Patent Description:
Storage systems comprising a three-dimensional storage grid structure, within which storage containers/bins are stacked on top of each other, are well known. <CIT>) describes a known storage and fulfilment system in which stacks of bins or containers are arranged within a grid framework structure. The bins or containers are accessed by load handling devices operative on tracks located on the top of the grid framework structure. A storage system <NUM> of this type is illustrated schematically in <FIG> of the accompanying drawings.

As shown in <FIG> and <FIG>, stackable containers, known as bins <NUM>, are stacked on top of one another to form stacks <NUM>. The stacks <NUM> are arranged in a grid framework structure <NUM> in a ware-housing or manufacturing environment. The grid framework structure <NUM> is made up of a plurality of storage columns or grid columns. Each grid in the grid framework structure <NUM> has at least one grid column for storage of a stack of containers. <FIG> is a schematic perspective view of the grid framework structure <NUM>, and <FIG> is a top-down view showing a stack <NUM> of bins <NUM> arranged within the grid framework structure <NUM>. Each bin <NUM> typically holds a plurality of product items (not shown), and the product items within a bin <NUM> may be identical, or may be of different product types depending on the application.

The grid framework structure <NUM> comprises a plurality of upright members <NUM> that support horizontal members <NUM>, <NUM>. A first set of parallel horizontal members <NUM> is arranged perpendicularly to a second set of parallel horizontal members <NUM> to form a plurality of horizontal grid structures supported by the upright members <NUM>. The members <NUM>, <NUM>, <NUM> are typically manufactured from metal. The bins <NUM> are stacked between the members <NUM>, <NUM>, <NUM> of the grid framework structure <NUM>, so that the grid framework structure <NUM> guards against horizontal movement of the stacks <NUM> of bins <NUM>, and guides vertical movement of the bins <NUM>.

The top level of the grid framework structure <NUM> includes rails <NUM> arranged in a grid pattern across the top of the stacks <NUM>. Referring additionally to <FIG>, the rails <NUM> support a plurality of load handling devices <NUM>. A first set 22a of parallel rails <NUM> guide movement of the robotic load handling devices <NUM> in a first direction (for example, an X-direction) across the top of the grid framework structure <NUM>, and a second set 22b of parallel rails <NUM>, arranged perpendicular to the first set 22a, guide movement of the load handling devices <NUM> in a second direction (for example, a Y-direction), perpendicular to the first direction. In this way, the rails <NUM> allow movement of the robotic load handling devices <NUM> laterally in two dimensions in the horizontal X-Y plane, so that a load handling device <NUM> can be moved into position above any of the stacks <NUM>.

A known load handling device <NUM> shown in <FIG> comprises a vehicle <NUM> is described in <CIT>), where each load handling device <NUM> only covers one grid space of the grid framework structure <NUM>. Here, the load handling device <NUM> comprises a wheel assembly comprising a first set of wheels <NUM> consisting a pair of wheels on the front of the vehicle <NUM> and a pair of wheels <NUM> on the back of the vehicle <NUM> for engaging with the first set of rails or tracks to guide movement of the device in a first direction and a second set of wheels <NUM> consisting of a pair of wheels <NUM> on each side of the vehicle <NUM> for engaging with the second set of rails or tracks to guide movement of the device in a second direction.

The load handling device (not shown) is equipped with a lifting device or crane device to lift a storage container from above. The lifting device comprise a set of lifting tethers extending in a vertical direction and connected at the four corners of a lifting frame (not shown), otherwise known as a grabber device (one tether near each of the four corners of the grabber device) for releasable connection to a storage container. The grabber device is configured to releasably grip the top of a storage container to lift it from a stack of containers in a storage system of the type shown in <FIG> and <FIG>.

Although not shown in <FIG>, the load handling device <NUM> is powered during operation by an on-board rechargeable battery. Examples of rechargeable batteries are Lithium-Ion battery, Nickel-Cadmium battery, Nickel-Metal Hydride battery, Lithium-Ion Polymer battery, Thin Film battery and Smart battery Carbon Foam-based Lead Acid battery. The battery is recharged while the load handling device <NUM> is operative on the grid framework structure <NUM> by a charge station <NUM> shown in <FIG>. The charge station <NUM> is typically an L shaped structure that is fixed proximate to the grid framework structure <NUM> and extends over a nominal grid cell at an edge of the grid structure. The charge station comprises a charge head <NUM> comprising charge contacts which are fixed in position relative to the charge station. The charge head is mounted to one arm <NUM> of the L shaped structure such that the charge head <NUM> is suspended over at least two grid spaces of the grid framework structure. A load handling device may be charged by being instructed to move to a grid cell above which the charge head is located. As the load handling device moves into the grid cell, a contact is made between a charge contact pad on a top surface of the load handling device, and the charge contacts of the charge head <NUM>. A charge is imparted to the load handling device from the charge contacts through the charge contact pad situated on the top surface of the load handling device.

However, a number of problems exist with the charge station. In particular, due to the movement of the robotic load handling device into the charge station, a clamping force exists between the charge contacts and the robotic load handling device. However, the magnitude of this force can cause problems to arise over a period of time. For example, repeated entries of the robotic load handling device into the grid cell above which the charge station is located causes a fatiguing of the charge station which will then require maintenance or replacement of the charge head and supporting structure. Moreover, vibration of the grid framework structure caused by movement of the robotic load handling devices negatively affects the alignment between the charge contacts of the charge station and the robotic load handling device. Moreover, grid cell damage, wear and material creep causes alignment issues between the charge contacts and the charge pad contacts negatively affecting the ability of the robotic load handling device to make contact with the charge contacts. Similarly, tolerances in both the manufacture of the grid framework structure and charge station and/or slight variation in installation alignment of the grid framework structure with respect to the charge station and/or thermal expansion of the grid framework structure with respect to the charge station can also cause alignment issues which negatively affect the ability of the robotic load handling device to make contact with the charge contacts. Moreover, the charge contacts wear with time and therefore, require periodic servicing or repair. However, the maintenance of the charge contacts requires human intervention on the top of the grid framework structure which can only be performed if the robotic load handling devices on top of the grid framework structure are in a "safe mode" rendering them inoperable. The downtime as a result of the load handling device being idle leads to a loss of production of the whole system.

