Systems and methods for creating safety zones using mobile robots

Abstract

There are provided systems and methods for creating safety zones at facilities using mobile robots. In one form, the system may include a facility with pathways and with a guide system for facilitating movement along the pathways and mobile robots configured to move along the pathways. Each mobile robot may include a locomotion system for movement of each mobile robot along the pathways and an extendable and retractable member for engaging a support adjacent to a pathway. The system may further include supports with receiving portions that receive the extendable and retractable members of the mobile robots. In the system, a blocking position may be defined where a receiving portion has received an extendable and retractable member of a mobile robot, thereby limiting movement of the mobile robot and blocking other mobile robots from passing along a pathway occupied by the mobile robot at the blocking position.

Description

SYSTEMS AND METHODS FOR CREATING SAFETY ZONES USING MOBILEROBOTSCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of and priority to U.S. Provisional Application Number 63 / 536,880, filed September 6, 2023, which is incorporated by reference herein in its entirety.TECHN ICAL FI ELD

[0002] This invention relates generally to a safety zone at a facility, and more particularly, to a safety zone at a facility created by mobile robots.BACKGROU N D

[0003] Automated storage and retrieval systems (ASRS) are being used increasingly in the context of fulfilling merchandise orders. In some forms, these systems may include mobile robots that move about a storage structure at an order fulfillment facility to pick and transfer containers and items. Sometimes, a mobile robot may become damaged or incapacitated. When a mobile robot becomes damaged or incapacitated, it may become necessary to shut down part or all of the facility to allow handling of the mobile robot.

[0004] There is a need to reduce the number of partial or complete shutdowns that are required to allow handling of a damaged or incapacitated mobile robot. This handling may require a human technician to approach the mobile robot, which may be in an area where other mobile robots are traveling. In this circumstance, the facility ordinarily may need to be partially or completely shut down to ensure the safety of the individual. It would be desirable to create a safety zone about the damaged or incapacitated mobile robot to allow an individual to safely approach it.BRI EF DESCRI PTION OF DRAWI NGS

[0005] Disclosed herein are embodiments of systems, apparatuses and methods for creating safety zones at facilities using mobile robots. This description includes drawings, wherein:

[0006] FIG. 1A is a partial perspective view of an order fulfillment facility in accordance with some embodiments;

[0007] FIG. IB is a partial perspective view of the order fulfillment facility of FIG. lA in accordance with some embodiments;

[0008] FIG. 2A is a schematic view of a safety zone in accordance with some embodiments;

[0009] FIG. 2B is a schematic view of the safety zone of FIG. 2A in accordance with some embodiments;

[0010] FIG. 3 is a schematic view of a safety zone in accordance with some embodiments;

[0011] FIG. 4 is a schematic view of a safety zone in accordance with some embodiments;

[0012] FIG. 5 is a schematic view of a safety zone in accordance with some embodiments;

[0013] FIG. 6 is a schematic representation of a mobile robot blocking system in accordance with some embodiments;

[0014] FIG. 7 is a side view of a mobile robot in accordance with some embodiments;

[0015] FIG. 8 is a perspective view of a pinion of the mobile robot of FIG. 7 in accordance with some embodiments;

[0016] FIG. 9 is a partial cross-sectional view of the mobile robot of FIG. 7 in accordance with some embodiments;

[0017] FIG. 10 is a partial cross-sectional view of the mobile robot of FIG. 7 in accordance with some embodiments;

[0018] FIG. 11 is a partial perspective view of the mobile robot of FIG. 7 in accordance with some embodiments;

[0019] FIG. 12 is a perspective view of a section of a track system in accordance with some embodiments;

[0020] FIG. 13 is a flow diagram in accordance with some embodiments; and

[0021] FIG. 14 is a flow diagram in accordance with some embodiments.

[0022] Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and / or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well- understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and / or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.DETAI LED DESCRIPTION

[0023] The following description is not to be taken in a limiting sense but is made merely for the purpose of describing the general principles of exemplary embodiments. Reference throughout this specification to "one form / ' "one embodiment / ' "an embodiment / ' "some embodiments", "an implementation", "some implementations", "some applications", or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases "in one embodiment," "in an embodiment," "in some embodiments", "in some implementations", and similar language throughout this specification do not all refer to the same embodiment.

[0024] The terms "top" and "bottom," "upper" and "lower" and "vertical" and "horizontal as may be used herein are by way of example and illustrative purposes only and are not meant to limit the description of the embodiments inasmuch as the referenced item can be exchanged in position and orientation. Also, as used herein, the terms "substantially" and / or "about" mean that the specified dimension or parameter may be varied within an acceptable manufacturing tolerance for a given application.

[0025] Generally speaking, pursuant to various embodiments, systems, apparatuses and methods are provided herein for creating safety zones at facilities using mobile robots. In one form, the system includes: a facility with a plurality of pathways and with a guide system for facilitating movement along the plurality of pathways; a plurality of mobile robots configured to move along the plurality of pathways at the facility, each mobile robot including: a locomotion system configured to cooperate with the guide system to facilitate movement of each mobile robot along the plurality of pathways; and an extendable and retractable member configured to engage a support adjacent to a pathway. The system further includes: a plurality of supports with receiving portions, the receiving portions configured to receive the extendable and retractable members of the mobile robots; and a blocking position where a receiving portion has received an extendable and retractable member of a mobile robot, thereby limiting movement of the mobile robot and blocking other mobile robots from passing along a pathway occupied by the mobile robot at the blocking position.

[0026] In some implementations, in the system, the facility includes an order fulfillment facility including a plurality of storage locations configured to store containers containing goods, each storage location being accessible by a pathway; and the plurality of mobile robots are configuredto access the plurality of storage locations to deposit or retrieve containers at the plurality of storage locations. In some implementations, each mobile robot has a sensor configured to detect that the extendable and retractable member engages the receiving portion, when the extendable and retractable member has been extended from the mobile robot when the mobile robot is located at the blocking position. In some implementations, the guide system includes: a track with at least one rail for engagement by the locomotion system of each mobile robot; and / or guidelines disposed in the pathways to facilitate navigation by each mobile robot. In some implementations, the extendable and retractable member includes a shaft and the receiving portion includes a channel, the channel configured to receive the shaft therein. In some implementations, the mobile robot includes a second extendable and retractable member; and in the blocking position, a second receiving portion has received the second extendable and retractable member of the mobile robot. In some implementations, the mobile robot is configured to be electrically charged when in the blocking position by engagement of a charge assembly of the mobile robot with a charging portion coupled to a support. In some implementations, the mobile robot further includes a motor, and the mobile robot deactivates the motor after it is in the blocking position. In some implementations, the system further includes a control circuit configured to: identify a location of a safety zone; instruct mobile robots in the safety zone to leave the safety zone; instruct at least one mobile robot to block at least one access point to the safety zone; and confirm positions of the at least one robot at the at least one access point. In some implementations, the control circuit is further configured to: determine locations of a plurality of access points to the safety zone, in accordance with a blocking plan; and instruct a plurality of mobile robots to move to the locations of the plurality of access points to enter blocking positions at those locations.

