 forward and upward will cause the truck 10 to move forward,
e.g., power
unit first, at a positive acceleration in the power unit first direction
proportional to the amount
of rotation of the switch grip 54. Similarly, rotating the switch grip 54
toward the rear and
downward of the truck 10 will cause the truck 10 to move in reverse, e.g.,
forks first, at a
positive acceleration in the forks first direction proportional to the amount
of rotation of the
switch grip 54. As the truck 10 accelerates in either the power unit first
direction or the forks
first direction, both considered the first direction as defined by the
direction of travel DT of the
truck 10, the accelerometer 1103 generates a sequence of positive acceleration
values that are
stored in memory by the controller 103. Negative acceleration values, such as
occurring during
braking, are not collected for use in calculating the first value indicative
of acceleration of the
truck 10 in the first direction during the most recent manual operation of the
vehicle.
100731 In step 303, the acceleration values in the
first direction collected during the most
recent manual operation of the truck 10 are filtered with a weighted average
equation so as to
make maximum outliers less weighted and effect smoothing. Example equation 1,
set out
below, may be used to filter the collected acceleration values in the first
direction to calculate
weighted average values based on the collected acceleration values in the
first direction from
the most recent manual operation of the truck 10.
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Equation 1: Wax_(L+i) =
wax-i *91 ax_ronroi-11* 92 + ax_ftisirt)+2]* 93 + aX W*170-1-3] * 94
Ygs
W ax-a-F1) = calculated weighted average in a first direction (e.g., "x");
where i = 1 õ (n-1) and n is the total number of subsets into which the
individual collected
acceleration values, aa j, are grouped;
wax-i; where i = 1 õ .n; wax- i = arithmetic average of the first three
"starr acceleration values in the first direction for the first calculation
and thereafter the most
recent weighted average;
gs = weighting factor where s = 1... m+1, where m is the number of
members in each subset;
gi = weighting factor of wax_ i; in the illustrated embodiment, gi = 3, but
could be any value;
gz, gs, g4 = additional weighting factors = 1, but could be any value and
is typically less than gi;
ax_Risno+21, ax Risno+31, where i = 1... (n-1); ax
ax_Kism)+2], ax_1(0m)+31 = three adjacent individual acceleration values in
the first direction,
defining a subset, collected during the most recent manual operation of the
truck 10. The subset
could comprise more than three or less than three acceleration values. The
first three collected
acceleration values (ax_i, ax_2, and ax_3) make up a first subset as well.
100741 For purposes of illustration, sample
calculations will now be provided based on non-
real sample values, which simulate collected acceleration values in the first
direction, and are
set out in Table 1 of Fig, 5,
waxi = arithmetic average of the first three "start" acceleration values =
aX 2 + aX_3 1+2+4
__________________________________________________ = 2.33
in 3
91 * wax-i gz * ax 4 +9 * aX 5 +94 * aX 6
wag-2 = first weighted average value ¨
Egg
3*2.33 +1* 8 +14,3 +1*2
= 3.33
6
91 * Wax-2 + * ax7 + 93 * axa + 94 * alq
ax- 3= second weighted average value ¨
E.95
3* 3.33 +1 41 + 14,0 + 1*0
= 1.83
6
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[0075] The remaining weighted average values based on
the sample values set out in Table
1 of Fig. 5 are calculated in a similar manner. The results are set out in
Table 2 of Fig. 6.
[0076] Thus, with respect to Equation 1, the values
ax_Rrin) Fib ax_Fosnoni, and ax_Rrim-01 are
used in the calculation of a weighted average value wax_( +1). According to
the example of
Fig. 5, "i" can range from 1 to 9, but for purposes of Equation 1, "i" ranges
from Ito 8.
Accordingly, the 27 acceleration values (i.e., ax `1" = 27 individual
collected acceleration
values in the Example of Fig. 5) in the table of Fig. 5 can be arranged as 9
distinct subsets each
having 3 elements. Other than the first subset, which, as noted above,
comprise an arithmetic
average of the first three "start" acceleration values in the first direction,
for each of the
subsequent 8 subsets, a weighted average is calculated according to Equation
1. The example
initial arithmetic average and the example 8 weighted averages are shown in
Fig. 6. One of
ordinary skill will readily recognize that the subset size of 3 values is
merely an example and
that utilizing 9 subsets is an example amount as well.
