Container Handling System

Abstract

Container Handling System A load handling device is provided for lifting and moving storage containers arranged in a stack within a storage structure, the storage structure comprising a track structure above the stack of storage containers. The load handling device comprises a body, a drive assembly configured to move the body on the track structure, and a container handling system. The container handling system comprises: i) a holding frame; ii) a holding assembly mounted on the holding frame, the holding assembly configured to releasably hold a storage container in a holding area relative to the holding frame; iii) a lifting assembly configured to lower and raise the holding frame relative to the body; and iv) an overheight detection system comprising object detection means mounted on the holding frame, the object detection means configured to detect the presence of an object in the overheight area, where the overheight area is above the holding area.

Description

[Technical Field]

[0001] The present invention relates to a device for handling storage containers in a storage and retrieval system. [Background technology]

[0002] Some commercial and industrial activities require a system that allows for the storage and retrieval of a large number of different products. WO2015019055A1 describes a storage and retrieval system in which items are stored in storage containers, and the storage containers are arranged in stacks within a grid storage structure. The system further comprises remotely operated load handling devices configured to travel on tracks located on top of the grid storage structure. To pick up or drop off storage containers stored within the grid storage structure, each load handling device is equipped with a gripper device for releasably holding the storage container and a lifting assembly for raising and lowering the gripper device.

[0003] Objects that are not loaded into a storage container in an expected manner can cause problems within the storage and retrieval system. For example, a situation can arise where an object protrudes above the top of a storage container. The protruding item can cause several problems, such as preventing a gripper device from properly engaging the storage container and preventing the storage container from being properly received by a load handling device, as well as downstream problems, such as the storage container becoming stuck in another area of ​​the storage and retrieval system.

[0004] The present invention aims to address the problem of storage containers containing protruding items in storage and retrieval systems. Summary of the Invention

[0005] The invention is defined in the appended claims.

[0006] The present invention also provides a container handling system comprising a holding frame, a holding assembly mounted to the holding frame, wherein the holding assembly is configured to releasably hold a storage container in a holding area relative to the holding frame, and an overheight detection system comprising object detection means mounted to the holding frame, wherein the object detection means is configured to detect the presence of an object in the overheight area, wherein the overheight area is above the holding area.

[0007] The over-height area may be substantially planar. The over-height area may be a substantially horizontal plane. This helps to minimise the possibility of falsely detecting an object within the holding area (i.e. within the storage container). The object detection means may be configured to detect the presence of an object between at least two points in the horizontal plane. The over-height area may be in a fixed position relative to the holding frame. The object detection means may be configured to detect an object extending from the holding area into or through the over-height area.

[0008] The holding area may be in a fixed position relative to the holding frame. The holding assembly may be configured to releasably hold the storage container from above. The holding area may be below the holding frame. The holding frame and holding assembly may be configured to define an upper limit of the holding area. In other words, the holding frame and holding assembly may be configured such that a storage container held by the holding assembly cannot move upward relative to the holding frame beyond the upper limit due to being physically blocked by components of the holding frame. The holding frame may include one or more frame members arranged in a substantially horizontal plane. The holding frame may have a rectangular shape. The holding area may be below the frame members. The upper limit of the holding area may be the lowermost surface of the frame members. The overheight area may be above the lowermost surface of the frame members.

[0009] The retaining frame may comprise a frame opening extending vertically through the retaining frame. At least a portion of the overheight region may be located within the frame opening. The overheight region may be entirely within the frame opening. At least a portion of the overheight region may be located above the frame opening. The overheight region may be entirely above the frame opening. At least a portion of the object detection means may be mounted within the retaining frame opening. At least a portion of the object detection means may be mounted above the frame opening. The object detection means may be configured to detect objects extending from the retaining region into or through the frame opening.

[0010] The object detection means may include sensor assemblies disposed on opposite sides of the over-height region. If the holding frame includes a frame opening, the sensor assemblies may be disposed on opposite sides of the frame opening. The sensor assemblies may include one or more photoelectric sensors. The sensor assemblies may include a through-beam sensor configuration. The sensor assemblies may include a retro-reflective sensor configuration.

[0011] The sensor assembly may include at least one transmitter and at least one receiver mounted on a support frame on opposite sides of the over-height region. The at least one transmitter may be configured to emit a signal to the at least one receiver. The at least one receiver may be configured to detect a signal from the at least one transmitter. The over-height detection system may further include a controller communicatively coupled to the at least one transmitter and the at least one receiver. The controller may be configured to determine that an object is in the over-height region when a signal between the at least one transmitter and the at least one receiver is interrupted.

[0012] The sensor assembly may include at least one transmitter and at least one receiver mounted on a holding frame on the same side of the over-height region and at least one reflector on an opposing side of the over-height region. The at least one transmitter is configured to emit a signal toward the at least one reflector, and the at least one receiver is configured to detect the signal from the at least one transmitter after it has been reflected by the at least one reflector. The over-height detection system may further include a controller communicatively coupled to the at least one transmitter and the at least one receiver. The controller may be configured to determine that an object is in the over-height region when a signal between the at least one transmitter and the at least one receiver via the at least one reflector is interrupted.

[0013] The object detection means may comprise a camera mounted on the holding frame. The camera may be configured to capture an image including the over-height region. The object detection means may further comprise one or more processors configured to analyze the image and determine the presence of an object within the over-height region.

[0014] The object detection means may comprise a substantially horizontal sheet defining the over-height region. The object detection means may be configured to detect a force being applied to the horizontal sheet to determine the presence of an object in the over-height region. The object detection means may comprise a mechanical force sensor.

[0015] The container handling system may further include a lifting assembly configured to lower and raise the support frame.

[0016] The lifting assembly may include at least one tether and at least one motor or other winding and unwinding means. The at least one tether may be coupled (directly or indirectly) between the holding frame and the at least one motor. The at least one motor may be configured to wind and unwind the at least one tether to raise and lower, respectively, the holding frame.

[0017] The container handling system may further comprise a control system comprising one or more controllers configured to control operation of the holding assemblies based on detection results by the object detection means, and the control system may be configured to prevent activation of the holding assemblies if the object detection means detects the presence of an object in the over-height region.

[0018] If the container handling system includes a lifting assembly, the control system may be configured to activate the overheight detection system (i.e., activate the object detection means) when the lifting assembly is lowering the holding frame or after the lifting assembly has lowered the holding frame to a predetermined position.

[0019] If the container handling system includes a lifting assembly, the control system may be configured to control the lifting assembly to raise the holding frame without actuating the holding assembly when the object detection means detects the presence of an object in the excess height region.

[0020] The excess height detection system may be configured to determine the height of an object protruding above the storage container based on the vertical distance lowered by the holding frame during the period between when the object is first detected in the excess height area and when the storage container is in the holding area.