[0027] In another form, there is provided a method using mobile robots to create safety zones at facilities. The method includes: providing a plurality of mobile robots configured to move along a plurality of pathways at a facility and with a guide system for facilitating movement along the plurality of pathways, and each mobile robot including: a locomotion system configured to cooperate with the guide system to facilitate movement of each mobile robot along the plurality of pathways; and an extendable and retractable member configured to engage a support adjacent to a pathway. The method further includes: providing a plurality of supports with receiving portions, the receiving portions configured to receive the extendable and retractable members of the mobile robots; at a blocking position, receiving, in a receiving portion, an extendable andretractable member of a mobile robot; and at the blocking position, limiting movement of the mobile robot and blocking other mobile robots from passing along a pathway occupied by the mobile robot at the blocking position.

[0028] In some implementations, with respect to the method, the facility includes an order fulfillment facility including a plurality of storage locations configured to store containers containing goods, each storage location being accessible by a pathway; and the plurality of mobile robots are configured to access the plurality of storage locations to deposit or retrieve containers at the plurality of storage locations. In some implementations, the method further includes: by a sensor of the mobile robot, detecting that the extendable and retractable member engaged the receiving portion, when the extendable and retractable member has been extended from the mobile robot and when the mobile robot is located at the blocking position. In some implementations, the guide system includes: a track with at least one rail for engagement by the locomotion system of each mobile robot; and / or guidelines disposed in the pathways to facilitate navigation by each mobile robot. In some implementations, the extendable and retractable member includes a shaft and the receiving portion includes a channel, the channel configured to receive the shaft therein. In some implementations, the mobile robot includes a second extendable and retractable member, and the method further includes: in the blocking position, receiving, by a second receiving portion, the second extendable and retractable member of the mobile robot. In some implementations, the method further includes: electrically charging the mobile robot when in the blocking position by engagement of a charge assembly of the mobile robot with a charging portion coupled to a support. In some implementations, the mobile robot further includes a motor, and the method further includes: deactivating the motor after the mobile robot is in the blocking position. In some implementations, the method further includes, by a control circuit: identifying a location of a safety zone; instructing mobile robots in the safety zone to leave the safety zone; instructing at least one mobile robot to block at least one access point to the safety zone; and confirming positions of the at least one robot at the at least one access point. In some implementations, the method further includes, by the control circuit: determining locations of a plurality of access points to the safety zone, in accordance with a blocking plan; and instructing a plurality of mobile robots to move to the locations of the plurality of access points to enter blocking positions at those locations.

[0029] In one aspect, and without limitation, this disclosure is directed generally to a facility, such as an order fulfillment facility, that includes multiple mobile robots that operate to pick andtransfer containers in the context of an automated storage and retrieval system. In one form, mobile robots move about the facility and retrieve containers, or totes, of goods that are stored in specific storage locations in the facility, as part of the automated storage and retrieval system. Occasionally, a mobile robot may become damaged, incapacitated, or otherwise cease to function in some intended manner. When this situation occurs, it may require some or all of the facility to shut down while the mobile robot is removed, repaired, or otherwise handled.

[0030] In one aspect, and without limitation, it may be desirable to minimize the number of partial or complete system stops that are required in case of an anomaly involving a mobile robot. Some scenarios of mishaps may require an individual, such as a technician, to physically enter a portion of the system to address the mobile robot. In this instance, the system and / or facility may be shut down partially or completely to ensure the safety of the individual.

[0031] In one aspect, and without limitation, this disclosure provides for defining a safety zone around an area that requires intervention by an individual by utilizing mobile robots present in or near the area as barriers for the safety zone. Generally, the mobile robots may position themselves to block different points of access to the mishap area, thus creating the safety zone. Once a mobile robot is positioned, it may establish a barrier mode and blocking position in which its motor(s) may be deactivated and in which its pinions may be extended to engage an adjoining structure on each side to lock itself in position. One or more sensors (such as safety rated sensors) on the mobile robot may confirm that its pinions are engaged and locked and that it is properly in the blocking position. If the sensor(s) detect that the pinions have become disengaged, a control circuit at the mobile robot in communication with the sensor(s) can initiate an emergency stop (e-stop) of the system, i.e., cause complete stoppage of the system.

[0032] In one aspect, and without limitation, a safety controller (referred to as a safety programmable logic controller (PLC)) on each mobile robot may place the robot in its "safe state" (with pinions extended and motors deactivated) and may monitor the bot in this "safe state." One or more safety rated sensors on the mobile robot may allow the safety PLC to know the positions of the pinions, and in case the pinions are not properly positioned (i.e., not in the "safe state"), the system can be e-stopped. A main safety controller (referred to as a main safety PLC (MSPLC)) may generally control the overall operation: confirming that barrier robots are in position before the technician enters the area and then instructing them to leave after the associate has finished addressing the issue (such as by repairing or removing the downed mobile robot).

[0033] FIG. 1A shows a partial view of an embodiment of an order fulfillment facility 100 showing a storage structure 102, including a number of bays 104 of storage locations 106. In particular, each bay 104 includes a y-z array of storage locations 106 in horizontal rows and level changing towers, or vertical towers, along the rows. As explained below, mobile robots 150 may travel between storage levels in the z-direction within the level changing towers. Pairs of bays 104 may be arranged to face each other, separated by pathways 108. In one form, it is contemplated that the pathways may be aisles 108. An aisle 108 may have a width such that a mobile robot 150 traveling within an aisle 108 may transfer totes to the bays 104 on either side of the aisle 108. As explained hereinafter, the aisles 108 may be wide enough for a human to enter into an aisle 108 between bays 104 to make repairs or otherwise service components within an aisle 108.

