Method and system for measuring a load-handling device

Abstract

A computer-implemented method of measuring a load-handling device 520 used in an automated storage and retrieval system, ASRS, comprising a grid and one or more robotic manipulators 510 operational

Description

Technical Field The present disclosure relates generally to the field of automated storage and retrieval systems, and in particular measurements of a load handling device used in the automated storage and retrieval system. Background Some commercial and industrial activities require systems that enable the storage and retrieval of a large number of different products. For example, WO2015 / 185628A2 (Ocado) describes an automated storage and fulfilment system (ASRS) in which stacks of storage containers are arranged within a grid storage structure. The containers are accessed from above by load-handling devices operative on rails or tracks located on the top of the grid storage structure. The load-handling devices may be those described in WO2015 / 019055A1 (Ocado). Within the storage and fulfilment system, it is important that the load-handling devices themselves are and remain within certain engineering tolerances. It is against this background that the present invention has been devised. Summary In a first aspect, there is a computer-implemented method of measuring a load-handling device used in an automated storage and retrieval system, ASRS, comprising a grid and one or more robotic manipulators operational on the grid, wherein the load-handling device is configured to move along the grid in transverse directions, the load-handling device comprising a plurality of predefined points, wherein the grid forms part of a gridbased storage system, wherein the robotic manipulator comprises a probe, the method comprising: positioning a load-handling device on the grid adjacent a robotic manipulator; orienting the robotic manipulator for the probe to interact with at least two of the plurality of predefined points; determining whether a measurement between the at least two predefined points is within a predefined tolerance; and outputting a control signal upon determining whether the measurement between the at least two of the plurality of predefined points is within the predefined tolerance. This allows dimensions linked with reliable operation of the load-handling device to be measured, without first having to remove the load-handling device from the ASRS. The method may further comprise upon determining that the measurement between the at least two of the plurality of predefined points is within the predefined tolerance, outputting a control signal to return the load-handling device for operation within the ASRS. The method may further comprise returning the load-handling device for operation within the ASRS. This means that the load-handling device can return for reliable operation within the ASRS. The method may further comprise upon determining that the measurement between the at least two of the plurality of predefined points is not within the predefined tolerance, outputting a control signal to remove the load-handling device from operation within the ASRS. The method may further comprise removing the load-handling device from operation within the ASRS. This means a load-handling device with a defect can be identified and removed from operation within the ASRS. The load-handling device may comprise a generally cuboid shape, wherein the at least two of the plurality of predefined points are at or near respective corners of the generally cuboid shape, and optionally wherein at least three of the plurality of predefined points are at or near respective corners of the generally cuboid shape to measure a squareness of the cuboid shape. This means that a load-handling device that has an increased risk of colliding with another load-handling device whilst moving alongside each other, due to a loss of squareness, can be identified. Each predefined point may comprises an indent to receive the probe. This means a reliable measurement can be taken at the predefined point. The method may further comprise repositioning the load-handling device adjacent the robotic manipulator such that the probe can interact with all of the plurality of predefined points on the load-handling device. This means a single robotic manipulator can measure all of the dimensions of the load-handling device. The ASRS may comprise a plurality of robotic manipulators adjacent the load-handling device, wherein the method of the first aspect is performed using a respective robotic manipulator on a respective side or region of the load-handling device. This means all of the dimensions can be measured in minimal time. Each robotic manipulator may comprise a vision system to enable interaction of the probe with the plurality of predefined points. This means the measurement of the loadhandling device can be visualised and / or automated. Each robotic manipulator may comprise an end effector comprising the probe, wherein the end effector has full mechanical degrees of freedom via orientation of the endeffector and / or via orientation of the robotic manipulator. This means the probe can access all of the predefined points on the load-handling device. The probe may comprises a contact sensor. Each robotic arm may comprise at least one encoder configured to determine the measurement. This means the measurement at a given location can be determined. The grid based storage system may comprises