WO2023170179A1

WO2023170179A1 - Communications system

Info

Publication number: WO2023170179A1
Application number: PCT/EP2023/055940
Authority: WO
Inventors: Yu AN; Amy Paula STEPHENS; Nick MARLEY; Mohsin SHEIKH; Parth AMIN
Original assignee: Ocado Innovation Limited
Priority date: 2022-03-08
Filing date: 2023-03-08
Publication date: 2023-09-14
Also published as: GB2619129A; GB202303395D0; GB202203211D0

Abstract

A a multiframe communications system for use with a plurality of load handling devices in an automated storage and retrieval system. Each frame of the multiframe comprises a uplink subframe and a downlink subframe. Each of load handling devices has an allocated downlink and uplink subframes an a time offset is applied such that the uplink is transmitted in a different frame to the associated downlink. The offset may be equivalent to one or more frames.

Description

COMMUNICATIONS SYSTEM

The invention relates to a communications system, and in particular to a communications system for use with robots in a warehouse facility.

BACKGROUND

Grid-based automatic storage and retrieval systems are well known in the art. In such systems a plurality of robotic load handlers operate on a horizontal grid structure, underneath which is received a plurality of containers, arranged in a plurality of stacks. The containers are used to hold products and the load handlers are adapted to retrieve containers from one of the plurality of stacks and to deposit a container within one of the stacks. The load handlers may be routed in an autonomous manner (or a semi- autonomous manner) on the grid but a wireless communications system is required to transmit instructions to load handlers and to enable each of the load handlers to communicate with a management system. The claimed apparatus, methods, systems and computer programs are intended to provide improvements relating to communications systems for use in an automated retrieval and storage system which uses a fleet of robotic load handlers.

SUMMARY

According to a first aspect of the present disclosure, there is provided a communication system for a warehouse facility with robots, the communication system comprising: one or more base stations; a plurality of robots configured to move around a grid within the warehouse facility and perform operations, wherein the base stations and the robots comprise means for transmitting and receiving data over communication links; and a communication manager that is configured to define and manage said communication links; wherein the communication links comprise a plurality of low bandwidth communication links configured for communication between the one or more base stations and the robots, and one or more high bandwidth communication links configured for communication between the one or more base stations and one or more of the robots, wherein: each of the communications links comprises a plurality of multiframes; each of the plurality of multiframes comprises a plurality of frames; and each of the frames comprises a downlink subframe and an uplink subframe wherein each of the frames are configured such that the uplink subframe is offset from the associated downlink subframe by one or more frames.

Each robot may be allocated a respective low bandwidth communication link number when the robot is first introduced to the system, the low bandwidth communication link number being stored on the robot, such that each robot has for use a dedicated low bandwidth communication link of the plurality of low bandwidth communication links. The low bandwidth communication link number may be associated with one of the frames such that a base station communicates with a robot in the downlink subframe of that frame. The robot may respond to the base station in the uplink subframe of a subsequent offset frame.

By modifying the frame structure such that the uplink subframe is offset from the associated downlink subframe, it is possible to match the requirements of the communications system with that of the robots which use the communications system. A robot which can respond to a received message in the offset uplink subframe, which may be present in the subsequent frame to the downlink subframe in which the message was received. This temporal offset greatly increases the possibility that the robot is able to respond to the received message in the offset uplink subframe. If the associated downlink and uplink subframes are in the same frame then there is an increased chance that the robot is not able to respond in the associated uplink subframe.

In such an event, the robot has to wait for its allocated uplink subframe in the subsequent multiframe, incurring a much greater delay. By offsetting the uplink subframe in time relative to the associated downlink subframe it is possible to obtain more predictable network performance in terms of the round trip time for system-robot communications, leading to increased system performance.

According to a second aspect of the present disclosure, there is provided a storage system comprising: a first set of parallel tracks extending in an X-direction, and a second set of parallel tracks extending in a Y-direction transverse to the first set in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces; a plurality of stacks of storage containers located beneath the tracks, and arranged such that each stack is located within a footprint of a single grid space; at least one transporting device, the at least one transporting device being arranged to selectively move in the X and/or Y directions, above the stacks on the tracks and arranged to transport a storage container; a picking station arranged to receive a storage container transported by the at least one transporting device and to transfer an item from the storage container into a delivery container; and a communication system as described above. The at least one transporting device may have a footprint that occupies only a single grid space in the storage system, such that a transporting device occupying one grid space does not obstruct a transporting device occupying or traversing the adjacent grid spaces in the X and/or Y directions.

