Patent Application
20230141591
The present invention is directed to order-fulfilment and inventory management, and in particular to load unit warehousing operations.
Load units (LUs; e.g. inventory totes, receptacles, shipping cartons, etc.) are commonly tracked within a warehouse or order fulfilment facility by messages sent between a programmable logic controller (PLC) and the warehouse management system (WMS) software. If a mechanical fault or manual intervention moves, dislodges, or removes a load unit from its stored location, the inventory as tracked by the WMS may become inaccurate. Inaccuracies regarding the location of load units within the warehouse may result in machine faults, inaccurate retrieval of load units, and downtime for correction. Because inventory load units are tracked via the PLC and WMS software, any mechanical mishaps within the warehouse may not be recognized and registered with the WMS.
Typically, a load unit is only scanned when it enters a particular function of the warehouse, such as when a load unit enters an automated storage and retrieval system (ASRS), and load handling units (LHUs; e.g. shuttles, autonomous mobile robots (AMRs), conveyors, and the like) then transport the load unit to its assigned location within the ASRS. The load unit is not scanned again or tracked by the PLC or WMS until it leaves the ASRS. Therefore, any malfunctions or miscues that occur while the load unit is within the ASRS may result in faults or mishaps, such as the load unit missing its assigned location. For example, if a load unit is stored at a location other than its assigned location, the WMS may direct a shuttle to the assigned location to retrieve the load unit, but the shuttle may not find the load unit at the assigned location and the shuttle may register an error, move to the next assigned task, or retrieve an incorrect load unit that is nearby where the target load unit should have been. Therefore, the WMS would be unable to locate that load unit unless the ASRS is manually audited. As such, the actual inventory on hand and the positions of particular inventory within the warehouse may be different as compared to the inventory and their positions as stored in the warehouse management system.
Intermittent auditing may be required to attempt to maintain a generally accurate inventory database that accurately matches the physical inventory on-hand and the physical inventory's positions within the warehouse. Auditing may be performed by operators manually entering the ASRS and comparing the physical inventory with what is registered in the warehouse management system. Such auditing processes are labor intensive and result in significant downtime for that portion of the warehouse.
The present invention provides a system and method for automatically auditing the inventory within an automated warehouse, such as an automated storage and retrieval system (ASRS). The system and method utilize radio frequency identification (RFID) technologies, including RFID readers and tags, to enable efficient auditing within the warehouse. The automatic warehouse includes a warehouse management system (WMS) having an inventory database detailing what inventory should be present in the warehouse as well as where particular inventory should be stored in the warehouse. The system and method utilize the RFID components to determine actual, physical locations of load units (e.g. totes, receptacles, cartons, etc.) within the warehouse. The warehouse management system (WMS) then compares the determined actual locations of load units with the expected locations in the inventory database and makes appropriate corrections to the database and/or the load units. The system may reduce or eliminate undesirable downtime that typically may be required to audit the inventory stored within a warehouse.
According to one form of the present invention, a method is provided for auditing the inventory of a warehouse by comparing data stored in a WMS with actual physical locations of load units in the storage system to determine if the WMS requires updates or if load units need repositioned in the storage system. The method includes controlling an automated storage system, such as an ASRS, in which inventory items are stored in a plurality of load units stored at storage locations throughout the storage system. One or more RFID readers within the system attempt to read and recognize RFID tags affixed to some or all of the load units that are present in the storage system. RFID readers may be positioned throughout the storage system to form a network and a blanket of coverage for reading RFID tags in the system. Alternatively, a single RFID reader may be coupled to a load handling unit (LHU; e.g. automated shuttle, autonomous mobile robots, and the like) and operable to traverse the storage system and read RFID tags of the load units within the system. Each RFID reader provided is in communication with the WMS. For every load unit RFID tag that is recognized, the respective RFID reader that read the tag transmits the data or information from the tag to the computer of the WMS. The WMS utilizes the data it receives regarding a particular RFID tag and determines a position of that load unit relative to a reference location within the storage system or warehouse, such as relative to the RFID reader that read the tag, for example. The system may include a warehouse positioning system in communication with the WMS, which also receives information from the RFID reader. The positioning system may facilitate determining the location of a particular RFID tag, of RFID readers within the system, the shuttle of the storage system, or other components of the warehouse, as will be appreciated. The method includes comparing the determined location of each load unit (via its RFID tag) with a database or listing of assigned load unit storage locations determined by and/or stored in the WMS. The location assignment database includes an assigned storage location for at least some of the load units within the storage system. The WMS relies on the location assignment database for directing nearly all of the warehouse operations, including directing shuttles to retrieve a particular load unit when its contents are required for order fulfilment or other downstream processes. The WMS then audits the inventory database and location assignment database by determining whether a particular load unit's determined location matches its assigned storage location. If the determined location of a load unit does not match its assigned storage location, the WMS updates that load unit's assigned storage location in the database to correspond to the load unit's actual determined location.