[0034] The order fulfillment facility 100 may further include decks 112 (or transit planes or areas) spaced apart at different horizontal levels of the storage structure 102. The decks 112 may extend between the aisles 108 so that robots 150 can maneuver in the x-y plane of each deck 112 to travel between different aisles 108. In some embodiments, the decks 112 may be vertically spaced apart from each other, so that a technician can reach all areas within an aisle 108 serviced by a particular deck 112. The spacing between decks 112 may be different in various embodiments. In addition to providing access to the aisles 108, each pair of decks 112 allows transfers by mobile robots 150 to / from a workstation 110. In some forms, mobile robots 150 may come to a workstation 110 from a first deck 112-1, and mobile robots 150 may exit a workstation 110 from a second deck 112-2. Alternatively, in some forms, mobile robots 150 may come to a workstation 110 from deck 112-2 and exit from first deck 112-1.

[0035] FIG. IB shows examples of workstations 110. In some embodiments, each workstation 110 is equipped to receive a pair of mobile robots 150. A first mobile robot 150 at a workstation 110 may carry product containers (or totes) with items for fulfilling product requests. A second mobile robot 150 at the workstation 110 may carry order containers (or totes) within which items from the product totes are placed to fulfill product requests. Workers at a workstation 110 manually transfer items from a product tote to an order tote under guidance of an inventory control system at the workstation 110.

[0036] The mobile robots 150 for both the product and order totes arrive from one of the decks, for example deck 112-1. Once items are transferred from the product totes to the order totes, the mobile robots 150 may depart the workstation 110, for example via deck 112-2. Mobile robots 150 carrying product and order totes continuously cycle through the workstations 110. In FIG. 1A,each workstation 110 is serviced by a single deck 112, which serves as the entry to, and exit from, the workstation 110. Further details relating to the structure and operation of embodiments of the workstations are disclosed in U.S. Patent No. 10,040,632, issued August 7, 2018, entitled "Automated System for Transporting Payloads", and U.S. Patent No. 11,142,398, issued October 12, 2021, entitled "Order Fulfillment System", which patents are incorporated by reference herein in their entirety. For the purposes of the present technology, it is conceivable that some malfunction may occur at or around an aisle 108, a deck 112, or a workstation 110, which would require service as explained below.

[0037] As noted above, the order fulfillment facility 100 may further include a number of mobile robots 150 for transferring totes or other product containers to and from workstations 110 and storage locations 106 in the bays 104. In certain embodiments, mobile robots 150 may be self- guided so as to move horizontally within aisles 108 to transfer totes or other product containers between the mobile robots 150 and storage locations 106. For example, a track system including horizontal rails may be affixed to bays 104 within an aisle 108 at different vertical levels. The horizontal rails provide access to storage shelves on either side of an aisle 108 in the x-direction on a given level. As noted above, the bays 104 may include level changing towers within which the mobile robots 150 may travel vertically in the z-direction between levels of storage locations 106.

[0038] In another form, the track system may be in the form of guidelines, such as magnetic guidelines, which may include navigational aids, such as RFID tags. The track system may therefore include horizontal rails, guidelines, and / or some combination thereof. In one example, horizontal rails may be used in the aisles 108, while guidelines may be embedded in panels forming at least some of the decks 112. Further details of guidelines and panels that may be used to facilitate navigation by mobile robots 150 are described, for example, in U.S. Application No. 63 / 472,885, filed June 14, 2023, which is incorporated herein by reference in its entirety.

[0039] The decks 112 allow inter-aisle travel of mobile robots 150 at different levels of the storage structure 102. Further details of storage structures, track systems, and mobile robots 150 that may be used in conjunction with the present technology are described for example in the following U.S. patents: U.S. Patent No. 9,139,363, issued September 22, 2015, entitled "Automated System for Transporting Payloads"; U.S. Patent No. 10,435,241, issued October 8, 2019, entitled "Storage and Retrieval System"; and previously mentioned U.S. Patent No.11,142,398, issued October 12, 2021, entitled "Order Fulfillment System"; which patents are each incorporated by reference herein in their entirety.

[0040] Accordingly, in some forms, there is disclosed a facility 100 with pathways 108 and with a guide system for facilitating movement along the pathways 108. The guide system may include a track with at least one rail for engagement by a locomotion system of each mobile robot; and / or guidelines disposed in the pathways 108 to facilitate navigation by each mobile robot. The facility 100 may be in the form of an order fulfillment facility that includes storage locations 106 for storing containers containing goods, with each storage location 106 being accessible by a pathway 108. Further, mobile robots 150 are configured to access the storage locations 106 to deposit or retrieve containers at the storage locations 106.

[0041] The order fulfilment facility 100 described above is one example of a facility 100 where mobile robots 150 move about the facility 100 engaged in certain tasks. During the course of this movement, mobile robots 150 may encounter circumstances that cause them to break down, become incapacitated, or otherwise require repair. These circumstances may be internal (such as an internal component failure) or external (such as running into an obstacle). In these instances, it is desirable to localize the problem by creating a local safety zone so that the entire facility (or a large part of it) does not have to be shut down. Approaches involving the use of safety doors have been proposed, such as described in U.S. Patent No. 11,623,342, issued April 11, 2023, entitled "Configurable Service Isolation Zones for Service of Equipment Employing Moile Robots", which is incorporated by reference herein in its entirety. Approaches described in this disclosure generally involve the use of mobile robots 150 in the facility 100 to create a safety zone about a damaged, incapacitated, dysfunctional, or non-functional mobile robot 150 until it can be repaired or removed to a secure area.

[0042] FIGS. 2-5 show schematic examples of safety zones created by mobile robots in different areas of a facility. FIGS. 2A and 2B show a safety zone 200 shown by the dashed lines where a damaged mobile robot 204 is located in an aisle 202. FIG. 2A shows a top view of four aisles 202 (including one aisle 202 with the damaged mobile robot 204), and FIG. 2B shows a side view of the aisle 202 with the damaged mobile robot 204. In this example, it is contemplated that there is an outer boundary 206 that the mobile robots cannot move through but that technicians may pass through or over in some manner. Further, in this example, there are decks 208 adjacent to the ends of the aisles 202 and level changing towers 210 (with charging rails) at the ends of the aisles 202. In this example, in FIG. 2A, there may be three undamaged mobile robots 212 that arein blocking positions at the righthand end of the aisles 202. The lefthand end of the aisle 202 where the damaged mobile robot 204 is located may be left open to allow a path for removal or recovery of the robot 204. Alternatively, although not shown, there may be an undamaged mobile robot 212 positioned at the lefthand end of the aisle 202 where the damaged mobile robot 204 is located.