BRIEF DESCRIPTION OF THE DRAWINGS

The communication system will now be described in detail with reference to examples, in which:

Figure 1 schematically illustrates a storage structure and containers;

Figure 2 schematically illustrates track on top of the storage structure illustrated in Figure 1 ;

Figure 3 schematically illustrates load-handling devices on top of the storage structure illustrated in Figure 1 ;

Figure 4 schematically illustrates a single load-handling device with containerlifting means in a lowered configuration;

Figure 5 schematically illustrates cutaway views of a single load-handling device with container-lifting means in a raised and a lowered configuration;

Figure 6 shows a schematic depiction of a communications system which enables a plurality of bots to communicate with a central computing device;

Figure 7 shows a first example of the structure of the frames that are used in the communications system; Figure 8 shows a schematic depiction of the structure of a subframe that is used in the communications system;

Figure 9 shows a schematic depiction of an alternative multiframe arrangement in which an offset between a downlink subframe and the associated uplink subframe is applied; and

Figure 10 shows a schematic depiction of a computer device used in the implementation of a communications system.

DETAILED DESCRIPTION

The following embodiments represent the applicant’s preferred examples of how to implement a communications system for use with robots in a warehouse but they are not necessarily the only examples of how that could be achieved.

Figure 1 illustrates a storage structure 1 comprising upright members 3 and horizontal members 5, 7 which are supported by the upright members 3. The horizontal members 5 extend parallel to one another and the illustrated x-axis. The horizontal members 7 extend parallel to one another and the illustrated y-axis, and transversely to the horizontal members 5. The upright members 3 extend parallel to one another and the illustrated z-axis, and transversely to the horizontal members 5, 7. The horizontal members 5, 7 form a grid pattern defining a plurality of grid cells. In the illustrated example, containers 9 are arranged in stacks 11 beneath the grid cells defined by the grid pattern, one stack 11 of containers 9 per grid cell.

Figure 2 shows a large-scale plan view of a section of track structure 13 forming part of the storage structure 1 illustrated in Figure 1 and located on top of the horizontal members 5, 7 of the storage structure 1 illustrated in Figure 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 mounted on 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 which extend in the x-direction and a second set of tracks 19 which extend in the y- direction, transverse to the tracks 17 in the first set of tracks 17. The tracks 17, 19 define apertures 15 at the centres of the grid cells. The apertures 15 are sized to allow containers 9 located beneath the grid cells to be lifted and lowered through the apertures 15. The x-direction tracks 17 are provided in pairs separated by channels 21 , and the /-direction tracks 19 are provided in pairs separated by channels 23. Other arrangements of track structure may also be possible.

Figure 3 shows a plurality of load-handling devices 31 moving on top of the storage structure 1 illustrated in Figure 1. The load-handling devices 31 , which may also be referred to as robots 31 or bots 31 , are provided with sets of wheels to engage with corresponding x- or /-direction tracks 17, 19 to enable the bots 31 to travel across the track structure 13 and reach specific grid cells. The illustrated pairs of tracks 17, 19 separated by channels 21 , 23 allow bots 31 to occupy (or pass one another on) neighbouring grid cells without colliding with one another.

As illustrated in detail in Figure 4, a bot 31 comprises a body 33 in or on which are mounted one or more components which enable the bot 31 to perform its intended functions. These functions may include moving across the storage structure 1 on the track structure 13 and raising or lowering containers 9 (e.g. from or to stacks 11 ) so that the bot 31 can retrieve or deposit containers 9 in specific locations defined by the grid pattern.

