Apparatus and Method for Charging a Load Handling Device

Abstract

A load handling device for lifting and moving containers stacked in a storage system a grid framework structure, the load handling device including: a vehicle body housing a driving mechanism operatively arranged for moving the load handling device on the grid framework structure; a lifting device having a lifting drive assembly and a grabber device configured to releasably grip a container and lift the container from the stack into a container-receiving space; are chargeable power source electrically coupled to an electrical charge point for electrically coupling to a charge head of a charge station wherein; the electrical charge point includes a charge collector connectable to the charge head of the charge station under action of a magnet.

Claims

1. A load handling device for lifting and moving containers stacked in a storage system with a grid framework structure containing a pathway arranged in a grid pattern above the stacks of containers, the load handling device comprising: a vehicle body housing a driving mechanism operatively arranged for moving the load handling device on the grid framework structure; and a lifting device having a lifting drive assembly and a grabber device configured to, in use, releasably grip a container and lift the container from the stack into a container-receiving space, said driving mechanism and the lifting drive assembly being powered by a rechargeable power source electrically coupled to an electrical charge point arranged on the vehicle body for electrically coupling to a charge head of a charge station in use; wherein: the electrical charge point includes a charge collector connectable to the charge head of the charge station under action of a magnet.

2. The load handling device of claim 1, wherein the charge collector is configured to be connectable to the charge head of the charge station under action of an electromagnet.

3. The load handling device of claim 1, wherein the charge collector is configured to be moveable relative to the vehicle body for connecting to the charge head of the charge station under action of the magnet.

4. The load handling device of claim 3, wherein the charge collector comprises: one or more magnets.

5. The load handling device of claim 4, wherein the one or more magnets are rare-earth magnets.

6. The load handling device of claim 5, wherein the one or more rare-earth magnets are neodymium magnet.

7. The load handling device of claim 1, wherein the charge collector is configured to be extendible from or retractable within an outer housing.

8. The load handling device of claim 1, wherein the electrical charge point is mounted to an exterior surface at least one wall of the vehicle body.

9. The load handling device of claim 8, wherein the wall is a sidewall of the vehicle body.

10. The load handling device of claim 1, wherein the vehicle body comprises: a skirt having a first pair of opposite side walls and a second pair of opposite side walls, wherein the electrical charge point is mounted to a bottom edge of at least one of the first and/or second pair of opposite sidewalls.

11. The load handling device of claim 1, wherein the charge collector comprises: at least two charge-receiving pads arranged to be connectable to at least two charge-providing pads of the charge head.

12. A storage system comprising: i) a grid framework structure supporting a pathway arranged in a grid pattern having a plurality of grid spaces or grid cells; ii) a load handling device configured for lifting and moving containers stacked in the grid framework structure, the load handling device including: a) a vehicle body housing a driving mechanism operatively arranged for moving the load handling device on the grid framework structure; b) a lifting device having a lifting drive assembly and a grabber device configured to, in use, releasably grip a container and lift the container from the stack into a container-receiving space; said driving mechanism and the lifting drive assembly being powered by a rechargeable power source electrically coupled to an electrical charge point arranged on the vehicle body having a charge collector; and iii) a charge station including a charge head electrically coupled to a power source charger; wherein: the charge head is configured to be connectable with the charge collector to charge the rechargeable power source of the load handling device under action of a magnet.

13. The storage system of claim 12, wherein the charge collector comprises: at least two charge-receiving contact pads arranged to be connectable to at least two charge-providing contact pads of the charge head.

14. The storage system of claim 12, wherein the charge collector and/or the charge head is/are configured to be moveable to electrically couple with each other under action of the magnet.

15. The storage system of claim 14, wherein the charge collector and/or the charge head is configured to be extendable from or retractable within an outer housing.

16. The storage system of claim 12, wherein the charge collector and the charge head of the charge station are arranged to electrically couple with each other under action of a magnetic attractive force and electrically disconnect from each other under action of a magnetic repulsive force.

17. The storage system of claim 16, wherein the charge collector and the charge head each comprise: one or more magnets.

18. The storage system of claim 17, wherein the one or more of the magnets of the charge collector or the charge head comprises: a rare-earth magnet.