a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane to form the grid comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be stacked between and be guided by the uprights in a vertical direction through the plurality of grid spaces. The load-handling device may comprise: a body or skeleton mounted on a first set of wheels being arranged to engage with the first set of parallel tracks and a second set of wheels being arranged to engage with the second set of parallel tracks; and / or a drive assembly configured to drive the first or second sets of wheels to move the load-handling device along the first or second set of parallel rails in the respective transverse directions; and / or a direction-change assembly configured to raise or lower the first set of wheels and / or lower or raise the second set of wheels with respect to the body or skeleton to engage and disengage the wheels with the parallel tracks; and / or a container-lifting assembly configured to raise or lower a gripping device in the vertical direction to raise or lower a container. At least two of the plurality of predefined points may be on at least one of the body or skeleton, and / or at least one wheel of the first and / or second sets of wheels, and / or the drive assembly, and or the direction-change assembly, and / or the container-lifting assembly, and / or a container accessible below or through the body or skeleton. This means various dimensions linked with reliable operation of respective parts / components on the load-handling device, can be determined. The predefined tolerance may comprise a deviation from a dimension and / or an angle. Outputting the control signal may comprise displaying the at least two of the plurality of predefined points, and / or the measurement between the plurality of predefined points, and / or the predefined tolerance; and / or whether the measurement is within the predefined tolerance. This guides a user through the measurement process. In a second aspect, there is a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of first aspect. In a third aspect, there is a computer readable medium comprising the computer program of the second aspect. In a fourth aspect, there is a data processing system comprising means for carrying out the method of the first aspect. In a fifth aspect, there is an automated storage and retrieval system, ASRS, comprising: a grid; a load-handling device, wherein the load-handling device is configured to move along the grid in transverse directions, the load-handling device comprising a plurality of predefined points; one or more robotic manipulators operational on the grid, wherein the robotic manipulator comprises a probe; and a controller configured to carry out the method of the first aspect. Brief Description of Drawings The invention is described with reference to the accompanying drawings, wherein: Figure 1 shows a known automated storage and retrieval system that uses load-handling devices; Figure 2 shows a known single load-handling device with a container-lifting assembly in a lowered configuration; Figure 3 shows a method for measuring a load-handling device; Figures 4A and 4B show how distances and angles can be measured using the method of Figure 3; Figures 5, 6A, and 6B show a system for measuring a load-handling device; Figures 7A and 7B show a system for measuring a container used within and / or by the load-handling device; Figure 8 shows a load-handling device that can be measured; and Figure 9 shows a system for displaying a measurement of the load-handling device. Detailed Description WO2015 / 185628A (Ocado), hereby incorporated by reference, describes a known ASRS in which stacks of containers are arranged within a grid framework structure. The containers are accessed by one or more load-handling devices, otherwise known as “bots”, operative on tracks located on the top of the grid framework structure. A system of this type is illustrated schematically in Figure 1. As shown in Figures 1, stackable containers 10, also known as “bins” or “totes”, are stacked on top of one another to form stacks 12. The stacks 12 are arranged in a grid framework structure 14. The grid framework structure 14 is made up of a plurality of storage columns or grid columns. Each grid in the grid framework structure has at least one grid column to store a stack of containers. Each bin 10 typically holds a plurality of product items (not shown). The grid framework structure 14 comprises a plurality of upright members 16 that support horizontal members 18, 20. A first set of parallel horizontal grid members 18 is arranged perpendicularly to a second set of parallel horizontal members 20 in a grid pattern comprising respective grid spaces to form a horizontal grid structure 15 supported by the upright members 16. The members 16, 18, 20 are typically manufactured from metal. The bins 10 are stacked between the members 16, 18, 20 of the grid framework structure 14, so that the grid framework structure 14 guards against horizontal movement of the stacks 12 of bins 10 and guides the vertical movement of the bins 10. The top level of the grid framework structure 14 comprises a grid or grid structure 15, including rails 22 arranged in a grid pattern comprising respective grid spaces across the top of the stacks 12. The rails or tracks 22 guide a plurality of load-handling devices 30. A first set 22a of parallel rails 22 guide movement of the robotic load-handling devices 30 in a first direction (e.g. an X-direction along