<CIT>) addresses this problem by providing a charge station in which a charge head <NUM> is drawn towards the charge pad on the top surface of the load handling device. The charge unit (see <FIG>) comprises a plurality of profiled sections <NUM>, <NUM> arranged to interface with a hoist element <NUM> of the handling device <NUM> (see <FIG>) and a power transfer component <NUM> arranged to transfer power to the load handling device when the hoist element <NUM> engages with the plurality of profiled sections <NUM>, <NUM>. <FIG> shows a hoist element <NUM> used for manual movement of the load handling device <NUM>. The hoist element <NUM> comprises a cutaway below a bulbous head which gives rise to an underside <NUM>. The hoist element <NUM> is so designed to permit the attachment of a hoist to lift the load handling device <NUM> from a grid cell. The power transfer component <NUM> is typically composed of copper and outwardly biased by a resiliently member, e.g. a spring, so as to lessen the impact of the power transfer unit <NUM> making contact with a charge pad <NUM> on the top surface <NUM> of the load handling device <NUM>. In addition to the power transfer unit <NUM>, the cartridge <NUM> comprises a plurality of charge contacts <NUM> on its underside. Like the power transfer unit <NUM>, the plurality of charge contacts <NUM> are outwardly biased by resilient member, e.g. a spring, so as to lessen the impact of the charge contacts <NUM> making contact with the charge pad <NUM> on the top surface <NUM> of the load handling device <NUM>. In contrast to the power transfer units <NUM>, the additional charge contacts may be for the purpose of preventing arcing between the power transfer units or data transfer during charging.

The plurality of profiled sections <NUM>, <NUM> and the power transfer unit <NUM> are arranged in a moveable cartridge <NUM> such that contact between the hoist element <NUM> and the plurality of profiled sections <NUM>, <NUM> causes movement of the cartridge <NUM> towards the load handling device and thereby, control the amount of clamping force of the cartridge <NUM>, in particular the power transfer unit <NUM> with the charge pad <NUM> at the top surface of the robotic load handling device. Together with the resiliently biased power transfer units <NUM> and/or the plurality of resiliently biased charge contacts <NUM>, damage/wear to the cartridge and/or the top surface of the robotic load handling device is minimised.

However, the increased number of components of the cartridge such as the plurality of profiled sections not only increases the complexity of the charge station but renders the charging station costly to service should any one of the components require repairing or to be replaced. Moreover, since the cartridge needs to be suspended above the load handling loading device during charging, the cartridge would need to be externally mounted to a dedicated support structure. Such a support structure presents an unsightly obstacle and is an eyesore amongst the grid framework structure. In some cases, the structure supporting the charge head obscures the view of the grid framework structure and the load handling devices traversing on the grid framework structure. Furthermore, the need to suspend the cartridge above the load handling device runs the risk of potentially causing alignment issues between the charge contacts of the cartridge and the hoist element of the load handling device during a charging regime. In an extreme case, this can lead to improper seating of the hoist element with the profiled sections of the charge head resulting in improper electrical coupling between the charge contacts on the top surface of the load handling device and the cartridge of the charging station resulting in either inadequate or prolonged charging of the battery. Other considerations where misalignment of the load handling device with the charge station that can negatively impact the proper operation of the load handling device is the risk of arcing between the power transfer components of the charge station and the charge contacts of the load handling device.

<CIT>) discloses a load handling device according to the preamble of claim <NUM>, wherein charge receiving elements for charging the battery is mounted to the underside of a container vehicle or load handling device and is arranged to electrically couple with charge providing elements of a charge station located within a single grid cell at a level below the rails on the grid framework structure. In operation, the container vehicle or the load handling device is moved to a position above the charging station such that the charge receiving elements on the underside of the container vehicle is directly above the charge providing elements of the charge station within a grid cell; more specifically their corresponding contact surfaces are directly facing each other. Electrical contact or coupling is achieved by lowering the container vehicle vertically towards the rail grid, e.g. by vertically displacing a set of wheels of the container vehicle, such that the corresponding contact surfaces of the charge receiving elements and the charge providing elements mate. Lowering of the container vehicle towards the rail grid pushes the contact surfaces of the charge receiving elements to mate against the contact surfaces of the charge providing elements of the charge station. The charge receiving elements or the charge providing elements may be connected to a resilient assembly to bias the charge receiving elements or the charge providing elements in a vertical direction. Integrating the charge station within a single grid cell of the grid framework structure and at a level below the rails of the rail grid permits the charging station to be located anywhere on the rail grid without preventing movement of the container vehicle. The downside of the storage system taught in <CIT>) is that it is necessary that the container vehicle is equipped with a crane device that comprises a cantilever arm that extends laterally from the top of the vehicle to accommodate a container receiving space, i.e. the container is accommodated beneath the cantilever arm and is held above the level of the rails. Equally, the vehicle needs to be sufficiently heavy to counterbalance the weight of a container and to remain stable during a lifting process. As a result, the container vehicle including the container receiving space has a footprint that extends over at least two grid cells.

A charging station is thus required that:.

In addition to the above, a container vehicle or load handling vehicle for cooperation with the charging station is require that has a footprint of substantially only a single grid space or cell. It is against this background that the present invention has been devised.

This application claims priority from UK Patent Application Nos. <CIT> and <CIT>.

The present applicant has mitigated the above problem by providing a load handling device for lifting and moving containers stacked in a storage system comprising a grid framework structure supporting a pathway arranged in a grid pattern above the stacks of containers, the load handling device comprising:.

For the purpose of this patent specification, the storage system for the storage of goods, retrieval, processing and/or fulfilment of orders, wherein access to such goods is provided by fully or semi-automatic retrieval by the load handling devices is referred to as a grid framework structure or "hive". The grid framework structure or "hive" provides pathways in the form of a grid-layout for the movement of the load handling devices to traverse and perform operations at various location in the "hive". Preferably, the rechargeable power source may be a battery or a capacitor. The charge station is connected to a suitable power source charger, preferably a DC power source charger. For example, the power source charger comprises a rectifier to convert AC current to DC current. Preferably, the vehicle body is mounted on two sets of wheels, each of the two sets of wheels being arranged for engaging with the rails on the grid framework structure. Optionally, the vehicle body houses the lifting device comprising the lifting drive assembly and the grabber device such that the grabber device is configured, in use, to releasably grip a container and lift the container from a stack in the grid framework structure into a container-receiving space. The container receiving space may comprise a cavity or recess arranged within the vehicle body, e.g. as described in <CIT> (Ocado Innovation Limited). Alternatively, the vehicle body of the load handling device may comprise a cantilever as taught in <CIT> (Autostore Technology AS) in which case the container receiving space is located below a cantilever of the load handing device. In this case, the grabber device is hoisted by a cantilever such that the grabber device is able to engage and lift a container from a stack into a container receiving space below the cantilever. Optionally, the vehicle body houses the rechargeable power source. Optionally, the pathway comprises a plurality of rails or tracks. The plurality of rails or tracks are arranged in a grid pattern.

By adapting the lifting device for lifting and moving containers stacked in a storage system to additionally comprise an electrical charge point for electrically coupling with a charge head of a charge station, the lifting device is permitted to double up as an electrical charge point for charging the rechargeable power source. Preferably, the grabber device comprises the charge point of the lifting device. More preferably, the electrical charge point comprises at least two charge receiving pads connectable to at least two charge providing pads of the charge head. For the purpose of the present application, the contact surfaces of the charge providing pads and the charge receiving pads may also be termed current conducting surfaces since they conduct the electric current used to charge the rechargeable power source. Not only does such an adaptation simplify the make-up of the load handling device, since the need to have electrical contact pads mounted to the surface of a top wall of the load handling device is no longer required, but the adaptation also removes the need to have an externally mounted charge station suspending the charge head that is specially adapted to cooperate with the electrical charge point of the load handling device and thereby, mitigate potential misalignment issues with the charge head of the charge station. Other benefits include the removal of an externally mounted charge station proximate to the grid framework structure obscuring the view of the load handling devices on the grid framework structure and therefore, providing a "cleaner" grid framework structure with fewer obscurities. As a result of the adaptation of the lifting device to comprise the electrical charge point for charging the rechargeable power source allows the charge station to be integrated within the grid framework structure or hive, more specifically within a single grid space of the grid framework structure and therefore, occupies a space which is considered dead space within the grid framework structure.

