Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Based on Detected Start of Picking Operation, Resetting Stored Data Related to
Monitored Drive Parameter
BACKGROUND ART
[0001]
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.
[0002]
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.
DISCLOSURE OF INVENTION
[0003]
This disclosure relates to a method for operating a materials handling
vehicle that
includes monitoring, by a controller, a first vehicle drive parameter during a
manual operation
of the vehicle by an operator; storing, by the controller, data related to the
monitored first
vehicle drive parameter, the controller configured to use the stored data for
implementing a
semi-automated driving operation of the vehicle subsequent to the manual
operation of the
vehicle; detecting, by the controller, operation of the vehicle indicative of
a start of a pick
operation occurring during the manual operation of the vehicle; and based on
detecting the start
of the pick operation, resetting, by the controller, the stored data related
to the monitored first
vehicle drive parameter.
100041
The method in accordance with embodiments disclosed herein further includes
resuming, by the controller, monitoring of the first vehicle drive parameter
after resetting the
stored data.
[0005]
In accordance with embodiments disclosed herein, the detected operation of
the
vehicle comprises a transition from the vehicle being manually driven with a
raised load
handling assembly to the vehicle being stopped with a lowered load handling
assembly.
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Furthermore, the raised load handling assembly can be bearing a substantially
non-zero load
and the lowered load handling assembly can be bearing a substantially zero
load.
[0006]
In accordance with embodiments disclosed herein, the load handling assembly
can
comprise one or more forks and the detected operation of the vehicle further
comprises
movement of the vehicle for a distance, which distance may be at least equal
to a length of a
load carried by the forks. In particular, the movement of the vehicle for the
distance at least
equal to the length of the load carried by the forks occurs after the
transition of the vehicle to
being stopped with the lowered load handling assembly.
[0007]
In accordance with either of the above-mentioned embodiments, the detected
operation of the vehicle further comprises driving of the vehicle with a
lowered load handling
assembly. In particular, the lowered load handling assembly can be bearing a
substantially
zero load.
100081
In accordance with embodiments disclosed herein, the detected operation of
the
vehicle further comprises a transition from the vehicle moving with the
lowered load handling
assembly to the vehicle being stopped with a subsequently raised load handling
assembly,
wherein the subsequently raised load handling assembly bears a load less than
a predetermined
amount but more than the substantially zero load. For example, such a load
less than a
predetermined amount but more than the substantially zero load may comprise a
substantially
empty pallet on the load handling assembly.
[0009]
In accordance with embodiments disclosed herein, the detected operation of
the
vehicle comprises a first transition from the vehicle being manually driven
with a raised load
handling assembly to the vehicle being stopped with a lowered load handling
assembly;
movement of the vehicle with the lowered load handling assembly for a distance
at least equal
to a length of a load carried by the load handling assembly, the movement
occurring after the
first transition; and a second transition from the vehicle moving with the
lowered load handling
assembly to the vehicle being stopped with the load handling assembly newly
raised. In
particular, during the second transition the lowered load handling assembly
bears a
substantially zero load and the newly raised load handling assembly bears a
load less than a
predetermined amount but more than the substantially zero.
100101
In accordance with embodiments disclosed herein, the method can include
monitoring, by the controller, a second vehicle drive parameter during the
manual operation of
the vehicle by the operator; and storing, by the controller, data related to
the monitored second
vehicle drive parameter, the controller configured to use the stored data of
the monitored first
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and the second vehicle drive parameter for implementing the semi-automated
driving operation
of the vehicle subsequent to the manual operation of the vehicle.
[0011]
In accordance with embodiments disclosed herein, a system for operating a
materials handling vehicle includes a memory storing executable instructions;
and a processor
in communication with the memory. In particular, execution of the executable
instructions by
the processor causes the processor to: monitor a first vehicle drive parameter
during a manual
operation of the vehicle by an operator; store data related to the monitored
first vehicle drive
parameter, the controller configured to use the stored data for implementing a
semi-automated
driving operation of the vehicle subsequent to the manual operation of the
vehicle; detect
operation of the vehicle indicative of a start of a pick operation occurring
during the manual
operation of the vehicle; and reset the stored data related to the monitored
first vehicle drive
parameter based on detecting the start of the pick operation.
100121
The system further includes the processor resuming monitoring of the first
vehicle
drive parameter after resetting the stored data.
[0013]
In accordance with embodiments disclosed herein, the detected operation of
the
vehicle comprises a transition from the vehicle being manually driven with a
raised load
handling assembly to the vehicle being stopped with a lowered load handling
assembly.
Furthermore, the raised load handling assembly can be bearing a substantially
non-zero load
and the lowered load handling assembly can be bearing a substantially zero
load.
[0014]
In accordance with embodiments disclosed herein, the load handling assembly
can
comprise one or more forks and the detected operation of the vehicle further
comprises
movement of the vehicle for a distance, which distance may be at least equal
to a length of a
load carried by the forks. In particular, the movement of the vehicle for the
distance at least
equal to the length of the load carried by the forks occurs after the
transition of the vehicle to
being stopped with the lowered load handling assembly.