track 22a) across the top of the grid framework structure 14. A second set 22b of parallel rails 22, arranged perpendicular to the first set 22a, guide movement of the load-handling devices 30 in a second direction (e.g. a Y-direction along track 22b), perpendicular to the first direction. In this way, the rails 22 allow the robotic load-handling devices 30 to move laterally in two dimensions in the horizontal X-Y plane. A load-handling device 30 can be moved into position above any of the stacks 12. A known form of load-handling device 30 shown in Figure 2 is described in WO2015 / 019055 (Ocado), hereby incorporated by reference. The load-handling device 30 comprises a vehicle 32, which is arranged to travel on the rails 22 of the frame structure 14. A first set of wheels 34, consisting of a pair of wheels 34 on the front of the vehicle 32 and a pair of wheels 34 on the back of the vehicle 32, is arranged to engage with two adjacent rails of the first set 22a of rails 22. Similarly, a second set of wheels 36, consisting of a pair of wheels 36 on each side of the vehicle 32, is arranged to engage with two adjacent rails of the second set 22b of rails 22. Each set of wheels 34, 36 can be lifted and lowered, by way of a direction-change assembly, so that either the first set of wheels 34 or the second set of wheels 36 is engaged with the respective set of rails 22a, 22b at any one time. For example, when the first set of wheels 34 is engaged with the first set of rails 22a and the second set of wheels 36 is lifted clear from the rails 22, the first set of wheels 34 can be driven, by way of a drive assembly housed in the vehicle 32, to move the load-handling device 30 in the X-direction. To achieve movement in the Y-direction, the first set of wheels 34 is lifted clear of the rails 22, and the second set of wheels 36 is lowered into engagement with the second set 22b of rails 22. The drive assembly can then be used to drive the second set of wheels 36 to move the load-handling device 30 in the Y-direction. The load-handling device 30 is equipped with a container-lifting device or assembly, e.g. a crane mechanism, to lift a storage container from above. The lifting device comprises a winch tether or cable 38 wound on a spool or reel and a gripper device 39. The lifting device shown in Figure 2 comprises a set of four lifting tethers 38 extending in a vertical direction. The tethers 38 are connected at or near the respective four corners of the gripper device 39, e.g. a lifting frame, for releasable connection to a storage container 10. The gripper device 39 is configured to releasably grip the top of a storage container 10 to lift it from a stack of containers in a storage system of the type shown in Figure 1. To remove a bin 10 from the top of a stack 12, the load-handling device 30 is first moved in the X- and Y-directions to position the gripper device 39 in a respective grid space above the stack 12. The gripper device 39 is then lowered vertically in the Z-direction to engage with the container 10 on the top of the stack 12. The gripper device 39 grips the container 10, and is then pulled upwards by the cables 38, with the container 10 attached. At the top of its vertical travel, the container 10 is held above the rails 22 accommodated within the vehicle body (or skeleton) 32. In this way, the load-handling device 30 can be moved to a different position in the X-Y plane, carrying the container 10 along with it, to transport the container 10 to another location. On reaching the target location (e.g. another stack 12, an access point in the storage system, or a conveyor belt) the container 10 can be lowered from the container receiving portion and released from the gripper device 39. It will be appreciated that the ASRS and the load-handling devices are under the control of a master controller. Each load-handling device and container used in the ASRS has a defined set of engineering dimensions and tolerances. Operating within these dimensions and tolerances ensures that the ASRS runs smoothly. For example, a footprint and / or general dimensions of a load-handling device should be of a size that ensures contact with another load-handling device does not happen when moving alongside. Similarly, a container should have dimensions to allow interference free gripping, and / or raising, and / or lowering by the container-lifting assembly. Of course, the required engineering dimensions and tolerances are verified before a load-handling device and / or container is added to the ASRS. Over time, wear will occur due to repeated use of the load-handling device and / or container. The wear could mean that the required engineering tolerances are no longer present and smooth operation of the ASRS is at risk. For example, a loadhandling device may collide with another load-handling device, and / or a container may no longer be freely gripped, and / or raised, and / or lowered by the load-handling device. It is important to verify the engineering dimensions and tolerances of the load-handling device and / or container as part of a regular maintenance cycle. The set of engineering dimensions and tolerances for the load-handling device and / or container can involve a significant number of measurements. Therefore, it would be advantageous to do this without first having to remove the load-handling device and / or container from the ASRS. With reference to Figure 3, a method according to the invention is described. The method is used to measure a