The illustrated bot 31 comprises first and second sets of wheels 35, 37 which are mounted on the body 33 of the bot 31 and enable the bot 31 to move in the x- and y- directions along the tracks 17 and 19, respectively. In particular, two wheels 35 are provided on the shorter side of the bot 31 visible in Figure 4, and a further two wheels 35 are provided on the opposite shorter side of the bot 31 (side and further two wheels 35 not visible in Figure 4). The wheels 35 engage with tracks 17 and are rotatably mounted on the body 33 of the bot 31 to allow the bot 31 to move along the tracks 17. Analogously, two wheels 37 are provided on the longer side of the bot 31 visible in Figure 4, and a further two wheels 37 are provided on the opposite longer side of the bot 31 (side and further two wheels 37 not visible in Figure 4). The wheels 37 engage with tracks 19 and are rotatably mounted on the body 33 of the bot 31 to allow the bot 31 to move along the tracks 19. The bot 31 also comprises container-lifting means 39 configured to raise and lower containers 9. The illustrated container-lifting means 39 comprises four tapes or reels 41 which are connected at their lower ends to a container-engaging assembly 43. The container-engaging assembly 43 comprises engaging means (which may, for example, be provided at the comers of the assembly 43, in the vicinity of the tapes 41 ) configured to engage with features of the containers 9. For instance, the containers 9 may be provided with one or more apertures in their upper sides with which the engaging means can engage. Alternatively or additionally, the engaging means may be configured to hook under the rims or lips of the containers 9, and/or to clamp or grasp the containers 9. The tapes 41 may be wound up or down to raise or lower the container-engaging assembly, as required. One or more motors or other means may be provided to effect or control the winding up or down of the tapes 41 .

As can be seen in Figure 5, the body 33 of the illustrated bot 31 has an upper portion 45 and a lower portion 47. The upper portion 45 is configured to house one or more operation components (not shown). The lower portion 47 is arranged beneath the upper portion 45. The lower portion 47 comprises a container-receiving space or cavity for accommodating at least part of a container 9 that has been raised by the container-lifting means 39. The container-receiving space is sized such that enough of a container 9 can fit inside the cavity to enable the bot 31 to move across the track structure 13 on top of storage structure 1 without the underside of the container 9 catching on the track structure 13 or another part of the storage structure 1 . When the bot 31 has reached its intended destination, the container-lifting means 39 controls the tapes 41 to lower the container-gripping assembly 43 and the corresponding container 9 out of the cavity in the lower portion 47 and into the intended position. The intended position may be a stack 11 of containers 9 or an egress point of the storage structure 1 (or an ingress point of the storage structure 1 if the bot 31 has moved to collect a container 9 for storage in the storage structure 1 ). Although in the illustrated example the upper and lower portions 45, 47 are separated by a physical divider, the upper and lower portions 45, 47 may not be physically divided by a specific component or part of the body 33 of the bot 31 . To enable the bot 31 to move on the different wheels 35, 37 in the first and second directions, the bot 31 includes a wheel-positioning mechanism for selectively engaging either the first set of wheels 35 with the first set of tracks 17 or the second set of wheels 37 with the second set of tracks 19. The wheel-positioning mechanism is configured to raise and lower the first set of wheels 35 and/or the second set of wheels 37 relative to the body 33, thereby enabling the load-handling device 31 to selectively move in either the first direction or the second direction across the tracks 17, 19 of the storage structure 1 .

The wheel-positioning mechanism may include one or more linear actuators, rotary components or other means for raising and lowering at least one set of wheels 35, 37 relative to the body 33 of the bot 31 to bring the at least one set of wheels 35, 37 out of and into contact with the tracks 17, 19. In some examples, only one set of wheels is configured to be raised and lowered, and the act of lowering the one set of wheels may effectively lift the other set of wheels clear of the corresponding tracks while the act of raising the one set of wheels may effectively lower the other set of wheels into contact with the corresponding tracks. In other examples, both sets of wheels may be raised and lowered, advantageously meaning that the body 33 of the bot 31 stays substantially at the same height and therefore the weight of the body 33 and the components mounted thereon does not need to be lifted and lowered by the wheelpositioning mechanism.

To remove a container 9 from the top of a stack 11 , the bot 31 is moved as necessary in the X and Y directions so that the container-gripping assembly 43 is positioned above the stack 11 . The container-gripping assembly 43 is then lowered vertically in the Z direction to engage with the container 9 on the top of the stack 11 . The containergripping assembly 43 grips the container 9, and is then pulled upwards on the tapes 41 , with the container 9 attached. At the top of its vertical travel, the container 9 is accommodated within the vehicle body and is held above the level of the tracks. In this way, the load handling device 30 can be moved to a different position in the X-Y plane, carrying the container 9 along with it, to transport the container 9 to another location. The tapes 41 are long enough to allow the load handling device 30 to retrieve and place containers from any level of a stack 11 , including the floor level. The weight of the vehicle may be comprised in part of batteries that are used to power the drive mechanism for the wheels 35, 37.