For high volume operations involving multiple product lines arranged in storage containers or totes, the speed of operation of the load handling devices on the grid framework structure is critical to make sure that demand for the retrieval of storage items is met. To maximise the speed of operation of the load handling devices, the performance of each of the load handling devices on the grid framework structure needs to be maximised, in terms of battery or capacitor life, reliability, lifting capacity, stability and so on. As a result, the location of the charge station of the present invention being integrated within the grid framework structure has an influence on the speed of operation of the load handling devices, in particular during high volume operation involving multiple product lines. Locating the charge station proximate the grid framework structure, more specifically at the edge of the grid framework structure as found in prior art systems, generally has a negative impact on the speed of operation of the system since the load handling devices will have to travel relatively large distances across multiple grid spaces to dock onto the charge station, let alone to make sure that the charge point suitably aligns with charge head of the charge station. Locating multiple externally mounted charger stations at different locations around the edge of the grid framework structure to increase the speed of operation of the storage system and thereby, minimise the time the load handling devices remain idle will greatly obscure the view of the load handling devices operational on the grid framework structure. As the health of the load handling devices is monitored by CCTV cameras, such externally mounted charge stations may impact the monitoring of the load handling device in certain areas on the grid framework structure. By integrating the charger station within the grid structure, multiple charge stations can be accommodated within the grid framework structure without obscuring the view of the load handling devices traversing on the grid structure.

Preferably, the charge station is sized to fit inside a single grid space of the grid framework structure. Integrating the charge station of the present invention within the grid framework structure greatly increases the density of charge stations that can be accommodated by the grid framework structure and thereby, increases the accessibility of a nearby charge station for any given load handling device on the grid framework structure. This in turn increases the speed of operation of the storage system as the travel time to a nearby charge station is significantly reduced in comparison to travelling to an externally mounted charge station at the edge of the grid framework structure.

The grabber device is sized to descend within a grid space of the grid framework structure and engage with a container located within the grid space. To dock onto the charge station according to the present invention, preferably the electrical charge point is mounted to the grabber device such that the lifting device is configured to raise and lower the electrical charge point relative to the container receiving space so that in a lowered position the electrical charge point is configured to engage with the charge head of the charge station. The charge station of the present invention is sized to fit inside a single grid space or grid cell of the grid framework structure. Mounting the electrical charge point to the grabber device increases the functionality of the grabber device to not only have the ability to pick containers within a given grid space but also have the flexibility to electrically couple with a charge station within the grid framework structure.

Preferably, the grabber device is suspended from the body of the load handling device by a tether that can be extended and retracted from the load handling device to move the grabber device vertically. Optionally, the grabber device is suspended from the body of the load handling device by four tethers. Where the container receiving space is a cavity or recess within the vehicle body, this could be from within the vehicle body or alternatively, where the vehicle body includes a cantilever, the grabber device is suspended from the cantilever of the vehicle body. Preferably, the tether is in the form of a tape or band or a rope. Preferably, the charge receiving pads are electrically coupled to the rechargeable power source by one or more electrical cables having a first end electrically coupled to the recharge power source in the body of the load handling device and a second end electrically coupled to the electrical charge point of the grabber device, more specifically the charge receiving pads. Optionally, the one or more electrical cables is at least partially covered in an electrically insulating sheath. Optionally, the one or more electrical cables can be one or more of the tethers used to suspend the grabber device from the body of the load handling device. Power can be transferred to the load handing device to charge the rechargeable power source via one or more of the tethers suspending the grabber device or alternatively, using a dedicated electrical cable that is separate to the tethers supporting the grabber device. Using at least two of the lifting tethers to carry the current to the rechargeable power source reduces the need to have a dedicated cable to carry the current to the rechargeable power source. However, the present invention is not restricted to transferring power to the rechargeable power source via the lifting tethers and for convenience, separate electrical cables to transfer power to the rechargeable power source falls within the scope of the present invention. Preferably, the grabber device is formed as a frame comprising four corner sections, a top side and a bottom side. More preferably, four gripper elements for engaging with a container are arranged at the bottom side of the frame. Preferably, the grabber device comprises a vertical guide or a locating pin at each corner of the frame to guide the grabber device into engagement with the container. To ensure that the gripper elements of the grabber device properly align with corresponding receiving portions in the rim of the container when engaging with the container, the grabber device comprises at least one vertical guide or locating pin that seats in corresponding cut-outs in the container; typically at each corner of the container. Thus, in order for the grabber device of the present invention to engage with the charge station, the charge station of the present invention mirrors the engagement features of a container, e.g. cut-outs or holes, to help the gripper elements to properly align with corresponding receiving portions in the charge station, more specifically the charge head of the charge station. In addition to alignment of the gripper elements, locating pins help the charge receiving pads to be in registration alignment with the charge providing pads of the charge head when the grabber device of the present invention engages with the charge station. Preferably, the electrical charge point releasably latches onto the charge head of the charge station. Preferably, the grabber device comprises at least two gripper elements to releasably latch to the charge head of the charge station. Optionally, the electrical charge point comprises the at least two gripper elements. Here, power (current) can be transferred to the rechargeable power source via the least two gripper elements engaging with the charge head of the charge station. Optionally, the electrical charge point may comprise one or more interface pins or charge pads. For example, the electrical charge point is arranged to cooperate with the charge head of the charge station by a plug and socket type configuration. Instead of physically engaging with the charge head of the charger station, the electrical charge point is arranged to cooperate with the charge head by a floating electrical connector. For example, power can be transferred between the electrical charge point and the charge head of the charge station by induction charging. This removes the need to have any physically contact of the charging pads when transferring power to the rechargeable power source.

A charge station comprises a charge head arranged for cooperating with the electrical charge point of the lifting device, more specifically the grabber device of the load handling device of the present invention. Optionally, the charge station comprises a raised platform comprising the charge head. Preferably, the charge head comprises one or more electrical contact surfaces. Preferably, the one or more electrical charge surfaces is an electrical charge providing pad. Preferably, the platform has one or more engagement features, e.g. cut-outs or holes that engage with the gripper elements and/or the locating pins of the grabber device. Preferably, the gripper elements engage with the cut-outs or holes in the platform so as to draw the charge receiving pads of the grabber device with the charge providing pads of the charge head.