19. The storage system of claim 12, wherein the charge head is mounted to the pathway.

20. The storage system of claim 19, wherein the charge head is mounted to an arm that is configured to be moveable to electrically couple with the charge collector of the load handling device.

21. The storage system of claim 20, wherein the arm is configured to be moveable in response to a signal from a controller.

22. The storage system of claim 12, wherein the electrical charge point is mounted to an exterior surface at least one wall of the vehicle body.

23. The storage system of claim 22, wherein the wall is a sidewall of the vehicle body.

24. The storage system of claim 12, wherein the vehicle body comprises: a skirt having a first pair of opposite side walls and a second pair of opposite side walls, wherein the electrical charge point is mounted to a bottom edge of at least one of the first and/or second pair of opposite sidewalls.

25. The storage system of claim 12, wherein the charge head is configured to be connectable to the charge collector to charge the rechargeable power source of the load handling device under action of an electromagnet.

26. The storage system of claim 25, wherein the electromagnet will be activated when the charge-providing pads of the charge head are in contact with the charge-receiving pads of the charge collector.

27. The storage system of claim 26, wherein the electromagnet is activated by an actuator.

28. The storage system of claim 27, wherein the actuator is a contact switch.

29. The storage system of claim 25, comprising: a controller configured to be operable to supply current to charge the rechargeable power source in response to the electromagnet being activated.

30. The storage system of claim 25, wherein the charge head is configured and arranged to be moveable among a first position wherein the charge head will be spaced apart from the charge collector and a second position wherein the charge head will be in physical contact with the charge collector.

31. The storage system of claim 30, wherein the charge head is guided in a vertical direction by at least one guide member.

32. The storage system of claim 30, wherein the charge head is moveable to the second position under action of gravity to contact the charge collector.

33. The storage system of claim 30, wherein the charge head is configured and arranged to be raised to the first position by a linear actuator to disengage the charge head from the charge collector of the load handling device.

34. The storage system of claim 33, wherein the electromagnet is-will be activated when the linear actuator has extended a predetermined length.

35. A method of charging a rechargeable power source of a load handling device in a storage system, the load handling device including a vehicle body housing a driving mechanism operatively arranged for moving the load handling device on the grid framework structure; and a lifting device having a lifting drive assembly and a grabber device configured, in use, to releasably grip a container and lift the container from the stack into a container-receiving space, said driving mechanism and the lifting drive assembly being powered by a rechargeable power source electrically coupled to an electrical charge point arranged on the vehicle body for electrically coupling to a charge head of a charge station in use, wherein the electrical charge point includes a charge collector connectable to the charge head of the charge station under action of a magnet, the method comprising steps in the order of: a) lowering the charge head towards the charge collector of the electrical charge point; b) activating an electromagnet to pull and/or push the charge head towards the charge collector under a magnetic attractive force; and c) supplying current to the rechargeable power source via the charge head.

36. The method of claim 34, comprising: d) activating the electromagnet in response to detecting a signal from an actuator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] 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:

[0060] FIG. 1 is a schematic diagram of a grid framework structure according to a known system,

[0061] FIG. 2 is a schematic diagram of a top down view showing a stack of bins arranged within the grid framework structure of FIG. 1.

[0062] FIG. 3 is a schematic diagram of a system of a known load handling device operating on the grid framework structure.

[0063] FIG. 4 is a schematic perspective view of the load handling device showing the lifting device gripping a container from above.

[0064] FIGS. 5(a) and 5(b) are schematic perspective cut away views of the load handling device of FIG. 4 showing (a) the container receiving space of the load handling device and (b) a container accommodated within the container receiving space of the load handling device.

[0065] FIG. 6 is a schematic diagram showing a known charging station comprising a charge unit suspended from a support structure.

[0066] FIG. 7a is a schematic diagram from above of a known charge unit or charge head showing a plurality of profiled sections.

[0067] FIG. 7b is a schematic diagram from below of the known charge unit or charge head showing a power transfer unit.

[0068] FIG. 8 is a schematic view of a top surface of a known load handling device.

[0069] FIG. 9 is a schematic perspective view of the charge contact system showing the charge collector mating with the charge head according to a first embodiment of the present invention.

