Climbing robot with one way pinion drive

Abstract

A mobile robot configured to travel in a vertical or inclined passage comprising a rack including teeth is disclosed. The mobile robot includes a hub for mounting a wheel, a shaft engaged to the hub for rotation about an axis of rotation by a motor. The shaft is extendable axially along the axis of rotation from a retracted position to an extended position. The mobile robot includes a pinion mounted on an end of the shaft. The pinion includes teeth for meshing with the teeth of the rack upon extension of the shaft into the extended position. The mobile robot includes a one-way bearing coupled to the shaft and pinion such that the pinion interfaces with the shaft via the one-way bearing. The one-way bearing permits the pinion to rotate relative to the shaft in a first direction and prevents rotation of the pinion in a second, opposite, direction.

Description

CLIMBING ROBOT WITH ONE WAY PINION DRIVECROSS-REFERENCE TO RELATED APPLICATIONS)

[0001] This application claims priority to U.S. Provisional Application No. 63 / 609,694, filed on December 13, 2023, the disclosure of which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure relates generally to mobile robot travel that can move vertically, and more particularly to a pinion drive on a mobile robot that can engage a gear rack for vertical movement.BACKGROUND

[0003] Automated order fulfillment systems for use in supply chains fulfill orders for individual products. Traditional order fulfillment facilities store products in containers in a multi-level storage structure with a vertical and horizontal array of storage spaces. The automated order fulfillment systems may include mobile robots that move around the storage structure to transfer productcontaining containers or totes to and from the storage spaces within the structure. In one example, the storage structure may include horizontal floors or platforms around at least a portion of the storage structure enabling the mobile robots to travel to and from the storage structure, horizontal tracks enabling the mobile robots to travel horizontally to and from storage spaces on a given level, and vertical towers enabling mobile robots to travel vertically between levels.

[0004] It is known to provide pinion gears on opposed sides of the mobile robots, which mesh with toothed racks in opposed sides of the vertical towers to enable vertical travel. In operation, a mobile robot may approach a vertical tower from a horizontal floor, platform or rail. Once positioned in the vertical tower, motors in the mobile robot extend the pinion gears on opposed sides of the mobile robot along their common axis of rotation until the pinion gears engage within the racks. Rotation of the pinion gears may thereafter raise or lower the robot in the vertical tower. With this method of engagement, it may happen that a pinion gear does not mesh properly with the teeth of a rack as the pinion gear advances toward and into the rack, possibly even jamming against a side of the rail to prevent meshed engagement.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Disclosed herein are embodiments of autonomous mobile robot systems. This description includes drawings, wherein:

[0006] FIG. 1 is a side view of a climbing robot system in accordance with some embodiments;

[0007] FIG. 2 is a perspective view of a pinion in accordance with some embodiments;

[0008] FIG. 3A is a perspective view of a rack structure in accordance with some embodiments;

[0009] FIG. 3B is a side view of a pinion and a rack when the teeth of the pinion are meshed with the teeth of the rack in accordance with some embodiments;

[0010] FIG. 4 is a partial section view of a climbing robot in accordance with some embodiments;

[0011] FIG. 5 is a perspective view of a shaft and a pinion mounted on the rack in accordance with some embodiments;

[0012] FIG. 6 is a partial sectional view of the shaft and pinion of FIG. 5;

[0013] FIG. 7 is a side elevational view of the shaft and pinion of FIG. 5;

[0014] FIG. 8 is a partial sectional view of the shaft and pinion of FIG. 7;

[0015] FIG. 9 is a perspective exploded view of the shaft and pinion of FIG. 5;

[0016] FIG. 10 is a side exploded view of the shaft and pinion of FIG. 5;

[0017] FIG. 11 shows a perspective view of a shaft and pinion of a climbing robot relative to apportion of a rack structure when the shaft and pinion are in a retracted orientation in accordance with some embodiments;

[0018] FIG. 12 is a side elevational view of the shaft, pinion, and portion of the rack structure of FIG. 11;

[0019] FIG. 13 is a partial section view of the climbing robot and the racks of the rack structure, showing the shaft in a partially extended position in accordance with some embodiments;

[0020] FIG. 14 is a perspective view of the pinion on a shaft just beginning to engage the rack in accordance with some embodiments;

[0021] FIG. 15 is a side elevational view of the shaft, pinion, and rack of FIG. 14;

[0022] FIG. 16 is perspective view of the pinion engaging the rack after the teeth of the pinion initially intermesh with the teeth of the rack and the shaft is moved toward the fully extended position in accordance with some embodiments;

[0023] FIG. 17 is a side elevational view of the shaft, pinion, and rack of FIG. 16;

[0024] FIG. 18 shows a partial section view of the climbing robot showing one side of the climbing robot and one set of the racks, with the teeth of the pinion fully engaging the teeth of the rack while the shaft is in the fully extended position in accordance with some embodiments;

[0025] FIG. 19 shows a perspective view of the pinion fully engaged to the rack while the shaft is in the fully extended position in accordance with some embodiments; and

[0026] FIG. 20 shows a side elevational view of this position of the shaft and pinion relative to the rack in accordance with some embodiments.DETAILED DESCRIPTION

[0027] Generally speaking, pursuant to various embodiments, systems, apparatuses and methods are provided herein useful to assist a mobile robot in vertical movement through a system.

