U.S. patent application number 15/585844 was filed with the patent office on 2018-11-08 for pick and put location verification utilizing rf received signal strength.
This patent application is currently assigned to INTERMEC, INC.. The applicant listed for this patent is INTERMEC, INC.. Invention is credited to Mehul PATEL, Erik TODESCHINI.
Application Number | 20180324550 15/585844 |
Document ID | / |
Family ID | 62110932 |
Filed Date | 2018-11-08 |
United States Patent
Application |
20180324550 |
Kind Code |
A1 |
TODESCHINI; Erik ; et
al. |
November 8, 2018 |
PICK AND PUT LOCATION VERIFICATION UTILIZING RF RECEIVED SIGNAL
STRENGTH
Abstract
An inventory tracking system includes a plurality of emitters
that each emit a wireless signal and are placed at known locations
relative to a plurality of storage areas in a warehouse, including
a first storage area for storage of a specified item. The system
further includes a mobile device that travels with a material
handler. The mobile device: receives a first wireless signal from a
first emitter that is one of the plurality of emitters; calculates
a first distance between the material handler and the first emitter
based on the first wireless signal; determines that the material
handler is located at a stocking location for the first storage
area based on the first distance and the known location of the
first emitter; and sends a message indicating that the material
handler is at the stocking location for the first storage area.
Inventors: |
TODESCHINI; Erik;
(Morristown, NJ) ; PATEL; Mehul; (Morristown,
NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTERMEC, INC. |
Lynnwood |
WA |
US |
|
|
Assignee: |
INTERMEC, INC.
Lynnwood
WA
|
Family ID: |
62110932 |
Appl. No.: |
15/585844 |
Filed: |
May 3, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 61/6022 20130101;
H04B 17/318 20150115; H04W 4/025 20130101; G06Q 50/28 20130101;
H04W 48/16 20130101; H04W 4/023 20130101; H04W 4/80 20180201; G01S
5/14 20130101; G06Q 10/087 20130101; G01S 5/0252 20130101 |
International
Class: |
H04W 4/02 20060101
H04W004/02; H04B 17/318 20060101 H04B017/318; H04L 29/12 20060101
H04L029/12; H04W 48/16 20060101 H04W048/16; H04W 4/00 20060101
H04W004/00; G06Q 10/08 20060101 G06Q010/08; G01S 5/02 20060101
G01S005/02; G01S 5/14 20060101 G01S005/14 |
Claims
1. A system, comprising: a plurality of emitters that each emit a
wireless signal and are placed at known locations relative to a
plurality of storage areas where items are stored; a mobile device
comprising an antenna and being configured for: receiving a first
wireless signal from a first emitter of the plurality of emitters;
calculating a first distance between the mobile device and the
first emitter based on the first wireless signal; determining that
the mobile device is located at a stocking location for a first
storage area of the plurality of storage areas based on the first
distance between the mobile device and the first emitter, the known
location of the first emitter and a comparison of the calculated
first distance with a threshold, wherein the threshold is
configurable based on density of bins in the first storage area;
and sending a message indicating that the mobile device is at the
stocking location for the first storage area in response to the
determining that the mobile device is located at the stocking
location.
2. The system of claim 1, wherein the mobile device determines that
a material handler is located at the stocking location for the
first storage area when the first distance is below the threshold,
and determines that the material handler is located at the stocking
location for a predetermined period of time before sending the
message.
3. The system of claim 1, wherein the mobile device calculates the
first distance based on a received strength of the first wireless
signal.
4. The system of claim 3, wherein the mobile device calculates the
first distance based on the following formula (1):
RSSI=-10*n*log(d)+A (1) where: d is the distance, A is a calibrated
transmission power, n is a signal propagation constant, and RSSI is
the received strength of the first wireless signal.
5. The system of claim 1, wherein the mobile device determines an
identity of the first emitter based on the first wireless signal,
and uses the identity to determine the known location of the first
emitter.