[0070] FIG. 10 is a schematic perspective view of the charge contact system showing disconnection of the charging system according to the first embodiment of the present invention.

[0071] FIG. 11 is a schematic perspective view of a side view of the load handling device docked at a charging station in one arrangement according to the first embodiment of the present invention.

[0072] FIG. 12 is a schematic perspective view of a side view of the load handling device docked at a charging station in a second arrangement according to the first embodiment of the present invention.

[0073] FIG. 13 is a schematic perspective view of a side view of the load handling device docked at a charging station in a third arrangement according to the first embodiment of the present invention.

[0074] FIG. 14 is a schematic perspective view of the charging head engaged with the charge collector on the load handling device according to a second embodiment of the present invention.

[0075] FIG. 15 is a perspective side view of the charge head disengaged from the charge collector on the load handling device according to the second embodiment of the present invention.

[0076] FIG. 16 is a schematic perspective side view of the charge head engaged with the charge collector on the load handling device according to the second embodiment of the present invention.

[0077] FIG. 17 is a block diagram depicting an example of the charge control system according to the second embodiment of the present invention.

DETAILED DESCRIPTION

[0078] It is against the known features of the storage system, such as the grid framework structure and the load handling device described above with reference to FIGS. 1 to 6, that the present invention has been devised.

[0079] FIGS. 9 and 10 respectively show the docking and disconnection of a charge contact system according to a first embodiment of the present invention. The charge contact system comprises an electrical charge point 80 which is arranged on the vehicle body of the load handling device and a charge head 84 forming a charge station 82. The charge contact system according to the present invention utilises a charge system commercially available from RoboteQ® having a head office in 7812 E. Acoma Dr. Suite 1, Scottsdale Ariz. 85260, USA. The electrical charge point 80 comprises a charge collector 86 comprising at least two charge receiving pads 88 which are arranged to cooperate with at least two charging providing pads 90 of the charge head 84. Power is supplied to the charge head 84 by a suitable power source charger (not shown). In the particular embodiment of the present invention, the two charge providing pads provide a direct current, i.e. one of the charge-providing pads 90 is DC and the other is DC+. The charge collector 86 is arranged to be moveable relative to the vehicle body of the load handling device. In the particular embodiment of the present invention, the charge collector 86 is extendable from and retractable within an outer housing 92. More specifically, the charge receiving pads 88 are mounted to an inner housing which is moveable within the outer housing 92 in a telescopic manner. FIG. 9 shows the charge collector 86 in both a retracted configuration and an extended configuration.

[0080] Whilst the container receiving space 40 for accommodating a container when it is lifted by the crane mechanism is arranged within the vehicle body 32 shown in FIG. 5, the present invention is not limited to the container receive space 40 being located within the vehicle body 32. 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 WO2019/238702 (Autostore Technology AS). 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.

[0081] The outer housing 92 of the electrical charge point 80 is mounted to the vehicle body of the load handling device so as to allow the charge collector to be moveable relative to the vehicle body. Any means to mount the outer housing 92 to the vehicle body is applicable in the present invention, e.g. use of bolt, screw or adhesive etc. The charge collector 86 comprises one or more magnets (not shown) that are arranged to be attracted to one or more magnets (not shown) in the charge head 84 when the charge collector 86 is positioned over the charge head 84, i.e. unlike poles of the respective one or more magnets in both the charge collector 86 and the charge head align. The magnetic attractive force causes the charge receiving pads 88 of the charge collector 86 to move towards and physically contact the charge providing pads 90 of the charge head 84. This is demonstrated by the arrow shown in FIG. 9. The one or more magnets are permanents magnets, preferably rare earth magnets. The use of rare earth magnets provides the necessary pulling force to physically clamp the charge receiving pads of the charge collector against the charge providing pads of the charge head with sufficient force to prevent arcing and lower the contact resistance. Typically, a clamping force of 40N is required to prevent arcing and lower the contact resistance. Examples of rare earth magnets include but are not limited to neodymium magnets and samarium cobalt magnets.