[0028] In some embodiments, a mobile robot configured to travel in a vertical or inclined passage comprising a rack including teeth includes: a hub for mounting a wheel; a shaft engaged to the hub and configured to be rotated about an axis of rotation by a motor, the shaft further configured to be extended axially along the axis of rotation from a retracted position to an extended position; a pinion mounted on an end of the shaft, the pinion including teeth configured to mesh with the teeth of the rack and to move into engagement with the rack upon extension of the shaft into the extended position; and a one-way bearing coupled to the shaft and to the pinion such that the pinioninterfaces with the shaft via the one way bearing. The one-way bearing is configured to: permit the pinion to rotate relative to the shaft in a first direction to prevent jamming of the teeth of the pinion against the teeth of the rack when the pinion moves into engagement with the rack upon extension of the shaft into the extended position; and prevent rotation of the pinion in a second direction opposite to the first direction.

[0029] In some embodiments, an order fulfilment system includes: a multilevel storage structure having storage locations in different levels, and a vertical or inclined passage extending between the different levels, the passage comprising a rack including teeth; and a mobile robot configured to travel between the levels in the passage. The mobile robot includes: a hub for mounting a wheel; a shaft engaged to the hub and configured to be rotated about an axis of rotation by a motor, the shaft further configured to be extended axially along the axis of rotation from a retracted position to an extended position; a pinion mounted on an end of the shaft, the pinion including teeth configured to mesh with the teeth of the rack and to move into engagement with the rack upon extension of the shaft into the extended position; and a one-way bearing coupled to the shaft and to the pinion such that the pinion interfaces with the shaft via the one way bearing. The oneway bearing is configured to: permit the pinion to rotate relative to the shaft in a first direction to prevent jamming of the teeth of the pinion against the teeth of the rack when the pinion moves into engagement with the rack upon extension of the shaft into the extended position; and prevent rotation of the pinion in a second direction opposite to the first direction.

[0030] In some embodiments, a method of transporting a mobile robot along a vertical or inclined passage comprising a rack including teeth includes: extending a pinion including teeth of the mobile robot from a first position spaced from the rack to a second position where the teeth of the pinion engage with the teeth of the rack, wherein the pinion is mounted to a shaft configured to be rotated about an axis of rotation by a motor and to be extended axially along the axis of rotation from a retracted position to an extended position; rotating, after extension of the shaft into the extended position, the shaft and pinion by a motor, the shaft rotating by a force exerted by the motor on the shaft; and preventing jamming of the teeth of the pinion against the teeth of the rack when the pinion moves into the second position to engage the teeth of the rack upon extension of the shaft into the extended position by providing a one-way bearing coupled to the shaft and to the pinion such that the pinion interfaces with the shaft via the one way bearing. The one-way bearingis configured to: permit the pinion to rotate relative to the shaft in a first direction; and prevent rotation of the pinion in a second direction opposite to the first direction.

[0031] FIG. 1 shows a side view of an exemplary embodiment of an autonomous robotic vehicle 10 (also referred to herein as a “climbing robot”). Generally, the climbing robot 10 may be configured for use within an order fulfillment system and may have features as described in U.S. Patent No. 11,142,398 and U.S. Publication No. 2020 / 0087067 Al, each of which is incorporated by reference herein in its entirety.

[0032] In some embodiments, an exemplary order fulfillment system may have a multilevel tote storage and retrieval structure, autonomous robotic vehicles 10 configured to pick, transport and place one or more totes within the order fulfillment system, workstations configured to accommodate a picker (human, automated or otherwise) that transports one or more eaches from a tote, for example a product tote containing multiple common eaches to be picked, on one of the autonomous mobile robots to a desired location, for example an order tote that has a combination of different eaches that reflects a full or partially fulfilled order, that may be on another of the autonomous mobile robots at the workstation, transit decks configured to support, stage and buffer the climbing robots 10 between the storage and retrieval structure and the workstations, a dispense station where totes containing fulfilled orders are discharged from the order fulfillment apparatus and a decant or input interface (not shown) configured to replenish the apparatus.

