Material handling apparatus with vehicle track for reducing vehicle damage

A method and apparatus are provided for delivering items to a plurality of storage locations is provided. The system includes a plurality of storage locations. The storage locations may be positioned to provide an aisle and a plurality of delivery vehicles may be operable within the aisle to deliver items to the storage locations. The system may include a track that the guides the vehicles to the storage locations. A reorientation assembly may be provided for re-orienting the vehicles relative to the track to reduce misalignment between the vehicles and the track.

FIELD OF THE INVENTION

The present invention relates to material handling systems and, more particularly, to systems that utilize a plurality of storage locations in one or more storage racks. More particularly, the present invention relates to such material handling systems that utilize one or more automated delivery vehicles for delivering items to the storage locations

BACKGROUND OF THE INVENTION

The use of automated storage and retrieval has significantly improved the efficiency of material handling. For instance, in the order fulfillment application, automated storage and retrieval systems have significantly reduced the time required to retrieve the items required to fulfill a customer order. A variety of automated storage and retrieval systems are currently known. One exemplary type of system utilizes one or more storage racks, a plurality of vehicles and a track for guiding the vehicles to the storage locations on the racks. The vehicles deliver items to storage locations or bins where operators may remove the items from the storage locations to fulfill orders. Over time, the vehicles may tend to jam or become damaged from interaction with the track. Accordingly, it would be desirable to provide a system having a track that minimizes wear and damage to the vehicles that travel along the track.

SUMMARY OF THE INVENTION

According to one aspect, the present invention provides a material handling apparatus that includes a plurality of sort locations for receiving items. The system may include one or more vehicles for delivering items to the sort location. The vehicles may travel along a track. The track may include a section for improving interaction between the vehicles and the track. In one embodiment, the section includes a portion that reduces engagement between driving elements on the vehicle and the track.

Optionally, the vehicle includes a drive mechanism that engages the track and the track includes a section that allows portions of the drive mechanism to disengage portions of the track.

The track may optionally include a profile configured to positively engage the drive mechanism of the vehicles.

According to a preferred embodiment, the track optionally includes teeth or recesses that engage mating elements of the drive mechanism of the vehicles.

While the methods and apparatus are described herein by way of example for several embodiments and illustrative drawings, those skilled in the art will recognize that the inventive methods and apparatus for sorting items using a dynamically reconfigurable sorting array are not limited to the embodiments or drawings described. It should be understood that the drawings and detailed description thereto are not intended to limit embodiments to the particular form disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the methods and apparatus for sorting items using one or more dynamically reconfigurable sorting array defined by the appended claims. Any headings used herein are for organizational purposes only and are not meant to limit the scope of the description or the claims. As used herein, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include”, “including”, and “includes” mean including, but not limited to.

DETAILED DESCRIPTION OF THE INVENTION

Referring now toFIGS. 1-6generally and toFIGS. 1-2specifically, a material handling apparatus is designated10. The system10may take any number of forms that incorporate a plurality of storage locations. In the present instance, the system includes a pair of spaced apart storage racks30,32with an aisle35formed between the storage racks. A plurality of automated delivery vehicles200may operate within the aisle35. In particular, the delivery vehicles200may travel along a track100that is positioned in the aisle, as described further below. Additionally, as shown inFIGS. 7-16and described in greater detail below, the system10may include one or more mechanisms for improving the engagement between the track and the vehicles. For instance, the track may optionally include a section for re-orienting the vehicle relative to the track.

In an exemplary system illustrated inFIGS. 1-2, the material handling apparatus includes an optional station for feeding items into the system. This station is referred to as the induction station20. The induction station20may determine an identifying characteristic for the items to be fed into the system. The identifying characteristic can be any of a variety of characteristics, such as a product number or UPC code. The identifying characteristic can be determined manually, such as by an operator. However, in the present instance, the induction station includes a scanning station22that may include a plurality of scanners, such as optical scanners in the form of a bar code scanner, digital camera or otherwise. The induction station may include a conveyor for conveying the items past the scanner or the operator may manually scan the items before they are fed into the system.

The induction station20optionally includes a conveyor such as a conveyor belt or a plurality of rollers for serially conveying items to a loading station where the items are loaded onto vehicles200. A plurality of items may be loaded onto each vehicle. However, in the present instance, each item is loaded onto a separate vehicle and the vehicle then delivers the item to one of the storage locations.

Although the configuration of the induction station may vary, details of an exemplary induction station are provided in U.S. Pat. No. 10,494,192. The entire description of U.S. Pat. No. 10,494,192 is hereby incorporated herein by reference. Additionally, it should be noted that the induction station is not a necessary element and that aspects of the invention can be utilized in a system that does not include an induction station.

Referring again toFIGS. 1-4, the details of the storage assembly will be described in greater detail. The system includes a plurality of storage locations40for storing items so that the items may be retrieved. In one configuration, the items are delivered to the storage locations by a plurality of automated vehicles200. Additionally, the system may be configured so that the items can be retrieved from the storage locations by the automated vehicles. Alternatively, the storage locations may be used to accumulate items so that an operator or other automated retrieval device can retrieve the items from the storage location. For instance, a storage bin45may be located in each storage location40and the system may deliver items to the different storage bins to fulfill customer orders. Once the system has delivered all of the items to a particular storage bin that are required for an order, an operator removes the storage bin45from the storage location40and replaces the full storage bin with an empty storage bin.