As shown in Figure 3, a plurality of load handling devices 31 are provided, so that each bot 31 can operate simultaneously to increase the throughput of the system. The system illustrated in Figure 3 may include specific locations, known as ports, at which containers 9 can be transferred into or out of the system. An additional conveyor system (not shown) is associated with each port, so that containers 9 transported to a port by a bot 31 can be transferred to another location by the conveyor system, for example to a picking station (not shown). Similarly, containers 9 can be moved by the conveyor system to a port from an external location, for example to a container-filling station (not shown), and transported to a stack 11 by the bots 31 to replenish the stock in the system.

Each bot 31 can lift and move one container 9 at a time. If it is necessary to retrieve a container (“target container”) that is not located on the top of a stack 11 , then the overlying containers (“non-target containers”) must first be moved to allow access to the target container. This is achieved in an operation referred to hereafter as “digging”. During a digging operation, one of the bots 31 sequentially lifts each non-target container 9a from the stack 11 containing the target container 9b and places it in a vacant position within another stack 11 . The target container 9b can then be accessed by the bot 31 and moved to a port for further transportation.

Each of the bots 31 is under the control of a grid controller. Each individual container 9 in the system is tracked, so that the appropriate containers 9 can be retrieved, transported and replaced as necessary. For example, during a digging operation, the locations of each of the non-target containers is logged, so that the non-target containers can be tracked.

The system described with reference to Figures 1 to 5 has many advantages and is suitable for a wide range of storage and retrieval operations. In particular, it allows very dense storage of product, and it provides a very economical way of storing a huge range of different items in the containers 9, while allowing reasonably economical access to all of the containers 9 when required for picking.

It should be understood that it is necessary for messages to be transmitted to the bots. These may be short messages, for example an instruction to move a container from a first location to a second location, or the messages may be larger, for example an update to the computer code which is used to operate the bot or a component of the bot. Similarly, it may be necessary for the bot to send messages to a central management system, for example to report operating parameter values, operating state reports etc. An example of a communications system which can be used is disclosed in the Applicant’s international patent application WO 2015/185726.

Figure 6 shows a schematic depiction of a communications system 100 which enables a plurality of bots 31 to communicate with a central computing device 400. The computing device executes a number of different computer programs such that it is able to transmit instructions to each of the plurality of bots and to receive messages back from each of the plurality of bots. The messages sent from the computing device to a bot may instruct the bot to: move to a specific grid location; deposit the container it is carrying at its present location; retrieve the top-most container from its current location; move to a charging point for battery charging; etc. The messages returned by a bot to the computing device may comprise: an acknowledgement that a message from the computing device has been received and is being actioned; a request that the bot moves to a charging point for battery charging; a request that the bot returns for maintenance activity etc. The computing device controls the operation of the storage and retrieval system such that, amongst other things, products received are stored for subsequent retrieval; stored products are retrieved such that customer orders can be picked, packed and despatched in a timely manner; the products stored within the storage and retrieval system are arranged & re-arranged to support the efficient operation of the system.

The communications system 100 comprises base stations 200A and 200B. Each of the bots 31 comprises a radio antenna such that it can communicate with one of the base stations. The communications system further comprises a base station controller (BSC) 300 which controls the operation of the base stations, for example when a bot is being handed over from a first base station to a second base station. The BSC is in communication with the computing device and is configured to route messages from the computing device to a bot via the appropriate base station, and vice versa. Known wireless communications systems for use with such automated storage and retrieval systems are disclosed in WO 2015/185726, WO 2018/127437 and WO 2018/177788.

Figure 7 shows a first example of the structure of the frames that are used in the communications system 100. Figure 7a shows a plurality of frames 702, each frame comprising a downlink subframe (DL) and an uplink subframe (UL). Specifically, Figure 7 shows five frames F1 to F5 (shown using reference numerals 702A - 702E respectively). For each of these frames, the downlink subframe and the uplink subframe each occupy a 10 ms time slot and thus a single frame occupies a 20 ms time slot. It can also be seen from Figure 7 that these five frames comprise a multiframe and thus each multiframe occupies a time slot of 100 ms. In the frequency domain, each of the frames (and thus the multiframe) occupies 10 MHz of bandwidth. The communications system transmits a series of multiframes, each of which comprises 5 frames, as discussed above.