[0033] The exemplary climbing robot 10 illustrated in FIG. 1 has drive wheels 12, support wheels 14, guide rollers 16, pinion 18, counterwheel 19 and counterwheel 20. As will be described in greater detail below, the pinion 18, counterwheel 19, and counterwheel 20 selectively engage a rack 82 allowing the climbing robot 10 to climb or descend vertically. While climbing, the counterwheels 19 and 20 react to the cantilevered weight of climbing robot 10 such that force 24 reacts with the counterwheel 20, force 26 reacts with the counterwheel 19, the pinion 18 vertically supports the weight 28 of robot 10, and the counterwheels 19, 20 react the moment.

[0034] FIG. 2 shows a perspective view of an exemplary pinion 18, which may be also referred to herein as a drive gear, and which has teeth 40 positioned along an exterior circumference thereof. In the embodiment illustrated in FIG. 2, the pinion 18 includes 18 teeth 40, but it will be appreciated that the pinion 18 may have any suitable number of teeth 40 depending on the circumference of the pinion 18. In some embodiments, the teeth 40 of the pinion 18 may have achamfered lead in portion 44 (see., e ., FIGS. 3 and 5) that is provided to facilitate a proper meshing engagement of the teeth 40 of the pinion with the teeth 94 of the rack 82 without jamming upon axial extension of the shaft 122. In some aspects, the lead in portion 44 of each of the teeth 40 may have a double chamfer. As shown, for example, in FIG. 3A, each of the teeth 94 of the rack 82 may include a chamfered lead in portion 95 (which also may be double-chamfered in some embodiments) complementary to the chamfered lead in portion 44 of each of the teeth 40 of the pinion 18 and configured to facilitate the meshing engagement of the teeth 40 of the pinion 18 with the teeth 94 of the rack 82 without jamming upon the axial extension of the shaft 122.

[0035] FIG. 3A shows a view of a portion of an exemplary rack structure 80. In the illustrated embodiment, the rack structure 80 has a rack 82 (also referred to herein as a linear drive mount), counterwheel support surfaces 84, 86 (which support the counterwheel 19 in some embodiments, as discussed in more detail below), robot support rails 88, 90 and a frame 92. As pointed out above and shown in FIG. 3A, some the teeth 94 of the rack 82 may have a chamfered (single-chamfered or double chamfered) lead in portion 95 that is provided to facilitate proper intermeshing of the teeth 40 of the pinion 18 with the teeth 94 of the rack 82 and to prevent j amming when the teeth 40 of the pinion 18 engage the teeth 94 of the rack 82.

[0036] In the embodiment illustrated in FIG. 3A, only the teeth 94 of the rack 82 that are aligned with the counterwheel support surface 84 include the chamfered lead in portion 95, since only those teeth 94 of the rack 82 will come into contact with the chamfered lead in portion 44 of the teeth 40 of the pinion 80 when the pinion 18 comes into contact with the rack 82 upon axial extension of the shaft 122. In the example shown in FIG. 3A, six of the teeth 94 of the rack 82 include the chamfered lead in portion 95, while in the example shown in FIG. 11 nine of the teeth 94 of the rack 82 include the chamfered lead in portion 95, but it will appreciated that the number of teeth 94 of the rack 82 that include the chamfered lead in portion 95 may vary. It will also be appreciated that each of the teeth 94 of the rack 82 may include a chamfered lead in portion akin to the chamfered lead in portion 95 in some aspects. FIG. 3B shows a view of a pinion 18 and rack 82 when the teeth 40 of the pinion 18 are meshed with the teeth 94 of the rack 82, such that several teeth 40 of the pinion 18 are each positioned between two adjacent teeth 94 of the rack 82. As will be discussed in more detail below, when the teeth 40 of the pinion 18 are intermeshed withthe teeth 94 of the rack 82 as shown, for example, in FIG. 3B, the climbing robot 10 may travel up or down along the rack 82 in response to rotation of the pinion 18 in a corresponding direction.

[0037] In the exemplary embodiment illustrated in FIG. 4, cut outs 96, 98 are positioned where the counterwheels 19 of the climbing robot 10 engage the rack structure 80, thereby facilitating proper alignment of the teeth 40 of the pinion 18 with the teeth 94 of the rack 82. As shown in FIGS. 3B, the counterwheel support surfaces 84, 86 are provided as a vee-wheel track used to center the counterwheels 19 as will be described in greater detail. For example, counterwheel support surface 84 has a central flat bottom portion 85 (located between two peripheral chamfered portions 87a, 87b), which engages a mating surface 21 of a counterwheel 19 to set the pinion gear teeth engagement without bottoming out the pinion gear 18, and which serves as a lead in of pinion gear 18 into the rack 82. In some aspects, the chamfered portions 87a, 87b of the counterwheel support surface 84 mate with complementary chamfered portions 21 of the counterwheel 19 to center the counterwheel 19 in the groove provided by the counterwheel support surface 84 of the cutout 96, advantageously ensuring proper alignment of the pinion 18 and rack 82.