In one aspect, the storage system includes a storage rack defining at least some of the plurality of storage locations and at least one shuttle operable within an aisle of the storage rack. The RFID reader is disposed on the shuttle such that the RFID reader travels throughout the storage rack along with the shuttle. The method includes controlling the shuttle, with the WMS, to traverse along the aisle and monitoring the location of the shuttle with the warehouse positioning system which is adapted to determine a location of the shuttle relative to the storage rack. As the shuttle traverses the aisle, the RFID reader on the shuttle attempting to read and recognize an RFID tag of each load unit that is stored at a storage location adjacent to the aisle. Determining the position of the respective load unit includes correlating the position of the shuttle with each load unit RFID tag that is recognized to determine a location of each respective load unit relative to the storage rack. The RFID reader may be fixed to a portion of the shuttle (e.g. on the shuttle's chassis), moveably coupled to the shuttle (e.g. on an extendable arm of the shuttle), or selectively supported on the shuttle, such as within a load unit supported on the shuttle. For example, the RFID reader may be positioned within a load unit and the shuttle is operable to retrieve the load unit and RFID reader when required for auditing processes. As such, the RFID reader may be stored apart from the shuttle when auditing processes are not required.
In another aspect, the storage rack includes rows extending perpendicular to the aisle and each row has at least one storage location. The shuttle includes an extendable arm selectively operable to extend into a row to attempt to read an RFID tag of a load unit present in that row. The RFID reader is coupled to the extendable distal end of the extendable arm. The task of attempting to read and recognize an RFID tag of each load unit includes the WMS stopping the shuttle along the aisle adjacent a row and then extending the extendable arm toward that row such that the RFID reader is in close proximity to a load unit at a storage location within that row. The RFID reader attempts to read and recognize the RFID tag on the respective load unit. Each row may include a plurality of storage locations for storing load units and the extendable arm is operable to extend beyond the first load unit in a row (i.e. the load unit closest to the aisle) in order to attempt to read an RFID tag of another load unit at a storage location behind the first load unit.
In still another aspect, the storage system includes a storage rack defining at least some of the storage locations of the system and the storage system includes a plurality of the RFID readers positioned in spaced arrangement throughout the storage rack with each RFID reader having a known reference location relative to the storage rack. Each of the RFID readers is in communication with the WMS and operable to read RFID tags of load units which are stored at storage locations which are within sufficiently close proximity to the respective RFID reader. Determining a position of the respective load unit includes the warehouse positioning system receiving information from one of the plurality of RFID readers that has read and recognized the RFID tag of the respective load unit and calculating the location of the respective load unit relative to the storage rack based on information about that RFID tag and the known reference location of that RFID reader.
In yet another aspect, the storage system includes a storage rack having a plurality of levels each level defining a plurality of storage locations. The system includes a shuttle operable to traverse an aisle of at least one of the levels of the storage rack to store and retrieve load units at the plurality of storage locations adjacent the aisle. And the system includes a lift system operable to transport load units between levels of the storage rack. An RFID reader is positioned proximate the lift system for reading RFID tags of load units transported by the lift.
In another form of the present invention, an RFID enabled material handling system is provided for an automated warehouse that includes a warehouse management system with a computer for controlling the material handling system. The system includes an automated storage and retrieval system (ASRS) having a storage rack with a plurality of rack levels defining storage locations that Radio frequency identification (RFID) readers are positioned proximate various portions of the ASRS and each RFID reader has a known location relative to the ASRS which is stored in a database within the WMS. Each RFID reader is in communication with the computer and is configured to read and recognize an RFID tag coupled to a load unit that is present in the ASRS within sufficient proximity to the respective one of the RFID readers. The required proximity within which an RFID tag must pass relative to the RFID reader may be a function of the type of RFID technology utilized with the system (e.g. ultra-high-frequency (UHF) RFID tags, low-frequency (LF) RFID tags, etc.). Each RFID reader communicates information associated with a recognized RFID tag to the computer. The computer is operable to determine a location of a load unit relative to the ASRS (or another reference location within the warehouse) utilizing information of the load unit's RFID tag as provided by the respective RFID reader along with the known location of the respective RFID reader relative to the ASRS.