[0021] The holding assembly may include a plurality of grippers mounted on a holding frame, each gripper being movable between an engaging position and a disengaging position for respectively engaging and disengaging a storage container.

[0022] The present invention also provides a load handling device for lifting and moving storage containers arranged in a stack within a storage structure, the storage structure comprising a track structure above the stack of storage containers, the load handling device comprising a body, a drive assembly configured to move the body on the track structure, and a container handling system having a lifting assembly as defined above, wherein the lifting assembly is configured to lower and raise a holding frame relative to the body.

[0023] The load handling device may further comprise a container accommodating space configured to accommodate a storage container held by the holding frame, and the lifting assembly may be configured to raise and lower the holding frame into and out of the container accommodating space, respectively.

[0024] The track structure may be a track structure comprising a first set of tracks and a second set of tracks, the first set of tracks extending in a first direction and the second set of tracks extending in a second direction, the second direction being substantially perpendicular to the first direction to form a grid pattern defining a plurality of grid cells. The drive assembly may be configured to move the body of the load handling device on the track structure.

[0025] The present invention also provides a storage and retrieval system, comprising a storage structure, a stack of a plurality of storage containers, each storage container having an upper opening through which an object can be placed in the storage container, and a track structure positioned above the stack of storage containers and configured to allow access to each stack from above, the storage and retrieval system further comprising at least one cargo handling device as defined above, wherein the container handling system is configured to pick up storage containers from the stack of storage containers and drop off storage containers onto the stack of storage containers.

[0026] The track structure may include a first set of tracks and a second set of tracks, the first set of tracks extending in a first direction and the second set of tracks extending in a second direction, the second direction being substantially perpendicular to the first direction to form a grid pattern defining a plurality of grid cells, and each stack of storage containers may be positioned beneath a grid cell.

[0027] The storage and retrieval system may further include a central control system configured to communicate with at least one load handling device. The central control system may be configured to instruct the load handling device to move to a target grid cell from a list of available grid cells and pick up or drop off a storage container below the target grid cell. The central control system may be further configured to remove the target grid cell from the list of available grid cells if the excess height detection system detects an object within an excess height region when the load handling device is at the target grid cell.

[0028] The present invention also provides a method of using the container handling system defined above, the method comprising the steps of lowering a holding frame towards a storage container, detecting whether an object is present in the excess height region, and if an object is detected, raising the holding frame away from the storage container without activating the holding assembly, and if no object is detected, activating the holding assembly to hold the storage container and then raising the holding frame. [Brief explanation of the drawings]

[0029] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which like reference numerals are used to refer to like features, and in which: [Figure 1] FIG. 1 is a schematic perspective view of a grid storage structure and a container disposed within the grid storage structure. [Figure 2] FIG. 2 is a schematic plan view of a track structure on top of the storage structure of FIG. [Figure 3] FIG. 3 shows a load handling device on top of the truck structure of the storage structure of FIG. [Figure 4] FIG. 4 is a schematic perspective view of a load handling device having a retaining frame in position below the bottom of the load handling device. [Figure 5] FIG. 5 is a schematic perspective view of the load handling device of FIG. 4 with the side panels removed to show the container receiving space. [Figure 6] FIG. 6 is a schematic perspective view of the load handling device of FIG. 5, with a container occupying the container receiving space. [Figure 7] FIG. 7 is a perspective view of a container handling system including a lifting assembly and a holding frame. [Figure 8A] FIG. 8A is a front perspective view of the gripper assembly in a closed configuration. [Figure 8B] FIG. 8B is a front perspective view of the gripper assembly in the open configuration. [Figure 9A]FIG. 9A is a rear perspective view of the gripper assembly of FIG. 8A. [Figure 9B] FIG. 9B is a rear perspective view of the gripper assembly of FIG. 8B. [Figure 10] FIG. 10 is a perspective view of a storage container that may be held by a holding frame of a container handling system. [Figure 11A] FIG. 11A is a side view of the holding frame and storage container, respectively, with the gripper assembly disengaged. [Figure 11B] FIG. 11B is a side view of the holding frame and storage container, respectively, with the gripper assembly engaged with the storage container. [Figure 12] FIG. 12 is a perspective view of a holding frame that holds a storage container. [Figure 13] FIG. 13 is a schematic perspective view of a holding frame for holding storage containers and an exemplary object detection means of a container handling system. [Figure 14] FIG. 14 is a schematic cross-sectional view of the example of FIG. 13 with an over-height object in the storage container. [Figure 15] FIG. 15 is a schematic perspective view of a holding frame for holding storage containers and another exemplary object detection means for a container handling system. [Figure 16] FIG. 16 is a schematic perspective view of a holding frame for holding storage containers and another exemplary object detection means for a container handling system. [Figure 17] FIG. 17 is a schematic bottom perspective view of an alternative support frame for a container handling system. [Figure 18] FIG. 18 is a block diagram of the control system. DETAILED DESCRIPTION OF THE INVENTION

[0030] FIG. 1 illustrates an exemplary storage structure 1 that may be used in a storage and retrieval system to store storage containers 50. The storage structure 1 includes a storage framework comprising upright members 3 and horizontal members 5, 7 supported by the upright members 3. The horizontal members 5 extend parallel to each other and to the illustrated x-axis. The horizontal members 7 extend parallel to each other and to the illustrated y-axis and transversely to the horizontal members 5. The upright members 3 extend parallel to each other and to the illustrated z-axis and transversely to the horizontal members 5, 7. The horizontal members 5, 7 form a grid pattern that defines a plurality of grid cells. In the illustrated example, the storage containers 50 are arranged in stacks 11 below the grid cells 14 defined by the grid pattern, one stack 11 of storage containers 50 per grid cell.

[0031] FIG. 2 shows an enlarged plan view of a section of a track structure 13 that forms part of the storage structure 1 illustrated in FIG. 1 and is located on top of the horizontal members 5, 7 of the storage structure 1 illustrated in FIG. 1. The track structure 13 may be provided by the horizontal members 5, 7 themselves (e.g., formed in or on the surfaces of the horizontal members 5, 7) or by one or more additional components attached to the top of the horizontal members 5, 7. The illustrated track structure 13 comprises x-direction tracks 17 and y-direction tracks 19, i.e., a first set of tracks 17 extending in the x-direction and a second set of tracks 19 extending in the y-direction that are transverse to the tracks 17 in the first set of tracks 17. The tracks 17, 19 define apertures 15 in the centers of the grid cells. The apertures 15 are sized to allow storage containers 50 located below the grid cells 14 to be lifted and lowered through the apertures 15. The x-direction tracks 17 are provided in pairs separated by channels 21, and the y-direction tracks 19 are provided in pairs separated by channels 23. Other arrangements of the track structure are possible.