[0038] FIG. 4 shows a partial section view of an exemplary climbing robot 10, with racks 82, 82' and support rails 90, 90’ positioned on opposing sides of the climbing robot 10. The exemplary climbing robot 10 shown in FIG. 4 includes drive wheels 12, 12' supported by support rails 90, 90'. In some aspects, the climbing robot 10 engages the racks 82, 82' to climb vertically.

[0039] In certain embodiments, the wheels 12, 12' are independently driven by motors 120, 120' of the climbing robot 10. In the illustrated exemplary embodiment, the motors 120, 120' are shown grounded to the frame of robot 10, such that the motors 120, 120' transmit torque to the shafts 122, 122' via a spline or bushing 124, 124' where the pinions 18, 18' and counterwheels 19, 19' are coupled to the shafts 122, 122'. Similarly, the shafts 122, 122' transmit torque to the wheels 12, 12' via a hub, spline or bushing 126, 126'. The counterwheels 20, 20' are coupled to shafts 130, 130' respectively, with a trunnion 132 coupling shafts 122 and 130, and trunnion 132' coupling shafts 122' and 130'.

[0040] In the illustrated embodiment, the climbing robot 10 includes a motor 136 coupled to opposite hand lead screws 138, 138' such that rotation of the motor 136 causes the shafts 122, 130 to move in opposition to the shafts 122', 130' to selectively engage and disengage the racks 82, 82'. In certain embodiments, the counterwheels 19, 20 have mating surfaces 21, 31, respectively, thatengage counterwheel support surfaces 84, 86 that are provided as a vee-wheel track is used to center the vee-wheels or counterwheels 19, 20. In some aspects, after proper engagement of the teeth 40, 40’ of the pinions 18, 18’ with the teeth 94, 94’ of the racks 82, 82’, respectively, the motor 136 (which may be a servo motor) is disabled, and the lead screws 138, 138’ are allowed to back drive, such that the mating surfaces 21, 31 of the counterwheels 19, 20 engage and follow the counter wheel support surfaces 84, 86.

[0041] FIGS. 5-10 show various (e g., perspective, side elevational, and exploded views) of the shaft 122 and the pinion 18, which mounts to the shaft 122. With reference to FIG. 6, the exemplary shaft 122 includes a pinion mounting portion 160 at the forward end 123 of the shaft 122 for transmitting torque to the pinion 18. The shaft 122 also includes one or more splined portions 166 located between the pinion mounting portion 160 and a rear end 125 of the shaft 122. In the illustrated embodiment, the exemplary shaft 122 includes two splined portions 166 located on opposite sides of the shaft 122 (although the shaft 122 may include only one splined portion 166 or more than two splined portions 166 in other embodiments).

[0042] In the illustrated embodiment, a counterwheel adapter 164 (shown in FIGS. 6 and 8-10), which may be referred to herein as a “counterwheel support bushing,” serves as an intermediary member that enables the coupling of the counterwheel 19 with the pinion mounting portion 160 of the shaft 122. In some embodiments, the counterwheel adapter 164 includes internal splines 174 that mate with the complementary splined portions 166 of the shaft 122. In the embodiment illustrated in FIGS. 9 and 10, the exemplary counterwheel adapter 164 includes two opposing internal splines 174. In some aspects, instead of the counterwheel support bushing or adapter 164 being coupled directly to the pinion mounting portion 160 of the shaft 122 and to the counterwheel 19, the shaft 122 may include a counterwheel mounting portion being located rearwardly relative to the pinion mounting portion 160 and having a diameter that is larger than the diameter of the pinion mounting portion 160, such that the (internal circumference of) counterwheel 19 may couple (e.g., by friction fit) directly to the counterwheel mounting portion of the shaft 122.

[0043] In some embodiments, the counterwheel 19 is coupled to the counterwheel adapter 164 such that the counterwheel adapter 164 and the counterwheel 19 rotate together when the shaft 122 is rotated, and such that the counterwheel 19 does not rotate on the shaft 122 independently of the counterwheel adapter 164. In the illustrated embodiment, the exterior surface or circumference175 of the counterwheel adapter 164 is coupled to an interior surface or circumference 23 of the counterwheel 19 via a friction fit (although it will be appreciated that this coupling may be achieved via an intermeshing of interior splines of the counterwheel 19 and exterior splines of the counterwheel adapter 164.

[0044] In certain embodiments, the pinion 18 is coupled to the pinion mounting portion 160 of the shaft 122 via a one-way bearing 127, such that the pinion 18 interfaces with the shaft 122 via the one-way bearing 127. In the exemplary illustrated embodiment, the pinion 18 is secured to the counterwheel 19 and / or the counterwheel adapter or support bushing 164 via a retaining washer 167 and a retaining ring 169, with the retaining washer 167 being located rearwardly relative to the retaining ring 169 (and between the retaining ring 169 and the pinion 18), while the retaining ring 169 is located forwardly relative to the retaining washer 167.