[0043] Further, as shown in FIG. 2B, two mobile robots 212 may be in blocking positions to limit vertical movement through a level changing tower 210 from above or below to the aisle 202 with the damaged mobile robot 204. Alternatively, in another form, the mobile robots 212 may not be used to block level changing towers 210, and instead, the level changing towers 210 may include catwalks that may be closed to prevent vertical movement into the safety zone 200. In some forms, it is contemplated that catwalks may intersect and cross level changing towers 210 and may also be used in the facility 100 to get to different levels. These catwalks generally may include access devices (such as a door, gate, or other mechanical barrier) that may be closed to block vertical movement through a level changing tower 210. In some forms, it is desirable to generally block the various points of access to the damaged mobile robot 204 (not shown in FIG. 2B) using catwalks and / or mobile robots 212 in various blocking positions such that only a technician can approach the damaged mobile robot 204. In this manner, mobile robot movement and activity can continue throughout the rest of the facility 100.

[0044] FIG. 3 shows a safety zone 300 defined generally by the deck 308 (or transit plane) where a damaged mobile robot 304 is located on the deck 308. In this example, it is contemplated that there is one side of the deck 308 that the mobile robots cannot move through butthat technicians may pass through or over in some manner (or that there is some form of worker entrance 309 on one side of the deck 308). Further, in this example, the decks 308 are adjacent to the ends of the aisles 302. In this example, as can be seen, there may be ten undamaged mobile robots 312 that are in blocking positions at the ends of the aisles 302. In this example, it is contemplated that the technician may remove the damaged mobile robot 304 through the one remaining open aisle 302 and along a path for recovery of the damaged mobile robot 304. Alternatively, although not shown, an undamaged mobile robot 312 might block this one remaining open aisle 302 if repair is to be performed on the deck 308.

[0045] FIG. 4 shows a safety zone 400 where a damaged mobile robot 404 is located in a lane 403 for a workstation 405. In one form, the workstation 405 may be a static, or stationary, workstation that is one of several workstations in that area. The lanes at or near theseworkstations 405 may be main input and output lanes, and it is desirable to prevent blocking of such high priority lanes. A mobile robot 404 that is incapacitated in the area may greatly decrease workflow through every workstation 405 in that lane 403 and may, in fact, stop all work through those workstations 405. In this example, it is contemplated that a technician may enter the lane 403 at the righthand side of the lane 403. Further, in this example, catwalks 407 are closed to block vertical access to the lane 403. Alternatively, in other forms, undamaged mobile robots may be positioned in blocking positions to limit access to the area through the level changing towers 410. In this example, it is contemplated that the technician may remove the damaged mobile robot 404 along a path of recovery heading back to the right on the lane 403 to the worker entrance point 409.

[0046] FIG. 5 shows a safety zone 500 where a damaged mobile robot 504 is located in a lane503 for a workstation 505. In one form, the workstation 505 may be a dynamic workstation where orders are fulfilled. In this example, it is contemplated that a technician may enter the lane 503 at the lefthand side of the figure. In one form, it is contemplated that the technician may access the lane 503 via a deck 508. In addition, in this example, catwalks 507 are closed to block vertical access to the lane 503. Alternatively, in other forms, undamaged mobile robots may be positioned in blocking positions to limit access to the area through the level changing towers 510. In this example, it is contemplated that the technician may remove the damaged mobile robot504 along a path of recovery heading back to the left on the lane 503 to the worker entrance point.

[0047] FIG. 6 shows a schematic representation of a mobile robot blocking system 600 with a mobile robot 602 in a blocking position. It is generally contemplated that the mobile robot 602 may be operating alone or may be one of several acting collectively to create a safety zone. Further, it is contemplated that the mobile robot is at a facility (such as an order fulfilment facility 100 described above) with a plurality of pathways 108 and with a guide system (such as the track system described above) for facilitating movement along the plurality of pathways 108. The mobile robot 602 is one of multiple mobile robots configured to move along the pathways 108 at the facility.

[0048] The mobile robot 602 may include various components, such as a locomotion system 604, extendable and retractable member(s) 606, sensor(s) 608, motor(s) 610, a charge assembly 612, a controller 613, and a safety controller 615. The mobile robot 602 includes a locomotion system 604 that interacts with the guide system to facilitate movement along the plurality of pathways108. It also includes an extendable and retractable member 606 that engages a support adjacent to a pathway 108. It is generally contemplated that, when in a blocking position, this member 606 can be extended to lock the mobile robot 602 into the blocking position.

[0049] The system 600 also includes support(s) 614 having receiving portions 616 with the receiving portions 616 receiving the extendable and retractable members 606 of the mobile robots 602. In one form, the support 614 may be the vertical / level changing towers described above or some part thereof. Further, in one form, the extendable and retractable member 606 may include a shaft and the receiving portion 616 may include a channel with the channel receiving the shaft therein. An example of a mobile robot with a shaft / pinion engagement assembly is described further below. The blocking position is established and defined where a receiving portion 616 of a support 614 has received an extendable and retractable member 606 of the mobile robot 602, thereby limiting movement of the mobile robot 602 and blocking other mobile robots from passing along a pathway occupied by the mobile robot 602 at the blocking position.

[0050] The mobile robot 602 may include a sensor 608 to determine proper engagement of member 606 with the receiving portion 616. In one form, the mobile robot 602 may have a sensor 608 for detecting that the extendable and retractable member 606 engages the receiving portion 616 when the extendable and retractable member 606 has been extended from the mobile robot 602 when the mobile robot 602 is located at the blocking position. Further, the sensor 608 may be used to monitor this engagement continually / periodically to make sure the member 606 and receiving portion 616 remain engaged. The sensor 608 may be disposed at any of various locations, such as on the body of the mobile robot 602 or on the extendable and retractable member 606. If the sensor 608 detects that the member 606 and receiving portion 616 are not properly engaged and locked, certain action may be taken, as addressed further below.

[0051] The mobile robot 602 may include multiple extendable and retractable members 606. In one form, the mobile robot 602 may include a second extendable and retractable member 606. The system 600 may include a second support 618 (such as on an opposite portion of a level changing tower from the first support 614) having a second receiving portion 620. In the blocking position, the second receiving portion 620 may receive the second extendable and retractable member 606 of the mobile robot 602. There may also be a second sensor 608 associated with the second extendable and retractable member 606. The use of a second support 618 may provide additional stability to the mobile robot 602 in the blocking position.

[0052] Further, the mobile robot 602 may include motor(s) 610. In one form, it is generally contemplated that the mobile robot 602 may deactivate a motor 610 after it is in the blocking position. Where there are at least two extendable and retractable members 606, there may be a motor 610 associated with extending retracting each member 606. This deactivation may constitute an additional precaution seeking to limit inadvertent movement of the member(s) 606 or of the mobile robot 602 when the mobile robot 602 is at the blocking position.