Preferably, the charge head is incorporated into a calibration tool for calibrating the lifting device, wherein the platform is raised above a predetermined height above the floor such that there is a predetermined separation between the raised platform and the container receiving portion of the load handling device; preferably a predetermined separation from the lifting device. The calibration tool is used to ensure that the lifting tethers suspending the grabber device descend a fixed depth down a given grid space whilst ensuring that the grabber device is kept horizontal during operation to engage with a container. The grabber device is suspended from a tether that can be extended and retracted from the load handling device to move the grabber device vertically. The depth by which the grabber device descends vertically into a single grid space into engagement with the container is set during manufacture of the load handling device. This depth is dependent on a number of factors such as the number of containers stacked in given grid space. Typically, this depth can be calculated knowing the height of the containers which are of nominally fixed height. Through knowledge of the number of containers in a stack, a controller can determine the depth by which the grabber device must descend to engage with a container in the stack. Thus, depending on the number of containers in a stack, the controller can instruct the grabber device of the load handling device to descend a predetermined depth to engage with a container from a stack in a grid space.

Typically, the grabber device is adapted to engage with the top of the container, e.g. mate with corresponding engagement features in the rim that forms the top surface of the container. Individual containers may be stacked in vertical layers, and their locations in the grid framework structure or "hive" may be indicated using co-ordinates in three dimensions to represent the load handling device or a container's position and a container depth (e.g. container at (X, Y, Z), depth W). Equally, locations in the grid framework structure may be indicated in two dimensions to represent the load handling device or a container's position and a container depth (e.g. container depth (e.g. container at (X, Y), depth Z)). For example, Z=<NUM> identifies the uppermost layer of the grid, i.e. the layer immediately below the rail system, Z=<NUM> is the second layer below the rail system and so on to the lowermost, bottom layer of the grid.

It is essential during a picking operation that the grabber device remains horizontal at all times, particularly when engaging with a storage container, otherwise there is the potential risk that at least one of the tethers holding the grabber device may tear if subjected to unbalanced and high loads. To ensure that the grabber device remains horizontal, is it is important that the length of all of the tethers is kept the same at all times. To obtain the correct length of all of the tethers relative to the grabber device such that the grabber device is kept horizontal during operation, the length of each of the tethers must be adjusted both initially, as well as at various service intervals since they tend to elongate or stretch over time which can be attributed to numerous factors such as environmental, motor wear, stretching of the tether and so on. In an extreme case, the grabber device may fail to engage with the container either because its descent falls too short or overshoots the container. Commonly, the tethers are connected and spooled onto separate reels arranged at an upper level within the housing of the load handling device. To adjust a tether, the corresponding reel may be disconnected from a rotational shaft and the tether adjusted by free rotation of the reel or spool relative the rotational shaft. The reel or spool is subsequently fastened to the rotational shaft when the tether has the desired length. A variant to this method is to provide adjustable lifting tether connectors fixed to the grabber device as taught in <CIT>).

Preferably, at least one of the tethers supporting the grabber device is formed as a tape or band, preferably a metallic tape or band.

The calibration tool is used to ensure that the grabber device of the lifting device descends a fixed depth down a given grid space whilst ensuring that the grabber device is kept horizontal during operation to engage with a container. The raised platform of the calibration tool comprise engagement features that mirror the engagement features of a typical container. To calibrate the lifting device of a load handling device, in particular to ensure that there is no slack in any of the tethers supporting the grabber device, the load handling device is instructed to traverse over a grid space accommodating the calibration tool and descend the grabber device to engage with the engagement features of the calibration tool, i.e. the gripper elements engage with corresponding receiving portions in the calibration tool. Once locked onto the platform, the winch is operated to pull the lifting tethers under tension. When under tension, the spool is adjusted to this new setting. Equally, where the grabber device falls short of the platform, the winch is instructed to wind out the lifting tether until the grabber device engages with the calibration tool, and then the lifting tethers are placed under tension once the grabber device is engaged with the calibration tool.

In a preferred embodiment of the present invention, the charge head for charging the battery of a load handling device can be incorporated into the calibration tool for calibrating the lifting device of the load handling device. Preferably, the calibration tool comprises the charge head arranged to electrically couple with the electrical charge point of the lifting device. Preferably, the charge head of the charge station comprises one or more contact surfaces or charge providing pads for electrically coupling with the charge point of the lifting device; more preferably the charge surfaces are mounted to the platform of the calibration tool. By incorporating the charge station into the calibration tool, calibration of the lifting device and charging of the battery can happen in situ during a calibration operation, thereby improving the efficiency of operation of the storage system which in turn removes the need to treat both processes of calibration of the lifting tethers and charging of the battery separately.

The present invention also provides a storage system according to claim <NUM>.

The load handling device is operatively arranged to traverse over a grid space occupying a charge station and charge the rechargeable power source in the load handling device by engaging the grabber device with the charge station. Optionally, the first set of parallel pathways comprises a first set of parallel rails or tracks and the second set of parallel pathways comprises a second set of parallel rails or tracks. The pathway includes but is not limited to rails or tracks.

Preferably, the grabber device is configured to engage with and/or disengage from the charge station in response to a signal from a controller. Preferably, the controller actuates an actuator to engage with and/or disengage from the grabber device from the charge station. More preferably, the signal represents a condition of the rechargeable power source, whereby the condition is any one of voltage, and/or current, and/or temperature, and/or state of charge and/or depth of discharge. Actuation of the grabber device to engage with and disengage from the charge head of the charge station is in response to a condition of the rechargeable power source, whereby the condition is any one of voltage, and/or current, and/or temperature, and/or state of charge and/or depth of discharge. For example, the controller actuates the grabber device to disengage from the charge head in response to the controller sensing that the rechargeable power source has reached a predetermined depth of charge.

The present invention provides a method for charging a rechargeable power source in a load handling device of the present invention, comprising the steps of claim <NUM>.

Preferably, the method further comprises the steps of:.

Further features and aspects of the present invention will be apparent from the following detailed description of an illustrative embodiment made with reference to the drawings, in which:.

<FIG> shows a load handling device <NUM> according to an embodiment of the present invention and described in International patent application <CIT> (Ocado Innovation Limited). The load handling device <NUM> comprises a vehicle body <NUM> equipped with a lifting mechanism (not shown) comprising a winch or a crane mechanism to lift a storage container or bin <NUM>, also known as a tote, from above. The crane mechanism comprises a winch cable <NUM> wound on a spool or reel and a grabber device <NUM>. The grabber device <NUM> is configured to grip the top of the container <NUM> to lift it from a stack of containers in a storage system of the type shown in <FIG> and <FIG>. Typically, the grabber device <NUM> is configured as a frame and four lifting tethers <NUM> are fixed to each corner of the grabber device <NUM> (see <FIG>). Further details of the grabber device are discussed below.

The vehicle body <NUM> comprises an upper part and a lower part (see <FIG>). The lower part is fitted with two sets of wheels <NUM>, <NUM>, which run on rails at the top of the grid framework structure of the storage system. Each of the set wheels are driven to enable movement of the vehicle in X and Y directions respectively along the rails. One or both sets of wheels can be moved vertically to lift each set of wheels clear of the respective rails, thereby allowing the vehicle to move in the desired direction.

