Method and system for sinking electrical energy from a motor

Abstract

A method and system for sinking electrical energy from a motor are disclosed. This method and system redirects the generated electrical energy from the motor to the sink.

Description

Technical Field

[0001] The present invention relates to a method and system for sinking energy from a motor as used in a load handling device.

Background Art

[0002] Some commercial and industrial activities require systems that enable the storage and retrieval of a number of different products. WO2015 / 185628A describes a storage and fulfillment system in which stacks of storage containers are arranged within a grid framework structure. The containers are accessed from above by a load handling device operating on rails or tracks located at the top of the grid framework structure. The load handling device is further described in WO2015 / 019055A1.

[0003] In a storage and fulfillment system, it is important for the load handling device to divert the energy generated by the motor in order to avoid components operating beyond their ratings. The present invention has been devised in view of such a background.

Summary of the Invention

[0004] In a first aspect, there is a system for dissipating energy generated by a motor, the system comprising: a first motor; a second motor; a controller; and the controller is configured to: drive the first motor; detect the electrical energy generated by the first motor; and divert the generated electrical energy to the second motor. This means that the second motor can sink the electrical energy generated by the first motor and prevent damage to the system. The second motor can also function as a heat sink.

[0005] The controller may be configured to use field-directed control or vector control to control the second motor to sink the generated electrical energy. This means that the sinking of the generated electrical energy can be precisely controlled.

[0006] The controller may be configured to use field-directed control or vector control to sink all of the electrical energy generated at the straight axis of the second motor. This means that the second motor does not generate torque when sinking the electrical energy generated by the first motor.

[0007] The system may include a busbar configured to supply power to a first motor and / or a second motor, wherein the controller is configured to monitor the voltage on the busbar to detect the energy generated by the first motor. This means that any potential damage to the system can be identified in advance.

[0008] The controller may be configured to divert the generated electrical energy to a second motor when the voltage on the busbar reaches a threshold. This means that any damage to the system and its circuits can be avoided.

[0009] The controller may be configured to divert the generated electrical energy until the busbar voltage falls below a threshold, or until the current limit of the second motor is reached, or until the temperature limit of the second motor is reached. This means that the system operates within safety limits.

[0010] The current setting point in the linear axis can be increased until the voltage on the busbar falls below a threshold, or until the current limit of the second motor is reached, or until the temperature limit of the second motor is reached. This means that the electrical energy generated by the first motor is always diverted to the second motor, and the system can otherwise function normally.

[0011] The system may further include a third motor, in which case the controller is configured to divert a portion of the generated electrical energy to the third motor. This means that the system can use additional sinking capacity as needed.

[0012] The system may be equipped with a power source such as a battery, in which case the controller is configured to divert a portion of the generated electrical energy to the power source. This means that the battery can be recharged.

[0013] The second or third motor may be a multiphase motor such as a permanent magnet synchronous motor or PMSM. The low phase resistance of the PMSM helps to sink the electrical energy generated by the first motor.

[0014] The cargo handling device may include a system, wherein the cargo handling device may be configured to lift and move storage containers stacked on a grid framework structure, and the grid framework structure is To form a grid pattern comprising multiple grid spaces, the system comprises a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane, wherein the grid is supported by a set of upright members to form multiple vertical storage positions directly beneath the grid, such that containers are stacked vertically between the upright members and guided by the upright members, and the cargo handling device is A body or frame attached to a first set of wheels configured to engage with a first set of parallel tracks, and a second set of wheels configured to engage with a second set of parallel tracks, A drive assembly comprising either a first motor or a second motor, wherein either the first motor or the second motor is configured to drive either a first or second set of wheels to move the load handling device along either a first or second set of parallel rails, The container lifting assembly comprises either a first motor or a second motor, the other of which is configured to raise or lower the gripping device vertically. This means that when the second and first functions of the cargo handling device are performed, each of the first and second functions of the cargo handling device can provide a sink.