100151
In accordance with embodiments disclosed herein, the detected operation of
the
vehicle further comprises driving of the vehicle with a lowered load handling
assembly. In
particular, the lowered load handling assembly can be bearing a substantially
zero load.
[0016]
In accordance with embodiments disclosed herein, the detected operation of
the
vehicle further comprises a transition from the vehicle moving with the
lowered load handling
assembly to the vehicle being stopped with a subsequently raised load handling
assembly,
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wherein the subsequently raised load handling assembly bears a load less than
a predetermined
amount but more than the substantially zero load.
[0017]
In accordance with embodiments disclosed herein, the detected operation of
the
vehicle comprises a first transition from the vehicle being manually driven
with a raised load
handling assembly to the vehicle being stopped with a lowered load handling
assembly;
movement of the vehicle with the lowered load handling assembly for a distance
at least equal
to a length of a load carried by the load handling assembly, the movement
occurring after the
first transition; and a second transition from the vehicle moving with the
lowered load handling
assembly to the vehicle being stopped with the load handling assembly newly
raised. In
particular, during the second transition the lowered load handling assembly
bears a
substantially zero load and the newly raised load handling assembly bears a
load less than a
predetermined amount but more than the substantially zero load.
100181
In accordance with embodiments disclosed herein, the system can include the
processor monitoring a second vehicle drive parameter during the manual
operation of the
vehicle by the operator; and storing data related to the monitored second
vehicle drive
parameter, wherein the processor is configured to use the stored data of the
monitored first and
the second vehicle drive parameter for implementing the semi-automated driving
operation of
the vehicle subsequent to the manual operation of the vehicle.
BRIEF DESCRIPTION OF DRAWINGS
[0019]
Figs. 1A and 1B are illustrations of a materials handling vehicle capable
of remote
wireless operation according to one or more embodiments shown and described
herein;
[0020]
Fig. 2 is a schematic diagram of several components of a materials handling
vehicle
capable of remote wireless operation according to one or more embodiments
shown and
described herein;
100211
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 according to one or more embodiments shown and described herein;
100221
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 according to one or more embodiments shown and
described herein;
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[0023]
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
according to one or
more embodiments shown and described herein;
[0024]
Fig. 6 illustrates a table containing sample values of wax_ i according to
one or more
embodiments shown and described herein;
[0025]
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 according to one or more embodiments shown and
described herein;
[0026]
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 according to
one or more embodiments shown and described herein;
[0027]
Fig. 9 illustrates a table containing sample values of way_ i according to
one or more
embodiments shown and described herein;
[0028]
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 according to one or more embodiments
shown and
described herein;
[0029]
Fig. 11 depicts a lookup table containing three separate ranges for the
maximum
acceleration in the second direction (aywa-m) according to one or more
embodiments shown
and described herein;
[0030]
Fig. 12 depicts a flowchart of an example algorithm for resetting stored
data related
to the monitored first vehicle drive parameter based on detecting the start of
the pick operation,
according to one or more embodiments shown and described herein; and
[0031]
Fig. 13 ¨ Fig. 15 depict a sequence of vehicle operations indicative of the
start of a
pick operation during a manual operation of the vehicle according to one or
more embodiments
shown and described herein.
BEST MODE FOR CARRYING OUT THE INVENTION
[0032]
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 that may be
practiced. It is to
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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 this disclosure.
Low Level Order Picking Truck
[0033]
Referring now to the drawings, and particularly to Figs. 1A and 1B, 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.
[0034]
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.
[0035]
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).
100361
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, see
Figs. lA and 1B.
For example, as shown, a control such as a switch grip or travel switch 54 may
be provided on
the handle 52, which is spring biased to a center neutral position. Rotating
the travel switch 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 travel switch 54
until the truck 10
reaches a predefined maximum speed, at which point the truck 10 is no longer
permitted to
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accelerate to a higher speed. For example, if the travel switch 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 travel switch 54 toward the rear and
downward of the
truck 10 will cause the truck 10 to move in reverse, e.g., forks first, at an
acceleration
proportional to the amount of rotation of the travel switch 54 until the truck
10 reaches a
predefined maximum speed corresponding to the amount of rotation of the travel
switch 54, at
which point the truck 10 is no longer permitted to accelerate to a higher
speed.
[0037]
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, laser scanner,
camera or other
suitable sensing technology. The utilization of presence sensors 58 will be
described in greater
detail herein.
[0038]
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. According to one embodiment, the truck
10 may include
a pole (not shown) that extends vertically from the power unit 14 and includes
an antenna 66
that is provided for receiving control signals from a corresponding wireless
remote control
device 70. The pole may include a light at the top, such that the pole and
light define a light
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tower. 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.
[0039]
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
example, 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.
[0040]
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.
[0041]
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.