The wheels are arranged around the periphery of a cavity or recess, known as a container-receiving space <NUM>, in the lower part. The recess <NUM> is sized to accommodate the container <NUM> when it is lifted by the crane mechanism, as shown in <FIG> (a and b). When in the recess, the container is lifted clear of the rails beneath, so that the load handling device can move laterally to a different location. On reaching the target location, for example another stack, an access point in the storage system or a conveyor belt, the bin or container can be lowered from the container receiving portion and released from the grabber device <NUM>.

The upper part of the vehicle body <NUM> may house a majority of the bulky components of the load handling device. Optionally, the vehicle body houses the rechargeable power source. <FIG> shows a perspective view of the load handling device with the outer casing housing the bulky components removed. Typically, the upper part of the vehicle houses a driving mechanism <NUM> for driving both the wheels and the lifting mechanism together with an on-board rechargeable power source for providing the power to the driving mechanism and the lifting mechanism. The rechargeable power source can be any appropriate battery, such as, but not limited to, lithium batteries or even a capacitor. For the purpose of explanation of the present invention, the rechargeable power source is a battery. It is perfectly feasible in the present invention that any of the bulky components such as the rechargeable power source to be located anywhere in the body of the vehicle <NUM>, e.g. in the lower part of the vehicle to lower the centre of gravity of the load handling device <NUM> and thereby improve the stability of the load handling device. To provide a container receiving space within the body of the load handling device, preferably the rechargeable energy source is integrated into one of the side walls of the body of the vehicle <NUM>.

Whilst the container receiving space <NUM> for accommodating a container when it is lifted by the crane mechanism is arranged within the vehicle body <NUM> shown in <FIG>, the present invention is not limited to the container receive space <NUM> being located within the vehicle body <NUM>. The present invention is also applicable to the container receiving space being located below a cantilever such as in the case where the vehicle body of the load handling device has a cantilever construction as described in <CIT>. For the purpose of the invention, the term 'vehicle body" is construed to optionally cover a cantilever such that the grabber device is located below the cantilever. However, for ease of explanation of the present invention, the container receiving space for receiving a container is arranged within a cavity or recess within the vehicle body.

The driving mechanism <NUM> typically comprises three main sets of motors: Z-drive motors used to raise and lower winch tethers, which are wound onto spools mounted on drive shafts; an X-drive motors which drives a first set of wheels and a Y-motors which drives a second set of wheels. However, the number of motors to drive the first and second sets of wheels and the lifting mechanism is not limited to three sets of motors and the number of motors is dependent on the availability of space within the vehicle body and the complexity of the drive mechanism to drive both the wheels and the winch mechanism. For example, each of the first and second sets of wheels can by driven by individual hub motors in the lower part of the vehicle to provide four wheel drive capability of the load handling device on the grid framework structure. This is to allow the load handling device to able to travel along the rails or tracks on the grid framework structure should anyone of the wheels in the set slip on the rail or track. Equally, each of the lifting tethers <NUM> can be operated by separate motors. For example, in the particular embodiment of the present invention shown in <FIG>, four lifting tethers <NUM> are shown, each of the four lifting tether <NUM> at each corner of the grabber device <NUM> and whereby four separate motors are used to wind the four lifting tethers on separate spools. Whilst the particular embodiment of the present invention describes the load handling device travelling along rails or tracks, the load handling device can travel along any pathway on the grid framework structure and is not limited to travelling on rails or tracks. The pathway can be any surface including but not limited to rails or tracks.

The lifting mechanism used to lift the containers into the container receiver portion can take any suitable form. For maximum stability and load capacity, commonly four lifting tethers <NUM> are used to winch the grabber device <NUM>, with one tether disposed nearby or at each of the corners of the grabber device <NUM>, but a different arrangement, for example with fewer tethers, could be used if desired. One end, e.g. first end, of each of the tethers is wound on the spool in the load handling device and the other end, e.g. second end, is fixed to the grabber device <NUM>, typically at each corner of the grabber device, by a suitable bracket (not shown). The number of tethers attached to the grabber device is dependent on the ability to maintain the grabber device horizontal during operation when picking up a container <NUM> and the ability to withstand the tension applied to the tethers when lifting containers, which could weigh up to <NUM>, without extending or stretching, i.e. be inextensible under a predetermined applied tensile stress. To possess the necessary physical properties (Young's Modulus), the tethers are generally in the form of a cable, e.g. rope or even a tape, but other tethers with the necessary physical properties to winch containers are permissible in the present invention. In addition to having the necessary elastic modulus, two of the tethers can be made electrically conductive to transfer power from the charge station via the grabber device to the battery in the vehicle body <NUM> of the load handling device <NUM> according to the present invention, i.e. one of the tethers providing DC- and the other tether providing DC+. Preferably, the tethers are metallic. In addition to being able to conduct electricity, the tethers should be resistant to corrosion. Commonly, the tethers are composed of stainless steel but other metallic materials with the above properties are permissible in the present invention. Two of the tethers that are selected to conduct electricity to charge the battery is electrically insulated in an electrically insulating sheath, e.g. a thermoplastic sheath or other suitable polymer material. Whilst other types of tether material with the necessary physical and electrical properties are permissible in the present invention, for the purpose of explanation of the present invention and what is commonly used in practice, the tethers are in the form of a tape or band and composed of stainless steel. Having the tethers in the form of a tape allows the tether to be compactly wound onto the spool or reel of the winch in the body <NUM> of the load handling device <NUM> whilst providing the necessary cross-sectional area to carry large currents which can be in the order of <NUM> amps.

As discussed above, connected to the ends of the tethers <NUM> is the grabber device <NUM> as shown in <FIG>. In the particular embodiment shown in <FIG>, the grabber device <NUM> is formed as a frame having four corner sections, a top side <NUM> and a bottom side <NUM>. To grab a container <NUM>, the grabber device <NUM> comprises four locating pins or guide pins <NUM> nearby or at each corner of the grabber device <NUM> which mate with corresponding cut outs or holes <NUM> formed at four corners of the container <NUM> and four gripper elements <NUM> arranged at the bottom side of the grabber device <NUM> to engage with the rim of the container (see <FIG>). The locating pins <NUM> help to properly align the gripper elements <NUM> with corresponding holes in the rim of the container.

In the particular embodiment shown in <FIG>, each of the gripper elements <NUM> comprises a pair of wings that are collapsible to be receivable in corresponding holes <NUM> in the rim of the container and an open enlarged configuration having a size greater than the holes <NUM> in the rim of the container in at least one dimension so as to lock onto the container (see <FIG>). The wings are driven into the open configuration by a drive gear. More specifically, the head of at least one of the wings comprises a plurality of teeth that mesh with the drive gear such that when the gripper elements <NUM> are actuated, rotation of the drive gear causes the pair of wings to rotate from a collapsed configuration (<FIG>) to an open enlarged configuration (<FIG>).