[0053] The mobile robot 602 may also include a charge assembly 612. In one form, the mobile robot 602 is configured to be electrically charged when in the blocking position by engagement of the charge assembly 612 with a charging portion 622 coupled to a support 614. For example, where there are two supports 614, 618, the first support 614 might have a first charging portion 622, and the second support 618 might have a second charging portion 624. Alternatively, even with the use of two supports 614, 618, there may be only one charging portion. For example, if the two supports 614, 618 are on opposite sides of a level changing tower, each level changing tower may only have one charging portion 622, 624, such as a charging rail, as described below. In one form, it is contemplated that this charging will allow the mobile robot 602 to maintain certain operations at the blocking position, such as communication. Further, the charging may allow the sensor 608 to continue confirming proper engagement of member 606 and receiving portion 616.

[0054] In one form, the charge assembly 612 of the mobile robot 602 may include an onboard rechargeable energy storage device, which may include a bank of supercapacitors. Any of a variety of supercapacitors may be used in the charge assembly 612, including, for example, regular electric double layer capacitors, lithium supercapacitors, and ultra-low impedance capacitors. It is further understood that the charge assembly 612 may be or include a variety of rechargeable power supplies other than supercapacitors in other embodiments, including, for example, ordinary capacitors, electrochemical batteries, and other types of rechargeable power sources. Additional details regarding charge assemblies and charging systems, such as may be used with mobile robots, are described in U.S. Published Patent Application No. 2019 / 0245366, published August 8, 2019, entitled "Opportunistic Charging System for an Automated Storage and Retrieval System", which is incorporated herein by reference in its entirety.

[0055] It is also contemplated that the system 600 may include a control circuit 626 that is configured to perform certain operations. In one form, it is contemplated that the control circuit 626 may be a centralized control circuit that is remote from the mobile robots 602. Further, it iscontemplated that the control circuit 626 may generally be in communication with the various mobile robots 602.

[0056] In this context, the term control circuit 626 refers broadly to any microcontroller, computer, or processor-based device with processor, memory, and programmable input / output peripherals, which is generally designed to govern the operation of other components and devices. It is further understood to include common accompanying accessory devices, including memory, transceivers for communication with other components and devices, etc. These architectural options are well known and understood in the art and require no further description here. The control circuit 626 may be configured (for example, by using corresponding programming stored in a memory as will be well understood by those skilled in the art) to carry out one or more of the steps, actions, and / or functions described herein.

[0057] As shown in FIG. 6, the control circuit 626 may be coupled to a memory 628 and to a network interface 630 and wireless network(s) 632. The memory 628 can, for example, store non- transitorily computer instructions that cause the control circuit 626 to operate as described herein, when the instructions are executed, as is well known in the art. Further, the network interface 630 may enable the control circuit 626 to communicate with other elements (both internal and external to the system). This network interface 630 is well understood in the art. The network interface 630 can communicatively couple the control circuit 626 to the wireless network 632 and whatever other networks 632 may be appropriate for the circumstances. The control circuit 626 may make use of databases, including cloud databases, and / or operate in conjunction with a cloud computing platform. While one control circuit 626 is shown, in some forms, the functionalities of the control circuit 626 may be implemented on a plurality of processor devices communicating on a network 632.

[0058] In some forms, it is contemplated that the control circuit 626, or overall control system, for the order fulfillment facility 100 may include a routing system 627, which may generate and wirelessly transmit destination and travel route information to a robot controller 613 within each of the mobile robots 602. The control circuit 626 may further include a central safety controller, such as a main safety programmable logic controller (MSPLC) 629, which transmits a periodic enabling message, also known as a heartbeat, to a safety controller, or safety PLC 615, on each mobile robot 602. The wireless heartbeat may be an encrypted signal sent to each mobile robot periodically, such as for example every few seconds. If a wireless heartbeat is received, it isdecrypted and verified. The identifier may be checked to confirm it is the next expected identifier in the sequence, and the wireless heartbeat may be checked for data corruption.

[0059] In some forms, if the safety PLC 615 within a mobile robot 602 fails to receive the wireless heartbeat, the verification process fails, or the safety PLC 615 receives a "halt" message from the MSPLC 629, the safety PLC 615 automatically immobilizes the mobile robot 602. In particular, safety PLC 615 may be coupled to the robot locomotion system 604. If anything other than a normal operations heartbeat is received by the safety PLC 615, the safety PLC 615 may shut down the robot locomotion system 604 by executing a Category O stop (safe torque off) or Category 1 stop (safe stop 1) in accordance with IEC 60204-1. In the execution of certain safety protocols, the halt message sent by the MSPLC 629 may be global, i.e., it is sent to all robots, and has the effect of stopping motion of all robots 602 in the order fulfillment facility 100 (e-stopping the system). Further, this global halt message may be transmitted, for example, in response to a notification (such as by a safety PLC 615) or a determination that one of the mobile robots 602 instructed to assume a blocking position (or safe state) at an assigned location is unable to do so or has moved from its blocking position. RFID tags on the mobile robots 602 may be used to confirm their positioning.

[0060] Further, in one form, the control circuit 626 may be configured to: identify a location of a safety zone; instruct mobile robots in the safety zone to leave the safety zone; instruct at least one mobile robot to block at least one access point to the safety zone; and confirm positions of the at least one robot at the at least one access point. The control circuit 626 may be used to provide instructions and commands to mobile robot(s) 602 to create a safety zone. It may also be used to confirm that the mobile robot(s) are at and remain at their blocking positions. The control circuit 626 may be used to implement a blocking arrangement or plan that has been developed by individual(s).

[0061] The control circuit 626 may also be used to develop or create a blocking arrangement or plan. In one form, the control circuit 626 may be further configured to: determine locations of access point(s) to a safety zone, in accordance with a blocking plan; and instruct mobile robot(s) to move to the locations of the access point(s) to enter blocking positions at those locations. In this form, for example, once the control circuit 626 identifies the location of a damaged / incapacitated / non-functional mobile robot, it may define a safety zone about that location, determine access points to that location, determine blocking positions, and determine and instruct mobile robots 602 to move to and occupy those blocking positions.