[0015] The cargo handling device may include a system configured to lift and move storage containers stacked on a grid framework structure, and the grid framework structure is To form a grid pattern comprising multiple grid spaces, the system comprises a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane, wherein the grid is supported by a set of upright members to form multiple vertical storage positions directly beneath the grid, such that containers are stacked vertically between the upright members and guided by the upright members, and the cargo handling device is A body or frame attached to a first set of wheels configured to engage with a first set of parallel tracks, and a second set of wheels configured to engage with a second set of parallel tracks, A drive assembly comprising either a first motor or a second motor, wherein either the first motor or the second motor is configured to drive either a first or second set of wheels to move the load handling device along either a first or second set of parallel rails, The load handling device comprises a reversing assembly having either a first motor or a second motor, the other of which is configured to raise or lower a first set of wheels and / or lower or raise a second set of wheels relative to the body or frame in order to engage and disengage the wheels with a parallel track. This means that when the second and first functions are performed, each of the first and second functions of the load handling device can provide a sink.

[0016] The cargo handling device may include a system, wherein the cargo handling device may be configured to lift and move storage containers stacked in a grid framework structure, and the grid framework structure is To form a grid pattern comprising multiple grid spaces, the system comprises a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane, wherein the grid is supported by a set of upright members to form multiple vertical storage positions directly beneath the grid, such that containers are stacked vertically between the upright members and guided by the upright members, and the cargo handling device is A body or frame attached to a first set of wheels configured to engage with a first set of parallel tracks, and a second set of wheels configured to engage with a second set of parallel tracks, A container lifting assembly comprising either a first motor or a second motor, wherein either the first motor or the second motor is configured to raise or lower a gripping device in the vertical direction. The load handling device comprises a reversing assembly having either a first motor or a second motor, the other of which is configured to raise or lower a first set of wheels and / or lower or raise a second set of wheels relative to the body or frame in order to engage and disengage the wheels with a parallel track. This means that when the second and first functions are performed, each of the first and second functions of the load handling device can provide a sink.

[0017] The cargo handling device may include a system, wherein the cargo handling device may be configured to lift and move storage containers stacked in a grid framework structure, and the grid framework structure is To form a grid pattern comprising multiple grid spaces, the system comprises a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane, wherein the grid is supported by a set of upright members to form multiple vertical storage positions directly beneath the grid, such that containers are stacked vertically between the upright members and guided by the upright members, and the cargo handling device is A body or frame attached to a first set of wheels configured to engage with a first set of parallel tracks, and a second set of wheels configured to engage with a second set of parallel tracks, A drive assembly comprising a first motor and a second motor, wherein the first motor is configured to drive a first set of wheels to move a load handling device along a first set of parallel rails, and wherein the second motor is configured to drive a second set of wheels to move a load handling device along a second set of parallel rails, optionally, A steering assembly configured to raise or lower a first set of wheels and / or lower or raise a second set of wheels relative to a body or framework to engage and disengage the wheels with parallel tracks. This means that when the second and first functionalities are respectively executed, each of the first and second functionalities (in this case, X and Y direction movement) of the load handling device can provide a sink.

[0018] In a second aspect, there is a method of diverting electrical energy using a system of any preceding aspect, the method comprising: driving a first motor, detecting electrical energy generated by the first motor, using a controller to divert the generated electrical energy to a second motor.

[0019] In a third aspect, there is a computer program comprising instructions which, when executed by a computer, cause the computer to perform the method of the second aspect.

Brief Description of the Drawings

[0020] The present invention will be described with reference to one or more exemplary embodiments as depicted in the accompanying drawings. [Figure 1] FIG. 1 shows a storage structure and a container. [Figure 2] FIG. 2 shows the tracks at the top of the storage structure illustrated in FIG. 1. [Figure 3] FIG. 3 shows the load handling device at the top of the storage structure illustrated in FIG. 1. [Figure 4] FIG. 4 shows a single load handling device with the container lifting means in the lowered configuration. [Figure 5A] FIG. 5A shows a cutaway view of a single load handling device with the container lifting means in the raised configuration. [Figure 5B]Figure 5B shows a cutaway view of a single cargo handling device in which the container lifting means is configured for both upward and downward movement. [Figure 6] Figure 6 is a schematic diagram of a cargo handling device with a direction change assembly. [Figure 7] Figure 7 shows an exemplary container lifting assembly. [Figure 8] Figure 8 is a schematic diagram of a cargo handling device according to the present invention. [Figure 9] Figure 9 shows a method according to the present invention. [Figure 10] Figure 10 shows a system according to the present invention. [Modes for carrying out the invention]

[0021] Online retail businesses that sell multiple product lines, such as online grocery stores and supermarkets, require systems capable of storing tens or even hundreds of thousands of different product lines. Using single-product stacks in such cases is impractical because it requires a very large floor area to accommodate all the necessary stacks. Furthermore, single-product stacks are an inefficient solution when they are only desirable for storing small quantities of a few items, such as perishable goods or items that are not ordered very often.