Figure 8 shows a schematic depiction of the structure of a subframe that is used in the communications system 100. Each subframe is divided into a plurality of tiles, such that one or more of the tiles can be used to support a communication link between the central computer and a bot. In this example, the subframe is divided into 800 tiles, with 40 subdivisions in the frequency domain (that is, the graphical representation shown in Figure 8 has 40 columns) and 20 subdivisions in the time domain (that is, the graphical representation in Figure 8 has 20 rows). The effective bandwidth of the subframe is 9 MHz and thus each tile corresponds to 225 kHz. The subframe occupies a time slot of 10 ms and thus each tile corresponds to 0.5 ms. The first two columns of tiles (shown by region 810), that is the tiles in the first two time slots of the downlink, are reserved for use for broadcasting messages to the bots and for detecting intrusion by radio signals from other sources. The remaining tiles may be used for dedicated communications links between the central computer and a bot. In one example, a low capacity communications link may comprise two tiles and is used to transmit a command to a particular bot, for example to inform the bot of a grid location to move to, to instruct the bot to retrieve a container or to deposit a container, to report a bot status or a bot data parameter value etc. The bot will confirm receipt of the message and processing of the command by transmitting a message to the central computer using a low capacity communications link in the following uplink subframe. For example, if a message is received in subframe DL3 then it will be acknowledged in subframe UL3. If this is not possible then the bot will wait and respond in subframe UL3 in the subsequent multiframe. Such a low capacity communications link may be referred to as a thin pipe.

When a bot is inducted into the storage system it may be assigned two tiles in a downlink subframe which are exclusively reserved for use by that bot. The tiles may be represented by a unique thin pipe number which can be mapped to the two tiles which are associated with the link. At substantially the same time, the bot will be assigned two tiles in the subsequent uplink subframe which comprise a thin pipe for the bot to use when communicating with the base station. The thin pipe numbers for both the downlink and the uplink thin pipe numbers may be stored in the bot for use in controlling subsequent communications.

Furthermore, a high capacity communications link may be established between the central computer and a bot. Such a high capacity communications link, which may be referred to as a fat pipe, requires 160 tiles and preferably comprises four contiguous rows of tiles in the time domain (that is, the tiles of four consecutive time slots). A fat pipe may be used to recover data from a bot (for example log files, system configurations, etc.), to transmit data to a bot (updating system software etc.) or to enable a bot to be remotely piloted in the event that the bot is not able to direct itself on the grid.

It can be seen from Figure 8 that the number of tiles in the subframe determines the number of thin pipes and fat pipes that may be established. For example, if the tiles in regions 820, 830, 840 & 850 are reserved for 4 fat pipes then only the tiles in the third and fourth time slots of the downlink (shown in Figure 8 by region 815) are available for use for thin pipes. These two time slots comprise 80 tiles and thus it is only possible to form 40 thin pipes. By reserving the tiles of, for example, region 820 for use for thin pipes then this provides an additional 160 tiles, which enables the provision of a further 80 thin pipes. It should be understood that it is possible to reallocate tiles such that the communications system can support more fat pipes and fewer thin pipes (or alternatively, fewer fat pipes and more thin pipes) as is required.

Thus, it can be seen that each downlink subframe can simultaneously support 120 thin pipes and 3 fat pipes. Thus, an entire frame (which comprises 5 downlink subframes) can support 600 thin pipes and 3 fat pipes. It should be understood that a fat pipe will persist across multiple frames as it represents an interaction between the central computer and a bot which lasts for a significant period of time. For example, it may take a number of minutes for a technician to remotely guide a bot back to the repair centre from a distant grid location.

The subframe structure discussed above with reference to Figure 8 is also used for each of the uplink subframes. The tiles in the first two time slots of the downlink (region 810), are reserved for use for detecting intrusion by radio signals from other sources and for other management functions. The remainder of the tiles are reserved for use for transmitting the uplink portions of thin pipes and fat pipes. If, for example, the downlink subframe supports 120 thin pipes and 3 fat pipes then the corresponding uplink subframe will also support 120 thin pipes and 3 fat pipes.