The storage locations may be arranged in any of a variety of orientations. For instance, referring toFIGS. 1-2, the system includes two opposing racks, a front rack30and a rear rack32. The racks30,32are spaced apart from one another, forming an aisle35between the racks. Optionally, the racks30,32may be connected by a plurality of cross brackets that interconnect the racks. In particular, a plurality of top cross brackets may extend between the tops of the racks and a plurality of cross braces may extend between the bottoms of the racks thereby connecting the racks and maintain the racks spaced apart to provide the aisle35.

The track100may follow any of a variety of configurations depending upon the application. One exemplary embodiment is illustrated in theFIG. 3, which includes a closed loop having a plurality of columns. Similarly, the system may be configured as a series of rows connected by vertical tracks. Additionally, the system may be an open track rather than a closed loop. Therefore, it should be understood that the loop configuration illustrated in the figures is only one example and that the track may take any of a variety of forms.

Referring again toFIG. 3, the track100optionally includes a horizontal upper rail114and a horizontal lower rail116. A plurality of vertical legs112extend between the upper horizontal leg114and the lower horizontal leg116. During transport, the vehicles travel up a pair of vertical legs from the loading station to the upper rail114. The vehicle then travels along the upper rail114in the direction of travel identified by arrow T1until reaching the column having the appropriate bin or destination. The vehicle then travels downwardly along two front vertical posts and two parallel rear posts until reaching the appropriate bin or destination, and then discharges the item into the bin or destination area. The vehicle then continues down the vertical legs until reaching the lower horizontal leg116. The vehicle then follows the lower rail back toward the loading station.

Referring toFIGS. 2 & 5, the track100includes a front track105and a rear track110. The front and rear tracks105,110are parallel tracks that cooperate to guide the vehicles around the track. In the discussion of the track, the front and rear tracks105,110are similarly configured opposing tracks that support the forward and rearward wheels220of the vehicles. In particular, in the present embodiment the rear track110is mirror of the front track105. Accordingly, a description of a portion of either the front or rear track also applies to the opposing front or rear track, except as stated otherwise below.

The details of the track may be substantially similar to the track as described in U.S. Pat. No. 7,861,844. The entire disclosure of U.S. Pat. No. 7,861,844 is hereby incorporated herein by reference.

Referring toFIG. 4, the track100includes a drive surface120that positively engages the cars to enable the car to travel along the track. The drive surface120may be any of a variety of configurations that engage drive elements on the vehicles. In particular the drive surface may be configured to mate with or mesh with drive elements on the vehicles. One such example of a drive surface120is a series of teeth, forming a rack that engages the wheels of the cars as described further below. Similarly, the track may include a series of recesses or detents that cooperate with corresponding elements, such as a sprocket or other element that projects from the wheels. In this way, the term “positively engaging” refers to engagement between the drive surface120and drive elements of the vehicle200that impedes the drive elements from sliding along the track100.

Optionally, the track may also include a guide surface122in the form of a generally flat surface adjacent the drive surface120. For example, the drive surface120may extend approximately halfway across the track and the guide surface122may extend across the other half of the track. As shown inFIG. 4, the drive surface120may be formed on an inner wall of the track and the opposing outer wall may be a generally flat surface parallel to the guide surface122of the inner wall.

As described above, the track may include a plurality of vertical legs112extending between the horizontal upper and lower rails114,116. An intersection may be formed at each section of the track at which one of the vertical legs intersects one of the horizontal legs. For instance, each intersection may include a pivotable gate125having a smooth curved inner race and a flat outer race that has drive surfaces that correspond to the drive surfaces120of the track. The gate125may pivot between a first position and a second position. In the first position, the gate125may be closed so that the straight outer race of the gate is aligned with the straight outer branch of the intersection. In the second position, the gate125may be open so that the curved inner race of the gate is aligned with the curved branch of the intersection.

In the foregoing description, the system10is described as having a plurality of output bins45. However, it should be understood that the system may include a variety of types of destinations, not simply output bins. For instance, in certain applications it may be desirable to sort items to a storage area, such as an area on a storage shelf. Alternatively, the destination may be an output device that conveys items to other locations. Accordingly, one type of destination is a bin; a second type is a shelf or other location on which the item is to be stored; and a third type of destination is an output device that may be used to convey the item to a different location. The system may include one or more of each of these types or other types of destinations.

Delivery Vehicles

Referring toFIGS. 5-6, the details of one of the delivery vehicles200will be described in greater detail. Each delivery vehicle200may be a semi-autonomous vehicle having an onboard drive system, including an onboard power supply. Each vehicle optionally includes a mechanism for loading and unloading items for delivery. An exemplary vehicle is illustrated and described in U.S. Pat. No. 7,861,844, which is incorporated herein by reference.

As discussed further below in detail, the vehicle includes a mechanism for driving the vehicle along the track200. The drive mechanism may include any of a variety of elements. In the present instance, the drive mechanism includes a plurality of wheels220that engage the track100.