[0062] In some forms, it is contemplated that the control circuit 626 will confirm or receive confirmation of the positions of the mobile robots 602 at the blocking positions. The control circuit 626 may instruct, or drive, the mobile robots 602 to their respective blocking locations when the control circuit 626 establishes the safety zone. The control circuit 626 may then confirm or receive confirmation that the mobile bots 602 are in their proper blocking locations via positional data. This positioning confirmation may be accomplished in various ways. For example, positional data may be obtained from a mobile robot's motor encoders, which may be used to confirm its location relative to observed fiducials of the mobile robot 602. Additionally, a mobile robot 602 may use its RFID reader(s), camera(s), and / or other devices to establish its position, as alternative or additional levels of positional confirmation.

[0063] An example of an extendable and retractable member of a mobile robot is now described. In one form, it is contemplated that this member may include a pinion that is used to facilitate movement of the mobile robot up and down the level changing towers. More specifically, this pinion engages a rack structure of a level changing tower to ascend and descend the tower. It may also be used to lock a mobile robot into a blocking position.

[0064] In FIG. 7, there is shown a side view of a robot 710. In one form, this robot 710 has drive wheels 712, support wheels 714, guide rollers 716, pinion 718 and counterwheel 719, and counterwheel 720. During an ordinary climbing operation, the pinion 718 and counterwheel 719 and counterwheel 720 selectively engage a rack allowing the robot 710 to climb or descend vertically. While climbing, counterwheel 719 and counterwheel 720 react to the cantilevered weight of robot 710 where force 724 reacts with counterwheel 720 and force 726 reacts with counterwheel 719. Pinion 718 further vertically supports the weight 728 of robot 710.

[0065] In FIG. 8, there is shown a view of pinion 718. In one form, pinion 718, also referred to as a drive gear, has teeth 740 and keyway 742. Teeth 740 preferably have a chamfered lead in portion 744 that is provided to prevent jamming or missed engagement when engaging the rack. Further details regarding the structure and operation of the robot 710 is included in U.S. Published Patent Application No. 2020 / 0087067, which is incorporated by reference herein in its entirety. As used herein, the pinion 718 may constitute part of an extendable and retractable member that engages and is received within a rack structure (which may constitute a receiving portion of a support).

[0066] In FIG. 9, there is shown a partial section view of a mobile robot 710 showing one side for clarity. In the state shown in FIG. 9, lead screw 738 is rotated such that pinion 718 is just about toengage with rack 782. In the relative position between spline 1 1 and shaft 722 shown in FIG. 9, there is rotational play between spline 1T1 and shaft 722 such that pinion 718 can freely engage rack 782. In FIG. 10, lead screw 738 is rotated such that pinion 718 is fully engaged with rack 782.

[0067] FIG. 11 shows the mobile robot 710 on an aisle 784 and at a level changing tower 786.Much of the detail has been removed so as just to show the mobile robot 710, aisles 784 formed by two rails, and two supports of the level changing tower 786. The mobile robot 710 may engage the level changing tower 786 to assume a blocking position. The pinion 718 may be extended to engage and be received in the rack 782. Although only one side is shown in FIG. 11, a second pinion on the other side of the mobile robot 710 is extended to engage a second rack.

[0068] Although the use of extendable and retractable pinions have been described above, it is also contemplated that, in certain forms, alternative blocking devices and methods may be used. Other types of extendable members may be used to engage supports at the facility. Further, in some forms, besides or in addition to extending shaft(s), the mobile robot might also park at its blocking location and observe movement of its wheels using alternative safety rated sensor(s). The mobile robot may confirm that its wheels remain stationary. If the alternative safety rated sensor(s) detect movement, for example, this detection might trigger an e-stop of the system.

[0069] Next, an example of a charging portion of a support is shown. FIG. 12 illustrates a perspective view of a section of a track system 816 within an aisle 808. The track system 816 comprises horizontal rails 818 and level changing towers 820 (enclosed within dashed lines). Storage locations (not shown in FIG. 12) would be positioned adjacent the track system 816, on opposed sides of the aisle 808 location. The decks 812 allow travel of mobile robots 850 between and into the aisles 808 at different levels of the storage structure.

[0070] In one form, a charge rail 830 may be incorporated into the vertical track on one or both sides of a level changing tower 820. Charge rail 830 may be electrically coupled to a facility power source 832 so as to receive the voltage from the facility power source 832. In some forms, the voltage received in each of the one or more charge rails 830 may be an AC voltage, at for example 120 V, 220 V, or 240 V. It is understood that facility power source may provide other AC voltages in other forms. Additionally, a voltage converter may be provided between the facility power source 832 and charge rail 830 to convert the voltage to DC voltage, or a voltage which is different than the facility power source 832. Further details regarding charge rails and systems, such as may be used with mobile robots, are described in U.S. Published Patent Application No. 2019 / 0245366, which was previously mentioned and is incorporated herein by reference in its entirety.

[0071] FIG. 13 shows a process 900 for using mobile robots to create safety zones at facilities. It is generally contemplated that the process 900 may involve some or all of the components of the facility 100 and may involve some or all of the features of the mobile robot blocking system 600. The above descriptions of the facility 100, mobile robot blocking system 600, and other features and components are generally incorporated herein.

[0072] At block 902, mobile robots are provided that move about a facility. The mobile robots move along pathways at the facility with a guide system for facilitating their movement along the pathways, such as aisles. Each of the mobile robots may include various components, such as a locomotion system for cooperating with the guide system, extendable and retractable member(s) for engaging support(s) adjacent to a pathway, sensor(s) for detecting that the extendable and retractable member(s) engage receiving portion(s), motor(s), charge assembl(ies) for electrically charging the mobile robot, a controller, and a safety PLC.

[0073] At block 904, supports are provided with receiving portions. It is generally contemplated that the receiving portions are configured to receive the extendable and retractable members of the mobile robots. In one form, it is contemplated that these supports may be part of level changing towers that mobile robots may use at the facility to ascend and descend to different levels. Also, in one form, the extendable and retractable member(s) may include shafts and / or pinions that are received in channels, such as in rack structures.

[0074] At block 906, extendable and retractable member(s) of a mobile robot are receiving in receiving portions. It is generally contemplated that, when this action occurs, the mobile robot is assuming a blocking position in a pathway. At block 908, when at the blocking position, the mobile robot limits the movement of itself and blocks other mobile robots from passing along the pathway occupied by the mobile robot.

[0075] The mobile robot may take additional action, while at the blocking position. At block 910, the mobile robot may electrically charge itself when in the blocking position by engagement of a charge assembly of the mobile robot with a charging portion coupled to a support. This charging helps ensure that it can still perform certain operations while in the blocking position, such as communication with a control circuit that is remote from the mobile robot and such as using sensor(s) to confirm that it remains engaged with the support(s). At block 912, motor(s) of the mobile robot may be deactivated at the blocking position. For example, these motor(s) may be for locomotion of the mobile robot itself and / or motors associated with movement of the extendable and retractable member(s).