6. The system of claim 1, wherein the mobile device instructs a
material handler to go to the stocking location for the first
storage area prior to receiving the first wireless signal.
7. An inventory management system, comprising: a plurality of
emitters that each emit a wireless signal and are placed at known
locations relative to a plurality of storage areas in a warehouse,
including a first storage area for storage of a specified item; a
mobile device that travels with a material handler, the mobile
device: receiving a first wireless signal from a first emitter that
is one of the plurality of emitters; calculating a first distance
between the material handler and the first emitter based on the
first wireless signal; determining that the material handler is
located at a stocking location for the first storage area based on
the first distance, the known location of the first emitter and a
comparison of the calculated first distance with a threshold,
wherein the threshold is configurable based on density of bins in
the first storage area; and sending a message indicating that the
material handler is at the stocking location for the first storage
area.
8. The system of claim 7, wherein the mobile device determines that
the material handler is located at the stocking location for the
first storage area when the first distance is below the threshold,
and determines that the material handler is located at the stocking
location for a predetermined period of time before sending the
message.
9. The system of claim 8, wherein the mobile device receives a
second wireless signal from a second emitter that is one of the
plurality of emitters, calculates a second distance to the second
emitter based on the second wireless signal, and uses the second
distance and the known location of the second emitter to determine
that the material handler is located at the stocking location for
the first storage area.
10. The system of claim 9, wherein the mobile device determines
that the material handler is located at the stocking location for
the first storage area using multilateration.
11. The system of claim 10, wherein the mobile device receives a
third wireless signal from a third emitter that is one of the
plurality of emitters, calculates a third distance to the third
emitter based on the third wireless signal, and uses the third
distance and the known location of the third emitter to determine
that the material handler is located at the stocking location for
the first storage area.
12. The system of claim 9, wherein the mobile device calculates the
first distance based on a received strength of the first wireless
signal.
13. The system of claim 7, wherein the mobile device calculates the
first distance based on the following formula (1):
RSSI=-10*n*log(d)+A (1) where: d is the distance, A is a calibrated
transmission power, n is a signal propagation constant, and RSSI is
the received strength of the first wireless signal.
14. The system of claim 9, wherein the mobile device calculates the
first distance based on a time of flight of the first wireless
signal.
15. The system of claim 7, wherein the mobile device determines an
identity of the first emitter based on the first wireless signal,
and uses the identity to determine the known location of the first
emitter.
16. The system of claim 15, wherein the mobile device determines
the identity based on a MAC (media access control) address of the
first emitter, obtained from the first wireless signal.
17. The system of claim 15, wherein the mobile device determines
the identity based on a beacon ID of the first emitter, obtained
from the first wireless signal.
18. The system of claim 7, wherein the plurality of emitters are
Bluetooth low-energy (BLE) beacons.
19. The system of claim 7, wherein the message includes an
instruction to the material handler to remove a quantity of a
specified item from the first storage area, or add a quantity of
the specified item to the first storage area, the first storage
area being for storage of the specified item.
20. A mobile device: comprising an antenna; and a processor
configured to: receive, from the antenna, a first wireless signal
from a first emitter of a plurality of emitters, each of the
plurality of emitters emit a wireless signal and are placed at
known locations relative to a plurality of storage areas where
items are stored; calculate a first distance between the mobile
device and the first emitter based on the first wireless signal;
determine that the mobile device is located at a stocking location
for a first storage area of the plurality of storage areas based on
the first distance between the mobile device and the first emitter,
the known location of the first emitter and a comparison of the
calculated first distance with a threshold, wherein the threshold
is configurable based on density of bins in the first storage area;
and send a message indicating that the mobile device is at the
stocking location for the first storage area in response to the
determining that the mobile device is located at the stocking
location.
Description
BACKGROUND
[0001] During order fulfillment operations such as stocking and
picking in a storage location such as a warehouse, a common source
of inaccuracy is caused by a stocker or material handler stocking
(or picking) a product at an incorrect location.