[0045] In some aspects, when the pinion 18 moves into engagement with the rack 82 upon extension of the shaft 122 into the extended position (shown, for example, in FIGS. 15-18), while the shaft 122 does not rotate (since the motor 120 coupled to the shaft 122 is not yet activated), the one-way bearing 127 is configured to permit the pinion 18 to rotate in a first direction relative to the shaft 122, and this rotation is facilitated by the abutment of the opposing complementary chamfered lead in portions 44 of the teeth 40 of the pinion with the complementary chamfered lead in portions 95 of the teeth 94 of the rack 82, thus facilitating a proper alignment and intermeshing of the teeth 40 of the pinion 18 and the teeth 94 of the rack 82, and preventing the undesirable jamming of the teeth 40 of the pinion 18 against the teeth 94 of the rack 82. By the same token, during the engagement of the teeth 40 of the pinion 18 with the teeth 94 of the rack 82, the oneway bearing 127 is configured to prevent counter-rotation of the pinion 18 in a second direction opposite to the first direction. The one-way bearing 127 may be a one-way locking needle roller bearing clutch, although the one-way bearing 127 may be of any other suitable type.

[0046] As such, in certain aspects, when the shaft 122 is in the extended position and remains in a fixed position relative to its axis of rotation (i.e., the shaft 122 does not rotate), the pinion 18 rotates in the direction permitted by the one-way bearing 127) relative to the shaft 122 while being prevented by the one-way bearing 127 from rotating in an opposite direction relative to the shaft 122. This rotation of the pinion 18 during the initial engagement of the teeth 40 of the pinion 18 with the teeth 94 of the rack facilitates a proper alignment of the teeth 40 of the pinion 18 and theteeth 94 of the rack, which in turn permits the chamfered lead in portions 44 of the teeth 40 of the pinion 18 and the complementary chamfered lead in portions 95 of the teeth 94 of the rack 82 from jamming against each other, but instead enables the chamfered lead in portions 44 of the teeth 40 of the pinion 18 to slide (by virtue of their complementary orientation and chamfer slope) along the chamfered lead in portions 95 of the teeth 94 of the rack, such that the teeth 40 of the pinion are guided to slide in between (and properly intermesh with) the teeth 94 of the rack 82 (as shown, for example, in FIGS. 3A and 16).

[0047] As pointed out above, FIG. 4 shows a partial section view of an exemplary climbing robot 10 positioned between two opposing vertical racks 82, 82’ while the shafts 122, 122’ of the climbing robot 10 are retracted, and the pinions 18, 18’ coupled to the shafts 122, 122’ being spaced away from the racks 82, 82’ such that the teeth 40, 40’ of the pinions 18, 18’ are spaced apart from, and not in contact with the teeth 94, 94’ of the racks 82, 82’. FIG. 11 shows a perspective view of exemplary relative positions of the shaft 122 and the pinion 18 of the climbing robot 10 relative to the rack 82 when the shaft 122 and the pinion 18 are in a retracted orientation and spaced away from the rack 82. FIG. 12 shows a side elevational view of this position of the shaft 122 and pinion 18 relative to the rack 82. In some embodiments, in response to rotation of the lead screw 138 (which is actuated by the motor 136), the shaft 122 may be extended (e.g., axially along the axis of rotation of the shaft 122) from the retracted position toward an extended position, such that the shaft 122 and pinion 18 move in a direction toward the rack 82.

[0048] FIG. 13 shows a partial section view of the climbing robot 10 showing one side of the climbing robot 10 and one set of the racks 82 for clarity, and showing the shaft 122 in a partially extended position, where the pinion 18 just begins to engage the rack 82. FIG. 14 shows a perspective view of the pinion 18 just beginning to engage the rack 82. FIG. 15 shows a side elevational view of this position of the shaft 122 and pinion 18 relative to the rack 82.

[0049] In the state shown in FIGS. 13-15, the lead screw 138 is rotated (e.g., via actuation by the motor 136) such that the shaft 122 is extended in a direction along the axis of rotation of the shaft 122 in a direction toward the rack 82 to a position, where the pinion 18 is just about to engage with rack 82. In this position, the one-way bearing 127 permits rotational play between the pinion 18 and the shaft 122 such that the pinion 18 is permitted to rotate relative to the shaft 122 in a first direction (e.g., clockwise) to facilitate a proper alignment and intermeshing of the teeth 40 of thepinion with the teeth 94 of the rack 82 as mentioned above. As pointed out above, the one-way bearing 127 is configured such that rotation of the pinion 18 relative to the shaft 122 in a direction opposite to the first direction (e.g., counterclockwise) is restricted. In other words, the one-way bearing 127 permits the pinion 18 to rotate in a first direction during the initial engagement of the teeth 40 of the pinion 18 and the teeth 94 of the rack 82, advantageously facilitating the proper alignment of the lead in portions 44 of the teeth 40 of the pinion 18 with the lead in portions 95 of the teeth 94 of the rack 82, and reducing and / or eliminating potential misalignments of the teeth 40 of the pinion and the teeth 94 of the rack 82.