Additionally, the vehicle200optionally incorporates a mechanism for loading an item onto the vehicle and discharging the item from the vehicle into one of the bins. The loading/unloading mechanism210may be specifically tailored for a particular application. For example, the delivery vehicle200may include a platform onto which an item may be placed. The platform210may be a stationary platform and the system may include elements operable to load items onto the platform and unload items from the platform. Alternatively, the platform may be moveable. For instance, the platform may be one or more horizontal belts. The belts may be selectively operable to convey an item onto the vehicle. Similarly, the belts may be selectively operable to discharge items from the belt. In the present instance, the loading/unloading mechanism210is illustrated as one or more conveyor belts that extend along the top surface of the vehicle. The conveyor belts are reversible. Driving the belts in a first direction displaces the item toward the rearward end of the vehicle; driving the belt in a second direction displaces the item toward the forward end of the vehicle.

The vehicle may include a conveyor motor mounted on the underside of the vehicle to drive the conveyor belts. The conveyor belts may be entrained around a forward roller at the forward edge of the vehicle, and a rearward roller at the rearward edge of the vehicle. The conveyor motor may be connected with the forward roller to drive the forward roller, thereby operating the conveyor belts.

The vehicle200includes a plurality of wheels. As shown inFIGS. 5-6, each of the vehicles may include four wheels220: two forward wheels and two rearward wheels. The terms forward and rearward refer to the track in which the wheels ride as opposed to the direction of travel for the vehicle. Specifically, the forward wheels220a,220cride in the front track105, while the rearward wheels220b,220dride in the rear track110.

The wheels220are mounted onto two parallel spaced apart axles215,216so that two of the wheels are disposed along the forward edge of the vehicle and two of the wheels are disposed along the rearward edge of the vehicle. Specifically, wheels220aand220bare mounted on leading axle215, whereas wheels220cand220dare mounted on trailing axle216. Axle215is referred to as the leading axle because when moving in a horizontal direction, the vehicle typically moves in a direction in which axle215is leading and axle216is trailing. However, it should be understood that the vehicle may be reversed so that axle216becomes the leading axle and axle215becomes the trailing axle. Accordingly, it should be understood that the terms leading and trailing do not imply a requirement or limitation on the orientation of the vehicle and its direction of travel.

Each wheel220may comprise a drive element222that cooperates with a drive surface of the track. The drive elements may be any of a variety of elements configured to mate with the drive surfaces120of the track. For example, the drive elements may be rotatable elements such as cogwheels or sprockets. In the present instance, the drive elements222are gears, such as pinion gears having a plurality of teeth.

Each wheel optionally includes a guide element in addition to the drive element222. The guide element guides the wheel along areas of the track in which the track transitions from one direction to another direction. The guide element may also carry some of the load of the vehicle. According to one embodiment, the guide element may be a roller such as an idler roller224. The roller224may be coaxially with and positioned next to the drive element222. The idler roller224may engage the track to roll along the track while the drive element222engages the drive surface120to drive the vehicle along the track.

The drive element222may be fixed relative to the axle onto which it is mounted. In this way, rotating the axle operates to drive the drive element to drive the vehicle along the track100. Optionally, the roller224may rotate relative to the axle onto which it is mounted so that the rollers do not provide a driving force driving the vehicle forwardly.

Optionally, the drive elements of the vehicle are configured so that a first drive element on the first axle engages the front track and a second drive element of the first axle engages the rear track. Similarly, a first drive element on the second axle engages the front track and a second drive element on the second axle engages the rear track. In this way, two spaced apart drive elements, such as gears222aand222c, engage the front track105and two spaced apart drive elements, such as gears222band222d, engage the rear track110.

The vehicle includes an onboard motor for driving the wheels220. More specifically, the drive motor is operatively connected with the axles to rotate the axles215,216which in turn rotates the gears222of the wheels.

The vehicle200may be powered by an external power supply, such as a contact along the rail that provides the electric power needed to drive the vehicle. However, in the present instance, the vehicle includes an onboard power source that provides the requisite power for both the drive motor and the conveyor motor. Additionally, in the present instance, the power supply is rechargeable. Although the power supply may include a power source, such as a rechargeable battery, in the present instance, the power supply is made up of one or more ultracapacitors.

During operation, the engagement between the vehicle drive elements222and the track100provide precise control of the position of the vehicle200along the track. Additionally, since the rear track110is a mirror of the front track105, the opposing tracks controls the position of the forward wheels220a,220crelative to the rearward wheels220b,220d. Specifically, the drive surfaces on the front track105are aligned with the drive surfaces on the rear track110. For instance, if the drive surfaces120are teeth as shown inFIGS. 8 & 10, the first tooth120aalong the front track116aligns with the first tooth120balong the rear track. In this way, when the front drive element222aon the leading axle engages first tooth element120aof the front track105, the rear drive element222bon the leading axle215simultaneously engages first tooth element120bon the rear track110. Similarly, when the front drive element222con the trailing axle engages first tooth element120aof the front track105, the rear drive element222don the trailing axle215simultaneously engages first tooth element120bon the rear track110.

Because the drive surfaces of the track100tend to impede the drive elements222of the vehicle from sliding relative to the track, the positive engagement between the drive surfaces and the drive elements tends to maintain the vehicle in a proper orientation relative to the track. In particular, the aligned drive elements222and drive surfaces120tend to maintain the axles215,216parallel to one another and perpendicular to the direction of travel along the track. Although the vehicles positively engage the track in a manner to limit slippage between the vehicle and the track, the drive elements of the vehicle may become misaligned over time, causing stress on the vehicle, leading to vehicle wear and/or the vehicles becoming jammed within the track.