It can be seen from the preceding discussion (see Figure 7) that a bot will respond to a message received from the central computer in the uplink subframe that immediately follows the downlink subframe in which the message was received. For example, if a message is received in downlink subframe DL1 then the bot will respond in uplink subframe UL1 , that is the bot responds within a time period of 10 ms. Thus, the message from the central computer and the response are transmitted in consecutive subframes, which occupy a total time period of 20 ms. However, if the bot is not able to respond within uplink subframe UL1 then it will wait for the UL1 timeslot in the subsequent multiframe to send the response. Thus, it can be seen that rather than responding in 10 ms the response is sent 110 ms later.

In an example of the present disclosure, Figure 9 shows a schematic depiction of an alternative multiframe arrangement in which an offset between a downlink subframe and the associated uplink subframe is applied. Rather than have the uplink subframe immediately follow the associated downlink subframe, an offset is applied. Figure 9a shows a situation where the uplink subframes are offset by one frame. In this example, frame F1 comprises downlink subframe DL1 and uplink subframe UL5 and frame F2 comprises downlink subframe DL2 and uplink subframe UL1. Thus, if a message is sent from the central computer to a bot in downlink subframe DL1 in frame F1 then the response is sent from the bot to the central computer in uplink subframe UL1 in frame F2. It should be understood that uplink subframe UL5 in frame F1 is associated with downlink subframe DL5 from frame F5 in the preceding multiframe.

It can be seen from Figure 9a that each uplink subframe is transmitted in the frame subsequent to the frame in which the associated downlink is transmitted. This means that a response is sent from the bot to the central computer in a time period of 30 ms (and thus the round trip between the central computer and the bot takes a time period of 40 ms). Although this is greater than the 10 ms response time period that can be achieved when there is no frame offset, the chance that a bot is not able to respond in the allotted uplink subframe is significantly reduced, such that there is a much smaller probability of the bot having to use the allocated uplink subframe in the subsequent frame. Thus, by using the frame offset, it is possible to obtain a more reliable and repeatable performance such that virtually all responses are received within 30 ms rather than receiving a minority of responses within 10 ms but a significant majority of responses within 110 ms.

It should be understood that the uplink may be offset by more than one frame within a multiframe. Figure 9b shows a further example in which the uplink subframes are offset by two frames. In this example, frame F1 comprises downlink subframe DL1 and uplink subframe UL4, frame F2 comprises downlink subframe DL2 and uplink subframe UL5 and frame F3 comprises downlink subframe DL3 and uplink subframe UL1. Thus, if a message is sent from the central computer to a bot in downlink subframe DL1 in frame F1 then the response is sent from the bot to the central computer in uplink subframe UL1 in frame F3. It should be understood that uplink subframe UL4 in frame F1 is associated with downlink subframe DL4 from frame F4 in the preceding multiframe (and similarly uplink subframe UL5 in frame F2 is associated with downlink subframe DL5 from frame F5 in the preceding multiframe). Again, by accepting a larger time period in between the transmission of message to a bot and the transmission of the response from the bot then it is hoped that the variation in that response time period is very significantly reduced, or even removed.

The BSC may cause the base station(s) to introduce, vary or remove an uplink subframe offset as required. For example, the BSC may send a uplink_subframe_offset command to the base stations, the details of which are given in Table 1 below:

Table 1 : Uplink subframe command parameter values

It can be seen that for a default value of 0 then the downlink subframe and the uplink subframe are present in the same frame, that is the frames are transmitted as described above with reference to Figure 7. If the value is set to 1 then the uplink subframe is transmitted with a one frame offset to the associated downlink subframe, that is, the frames are transmitted as described above with reference to Figure 9a. The frame structure shown in Figure 9b corresponds to the situation where the uplink_subframe_offset parameter value is set to 2.

A change in the parameter value may be pre-planned such that a broadcast message may be sent to all of the bots to have them stop moving for a pre-determined period of time, for example a few seconds, whilst the uplink_subframe_offset parameter value is changed and the base station(s) adapt. The uplink_subframe_offset parameter may be changed to adapt to bot behaviour and performance. For example, the storage system may operate with the default parameter value of 0 but if it is observed that a proportion of bot response messages are not being transmitted within the expected timescale then a change may be made. For example, if the proportion of bots which respond to a message using the uplink subframe of the subsequent multiframe exceeds a predetermined threshold value then the BSC may increase the uplink_subframe_offset parameter value to 1. Alternatively, the uplink_subframe_offset parameter value may be increased if the proportion of late responding bots exceeds the predetermined threshold value for a given period of time.

