Mobile robot-on-rail, and related systems and methods

A robot system includes a track that extends along an axis between a first location and a second location. The track includes a pair of rails and a power transmitter and a radiating cable each extending along the track. A carriage is configured to convey a robot arm along the track. The carriage includes a plurality of wheels configured to roll along the pair of rails, a motor configured to drive at least one of the wheels along one of the rails, a power collector configured to translate along the power transmitter while maintaining contact with the power transmitter so as to conduct electrical power from the power transmitter to the motor, and a transceiver configured to receive and send electronic information from and to the radiating cable.

BACKGROUND

The present invention relates to automation, and more particularly to systems for enhanced-motion robots.

The robotics field has developed many tools for engaging and lifting (i.e., “picking”) items at the end of a robotic arm. Robotic arms are typically mounted to a static or substantially static robot station and have various sections and joints providing the arm with movement capabilities along and/or about up to six axes of movement (thus, such robotic arms are commonly referred to as a “6-axis” robot or robotic arm). While the foregoing degrees of movement allow the robotic arm to articulate its end effector as needed to pick, transport, and deposit items from a stationary picking station in a warehouse (such as an order fulfillment center), the robotic arm is limited in many ways by operating from a static robot station.

Providing the robot arm mobility along an additional axis (such as a seventh axis) would increase the robot arm's range of motion and thus its effectiveness transporting items in a warehouse.

DETAILED DESCRIPTION

The embodiments of the present disclosure pertain to mobile robots that have a robot arm, such as a type configured to articulate along and/or about six axes of movement, which robots are mounted to a carriage that moves along a track, which provides the robot with movement along an additional axis, such as a seventh axis. Such mobile robots can be referred to as “robot-on-rail” units. Because these mobile robots travel between various locations along the track, they provide enhanced flexibility in sorting operations in a fulfilment center, which can provide significant increases in sorting efficiency and throughput. Additionally, the mobile robots disclosed herein are powered and controlled without the use of cables that would physically tether the robots to a fixed power source. The absence of tethering cables is expected to provide significant reductions to the maintenance time and cost of the systems that employ these mobile robots. When employed at industrial scales, such as within a network of fulfilment centers, the cost benefits provided by the increased sorting throughput and reduced maintenance costs can be substantial.

Referring now toFIG.1, a mobile robot system2includes a robot4mounted to a carriage60that is configured to travel along a track10between a first position10aalong the track10and a second position10balong the track10. The track10extends along an axis12, which can also be referred to as an “axis of travel”, between a first track end11aand a second track end11bopposite each other along the axis12. The axis12extends along at least a first direction X, which can be a purely horizontal dimension. It should be appreciated, however, that the axis12can also extend along a second direction Y, such as a horizontal dimension perpendicular to the first dimension X, and/or a third direction Z, such as a vertical dimension perpendicular to the first and second dimensions X, Y. Thus, although the axis of travel12depicted in the Figures extends linearly along a single horizontal direction, it should be appreciated that the axis12can extend along one, two, or three dimensions as desired. In the embodiments illustrated herein, the first and second directions X, Y are horizontal directions, while the third direction Z is a vertical direction, although other respective orientations are within the scope of the present disclosure. It is to be appreciated that when the third direction is the vertical direction Z, the vertical direction Z is bi-directional, and has constituent mono-direction components including the downward vertical direction ZD and the opposite, upward vertical direction ZU.

The first and second positions10a,10balong the track10are preferably intermediate the first and second track ends11a,11b, such that the first position10ais spaced from the first track end11a, and the second position10bis spaced from the second track end11b. The system2includes a first staging region13aalongside the first position10aof the track10, a second staging region13balongside the second position10bof the track10, and one or more optional additional staging regions13nalongside the track10, as needed. It is to be appreciated that any of the staging regions can be located along either side of the track10, as needed.

The track10and the staging regions13a-ncan be contained within a divider6or “fence”, which can circumscribe an area in which the mobile robot4operates, which area can be referred to as a “robotic work cell”7or simply a “work cell”7. The divider6can include one or more gates8for entry and exit of operators, such as other mobile robots and/or human operators, to and from the work cell7. It is to be appreciated that items for picking or other sortation can enter and exit the work cell7through one or more additional openings in the divider. Additionally or alternatively, items can enter and exit the work cell7via mechanical conveyance that extends above the divider and into the work cell7and/or through an opening in a floor9of the work cell7.