To limit wear, the system may incorporate a section for automatically reorienting the vehicle relative to the track. For instance, the system may include a section that facilitates aligning the drive elements of the vehicles with the drive surfaces of the track. The re-orientation section may have any of a variety of configurations, however, the section is designed to provide a section of limited slip in which engagement between the drive elements and the drive surfaces is reduced or discontinued.

Referring now toFIGS. 7-12, a section for automatically re-orienting the vehicle relative to the track is designated generally140. In the illustrated embodiment, the re-orientation assembly140is configured to reduce skew between the front side of the vehicle and the rearward side of the vehicle. For example, one of the front wheels (e.g. wheel220a) may be offset from the opposing rearward wheel (e.g. wheel220b) so that the two wheels are not positioned at the same point along the length of the track. Specifically, the distance from wheel220ato tooth120amay be greater than the distance from wheel220bto tooth120b. Such offset wheels may cause the axle215to bend or to become angled relative to the direction of travel T. For instance, as discussed above, in the illustrated embodiment, when the vehicle is properly oriented, the axles215,216are oriented perpendicular to the direction of travel. When the wheels220become offset the axles may bend or skew to an angle that is non-perpendicular to the direction of travel.

The re-orientation section140may include one or more segments depending on the configuration of the vehicles220. In one example, as illustrated inFIG. 8, the re-orientation section140includes a first segment150and a second segment spaced160apart from the first segment. Although the spacing between the first and second segments may vary, the first segment150is spaced apart from the second segment160a distance along the track similar to the spacing between the leading axle215and the trailing axle216. In this way, the wheels of the trailing axle216may engage the first segment150while the wheels of the leading axle215engage the second segment160(seeFIGS. 7-8).

Referring toFIGS. 7-12, the first segment150of the re-orientation section140includes a front assembly152and an opposing rear assembly154. The front assembly152is positioned along the front track105and the rear assembly154is positioned along the rear track110. As discussed further below, the front assembly152may be a mirror of the rear assembly154so that the front assembly and the rear assembly are substantially the same. Optionally, the front assembly152may be configured differently than the rear assembly154, as discussed further below.

Referring toFIGS. 7-8, the first segment150includes front assembly152and rear assembly154. The second segment160includes front assembly162and rear assembly164. The different segments are designated according to the direction of travel of the vehicle. For instance, as shown inFIG. 7, the typical direction of travel for the vehicle is designated by arrow T. When the vehicle travels in direction T, the leading edge of the vehicle is conveyed through the first segment150of the reorientation assembly140. As the vehicle continues along the path in the direction T, the leading edge is conveyed through the second segment160. However, it should be understood that the placement of the segments of the reorientation assembly140may vary depending upon a number of factors, including, but not limited to, the primary direction of travel of the vehicles along the track.

As noted above, the first and second segments150,160of reorientation assembly140each include a front assembly152,162along the front track105. Referring toFIGS. 11 and 12, details of the front assembly162of the second segment160will be described in greater detail. The front assembly includes a track section170. The track section170has a generally c-shaped channel cross-sectional profile. Specifically, a bottom wall180of the track forms a first wall of the channel and an opposing upper wall opposing the bottom wall forms a second wall. The upper and lower walls are connected be an elongated web that extends between the upper and lower walls.

The upper wall of the track segment170optionally includes a plurality of surfaces. For instance, the upper wall may include a generally flat guide surface171opposing the lower wall and extending substantially the entire length of the track segment170. The guide surface171may form a recess that extends the length of the upper wall. Additionally, the guide surface171may be spaced apart from the lower wall180a distance similar to the diameter of the guide wheels224of the vehicle wheels. The guide wheels have a generally smooth surface that provide rolling engagement between the guide wheels and the guide surfaces171,180.

The upper wall also includes a sliding surface173configured to facilitate sliding between the drive elements222of the vehicle and the track100. For instance, the sliding section173may be configured to provide a gap between the outer surface of the drive elements222and the drive surface120of the track. The sliding surface173is aligned with the drive surface120of the track100. In this way, the sliding surface forms a gap between a length of drive surface120on one portion of the track and a separate length of drive surface on a second portion spaced apart from the first portion.

For example, referring toFIG. 12, a first drive surface172may be formed on the upper wall at a first end of the track segment170. The first drive surface172is formed similarly to the drive surface120of the track100. For instance, the first drive surface172may be a plurality of spaced apart teeth that mesh with the gears222. Additionally, the track segment170may include a second drive surface174formed on the upper wall at a second end of the track segment170. The second drive surface is formed similarly to the drive surface120of the track, such as a plurality of spaced apart teeth like the first drive surface172. The second drive surface174is spaced apart from the first drive surface forming a gap between the two drive surfaces. The sliding surface173extends between the first drive surface172and the second drive surface174.

As mentioned above, the sliding surface173is configured to facilitate sliding between the track100and drive elements222of the vehicle wheels220. For instance, sliding surface173may be configured so that the sliding surface is spaced apart from the lower wall170a distance greater than the outer diameter of the drive elements222. For instance, sliding surface173may be a smooth planar wall so that the drive elements222of the vehicle wheels do not positively engage the sliding surface. In this way, the drive elements222may slide relative to the sliding surface173.