[0082] Disconnection of the charge collector 86 from the charge head 84 involves moving the charge collector 86 to cause the one or more magnets in the charge collector 86 to repel one or more magnets in the charge head 84. Optionally, the charge head 84 comprises two or more sets of magnets, each set comprising at least one magnet that are positioned side by side. A first set of magnets in the charge head is arranged to magnetically attract the one or more magnets in the charge collector 86. A second set of magnets in the charge head is arranged to magnetically repel the one or more magnets in the charge collector. The reverse is equally applicable where the charge collector 86 comprises two or more sets of magnets that is arranged to magnetically attract and/or repel the one or more magnets in the charge head. In use, the charge collector mounted to the load handling device is moved along the charge head 84 so that like poles of one or more magnets in both the charge collector 86 and the charge head 84 align. The strong repulsive force experienced by the charge collector causes an instant retraction of the charge collector 86 within the outer housing 92 and is therefore, raised clear of the charge head 84 for the load handling device to continue on its course along the track. This is demonstrated by the push arrow shown in FIG. 10. The alignment of the charge collector with the charge head can take the form of the load handling device positioning itself against the charge station. Thus, in a first position of the load handling device relative to the charge station, the charge collector 86 extends to contact the charge head 84 and in a second position of the load handling device relative to the charge station, the charge collector 86 retracts and disconnects from the charge head 84.

[0083] The charge collector 86 can be held in its retracted configuration by magnetic attractive forces of the one or more magnets in the charge collector 86. To allow the charge collector 86 to be drawn towards the charge head 84, strong rare earth magnets are located in the charge head 84 which overcomes the magnetic attractive forces holding the charge collector 86 in its retracted configuration. By controlling the strength of the magnets in the charge head 84 and the charge collector 86, the charge collector 86 can be held in its retracted configuration to safely traverse along the rail or tracks on the grid framework structure and when docked at the charge station, the strong magnetic attractive forces of the one or more magnets in the charge head 84 overcomes the magnet attractive forces holding the charge collector 86 in its retracted configuration to cause the charge collector 86 to move and be drawn towards the charge head 84. In an alternative arrangement, the charge collector is held (or biased) in its retracted configuration within the outer housing 92 by a resilient member, e.g. by use of a spring, and is only drawn towards the charge head by the magnetic attractive forces generated between the charge head and the charge collector overcoming the biasing force. This removes the need to have a separate set of magnets to retract the charge collector into its outer housing.

[0084] Whilst the particular embodiment shown in FIGS. 9 and 10, describes the charge collector 86 to be moveable relative to the charge head 84, the reverse is equally applicable where the charge collector 86 is fixed and the charge head 84 is moveable towards the charge collector 86 during a charging operation. This removes the need for the charge collector 86 to be retracted (e.g. raised) in order to provide clearance for the load handling device to travel along the rails as the charge receiving pads 88 of the charge collector 86 may be made substantially flush with the surface of at least one wall of the vehicle body or at least slightly proud of the surface of at least one wall of the vehicle body but sufficiently clear to not present an obstacle when travelling on the rails. During a charging operation, when the load handling device is docked at the charging station, the charge head 84 is moveable to extend towards the charge collector 86 under a strong attractive magnetic force as a result of the one or more magnets in the charge collector 86 and the charge head 84. Whilst it is beneficial that the charge head 84 disconnects from the charge collector by retracting within its outer housing by magnetic repulsive forces, it is not an essential operation since the charge head 84 does not present itself as an obstacle as it is always in a fixed location. Movement of the load handling device can cause disconnection of the charge collector from the charge head. However, movement of either the charge collector 86 or the charge head 84 towards each other helps to mitigate potential alignment problems between the contact surfaces of the charge receiving pads 88 of the charge collector 86 and the charge providing pads 90 of the charge head 84. Equally, movement of either the charge collector 86 and/or the charge head 84 towards each other also helps to accommodate height differences of load handling devices.

[0085] The charge contact system according to the present invention shown in FIGS. 9 and 10 can be mounted to different areas of the vehicle body, thereby providing different charging regimes. FIGS. 11 to 13 shows the different charging regimes according to the present invention. FIG. 11 is an example where the moveable part of the charge contact system of the present invention representing the charge head is drawn towards the charge collector fixed to a top wall 94 of the load handling device. The electrical charge point 80 shown in FIG. 11 is arranged on the exterior surface of a top wall 94 of the vehicle body 32. This allows for the charge head 84 of the present invention to be retrofitted to an existing charge station having an L shaped framework 50 discussed above in the introductory part of the patent specification. The charge head 84 is suspended from the L shaped framework 50 and positioned to cooperate with the charge collector 86 mounted to the top wall 94 of the vehicle body 32 when the load handling device 30 is docked underneath the charge head 84 of the charge station 82.