In one non-limiting example, the robot4can be a Fanuc Series R2000/125L six-axis robot manufactured by Fanuc America Corporation of Rochester Hills, Mich. It is to be appreciated, however, that other robots4can be employed with the carriage60described herein.

Referring now toFIGS.2A through2C, the track10includes a first rail14aand a second rail14brunning parallel with each other and spaced from each other along the second direction Y. The first and second rails14a,14bcan be referred to as “primary rails.” The track10also includes an auxiliary linkage16extending along the axis12and positioned intermediate the first and second rails14a,14b. The auxiliary linkage16includes supporting components for supplying power and data transmission to the carriage60. As used herein, the term “data” means “electronic information.” For example, the power supply and data transmission of the auxiliary linkage16can be provided by a power transmitter18and a communication device20, respectively. The power transmitter18and the communication device20can each be elongate along the first direction X and thus parallel with the axis12. The auxiliary linkage16can also be referred to as an “auxiliary rail” or “third rail”16. It is to be appreciated that in the illustrated embodiments, the power transmitter18and the communication device20are each stationary elements of the mobile robot system2

The track10can also include a first end-stop19aand a second end stop19badjacent the first and second track ends11a,11b, respectively. Each end stop19a,19bcan include a fixed member21and a contact member23configured to abut a portion of the carriage60and move relative to the fixed member21in a manner arresting momentum of the carriage60should the carriage60abut the contact member23. In the illustrated embodiment, the fixed member21is a cylinder and the fixed member23is a piston configured to translate against a compliant element within the cylinder, such as a spring or a dissipative fluid, such as a hydraulic or pneumatic fluid, by way of non-limiting examples. It is to be appreciated that other end stop configurations are within the scope of the present disclosure. Additionally, although the end stops19a,19bare shown as being positioned between the first and second rails14a,14b, the end stops19a,19bcan optionally be located outside the rails14a,14bin other embodiments. A travel distance D1provided by the track10can be measured between the contact members23along the first direction X. The travel distance D1can be any distance as necessary for an item moving process in a warehouse, such as less than 1 ft., from 1 ft. to 10 ft., from 10 ft. to 25 ft., from 25 ft. to 50 ft., from 50 ft. to 100 ft., or greater than 100 ft., as needed. It is to be appreciated that the embodiments disclosed herein can be employed to provide a track10of virtually any length within a warehouse.

With reference toFIG.2A, the carriage60includes a plurality of wheels62configured to travel along the rails14a,14b. In particular, the carriage60has a first side60aand a second side60bspaced from each other along the second direction Y, such that the first side60ais configured to be proximate the first rail14aand remote from the second rail14b, while the second side60bis configured to be proximate the second rail14aand remote from the first rail14b. Each of the first and second sides60a,60bof the carriage60has one or more wheels62extending therefrom and configured to run along the respective rail14a,14b. The carriage60also has a first end60cand a second end60dspaced from each other along the axis12.

The carriage60also includes a drive assembly64configured to drive at least one of the wheels62along its respective rail14a,14b, and a carriage power assembly66configured to communicate power from the power transmitter18to the drive assembly64. The carriage60also includes a carriage control module68(which can also be referred to as a “robot controller unit” or simply a “controller”) that houses a processor70configured to receive data from a system control unit100. Such data can include robot control data for controlling operation of the robot4, such as for picking items, as well as carriage control data for controlling movement of the carriage60along the track10, such as for positioning the robot4adjacent selective staging regions13a,13b,13n. In particular, the carriage control module68is preferably in electronic communication with a carriage transceiver72that is positioned on the carriage60and is configured to receive and send data through the communication device20of the auxiliary rail16, which is in electronic communication with the system control unit100. It is to be appreciated that the system control unit100is preferably integrated within a warehouse control system for governing large-scale operations within the warehouse, such as inventory, picking, routing/conveying, sorting, packaging, and/or staging of items within the warehouse.

With reference toFIGS.2B and2C, the first and second rails14a,14band the auxiliary rail16can be supported by a series of support members22anchored to the floor9by a plurality of anchors24. Alternatively, the rails14a,14b, and16can be anchored directly to the floor9. The support members22can be cross-beams (also referred to as “sleepers”) elongate along the second direction Y. The support members22are preferably attached to each anchor24at an adjustable distance Z1along the vertical direction Z. In this manner, distance Z1for each support member22along the track10can be uniform, allowing each support member22to be elevated above the floor9at a uniform distance, which can enhance the stability of the track10and the carriage60during operation. In such embodiments, the support members22can be referred to as “support standards” or simply “standards.” Such embodiments are preferred for effectively insulating the rails14a,14b,16from uneven or worn portions of the floor9, and/or as a more direct means of verifying and adjusting the elevation of the support members22as necessary over the operational life of the system2.