Control System for Remote Operation of a Low Level Order Picking Truck
[0042]
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,
embodiments may take
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the form of a computer program product embodied in one or more computer
readable
medium(s) having computer readable program code embodied thereon.
[0043]
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
processor (D SP), 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.
[0044]
The response implemented by the controller 103 in response to wirelessly
received
commands, e.g., via the wireless transmitter of the remote control device 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.
[0045]
A further input into the controller 103 may be a weight signal generated by
a load
sensor LS, such as a conventional pressure transducer, see Fig. 2, which
senses the combined
weight of the forks 16 and any load on the forks 16. The load sensor LS may be
incorporated
into a hydraulic system for effecting lift of the forks 16. By subtracting the
weight of the forks
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16 (a known constant value) from the combined weight of the forks 16 and a
load L on the
forks 16, which combined weight is defined by the weight signal from the load
sensor LS, the
controller 103 determines the weight of the load L on the forks 16.
Alternatively, in place of
the pressure transducer LS incorporated into the hydraulic system, one or more
weight sensing
cells (not shown) may be integrated into the forks 16 to sense a load L on the
forks 16 and
generate a corresponding load sensing signal to the controller 103.
[0046]
The controller 103 is also capable of determining the vertical location,
i.e., height,
of the load handling assembly 12 including the forks 16 relative to ground,
such as a floor
surface along which the truck 10 travels, as follows. One or more height
sensors or switches
may be provided in the second end section 14B of the power unit 14, which
sense when the
load handling assembly 12 including the forks 16 is raised vertically relative
to ground and/or
a lower point on the first end section 14A of the power unit 14. For example,
first, second and
third switches (not shown) may be provided within the second end section 14B
at first, second
and third vertical locations designated by dotted lines 141A, 141B and 141C in
Fig. 1A, which
switches are actuated as the load handling assembly 12 is raised. A lowermost
position of the
load handling assembly 12 may also be determined via the load sensor LS
indicating a zero
weight.
[0047]
In one embodiment, the controller 103 may comprise one or more
accelerometers
which may measure physical acceleration of the truck 10 along one, two or
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, which X axis may be generally parallel with the forks 16. 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 Y. 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 an axis Z.
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[0048]
In an exemplay 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
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.
[0049]
Thus, a first type signal received by the receiver 102 is communicated to
the
controller 101 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.
[0050]
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, wherein the steered
wheel may be different
from the driven wheel. 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.
[0051]
The controller 103 may determine whether the truck 10 is moving or stopped
and a
linear distance that the truck 10 has travelled as follows. First, the
controller 103 may
determine whether the truck 10 is moving or stopped using the signals
generated by the
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accelerometer 1103 and integrating once. It is also possible to determine if
the truck 10 is
moving by determining if the current value from the accelerometer 1103 is
greater than zero.
The controller 103 may also determine the linear distance that the truck 10
has travelled using
the signals generated by the accelerometer 1103 and integrating twice.
Alternatively, the
traction controller 106 may receive feedback signals generated by an encoder
within the
traction motor 107 and from those signals generate a motor angular velocity
signal to the
controller 103. The controller 103 may determine whether the vehicle is moving
or stopped
from the motor angular velocity signal. The controller 103 may also convert
the motor angular
velocity signal to an actual linear speed of the truck 10. If, for example,
the velocity signal
comprises an angular speed of the traction motor 107, then the controller 103
may scale that
value to an actual linear speed of the vehicle 10 based on a) a gearing ratio
between the traction
motor 107 and a driven wheel of the vehicle and b) the circumference of the
driven wheel. The
linear speed of the vehicle may then be used (via integration) to determine a
distance that the
truck 10 has travelled.
[0052]
As yet another illustrative example, the controller 103 may al so
communicate with
the traction controller 106 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.
Braking may be
effected by the traction controller 106 by causing regenerative braking or
activating a
mechanical brake 117 coupled to the traction motor 107, see Fig. 2. 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.
[0053]
According to embodiments, 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.
100541
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
controller 103 responds to travel requests from the remote control device 70.
[0055]
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
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information obtained from one or more of the sensors 58, 76. As an
illustration, according to
embodiments, 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 designates 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.
[0056]
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.
[0057]
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
control device 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 truck 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.
[0058]
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,
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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 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.
[0059]
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 traction controller 106
to brake via
regenerative braking or applying the mechanical brake 117 to stop the truck
10.
Calculating Vehicle Drive Pararneter(s) for Use During Remote Control
Operation of
Vehicle
[0060]
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, see Fig. 1B, and, further,
may cause the truck
to accelerate via rotation of the travel switch 54. As also noted above,
rotation of the travel
switch 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
travel switch 54.
Similarly, rotating the travel switch 54 toward the rear and downward of the
truck 10 will cause
the truck 10 to move in reverse, e.g., forks first, at an acceleration that
may be proportional to
the amount of rotation of the travel switch 54. Rotation of the travel switch
54 forward and
upward while the truck 10 is moving in the forks first direction will cause
the truck 10 to brake.