[0022] International patent application WO98 / 049075A (Autostore), the contents of which are incorporated herein by reference, describes a system in which multiple product stacks of containers are arranged within a frame structure.

[0023] PCT Publication No. WO2015 / 185628A (Ocado) describes a further known storage and fulfillment system in which container stacks are arranged within a grid framework structure. Containers are accessed by one or more loading / unloading devices, alternatively known as "bots," operating on tracks located at the top of the grid framework structure. This type of system is schematically illustrated in Figures 1 to 3 of the attached drawings.

[0024] As shown in Figures 1 and 2, stackable containers 10, also known as "bins," are stacked on top of each other to form a stack 12. The stack 12 is located, for example, within a grid framework structure 14 in a warehouse storage environment or a manufacturing environment. The grid framework structure 14 consists of multiple storage columns or grid columns. Each grid within the grid framework structure has at least one grid column for storing the stack of containers. Figure 1 is a schematic perspective view of the grid framework structure 14, and Figure 2 is a schematic top view showing a stack 12 of bins 10 located within the framework structure 14. Each bin 10 typically holds multiple product items (not shown). The product items in the bin 10 may be of the same product type or different product types, depending on the application.

[0025] The grid framework structure 14 comprises a plurality of upright members 16 supporting horizontal members 18, 20. A first set of parallel horizontal grid members 18 is positioned perpendicular to a second set of parallel horizontal members 20 in a grid pattern, such that they form a horizontal grid structure 15 supported by the upright members 16. The members 16, 18, 20 are typically manufactured from metal. The bins 10 are stacked between the members 16, 18, 20 of the grid framework structure 14 so as to guard the horizontal movement of the stack 12 of bins 10 and guide the vertical movement of the bins 10.

[0026] The top level of the grid framework structure 14 includes rails 22 arranged in a grid pattern across the top of the stacks 12. Referring to Figure 3, the rails or stacks 22 guide multiple load handling devices 30. A first set 22a of parallel rails 22 guides the movement of the robot load handling devices 30 in a first direction (e.g., the X direction) across the top of the grid framework structure 14. A second set 22b of parallel rails 22, positioned perpendicular to the first set 22a, guides the movement of the load handling devices 30 in a second direction (e.g., the Y direction) perpendicular to the first direction. In this way, the rails 22 allow the robot load handling devices 30 to move laterally in two dimensions within the horizontal XY plane. The load handling devices 30 can be moved to any position above the stacks 12.

[0027] Known forms of cargo handling devices 30 shown in Figures 4, 5A, and 5B are described in PCT Patent Publication WO2015 / 019055 (Ocado), incorporated herein by reference, where each cargo handling device 30 covers a single grid space or grid cell of the grid framework structure 14. This configuration allows for a higher density of cargo handlers and, therefore, a higher throughput for a system of a given size.

[0028] The cargo handling device 30 comprises a vehicle 32, which is positioned to move on rails 22 of a frame structure 14. A first set of wheels 34, consisting of a pair of wheels 34 at the front of the vehicle 32 and a pair of wheels 34 at the rear of the vehicle 32, is positioned to engage with two adjacent rails of the first set 22a of rails 22. Similarly, a second set of wheels 36, consisting of pairs of wheels 36 on each side of the vehicle 32, is positioned to engage with two adjacent rails of the second set 22b of rails 22. Each set of wheels 34 and 36 can be raised and lowered via a reversing assembly (an example of which is shown in Figure 6), so that either the first set of wheels 34 or the second set of wheels 36 is always engaged with the respective sets of rails 22a and 22b. When the first set of wheels 34 is engaged with the first set of rails 22a and the second set of wheels 36 is fully lifted off the rails 22, the first set of wheels 34 can be driven via a drive assembly housed in the vehicle 32 to move the load handling device 30 in the X direction. To achieve movement in the Y direction, the first set of wheels 34 is lifted away from the rails 22, and the second set of wheels 36 is lowered and engaged with the second set 22b of the rails 22. The drive assembly can then be used to drive the second set of wheels 36 to move the load handling device 30 in the Y direction.