In one aspect, the ASRS includes a shuttle operable to traverse an aisle of at least one of the plurality of rack levels of the storage rack. An RFID reader is provided with the shuttle and is operable to read and recognize RFID tags of load units that are stored at storage locations adjacent the aisle and/or supported at the shuttle. The RFID reader at the shuttle communicates information associated with a recognized RFID tag to the computer. The RFID reader may either be fixed to a portion of the shuttle, moveably coupled to the shuttle, or selectively supported on the shuttle. For example, the RFID reader may be contained within a load unit such that the RFID reader is readily retrievable, transportable, and dispensable by the shuttle. For example, the shuttle is operable to dispense the load unit containing the RFID reader at a storage location within the ASRS when the shuttle-transported RFID reader is not required.
In another aspect, the material handling system includes a lift system for transporting load units and/or the shuttle between levels of the storage rack. An RFID reader is positioned proximate the lift system for reading RFID tags of load units transported by the lift. In yet another aspect, the material handling system includes a transportation system configured to transport load units to and from the ASRS, such as to the lift system. The transportation system may include one or more RFID readers which are each in communication with the computer for reading and recognizing an RFID tag of a load unit transported by the transportation system. The computer is operable to determine a location of a load unit relative to the RFID reader of the transportation system or another reference location within the warehouse.
Accordingly, embodiments of the present invention provide for a warehouse facility to maintain up-to-date and accurate inventory information, particularly with regard to the location or relative position of a load unit within the warehouse. A system and a method are provided for creating a database of inventory locations based on actual physical locations of stored inventory within the warehouse as well as auditing inventory databases within the system to accurately define where existing inventory is located in the warehouse. The system utilizes RFID readers positioned throughout the warehouse to read RFID tags on load units that are transported in the system as well as stored in the system. The method rectifies or audits the inventory databases by comparing the actual location of an inventory load unit (as determined with RFID systems) with the assigned or stored location of the load units. The assigned locations represent the location in which the computer of the warehouse management system believes a particular load unit to be stored in the warehouse. Auditing the inventory may be necessary if mechanical, hardware, software, or data faults occur. The use of RFID technology within the storage system of the warehouse also enables automation of the auditing process. For example, an autonomous mobile robot may enter the storage system and correct the positioning of a dislodged load unit, thereby relieving a human operator of the otherwise slow and onerous task.
These and other objects, advantages, purposes and features of this invention will become apparent upon review of the following specification in conjunction with the drawings.
Referring now to the drawings and the illustrative embodiments depicted therein, an RFID enabled, automated material handling system 10 (
RFID tags 22 affixed to each load unit 12 provide for information storage and a short-range transmitter for the load unit, and in this manner, unique RFID identifiers may be assigned to each load unit 12 within the system 10. The RFID tag 22 enables an RFID reader 24 and the WMS 16 to match information from the RFID tag 22 of the load unit 12 against the inventory database 20 and/or location assignment database 34 to determine the inventory stored in a particular load unit 12 and that load unit's location within the system 10. The system 10 and method 100 may reduce or eliminate undesirable downtime that is commonly required to audit the inventory within an ASRS. For example, if a load unit is misplaced at an improper storage location (e.g. dropped by an automated shuttle), an operator may be required to physically enter the ASRS to identify the load unit and either reposition in the proper location or update the WMS with the actual location information. Other examples of undesired downtime include mechanical faults and vibrations which may result in load units being out of position as compared to the location that is assigned by the computer and software (e.g. where the computer expects the load unit to be), personnel/operators in the rack mistakenly moving a load unit to a position that is different than determined/assigned by the computer and software, or data of stored inventory within the computer may be lost or corrupted, etc. The system utilizing RFID readers and RFID tags may reduce or eliminate the need for a human operator to enter the storage rack to identify a tote or other load unit that is out of position, which, if required, typically causes a significant amount of downtime. The RFID enabled system and methods may minimize or eliminate the need for barcode scanners throughout the system, which are typically only positioned at entry and exit points of the ASRS to determine when a load unit has entered or exited the ASRS. While it is preferable that all load units include an RFID tag, it will be appreciated that the system and methods remain advantageous in instances where only some of the load units in a warehouse have RFID tags.