[0077] In step 305 of Fig. 4, a maximum acceleration
in the first direction defined by the
direction of travel DT of the truck 10 is determined using example Equation 2,
set out below:
Equation 2: ax_wa_max = maximum acceleration in the first direction =
max(wax_O = maximum value of the initial arithmetic and weighted averages (wax-
i)
calculated
[0078] Based on the results from Table 2 of Fig. 6,
max(wax_ ) = s = 3.82.
[0079] It is noted that ax-wa-max may be selected from
any number of initial arithmetic and
weighted average values (wax_ 0 calculated. For example, the average values
(wax- 0
calculated during a predetermined time period, e.g., the last ten seconds, may
be considered. It
is also contemplated that a predetermined number of initial arithmetic and
weighted average
values (wax_ 0 calculated, e.g., 25 average values, without taking time into
account, may be
considered. It is further contemplated that all of the initial arithmetic and
weighted average
values (wax- 0 calculated during the entirety of the most recent manual
operation of the truck
may be considered. In the illustrated example, nine (9) values of initial
arithmetic and
weighted averages (w, ) were considered. However, less than 9 or greater than
9 values of
initial arithmetic and weighted averages (wax- i) can be considered when
selecting max(ax-wa-
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0 = maximum value of the initial arithmetic and weighted averages (wax_ 0
calculated, which
defines the ax-wa-max= maximum acceleration in the first direction. The
maximum acceleration
in the first direction (ax-wa-max) defines the first value indicative of
acceleration of the vehicle
in the first direction during the most recent manual operation of the vehicle.
Instead of selecting
the maximum or highest value from the set of initial arithmetic and weighted
average values
(wax- 0 considered as the maximum acceleration in the first direction ax-wa-
max, it is
contemplated that a second or a third highest value of the initial arithmetic
and weighted
average values (wax- ) considered may be selected as the maximum acceleration
in the first
direction ax_wa_max. It is further contemplated that the set of initial
arithmetic and weighted
average values (wax_ 0 considered may be averaged to determine the maximum
acceleration in
the first direction ax-wa-max,
100801 An example control algorithm, or process, for
the controller 103 is illustrated in Fig.
7 for calculating a second value indicative of acceleration of the truck 10 in
the second direction
during the most recent manual operation of the truck 10. In step 401, a
sequence of acceleration
values in the second direction from the accelerometer 1103 are collected,
wherein the second
direction is defined by the transverse direction TR, see Fig. 1, and stored in
memory by the
controller 103.
100811 In step 403, the collected acceleration values
in the second direction collected
during the most recent manual operation of the truck 10 are filtered with a
weighted average
equation so as to make maximum outliers less weighted and effect smoothing.
Example
equation 3, set out below, may be used to filter the collected acceleration
values in the second
direction from the most recent manual operation of the truck 10.
Equation 3: way_ (j +1) =
way_i *91. + ay Kinri)+1]* 92 + ay_K(*m)+2] * 93 + ay_Ris170+ 3] * 94
Way- (j+1) = calculated weighted average in a second direction (e.g., "y");
where i = 1 ..(n-1);
way- i; where i = 1 n; way_ = arithmetic average of the first three
"start" acceleration values in the second direction for the first calculation
and thereafter the
most recently calculated weighted average;
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gs = weighting factor where s = 1... m+1, where in is the number of
members in each subset;
gi = weighting factor of way-i; in the illustrated embodiment, gi = 3, but
could be any value;
g2, g3, gs = additional weighting factors = I, but could be other values;
ay_Reno-Fil, ay_yeno+21, ayi(i*m)+3]; where i = 1 ... (n-1); ay_Remp 11,
ay_Kom)+21, ay_ki+m)+31= three adjacent individual acceleration values in the
second direction,
defining a subset, collected during the most recent manual operation of the
truck 10. The subset
could comprise more than three or less than three acceleration values. The
first three collected
acceleration values (ay_i, ay_2, and ay_3) make up a first subset as well.