Also, rotating the travel switch 54 toward the rear and downward while the
truck 10 is moving
in the power unit first direction will cause the truck 10 to brake. Hence,
"manual operation of
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the vehicle by an operator" occurs when an operator is standing on the
platform 32 within the
operator's station 30 and steering the truck 10 via the handle 52 and
accelerating/braking (i.e.,
regenerative braking) the truck via rotation of the travel switch 54. A
separate brake switch,
for example switch 41 of Fig. 1B, can be used by the operator to cause
regenerative braking of
the truck 10. As noted above, braking may also be effected via the mechanical
brake 117.
[0061]
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 or jog 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, i.e., 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, using the
remote control device 70 to operate the truck 10 under remote control.
Operating the truck 10
in the remote control mode is also referred to herein as -semi-automated"
operation of the truck
10.
[0062]
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.
[0063]
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.
[0064]
In accordance with embodiments of the present disclosure, 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 10 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 controller 103 calculates one or more adaptive drive parameters
for use during a
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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
controller 103
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.
[0065]
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.
[0066]
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
first direction of travel of the vehicle or truck 10 and 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.
[0067]
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
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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.
[0068]
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.
[0069]
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
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.
[0070]
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 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 travel switch
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 travel switch 54. Similarly, rotating the travel switch 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
travel switch 54. As
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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. Rotation of the travel switch 54 forward and
upward while the
truck 10 is moving in the forks first direction will cause the truck 10 to
decelerate or brake.
Also, rotating the travel switch 54 toward the rear and downward while the
truck 10 is moving
in the power unit first direction will cause the truck 10 to decelerate or
brake. In accordance
with a first embodiment, 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.
[0071]
While rotation of the travel switch 54 forward and upward will cause the
truck 10
to move forward, i.e., power unit first, at a positive acceleration (speed is
increasing) in the
power unit first direction, the accelerometer may determine that such movement
comprises a
positive acceleration. The accelerometer may also determine that braking
(speed is
decreasing), while the truck 10 is traveling in the power unit first
direction, comprises
deceleration or negative acceleration. Further, while rotating the travel
switch 54 toward the
rear and downward will cause the truck 10 to move in reverse, e.g., forks
first, at a positive
acceleration (speed is increasing) in the forks first direction, the
accelerometer may determine
that such movement where the speed is increasing in the forks first direction
comprises a
negative acceleration. The accelerometer may also determine that braking
(speed is
decreasing) while the truck 10 is traveling in the forks first direction
comprises a positive
acceleration. However, for purposes of the discussion herein of a control
algorithm for
calculating a maximum acceleration to be used during a next semi-automated
driving operation,
acceleration and deceleration during movement of the truck 10 in the power
unit first direction
and the forks first direction will be defined as follows: rotation of the
travel switch 54 forward
and upward causing the truck 10 to move forward, e.g., power unit first, is
defined as a positive
acceleration (speed is increasing) in the power unit first direction; rotating
the travel switch 54
toward the rear and downward causing the truck 10 to move in reverse, e.g.,
forks first, is
defined as a positive acceleration (speed is increasing) in the forks first
direction; rotation of
the travel switch 54 forward and upward or actuating the brake switch 41 while
the truck 10 is
moving in the forks first direction causing the truck 10 to decelerate or
brake (speed is
decreasing) is defined as a negative acceleration or deceleration; and
rotation of the travel
switch 54 toward the rear and downward or actuation of the brake switch 41
while the truck 10
is moving in the power unit first direction causing the truck 10 to decelerate
or brake (speed is
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decreasing) is defined as a negative acceleration or deceleration.
[0072]
As noted above, in accordance with a first embodiment, negative
acceleration
values, such as occurring during braking in either the power unit first
direction or the forks first
direction, 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. However,
in accordance with a second embodiment, both positive acceleration values
(where the speed
of the truck is increasing in either the power unit first or the forks first
direction) and negative
acceleration values (where the speed of the truck is decreasing in either the
power unit first or
the forks first direction) are collected and used 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. In the second embodiment where negative acceleration values are
collected, the
absolute value of the negative acceleration values are used in the described
equations and
calculations set out below. Accordingly, while some embodiments may ignore any
negative
acceleration data, other embodiments can consider such data by using the
absolute value of the
negative acceleration data in the described equations and calculations,
[0073]
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.
Equation 1: wax_(I +1) =
wax-i * 91 + ax_[(i*in)+1] * 92 + ax_[(t*,70+2] * 93 + ax_[(t*no-F3] *94
wax-(i 11) = calculated weighted average in a first direction (e.g., "x");
where i = 1 ... (n-1) and n is the total number of subsets into which the
individual collected
acceleration values, ax _i, are grouped;
wax-i; where i = 1 ...n; wag- i = arithmetic average of the first three
-start" acceleration values in the first direction for the first calculation
and thereafter the most
recent weighted average;
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gs = weighting factor where s = 1... m+1, where m is the number of
members in each subset;
gi = weighting factor of wa,i; in the illustrated embodiment, gi = 3, but
could be any value;
g2, g3, g = additional weighting factors = 1, but could be any value and
is typically less than gi;
ax_[(i*m)+1], ax_Ri*m)+21, ax_Rem)+31, where i = 1... (n-1); ax_[(i*m)+1],
ax Ri*m)+2j, ax Ri*H0+3] = three adjacent individual acceleration values in
the first direction,
defining a subset, collected during the most recent manual operation of the
truck 1(). 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.