[0002] Some systems, such as pick to voice, address this by
requiring the material handler to read a confirmation code that is
printed at each location to verify that they are in fact at the
correct spot, picking or stocking the correct item. This solution
however, is fallible as it is common for the material handlers to
memorize these confirmation codes and speak back the correct code
to the system while picking/placing at an incorrect location.
SUMMARY
[0003] The above problems are solved in several embodiments by a
warehouse including a plurality of storage areas where items are
stored, and a plurality of emitters that each emit a wireless
signal and are placed at known locations relative to the plurality
of storage areas, including a first storage area that is one of the
plurality of storage areas, the first storage area being for
storage of a specified item. The warehouse further includes a
mobile device that travels with a material handler. The mobile
device: receives a first wireless signal from a first emitter that
is one of the plurality of emitters; calculates a first distance
between the material handler and the first emitter based on the
first wireless signal; determines that the material handler is
located at a stocking location for the first storage area based on
the first distance and the known location of the first emitter; and
sends a message indicating that the material handler is at the
stocking location for the first storage area.
[0004] An inventory tracking system includes a plurality of
emitters that each emit a wireless signal and are placed at known
locations relative to a plurality of storage areas in a warehouse,
including a first storage area for storage of a specified item. The
system further includes a mobile device that travels with a
material handler. The mobile device: receives a first wireless
signal from a first emitter that is one of the plurality of
emitters; calculates a first distance between the material handler
and the first emitter based on the first wireless signal;
determines that the material handler is located at a stocking
location for the first storage area based on the first distance and
the known location of the first emitter; and sends a message
indicating that the material handler is at the stocking location
for the first storage area.
[0005] In some embodiments, the mobile device determines that the
material handler is located at the stocking location for the first
storage area when the first distance is below a predetermined
threshold, and determines that the material handler is located at
the stocking location for a predetermined period of time before
sending the message. In some embodiments, the mobile device
receives a second wireless signal from a second emitter that is one
of the plurality of emitters, calculates a second distance to the
second emitter based on the second wireless signal, and uses the
second distance and the known location of the second emitter to
determine that the material handler is located at the stocking
location for the first storage area. In some embodiments, the
mobile device determines the location of the material handler using
multilateration. In some embodiments, the mobile device receives a
third wireless signal from a third emitter that is one of the
plurality of emitters, calculates a third distance to the third
emitter based on the third wireless signal, and uses the third
distance and the known location of the third emitter to determine
that the material handler is located at the stocking location for
the first storage area. In some embodiments, the mobile device
calculates the first distance based on a received strength of the
first wireless signal. In some embodiments, the mobile device
calculates the first distance based on the following formula (1):
(1) RSSI=-10*n*log(d)+A, where: d is the distance, A is a
calibrated transmission power, n is a signal propagation constant,
and RSSI is the received strength of the first wireless signal. In
some embodiments, the mobile device calculates the first distance
based on a time of flight of the first wireless signal. In some
embodiments, the mobile device determines an identity of the first
emitter based on the first wireless signal, and uses the identity
to determine the known location of the first emitter. In some
embodiments, the mobile device determines the identity based on a
MAC (media access control) address of the first emitter, obtained
from the first wireless signal. In some embodiments, the mobile
device determines the identity based on a beacon ID of the first
emitter, obtained from the first wireless signal. In some
embodiments, the plurality of emitters are Bluetooth low-energy
(BLE) beacons. In some embodiments, the message includes an
instruction to the material handler to remove a quantity of the
specified item from the first storage area, or add a quantity of
the specified item to the first storage area. In some embodiments,
the mobile device instructs the material handler to go to the
stocking location for the first storage area prior to receiving the
first wireless signal.
[0006] Embodiments herein provide a solution to the above-described
stocking problems by using received signal strength of wireless
(sometimes radio-frequency) beacons as a confirmation of correct
pick location. Several embodiments utilize small, inexpensive
Bluetooth low-energy (BLE) beacons that can be mounted at each pick
location. These beacons need not be equipped with any other
features other than a simple BLE radio, making them quite
inexpensive and useful in other ways, such as indoor positioning
for other purposes such as tracking and productivity metrics
analysis of material handlers. Some embodiments also use a smart
device that is carried by the material handler or mounted on the
forklift that contains a BLE radio. When a material handler is
directed to their next stocking location (via voice, light or other
mechanism) they navigate their forklift to the stocking location.