100821 For purposes of illustration, sample
calculations will now be provided based on non-
real sample values, which simulate collected acceleration values in the second
direction, and
are set out in Table 3 of Fig. S.
way- i = arithmetic average of the first three "start" acceleration values in
the second
a i+a 2+a 3 0.25 + 0.49 + 0.52
direction = 37- __ 7- = =
0.42
in 3
Way_i * gi + ayji. * g2 + ay_s* g3 + ay 6 *94
Way- 2 = first weighted average value
_______________________________________________________________________________
_
ps
3* 0.42 + 1* 0.54 + 1 * 0.75 + 1 * 0.72
¨ 0.55
6
100831 The remaining weighted average value based on
the sample values set out in Table
3 of Fig. 8 is calculated in a similar manner. The results are set out in
Table 4 of Fig. 9.
100841 hi step 405 of Fig. 7, a maximum acceleration
in the second direction defined by
the transverse direction TR of the truck 10 is determined using Equation 4,
set out below:
Equation 4: ay-wa-max = maximum acceleration in the second direction
= max(way_ = maximum value of the initial arithmetic and weighted averages
(way- 0
calculated.
[0085] Based on the results from Table 4 of Fig. 9,
max(way- = way-2= 0.55.
100861 It is noted that ay-wa-max may be selected from
the initial arithmetic average or any
number of weighted averages (way-0+10 calculated. For example, the initial
arithmetic and
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weighted average values (way_ 0 calculated during a predetermined time period,
e.g., the last
ten seconds, may be considered. It is also contemplated that a predetermined
number of the
initial arithmetic and weighted average values (way_ ) calculated, e.g., 25
average values,
without taking time into account, may be considered. It is further
contemplated that all of the
initial arithmetic and weighted average values (way-0 calculated during the
entirety of the most
recent manual operation of the truck 10 may be considered. In the illustrated
example, three
(3) values of the initial arithmetic and weighted averages (way-') were
considered. However,
less than 3 or greater than 3 values of the initial arithmetic and weighted
averages (way- 0 can
be considered when selecting max(way_ = maximum value of the initial
arithmetic and
weighted averages (way_ ) calculated, which defines the ay-wa-max= maximum
acceleration in
the second direction. The maximum acceleration of the vehicle in the second
direction (ay-wa-
max) defines the second value indicative of acceleration of the vehicle in the
second direction
during the most recent manual operation of the vehicle.
100871 An example control algorithm, or process, for
the controller 103 is illustrated in Fig.
for calculating a maximum acceleration to be used during a next semi-automated
driving
operation based on the first and second values indicative of acceleration of
the truck 10 in the
first and second directions during the prior or most recent manual operation
of the truck 10.
As noted above, the first value indicative of acceleration of the truck 10 in
the first direction is
defined by the maximum acceleration in the first direction (ax-wa-max) and the
second value
indicative of acceleration of the truck 10 in the second direction is defined
by the maximum
acceleration in the second direction (ay--). During operation of the truck 10,
an operator
may drive the truck 10 quickly along a generally straight path, but slowly
during a turn. To
factor in the operator driving the truck 10 slowly during a turn, in step 501,
the controller 103
compares the maximum acceleration in the second direction (ay-wa-max) to
empirically
determined ranges set out in a lookup table stored in memory to determine if a
correction to the
maximum acceleration in the first direction (ax-wa-max) is appropriate.
100881 As explained in detail below, the maximum
acceleration in the second direction (ay-
wa-max) can be used to correct, or adjust, the calculated maximum acceleration
in the first
direction ax-waimax when determining the maximum acceleration for the next
semi-automated
driving operation. The maximum acceleration in the second direction (ay-wa-
max) is likely
indicative of the operator's evaluation of the stability of the truck 10 and
its current load. If
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the maximum acceleration in the second direction is greater than a first
empirically derived
value or within an empirically derived `high acceleration" range, then that
can indicate the
operator believes the load is relatively stable and the maximum acceleration
for the next semi-
automated driving operation can be increased. However, if the maximum
acceleration in the
second direction is less than a second empirically derived value or falls
within an empirically
defined "low acceleration" range, then that can indicate the operator believes
the load could be
unstable even though the calculated maximum acceleration in the first
direction is relatively
high. Thus, in this second instance, the maximum acceleration for the next
semi-automated
driving operation can be decreased. If the maximum acceleration in the second
direction is in-
between the first and the second empirically derived values or within an
empirically defined
medium range, then no correction, or adjustment, of the maximum acceleration
for the next
semi-automated driving operation is made. High, low and medium ranges (or
empirically
derived first and second values) can be empirically determined for a
particular vehicle in a
controlled environment where the vehicle is operated at various maximum
accelerations in the
first and second directions, various high, low and medium ranges of differing
values are created
and, using the maximum acceleration values in the second direction, correction
factors are
determined and used to adjust the maximum acceleration values in the first
direction. Preferred
high, low and medium ranges, which allow for an optimum acceleration in the
first direction
yet allow the truck to carry and support loads in a stable manner are
selected.