[0074]
The first "start" acceleration values in the first direction could comprise
less than
three or more than three values and the number of members in each subset "m"
could likewise
comprise less than three or more than three members.
[0075]
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. All of the acceleration values set out in
Table 1 are positive
values. However, as noted above, negative acceleration values could be
collected and used as
well. As further noted above, where negative acceleration values are
collected, the absolute
value of the negative acceleration values are used in the described equations
and calculations
set out herein.
wax i = arithmetic average of the first three "start" acceleration values =
ax_, + ax_2 + ax_3 = 1 2 4
= 2 .3 3
3
91 * Wax-1 + 92* ax 4 + g3 * ax_ + 94 * ax 6
_
Wax- 2 = first weighted average value =
¨
E
3 *2.33 1 * 8 1 * 3 + 1 *2
=
6
* Wax-2 + g2 * ax, + q * ax8 + 94 * ax9
ax- 3 = second weighted average value =
LYs
3*3.33+1*1+1*0+1*0
6
[0076]
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.
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[0077]
Thus, with respect to Equation 1, the values ax_Ri*m)+11, ax_Ri*m)+21, and
ax _[(0m)+31 are
used in the calculation of a weighted average value wa,_(i+i). According to
the example of
Fig. 5, "i" can range from 1 to 9, but for purposes of Equation 1, "i" ranges
from 1 to 8.
Accordingly, the 27 acceleration values (i.e., ax j,
= 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,
comprises 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.
[0078]
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-m= maximum acceleration in the first direction =
max(wax- = maximum value of the initial arithmetic and weighted averages (wax-
calculated.
Based on the results from Table 2 of Fig. 6, max(wax- = ax- 8= 3.82.
[0079]
It is noted that ax-wa-max may be selected from any number of initial
arithmetic and
weighted average values (wax_ ) calculated. For example, the average values
(wax_
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_ ) 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_ 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 (wx- 0 were considered. However, less than 9 or greater than
9 values of
initial arithmetic and weighted averages (wax_ ) can be considered when
selecting max(ax-wa-
- 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
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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- i) 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_ i) 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_ i) considered may be averaged to determine the maximum
acceleration
in the first direction ax-wa-max
[0080]
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.
[0081]
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¨(L+1) =
way_i * gi + ay_L(i*rn)+1]* 92 + ay _[(iõ)+2] * 93 + ay_[(i*,,)+3] * 94
gs
way_ (i-E1) = 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;
gs = weighting factor where s = 1... m+1, where m is the number of
members in each subset;
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gi = weighting factor of way- i; in the illustrated embodiment, gi = 3, but
could be any value;
g2, g3, g4 = additional weighting factors = 1, but could be other values;
ay_Ri.m) 2j, ay_[(i.m) 3]; where i = 1 ... (n-1); ay_Rt.m) 1i,
ay_Ri*m)+21, ay_[(i*111)+3] = 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_t, ay_2, and ay_3) make up a first subset as well.
[0082] The first "start" acceleration values in the second
direction could comprise less than
three or more than three values and the number of members in each subset -in"
could likewise
comprise less than three or more than three members.
[0083] 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. 8.
way_ 1 = arithmetic average of the first three "start" acceleration values in
the second
ay + ay_2 + ay 3 0.25 + 0.49 + 0.52
direction = _____________________ ¨ ____________ = 0.42
3
way_i * gi + ay_4 * g2 + ay_s * g3 + ay_6 * 94
Way- 2 = first weighted average value - ______________________________________
3 * 0.42 + 1 * 0.54 + 1 0.75 + 1 * 0.72
_____________________________________ = 0.55
6
[0084] 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.
[0085] In 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_ i) = maximum value of the initial arithmetic and weighted averages
(way- i)
calculated.
Based on the results from Table 4 of Fig. 9, max(way- i) = way-2= 0.55.
[0086] It is noted that ay-wa-max may be selected from the
initial arithmetic average or any
number of weighted averages (way-(i 1)) 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_ ) 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.
[0087]
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-wa-max). 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.
[0088]
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-wa-max 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-wa-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-wa-max) = 0.55. This value falls within the high acceleration range, which
corresponds to a
correction factor of +10%.
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[0091]
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 + corrx + cony)
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 corrx = - 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).
A sample calculation for max.acc based on the sample values discussed above
will now
be provided.
max.acc = max(wax_ i) * (1 + corrx + cony) = 3.82 * (1 -0.05 + 0.1) =
4.01
[0092]
Hence, in this sample, the controller 103 communicates with the traction
motor
controller 106 so as to limit the maximum positive acceleration (speed is
increasing) of the
truck 10 in the first direction during a next semi-automated or remote control
operation to 4.01
m/s2.