load-handling device in an automated storage and retrieval system, ASRS, having a grid forming part of a grid-based storage system. One or more robotic manipulators are operational on the grid, where each robotic manipulator has a probe. The load-handling device has a plurality of predefined points, and is configured to move along the grid in transverse directions. The system may therefore include the system described above in Figures 1 and 2 and one or more robotic manipulators. In step 310, a load-handling device is positioned on the grid adjacent a robotic manipulator. Both the load-handling device and the robotic manipulator may be under the control of the master controller. In one example, the robotic manipulator may be operational at a given location on the grid and the load-handling device is instructed by the master controller to move along the tracks to the given location. In an alternative or additional example, the robotic manipulator may be movable along the grid itself by using similar drive and direction-change assemblies to the load-handling device, or an overhead suspended rail system, to allow positioning adjacent the load-handling device when instructed by the master controller. In step 320, the robotic manipulator is oriented for the probe to interact with at least two of a plurality of predefined points. In one example, the at least two predefined points correspond to an engineering measurement of interest on the load-handling device, such as a height, width, or length of the load-handling device. In another example, the at least two predefined points correspond to a container held by the load-handling device. At each of the at least two predefined points, the robotic manipulator can provide absolute XYZ coordinates for a respective point, and / or relative XYZ coordinates for a respective point. The coordinates may be obtained from an encoder or encoders of the robotic manipulator. In general, the coordinates allow geometric dimensions to be determined. The type of coordinate system used does not matter provided respective points can be compared to determine a measurement. Accordingly, in step 330, it is determined whether a measurement between the at least two of the plurality of predefined points is within a predefined tolerance. In one example, the method compares the measurement between the at least two of the plurality of predefined points to respective dimensions and / or angles, and / or tolerances stored in a database. The comparison may involve determining whether a distance and / or angle between the at least two of the plurality predefined points is within a tolerance stored in a database. In one example, it is determined whether the measurement is within permissible minimum and maximum dimensions and / or angles. Based on the determining in step 330, in step 340, a control signal is output. In one example, the control signal may be used to indicate that the measurement between the at least two of the plurality of predefined points is within the predefined tolerance. In another example, the control signal may be used to indicate that the measurement between the at least two of the plurality of predefined points is not within the predefined tolerance. In either case, the indication may appear on a display device that is in communication with the master controller. In another example, the control signal may cause the load-handling device to return to normal operation within the ASRS when the measurement between the at least two of the plurality of predefined points is within the predefined tolerance. Alternatively, when the measurement between the at least two of the plurality of predefined points is not within the predefined tolerance, the control signal may cause the load-handling device to be removed from the ASRS, and move towards a maintenance area for example. It will be appreciated that the above method may be iterated to perform a set of measurements on the load-handling device and the control signal updated after each iteration. The return and / or removal of the load-handling device to and / or from the ASRS may only be instructed when the set of measurements has been completed. Similarly, the load-handling device may be instructed to return and / or remove the container from further use in the ASRS. The above method may involve repositioning the load-handling device so that each of the plurality of predefined points may be accessed by the probe. In one example, the probe may be able to access a subset of the plurality of predefined points, wherein the subset is located on one side of the generally cuboid shaped load-handling device. In such a case, the load handling device can re-position relative to the robotic manipulator to present another subset of the plurality of points (e.g. another side of the generally cuboid shaped load-handling device). This process may be repeated until each of the plurality of predefined points has been accessed by the probe. The same process can be applied in respect of the container either alone or in combination with the load-handling device itself. Additionally or alternatively, the above method may involve at least two robotic manipulators. Each of the robotic manipulators may access a subset of the plurality of predefined points of the load-handling device to collectively access all of the plurality of predefined points. This can speed up the time taken to complete the set of measurements. The same process can be applied in respect of the container either