The BSC may maintain the uplink_subframe_offset parameter value at 1 for a predetermined period of time, after which it may be reset to zero. Alternatively, the value of uplink_subframe_offset may be further increased if the proportion of late responding bots does not decrease accordingly.

By way of example, Figure 10 shows a schematic depiction of a computer device 1000 used in the implementation of a communications system of the present disclosure that may include a central processing unit (“CPU”) 1002 connected to a storage unit 1014 and to a random access memory 1006. The CPU 1002 may process an operating system 1001 , application program 1003, and data 1023. The operating system 1001 , application program 1003, and data 1023 may be stored in storage unit 1014 and loaded into memory 1006, as may be required. Computer device 1000 may further include a graphics processing unit (GPU) 1022 which is operatively connected to CPU 1002 and to memory 1006 to offload intensive image processing calculations from CPU 1002 and run these calculations in parallel with CPU 1002.

An operator 1007 may interact with the computer device 1000 using a video display 1008 connected by a video interface 1005, and various input/output devices such as a keyboard 1015, mouse 1012, and disk drive or solid state drive 1014 connected by an I/O interface 1004. In a known manner, the mouse 1012 may be configured to control movement of a cursor in the video display 1008, and to operate various graphical user interface (GUI) controls appearing in the video display 1008 with a mouse button. The disk drive or solid state drive 1014 may be configured to accept computer readable media 1016. The computer device 1000 may form part of a network via a network interface 1011 , allowing the computer device 1000 to communicate with other suitably configured data processing systems (not shown). One or more different types of sensors 1035 may be used to receive input from various sources.

It should be understood that the control of the storage system may be performed by an appropriately configured industrial computing device, however the invention may be implemented using virtually any manner of computer device including a desktop computer, laptop computer, tablet computer, wireless handheld or a cloud computing platform. The computing device or devices may execute one or more software instances, for example virtual machines and or containers. The present system and method may also be implemented as a computer-readable/useable medium that includes computer program code to enable one or more computer devices to implement each of the various process steps in a method in accordance with the present invention. In case of more than one computer devices performing the entire operation, the computer devices are networked to distribute the various steps of the operation.

It should be understood that the terms computer-readable medium or computer useable medium comprises one or more of any type of physical embodiment of the program code. In particular, the computer-readable/useable medium can comprise program code embodied on one or more portable storage articles of manufacture (e.g. an optical disc, a magnetic disk, a tape, etc.), on one or more data storage portions of a computing device, such as memory associated with a computer and/or a storage system. In further aspects, the disclosure provides systems, devices, methods, and computer programming products, including non-transient machine-readable instruction sets, for use in implementing such methods and enabling the functionality described previously.

In an alternative arrangement, the storage and retrieval system may be of a size such that a single base station is sufficient to provide radio coverage to the entirety of the grid surface. In such a case, the BSC may be retained as a separate entity or the functionality of the BSC may be incorporated into the base station.

It is envisaged that any one or more of the variations described in the foregoing paragraphs may be implemented in the same embodiment of a communications system.

In this document, the language “movement in the n-direction” (and related wording), where n is one of x, y and z, is intended to mean movement substantially along or parallel to the n-axis, in either direction (i.e. towards the positive end of the n-axis or towards the negative end of the n-axis). In this document, the word “connect” and its derivatives are intended to include the possibilities of direct and indirection connection. For example, “x is connected to y” is intended to include the possibility that x is directly connected to y, with no intervening components, and the possibility that x is indirectly connected to y, with one or more intervening components. Where a direct connection is intended, the words “directly connected”, “direct connection” or similar will be used. Similarly, the word “support” and its derivatives are intended to include the possibilities of direct and indirect contact. For example, “x supports y” is intended to include the possibility that x directly supports and directly contacts y, with no intervening components, and the possibility that x indirectly supports y, with one or more intervening components contacting x and/or y. The word “mount” and its derivatives are intended to include the possibility of direct and indirect mounting. For example, “x is mounted on y” is intended to include the possibility that x is directly mounted on y, with no intervening components, and the possibility that x is indirectly mounted on y, with one or more intervening components.

In this document, the word “comprise” and its derivatives are intended to have an inclusive rather than an exclusive meaning. For example, “x comprises y” is intended to include the possibilities that x includes one and only one y, multiple y’s, or one or more j/s and one or more other elements. Where an exclusive meaning is intended, the language “x is composed of y” will be used, meaning that x includes only y and nothing else. 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).