[0093]
It is also contemplated that the controller 103 may calculate a first value
indicative
of only 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.
[0094]
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.
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Acceleration may also be derived from the angular position of the travel
switch 54 relative to
a 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.
[0095]
Acceleration in the transverse direction TR or second direction can be
determined
using the following equation: acceleration y = v2/r
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.
[0096]
The table of Fig. 5 represents a monitored drive parameter during a single
manual
operation. However, embodiments also contemplate monitoring and storing drive
parameter
data for more than a single manual operation of the truck 10. For example,
data for one or
more drive parameters can be monitored and stored for any number of the most
recent manual
operations.
[0097]
The controller 103, therefore, can define a beginning and an ending to each
manual
operation so that the data pertaining to each manual operation can remain
segregated from data
pertaining to a different manual operation. A particular manual operation can
be considered to
begin when an operator is on the truck 10, such as indicated by a presence
sensor 58, and moves
the truck 10 with at least a minimum speed. Alternatively, a particular manual
operation can
be considered to begin when a drive signal is generated via the travel switch
54 and not via the
remote control device 70. It is still further contemplated that a particular
manual operation can
be considered to begin when the operator is located outside of the operator's
station 30 and
causes the truck to move via activation of the drive control switch 140
located near the top of
the second end section 14B of the power unit 14 of the truck 10. The
particular manual
operation can be considered to end when the truck 10 remains stationary for at
least a
predetermined time period. Alternatively, the particular manual operation can
be considered
to end when the truck 10 is stopped and the operator exits the truck.
Alternatively, the
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particular manual operation can be considered to end when the operator
initiates a semi-
automated driving operation via the remote control device 70. Also, a manual
operation can be
considered to end when an operator exits the platform of the truck 10 even
when the truck 10
is still moving.
[0098]
As noted above, the monitored and stored data (whether from a single manual
operation or from multiple manual operations) can then be used for controlling
implementation
of a subsequently-occurring semi-automated driving operation of the truck 10.
[0099]
Clearing, or resetting, the stored data collected during one or more recent
manual
operations can be beneficial during or after certain driving operations of the
truck 10. For
example, data for monitored drive parameters collected and stored while a
first pallet and items
carried by or on the first pallet are being transported by the truck 10 may
not be relevant to
implementing semi-automated driving operations of the truck 10 once that first
pallet is off-
loaded from the truck 10 and a new empty pallet is acquired. Thus, when anew
pick operation
is commenced by the operator of the truck 10, the previously monitored and
stored data about
the one or more drive parameters during that current manual operation of the
truck 10 can be
discarded or, reset, so that only new monitored data about the one or more
drive parameters is
used to implement subsequently occurring semi-automated driving operations of
the truck 10.
In one embodiment, only the new monitored data about the one or more drive
parameters
collected during the current manual operation or the manual operation just
before the
subsequently occurring semi-automated driving operation is used to implement
the
subsequently occurring semi-automated driving operation and any data from
prior manual
operations occurring before the current manual operation or the manual
operation just before
the subsequently occurring semi-automated driving operation is ignored.
[00100] A typical stock picking operation involves an operator filling 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 truck 10 between various pick
locations where
item(s) I are to be picked, which are typically loaded on one or more pallets
P provided on the
forks 16 of the load handling assembly 12, see Fig. 13, wherein the pallet P
and the items I
define a load L on or carried by the forks 16. Instead of a pallet, a roll
cage, a freezer box or
other special container could be provided on the forks 16 of the load handling
assembly,
wherein the roll cage, freezer box or other special container and picked items
loaded on the roll
cage, freezer box or other special container define a load on or carried by
the forks 16. The
operator may drive the truck 10 manually by using the steering handle 52 and
the travel switch
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54, as noted above, or operate the truck 10 in the remote control mode using
the remote control
device 70 for semi-automated control of the vehicle.
[00101] Accordingly, the controller 103 can analyze the driving operations of
the truck 10
to automatically determine a sequence of operations, or a pattern, that is
likely indicative of the
start of a new pick operation. Under these circumstances, the controller 103
can then reset, or
discard, the collected data about the monitored one or more drive parameters
that occurred
during the current manual operation. The term "current manual operation- can
refer to a
manual operation that is currently taking place, the term -most recent manual
operation" can
refer to a manual operation occurring immediately prior to the current manual
operation that is
still taking place, the term "previous manual operation" can refer to a manual
operation
occurring prior to the most-recent manual operation, and the term "next manual
operation" can
refer to a manual operation occurring subsequent to the current manual
operation. Once the
"current manual operation- ends it can be considered to be the "most-recent
manual operation.-
[00102] Fig. 12 depicts a flowchart of an example algorithm for resetting
stored data related
to a first monitored vehicle drive parameter based on detecting the start of
the pick operation,
according to embodiments of this disclosure.