Each of the first and second rails14a,14bcan comprise a series of respective rail segments26a,26bcoupled in succession along the first direction X. Each of the first and second rails14a,14bincludes a running portion30along which the wheels travel62, a mount portion32configured to be anchored to the support members22(or alternatively directly to the floor9), and an extension portion34extending between the running portion30and the mounting portion32. It is to be appreciated that the running portion30can also be referred to as a “head”30of the respective rail14a,14b; the mounting portion32can also be referred to as a “foot”32of the respective rail14a,14b; and the extension portion34can also be referred to as a “web”34of the respective rail14a,14b. One or more an up to all of the rail segments26a,26bcan be a monolithic member that defines its respective head30, foot32, and web34. In such embodiments, the head30, foot32, and web34can be formed in the monolithic rail segment26a,26bby one or more mechanical bending processes, such as in a bending machine using dies to bend the rail segment26a,26bto its desired shape. Alternatively, one or more of the head30, foot32, and web34of a respective rail segment26a,26bcan be a separate member fastened to one or more of the other members30,32,34of the respective rail segment26a,26b. In yet other embodiments, one or both of the rails14a,14bcan be defined by a single-piece member that defines the head30, foot32, and web34of the respective rail14a,14band extends continuously from the first end11ato the second end11bof the track10.

The head30of each rail14a,14bdefines a primary surface30aconfigured for primary, load-bearing wheels62aof the carriage60to travel along, as well as a secondary surface30bconfigured for secondary, or “upstop” wheels62bof the carriage60to travel along. The primary surfaces30agenerally face upward with respect to the vertical direction Z, and the secondary surfaces30bgenerally face downward with respect to the vertical direction Z. The primary surfaces30aare configured to oppose and thus support against and primary loads imparted by the carriage60and the robot4mounted thereon, which primary loads include the weight of the carriage60and the robot4mounted thereon. The secondary surfaces30bare configured to oppose and thus support against and secondary loads imparted by the carriage60and the robot4mounted thereon, which secondary loads include bending moment forces having directional components in the upward vertical direction ZU, which forces can cause the carriage60(with the robot4mounted thereon) to tip or otherwise disengage from the rails14a,14b. These secondary surfaces30band thus important for the functionality of the system2, as a robot4with a heavy, long arm articulating about the carriage in the second direction Y can otherwise cause the carriage60to tip or disengage from the rails14a,14b.

One or both of the primary rails14a,14bcan also include one or more buttress members35configured to reinforce the rail14a,14bagainst operational forces applied from the carriage60to the primary rails14a,14b, particularly against bending moment forces measured along the second direction Y. Each buttress member35can be configured to provide support to the respective rail14a,14balong the second direction Y. In the illustrated embodiment, each buttress member35can extend from the foot32to the head30(or to a location of the web34adjacent the head30) of the rail14a,14b. The one or more buttress members35can include a plurality of buttress members35affixed to the rails sequentially along the track10, or can optionally include a single, monolithic member35extending between the first and second ends11a,11bof the track10. The one or more buttress members35can include cutouts for reducing the overall weight of the one or more buttress members35, as well as for conserving the material of the buttress member(s)35.

The head30of at least one of the first and second rails14bincludes a guide member36for directing motion of the primary and/or secondary wheels62a,62balong the respective side60a,60bof the carriage60along the first direction X. As shown in the illustrated example, the head30of the first rail14acan define substantially flat primary and secondary surfaces30a,30b, while the head30of the second rail14b, and thus also the primary and secondary surfaces30a,30bthereof, can define the guide member36, which in the present example has an inverted V-shape, as viewed in a sectional plane oriented orthogonal to the axis12. The guide member36can be formed by bending the head30of the second rail14binto the inverted V-shape, although other methods of providing the shape of the guide member36are within the scope of the present disclosure. The wheels62at the side60a,60bof the carriage60corresponding to the guide member36(i.e., the second side60bin the illustrated embodiment) can have geometries complimentary with the guide member36, as described in more detail below.