[0032] Figure 3 shows multiple load handling devices 25 moving across the top of the storage structure 1 illustrated in Figure 1. The load handling devices 25, which may also be referred to as "bots," are provided with sets of wheels for engaging with corresponding x-direction tracks 17 or y-direction tracks 19 to enable the bots 25 to move across the track structure 13 and reach particular grid cells 14. The illustrated pairs of tracks 17, 19 separated by channels 21, 23 enable the bots 25 to occupy (or pass each other through) adjacent grid cells 14 without colliding with each other.

[0033] 4, the bot 25 comprises a body 27 having one or more components therein or attached thereto that enable the bot 25 to perform its intended functions. These functions may include traveling throughout the storage structure 1 on the track structure 13 and raising or lowering storage containers 50 (e.g., from or to stacks 11) so that the bot 25 can retrieve or place storage containers 50 at specific locations defined by the grid pattern.

[0034] The illustrated bot 25 includes a drive assembly comprising a first set of wheels 29 and a second set of wheels 31, which are attached to the body 27 of the bot 25 and enable the bot 25 to move in the x and y directions along the tracks 17 and 19, respectively. In particular, two wheels are provided on the short side of the bot 25 visible in FIG. 4, and two additional wheels 29 are provided on the opposite short side of the bot 25. The wheels 29 engage with the tracks 17 and are rotatably attached to the body 27 of the bot 25, enabling the bot 25 to move along the tracks 17. Similarly, two wheels 31 are provided on the long side of the bot 25 visible in FIG. 4, and two additional wheels 31 are provided on the opposite long side of the bot 25. The wheels 31 engage with the tracks 19 and are rotatably attached to the body 27 of the bot 25, enabling the bot 25 to move along the tracks 19.

[0035] To enable the bot 25 to move in first and second directions on different wheels 29, 31, the drive assembly further includes a wheel positioning mechanism (not shown) for selectively engaging the first set of wheels 29 with the first set of tracks 17 or the second set of wheels 31 with the second set of tracks 19. The wheel positioning mechanism is configured to raise and lower the first set of wheels 29 and / or the second set of wheels 31 relative to the body 27, thereby enabling the load handling device 25 to selectively move in either the first direction or the second direction across the tracks 17, 19 of the storage structure 1.

[0036] The wheel positioning mechanism can include one or more linear actuators, rotary components, or other means for raising and lowering at least one set of wheels 29, 31 relative to the body 27 of the bot 25 to move the at least one set of wheels 29, 31 off of and into contact with the tracks 17, 19. In some examples, only one set of wheels is configured to raise and lower, such that the act of lowering one set of wheels can effectively lift the other set of wheels off of the corresponding tracks, while the act of raising one set of wheels can effectively lower the other set of wheels into contact with the corresponding tracks. In other examples, both sets of wheels can be raised and lowered, which advantageously means that the body 27 of the bot 25 remains at substantially the same height, and therefore the weight of the body 27 and components mounted thereon does not need to be raised and lowered by the wheel positioning mechanism.

[0037] 4 also schematically illustrates a container handling system 100 for holding and transporting storage containers 50 between different locations within the storage structure 1. The container handling system 100 comprises a holding frame 110 for releasably holding the storage containers 50, and a lifting assembly 102 coupled to the holding frame 110 and configured to lower and raise the holding frame 110 relative to the body 27 of the bot 25. Further details of the container handling system 100 will be described later.

[0038] 5 and 6, the side panels of the bot 25 are omitted from the illustration so that the interior of the bot 25 can be seen. The illustrated body 27 of the bot 25 has an upper portion 41 and a lower portion 43. The upper portion 41 is configured to house or support one or more operating components (not shown), such as components of the lifting assembly 102 (e.g., motors), wireless communication components, and one or more processors for controlling the operation of the bot 25. The lower portion 43 is disposed below the upper portion 41. The lower portion 43 is open to the outside at the bottom and defines a container accommodating space 45 for accommodating at least a portion of a storage container 50 lifted into the container accommodating space 45 by the holding frame 110 and the lifting assembly 102. FIG. 5 shows the container accommodating space 45 before it is occupied by the storage container 50, and FIG. 6 shows the container accommodating space 45 after it is occupied by the storage container 50. The container receiving space 45 is sized so that the storage container 50 can fit sufficiently within the cavity 45 to allow the bot 25 to move across the track structure 13 on top of the storage structure 1 without the underside of the container 50 getting caught on the track structure 13 or another part of the storage structure 1. Once the bot 25 reaches its intended destination, the lifting assembly 102 lowers the holding frame 110 and corresponding container 50 out of the container receiving space 45 and to its intended location. The intended location may be an exit point for the stack 11 of storage containers 50 or the storage structure 1 (or an entrance point for the storage structure 1 if the bot 25 moves to collect a storage container 50 for storage therein). In the illustrated example, the upper portion 41 and lower portion 43 are separated by a physical partition; however, in other examples, the upper portion 41 and lower portion 43 may not be physically separated by a particular component or part of the body 27 of the bot 25. The upper and lower configuration of the bot 25 allows the bot 25 to occupy only a single grid cell 14 on the track structure 13 of the storage system 1.

[0039] In an alternative embodiment, the container accommodation space 45 of the bot 25 may not be within the body 27 of the bot 25. For example, the container accommodation space 45 may instead be adjacent to the body 27 of the bot 25, e.g., in a cantilever arrangement with the weight of the body 27 of the bot 25 balancing the weight of the container 50 being lifted. In such an embodiment, the support structure of the lifting assembly 102 may protrude horizontally from the body 27 of the bot 25, and the lifting assembly 102 may be configured to lower and raise the holding frame 110 relative to the support structure to lower and raise the storage container 50 into the container accommodation space 45 adjacent the body 27.

[0040] FIG. 7 illustrates an exemplary container handling system 100 for use with the bot 25 . The container handling system 100 includes a support frame 110 and a lifting assembly 102 .

[0041] The lifting assembly includes four tethers 104 connected at their upper ends to respective spools 106 and at their lower ends to the holding frame 110 (although FIG. 7 shows the tethers 104 disconnected from the holding frame 110). The tethers 104 may be in the form of cables, ropes, tapes, or any other form of tether having the physical properties necessary to lift the storage container 50. The tethers 104 may be wound up or unwound as needed to raise or lower the holding frame 110 assembly. One or more motors 108 or other winding and unwinding means are provided to effect or control the rotation of the spools 106 to wind up or unwind the tethers 104. The container handling system 100 is not limited to the particular lifting assembly shown in FIG. 7; other devices suitable for raising and lowering the holding frame 110 may be used.