Referring now to the illustrative embodiments of
The method 100 includes attempting 104 to read and recognize an RFID tag 22 of each load unit 12 that is present in the ASRS 14 with one or more of the RFID readers 24 positioned within the ASRS. The RFID reader 24 is in communication with the WMS 16 and transmits any information gathered from an RFID tag to the WMS 16. For every load unit RFID tag that is recognized, the computer 18, in coordination with a warehouse positioning system, utilizes information from the RFID reader 24 to determine 106 a global location or position of the respective load unit 12 relative to a reference location within the ASRS 14 or some other global reference point within the warehouse. The computer 18 compares 108 the actual location of the load unit 12 determined at 106 with an assignment database 34 of assigned load unit storage locations which define the assigned, desired, or otherwise predetermined storage locations for at least some of the plurality of load units 12 within the ASRS 14. It is then determined 110, based on the comparison 108 of actual location vs. assigned location, whether a particular load unit's actual, determined location matches its assigned storage location. If the determined location of a load unit 12 does not match its assigned storage location, the computer 18 updates 112 that load unit's assigned storage location in the assignment database 34 to correspond with the load unit's actual, determined location.
As mentioned briefly above, embodiments are contemplated in which a single RFID reader 24 may be adequate to meet the auditing processes requirements of a warehouse. The following describes such an example in which an RFID reader 24a, 24b, 24c, or 24d is transported on the shuttle 26 and may be sufficient without the need for any additional RFID readers (
By providing the RFID reader 24a, 24b, 24c or 24d on the shuttle 26, the system 10 and method 100 may reduce complexity of the WMS 16 and associated programmable logic controllers (PLCs), reduce infrastructure requirements and costs, and optionally enable the shuttle 26 to selectively perform auditing functions when required and/or perform normal shuttle operations (i.e. transporting load units). The method 100 may further include controlling 114 the shuttle 26, with the WMS 16, to traverse along the aisle 32 while monitoring the location of the shuttle 26 with the warehouse positioning system which is adapted to determine a global location of the shuttle 26 (e.g. instantaneous location), and the RFID reader 24a, 24b, 24c or 24d in particular, relative to the ASRS 14 or some other global reference point within the warehouse (
As mentioned above, the RFID reader 24b or 24c may be selectively supported on and transportable on the shuttle 26 (
The system 10 may utilize commonly known and readily available RFID tag and reader technology, in which an optional embodiment is described below. However, in a preferred embodiment, the system 10 utilizes advanced RFID tag and reader technology in which the location of an RFID tag may be accurately determined within a three-dimensional (3D) space (i.e. spatial coordinate system). The advanced RFID reader may also be capable of determining orientation information of a particular RFID tag. The advanced RFID reader and tag technology may be capable of reading RFID tags in many different directions as well as RFID tags that are obscured by other materials, such as tags obscured by other load units. For example, an ASRS may include load units stored two or three units deep in rows and the advanced RFID reader may be capable of reading and determining the location and/or orientation of an RFID tag on any of the load units within a row. As such, the advanced RFID reader is capable of reading the RFID tag 22 of the furthest load unit 12 even though the furthest load unit 12 is positioned at the back of the row, potentially behind two or more intermediate load units that are closer to the main aisle 32.