[0076] It is also contemplated that, in some forms, mobile robots may receive instructions from a control circuit that is remote from them. At block 914, mobile robots(s) may be instructed to block access point(s) and the positions of the mobile robot(s) may be confirmed. In one form, a control circuit may: identify a location of a safety zone; instruct mobile robots in the safety zone to leave the safety zone; instruct at least one mobile robot to block at least one access point to the safety zone; and confirm positions of the at least one robot at the at least one access point. It is generally contemplated that the positions of the mobile robots may be confirmed in different ways, such as, for example, by communication from the mobile robots and various types of positioning detection and location systems (such as GPS).

[0077] At block 916, locations of access points to a safety zone and a blocking plan may be determined. In one form, it is contemplated that one or more individuals may determine the locations of the access points pursuant to a blocking plan determined by those individuals. The individuals may also utilize a control circuit to provide instructions to the mobile robots(s) and to confirm their positions. In another form, however, it is also contemplated that the control circuit may determine the blocking plan. For example, in this form, the control circuit may itself determine locations of access points to the safety zone, in accordance with a blocking plan and may instruct mobile robots to move to the locations of the access points to enter blocking positions at those locations.

[0078] FIG. 14 shows another process 1000 for using mobile robots to create safety zones at facilities. FIG. 14 shows certain actors / entities and their actions or operations with respect to the process 1000. More specifically, it shows actions / operations by a technician 1002, the outer barrier 1004, robots 1006, a routing system 1008, a main safety programmable logic controller (MSPLC) 1010 (part of the control circuit), and catwalks 1012. It is generally contemplated that the process 1000 may involve some or all of the components of the facility 100 and may involve some or all of the features of the mobile robot blocking system 600. The above descriptions of the facility 100, mobile robot blocking system 600, and other features and components are generally incorporated herein.

[0079] At block 1014, a technician 1002 selects a safety zone. It is generally contemplated that the technician 1002 has been informed of a damaged or incapacitated robot. Further, he or she has determined a blocking plan in which certain access points to the damaged or incapacitated robot will be blocked. As stated above, in some forms, a control circuit may be used to determine the blocking plan and to select the safety zone.

[0080] At block 1016, the technician 1002 may communicate this safety zone to a routing system 1008, which routes the mobile robots. In some forms, this routing system 1008 may be part of the overall control circuit. In some forms, the routing system 1008 instructs the robots 1006 to move to outer ends of the safety zone and changes their designation to barrier robots 1006. Some of these robots 1006 may travel from inside the safety zone, while others may travel from outside the safety zone.

[0081] At block 1018, the barrier robots 1006 extend their pinions to engage one or more supports on the side(s) of the aisle(s). In some forms, it is contemplated that once the barrier robots 1006 are localized, i.e., at their assigned position, they will report this status to the MSPLC 1010. In some forms, it is contemplated that the barrier robots 1006 each have at least one safety sensor to confirm engagement of the pinions and to monitor continued engagement. In some forms, there may be a safety sensor coupled to each pinion to monitor its engagement, such as, for example, two safety sensors for two pinions. Further, once the one or more pinions are engaged, the barrier robot 1006 may report its localization, i.e., that it is in the blocking position, to the MSPLC 1010.

[0082] At block 1020, the MSPLC monitors and confirms certain operations regarding the barrier robots 1006. It is generally contemplated that the MSPLC 1010 is part of the control circuit that governs operation of the system. In some forms, it may monitor and confirm the locations of the barrier robots 1006. In some forms, it may monitor and confirm that all of the barrier robots 1006 have their pinion(s) extended and may monitor pinion status, such as via the safety sensor(s) and safety PLCs of the barrier robots 1006. In other words, it confirms that they are in the blocking positions (safe states). In some forms, the safety PLC of each barrier robot may place the locomotion system in a safe torque off (STO) setting, and each barrier robot is preferably being electrically charged while in the blocking position. If safety rated sensor(s) in the mobile robots detect inadvertent movement, the entire system may be e-stopped.

[0083] At block 1022, in some forms, the MSPLC 1010 confirms that all of the robots 1006 are outside of the safety zone. It may have confirmed the positions of the barrier robots 1006 but it also confirms that the non-barrier robots 1006 are outside of the safety zone. At block 1024, any non-barrier robots 1006 that are in the safety zone are evacuated, i.e., instructed to leave, the safety zone.

[0084] At block 1026, in some forms, the MSPLC 1010 validates that the safety zone is in place. It validates that the barrier and non-barrier robots 1006 are in proper locations, and the barrierrobots 1006 are in blocking positions. At block 1028, the routing system 1008 is instructed so as not to direct any robots to enter the safety zone. The MSPLC 1010 also validates the status of catwalks 1012.

[0085] At block 1026 (or at block 1022), it is contemplated that the MSPLC 1010 may confirm or receive confirmation of the positions of the barrier robots 1006 at the blocking positions. The MSPLC 1010 may confirm or receive confirmation that the barrier robots 1006 are in their proper blocking locations via positional data. This positioning confirmation may be accomplished in various ways. For example, positional data may be obtained from a barrier robot's motor encoders, which may be used to confirm its location relative to observed fiducials of the barrier robot 1006. Additionally, a barrier robot 1006 may use its RFID reader(s), camera(s), and / or other devices to establish its position, as alternative or additional levels of positional confirmation.

[0086] At block 1030, in some forms, catwalks 1012 in the area of the safety zone have been closed. These catwalks 1012 are closed to prevent access to the safety zone area via mobile robots 1006 that may be ascending or descending in the level changing towers. In some forms, it is contemplated that catwalks 1012 in the remainder of the facility will remain open, which allows operations to continue generally in much of the rest of the facility outside of the safety zone area.

[0087] At block 1032, after the safety zone has been validated, the outer barrier(s) 1004 are opened. At this stage, the MSPLC 1010 has confirmed creation of the safety zone by confirming the positions of the robots 1006, confirming that the barrier robots 1006 are in blocking positions, and confirming that catwalks 1012 in the area of the safety zone have been closed. At this stage, it is safe for a technician 1002 to enter the safety zone to check and handle the damaged or incapacitated robot 1006. At block 1034, the technician 1002 enters the safety zone.