With reference toFIG.2C, the track10can define a gauge width W (also referred to simply as the “gauge” W), measured between respective innermost points38a,38bof the first and second rails14a,14balong the second direction Y. In some embodiments, the gauge W can be in a range from 12 inches to about 48 inches. Additionally, each rail14a,14bcan have a thickness Tin a range of about 0.125 inches to about 0.75 inches, by way of non-limiting example. The thickness T is preferably substantially equivalent for the first and second rails14a,14b. The thickness T can be measured at the head30, and can be substantially equivalent at the web34and/or the foot32of each rail14a,14bas well. Alternatively, the thickness can vary between the head30and the web34and/or the foot32of each rail14a,14b. It is to be appreciated that the foregoing dimensions of the rails14a,14bcan be scaled upward or downward in size as necessary.

As shown inFIGS.2B and2C, the auxiliary rail16can include a plurality of mounts, such as brackets17, which can be L-shaped and have a first portion17afor anchoring to one of the support members22(or alternatively for anchoring directly to the floor9) and a second portion17bat a right angle to the first portion17a. The second portion17bof each bracket17can carry the power transmitter18and the communication device20. It is to be appreciated that, in other embodiments, the power transmitter18and the communication device20can be carried by different auxiliary linkages or members.

The power transmitter18of the auxiliary rail16is preferably configured for power transmission to the carriage60via translational or “sliding” contact or engagement between the power transmitter18and electrical contacts of the carriage power assembly66. In the illustrated embodiment, the power transmitter18is a bus bar40extending along the auxiliary rail16. The bus bar40has at least one conductive strip of material41configured to conduct current to the carriage60.

Referring now toFIG.3, the bus bar40preferably has a plurality of conductive strips of material41a-d(also referred to herein as “conductive strips”41a-d), such as copper or another conductive material, extending along the first direction X between the first and second ends11a,11bof the track10. The conductive strips41a-dare configured for sliding engagement with contacts of the carriage power assembly66, as described in more detail below. The bus bar40can include a housing42that is attached to the second portions17bof the brackets17along the track10and houses the conductive strips41a-d. One or more and preferably all of the conductive strips41a-dresides in an interior space44defined by an insulative (i.e., non-conductive) support member43, which can also define an opening45in communication with the interior space44. Preferably, the openings45of the bus bar40are slightly narrower than the respective interior spaces44, which can protect against inadvertent physical contact and electrical conduction between the conductive strips41a-dand elements of the system exterior of the bus bar40. It is to be appreciated that the insulative support members43can also be compliant in at least one direction, and preferably in multiple directions, so as to bias the conductive strips41a-dagainst the associated contact members of the carriage60as the carriage60travels along the track10. Such compliance can also accommodate slight variations in the travel of the contact members, such as variations caused by bumps or other travel anomalies experienced by the carriage60, without causing damage to the bus bar40or the contact members.

Additionally, the communication device20carried by the auxiliary rail16is configured for data transmission to and from the carriage60without communication wires physically tethering the carriage60to any portion of the system remote from the carriage60and robot4, such as to the track10. In the illustrated embodiment, the communication device20is a radiating cable50attached to cable mounts52on the second portions17bof the brackets17of the auxiliary rail16. The radiating cable50is preferably a co-axial cable50having an outer conductor that has gaps or slots defined therein, which gaps or slots allow for electronic signal, such as radio waves, to transmit into and out of the cable50along its length (as opposed to the electronic signal transmitting into and out of the cable50solely at one or more of its end nodes). Such radiating cables50are also referred to in other arts, such as subterranean mining arts, as “leaky feeder”; “leaky coaxial cable”; or “leaky coax”.

Referring again toFIG.2A, the radiating cable50is electronically connected to a communication control unit55that is configured to transmit electronic information through the radiating cable50to the carriage control module68. The communication control unit55can also be referred to as an “access point” of the radiating cable50. As with the radiating cable50, the communication control unit55is a stationary element of the mobile robot system2. The communication control unit55includes a signal generator for transmitting electronic signals through the radiating cable50. In particular, the communication control unit55can include a radio frequency (RF) signal generator for transmitting radio waves through the radiating cable50to be received by the carriage transceiver72, which in this embodiment is a radio antenna. The carriage transceiver72then transmits the electronic information in the radio waves to the carriage control module68. It is to be appreciated that the carriage transceiver72is also configured to send electronic information, such as in the form of radio waves, from the carriage control module68, through the radiating cable50, and to the communication control unit55, which is configured to interpret the electronic information received from the carriage transceiver72. Thus, the communication control unit55and the carriage control module68are each configured for two-way communication with each other via the radiating cable50. Thus, the communication control unit55can also be characterized as a transceiver. The inventors are not aware of any radiating cables50or such systems employed for use with prior art mobile robots, particularly track/rail mobile robots, in a fulfilment center.