As described above, the sliding surface173of the track segment170allows a wheel of the vehicle to slide relative to the track. In this way, the sliding surface facilitates realignment of a wheel on one side of the track relative to the opposing wheel on the other side of the track. For instance, if front wheel222askips one or more teeth in the front track105, the front wheel222amay become skewed relative to the back wheel222bin the rear track110. More specifically, the wheel at one end of an axle215may become offset relative to the wheel at the second end of the axle. When one of the wheels is skewed or misaligned relative to a second wheel, the skew or misalignment may cause excessive wear and/or a jam between the vehicle and the track. As discussed further below, the sliding surface173allows the vehicle wheels to slide relative to the track to reorient the wheels to reduce skew and/or misalignment of the vehicle wheels.

The reorientation segment160provides an elongated segment in which the drive surfaces120of the track are modified or discontinued so that the drive elements222of the vehicle are disengaged from the drive elements. As shown inFIG. 11, the reorientation assembly may include one or more transition section to transition the drive elements of the vehicle from engaging with the drive surfaces to non-engaging and from non-engaging to engaging with the drive surfaces. For example, drive surface172is configured to have a first end that substantially matches the configuration of the drive surfaces120of the track. The second end of the drive surface tapers from the configuration of a full drive surface to a reduced drive surface and/or to no drive surface. For example, in the illustrated embodiment, the drive surfaces are teeth, such as a rack and the drive surface172tapers from a full-sized tooth to a reduced height tooth to no tooth. In this way the meshing between the gear teeth222on the vehicle200and the drive surface172progressively disengages. Similarly, the drive surface174tapers in the reverse direction to progressively mesh with the gear teeth222of the vehicle. Specifically, the second drive surface174tapers from either no teeth or a reduced tooth height to a full tooth height that matches the configuration of the drive surfaces120of the track100.

Although the transition sections172,174are illustrated as being integral with the track section170, it should be understood that the transition sections172,174may be formed on adjacent sections of the track100so that the sliding surface173extends further along the track segment170.

Optionally, the reorientation assembly140may further include a secondary reorienting device. For instance, the reorientation assembly may include a centering element for limiting skew of the vehicle relative to the desired direction of travel. An example of such a centering device is illustrated inFIGS. 11-12in the form of a deflector195configured to deflect the vehicle toward the desired direction of travel. The deflector195may be any of a variety of elements designed to apply lateral force on the side of the vehicle.

In the present instance, the deflector195includes one or more biasing elements that urge the vehicle toward the centerline between the front and rearward tracks105,110. Specifically, the deflector includes a pivotable lever that pivots about a pivot pin198. The pivot pin198extends through a bore hole196in the deflector195. In this way, the pivot pin198forms a pivot axis so that the deflector pivots about an axis that is preferably transverse to the direction of travel T (SeeFIGS. 7-10).

The deflector195projects through an aperture or window165in the web of the track segment160. In the present instance, a biasing element, such as a spring197biases the deflector165toward the center of the aisle35. In other words, the deflector165is biased to urge against the side of the vehicle200. In this way, as the vehicle passes through the reorientation section, the deflector195may reorient the vehicle toward the center of the aisle. Additionally, referring toFIGS. 8 & 10, an opposing deflector195may be positioned in the rearward track110so that the opposing deflector urges against the opposite side of the vehicle200. In this way the two opposing deflectors urge the two sides of the vehicle toward the center of the aisle. For instance, as shown inFIG. 8, the deflector195in the front assembly162urges against the front side of the vehicle and the deflector195in the rear assembly164urges against the rearward side of the vehicle. Preferably, the opposing deflectors are balanced so that they provide substantially similar biasing forces, thereby urging the vehicle toward the center of the aisle to guide or reorient the center of the vehicle toward the center of the aisle.

As noted above, the reorientation segment162may include a housing190that houses the track segment170and the deflector195. For instance, the housing may be a C-shaped channel having a width and depth large enough that the track segment can fit within the housing. As shown inFIG. 12, the track segment170may have an upper and lower lip that fit over the outer edges191of the housing190. The track segment may be fixedly affixed to the housing, such as by releasable fastener (e.g. threaded fasteners) or by permanent means, such as welding, epoxy or adhesive.

The housing is optionally deep enough to provide clearance for the deflector195. Specifically, all, or substantially all of the deflector195may fit within the housing below the track so that the deflector does not substantially protrude into the track. In this way, the deflector195may be deflected or retracted into the housing190out of the path of the vehicle.

The pivot axis of the deflector195is optionally positioned below the surface of the web that connects the upper and lower legs of the track segment. For instance, in the present instance, the pivot axis196is positioned in a gap between the track segment170and the housing190. In particular, the pivot pin198is positioned below the track segment so that pivot pin does not extend through the track segment.

Optionally, the deflector195includes a biasing element197biasing the deflector inwardly toward the center of the aisle35.FIG. 12illustrates an exemplary biasing element in the form of a coil spring. The deflector may be configured to cooperate with the coil spring, such as a post that extends into the coil spring or a recess that receives a first end of the coil spring. The second end of the spring may bear against the interior wall of the housing. Alternatively, an aperture may be formed in the wall of the housing and a cover199may overlie the aperture in the housing. The biasing element197may bear against the interior surface of the cover. The cover197may be releasably or substantially permanently connected with the housing190.