When in the collapsed or closed configuration, the gripper elements <NUM> are sized to be receivable in corresponding holes <NUM> in the rim of the container as shown in <FIG>. The foot of each of the pair of wings comprises a stop <NUM>, e.g. a boss, such that when received in a corresponding hole <NUM> in the rim of the container, the stop engages with an underside of the rim when in an enlarged open configuration to lock onto the container when the grabber device <NUM> winched upwards towards the container-receiving portion of the load handling device.

The gripper elements <NUM> are received in the holes in the rim of the container when the grabber device <NUM> is at a predetermined height above the rim of the container as measured by one or more depth sensors (not shown) mounted to the underside of the grabber device. At this depth, the gripper elements <NUM> are actuated to grab the container <NUM> in response from a signal from the one or more of the depth sensors mounted to the underside of the grabber device <NUM>. The predetermined height is determined through calibration of the grabber device either with a container of known height or a calibration tool (see <FIG>) having a raised platform that is representative of the height of a container. Further detail of the calibration is discussed below. When the grabber device is at the predetermined height above the container as measured by the depth sensor, which is an indication that the gripper elements are received within the holes in the rim of the container as shown in <FIG>, a controller sends a signal to the drive gear to actuate the gripper elements <NUM> to the enlarged open configuration, i.e. having a size larger than the holes in at least one dimension, in order to grab the container. Various types of depth sensors commonly known in the art for measuring depth or height are permissible in the present invention. Examples of depth sensors include but are not limited to light sensors, camera sensors, ultrasonic sensors, plunger etc. Equally and/or additionally the gripper elements <NUM> can be actuated by determining the number of rotations of the spool or reel carrying the lifting tape (lifting tether) such that when the rotation of the spool reaches a predetermined rotation necessary for the gripper elements <NUM> to engage with the holes <NUM> in the rim of the container, the gripper elements <NUM> are actuated to grip the container from above.

According to an embodiment of the present invention, power is transferred from the grabber device <NUM> to the battery situated in the load handling device <NUM> via two of the lifting bands <NUM> holding the grabber device <NUM>, i.e. one providing DC- and the other providing DC+. As discussed above, two of the lifting bands <NUM> can be made electrically conductive to transfer power from the charge station to the battery held in the load handling device via the grabber device <NUM>. Electrical connection between the grabber device <NUM> and the lifting band <NUM> can be made by one or more electrical terminal blocks located within the grabber device.

The charge station is connected to a suitable power source charger, preferably a DC power source charger. Whilst it is convenient to utilise two of the lifting bands <NUM> to transfer power to the battery, power can be transferred to the battery by two dedicated electrical cables that extend from the grabber device to electrically couple with the battery in the body of the load handling device. The grabber device can comprise at least two charge contacts or charge receiving elements (or collectors) having current conducting surfaces on its underside to electrically couple with at least two charge pads or charge providing elements having corresponding current conducting surface on the top surface of a charge station (see <FIG> and <FIG>).

<FIG> shows a perspective view of the grabber device <NUM> according to an embodiment of the present invention. All of the features of the grabber device commonly present in a known grabber device discussed above to lift a container from a stack such as the locating pins <NUM> and the gripper elements <NUM> are present in the grabber device <NUM> of the present invention. In addition to the gripper elements <NUM> for engaging with the rim of the container, the grabber device <NUM> further comprises an electrical charge point <NUM> in the form of two or more charge receiving pads <NUM> arranged to cooperate with a charge head of a charge station in the form of two or more charge providing pads (not shown). The charge receiving pads <NUM> and/or the charge providing pads are resilient biased in a vertical direction towards each other to increase the contact force between the corresponding contact surfaces of the charge head of the charge station. The charge receiving pads <NUM> are mounted to the bottom side <NUM> of the grabber device <NUM> so as to electrically couple with the charge providing pads of the charge station when the contacts surfaces of the contact pads come together. Further detail of the charge station according to an embodiment of the present invention is discussed further below.

Instead of the provision of separate charge receiving pads mounted to the grabber device <NUM>, equally or additionally, at least two of the gripper elements <NUM> itself can be used to electrically couple to the charge station when the grabber device <NUM> engages with the charge station, i.e. the gripper elements <NUM> comprises the electrical charge point <NUM>. For example, the gripper elements <NUM> can engage with corresponding charge providing elements of the charge station. The gripper elements <NUM> can be made electrically conductive to at least two lifting tethers by suitable wiring so as to transfer power from the charge station to the battery via the gripper elements <NUM>. Two of the lifting tethers used to carry current to the battery can be made electrically insulating by an electrically insulating sheath. Equally, power can be transferred to the battery via the gripper elements <NUM> by at least two dedicated electrical cabling.

In the particular embodiment of the present invention, two charge point or charge receiving pads are shown on the underside of the grabber device <NUM> that electrically couple with two contact pads or charge providing pads on the top surface of the charge station. Two of the charge points or charge receiving pads on the grabber device <NUM> are electrically contactable to two charge pads or charge providing pads of the charge station. As the charge providing pads of the charge station provide a direct current, one of the charge providing pad is DC- and the other charging providing pad is DC+. Although <FIG> shows four charge points <NUM>, electrical coupling between the grabber device <NUM> and the charge station can be provided by any number of charge points in any arrangement.

The charge point <NUM> or charge receiving pad <NUM> may be in the form of a charge contact and may be sprung based so as to lessen the impact of the power transfer unit making contact with a charge providing pad on the top surface of the charge station. Two or more of the charge receiving pads <NUM> electrically couple to two or more of the lifting bands <NUM> supporting the grabber device <NUM>, e.g. use of a bracket comprising a terminal block. In an alternative embodiment of the present invention, two or more dedicated electrical cables can electrically couple the charge receiving pads <NUM> of the grabber device <NUM> to the battery in the body of the load handling device <NUM> instead of the use of the lifting tethers <NUM>. Additional charge contacts on the grabber device can be present to electrically couple with two other charge providing pads on the charge station to supress arcing between the contact surfaces between the grabber device and the charge station.

The motors used to drive the wheels and the lifting drive assembly are commonly based on DC (direct current) motors, mainly because they are easier and cheaper to control than AC motors and have higher starting torque and have a quick starting and stopping ability. However, as a result of powering the motors by DC, switches used to connect the motors to a DC power source which can carry a current in the region of <NUM> amps are susceptible to arcing. To mitigate excessive arcing between the contact surfaces of the charging receiving pads and the charge providing pads on the top surface of the charge station, additional charge contacts may be present to establish that an initial electrical connection has been made with the charge head of the charge station before full flow of around <NUM> amps to charge the battery is transferred through the contact pads. An initial low current level having a limit below which any extensive arcing does not occur is supplied to the additional charge receiving pads <NUM> of the grabber device <NUM>. Once electrical connection is established and an adequate contact pressure is established between the contact pads (charge receiving pads and charge providing pads), large currents can then be allowed to flow through the charge providing pads. Various other arc suppressing devices commonly known in the art including but are not limited to solid state relays, capacitors, snubbers etc., are permissible in the present invention.