[0042] The retaining frame 110 is formed as an open rectangular frame. In particular, the retaining frame includes four elongated frame members 112 arranged to form a rectangular frame that defines a central rectangular frame opening 114. In use, the retaining frame 110 is oriented such that the frame members 112 lie in a substantially horizontal plane and the frame opening 114 extends vertically through the retaining frame 110.

[0043] The holding frame further comprises a holding assembly 120 configured to engage with an engaging structure of the storage container 50 to releasably hold the container 50 from above. In this example, the holding assembly 120 comprises two gripper assemblies 122 mounted on the two frame members 112 at opposite ends of the holding frame 120.

[0044] 8A and 8B show a front view of the gripper assembly 122 alone. The gripper assembly 122 includes two grippers 124. Each gripper 124 includes a pair of legs 126. Each leg 126 is pivotally mounted at one end on the frame member 112 for rotational movement in a vertical plane, and each leg 126 includes a foot 128 at the other end. The legs 126 extend below the frame member 112 such that the feet 128 are located below the frame member 112. Each pair of legs 126 is rotatable between a closed position ( FIG. 8A ), in which the legs 128 are closer together, and an open position ( FIG. 8B ), in which the legs 128 are further apart.

[0045] 9A and 9B show the gripper assembly 122 from the rear when the gripper 124 is in the closed and open positions, respectively. The pairs of legs 126 are driven between the closed and open positions by linear actuators 130 and linkage assemblies 132 coupled between the linear actuators and each pair of legs 126.

[0046] FIG. 10 illustrates an exemplary storage container 50 that may be held by a holding frame 110 . Storage container 50 includes a base 51 and side walls 52 extending upwardly from base 51 to form a rectangular parallelepiped storage container having a top opening 56 through which objects can be placed into or removed from storage container 50. Storage container 50 further includes a rim 53 at the top of side walls 52. Rim 53 includes engagement structure 54 for engaging grippers 124 of holding frame 120. In this example, engagement structure is an aperture 54 extending vertically through rim 53.

[0047] 11A and 11B are side views of the holding frame 110 and storage container 50, showing how the grippers 124 interact with the apertures 54 to hold and release the storage container 50. Each aperture 54 is large enough horizontally to receive the respective gripper 124 when the gripper 124 is in the closed position, but not when the gripper 124 is in the open position. FIG. 11A shows the holding frame 110 in a position above the storage container 50, with the grippers 124 in the closed position and received through the apertures 54 until their feet 128 are positioned below the underside of the rim 53. FIG. 11B shows the grippers 124 after they have been moved to the open position. In the open position, the feet 128 of the grippers 124 can engage the underside of the rim 53 of the storage container 50. Thus, the holding frame 110 is then lifted upward by the lifting assembly 102, thereby lifting the storage container 50 along with the holding frame 110.

[0048] To hold and lift a storage container 50 using the container handling system 100, the following operations may be performed: The holding frame 110 is lowered by the lifting assembly 102 toward the top of the storage container 50 with the grippers 124 in the closed position until the grippers 124 are received within their respective apertures 54 in the rim 53 and the feet of the grippers 124 are below the underside of the rim 53. The grippers 124 are then moved to the open position so that the feet 128 can engage the underside of the rim 53. The lifting assembly 102 then raises the holding frame 110, causing the feet 28 to engage the rim 53, thereby lifting the storage container 50 along with the holding frame 110. To lower and release the storage container 50, the above operations are reversed.

[0049] To facilitate alignment of the holding frame 110 with the storage container 50 such that the grippers 124 are received within the apertures 54 of the storage container 50, four positioning members 116 are attached to the four corners of the holding frame 110. The positioning members 116 extend downwardly below the frame members 112. The storage container 50 further includes notches 55 (or other forms of recesses) in the corners of the storage container 50 to receive the positioning members 116. The positioning members 116 are configured (e.g., tapered) to allow the holding frame 110 to self-align with the storage container 50 as the holding frame 110 is lowered toward the storage container 50.

[0050] To enable the container handling system 100 to determine when the storage container 50 is close enough to the storage container 50 to release the grippers 124, the holding frame 110 may include one or more proximity sensors 117 mounted on the holding frame 110 that are configured to detect the vertical distance between the holding frame 110 and the top (i.e., rim 53) of the storage container 50 as the holding frame 110 is being lowered by the lifting assembly 102. When the proximity sensors 117 detect that the top of the storage container 50 is a certain predetermined distance from the holding frame, the lifting assembly 102 can stop lowering the holding frame 110 toward the storage container 50, and the holding assembly 120 can be actuated to engage the storage container 50. Any suitable proximity sensor 117 known in the art can be used, such as an ultrasonic sensor.

[0051] FIG. 12 is a schematic perspective view showing the holding frame 110 engaged with a storage container 50. The storage container 50 occupies a holding area below the holding frame 110. The holding area is the area occupied by the storage container 50 when the holding assembly 120 holds it. In other words, the holding assembly 120 can engage with the storage container 50 when it is in the holding area. The holding frame 110 (i.e., the arrangement of the holding members 112) in this example is sized to have approximately the same horizontal footprint as the storage container 50 so that upward movement of the storage container 50 relative to the holding frame 110 is physically limited by the frame members 112. Notably, when held by the holding frame 110, the top of the storage container 50 can be positioned no higher than the bottom of the frame members 112. Thus, in this example, the approximate upper limit of the holding area can be considered to be the plane coinciding with the bottommost surface of the frame members 112.

[0052] When the storage container 50 is in the holding area, the frame opening 114 of the holding frame 110 is positioned above the top opening 56 of the storage container 50 and is in communication with the top opening 56, so that objects can be placed in or removed from the storage container 50 through the top opening 56.

[0053] As described above, storage container 50 may be used to store objects. A situation may arise in which an object of excessive height protrudes above the top of storage container 50. By providing frame opening 114 in holding frame 110, when holding frame 110 is lowered towards storage container 50, any object of excessive height is likely to protrude through frame opening 114 rather than colliding with holding frame 110, which may, for example, cause holding frame 110 to become displaced from storage container 50.

[0054] The holding frame 110 further comprises an over-height detection system 140 having object detection means for detecting when an object is present in an over-height region 142 (shown below in FIG. 14). The overheight region 142 is in a fixed position relative to the holding frame 110 and is above the holding area; i.e., the overheight region 140 is above the top of the storage container 50 when the storage container 50 is held by the holding assembly 120. Thus, the overheight detection system 140 can be used to detect when an object protrudes above the top of the storage container 50. The vertical distance between the overheight region 142 and the holding area can be selected depending on how high an object can protrude above the top of the storage container 50 before it becomes a problem. The overheight region 142 can be directly above the holding area to detect any overheight objects, or the overheight region 142 can be vertically spaced apart from the holding area to detect any overheight objects that protrude beyond a threshold height above the holding area.