The reorientation assembly140may include one or more reorientation segments152as described above. For instance, as illustrated inFIGS. 8 and 10, the second reorientation section160may include a front reorientation segment162along the front track105and a rear reorientation segment164opposing the front orientation segment162. The rear reorientation segment164may be configured substantially similarly to front reorientation segment160with the rear reorientation segment being substantially a mirror of the front reorientation segment.

The reorientation segment may include one or more reorientation elements. For instance, front reorientation assembly162of the second segment160includes both the sliding surface173and the deflector195. Referring toFIGS. 8 and 10, the first reorientation segment150may similarly have both a sliding surface for reorienting the vehicle and a secondary reorientation element, such as the deflector. Alternatively, the first reorientation segment150may include a track segment configured similarly to track segment170, but the first segment150may omit the deflector195.

Referring again toFIGS. 8 and 10, the first reorientation segment150may include a front section152that includes a sliding surface173and a rear section154that includes a track section having driving surfaces opposing the sliding surface173. Specifically, rear assembly154of the first reorientation segment150includes a track having drive surfaces120along substantially the entire length of the assembly. The drive surfaces120provide a positive drive mechanism through the entire length of the first segment.

In this way, the reorientation assembly may be configured in a number of variations that permit various elements of the vehicles to slide relative to the track at different areas of the reorientation assembly. As described above, the first reorientation segment150has a first sliding surface on one side and drive surfaces on the opposing portion of the track so that the front wheel of the vehicle may slide relative to the track while the rear wheel remains engaged with the track.

Additionally, the second reorientation segment160has a first sliding surface on one side and a second sliding surface on the opposing side so that both the front and rear wheels may slide relative to the track at the same time.

Optionally, the second reorientation segment160is spaced apart from the first reorientation segment150a distance similar to the distance between the leading axle215and the trailing axle216. In this way, the reorientation assembly140may allow three of the four corners of the vehicle to slide relative to the track100while the fourth corner of the vehicle remains engaged with the track. For instance, as described above, when the leading wheels220a,bengage the second reorientation segment160, the drive elements222a,222bare aligned with the sliding surfaces173so that the drive elements222a,222bare disengaged from the track. While the leading wheels engage the second reorientation segment, the trailing wheels220c,dengage the first reorientation segment150so that front drive element222cis aligned with the sliding surface of the front segment while the rear drive element222dis aligned with the drive surfaces. In this way, the drive element of a single wheel of the vehicle engages the drive surfaces of the track to drive the vehicle through the reorientation section while the remaining wheels222a,222b,222care disengaged from the drive surfaces of the track100.

It should be understood that the configuration of the reorientation assembly140may be varied depending on a variety of factors. For instance, as noted above, it may be desirable to incorporate a supplemental or secondary reorientation element such as deflector195into one or more of the reorientation segments. However, the reorientation assembly140may be configured without such secondary reorientation elements. Similarly, in the foregoing example, the reorientation assembly includes three segments that allow three wheels of the vehicle to simultaneously disengage from the drive surfaces of the track.

It may be desirable to reduce the number of segments that allow the wheels to disengage from the drive surfaces of the track. For instance, the reorientation assembly may include two segments that allow the wheels to simultaneously disengage the drive surfaces of the track. In one example, the two segments may oppose one another so that the two wheels that simultaneously disengage are on the same axle. Alternatively, the two segments may be spaced apart along the length of the track so that the two wheels that simultaneously disengage are spaced apart along the length of the vehicle. For instance, the two segments may be spaced apart a distance similar to the spacing between the leading axle215and the trailing axle216.

Referring now toFIGS. 13-16, an alternate embodiment of the skew correction assembly or reorientation assembly440for use in the material handling apparatus10is illustrated. The alternate reorientation assembly440is similar to the reorientation assembly140illustrated inFIGS. 7-12. However, as described below, the alternate reorientation assembly440may include an alterative secondary reorientation element485. As described above, the reorientation assembly140inFIGS. 7-12may include an optional deflector195that operates as a secondary reorientation element by deflecting the vehicle in an attempt to center the vehicle between the front track105and the rear track110. The alternate reorientation assembly440comprises a plurality of track elements that are substantially similar to the system illustrated inFIGS. 7-12. However, the system inFIGS. 13-16includes a stationary element that provides a secondary reorientation element485rather than the movable deflector195.

As shown inFIGS. 13-16the alternate reorientation assembly440allows three wheels of the vehicle to simultaneously slide along the track. For instance, the first reorientation segment450may include a front assembly452and a rear assembly456. The front assembly452may include a drive surface455similar to the drive surface120of rear assembly154inFIGS. 7-12. In contrast, the rear assembly494may include a sliding surface466similar to assembly164inFIGS. 7-12. Similarly, the second reorientation segment460may include opposing front and rear assemblies462,464configured substantially similar to rear assembly164so that the assembly has a sliding surface466.

More specifically, the three assemblies,456,462and464may be configured substantially similar to one another. Each assembly may include a sliding section466formed in the track similar to sliding surface173so that the vehicle wheel can slide along the sliding section. Additionally, similar to the assembly shown inFIG. 12, assemblies456,462,464may each include transition areas similar to transition elements172and174in which the track segment transitions from a drive element to the sliding surface or from the sliding surface to the drive elements.