[0086] In another charging arrangement, the electrical charge point 80 is arranged to one of the side walls 96 of the vehicle body 32 as shown in FIG. 12. In this configuration, charging occurs by the load handling device 30 laterally docking onto the charge station 82 in a sideways direction as indicated by the arrow shown in FIG. 12. This removes the need to have a dedicated framework to suspend the charge head over the load handling device as shown in FIG. 11 as the charge head 84 can be mounted to a side wall proximate the grid framework structure or a crash barrier that has been retrofitted to accommodate a charge station. Analogous to the arrangement shown in FIG. 11, the charge collector 86 can be made to be moveable relative to the vehicle body 32, i.e. the charge contact system of the present invention can be orientated so that the charge collector 86 is moveable to be drawn towards the charge head 84, which remains fixed, when docked at the charge station 82.

[0087] To remove clutter around the grid framework structure, the charge contact system of the present invention can be located at floor level of the grid framework structure. As shown in FIG. 13, the charge collector 86 can be mounted at the foot of the vehicle body 32, e.g. at the bottom edge of a skirt of the vehicle body 32. The vehicle body 32 housing the auxiliary components of the load handling device such as the drive motors comprises a skirt body comprising a first pair of opposite side walls 98 and a second pair of opposite side walls 100. The electrical charge point 80 is mounted to a bottom edge of at least one of the first and/or second pair opposite sidewalls 98, 100 that is arranged to cooperate with the charge head 84 mounted to a rail or track 102 on the grid framework structure. In this way, charging occurs when the load handling device 30 drives over and positions itself over a rail or track 102 comprising the charge head 84 mounted thereon to electrically couple with the electrical charge point 80, more specifically the charge collector 86. A moveable arm (not shown) can be used to correctly position the charge head 84 onto the charge collector 86 so that the corresponding charge providing pads 90 and charge receiving pads 88 properly align. The moveable arm can be a robotic arm having one end mounted to a track or grid within a grid cell and the charge head is mounted to the other end of the moveable arm. During a charging operation, the moveable arm is instructed by a controller to position the charge head 84 into engagement with the charge point 80 of the load handling device 30, more specifically the charge collector 86 so that either the charge head 84 or the charge collector 86 are drawn towards each other, depending which is the moveable component, by magnetic attraction. The moveable arm can be pivotally mounted to a grid structure or rail on the grid framework structure.

[0088] Whilst the embodiments shown in FIGS. 11, 12 and 13 show different arrangements of the charge contact system mounted to the vehicle body, the present invention is not limited to the orientations shown in FIGS. 11 to 13. The electrical charge point of the present invention can be mounted to other areas of the vehicle body. Additional charge contacts of the present invention can be incorporated into the system to monitor the status of the battery. Thus, instead of functioning as a charge collector, one or more additional contact pads can be mounted to the load handling device for cooperating with corresponding contact pads of the charge station for supplying information on the status of the battery. The contact pads can have the same functionality as the charge contact system of the present invention described above, in that one or more contact pads are extendable from and retractable within an outer housing under the influence of one or more magnets. A control system can 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 state of health. The charge collector 86 or the charge head can be retractable within the outer housing by either magnetic forces or a resilient member, e.g. a spring.