As briefly mentioned above, the system 10 and method 100 may also utilize commonly known and readily available RFID readers and tags. It will be appreciated that one or more of various types and forms of RFID tags may be utilized with the system and method. Some examples of RFID tag types include ultra-high-frequency (UHF) RFID tags, high-frequency (HF) RFID tags, near field communication (NFC) RFID tags, and low-frequency (LF) RFID tags. In order to utilize such readily available RFID technology, it may be necessary that the system include optional features to enable adequate coverage based on the signal range capabilities of readily available RFID readers. Because readily available RFID readers and tags may have a limited operating or signal range in which a reader can accurately and effectively read an RFID tag, it may be necessary that RFID tags on load units be able to pass within a close proximity to an RFID reader. Accordingly, the system 10 may include a multitude of readily available RFID readers throughout the facility to provide a blanket of RFID reader coverage, for example. As such, in most instances, load units 12 stored at storage locations are within sufficient range of an RFID reader and/or as a load unit passes through the system 10, the RFID tag of the load unit will pass within sufficient range of an RFID reader 24 (
In the preferred embodiment, the contemplated improved or advanced RFID readers and tags require a proximity of a tag relative to the reader that is significantly reduced as compared to previously known or available RFID technology. Additionally, the improved RFID reader is contemplated to be capable of reading or sensing RFID tags through materials that block or impede a line of sight between the reader and the tag. For example, the RFID reader may sense an RFID tag on a subject load unit situated on a storage rack behind two additional load units that are positioned between the subject load unit and the RFID reader. Further, the improved RFID reader is contemplated to be capable of interpreting or determining spatial coordinates of an RFID tag relative to the RFID reader. The reader may also be capable of identifying a relative orientation of the RFID tag relative to the reader. For example, the reader may determine that a particular RFID tag is 0.75 meters away from the reader in the x-coordinate, 1.2 meters from the reader in the y-coordinate, and 0.6 meters from the reader in the z-coordinate. This relative spatial coordinate information is transmitted to the WMS 16 which utilizes the spatial coordinate information to determine, calculate, or otherwise correlate with other known location information, what the global location of a load unit 12. The WMS 16 then compares the global location of the load unit 12 with the inventory database 20 and/or location assignment database 34 to verify, validate, and ultimately audit the inventory information within the WMS 16.
While RFID tags and readers are a preferred information storage unit and identifier for the system 10 and method 100 due to their inherent portability and inconspicuousness, it will be appreciated that other acceptable information storage units and identifiers may be utilized for the system and method within the facility, such as real-time location systems (RTLS) (e.g. ultra-wide band RTLS, Wi-Fi RTLS, or infrared RTLS), for example.
Inventory auditing processes (e.g. validation) may be performed routinely or on demand. Auditing processes may be automatically requested following a machine fault (computer hardware or software malfunction, mechanical failure, etc.), such as to quickly and efficiently correct any errors in the system 10 or to ensure that no critical data loss occurs as a result of the machine fault, for example. Alternatively, a human operator or maintenance technician may manually request an audit or auditing process if they recognize an error or malfunction, or if they believe that there may be an error or malfunction in the system 10. Further, the system 10 and method 100 may be adapted for populating an initial inventory database 20 and/or location assignment database 34. For example, a shuttle 26 may start at the end of one aisle 32 and populate an inventory database 20 as it moves down the aisle 32, attempting 104 to read and recognize the RFID tag 22 of each load unit 12 stored adjacent to that aisle 32. Performing inventory auditing processes routinely may ensure a high degree of accuracy within the system 10, both in terms of real-time inventory management and load handling unit control.
Referring to the illustrative embodiment of
The material handling system 200 includes a transportation system 202 configured to transport load units 12 to and from the ASRS 14 as well as transporting load units 12 and/or individual inventory items to various components or functions of the warehouse (
Thus, the embodiments of the system and method of the present invention provide for auditing the inventory within an automated warehouse utilizing RFID technology. The system and method are also capable of real-time tracking and monitoring of inventory and load units as they travel through and are stored in the warehouse. The system may utilize multiple RFID readers positioned throughout the warehouse to enable adequate RFID signal coverage for real-time, whole warehouse inventory tracking. Alternatively, or in addition to, the system may only require a single RFID reader coupled with an automated shuttle that is capable of traversing a majority of the warehouse storage system to audit the inventory stored in load units throughout the storage system. The system and method are operable when utilizing readily available RFID technologies. Additionally, the system and method of the present invention contemplate advanced or improved RFID technologies with greater detection range, larger information storage capabilities, and the ability to determine a precise spatial location of an RFID tag relative to an RFID reader.
Changes and modifications in the specifically described embodiments can be carried out without departing from the principles of the present invention which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents.
The present application claims priority of U.S. provisional application Ser. No. 63/276,896 filed Nov. 08, 2021, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63276896 | Nov 2021 | US |