The radiating cable50can be configured to operate at various frequencies, as desired. For example, the radiating cable50can be configured to operate at Wi-Fi frequencies, such as frequencies within the 2.4 GHz band (i.e., in a range from 2.4 GHz to 2.5 GHz) and/or within the 5 GHz band (i.e., in a range from 5.0 GHz to 5.9 GHz). Moreover, the radiating cable50can be configured to operate at any channel within the 2.4 GHz band or the 5 GHz band, including channel hopping within these bands. In other embodiments, the radiating cable50can be configured to operate at cellular frequencies, such as the 800 MHz band and/or the 1900 MHz band, for example. In yet other embodiments, the radiating cable50can be configured to operate at Zigbee frequencies. It is to be appreciated that the foregoing frequencies are provided as non-limiting examples of the frequencies at which the radiating cable50can be configured to operate, and other frequencies of operation are within the scope of the present disclosure.

The radiating cable50configured as described herein can provide the system2with sufficient wireless data transmission speeds and bandwidths between the track10and the carriage60, even at the maximum carriage60speeds envisioned for the present embodiments, to provide the carriage60, and the robot4mounted thereon, with precise motion control for picking and/or otherwise moving items between locations alongside the track10, such as the staging regions13a,13b,13n.

It is also to be appreciated that in other embodiments, one or both of the carriage60and the robot4can communicate with the system control unit100via wireless data transmission, such as Wi-Fi, wireless local area network (WLAN), and/or wireless radio transmissions, by way of non-limiting examples.

Referring now toFIGS.4A through5C, the carriage60is shown without the robot4mounted thereon for illustrative purposes. The carriage60includes a mounting feature, such as a mounting platform61, on which the robot4can be mounted. As described above, each of the first and second sides60a,60bof the carriage60has one or more wheels62extending therefrom. The wheels62include the primary wheels62aconfigured to travel along the primary surfaces30aof the rails14a,14b, and the upstop wheels62bconfigured to travel along the secondary surfaces30bof the rails14a,14b. In the illustrated embodiment, a single pair of wheels62, including a primary wheel62aand an upstop wheel62b, extends from the first side60aof the carriage60and is configured to travel along the first rail14a, while two pairs of wheels62, each such pair including a primary and upstop wheel62a,62b, extend from the second side60bof the carriage60and are configured to travel along the second rail14b. It should be appreciated, however, that other wheel pairings and configurations are within the scope of the present disclosure. The wheels62can be constructed of a material configured to satisfactorily grip the rails14a,14bfor rapid starting and stopping. Such a wheel material can include a urethane, such as polyurethane, although other wheel materials are within the scope of the present disclosure.

With reference toFIGS.4A through4D, in the illustrated embodiment, the primary wheel62aon the first side60aof the carriage60is a drive wheel62x, and is thus operatively coupled to the drive assembly64of the carriage60. The drive assembly64includes a motor76having a rotor operatively coupled to the drive wheel60x. The motor76is preferably a servo motor configured to precisely control the rotation and angular position of the rotor. In one non-limiting example, the servo motor can be a Fanuc Single Alpha iS (αiS) Series (400V) servo motor manufactured by Fanuc America Corporation. It is to be appreciated, however, that other servo motors76can be employed with the embodiments of the present disclosure.

The drive assembly64preferably includes a drive transmission80that includes a plurality of gears intermeshed with each other and located in a gearbox82. The gears include an input gear coupled to the rotor, and an output gear coupled to the drive wheel62x. The gears of the drive transmission80can include a low-backlash gear unit, such as a type produced by Stober Drives, Inc. of Maysville, Ky., by way of a non-limiting example. The output gear can be coupled to an axle84that is coupled to the drive wheel62x. The axle84can have a plurality of splines configured to engage an output gear of the drive transmission80. In other embodiments, the output gear of the drive transmission80can be coupled directly to the drive wheel62x. The motor76and the drive transmission80are configured to cooperatively and swiftly drive the carriage60(and thus the robot4) along the track10with precise positional control along the axis12.