[00103] In accordance with the method or process of Fig. 12, step 1201
includes the
controller 103 monitoring the first vehicle drive parameter during a manual
operation of the
truck 10 by an operator, i.e., a current manual operation. As described in
detail above, the
monitored first vehicle drive parameter can be related to acceleration of the
truck 10 in a first
direction.
[00104] Thus, in step 1203, the controller 103 can store data related to the
monitored first
vehicle drive parameter. In the example of Fig. 5, the stored data can be
individual acceleration
values of the truck 10 occurring during a manual operation of the truck 10.
Furthermore, the
stored data can include a calculated value, i.e., maximum acceleration of the
truck 10 in the
first direction, based on the individual acceleration values that is used in a
subsequently
occurring semi-automated operation of the truck 10. Thus, the controller 103
is configured to
use the stored data for implementing a semi-automated driving operation of the
truck 10 that
occurs subsequent to the manual operation of the truck 10 referred to in step
1201.
1001051 However, if the stored data includes data collected during the current
manual
operation occurring before a new pick operation commences, then that stored
data may not be
relevant to a semi-automated operation occurring after that new pick operation
is initiated and
completed. Accordingly, in step 1205, the controller detects operation of the
truck 10
indicative of a start of a pick operation occurring during the current manual
operation of the
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truck 10. Upon detecting the start of the pick operation, the controller 103,
in step 1207, can
then reset the stored data related to the monitored first vehicle drive
parameter. Resetting the
stored data can include clearing, or discarding, the stored data collected
during the current
manual operation of the truck 10 from the start of the current manual
operation until detection
and start of the new or most recent pick operation.
[00106] Once the stored data is reset, then the controller 103 can resume
monitoring of the
first vehicle drive parameter after resetting the stored data. This newly
acquired data related
to monitoring of the first drive parameter can then be used for implementing a
subsequently
occurring semi-automated driving operation of the vehicle.
[00107] In at least one embodiment, the detected operation of the truck 10
indicative of a
start of a pick operation comprises detecting a transition from the truck 10
being manually
driven with a raised load handling assembly 12 to the truck 10 being stopped
with a lowered
load handling assembly 12, see Fig. 13. In other words, the controller 103
detects that the truck
which was moving by manual operation has now stopped and also that the load
handling
assembly 12, which was in a raised position, has been lowered. As noted above,
the controller
103 can determine if the truck 10 is moving or stopped and the distance that
the truck has
travelled via signals from the accelerometer 1103 or motor angular velocity
signals from the
traction controller 106. As also noted above, the controller 103 can determine
the height of the
load handling assembly 12, i.e., whether the load handling assembly is in a
raised position or
in a home or lowermost position, relative to ground from signals generated by
one or more of
height sensors or switches alone or in combination with the load sensor LS.
The raised position
of the load handling assembly 12 would be any position above the lowermost
position. This
sequence of operations is particularly indicative of the start of a new pick
operation when the
raised load handling assembly 12 bears a substantially non-zero load and the
lowered load
handling assembly 12 bears a substantially zero load. As noted above, the
controller 103 can
determine the weight of a load on the forks 16 from signals generated by the
load sensor LS.
In Fig. 13, the forks 16 of the load handling assembly 12 have been lowered so
that the pallet
P is no longer supported by the forks 16 and, instead, is supported by a floor
F or other support
surface defining ground. Hence, such a sequence occurs, for example, when the
truck 10
transitions from moving with a loaded pallet P to stopping and then lowering
its forks 16
completely so that the forks 16 no longer support the loaded pallet P. It is
also contemplated
that this sequence of operations may be indicative of the start of a new pick
operation even
when the raised load handling assembly 12 bears either an unloaded pallet or
no pallet.
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[00108] In a further embodiment, the detected operation of the truck 10
indicative of a start
of a pick operation comprises detecting the transition from the truck 10 being
manually driven
with a raised load handling assembly 12 to the truck 10 being stopped with a
lowered load
handling assembly 12, as illustrated in Fig. 13, and detecting movement of the
truck 10 for a
distance at least equal to a length of a load L on the forks 16 after the
forks 16 are lowered, see
Fig. 14. In the Fig. 14 example, the forks 16 have a length only slightly
greater than the length
of the pallet P. However, it is contemplated that a truck may have forks with
an extended
length such that the forks can carry concurrently more than one conventionally
sized pallet. In
such an embodiment, the forks may carry only one pallet at the end of the
forks or two or more
pallets along the entire length of the forks. For example, a point-laser or an
ultrasonic device
could be provided in the second end section 14B for sensing a distance from
the second end
section 14B to a pallet, such as being positioned at the end of the forks.
Hence, the truck 10
may move a distance equal to length of a load L by moving only the length of a
single pallet
when only a single pallet is provided on the forks or a distance equal to the
length of two or
more pallets when two or more pallets are provided on the forks. Thus, once
the forks 16 are
lowered and they are not bearing any load, movement of the truck 10 (without
any load on the
forks 16) is presumably indicative of the truck 10 off-loading a pallet that
it previously had
been bearing.