[0055] 13 is a simplified schematic diagram showing a holding frame 110 holding storage containers 50 in a holding area. In this example, the object detection means comprises a sensor assembly 143 including a plurality of infrared transmitters 144 attached to frame members 112 on one side of a frame opening 114 and a plurality of infrared receivers 146 attached to opposing frame members 112 on opposite sides of the frame opening 114. The infrared transmitters 144 are configured to emit infrared radiation across the frame opening 114 towards the infrared receivers 146, and the infrared receivers 146 are configured to detect the infrared radiation emitted from the infrared transmitters 144.

[0056] Sensor assembly 143 defines an overheight region 142 (depicted later in FIG. 14 ) that extends between transmitter 144 and receiver 146. In this example, transmitter 144 and receiver 146 are disposed in a substantially horizontal plane within frame opening 114, and thus overheight region 142 in this example is a substantially horizontal plane located within frame opening 114.

[0057] FIG. 14 shows a schematic cross-sectional view of the holding frame 110 that holds the storage container 50 in the holding area. Considering that the frame opening 114 is located above the storage container 50 and the sensor assembly 143 is disposed within the frame opening 114, the over-height region 142 is located directly above the top opening 56 of the storage container 50 when the storage container 50 is within the holding area. FIG. 14 also shows an over-height object 58 located within the storage container 50. The over-height object 58 protrudes above the top of the storage container 50 such that the over-height object 58 extends through the over-height region 142 between the infrared transmitter 144 and the infrared receiver 146. Therefore, this arrangement of the infrared transmitter 144 and the infrared receiver 146 can be used to detect the presence of an over-height object within the over-height region 142.

[0058] The over-height detection system 140 further comprises an object detection controller 162 mounted on the holding frame 110 (shown in FIG. 13) configured to control the object detection means. The infrared transmitters 144 and infrared receivers 146 are communicatively coupled to an object detection controller 162 via wires routed along the frame member 112. The object detection controller 162 is configured to switch on and off each infrared transmitter 144. When the infrared receiver 146 detects an infrared signal, a signal is sent from the infrared receiver 146 to the object detection controller 162.

[0059] When the over-height detection system 140 is operating, the object detection controller 162 switches on the first transmitter 144 and waits a period of time to receive a signal from each of the receivers 146 indicating that infrared light from the first transmitter 144 has been detected. If no object is present in the over-height region 142, each infrared receiver 146 should detect the infrared light emitted from the first infrared transmitter 144, and therefore the object detection controller 162 should receive a signal from each receiver 146. The object detection controller 162 then switches off the first transmitter 144, switches on the second transmitter 144, and waits a period of time to receive a signal from each of the receivers 146 indicating that infrared light from the second transmitter 144 has been detected. This process continues until all transmitters 144 have been switched on at least once.

[0060] If, while the over-height detection system 140 is operating, an over-height object is present within the over-height region 142, the optical path between the at least one transmitter 144 and the at least one receiver 146 is blocked by the over-height object 58, and therefore the at least one receiver 146 does not detect a signal from at least one of the transmitters 144. Thus, the object detection controller 162 does not receive signals from all of the receivers 146 when one of the transmitters 144 is switched on. The object detection controller 162 is configured to interpret this as meaning that an object 58 is present in the over-height region 142.

[0061] Depending on the number of transmitters 144 and receivers 146 and the spacing between them, some of the receivers 146 may be too far away to detect infrared radiation emitted from a particular transmitter 144, even if no objects are present in the over-height region. In this case, the object detection controller 162 may be configured to wait to receive signals from a particular number (i.e., one or more) of the receivers 146 after the transmitter 144 is turned on, or from a particular subset of the receivers 146 after a particular transmitter 144 is turned on. For example, if the transmitters 144 and receivers 146 are positioned such that each transmitter 144 is within line-of-sight of only three receivers 146, the object detection controller 162 may be configured to wait to receive signals from three receivers 146 after each transmitter 144 is turned on.

[0062] The number of transmitters 144 and receivers 146 and their placement on the holding frame 110 (e.g., the spacing between transmitters 144 and the spacing between receivers 146) can be selected to reduce the number and size of any blind spots within the excess height region 142.

[0063] The container handling system 100 further comprises a frame controller 164 mounted on the holding frame 110 (shown in FIG. 13 ). The frame controller 164 is communicatively coupled to the object detection controller 162 for actuating the sensor assemblies 143 and receiving feedback from the object detection controller 162 related to the results of object detection. The frame controller 164 is further configured to control the actuators 130 to control the holding assemblies 130, i.e., to open and close the grippers 124, and to receive feedback from the proximity sensors 117.

[0064] The above-described arrangement of infrared transmitters 144 and receivers 146 is one example of how photoelectric sensors arranged in a through-beam configuration can be used to detect the presence of objects within overheight region 142. Photoelectric sensors may also be in a retro-reflective configuration instead of a through-beam configuration. FIG. 15 schematically illustrates an example in which multiple transmitters 144 and receivers 146 are mounted on frame members 112 on one side of frame opening 114. The frame member 112 on the opposite side of frame opening 114 can function as reflector 148, or a separate reflector 148 can be mounted on frame member 112. In this example, sensor assembly 143 operates similarly to the through-beam arrangement described above, except that the signal emitted by transmitter 144 is reflected by reflector 148 before being received by receiver 146. If an object blocks the signal between at least one of the transmitters 144 and the reflector 148, or between the reflector 148 and at least one of the receivers 146, at least one of the receivers 146 will not detect the signal, and the object detection controller 162 can be used to determine that an object is present within the over-height region 142.

[0065] The sensor assembly 143 is not limited to comprising an infrared photoelectric sensor. Other types of photoelectric sensors can be used, such as visible red or laser. The sensor assembly 143 is also not limited to comprising a photoelectric sensor. Other types of object detection sensors known in the art can be used, such as ultrasonic sensors, which can be arranged in a through-beam or retro-reflective configuration, as described above.

[0066] Sensor assembly 143 does not need to be disposed within frame opening 114, and therefore overheight region 142 does not need to be positioned within frame opening 114. Instead, sensor assembly 143 may be mounted above or below frame opening 114 such that overheight region 142 is above or below frame opening 114.

[0067] FIG. 16 is a schematic perspective view of another example of a container handling system 100 in which the object detection means comprises a camera 150 mounted on the holding frame 110 and one or more processors configured to analyze images captured by the camera 150. The one or more processors may be part of the object detection controller 162. When the overheight detection system 140 is operating, the camera 150 is configured to capture at least one image including the overheight region 142, and the one or more processors are configured to analyze the captured image to determine whether an object is present within the overheight region 142. As shown in FIG. 16 , the camera 150 may be mounted to the holding frame 110 at one corner of the frame opening 114 and point generally horizontally toward the opposite corner of the frame opening 114. The viewpoint of the camera 150 may be fixed, and a region of pixels in each image captured by the camera 150 may be designated as the overheight region 142. The captured image may then be analyzed by the processor using known image analysis techniques to determine whether an object is present within the overheight region 142. For example, a machine learning algorithm (e.g., a convolutional neural network) trained to detect the presence of objects in excess height regions may be used. The machine learning algorithm may be trained on images captured by camera 150 that are classified as images that include objects in excess height regions and images that do not include objects in excess height regions.