In one regard, the present invention provides a multiframe communications system for use with a plurality of load handling devices in an automated storage and retrieval system. Each frame of the multiframe comprises a uplink subframe and a downlink subframe. Each of load handling devices has an allocated downlink and uplink subframes an a time offset is applied such that the uplink is transmitted in a different frame to the associated downlink. The offset may be equivalent to one or more frames.

Claims

1. A communication system for a warehouse facility with robots, the communication system comprising: one or more base stations; a plurality of robots configured to move around a grid within the warehouse facility and perform operations, wherein the base stations and the robots comprise means for transmitting and receiving data over communication links; and a communication manager that is configured to define and manage said communication links; wherein the communication links comprise a plurality of low bandwidth communication links configured for communication between the one or more base stations and the robots, and one or more high bandwidth communication links configured for communication between the one or more base stations and one or more of the robots, wherein: each of the communications links comprises a plurality of multiframes; each of the plurality of multiframes comprises a plurality of frames; and each of the frames comprises a downlink subframe and an uplink subframe wherein each of the frames are configured such that the uplink subframe is offset from the associated downlink subframe by one or more frames.

2. A communication system according to claim 1 , wherein each robot is allocated a respective low bandwidth communication link number when the robot is first introduced to the system, the low bandwidth communication link number being stored on the robot, such that each robot has for use a dedicated low bandwidth communication link of the plurality of low bandwidth communication links.

3. A communication system according to claim 2, wherein the low bandwidth communication link number is associated with one of the frames such that a base station communicates with a robot in the downlink subframe of that frame.

4. A communication system according to claim 3, wherein the robot responds to the base station in the uplink subframe of a subsequent offset frame.

5. A communication system according to any of claims 2 to 4, wherein each robot is configured to store the respective low bandwidth communication link number in a non-volatile memory of the robot.

6. A communication system according to any of claims 2 to 5, wherein each robot is configured to receive the respective low bandwidth communication link number as configuration data as part of a boot process.

7. A communication system according to any preceding claim, wherein the low bandwidth communication links are configured for transferring real-time control and position information between the robots and the one or more base stations.

8. A communication system according to any preceding claim, wherein the one or more high bandwidth communication links are allocated to robots dynamically as required.

9. A communication system according to any preceding claim, wherein the one or more high bandwidth communication links are configured for transferring data between the robots and the one or more base stations for configuration purposes during a commissioning or initial phase.

10. A communication system according to any preceding claim, wherein the communication system is configured to map the plurality of low bandwidth communication links and the one or more high bandwidth communication links to frequency and time slot tiles in a time-division duplex sub-frame structure.

11. A communication system according to claim 10, wherein the communication system is configured to adjust a ratio between the number of low bandwidth communication links and the number of high bandwidth communication links in the sub-frame structure.

12. A communication system according to claim 10 or claim 11 , wherein a given low bandwidth communication link occupies two tiles having different frequencies symmetric about a given frequency, in a time slot.

13. A communication system according to any preceding claim, wherein the robots are configured to move across a plurality of paths on the grid, wherein at least some of the plurality of paths intersect with one another.

14. A communication system according to any preceding claim, wherein the low bandwidth communication links are configured for communication within a predetermined latency range.

15. A communication system according to any preceding claim, wherein the latency of the communication links can be adjusted by adjusting at least one parameter associated with the one or more communication links, including frequency usage, tile characteristics, multiplexing/de-multiplexing techniques, timing and code usage.

16. A storage system comprising: a first set of parallel tracks extending in an X-direction, and a second set of parallel tracks extending in a Y-direction transverse to the first set in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces; a plurality of stacks of storage containers located beneath the tracks, and arranged such that each stack is located within a footprint of a single grid space; at least one transporting device, the at least one transporting device being arranged to selectively move in the X and/or Y directions, above the stacks on the tracks and arranged to transport a storage container; a picking station arranged to receive a storage container transported by the at least one transporting device and to transfer an item from the storage container into a delivery container; and a communication system according to any of claims 1 to 15.

17. The storage system according to claim 16, wherein the at least one transporting device has a footprint that occupies only a single grid space in the storage system, such that a transporting device occupying one grid space does not obstruct a transporting device occupying or traversing the adjacent grid spaces in the X and/or Y directions..