The alternate secondary reorientation element485includes an elongated guide or fence. The fence485includes a generally vertical wall extending along the inner edge of the track. InFIGS. 13-14the fence is illustrated as being attached along the inner edge of the front track105, however, it should be understood that the fence may be positioned along the rear track instead.

FIG. 16illustrates a sectional view of the front assembly460. The fence485projects upwardly from the inner edge of the track forming a lateral stop impeding lateral displacement of the wheel relative to the track. In this instance, lateral displacement is horizontal displacement that is transverse the direction of travel.

The fence is positioned so that the fence is spaced apart from the inner surface of the track a distance similar to the thickness of the wheel220. For instance, the distance from the inner surface of the fence485to the inner surface of the track is less than approximately 120% of the width of the wheel220. Preferably, the distance from the inner surface of the fence485to the inner surface of the track is less than approximately 110% of the width of the wheel220. In this way, the fence and the inner surface of the track form guides that constrain lateral movement of the wheel transverse the direction of travel T. Similarly, the fence and the inner surface of the track form guides that constrain the ability of the wheel to twist or skew about a vertical axis.

The fence may be formed as a generally L-shaped structure having a lower leg487forming a bracket for attaching the fence to the track. In this way, the lower leg487may be fixedly connected with a lower surface of the housing490of the track.

Referring toFIG. 14, the fence485extends along the length of the reorientation assembly440. The fence485may be a single element or a plurality of elements may be positioned along the length of the reorientation assembly440. For instance, as shown inFIGS. 13-15, the fence may be a single guide extending along both the first reorientation segment450and the second reorientation segment460. However, the fence may be separate guides, such as a first fence positioned along the first reorientation segment450and a second fence that is spaced apart from the first fence and positioned along the second reorientation segment460. Either way, preferably the fence is elongated having a length at least as long as the shorter of the first and second reorientation segments450,460. Further still, the fence may have a length that is at least as long as the length of both the first reorientation segment and the second reorientation segment combined. Accordingly, the fence485is sufficiently long to impede lateral displacement of the vehicle200while three of the four wheels are disengaged from the drive surface120of the track100.

Method of Use

The system10provides an apparatus for automatically delivering and/or sorting a plurality of items using a plurality of vehicles200. Items may be scanned at an input station20and loaded onto the vehicles at a loading station adjacent the input station. From the loading station, the vehicles travel vertically and horizontally along a track to one of a variety of destination areas, such as one or a plurality of sort bins40. At the appropriate sort bin40, a vehicle200may transfer an item into the sort bin. After delivering the item, the vehicle continues along the track to return to the loading station to receive another item. The vehicle may continue to loop around the track picking up items at the loading station and delivering items to the sort bins.

As the vehicles move along the track, the vehicles positively engage the track. In particular, the track comprises a plurality of drive surfaces and the vehicles comprise a plurality of drive elements that mate with the drive surfaces of the track. The mating drive elements and drive surfaces impede the vehicle wheels from sliding along the track relative to the drive surfaces.

As the vehicles travel along the track, the vehicles may be reoriented relative to the track as the vehicles move along the track. In other words, the vehicles are reoriented while the vehicles move. The vehicles may be reoriented to correct a variety of potential misalignments between the vehicles and the track that can lead to excess wear or jamming. For instance, the vehicles may be reoriented to reduce or eliminate skew between wheels on opposing sides of the track. For example, the drive elements of a wheel on a first side of the vehicle may disengage the drive surface on the track while the drive element on a second side of the vehicle remains engaged with the drive surfaces on the track. When the drive elements of the wheel on the first side disengage the drive surfaces of the track, the wheel on the first side is free to move relative to the track, thereby reducing misalignment of the wheel on the first side relative to the wheel on the second side.

Additionally, the vehicles may be reoriented by simultaneously disengaging the drive elements of multiple wheels from the drive surfaces of multiple segments of the track. In this way, the drive elements of multiple wheels are free to move relative to the track while the drive elements of at least one wheel remain positively engaged with the track to drive the vehicle forward.

For example, the vehicles200may pass through a reorientation section140as the vehicles travel along the track100. The leading wheels220a,220bmay pass through a first segment150of the reorientation section while the trailing wheels220c,220dengage the teeth120in the forward and rear tracks105,110. As the leading wheels220a,220bpass through the first segment150, drive elements, such as gear222aof the first wheel220a, are displaced along the sliding surface173of track170. As the gear222ais displaced along the sliding surface173, the gear222ais disengaged from positive engagement with the track. If the front wheel220ais skewed relative to the rear wheel220b, the front wheel will tend to reorient into alignment with the rear wheel when the gear222aof the front wheel is disengaged from the track along the sliding surface173. If the front wheel220ais aligned with the rear wheel220b, the leading axle215will tend to be oriented in a desired orientation, such as normal to the direction of travel T. If the front wheel is misaligned from the rear wheel on the leading axle215, the leading axle may deflect or skew relative to the desired orientation. As the leading edge of the vehicle passes through the first orientation section, the deflection or skew of the leading axle may displace the front wheel220arelative to the rear wheel220bwhen the front wheel is released while the rear wheel remains engaged.