[0050] As pointed out above, in certain implementations, to further facilitate a proper intermeshing of the teeth 40 of the pinion with the teeth 94 of the rack 82 without jamming upon axial extension of the shaft 122, the teeth 40 of the pinion 18 may have a chamfered lead in portion 44 and some of the teeth 94 of the rack 82 (e.g., the teeth 94 of the rack 82 located along the cutout 96 of the rack structure 80) may have a complementary chamfered lead in portion 95. In one embodiment, when the shaft 122 is extended into the position shown in FIGS. 13-15, the shaft 122 is permitted by the one-way bearing 127 to rotate only in one direction (e.g., clockwise) as the chamfered lead in portions 44 of certain teeth 40 of the pinion 18 come into contact with the opposing lead in portions 95 of certain teeth 94 of the rack 82 having a chamfer that is complementary to the chamfer of the lead in portions 44 of the teeth 40 of the pinion 18, thereby facilitating the rotation of the pinion 18 relative to the shaft 122 and facilitating a proper alignment of the teeth 40 of the pinion 18 relative to the teeth 94 of the rack 82. Once the teeth 40 of the pinion 40 and the teeth 94 of the rack 82 are aligned, the teeth 40 slide in between adjacent teeth94 of the rack 82 while being guided by the complementarily-chamfered lead in portions 44 and95 of the teeth 40 and 94, respectively, thereby facilitating a proper intermeshing of the teeth 40 of the pinion with the teeth 94 of the rack 82, as shown, for example, in FIGS. 3B and 16.

[0051] FIG. 16 shows a perspective view of the pinion 18 engaging the rack 82 after the teeth 40 of the pinion 18 initially intermesh with the teeth 94 of the rack 92 and the shaft 122 is further moved away from the fully retracted position (shown in FIG. 4) toward the fully extended position (shown in FIGS. 18-20) such that the teeth 40 of the pinion 18 slide in further between the teeth 94 of the rack 94. FIG. 17 shows a side elevational view of this position of the shaft 122 and pinion 18 relative to the rack 82. When the pinion 18 and shaft 122 are in the position relative tothe rack 82 shown in FIGS. 16-17, the one-way bearing 127 still permits rotational play between the pinion 18 and the shaft 122 such that the pinion 18 is permitted to rotate relative to the shaft 122 in a first direction (e.g., clockwise) to ensure a proper alignment and intemieshing of the teeth 40 of the pinion with the teeth 94 of the rack 82 as mentioned above. On the other hand, the oneway bearing 127 restricts rotation of the pinion 18 relative to the shaft 122 in a direction opposite to the first direction (e.g., counterclockwise).

[0052] In some embodiments, in the event that the teeth 40 of the pinion 18 fail to properly engage and intermesh with the teeth 94 of the rack 82, a retry feature may be provided. Here, in the event there is an interference / overlap of the edges of the teeth 40 of the pinion 18 and the edges of the teeth 94 of the rack 82, the shaft 122 and pinion 82 may be retracted and rotated using the drive motor 120, and the pinion 18 may then be reinserted back into the rack 82. By way of example, the pinion 18 may be rotated slightly forward and then reinserted for a successful proper intermeshing of the teeth 40 of the pinion 18 with the teeth 94 of the rack 82. In some embodiments, the “engagement” sequence above may be reversed to disengage the teeth 40 of the pinion 18 from the teeth 94 of the rack 82.

[0053] FIG. 18 shows a partial section view of the climbing robot 10 showing one side of the climbing robot 10 and one set of the racks 82 for clarity, and showing the teeth 40 of the pinion 18 fully engaging the teeth 94 of the rack 82 while the shaft 122 is moved into the fully extended position. FIG. 19 shows a perspective view of the pinion 18 fully engaged to the rack 82 while the shaft 122 is in the fully extended position. FIG. 20 shows a side elevational view of this position of the shaft 122 and pinion 18 relative to the rack 82. In some embodiments, as the shaft 122 is moved from the “initial engagement” (and more retracted) position shown in FIGS. 13-17 to the “full engagement” (and more extended) position shown in FIGS. 18-20 in response to rotation of the lead screw 138 further from its previous position shown in FIG. 13.