[0089] In alternative embodiment of the present invention, the magnetic attractive forces between the charge head and the charge collector can be generated by an electromagnet rather than the use of one or more permanent magnets. The advantage of the use of an electromagnet over the use of permanent magnets is that the electromagnet can be controlled to generate the necessary magnetic attractive forces to draw the charge head to mate or physically contact the charge collector, e.g. by controlling the current through a coil making up the electromagnet. Examples of an electromagnet is a solenoid wound around a magnetic core commonly known in the art. In this way, one or more actuators mounted to the charge station can be used to activate or actuate the electromagnet to provide the necessary magnetic attractive force to physically clamp the charge head against the charge collector. In the particular embodiment of the present invention shown in FIGS. 14 to 16, the charge contact system 104 comprises a charge station 101 comprising a charge head 184 mounted to a support platform 106 moveable in the downward direction from a first position where the charge head is spaced apart from the charge collector and a second position where the charge head is in physical contact with the collector. In the particular embodiment of the present invention, the charge head is configured to move from the first position to the second position under action of gravity. The charge head 184 is mounted to the bottom wall of the moveable platform 106 so as to cooperate with the electrical charge point 185 comprising the charge collector 186 when the charge head 184 is lowered onto the charge collector 186. The platform 106 is guided to move in a vertical direction by at least one guide member 108, e.g. a guide rod. The platform is freely moveable along the guide member 108 so as to permit the platform to drop in a vertical direction under its own weight, i.e. under gravity. Dampers commonly known in the art can be used to decelerate or dampen the fall of the platform along the at least one guide member and therefore, lessen the impact of the charge head with the charge collector, e.g. one or more springs or gas springs etc.

[0090] Mounted to the support platform 106 are one or more electromagnetics 116. The one or more electromagnets are arranged to magnetically attract the charge head 184 to the charge collector 186 mounted to a top wall of the vehicle body 32 when the one or more electromagnets 116 are activated or actuated, i.e. when current though the coils of the electromagnet are switched on. In the particular embodiment of the present invention, the one or more electromagnets 116 is/are positioned to at least one edge of the platform so as to distribute the clamping force across the platform when the electromagnets are activated or actuated and therefore, across the contact pads 188, 190 of the charge head 84 and the charge collector 86.

[0091] To disconnect the charge head 184 from the charge collector 186, e.g. once a charging operation has been completed, the platform 106 is raised clear of the charge collector 186. In the particular embodiment of the present invention, the platform 106 is raised by a linear actuator 110. As shown in FIGS. 14 to 16, the linear actuator 110 comprises a shaft 112. The foot or end of the shaft 112 comprise a stop 114 that is arranged to contact or butt up against a bottom wall or underside of the platform 106 as the linear actuator moves in an upward direction to raise the platform 106. Various linear actuators commonly known in the art to lift the platform include but are not limited to mechanical actuators, hydraulic actuators, pneumatic actuators, piezoelectric actuators, or electro-mechanical actuators are applicable in the present invention.

[0092] The charge collector 186 comprising the charge-receiving pads comprises a ferromagnetic material, e.g. iron, that is able to magnetically attract to the charge head 184 when the one or more electromagnets are activated or actuated. The one or more electromagnets 116 are activated or actuated in response to a signal from an actuator. In the particular embodiment of the present invention, the actuator is a contact switch 118 that breaks a circuit when the charge head 184 comes into contact with the charge collector 186 to cause the electromagnet to be activated or actuated. For example, the contact switch is formed of two parts that separate to break an electrical circuit and come together to complete the electrical circuit when the charge head disconnects from the charge collector. As shown in FIG. 15, one part of the contact switch 118 is mounted to the platform 106 supporting the one or more of the electromagnetics and the other part is mounted to a linear actuator 112. When the charge head 184 is spaced apart or separated from the charge collector 186 as demonstrated by the schematic view in FIG. 15, the contact switch 118 is closed (i.e. in contact). Conversely, when the charge head 184 comes into contact with or approaches the charge collector 186, e.g. when their corresponding pads contact, the contact switch 118 is open causing a break in the circuit as demonstrated by the schematic view in FIG. 16. The break in the circuit is an indication that the charge head 184 is in contact with the charge collector 186 and causes the electromagnet to be activated or actuated via a suitable controller. The actuator to activate or actuate the electromagnet 116 is not limited to a contact switch and any type of actuator to provide a signal indicative that the charge pads of the charge head 184 is in physical contact with corresponding charge pads of the charge collector 186 and vice versa is applicable in the present invention. For example, one or more sensors, e.g. depth sensors, can be used to provide an indication that the charge head is in contact with corresponding charge pads of the charge collector. Similarly, the length of travel of the linear actuator 110 can be used to determine when the charge head 184 is in contact with corresponding charge pads of the charge collector 186.