[0068] The object detection system 140 may further include a light source (e.g., one or more LEDs) mounted on the holding frame 110 to provide light when the camera 150 captures an image, thereby creating greater contrast between the over-height region 142 and objects within the over-height region 142 in the captured image. This may enable the processor to analyze the captured image and more effectively detect objects within the over-height region 142. For example, a white light source may be used so that empty areas of the over-height region appear white in the captured image, and any objects within the over-height region appear dark. The processor may then calculate the ratio of dark pixels to white pixels in the over-height region of the captured image, and if the ratio of dark pixels is above a threshold, the processor determines that an object is present in the over-height region.

[0069] 17 is a schematic bottom perspective view of an alternative support frame 110 that does not have frame openings 114, but instead includes a substantially horizontal sheet 113 mounted between frame members 112. In this example, horizontal sheet 113 covers the top of support frame 110, and frame members 112 extend downwardly from horizontal sheet 113 to define a recess 115 on the bottom side of support frame 110 that provides headroom for overheight objects above the support area. In this illustrated example, overheight detection system 140 is configured to detect the presence of an object in overheight area 142 located within recess 115 using sensor assembly 143 shown in FIG. 13 , i.e., transmitter 144 and receiver 146 mounted on opposite sides of recess 115, although other object detection means, such as sensor assembly 143 shown in FIG. 15 and a camera shown in FIG. 16 , may also be used.

[0070] 17, the holding frame 110 without the transmitter 144 and receiver 146 also represents another example in which the object detection means can comprise a mechanical force sensor. In particular, the force exerted by an over-height object against the underside of the horizontal sheet 113 when the holding frame 110 is being lowered toward the storage container 50 can be used to determine the presence of the over-height object. In this case, the over-height region 142 is defined by the horizontal sheet 113, i.e., the plane on which the horizontal sheet 113 lies or just below the plane on which the horizontal sheet 113 lies. For example, the horizontal sheet 113 can be an elastomeric material under tension, and an increase in tension as measured by a tension sensor can be used to determine the presence of an object in the over-height region 142. Alternatively, the horizontal sheet 113 can be part of a load cell configured to detect a load applied to the horizontal sheet 113. A detected increase in load (e.g., above a certain threshold) can be used to determine the presence of an object in the over-height region 142. 17 illustrates the horizontal sheet 113 as forming the top surface of the holding frame 110, the horizontal sheet 113 may be positioned at other vertical positions relative to the frame members 112. If the holding frame 110 has a frame opening 114, the horizontal sheet 113 may be mounted within the frame opening 114.

[0071] Referring back to FIG. 7 , the container handling system 100 further includes an electrical cable 118 for providing power to various electrical and electronic components on the support frame 110 (e.g., the frame controller 164, the support assembly 120, and the overheight detection system 140). In this illustrated example, one end of the electrical cable 118 is attached to a spool attached to a portion of the lifting assembly 102, such that the electrical cable 118 is wound up and unwound as the lifting assembly 102 reels up and unreels the tether 104. While the other end of the electrical cable 118 is attached to the support frame 110, FIG. 7 shows the electrical cable 118 disconnected from the support frame 110. The electrical cable 118 electrically couples a power source (e.g., a battery) of the bot 25 to the electrical and electronic components mounted on the support frame 110. The electrical cable 118 also enables data transfer (e.g., between the frame controller 164 and the bot controller 166 within or on the body 27 of the bot 25). The electrical cable 118 may be any suitable electrical cable for transmitting power and / or data, for example, a flexible flat cable (FFC).

[0072] The storage and retrieval system may be used to store products that may be ordered by customers. The products are stored in storage containers 50 within the storage structure 1, and the identity and location of each product within the storage structure 1 is stored in a database. The location of a product includes the grid cell 14 under which the storage container 50 containing the product is located and the vertical location of the storage container 50 below the grid cell 14.

[0073] 18 is a block diagram illustrating an exemplary control system for the storage and retrieval system. The locations of the bots 25 on the track structure 13 and their routes between locations on the track structure 13 are controlled by a central control system 170 comprising one or more controllers that wirelessly communicate with each bot 25 on the track structure 13 using wireless transmitters and receivers and suitable wireless communication technologies, such as 4G, 5G, or Wi-Fi. The one or more controllers of the central control system 170 receive data regarding which products are in the storage and retrieval system and which products have been ordered by customers and use this data to calculate routes for the bots 25 between target grid cells 14 to pick up and drop off specific storage containers 50 at specific locations. The one or more controllers of the central control system 170 command the bots 25 to travel to the target grid cells 14 via the calculated routes and pick up or drop off storage containers 50 at the target grid cells 14.

[0074] The bot 25 includes a bot controller 166 configured to control functions of the bot 25, such as operation of the drive assembly to move the bot 25 a specific distance in a specific direction and operation of the lifting assembly 102 to lower and raise the support frame 110. As described above, the bot controller 166 communicates wirelessly with a central control system 170 via a wireless transmitter and receiver attached to the bot 25. The bot controller 166 is configured to receive commands from the central control system 170 (e.g., to move to a specific grid cell 14 via a specific route and pick up or drop off a storage container 50) and to send status updates to the central control system 170 (e.g., to confirm the position of the bot 25 on the track structure 13 and the status of the lifting assembly 102).

[0075] As described above, the support frame 110 includes a frame controller 164 configured to control functions of the support frame 110, including the operation of the support assembly 120. The bot controller 166 and the frame controller 164 are communicatively coupled via an electrical cable 118 such that the bot controller 166 and the frame controller 164 can send signals between each other. For example, the bot controller 166 may instruct the frame controller 164 to activate the support assembly 120, and the frame controller 164 may confirm to the bot controller 166 that the support assembly 120 has been activated.

[0076] Also, as described above, the holding frame 110 further comprises an object detection controller 162 communicatively coupled to the frame controller 164. The object detection controller 162 is configured to control the object detection means, determine the presence of an object within the over-height region 142 from the object detection means, and communicate the results to the frame controller 164.