alone or in combination with the load-handling device itself. As apparent from Figures 1 and 2 above, the load-handling device has a generally cuboid shape. Therefore, the method of Figure 3 can be used to determine the squareness of the cuboid by having the probe interact with predefined points at respective corners. In one example, any two edges defining the corners should have a 90° ±x° (where x is a predefined tolerance) angle between them, which can be verified using the method of Figure 3. Figure 4A shows one example of how interacting with at least two of the predefined points can be used in the method of Figure 3. In Figure 4A, two predefined points 410a and 430a correspond to those with which the probe interacts. These points are compared to respective predefined dimensions and tolerances. In this example, it can then be deduced that whilst the horizontal displacement between points 410a and 430a is within an acceptable predefined tolerance, point 430a is vertically displaced 440a from where it should be, as represented by point 420a. That is, point 410a and points 420a have a vertical displacement that exceeds a predefined tolerance. Accordingly, this measurement can be determined not to be within a predefined tolerance. It will be appreciated that the measurement can also involve the displacement in a direction perpendicular to both the horizontal (e.g. the X-direction) and vertical (e.g. the Y-direction) displacements shown in Figure 4A (e.g. the Z direction). When a vertical displacement is present, an angle 450a can also be determined. The angle 450a may be used to define the predefined tolerance. Figure 4B shows another example of how interacting with at least two of the predefined points can be used in the method of Figure 3. In Figure 4B, three predefined points 410b, 420b, and 430b correspond to those with which the probe interacts. These points are compared to respective predefined dimensions and tolerances. Even if it is found the geometric dimensions between each of the points are within respective tolerances, a determination of the angle 440b can be made to ensure the angle is within a predefined tolerance. Whilst this example is shown as a right angle or 90°, in principle any angle can be measured and compared with a predefined tolerance. A system that can be used to carry out the method of Figure 3 is shown in Figure 5. The system 500 shows a portion of an ASRS, similar to that in Figure 1, with tracks 505 (e.g. tracks 22a,b). A robotic manipulator comprising a robotic arm 510 is mounted to the grid, although as explained above, the robotic manipulator may itself be moveable along the grid or above it. The robotic arm comprises an end effector 540 comprising a probe (an example of which is shown in Figure 5B). In general, the robotic arm has a number of joints (i.e. points of articulation) 506a-c to enable full mechanical degrees of freedom. That is, the end effector can ‘point’ in any direction along the XYZ axes in Figure 5, and rotate in pitch, roll, and yaw along an axis of the XYZ axes. Whilst this example shows 3 joints, it will be appreciated more or fewer joints may be used. For simplicity, a load-handling device is shown as a shell 520. In use, a load-handling device would be positioned similarly to the shell. The shell (or load-handling device) comprises a number of predefined points 530 that the end effector interacts with via the probe. The predefined points are positioned on the shell (or load-handling device) that allow measurements of interest to be determined. Figure 6B shows one example of how the probe may interact with a predefined point. Figure 6B corresponds to the section 620 of system 600 shown in Figure 6A. System 600 is similar or the same to that shown in Figure 5. The predefined points comprise an assembly 630 mounted or attached to the load-handling device. The assembly 630 in this example comprises a hemispherical indent or recess to receive a spherical probe 650. In general, the shape used by the indent or recess and probe is not critical provided they can reliably interact with one another. The mount optionally comprises an identifying mark 640. If the identifying mark corresponds to a location on the load-handling device, this can assist with the placement of the mount during manufacture of the load-handling device. The probe is releasably connected to the end effector via member 660, which may be a screw thread attachment or a bolt attachment. The probe in this example is a contact probe (one suitable probe is a metrology probe such as the “M3-stylus” manufactured by Hexagon ABRTM), but in principle other types of probes such as a laser or optical probe. This is an example only to illustrate the general principle that provided the probe can interact with a predefined point, the method of Figure 3 can be performed accurately. Figure 7B shows an example of how the probe 760 may interact with a predefined point 750 on a container 730. Figure 7B corresponds to the section 740 of system 700 shown in Figure 7A. System 700 is similar or the same to that shown in Figure 5. In this example, the container is suspended below the top of the grid to allow the probe to interact with the predetermined points. The predefined points may be the same or similar to that shown in Figure 6B, but in general all is required that the probe can interact with a predefined point on the container. In the systems of Figures 5, 6A, 6B, 7A, and 7B, the robotic arm and / or end effector may comprise a vision