Their smart device software is aware of the Bluetooth MAC address
that belongs to the beacon located at the next stocking
location.
[0007] This mapping is done ahead of time when the warehouse is
outfitted with these beacons. The smart device listens to all BLE
devices until it finds the one it is looking for. Once found, it
monitors the received signal strength of the beacon's advertising
packet. This packet contains the transmit power of the beacon,
which along with the received signal strength can be used to
estimate the distance to the beacon, as RF signal strength
decreases in a predictable/measureable way the greater the
separation between the transmitter and the receiver. It is this
property that is the basis of some types of indoor positioning
techniques, such as Multilateration and RF fingerprinting.
[0008] As the material handler approaches the stocking location,
the received signal strength of the beacon increases. The signal
strength and transmit power are used to compute a distance to the
beacon. Once the material handler has sustained a distance to the
beacon below a predetermined threshold (e.g. 1.5 meters) for a
predetermined amount of time (e.g. 5 seconds) the business logic
app (or other software) running on the material handler's smart
phone (or other mobile device) will consider the location to be
verified. Once the location has been confirmed, the material
handler can be told the pick count (via software graphical-user
interface (GUI), verbally, or other means) and can continue their
stocking operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is an isometric drawing of a warehouse according to
one embodiment.
[0010] FIG. 2 is a two-dimensional drawing of a storage area
according to one embodiment.
[0011] FIG. 3 is a flow chart of functions of a mobile device
according to one embodiment.
[0012] FIG. 4 is a diagram of a warehouse according to one
embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS
[0013] FIG. 1 shows a warehouse 100 according to one embodiment,
implementing an embodiment of an inventory management system 160
described herein. Warehouse 100 contains a rack 150 where items,
such as parts or merchandise, are stored. Rack 150 includes a
plurality of storage areas 140, which in some embodiments are
particular locations on a shelf of rack 150. As shown in FIG. 2,
each storage area 140 contains a specified item 200 stored therein.
Warehouse 100 contains several emitters 130, whose locations are
known relative to the storage areas 140. Emitters 130 emit wireless
signals 132. In this embodiment, emitters 130 are mounted on rack
150.
[0014] In some embodiments, emitters 130 are small BLE beacon
devices with power supplies. An off-the-shelf BLE beacon is used in
some embodiments, and almost any type of wireless beacon can be
used. In some embodiments, an emitter 130 is mounted at each
stocking location 160, for each storage area 140, and its BLE MAC
(media access control) address is stored in a database and
associated with that particular stocking location 160. In several
embodiments, even where an emitter 130 is not located at each
stocking location 160, the relative location of emitters 130
relative to stocking locations 160 or storage areas 140 is
known.
[0015] Items 200 are removed from and stocked in storage areas 140
by a material handler 120. In this embodiment, material handler 120
is a forklift operator. However, in other embodiments, material
handler 120 is a worker without a vehicle, a machine, a robot, or a
drone. Material handler 120 can be anything capable of stowing
items 200 in or retrieving items 200 from storage areas 140. In
order to retrieve (pick) or stock an item 200 from a particular
storage area 140, material handler 120 should be located at the
storage location 160 associated with that particular storage area
140. Material handler 120 is equipped with a mobile device 110 that
travels with the material handler 120 and determines the location
of material handler 120 relative to storage areas 140 and storage
locations 160.
[0016] In this embodiment, mobile device 110 has a processor
executing software or instructions on a computer-readable storage
medium. As shown in FIG. 3, when an order is received by mobile
device 110, mobile device 110 instructs material handler 120 to go
to stocking location 160 associated with the storage area 140
containing a specified item 200 that is the subject of the order.