[0093] The signal from the actuator 118 can be used by a controller to activate or actuate the electromagnet 116 and subsequently control the charging operation. One or more additional contact pads can be mounted to the charge head 184 or the platform 106 supporting the charge head to monitor the status of the rechargeable power source, i.e. to ensure that the charge head supplies the required current based on the condition of the rechargeable power source. As shown in the block diagram in FIG. 17, signals from the actuator 118 are input into a controller 120 and depending on the input signal from the actuator, the controller will activate or actuate the electromagnet to draw the charge head 184 towards the charge collector 186 so that an adequate contact pressure is established between the charge head and the charge collector and subsequently, transfer power from a power source charge (not shown) to charge the rechargeable power source. The charge head and/or the charge collector can be resiliently mounted and biased in the outward direction, e.g. sprung based, to lessen the impact between their respective contact pads but most importantly to control the clamping force under the influence of a magnetic attractive force. In operation when charging a rechargeable power source, the load handling device 30 is instructed to dock at the charge station. For example, a signal is sent from the load handling device to the controller 120 that the load handling device is about to dock at the charge station. Once docked, as indicated by a signal from the load handling device, the controller 120 allows the linear actuator supporting the charge head 184 to lower. For example, a locking mechanism or a stop holding the linear actuator in the raised position is disabled. This allows the platform 106 supporting the charge head 184 to free fall under gravity guided by the guide rods 108 towards the charge collector 186 of the load handling device. As the platform lowers and the charge head 184 remains spaced apart from the charge collector, the actuator remains closed as shown in FIG. 15, i.e. the contact switch is closed. At the point, the charge head 184 contacts the charge collector 186 or their corresponding contact pads contact, the linear actuator 110 continues to drop to cause the contact switch to break or open as shown in FIG. 16. Breakage of the contact switch is an indication that the actuator has been actuated and a signal is sent to the controller 120 to indicate the same. When the actuator is actuated, the controller 120 starts a timer to allow the linear actuator 110 (more specifically the shaft of the linear actuator) to fall for a predetermined amount of time as shown in FIG. 16. The timer prevents the linear actuator crashing into the top wall of the load handling device since the linear actuator is only allowed to fall for a predetermined amount of time and to cause the actuator to be actuated—in the particular embodiment, a break in the contact switch. Alternatively or additionally, the controller can determine the length of travel of the linear actuator and can lower the linear actuator a predetermined length to prevent the linear actuator hitting the top of the load handling device.

[0094] Once the actuator has been actuated as determined by the break in the contact switch in the particular embodiment, the controller 120 activates or actuates the one or more electromagnets 116 mounted to the platform 106 supporting the charge head 184 to cause the charge-providing pads of the charge head 184 to be drawn towards the charge-receiving pads of the charge collector 186 by the pull strength of the electromagnetic attractive forces. The charge head 184 is mounted to a resilient member or is sprung loaded so as to compress by the pull strength of the magnetic attractive forces. The resilient member provides the charge head enough give to establish maximum surface area contact between the charge head 184 and the charge collector 186 and thereby, lower the contact resistance as well as to lessen the impact of the charge head 184 making contact with the charge pad of the charge collector 186. A clamping force of the order of 40 N can be established between the contact pads of the charge head 184 and the charge collector 186 necessary to prevent arcing between the contact pads and therefore, prevent degradation of the surface of the contact pads.

[0095] Subsequent to a clamping force being established between the charge head 184 and the charge collector 186, more specifically, their respective contact pads, the controller instructs a power transfer unit or power source charger (not shown) to transfer power to the rechargeable power source via the charge head 184. A delay can be built into the system to transfer power to the rechargeable power source once the one or more electromagnets have been activated or actuated. For example, a timer can be used to delay the transfer of power to the rechargeable power source once the electromagnet has been activated or actuated. Once a predetermined amount of time has elapsed as measured by the timer, the controller instructs the power transfer unit to transfer power to the rechargeable power source via the charge head 184. By incorporating a delay between activating the electromagnet and transferring power to the rechargeable power source helps to mitigate arcing so that once a relatively high contact force has been established between the contact pads, power is transferred through the charge head. The high contact pressure which can be in the order to 40N lowers the contact resistance between the charge head and the charge collector.