system (not shown) to assist the probe locate the predefined points. Further, the robotic arm may comprise one or more encoders to determine the position of the probe in absolute and / or relative terms. Once the probe interacts with a predefined point, the position of the probe at that time can be determined using the encoders. One such robotic arm that may be used is UR10 by Universal RobotsR™. Figure 8 shows a load-handling device 800 further described in PCT / EP2022 / 051652, herby incorporated by reference. In practice, predefined points may be anywhere on the load-handling device 800 or a container (not shown). For example, 4 corner points 810 may be used collectively to determine the squareness of the top of the load-handling device with respect to predefined tolerances. In another example, the wheels 830 may be measured to determine whether diameter and / or thickness are within predefined tolerances. Similarly, components of the load-handling device, such as the drive assembly, and / or direction-change assembly, and / or the container-lifting assembly may be measured. Accordingly, gaps 840 in the load-handling device may be accessed for any such measurements. The gaps 840 may also be used for the probe to interact with a container held by the container-lifting assembly. Figure 9 shows a system 900 to provide visual feedback when carrying out the method of Figure 3. A controller 920, which may be the master controller, has a robotic manipulator interface 910. The robotic manipulator interface is used to control and transfer data / commands to and from the robotic manipulator. This allows the controller to move the probe towards a given predefined point and receive coordinate data (e.g. via encoders of the robotic manipulator) upon interaction with the given predefined point. The controller interacts with a vision system that provides a display of the load-handling device, and also assists with the interaction of the probe. Accordingly, the vision system may use an object detection model that recognises the predefined points, and control the robotic arm to interact with the predefined points in a given order. The controller also interacts with a measurements and tolerances database 925 to make a determination and output in accordance with steps 330 and 340 of Figure 3. The controller also has a display interface 930 to display images and data on display 960. In one example, the vision system obtains a wide view image of the load-handling device shown in Figure 8, and overlays predefined points Pi, P2, and P3 950 for the current measurement. The positioning and angle date for the points Pi, P2, and P3 is shown in display element 960. This positioning data is compared with predefined tolerances obtained from the measurements and tolerances database. In this example, it is determined that the measurements are within the predefined tolerances so the control signal generates display element 970. It will be appreciated that a different element would be displayed if the measurements were not within the predefined tolerances. In this document, “controller” is intended to include any hardware which is suitable for controlling (e.g. providing instructions to) one or more other components. For example, a processor equipped with one or more memories and appropriate software to process data relating to a component or components and send appropriate instructions to the component(s) to enable the component(s) to perform its / their intended function(s). Furthermore, the invention can take the form of a computer program embodied as a computer-readable medium having computer executable code for use by or in connection with a computer. Reference to an element in the singular is not intended to mean only one unless specifically so stated, but rather “one or more.” The subsequent use of a definite article (e.g., “the” or “said”) with an element (e.g., “the processor”) is not intended to invoke a singular meaning (e.g., “only one”) on the element unless otherwise specifically stated. For example, reference to an element (e.g., “a processor,” “a controller,” “a memory,” “a transceiver,” “an antenna,” “the processor,” “the controller,” “the memory,” “the transceiver,” “the antenna,” etc.), unless otherwise specifically stated, should be understood to refer to one or more elements (e.g., “one or more processors,” “one or more controllers,” “one or more memories,” “one more transceivers,” etc.). The terms “set” and “group” are intended to include one or more elements, and may be used interchangeably with “one or more.” Where reference is made to one or more elements performing functions (e.g., steps of a method), one element may perform all functions, or more than one element may collectively perform the functions. When more than one element collectively performs the functions, each function need not be performed by each of those elements (e.g., different functions may be performed by different elements) and / or each function need not be performed in whole by only one element (e.g., different elements may perform different sub-functions of a function). Similarly, where reference is made to one or more elements configured to cause another element (e.g., an apparatus) to perform functions, one element may be configured to cause the other element to perform all functions, or more than one element may collectively be configured to cause the other element to perform the functions. It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this invention.