[0089] An exemplary simulated lookup table based on
non-real values is set out in Fig. 11,
which table contains three separate ranges for the maximum acceleration in the
second
direction (ay,a_max). If the maximum acceleration in the second direction
falls within either
the high or the low acceleration range depicted in the lookup table of Fig.
11, a corresponding
correction factor is used in determining the maximum acceleration to be used
during the next
semi-automated driving operation of the truck 10. If the maximum acceleration
in the second
direction falls within the middle acceleration range (or mid-range) depicted
in the lookup table
of Fig. 11, no correction factor corresponding to the maximum acceleration in
the second
direction is used in determining the maximum acceleration for use during the
next semi-
automated driving operation of the truck 10.
[0090] In the example discussed above, the maximum
acceleration in the second direction
(ay--max) = 0.55. This value falls within the high acceleration range, which
corresponds to a
correction factor of +10%.
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100911 In step 503, the maximum acceleration to be
used during a next semi-automated
driving operation (which may also be referred to as "a semi-automated driving
operation
maximum acceleration") is calculated using example Equation 5:
Equation 5: max.acc = max(wax.i)* (1 + COffx COffy)
Where max.acc = the maximum acceleration to be used in the first
direction during a next semi-automated driving operation;
corrx = a safety margin, which could be equal to any value. In the
illustrated embodiment COffx = - 5% (may comprise a negative value as in the
illustrated
embodiment to reduce max.acc to provide a safety margin);
cony = correction factor from the lookup table in Fig. 11 and is based on
the maximum acceleration in the second direction (ay-wa-max).
[0092] A sample calculation for maxacc based on the
sample values discussed above will
now be provided.
max.acc = max(wax- * (1 + corrx + cony) = 3.82 * (1 - 0.05 + 0.1) =
4.01
[0093] Hence, in this example, the controller 103
communicates with the traction motor
controller 106 so as to limit the maximum acceleration of the truck 10 in the
first direction
during a next semi-automated or remote control operation to 4.01 rrits2.
[0094] It is also contemplated that the controller 103
may calculate a first value indicative
of deceleration of the vehicle in the first direction during the most recent
manual operation of
the vehicle using equations 1 and 2 set out above, wherein the absolute value
of each
deceleration value collected from the most recent manual operation of the
vehicle is used in
calculating the first value using equations 1 and 2. Deceleration values
corresponding to
emergency breaking, which deceleration values may have very high magnitudes,
are ignored
in calculating the first value indicative of deceleration of the vehicle.
[0095] In the event that the truck 10 does not have an
accelerometer, acceleration values in
the first and second directions can be calculated in alternative manners. For
example,
acceleration in the direction of travel DT or first direction can be
determined using a velocity
sensor, wherein a velocity sensor may be provided on a traction motor
controller. The
controller 103 may differentiate the velocity or speed values to calculate
acceleration values.
Acceleration may also be derived from the angular position of the switch grip
54 relative to a
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PCT/US2020/044262
home position, which grip 54, as noted above, controls the
acceleration/braking of the truck
10. Using the angular position of the grip 54 as an input into a lookup table,
a truck acceleration
is chosen from the lookup table which corresponds specific grip angular
position values with
specific acceleration values. Maximum velocity values may also be provided by
the lookup
table based on grip angular positions.
100961 Acceleration in the transverse direction TR or
second direction can be determined
using the following equation: acceleration y =
where v = truck speed; and
r = radius of a curve through which the truck moves;
The radius r may be calculated using the following equation:
r = wheelbase dimension/sin a
Where the wheelbase dimension is a fixed value and is equal to the distance
from the
front wheels to the rear wheels of the truck 10; and
Steering angle a, which is typically known by the controller 103 as it is the
steered
wheel angle.
100971 Having thus described the invention of the present application in
detail and by reference
to embodiments thereof, it will be apparent that modifications and variations
are possible
without departing from the scope of the invention defined in the appended
claims.
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