After passing through the first reorientation segment150, the leading wheels220a,220breengages the drive surfaces120of the track so that the leading wheels positively engage the track. The vehicle continues to move forwardly so that the leading wheels move through the second reorientation segment160. As the leading wheels move through the second reorientation segment160, the rear wheels move through the first reorientation segment150. In the present embodiment, the first and second reorientation segments are configured so that three of the four drive wheels220disengage the drive surfaces of the track while a single wheel remains engaged with the drive surfaces to drive the vehicle forwardly. In this way, three of the four wheels of the vehicle are released to correct skew or misalignment between one or more wheels on the first side of the vehicle and one or more wheels on the second side of the vehicle while also correcting skew or misalignment of one or more of the leading wheels relative to one or more of the trailing wheels.

After the trailing wheels220c,220dpass through the first reorientation segment150, the vehicle continues forward so that the trailing wheels enter the second reorientation segment150. In the second reorientation segment both trailing wheels220c,220ddisengage from the driving surface allowing both wheels to slide or translate relative to the track. When the trailing wheels220c,220ddisengage from the drive surface of the track, the leading wheels220a,220bpositively engage the track to drive the vehicle along the track.

The method may also include the step of impeding twisting and/or lateral displacement of the vehicle as the vehicle passes through the reorientation assembly. Specifically, according to one embodiment, the method may include the step of simultaneously applying a force to the side of the vehicle as the vehicle passes through the reorientation assembly. In particular, forces of similar magnitude and opposite direction may be applied to the two sides of the vehicle, urging the vehicle toward the center of the aisle. For instance, as described above, the second reorientation segment160may include deflectors195, a first deflector positioned along the front track105and the second deflector positioned along the rear track. The first deflector provides a force against the side of the vehicle in a direction toward the rear track. Similarly, the second deflector195provides a force against the opposite side of the vehicle in a direction toward the front track. The forces of the deflectors195may be provided by biasing elements so that the deflectors provide generally equal and opposite forces transverse the direction of travel T.

Alternatively, rather than a displaceable element for applying lateral forces to the vehicle, the reorientation assembly may include a fixed guide or stop that limits lateral displacement and/or twisting of the vehicle. Specifically, as noted above, the method may include releasing a plurality of vehicle wheels from engagement with drive surfaces to allow the plurality of wheels to slide relative to the track while one or more wheels remain engaged with a drive surface. The method may include the step of constraining lateral displacement of the vehicle while the plurality of wheels are disengaged from the drive surface. In one embodiment, the method includes the step of releasing three wheels from drive surfaces simultaneously while maintaining a wheel in engagement with a drive surface. While the three wheels are disengaged from the drive surfaces, the method includes the step of engaging one or more of the three released wheels with a stop to impede lateral displacement of the released wheels.

The method may also include the step of re-engaging one or more of the three released wheels with drive surfaces. Additionally, the method may include the step of releasing the one or more wheels from the stop after the step of re-engaging.

In view of the foregoing, the present invention may provide a system in which a plurality of vehicles move a long a track to deliver items to a plurality of locations. Optionally, the track may include a loop and the vehicles may circulate around the loop. The track may include a reorientation assembly that reorients the vehicles relative to drive surfaces on the track. The method may include the step of repeatedly engaging and disengaging the drive surfaces of select wheels of the vehicle while repeatedly engaging and disengaging one or more select wheels of the vehicle. The track is configured to allow the wheels to slide relative to the track when the wheels are disengaged from the drive surfaces. In this way, the drive elements on the wheels are displaced relative to the drive surfaces of the track to align the drive elements with the drive surfaces.

In the foregoing description, the reorientation assembly140,440is described as having two separate segments150,160and450,460. However, it should be understood that the number of segments in the reorientation assembly may vary. For example, the reorientation assembly140may include just a single reorientation segment150. In such an embodiment, the leading wheels220a,220bare reoriented when they pass through reorientation segment150and the trailing wheels220cand220dwill similarly be reoriented when they pass through the reorientation segment. In such an embodiment, the front assembly152and rear assembly154of the reorientation segment150may both include sliding surfaces. Accordingly, when the leading wheels220move through the reorientation segment both wheels disengage the drive surfaces of the track while the trailing wheels220c,220dremain engaged with the drive surfaces of the track to drive the vehicle forwardly. After moving through the reorientation segment150, the leading wheels220a,220bre-engage the drive surfaces of the track to drive the vehicle forward while the trailing wheels220c,220dmove through the reorientation segment and disengage the drive surfaces of the track.

As described above, the number of reorientation segments and the position of such segments may vary depending on numerous variables, including but not limited to the configuration of the vehicles, the number of wheels on the vehicles, the configuration of the drive surfaces of the track, and the configuration of the drive elements on the vehicles. Accordingly, it should be understood that the reorientation assembly140,440is not limited to the particular number of reorientation segments and/or the configuration of the reorientation segments described above.

Similarly, in the above description the reorientation assembly140,440may include a secondary reorientation element, such as deflectors195or fence485. The secondary reorientation element195,485may form part of the second reorientation segment160,460whereas the first reorientation segment150,450may not include deflectors195or guide485. Accordingly, it should be understood that the number and position of the secondary reorientation element may be varied based on a number of variables. Additionally, it should be understood that the reorientation assembly140,440may be configured without any secondary reorientation elements, such as the deflectors195or fence485.