The software instructs mobile device 110 to listen for signals 132
from all emitters 130 using a receiver connected thereto. Material
handler 120 then travels toward the stocking location 160 indicated
by mobile device 110. Meanwhile, mobile device 110 continues to
listen for signals 132 in its vicinity while looking for a
particular Bluetooth MAC address (or other identifying information
obtained from signals 132) corresponding to the intended emitter
130 (which corresponds to the desired stocking location 160,
storage area 140, and item 200). When found, mobile device 110
reads the transmit power contained within the advertisement packet
of emitter 130 and notes the received signal strength of the signal
132 emitted from emitter 130. In some embodiments, mobile device
then calculates the approximate distance to emitter 130 using the
following formula:
RSSI=-10*n*log(d)+A (1)
[0017] where d=distance, A=calibrated tx Power, n=signal
propagation constant and [RSSI]=dBm.
[0018] The signal propagation constant n is approximately 2 in free
space, but n can be adjusted for measurements through walls, as a
wall could reduce the received signal strength by approximately
.about.3 dBm. The calibrated tx (transmission) Power is the
measured signal strength at one meter and is what emitter 130
transmits within its advertisement packet (e.g. signal 132) in
several embodiments.
[0019] In other embodiments, such as those using ultra-wide band
beacons for emitters 130, mobile device 110 calculates the time of
flight of the signal 132 to determine the distance to the emitter
130.
[0020] In some embodiments, the software on mobile device 110
continuously calculates this distance each time it reads an
advertisement packet in a signal 132. Once the calculated distance
is at or below a certain threshold value (e.g. 1.5 meters) for a
certain amount of time (e.g. 5 seconds) the software signals that
the stocking location has been confirmed. The software (in some
embodiments a business logic application) then communicates the
pick or stock quantity to the material handler and the stocking
operation continues. After the quantity is messages to the material
handler, the material handler performs the stocking operation (i.e.
loading the quantity of the specified item 200 into the storage
area 140, or removing the quantity of the specified item 200 from
the storage area 140). The threshold values used for this pick
confirmation are configurable for the specific use case. Storage
areas 140 containing bins that are further apart might allow for a
greater distance from an emitter to confirm that the material
handler 120 is in the desired stocking location 160, where denser
storage areas 140 may require a tighter tolerance. In some
embodiments, this system is used to increase the accuracy of many
different types of picking & stocking systems (pick to voice,
pick to light, etc.).
[0021] In another embodiment, emitters 130 are not placed at every
stocking location 160, but are distributed throughout warehouse 150
at locations relative to stocking locations 160 that are known. In
this embodiment, mobile device 110 uses the calculated distances to
and identities of two or more emitters 130 to determine the
location of material handler 120 within warehouse 100 (and relative
to stocking locations 160). This is achieved by receiving signals
132 from two or more emitters 130 and multilateration. More
accurate location information can be obtained by receiving signals
132 from three or more emitters 130 and multilateration (i.e. using
calculated distances and identities of three or more emitters).
Such an embodiment is shown in FIG. 4, where three emitters 130 are
placed in warehouse 100, and mobile device 110 calculates distances
430 to each of the three emitters. Mobile device 110 then
calculates location of material handler 120 based on known
locations of emitters 130. This determined location is then used to
confirm that material handler 120 is at desired stocking location
160, so that the stocking operation can proceed.
[0022] The warehouse, system, and mobile device functionality
described herein represent a technological improvement to the field
of digital inventory management. As discussed previously, various
computerized solutions have been devised to prevent errors by
material handlers in stocking and retrieving goods in storage.
However, these solutions are easily circumvented. The present
systems solve this problem using a property unique to the field of
wireless communication; namely, that a distance to an emitter can
be determined based on received signal strength. Accordingly, this
is a solution necessarily rooted in technology.
[0023] Although the invention has been described with reference to
embodiments herein, those embodiments do not limit the scope of the
invention. Modifications to those embodiments or different
embodiments may fall within the scope of the invention.
* * * * *