[00109] The above sequence of operations is even more indicative of a new pick
operation
when the detected operation of the truck 10 further comprises determining that
the operator
drives the truck 10 with the lowered load handling assembly 12 while it is
bearing a
substantially zero load. Movement of the truck 10 by a distance at least equal
to the length of
a load carried by the forks is relevant (as noted above) but driving the truck
10 for a distance
greater than the length of the forks 16 without a load is even more indicative
of commencement
of a new pick operation.
1001101 In yet a further embodiment, the detected operation of the truck 10
indicative of a
start of a pick operation comprises detecting the transition from the truck 10
being manually
driven with a raised load handling assembly 12 to the truck 10 being stopped
with a lowered
load handling assembly 12, as illustrated in Fig. 13, detecting movement of
the truck 10 for a
distance at least equal to a length of the load L on the forks 16 after the
forks 16 are lowered,
as illustrated in Fig. 14, determining that the operator has driven the truck
10 with the lowered
load handling assembly 12 while it is bearing a substantially zero load, and
detecting a
transition from the truck 10 moving with the lowered load handling assembly 12
to the truck
being stopped with the load handling assembly 12 newly raised. In this
instance, the truck
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has travelled for some distance with essentially an empty and lowered load
handling
assembly 12 and has now stopped wherein, after stopping, the operator
subsequently raises the
load handling assembly 12. Especially when the now-raised load handling
assembly 12 bears
a load less than a predetermined amount but more than a substantially zero
load, e.g., the weight
of an empty pallet, a roll cage, a freezer box or other special container,
this sequence of
operations is indicative of the start of a new pick operation. The
predetermined amount might
comprise the weight of a conventional empty pallet, roll cage, freezer box or
other special
container.
[00111]
In other words, the truck 10 had a substantially non-zero load (i.e., it
was carrying
a pallet P with items I) and the truck 10 then stopped, lowered the pallet P
and the items I on
the pallet P. wherein the pallet P and the items I define the load L on the
forks 16, and proceeded
to move with the lowered load handling assembly 12. In particular, that
lowered load handling
assembly 12 supported essentially no load whatsoever and, therefore, was
bearing a
substantially zero load while the truck 10 was moving. Afterwards, the truck
10 stopped and
raised the load handling assembly 12 such that the now-raised load handling
assembly 12 was
bearing a load but the load was less than the predetermined amount. One such
example would
be when the load handling assembly 12 is bearing merely an empty pallet P such
that an
operator is about to begin a new picking operation. Under these circumstances,
the controller
103 can detect from the load sensor LS that the previously-lowered load
handling assembly 12
was empty and bearing a substantially zero load but is now bearing at least
the weight of a
pallet which is more than the substantially zero load. However, the weight of
the pallet P by
itself is less than the weight of the pallet in addition to one or more items
I on the pallet P; thus
the controller 103 determines from signals generated by the load sensor LS
that the load
handling assembly 12 is bearing a load that is more than the substantially
zero load but is less
than that of a loaded, or semi-loaded, pallet. Accordingly, when detecting
that the now-raised
load handling assembly 12 is bearing a load less than a predetermined amount,
the controller
103 may be detecting that the load bearing assembly 12 is bearing a load equal
to the weight
of a conventional empty pallet.
[00112] As described above, with respect to step 1207, once the controller 103
detects the
start of the pick operation, the controller 103 can then reset the stored data
related to the
monitored first vehicle drive parameter. Additionally, the stored data can
include data related
to a monitored second vehicle drive parameter during the manual operation of
the truck 10 by
the operator, wherein the controller 103 is configured to use the stored data
of the monitored
first and the second vehicle drive parameter for implementing the semi-
automated driving
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operation of the truck 10 subsequent to the manual operation of the truck 10.
Thus, in step
1207, the controller 103 can then reset the stored data related to the
monitored first vehicle
drive parameter and also the monitored second vehicle drive parameter. Hence,
the controller
103 can use Equations 1-5, set out above, and the stored data related to the
monitored first and
second vehicle drive parameters collected since the most recent picking
operation began while
ignoring data collected prior to the most recent picking operation to
calculate a maximum
acceleration in the first direction ax-wa-max and a maximum acceleration in
the second direction
(ay-wa-max) and from those calculations determine a maximum acceleration max.
acc to be used
in the first direction during the next semi-automated driving operation.
[00113]
U. S . Provisional Patent Application No. 62/892,213, entitled "Adaptive
Acceleration for Materials Handling Vehicle," filed on August 27, 2019, is
incorporated by
reference in its entirely herein and U.S. Serial No. 16/943,567 filed on July
30, 2020 is also
incorporated by reference in its entirety.
[00114] Having thus described the present application in detail and by
reference to
embodiments and drawings thereof, it will be apparent that modifications and
variations are
possible without departing from the scope defined in the appended claims.
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