The drive assembly64includes a position encoder, such as a rotary encoder, which is preferably an absolute position rotary encoder, that is configured to transmit rotational position data to the carriage control module68. The rotary encoder can be coupled to the axle84or the drive wheel62xto provide direct rotary position data of the drive wheel62x. Alternatively, the rotary encoder can be coupled to one of the gears of the transmission80, such as the input gear or the output gear, for example. The carriage control module60can utilize the rotational position data from the rotary encoder as master location indicia. The carriage control module60can also compare the rotational position data from the rotary encoder to rotational position data from a rotary encoder of the motor for validation.

In the illustrated embodiment, the drive wheel62xis located at the first side60aof the carriage60and has a running surface63with a flat profile, as viewed in a sectional plane oriented orthogonal to the axis12, which flat profile is configured to roll along the primary surface30aof the first rail14a. Additionally, the drive wheel62xis paired with an upstop wheel62blocated below the drive wheel62xand having a flat profile configured to roll along the secondary surface30bof the first rail14a. The drive wheel62xand its paired upstop wheel62bare located at the first end60cof the carriage60in the illustrated embodiment, although they can be alternatively located at other locations along the carriage60.

Referring now toFIGS.5A and5B, as mentioned above, two pairs of wheels62, each such pair including a primary and upstop wheel62a,62b, can extend from the second side60bof the carriage60and are configured to travel along the second rail14b. The primary and upstop wheels62a,62bon the second side60bof the carriage60can each define a V-shaped profile complimentary with the V-shaped guide member36of the head30of the second rail14b. In particular, each primary wheel62aon the second side60bhas running surface63that defines a groove or channel37that defines angled support surfaces65a,65b, which provide these primary wheels62awith an inverted V-shaped profile, as viewed in a sectional plane oriented orthogonal to the axis12, which profile is complimentary with the inverted V-shaped profile of the primary surface30aof the second rail14b. Thus, the inverted V-shaped profiles of the primary wheels62aon the second side60bcan be characterized as “female” guide features, while the inverted V-shaped profile of the primary surface30aof the second rail14bcan be characterized as a complimentary “male” guide member36. Additionally, each upstop wheel62bon the second side60bhas beveled, chamfered, or otherwise canted support surfaces65c,65dthat provide these upstop wheels62bwith an apexed profile, such as an inverted V-shaped profile in the sectional plane, which profile is complimentary with the inverted V-shaped profile of the secondary surface30bof the second rail14b. The inverted V-shaped profiles of the upstop wheels62bon the second side60bcan be characterized as male guide features, while the inverted V-shaped profile of the secondary surface30bof the second rail14bcan be characterized as a complementary female guide member36. The guide member36and the complimentarily shaped primary wheels62aand upstop wheels62bon the second side60bof the carriage60are configured to maintain the relative position, with respect to the second direction Y, of the wheels62on the second side of the carriage60and the second rail14b, thereby guiding the carriage60as it travels along the rails14a,14b. Additionally, the angles at which the primary and secondary surfaces30a,30bof the second rail14and the associated support surfaces65a-dof the associated wheels62are oriented enhance the alignment of reactionary support forces imparted by the surfaces30a,30bof the second rail14bthat resist the bending moment forces imparted by the robot4to the second rail14bthrough the support surfaces65a-dof the wheels62on the second side60bof the carriage60.

It is to be appreciated that the particular configurations of the wheels62described above, including the respective shapes, locations, and pairings of the primary and secondary wheels62a,62bat both the first and second sides60a,60bof the carriage60(as well as the drive wheel62x), represent one example wheel configuration of the carriage60, while other wheel configurations are within the scope of the present disclosure. For example, the carriage60can include multiple drive wheels62x, which can be located on the same side60a,60bor at different sides60a,60bof the carriage60. Moreover, the primary wheels62aand upstop wheels62bneed not be located in pairs, and can be located or otherwise distributed along the carriage60as desired.

One or more and preferably all of the upstop wheels62b, including those on both the first and second sides60a,60bof the carriage60, can be biased or “pre-loaded” against the respective secondary surface30bof the first and second rails14a,14b. In this manner, the upstop wheels62bcan maintain engagement with the heads30of the rails14a,14b, enhancing the stability of the carriage60one the track10.FIG.5Cshows an example of such a biasing element that pre-loads the upstop wheel62bagainst the secondary surface30bof the respective rail14a,14b. As shown, the upstop wheel62bcan be coupled to the carriage60via an eccentric pin67that is torqued or otherwise rotated and affixed in a manner biasing the upstop wheel62bagainst the secondary surface30bof the associated rail14a,14b. Each of the upstop wheels62bcan be pre-loaded in this manner. It is to be appreciated that other means for biasing the upstop wheels62bagainst the secondary surfaces30bof the rails14a,14bare within the scope of the present disclosure.