[0054] In some embodiments, during the movement of the shaft 122 toward the “fully engaged” and fully extended position shown in FIGS. 19-20, the mating surfaces 21 of the counterwheel 19 come into contact first with the chamfered portions 87a, 87b of the counterwheel support surface 84 and then into contact with the flat bottom portion 85 of the counterwheel support surface 84, as shown in FIG. 19. In other words, in certain embodiments, the chamfered portions 87a, 87b of the counterwheel support surface 84 provide an initial mating surface that is complementary to themating surfaces 21 of the counterwheel 19, and ensure that the counterwheel 20 comes into the rack space at a correct location to facilitate a proper engagement of the teeth 40 of the pinions 18 with the teeth 94 of the rack 82. To put it another way, the chamfered portions 87a, 87b of the counterwheel support surface 84 mate with complementary chamfered portions 21 of the counterwheel 19 to center the counterwheel 19 in the groove provided by the counterwheel support surface 84, advantageously ensuring a proper alignment of the pinion 18 and rack 82.

[0055] In some embodiments, after the teeth 40 of the pinion 18 properly intermesh with the teeth 94 of the rack 82, the one-way bearing 127 locks and enables the pinion 18 to rotate with the shaft 122 in a second direction (e.g., counterclockwise) opposite to the first direction, thereby permitting the transfer of torque to the pinion 18 as a result of the spinning of the shaft 122 (which may be actuated by the motor 120, and allowing the climbing robot 10 to climb up the rack 82 via the continuous intermeshing of the teeth 40 of the pinion 18 with the teeth 94 of the rack 82. In one aspect, when the shaft 122 and pinion 18 of the climbing robot 10 are in the position shown in FIGS. 19-20, where the teeth 40 of the pinion 18 are fully engaged with the teeth 94 of the rack 82, the motor 120 of the robot 10 may be activated to apply torque to shaft 122 and pinion 18 such that the climbing robot 10 is raised along the rack 82, thereby separating the wheel 12 of the climbing robot 10 from the support rail 90.

[0056] As mentioned above, in some embodiments, after the teeth 40 of the pinion 18 properly engage the teeth 94 of the rack 82, the one-way bearing 127 locks, preventing the rotation of the pinion 18 relative to the shaft 122 in a second direction opposite to the first direction, thereby permitting the transfer of torque to the pinion 18 as a result of the spinning of the shaft 122 (which may be actuated by the motor 120), and allowing the climbing robot 10 to climb vertically along the rack 82 (by way of the climbing movement of the pinion 18 along the rack 82, which is facilitated by the intermeshing of the teeth 40 of the pinion 18 with the teeth 94 of the rack 82).

[0057] The above-described exemplary embodiments provide a climbing robot that can move vertically along a toothed rack, and that includes a pinion that is mounted on the drive shaft via a one way bearing, enabling the pinion to move in one direction during the initial engagement of the teeth of the pinion with the teeth of the rack to ensure proper engagement of the teeth of the pinion with the teeth of the rack while avoiding the undesired jamming of the teeth of the pinion againstthe teeth of the rack. As such, the climbing robot described herein is advantageously less likely to encounter misalignments and / or improper loading of the pinion onto the complementary rack.

[0058] The foregoing detailed description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the description to the precise fomi disclosed. Many modifications and variations are possible in light of the above teaching. The described embodiments were chosen in order to best explain the principles of the claimed system and its practical application to thereby enable others skilled in the art to best utilize the claimed system in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the method be defined by the claims appended hereto.

Claims

CLAIMSWhat is claimed is:

1. A mobile robot configured to travel in a vertical or inclined passage comprising a rack including teeth, the mobile robot comprising: a hub for mounting a wheel; a shaft engaged to the hub and configured to be rotated about an axis of rotation by a motor, the shaft further configured to be extended axially along the axis of rotation from a retracted position to an extended position; a pinion mounted on an end of the shaft, the pinion including teeth configured to mesh with the teeth of the rack and to move into engagement with the rack upon extension of the shaft into the extended position; and a one-way bearing coupled to the shaft and to the pinion such that the pinion interfaces with the shaft via the one-way bearing, wherein the one-way bearing is configured to: permit the pinion to rotate relative to the shaft in a first direction to prevent jamming of the teeth of the pinion against the teeth of the rack when the pinion moves into engagement with the rack upon extension of the shaft into the extended position; and prevent rotation of the pinion in a second direction opposite to the first direction.

2. The mobile robot of claim 1, wherein the one-way bearing is configured to permit the pinion to rotate in the first direction when the shaft is in the extended position while the shaft does not rotate.

3. The mobile robot of claim 1, wherein the one-way bearing is configured to permit the shaft to rotate in the second direction together with the one-way bearing and the pinion.

4. The mobile robot of claim 1, wherein the one-way bearing is coupled to the shaft such that the one-way bearing moves axially along the axis of rotation upon the extension of the shaft into the extended position.

5. The mobile robot of claim 1, wherein each of the teeth of the pinion comprises a chamfered lead in portion configured to facilitate rotation of the pinion and meshing engagement of the teeth of the pinion with the teeth of the rack without jamming upon axial extension of the shaft.