[0096] One or more additional contact pads (not shown) can be mounted to the platform supporting the charge head (mounted to the bottom wall of the platform), to monitor the status of the battery during charging and to ensure that the charge providing pads supply the required current based on the condition of the battery. Once the rechargeable power source is charged or receives the required amount of charge, the controller disconnects the charge head 184 from the charge collector 186. In the particular embodiment of the present invention as shown in FIGS. 14 to 16, the controller instructs the linear actuator 110 to raise and lift the charge head 184, more specifically the moveable platform 106 supporting the charge head 184 clear of the charge collector on the load handling device. Prior to disconnecting the charge head 184 from the charge collector 186, the electromagnets 116 are preferably switched off allowing the linear actuator 110 to freely lift the charge head 184 such that the contact pads of the charge head 184 breaks contact with the charge collector 186. Disconnection of the charge head 184 can, for example, occur once the controller detects that the rechargeable power source is in a charged state or in a fully charged state. In response to detecting that the rechargeable power source is in a fully charged state, the controller de-activates the electromagnet, i.e. switches the current off to the electromagnetic coils, allowing the linear actuator 110 to freely lift the charge head 184 away from the charge collector 186. This allows the linear actuator 110 to lift the charge head 184 mounted to the platform without being drawn to the charge collector 186 as a result of the electromagnetic pull. Disconnection is established when the contact switch re-connects to close the contact switch 118 as the linear actuator 110 is raised. Continuing lifting of the platform 106 raises the charge head 184 further away from the charge collector as shown in FIG. 15. At this point, the charge head 184 is spaced apart from the charge collector 186. Once the charge head is lifted clear of the charge collector, and the contact switch 118 has re-established connection, the load handling device is then free to move away from the charge station. As discussed above with respect to the activation or actuation of the electromagnet, a timer can be used to control the upward travel of the linear actuator and thus, the charge head once the actuator is closed, i.e. when the contact switch is closed.

[0097] The different operations of the charge contact system according to the second embodiment of the present invention can be summarised in the block diagram shown in FIG. 17. The input signal to the controller 120 is provided by the actuator to indicate the position of the charge head relative to the charge collector. The controller 120 controls the operation of the electromagnet 116 and power to the charge head. In response to a signal from the actuator, i.e. when the contact switch 118 is broken (see FIG. 16), the controller activates or actuates the electromagnet 116 by switching on the current through the solenoid making up the electromagnet. Strong magnetic attractive forces draw the charge head against the charge collector with sufficient pulling force to establish a maximum clamping force. Typically a clamping force of 40N or greater is necessary to prevent arcing and lower the contact resistance between the charge head and the charge collector. Once a sufficient clamping force is established by the pulling force of the electromagnet, the controller switches on the power transfer unit to transfer power to the rechargeable power source via the charge head.

[0098] When the rechargeable power source is fully charged, a signal is sent to the controller 120 to deactivate the electromagnet and the linear actuator 110 is actuated to lift the charge head 184 away from the charge collector 186. This causes the contact switch to re-establish connection. A timer can be used to control the lifting of the charge head 184 along the guide 108. For example, the timer can be started to add a predetermined delay once the contact switch 118 is closed so as to allow the charge head 184 mounted to the platform 106 to be lifted clear of the charge collector 186. Alternatively, the controller 120 can determine the length of travel of the charge head 184 along the guide 108 so that the controller 120 can instruct the linear actuator 110 to lift the charge head 184 a predetermined length. Once the contact switch 118 is closed, a signal is sent to the controller 120 indicating that the load handling device is free to move from the charge station.

[0099] Different combinations of features of the charge contact system in the first embodiment shown in FIGS. 9 and 10 and the second embodiment shown in FIGS. 14 to 16 can be used without departing from the scope of the present invention as defined in the claims. For example, one or more permanent magnets to pull the charge head into contact with the charge collector in the first embodiment of the present invention as shown in FIGS. 9 and 10 can be replaced by one or more electromagnets so as to allow a controller to activate/actuate the electromagnets as discussed in the second embodiment of the present invention to couple the change head into contact with the charge collector. In both embodiments of the present invention shown in FIGS. 9 and 10 and in FIGS. 14 to 16, the rechargeable power source is optionally housed within the vehicle body 32 (see FIGS. 4 and 5).