[0088] At block 1036, the technician 1002 performs his or her tasks. In some instances, the tasks may involve investigating the damaged or incapacitated robot 1006, diagnosing the general nature of the issue, and determining how to address the issue. In some instances, the tasks may further include repairing the robot 1006 in the safety zone or removing the robot 1006 to a more secure location, such as, for example, beyond the outer barrier 1004 (where the technician 1002 may have entered the safety zone). At block 1038, upon completion of these tasks, the technician 1002 exits the safety zone.

[0089] At block 1040, after the technician 1002 exits the safety zone, the outer barrier(s) 1004 close. Now, the system is ready to resume its normal operational status. At block 1042, theMSPLC 1010 may determine that the outer barrier 1004 is closed. It may change an indicator from a temporary inner barrier status to a standard outer barrier status.

[0090] At block 1044, the MSPLC 1010 resets the safety zone status such that it is no longer designated as a safety zone. Instead, it is an area of the facility that can again be accessed by robots 1006, and this area can resume normal operations. The MSPLC 1010 activates the barrier robots 1006 so that they can leave their blocking positions and resume their normal operations. At block 1046, the routing system 1008 transitions the barrier robots 1006 back to production robots 1006 and allows routing throughout the system. At block 1048, the barrier robots 1006 resume ordinary operation. At block 1050, the catwalks 1012 that were in the former safety zone area are opened. Robots 1006 can ascend and descend level changing towers in the area of the former safety zone area.

[0091] Those skilled in the art will recognize that a wide variety of other modifications, alterations, and combinations can also be made with respect to the above-described embodiments without departing from the scope of the invention, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept.

Claims

Claims1. A mobile robot blocking system to create safety zones at facilities, the system comprising: a facility with a plurality of pathways and with a guide system for facilitating movement along the plurality of pathways; a plurality of mobile robots configured to move along the plurality of pathways at the facility, each mobile robot comprising: a locomotion system configured to cooperate with the guide system to facilitate movement of each mobile robot along the plurality of pathways; an extendable and retractable member configured to engage a support adjacent to a pathway; a plurality of supports with receiving portions, the receiving portions configured to receive the extendable and retractable members of the mobile robots; and wherein a blocking position is defined where a receiving portion has received an extendable and retractable member of a mobile robot, thereby limiting movement of the mobile robot and blocking other mobile robots from passing along a pathway occupied by the mobile robot at the blocking position.

2. The system of claim 1 wherein: the facility comprises an order fulfillment facility including a plurality of storage locations configured to store containers containing goods, each storage location being accessible by a pathway; and the plurality of mobile robots are configured to access the plurality of storage locations to deposit or retrieve containers at the plurality of storage locations.

3. The system of claim 1, wherein each mobile robot has a sensor configured to detect that the extendable and retractable member engages the receiving portion, when the extendable and retractable member has been extended from the mobile robot when the mobile robot is located at the blocking position.

4. The system of claim 1, wherein the guide system comprises: a track with at least one rail for engagement by the locomotion system of each mobile robot; and / or guidelines disposed in the pathways to facilitate navigation by each mobile robot.

5. The system of claim 1, wherein the extendable and retractable member comprises a shaft and the receiving portion comprises a channel, the channel configured to receive the shaft therein.

6. The system of claim 1, wherein: the mobile robot comprises a second extendable and retractable member; and in the blocking position, a second receiving portion has received the second extendable and retractable member of the mobile robot.

7. The system of claim 1, wherein the mobile robot is configured to be electrically charged when in the blocking position by engagement of a charge assembly of the mobile robot with a charging portion coupled to a support.

8. The system of claim 1, wherein the mobile robot further comprises a motor, and wherein the mobile robot deactivates the motor after it is in the blocking position.

9. The system of claim 1, further comprising a control circuit configured to: identify a location of a safety zone; instruct mobile robots in the safety zone to leave the safety zone; instruct at least one mobile robot to block at least one access point to the safety zone; and confirm positions of the at least one robot at the at least one access point.

10. The system of claim 9, wherein the control circuit is further configured to: determine locations of a plurality of access points to the safety zone, in accordance with a blocking plan; and instruct a plurality of mobile robots to move to the locations of the plurality of access points to enter blocking positions at those locations.

11. A method of using mobile robots to create safety zones at facilities, the method comprising: providing a plurality of mobile robots configured to move along a plurality of pathways at a facility and with a guide system for facilitating movement along the plurality of pathways, each mobile robot comprising:a locomotion system configured to cooperate with the guide system to facilitate movement of each mobile robot along the plurality of pathways; an extendable and retractable member configured to engage a support adjacent to a pathway; providing a plurality of supports with receiving portions, the receiving portions configured to receive the extendable and retractable members of the mobile robots; and at a blocking position, receiving, in a receiving portion, an extendable and retractable member of a mobile robot; and at the blocking position, limiting movement of the mobile robot and blocking other mobile robots from passing along a pathway occupied by the mobile robot at the blocking position.

12. The method of claim 11 wherein: the facility comprises an order fulfillment facility including a plurality of storage locations configured to store containers containing goods, each storage location being accessible by a pathway; and the plurality of mobile robots are configured to access the plurality of storage locations to deposit or retrieve containers at the plurality of storage locations.

13. The method of claim 11, further comprising: by a sensor of the mobile robot, detecting that the extendable and retractable member engaged the receiving portion, when the extendable and retractable member has been extended from the mobile robot and when the mobile robot is located at the blocking position.

14. The method of claim 11, wherein the guide system comprises: a track with at least one rail for engagement by the locomotion system of each mobile robot; and / or guidelines disposed in the pathways to facilitate navigation by each mobile robot.

15. The method of claim 11, wherein the extendable and retractable member comprises a shaft and the receiving portion comprises a channel, the channel configured to receive the shaft therein.

16. The method of claim 11, wherein the mobile robot comprises a second extendable and retractable member, the method further comprising:in the blocking position, receiving, by a second receiving portion, the second extendable and retractable member of the mobile robot.

17. The method of claim 11, further comprising: electrically charging the mobile robot when in the blocking position by engagement of a charge assembly of the mobile robot with a charging portion coupled to a support.

18. The method of claim 11, wherein the mobile robot further comprises a motor, the method further comprising: deactivating the motor after the mobile robot is in the blocking position.

19. The method of claim 11, further comprising, by a control circuit: identifying a location of a safety zone; instructing mobile robots in the safety zone to leave the safety zone; instructing at least one mobile robot to block at least one access point to the safety zone; and confirming positions of the at least one robot at the at least one access point.

20. The method of claim 19, further comprising, by the control circuit: determining locations of a plurality of access points to the safety zone, in accordance with a blocking plan; and instructing a plurality of mobile robots to move to the locations of the plurality of access points to enter blocking positions at those locations.

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