[0077] During operation of the storage and retrieval system, the central control system 170 may command the bot 25 to follow a calculated route to the target grid cell 14 and pick up a target storage container 50 below the target grid cell 14. The bot controller 166 receives this command and controls the drive assembly to move the bot 25 to the target grid cell 14. The bot controller 166 then controls the lifting assembly 102 to lower the holding frame 110 from its home position (within or above the container receiving space 45) toward the target storage container 50. When the proximity sensor 117 detects that the target storage container 50 is within the holding area, the frame controller 164 sends a signal to the bot controller 166, which controls the lifting assembly 102 to stop lowering the holding frame 110. While the holding frame 110 is being lowered, the frame controller 164 may activate the overheight detection system 140 via the object detection controller 162 to determine whether an object is present within the overheight area 142.

[0078] If, during the descent of the holding frame 110, no object is detected within the excess height region 142, the holding frame 110 reaches the top of the target storage container 50 and the frame controller 164 actuates the holding assembly 120 to engage and hold the storage container 50. The frame controller 164 then communicates to the bot controller 166 that the holding assembly 120 is engaged, and the bot controller 166 controls the lifting assembly 102 to raise the holding assembly 120 back to its home position so that the target storage container 50 is accommodated within the container accommodation space 45 of the bot 25.

[0079] On the other hand, if the object detection controller 162 determines that an object is present in the over-height region 142 during the lowering of the holding frame 110, the frame controller 164 does not activate the holding assembly 120 and communicates the presence of the over-height object to the bot controller 166, which controls the lifting assembly 102 to stop the lowering of the holding frame 110 and return the holding frame 110 to its home position. Once the holding frame 110 returns to the home position, the over-height detection system can be reset so that the frame controller 164 can potentially activate the holding assembly 120 the next time the holding frame 110 is lowered to pick up a storage container 50.

[0080] Alternatively, the overheight detection system 140 may be activated only when the holding frame 110 is lowered to a position above the storage container 50 where the holding assembly 120 can engage the storage container 50 (i.e., when the storage container 50 is in the holding area). If the object detection means detects an object in the overheight area 142, the holding assembly 120 is not activated and the lifting assembly 102 raises the holding frame 110 back to its home position. If the object detection means does not detect an object in the overheight area 142, the holding assembly 120 is activated to engage and hold the storage container 50 and the lifting assembly 102 raises the holding frame 110 back to its home position so that the storage container 50 is accommodated within the container accommodating space 45.

[0081] Thus, the container handling system 100 equipped with the over-height detection system 140 can be used to avoid or minimize the risk of any problems associated with the holding frame 110 attempting to engage with a storage container 50 containing an over-height object, any problems associated with lifting a storage container 50 containing an over-height object into the container receiving space 45 of the bot 25, and any problems associated with the storage container 50 entering other areas of the storage and retrieval system.

[0082] Additionally, the bot controller 166 may send a signal to the central control system 170 indicating that an over-height object was detected while the bot 25 was in the target grid cell 14. In response, the central control system 170 may remove the target grid cell 14 from the list of available grid cells 14 for the storage and retrieval system so that the bot 25 is not instructed to pick up the storage container 50 from that target grid cell 14. The central control system 170 may also trigger a process to address the over-height object. For example, a special type of bot for handling over-height objects may be instructed to move to the target grid cell 14 and retrieve the storage container 50 containing the over-height object. The special bot may have a taller container receiving space 45 that can accommodate the storage container 50 with the over-height object, so that the special bot can pick up the storage container 50 containing the over-height object and deposit it where the over-height object can be removed or relocated within the storage container 50.

[0083] The over-height detection system 140 can also be used to determine the protruding height of an over-height object, i.e., the vertical height of the portion of the over-height object that protrudes above the top of the storage container 50. For example, the vertical distance traveled by the holding frame 110 during an over-height period can be determined, where the over-height period is the time between when the object detection means first detects an object in the over-height region 142 and when the holding frame 110 is in a position to engage the storage container 50 (i.e., when the storage container 50 is within the holding region). The vertical distance traveled by the holding frame 110 during the over-height period approximately corresponds to the protruding height of the over-height object. The vertical distance traveled by the holding frame 110 during the over-height period can be determined in several different ways. For example, the rotation of a lifting assembly component (e.g., a motor, spool, or shaft) that rotates as the tether 104 is unwound can be measured using a rotary encoder, and the measurement from the rotary encoder can be converted to the length of tether 104 unwound from the spool 106 during the over-height period, which corresponds to the vertical distance traveled by the holding frame 110. Alternatively, if the holding frame 110 is lowered (or assumed to be lowered) at a constant or predetermined speed, the vertical distance traveled by the holding frame 110 during the over-height period can be determined using a predetermined value of the speed of the holding frame 110. Determining the protruding height of the over-height object can be performed by one or more of the bot controller 166, the frame controller 164, and the object detection controller 162.

[0084] By determining the protrusion height of the over-height object, the over-height detection system 140 can determine how to proceed based on the over-height object's protrusion height, rather than the mere presence of the over-height object. For example, if the protrusion height is below a protrusion threshold that is unlikely to cause any negative issues, the holding assembly 120 and lifting assembly 102 may operate normally to hold and lift the storage container. In this case, the presence of the over-height object in the storage container 50 need only be logged for reference. However, if the protrusion height is equal to or greater than the protrusion threshold, the holding frame 110 may be raised back into the container receiving space 45 without operating the holding assembly 120, resulting in the storage container 50 not being lifted.

[0085] The invention is not limited to the exact form described above, and various modifications and variations will be apparent to those skilled in the art without departing from the scope of the invention as defined in the appended claims.

[0086] For example, instead of the support frame 110 being formed from four separate elongated frame members 112 joined together, the support frame 110 may be formed from fewer separate frame members 112 (e.g., two L-shaped frame members), or from a single frame member (e.g., a unibody).

[0087] Furthermore, the present invention is not limited to the particular holding assembly 120 described above, and any form of holding assembly 120 for releasably holding a storage container 50 from above may be used. If the holding assembly 120 includes a gripper, the gripper may be movable between an engaged position for engaging the storage container 50 and a disengaged position for disengaging from the storage container 50 using any suitable arrangement of one or more linear or rotary actuators and linkages.

[0088] Furthermore, instead of providing a proximity sensor 117 on the holding frame 110 to detect when the holding frame 110 has been lowered far enough to engage the target storage container 50, the lifting assembly 102 can lower the holding frame 110 a predetermined distance based on the known vertical position of the target storage container 50 within the storage structure 1.

[0089] Furthermore, the above description of the bot controller 166, frame controller 164, and object detection controller 162, and their associated functions, is only one example of how the control system of the bot 25 and the container handling system 100 may be arranged. In the above example, the functions of the container handling system 100 (e.g., operating the lifting assembly 102, operating the support assembly 120, and operating the object detection means) are distributed among the bot controller 166, the frame controller 164, and the object detection controller 162. In other examples, the functions of at least two of the bot controller 166, the frame controller 164, and the object detection controller 162 may be combined. For example, all functions of the container handling system 100 may be performed by a single controller, e.g., the bot controller 166, or the functions of the object detection controller 162 may be incorporated into the frame controller 164. The functions of the container handling system 100 may also be distributed among the bot controller 166, the frame controller 164, and the object detection controller in different ways.