A bracket <NUM> comprising one or more electrical terminal blocks can be used to connect the end <NUM>, e.g. second end, of the lifting tether or band <NUM> to the grabber device <NUM> (see <FIG>), e.g. via a set of wires. The first end <NUM> of the lifting tether <NUM> is wound on a spool or reel <NUM> mounted on drive shafts <NUM> in the body of the load handling device and driven by one or more motors <NUM>. One or more of the brackets <NUM> used for fixing the grabber device <NUM> to the lifting tether <NUM> may be used to electrically couple the charge point <NUM> to the battery via a set of wires or alternatively, if a dedicated electrical cable is used to transfer power to the battery, a separate bracket (not shown) can be used to electrically couple two or more dedicated electrical cables to the battery (one wire providing DC- and the other wire providing DC+). The bracket is made electrically insulating to electrically isolate the bracket from the other components of the grabber device <NUM>. As shown in <FIG>, the bracket may comprise one or more electrically insulating terminal blocks to electrically couple the charge contacts or the charge receiving elements with at least two of the lifting tethers or dedicated electrical cables for charging the battery.

The spool or reel <NUM> carrying the electrical cable or band, be it two or more of the lifting tethers <NUM> or a dedicated electrical cable, are provided with two or more electrical contacts to transfer power from the charge station to the battery via the spool or reel. In the particular example shown in <FIG>, the reel or spool <NUM> carrying the electrical cable or lifting tether <NUM> comprises a slip ring <NUM> for electrically coupling to two or more conducting brushes. Slip rings <NUM> are often made of electrically conductive materials, such as copper and fitted to the shaft <NUM> of the drive motor <NUM> with connective wiring going into the motors from them. The component which transmits the energy to the slip ring is called a 'brush' and commonly made with a mixture of carbon and copper and constantly touches the slip-rings, hence the name 'brush' as they constantly brush against the slip-rings. This constant touch conveys the current along the two or more of the lifting tethers <NUM> to charge the battery. Other cord reel technology commonly known in the art to electrically couple the battery to the electrical cable or lifting tether, be it the lifting tether or dedicated electrical cable, wound on the spool or wheel are permissible in the present invention.

In an alternative embodiment of the present invention, electrical connection between the battery and the electrical cable, be it the lifting tether or a dedicated electrical cable, can use a pantograph type mechanism (not shown) comprising an electrical contact strip or shoe to electrically contact the electrical cable or lifting tether <NUM> whenever the battery is being charged. The pantograph may be spring-loaded and pushes a contact shoe up against the electrical cable to transfer current from the electrical cable or lifting tether to the battery. A sensor such as a depth sensor (not shown) may be used by the controller to instruct the pantograph to engage with the electrical cable. Various arc suppressing devices commonly known in the art including but are not limited to solid state relays, capacitors, snubbers etc., can be used to prevent arcing between the contact shoe and the lifting tether or electrical cable. Once the battery is charged as determined by a control, electrical connection to the battery is removed by disengaging the electrical contact between bush and the slip ring or between the shoe of the pantograph and the electrical cable. As discussed above, one or more additional contact pads can be mounted to the charge station that is arranged to electrically couple with one or more contact pad mounted to the charge station. In the particular embodiment shown in <FIG>, the charge station <NUM> comprises four contacts pads <NUM>; two of which are used to transfer power to the battery and the other two can be used to send signals to and from the grabber device <NUM>, i.e. check the status of the battery. A control system will, thus, ensure that the charge providing pads supply the required current based on the condition of the rechargeable battery. The condition may be based on at least one of voltage, temperature, state of charge, depth of discharge, and current, i.e. whether fully charged.

The charge receiving pads <NUM> mounted to the grabber device <NUM> electrically couple with the contact providing pads of a charge station <NUM> as the grabber device <NUM> is drawn towards the charge station <NUM>. In the particular example of the present invention shown in <FIG>, the charge station <NUM> comprises corresponding locking features <NUM> that mirror the locking features <NUM> in the container, discussed above, for engaging with the gripper elements <NUM> mounted to the underside of the grabber device <NUM>. To properly align the gripper elements <NUM> with the corresponding locking features <NUM> in the charge head of the charge station <NUM>, as with the engagement features of a container discussed above, the charge station <NUM> further comprises cut-outs or holes <NUM> (see <FIG>) that are receivable by at least one locating pin <NUM> of the grabber device <NUM>. The locating pins <NUM> also help to align the charge providing pads <NUM> of the charge head into contact with the charge receiving pads of the grabber device <NUM>.

<FIG> shows an example of the present invention where the grabber device <NUM> engages with the charge station <NUM> of the storage system of the present invention. The charge contacts or the charge receiving pads <NUM> are drawn towards the charge providing pads <NUM> of the charge station <NUM> with sufficient force or pressure to minimise the electrical contact resistance between their corresponding contact surfaces. Each or both of the charge contacts and the contact pads <NUM>, <NUM> can be resiliently biased in a vertical direction towards each other to increase the contact force between their corresponding contact surfaces.

In a particular embodiment of the present invention, the corresponding locking features <NUM> of the charge station <NUM> comprise holes or apertures for receiving the gripper elements <NUM> of the grabber device <NUM>. As shown in <FIG>, the charge station <NUM> comprises a raised platform <NUM> having corresponding locking features <NUM> to engage with the gripper elements <NUM> mounted to the underside of the grabber device <NUM>. In addition to the locking features <NUM>, the top surface of the platform <NUM> comprises a charge head comprising two or more contact providing pads <NUM> that electrically couple with the charge receiving pads <NUM> of the grabber device <NUM>. Electrical connection between the charge head of the charge station <NUM> and the grabber device <NUM> can be via a plug and socket type connection, e.g. plug-in systems from Staubli® or a floating type connection. With floating type connection, power is transferred by induction power transfer and therefore, does not require any physical contact between the charge pads of the grabber device <NUM> and the charge head (charge providing pads) of the charge station <NUM>. Equally but not exclusively the gripper elements <NUM> mounted to the grabber device <NUM> can be used to transfer power from the charge station <NUM> to the battery via a suitable electrical cable. The charge head comprising the charge providing pads <NUM> of the charge station <NUM> may have suitable electrical contacts to electrically engage with the gripper elements <NUM>. Auxiliary components of the charge station <NUM> such as the rectifier can be mounted to the charge station <NUM>, e.g. mounted to the underside of the raised platform <NUM>.

The charge station <NUM> has a footprint that is sized to fit inside the grid space of the grid framework structure shown in <FIG> and <FIG>; more specifically the charge station <NUM> has a footprint that is substantially the same size as a container <NUM> used to store product lines. In use, when charging the battery, the load handling device <NUM> traverses and positions itself over a grid space occupied by the charge station <NUM> of the storage system of the present invention. Once positioned over a grid space occupying the charge station <NUM> of the storage system of the present invention, the load handling device <NUM> in response from a signal from a controller lowers the grabber device <NUM> suspended from lifting tethers <NUM> vertically into the grid space to engage with the charge head (charge providing pads <NUM>) of the charge station <NUM>. Engaging the grabber device <NUM> of the present invention with the charge station <NUM> is demonstrated in <FIG> and <FIG> of the present application showing the grabber device <NUM> approaching into engagement with the charge station <NUM>.