6. The mobile robot of claim 5, wherein each of the teeth of the rack comprises a chamfered lead in portion opposing and complementary to the chamfered lead in portion of each of the teeth of the pinion and configured to facilitate the rotation of the pinion and the meshing engagement of the teeth of the pinion with the teeth of the rack without jamming upon the axial extension of the shaft.

7. The mobile robot of claim 1, wherein the mobile robot is configured to move up or down within the passage by the rotation of the pinion against the rack.

8. An order fulfilment system, comprising: a multilevel storage structure having storage locations in different levels, and a vertical or inclined passage extending between the different levels, the passage comprising a rack including teeth; and a mobile robot configured to travel between the levels in the passage, the mobile robot including: a hub for mounting a wheel; a shaft engaged to the hub and configured to be rotated about an axis of rotation by a motor, the shaft further configured to be extended axially along the axis of rotation from a retracted position to an extended position; a pinion mounted on an end of the shaft, the pinion including teeth configured to mesh with the teeth of the rack and to move into engagement with the rack upon extension of the shaft into the extended position; and a one-way bearing coupled to the shaft and to the pinion such that the pinion interfaces with the shaft via the one-way bearing, wherein the one-way bearing is configured to: permit the pinion to rotate relative to the shaft in a first direction toprevent jamming of the teeth of the pinion against the teeth of the rack when the pinion moves into engagement with the rack upon extension of the shaft into the extended position; and prevent rotation of the pinion in a second direction opposite to the first direction.

9. The order fulfilment system of claim 8, wherein the one-way bearing is configured to permit the pinion to rotate in the first direction when the shaft is in the extended position while the shaft does not rotate.

10. The order fulfilment system of claim 8, wherein the one-way bearing is configured to permit the shaft to rotate in the second direction together with the one-way bearing and the pinion.

11. The order fulfilment system of claim 8, wherein the one-way bearing is coupled to the shaft such that the one-way bearing moves axially along the axis of rotation upon the extension of the shaft into the extended position.

12. The order fulfilment system of claim 8, wherein each of the teeth of the pinion comprises a chamfered lead in portion configured to facilitate rotation of the pinion and meshing engagement of the teeth of the pinion with the teeth of the rack without jamming upon axial extension of the shaft.

13. The order fulfilment system of claim 12, wherein each of the teeth of the rack comprises a chamfered lead in portion opposing and complementary to the chamfered lead in portion of each of the teeth of the pinion and configured to facilitate the rotation of the pinion and the meshing engagement of the teeth of the pinion with the teeth of the rack without jamming upon the axial extension of the shaft.

14. The order fulfilment system of claim 8, wherein the mobile robot is configured to move up or down within the passage by the rotation of the pinion against the rack.

15. A method of transporting a mobile robot along a vertical or inclined passage comprising a rack including teeth, the method comprising: extending a pinion including teeth of the mobile robot from a first position spaced from the rack to a second position where the teeth of the pinion engage with the teeth of the rack, wherein the pinion is mounted to a shaft configured to be rotated about an axis of rotation by a motor and to be extended axially along the axis of rotation from a retracted position to an extended position; rotating, after extension of the shaft into the extended position, the shaft and pinion by a motor, the shaft rotating by a force exerted by the motor on the shaft; and preventing jamming of the teeth of the pinion against the teeth of the rack when the pinion moves into the second position to engage the teeth of the rack upon extension of the shaft into the extended position by providing a one-way bearing coupled to the shaft and to the pinion such that the pinion interfaces with the shaft via the one-way bearing, wherein the one-way bearing is configured to: permit the pinion to rotate relative to the shaft in a first direction; and prevent rotation of the pinion in a second direction opposite to the first direction.

16. The method of claim 15, further comprising, permitting, via the one-way bearing, the pinion to rotate in the first direction when the shaft is in the extended position while the shaft does not rotate.

17. The method of claim 15, further comprising, permitting, via the one-way bearing, the shaft to rotate in the second direction together with the one-way bearing and the pinion.

18. The method of claim 15, wherein the one-way bearing is coupled to the shaft such that the one-way bearing moves axially along the axis of rotation upon the extension of the shaft into the extended position.

19. The method of claim 15, wherein each of the teeth of the pinion comprises a chamfered lead in portion configured to facilitate rotation of the pinion and meshing engagement of theteeth of the pinion with the teeth of the rack without jamming upon axial extension of the shaft.

20. The method of claim 19, wherein each of the teeth of the rack comprises a chamfered lead in portion opposing and complementary to the chamfered lead in portion of each of the teeth of the pinion and configured to facilitate the rotation of the pinion and the meshing engagement of the teeth of the pinion with the teeth of the rack without jamming upon the axial extension of the shaft.

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