Referring now toFIGS.5C and6, the carriage power assembly66includes a power collector90that has one or more electrical contacts91in translational or sliding electrical engagement with the power transmitter18. Thus, the engagement between the power transmitter18and the power collector90can be characterized as a stationary-to-mobile power coupling. The power collector90can be carried by a mounting feature, such as a bracket95, that positions the power collector90underneath the carriage60and adjacent the power transmitter18. The power collector90preferably includes a plurality of electrical contacts91a-d(also referred to as “current collectors”) each in sliding engagement with a respective one of the conductive strips41a-dof the bus bar40. The electrical contacts91a-dcan be carried by a plurality of collector arms92extending from a collector hub93. In particular, a first end92aof each collector arm92can be coupled to the hub93, while a second end92bof each collector arm92can be coupled to a contact mount94that carries the respective electrical contact91a-d. The collector arms92can position the electrical contacts91a-din sliding engagement with the associated conductive strips41a-d. For example, the collector arms92and mounts94can position the electrical contacts91a-dthrough the openings45and into the interior spaces44of the bus bar40so that the electrical contacts91a-dare maintained in sliding engagement with the conductive strips41a-d. The collector arms92and mounts94are preferably made of electrically insulative material. The mounts94can define tube ports or apertures96for receiving insulative tubing that houses wires providing electrical communication from each electrical contact91a-dto circuitry contained in a housing99of the carriage power assembly66. The circuitry is configured for, among other things, accumulating the electrical current collected by the electrical contacts91a-dand transmitting the electrical current to the motor76and/or the carriage control module68. It is to be appreciated that the mounts94can be spring-loaded to the collector arms92or otherwise configured to bias the sliding contacts91a-dinto engagement with the conductive strips41a-d.

Additionally, as shown, the power collector90can include a pair of collector arms92, each carrying an electrical contact91, for each of the conductive strips41a-d. The collector arms92of each pair can extend from opposite ends of the hub93with respect to the first direction X. In this manner, at least one of the collector arms92of each pair is towed during movement of the carriage60along the track10. In the illustrated embodiments, the power collector90includes four collector arms92extending from one end of the hub93and each carrying an electrical contact91a-dconfigured to engage a respective one of the conductive strips41a-d, as well as an additional four collector arms92extending from the other end of the hub93and each carrying an electrical contact91a-dconfigured to engage a respective one of the conductive strips41a-d. In this manner, the power collector90can be characterized as a “dual” power collector because two electrical contacts91are in sliding engagement with each of the conductive strips41a-d. It is to be appreciated, however, that a “single” power collector90configuration can be employed having a single collector arm92for each of the respective conductive strips41a-d. In such an embodiment for employment with the bus bar40shown, the power collector90would have a total of four collector arms92, each carrying an electrical contact91for sliding engagement with a respective one of the conductive strips41a-d. It is further to be appreciated that other configurations for the power collector90can be employed for providing sliding engagement between the carriage power assembly66and the power transmitter18.

It is also to be appreciated that other modes of powering the carriage60and the robot4can be employed that need not employ cables that physically tether the carriage60or robot4to a fixed location. By way of non-limiting examples, such other power modes can include inductive power transfer (IPT) and/or capacitive power transfer (CPT) between the track10and the carriage60, and/or one or more rechargeable batteries located on the carriage60.

As described above, the carriage60includes a transceiver72, such as a radio antenna, configured to receive and send data, such as via radio waves, from and to the radiating cable50. The carriage transceiver72is in electronic communication with the carriage control module68, whereby the processor70can interpret the data communicated through the radiating cable50, such as the robot control data and the carriage control data, and control movement of the robot4and the carriage60accordingly. The carriage transceiver72is preferably positioned on the carriage60at a location that is maintained in close proximity to the radiating cable50as the carriage60moves along the track10. The carriage transceiver72can optionally be in electronic communication with the carriage control module68via the circuitry in the housing99of the carriage power assembly66. It is to be appreciated that instead of a single carriage control module68that controls operation of the robot4and movement of the carriage60, the carriage60can employ separate control modules, such as a robot control module for controlling the robot4and a carriage control module for controlling movement of the carriage60along the track10.