Although <FIG> illustrates a load handling device occupying a single grid space where the container receiving space is a recess inside the vehicle body, the invention also encompasses a load handling device including a cantilever as part of the vehicle body, where the container receiving space is located below the cantilever arm.

Charging may be controlled by a control system commonly known in the art whereby the control system will ensure that the charge pads or the charge providing elements of the charge station supply the required current based on the condition of the rechargeable power source. The condition may be based on at least one or voltage, temperature, state of charge, depth of discharge, state of health and current as discussed above. A charging signal may be transferred through the grabber device <NUM> from the charge station <NUM> via one or more signal transfer pads or elements that are contactable when the grabber device mates with the charge station. Alternatively, required signalling between the rechargeable power source and the charge station may also be performed by suitable wireless transfer. The control system may cause the grabber device to disengage from the charge head in response to a condition of the rechargeable power source. For example, the control system actuates the gripper elements <NUM> to disengage from the charge head in response to a signal from the rechargeable power source indicating that the rechargeable power source has reached a predetermined depth of charge. In an event that the rechargeable power source reaches a predetermined temperature that would be a potential fire hazard, the control system instructs the grabber device to disengage from the charge head.

In operation, the gripper elements <NUM> of the grabber device <NUM> engage with the corresponding locking features <NUM> formed in the platform <NUM> of the charge station <NUM>. As the gripper elements <NUM> are actuated to engage with the locking features <NUM> in the platform <NUM> of the charge station <NUM>, the charge receiving pads <NUM> mounted to the underside of the grabber device <NUM> are drawn towards two or more charge providing pads <NUM> on the top surface of the platform <NUM> and thereby, establishes electrical contact. Electricity is then transferred from the charge station <NUM> via two or more electrical cables or lifting tethers <NUM> to the battery located in the body of the load handling device <NUM>. As the current travelling through the electrical cables or lifting tethers can be in the order of <NUM> - <NUM> amps, various arc suppressing devices commonly known in the art including but not limited to solid state relays, capacitors, snubbers etc., can be used to prevent arcing at the point of electrical connection. The locking features <NUM> in the platform <NUM> are sized so that the charge receiving pads mounted to the grabber device are drawn towards the charge providing pads of the charge head with sufficient contact pressure when the gripper elements are actuated to maximise the contact surface area and thereby, minimise the electrical contact resistance between the contacts. In the particular embodiment shown in <FIG>, the depth of the holes forming the locking features <NUM> are sized to draw the charge receiving pads with the charge providing pads with sufficient contact pressure to maximise contact surface area.

Charging of the rechargeable power source may be controlled by a suitable control system known in the art. The control system will ensure that the charge providing pads supply the required current based on the condition of the rechargeable power source, e.g. temperature, voltage, state of charge and current. The grabber device <NUM> can comprise additional contact pads that cooperate with corresponding contact pads of the charge station to feed signals on the status or the condition of the rechargeable power source to a controller. <FIG> is a block diagram depicting an example of the charge control system of a storage system according to the present invention.

When docked at the charging station, information about the health and status of the rechargeable power source <NUM>, e.g. battery, is fed to a controller <NUM>. Status of the rechargeable power source is input into the controller <NUM>. When sufficient charge has been transferred to the rechargeable power source or when the rechargeable power source is fully charged, the controller <NUM> actuates the gripper elements <NUM> to release the grabber device <NUM> from the charge station <NUM> and subsequently, instructs the lifting device to raise the grabber device <NUM> away from the charge station <NUM>.

When charging is completed, the grabber device <NUM> disengages from the charge station <NUM> by collapsing the gripper elements <NUM> to release itself from the locking features <NUM> in the platform <NUM> of the charging station <NUM> and thereby, break electrical contact between the charge point <NUM> of the grabber device <NUM> and the contact providing pads <NUM> of the charge station <NUM>, whereupon the lifting device is able to raise the grabber device <NUM>. Where the load handling device houses the container receiving space within the vehicle body, the lifting device raises the grabber device into the body of the load handling device <NUM>, i.e. within the container receiving space <NUM> of the load handling device <NUM>. Where the vehicle body of the load handling device includes a cantilever with the container receiving space positioned below the cantilever, the lifting device raises the grabber device up to the container receiving space below the cantilever. As discussed above, the grabber device disengages from the charge station <NUM> in response to a signal from the controller <NUM>, i.e. the signal indicating that the rechargeable power source has reached a predetermined depth of charge. To prevent arcing between the contact pads when the grabber device disengages from the charge station <NUM>, the controller switches off the power (current) being supplied to the rechargeable power source, e.g. by terminating the power at the charge station or at least reduces the current to a small or minimal value that does not present any arcing prior to the grabber device disengaging from the charge head. For example, the controller <NUM> switches the current off at the power source charger <NUM> in response to sufficient current being supplied to the rechargeable power source or when the rechargeable power source has reached a predetermined charge. Equally, the rechargeable power source automatically disconnects from the power source charger <NUM> once the power stored in the rechargeable power source has reached a predetermined value. Thus, when the contact pads of the grabber device and the charge station are disconnected, there is no or little arcing when the contact pads separate. One or more contact pads between the grabber device <NUM> and the charge head of the charge station <NUM> can be used to monitor the status of the rechargeable power source during charging and send the signal to the controller. Equally or additionally, additional contact pads may be present on the grabber device <NUM> to electrically couple with additional contact pads on the charge station to prevent or at least suppress arcing between the charge providing pads and charge receiving pads.

Claim 1:
A load handling device (<NUM>) for lifting and moving containers (<NUM>) stacked in a storage system (<NUM>) comprising a grid framework structure (<NUM>) supporting a pathway arranged in a grid pattern above the stacks (<NUM>) of containers(<NUM>), the load handling device (<NUM>) comprising:
a vehicle body (<NUM>) housing a driving mechanism (<NUM>) operatively arranged for moving the load handling device (<NUM>) on the grid framework structure (<NUM>); said driving mechanism (<NUM>) is powered by a rechargeable power source (<NUM>) electrically coupled to an electrical charge point (<NUM>) for electrically coupling with a charge head (<NUM>) of a charge station (<NUM>) in use,
a lifting device comprising a lifting drive assembly and a grabber device (<NUM>) configured, in use, to releasably grip a container (<NUM>) and lift the container (<NUM>) from the stack (<NUM>) into a container-receiving space (<NUM>);
characterised in that;
the lifting device comprises the electrical charge point (<NUM>) such that in use charging of the rechargeable power source (<NUM>) occurs by the lifting device engaging with the charge head (<NUM>) of the charge station (<NUM>).