Claims

1. A computer-implemented method of measuring a load-handling device used in an automated storage and retrieval system, ASRS, comprising a grid and one or more robotic manipulators operational on the grid, wherein the load-handling device is configured to move along the grid in transverse directions, the load-handling device comprising a plurality of predefined points, wherein the grid forms part of a grid-based storage system, wherein the robotic manipulator comprises a probe, the method comprising:positioning a load-handling device on the grid adjacent a robotic manipulator;orienting the robotic manipulator for the probe to interact with at least two of the plurality of predefined points;determining whether a measurement between the at least two predefined points is within a predefined tolerance; andoutputting a control signal upon determining whether the measurement between the at least two of the plurality of predefined points is within the predefined tolerance.

2. The computer-implemented method of claim 1, wherein the method further comprises upon determining that the measurement between the at least two of the plurality of predefined points is within the predefined tolerance, outputting a control signal to return the load-handling device for operation within the ASRS.

3. The computer-implemented method of claim 2, wherein the method further comprises returning the load-handling device for operation within the ASRS.

4. The computer-implemented method of claims 1-3, wherein the method further comprises upon determining that the measurement between the at least two of the plurality of predefined points is not within the predefined tolerance, outputting a control signal to remove the load-handling device from operation within the ASRS.

5. The computer-implemented method of claim 4, wherein the method further comprises removing the load-handling device from operation within the ASRS.

6. The computer-implemented method of claims 1-5, wherein the load-handling device comprises a generally cuboid shape, wherein the at least two of the plurality ofpredefined points are at or near respective corners of the generally cuboid shape, and optionally wherein at least three of the plurality of predefined points are at or near respective corners of the generally cuboid shape to measure a squareness of the cuboid shape.

7. The computer-implemented method of claims 1-6, wherein each predefined point comprises an indent to receive the probe.

8. The computer-implemented method of claims 1-7, wherein the method further comprises repositioning the load-handling device adjacent the robotic manipulator such that the probe can interact with all of the plurality of predefined points on the loadhandling device.

9. The computer-implemented method of claims 1-7, wherein the ASRS comprises a plurality of robotic manipulators adjacent the load-handling device, wherein the method of claim 1 is performed using a respective robotic manipulator on a respective side or region of the load-handling device.

10. The computer-implemented method of claims 1-9, wherein each robotic manipulator comprises a vision system to enable interaction of the probe with the plurality of predefined points.

11. The computer-implemented method of claims 1-10, wherein each robotic manipulator comprises an end effector comprising the probe, wherein the end effector has full mechanical degrees of freedom via orientation of the end-effector and / or via orientation of the robotic manipulator.

12. The computer-implemented method of claims 1-11, wherein the probe comprises a contact sensor.

13. The computer-implemented method of claims 1-12, wherein each robotic arm comprises at least one encoder configured to determine the measurement.

14. The computer-implemented method of claims 1-13, wherein the grid based storage systems comprises a first set of parallel rails or tracks and a second set ofparallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane to form the grid comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be stacked between and be guided by the uprights in a vertical direction through the plurality of grid spaces.

15. The computer-implemented method of claim 14, wherein the load-handling device comprises:a body or skeleton mounted on a first set of wheels being arranged to engage with the first set of parallel tracks and a second set of wheels being arranged to engage with the second set of parallel tracks; and / ora drive assembly configured to drive the first or second sets of wheels to move the load-handling device along the first or second set of parallel rails in the respective transverse directions; and / ora direction-change assembly configured to raise or lower the first set of wheels and / or lower or raise the second set of wheels with respect to the body or skeleton to engage and disengage the wheels with the parallel tracks; and / ora container-lifting assembly configured to raise or lower a gripping device in the vertical direction to raise or lower a container.

16. The computer-implemented method of claim 15, wherein the at least two of the plurality of predefined points are on at least one of the body or skeleton, and / or at least one wheel of the first and / or second sets of wheels, and / or the drive assembly, and or the direction-change assembly, and / or the container-lifting assembly, and / or a container accessible below or through the body or skeleton.

17. The computer-implemented method of claims 1-16, wherein the predefined tolerance comprises a deviation from a dimension and / or an angle.

18. The computer-implemented method of claims 1-17, wherein outputting the control signal comprises displaying the at least two of the plurality of predefined points, and / or the measurement between the plurality of predefined points, and / or the predefined tolerance; and / or whether the measurement is within the predefined tolerance.

19. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any preceding claim.

20. A computer readable medium comprising the computer program of claim 19.

21. A data processing system comprising means for carrying out the method ofclaims 1-18.

22. An automated storage and retrieval system, ASRS, comprising: a grid;a load-handling device, wherein the load-handling device is configured to move along the grid in transverse directions, the load-handling device comprising a plurality of predefined points;one or more robotic manipulators operational on the grid, wherein the robotic manipulator comprises a probe; anda controller configured to carry out the method of claims 1-18.

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