Referring again toFIG.1A, example methods of operating the mobile robot system2will now be described. A plurality of items can be conveyed to a staging region adjacent the track10, such as the first staging region13a, for example. The system control unit100can cause the carriage60to move the robot4to a location along the track10alongside or otherwise adjacent the first staging region13a. As this location, the robot4can manipulate at least one of the items, such as by picking the at least one item. For example, the robot4can pick the at least one item and at the first staging region13aand deposit the at least one item at an adjacent staging region13n, which can be on the same side or the opposite side of the track10. Alternatively, the robot4can pick the at least one item at the first staging region13aand hold the at least one item for conveyance along the track10to another staging region, such as the second staging region13b, for example. Thus, it can be said that the robot4can manipulate at least one item at one staging region, move along the track10to a location adjacent an additional staging location, and manipulate the at least one item or at least one other item at the additional staging region.

The example method includes moving the carriage along the track, thereby conveying the robot along the track10to various locations along the track10as needed, which locations can be alongside or otherwise adjacent any of the various staging regions13a,13b,13n. For example, one or more of the staging regions13a,13b,13ncan be an incoming staging region, such as an output zone of a mechanical conveyor, for example, at which items are conveyed to the robot4. Additionally, one or more of the staging regions13a,13b,13ncan be an outgoing staging region, such as an induction zone of a mechanical conveyor, for example, at which items are conveyed away from the robot4to downstream processes within the fulfilment center. Accordingly, the robot4can optionally pick incoming items from one or more incoming staging regions, travel along the track (via movement of the carriage60) with the picked items to one or more outgoing staging regions, and deposit the items at the one or more outgoing staging regions, as controlled by the system control unit100. It is to be appreciated that the robotic work cell7described herein provides a vast number of options for sorting items with the mobile robot system2.

Each step of moving the carriage60along the track10can be completed utilizing the following sequence. The system control unit100can send a command signal to the communication control unit55, which command signal can include carriage control data, such as updated location data, for positioning the carriage60(and thus also the robot4) at a particular location along the axis12of the track10. The signal generator of the communication control unit55can convert the carriage control data into the data transmission mode employed by the transmission device20, such as radio waves, and transmits the radio waves through the radiating cable50. The carriage transceiver72receives the radio waves transmitting the carriage control data, and then transmits the carriage control data to the control module68. The processor70of the control module68interprets the carriage control data and sends drive command signals to the drive assembly64to drive the carriage60to the commanded location along the track10indicated in the carriage control data. The drive command signals can disengage the brake86of the drive wheel62xand energize the motor76to rotate the drive wheel62x, thereby driving the carriage60(and thus the robot4) to the commanded location. The drive command signals preferably also engage the brake86when the carriage60arrives at the command location, thereby temporarily affixing the location of the carriage60and robot4while the robot4manipulates one or more items from the command location. The foregoing sequence can be repeated for each update to the location data sent by the system control unit100.

Each step of moving the carriage60along the track10also includes supplying power to the motor76. In the embodiments illustrated herein, the supplying step includes sliding at least one electrical contact91carried by the carriage60along at least one conductive strip41of the power transmitter18of the track10. As described above, the at least one electrical contact91can be a plurality of electrical contacts91a-dof the power collector90, which electrical contacts91a-dslide along a respective plurality of conductive strips41a-dof the bus bar40.

It is to be appreciated that operation of the mobile robot system2is not limited to the example methods and steps set forth above.

It is also to be appreciated that a mobile robot system as described herein can employ multiple robot-carrying carriages60using the same track10. For example, the track10of a mobile robot system2can extend through multiple robot work cells7, each such work cell7having its own carriage-mounted robot4. In such embodiments, the system2can include a robot staging area along the track10. At the beginning of a work period, the carriage-mounted robots4can travel along the track10from the robot staging area to their designated work cells7. Such a system can also include one or more side tracks onto which the robots4can be diverted, such as when they may need maintenance or repair, without impeding travel of the other robots4on the track10.

It should be noted that the illustrations and descriptions of the embodiments shown in the figures are for exemplary purposes only, and should not be construed limiting the disclosure. One skilled in the art will appreciate that the present disclosure contemplates various embodiments. Additionally, it should be understood that the concepts described above with the above-described embodiments may be employed alone or in combination with any of the other embodiments described above. It should further be appreciated that the various alternative embodiments described above with respect to one illustrated embodiment can apply to all embodiments as described herein, unless otherwise indicated. Also, the present invention is not intended to be limited by any description of drawbacks or problems with any prior art device.