Claims

1. 1. A load handling device for lifting and moving storage containers arranged in a stack within a storage structure, the storage structure comprising a track structure above the stack of storage containers, the load handling device comprising: a) a main body; b) a drive assembly configured to move the body on the track structure; and c) a container handling system, the container handling system comprising: i) a holding frame; ii) a holding assembly attached to the holding frame, wherein the holding assembly is configured to releasably hold a storage container in a holding area relative to the holding frame; iii) a lifting assembly configured to lower and raise the support frame relative to the body; iv) an overheight detection system comprising object detection means attached to said holding frame, wherein said object detection means is configured to detect the presence of an object in an overheight area, wherein said overheight area is above said holding area.

2. 2. The load handling device of claim 1, wherein the excess height area is substantially flat.

3. 3. The load handling device of claim 2, wherein the excess height area is a substantially horizontal plane.

4. 4. A load handling device according to claim 3, wherein the object detection means is configured to detect the presence of an object between at least two points in the horizontal plane.

5. A load handling device according to any one of claims 1 to 4, wherein the excess height area is in a fixed position relative to the holding frame.

6. 6. A load handling device according to any one of claims 1 to 5, wherein the holding assembly is configured to releasably hold a storage container from above.

7. A load handling device according to any preceding claim, wherein the support frame is provided with a frame opening extending vertically through the support frame.

8. 8. The load handling device of claim 7, wherein at least a portion of the excess height region is located within or above the frame opening.

9. A load handling device according to claim 7 or 8, wherein at least part of the object detection means is mounted within or above the frame opening.

10. A load handling device according to any preceding claim, wherein the object detection means comprises sensor assemblies located on opposite sides of the over-height region.

11. The load handling device of claim 10 , wherein the sensor assembly comprises one or more photoelectric sensors.

12. the sensor assembly comprises at least one transmitter and at least one receiver mounted on the support frame on opposite sides of the over-height region, wherein the at least one transmitter is configured to emit a signal toward the at least one receiver, and the at least one receiver is configured to detect the signal from the at least one transmitter; 12. The cargo handling device of claim 10 or 11, wherein the overheight detection system further comprises a controller communicatively coupled to the at least one transmitter and the at least one receiver, wherein the controller is configured to determine that an object is in the overheight region when the signal between the at least one transmitter and the at least one receiver is interrupted.

13. the sensor assembly comprises at least one transmitter and at least one receiver mounted on the support frame on the same side of the over-height region, and at least one reflector on an opposing side of the over-height region, wherein the at least one transmitter is configured to emit a signal toward the at least one reflector, and the at least one receiver is configured to detect the signal from the at least one transmitter after it has been reflected by the at least one reflector; 12. The cargo handling device of claim 10 or 11, wherein the over-height detection system further comprises a controller communicatively coupled to the at least one transmitter and the at least one receiver, wherein the controller is configured to determine that an object is in the over-height region when the signal between the at least one transmitter and the at least one receiver via the at least one reflector is interrupted.

14. The object detection means a camera attached to the holding frame, wherein the camera is configured to capture an image including the excess height region; and one or more processors configured to analyze the images and determine the presence of an object within the excess height region.

15. 10. A load handling device as claimed in any one of claims 1 to 9, wherein the object detection means comprises a substantially horizontal sheet defining the excess height area, the object detection means being configured to detect a force being applied to the horizontal sheet to determine the presence of an object in the excess height area.

16. 16. A load handling device as described in any one of claims 1 to 15, wherein the lifting assembly comprises at least one tether and at least one motor, wherein the at least one tether is coupled between the support frame and the at least one motor, and the at least one motor is configured to reel in and unreel the at least one tether to raise and lower the support frame, respectively.

17. 17. A load handling device according to any preceding claim, further comprising a control system comprising one or more controllers configured to control operation of the retaining assemblies based on detection results by the object detection means.

18. 18. A load handling device according to claim 17, wherein the control system is configured to prevent the retaining assembly from being activated if the object detection means detects the presence of an object in the excess height region.

19. 20. The load handling device of claim 18, wherein the control system is configured to control the lifting assembly to raise the support frame without actuating the support assembly when the object detection means detects the presence of an object in the excess height region.

20. 20. The load handling device of any one of claims 17 to 19, wherein the control system is configured to determine the height of an object protruding above a storage container based on the vertical distance lowered by the holding frame during the period between when the object is first detected in the excess height area and when the storage container is in the holding area.

21. 21. A cargo handling device as described in any one of claims 1 to 20, wherein the holding assembly comprises a plurality of grippers mounted on the holding frame, each gripper being movable between an engagement position for engaging the storage container and a disengagement position for disengaging from the storage container.

22. 22. A cargo handling device as claimed in any one of claims 1 to 21, further comprising a container accommodating space configured to accommodate a storage container held by the holding frame, wherein the lifting assembly is configured to raise and lower the holding frame into and out of the container accommodating space, respectively.

23. 1. A storage and retrieval system comprising: a storage system, the storage system comprising: a stack of storage containers, each storage container having a top opening through which an object can be placed within said storage container; a track structure disposed above the stack of storage containers and configured to allow access to each stack from above; 23. The storage and retrieval system further comprises at least one cargo handling device according to any one of claims 1 to 22, wherein the container handling system is configured to pick up storage containers from the stack of storage containers and drop off storage containers onto the stack of storage containers.

24. 24. The storage and retrieval system of claim 23, wherein the track structure comprises a first set of tracks and a second set of tracks, the first set of tracks extending in a first direction and the second set of tracks extending in a second direction, the second direction being substantially perpendicular to the first direction to form a grid pattern defining a plurality of grid cells, wherein each stack of storage containers is positioned below a grid cell.

25. 25. The storage and retrieval system of claim 24, further comprising a central control system configured to communicate with the at least one load handling device, wherein the central control system is configured to command the load handling device to move to a target grid cell from a list of available grid cells and pick up or drop off a storage container at the target grid cell, wherein the central control system is further configured to remove the target grid cell from the list of available grid cells if the excess height detection system detects an object within the excess height region when the load handling device is at the target grid cell.

26. 23. A method of using a load handling device according to any one of claims 1 to 22, comprising the steps of: lowering the support frame toward a storage container; detecting whether an object is present in the excess height region; if an object is detected, raising the support frame away from the storage container without actuating the support assembly; If no object is detected, actuating the holding assembly to hold the storage container and then raising the holding frame.

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