[0029] The cargo handling device 30 is equipped with a container lifting device or assembly, such as a crane mechanism (an example of which is shown in Figure 7), for lifting storage containers from above. The lifting device comprises a winch tether or cable 38 wound on a spool or reel and a gripper device 39. The lifting device shown in Figure 4 comprises a set of four vertically extending lifting tethers 38. The tethers 38 are connected to the gripper device 39, for example, at each of the four corners of the lifting frame, or near thereto, for a releasable connection to the storage container 10. For example, each tether 38 is located at each of the four corners of the lifting frame, or near thereto. The gripper device 39 is configured to releasably grip the top of the storage container 10 in order to lift the storage container 10 from a stack of containers in the type of storage system shown in Figures 1 and 2. For example, the lifting frame 39 may include a pin (not shown) that engages with a corresponding hole (not shown) in the rim forming the top surface of the bin 10, and a slide clip (not shown) that can engage with the rim to grip the bin 10. The clip is driven to engage with the bin 10 by a suitable drive mechanism housed within the lifting frame 39, which is powered and controlled by signals transmitted through the cable 38 itself or through a separate control cable (not shown).

[0030] To remove the bin 10 from the top of the stack 12, the load handling device 30 is first moved in the X and Y directions to the position of the gripper device 39 above the stack 12. The gripper device 39 is then lowered vertically in the Z direction to engage with the bin 10 at the top of the stack 12, as shown in Figures 4 and 5B. The gripper device 39 grasps the bin 10 and is then pulled up onto the cable 38 together with the attached bin 10. At the top of its vertical movement, the bin 10 is held above the rail 22 housed within the vehicle body 32. In this manner, the load handling device 30 can be moved to different positions in the XY plane to transport the bin 10 to a different location, carrying the bin 10 together with the load handling device 30. Upon reaching a target location (e.g., another stack 12, an access point within the storage system, or a conveyor belt), the bin or container 10 can be lowered from the container housing and released from the grabber device 39. The cable 38 is long enough to allow the load handling device 30 to retrieve and place the bin from any level of the stack 12, including floor level.

[0031] As shown in Figure 3, multiple identical loading / unloading devices 30 are provided, and each loading / unloading device 30 can operate simultaneously to increase the system throughput. The system illustrated in Figure 3 may include specific locations known as ports, where bins 10 can be transported into or out of the system. Each port is associated with an additional conveyor system (not shown), so that bins 10 transported to a port by a loading / unloading device 30 can be transported by the conveyor system to another location, for example, a picking station (not shown). Similarly, bins 10 can be moved from an external location to a port, for example, a binning station (not shown), by the conveyor system, and then transported by the loading / unloading device 30 to a stack 12 to replenish the stock in the system.

[0032] Each cargo handling device 30 can lift and move one bin 10 at a time. The cargo handling device 30 has a container receiving cavity or recess 40 at its lower part. The recess 40 is sized to accommodate a container 10 when lifted by the lifting mechanism, as shown in Figures 5A and 5B. When inside the recess, the container 10 is lifted away from the rail 22 below, and as a result, the vehicle 32 can move laterally to different grid positions.

[0033] If it is necessary to retrieve a bin 10b ("target bin") that is not located at the top of stack 12, the bins 10a ("non-target bins") above it must first be moved to allow access to the target bin 10b. This is achieved in an operation referred to below as "digging." Referring to Figure 3, during the digging operation, one of the loading handling devices 30 sequentially lifts each non-target bin 10a from the stack 12 containing the target bin 10b and places them in an empty position in another stack 12. The target bin 10b is then accessed by the loading handling device 30 and can be moved to a port for further transport.

[0034] Each of the cargo handling devices 30 can be operated remotely under the control of a central computer. Each individual bin 10 in the system is tracked, and the appropriate bin 10 can be retrieved, transported, and replaced as needed. For example, the location of each non-target bin 10 is logged so that non-target bins 10a can be tracked during the digging operation.

[0035] Wireless communication and networks may be used to provide a communication infrastructure from a master controller to one or more cargo handling devices operating on the grid structure, for example, via one or more base stations. In response to receiving commands from the central computer, controllers within the cargo handling devices are configured to control the movement of the cargo handling devices by controlling various drive mechanisms. For example, a cargo handling device may be commanded to retrieve a container from a target storage column at a specific location on the grid structure. This command may include various movements in the XY plane of the grid structure 15. As described above, upon reaching the target storage column, the lifting mechanism may be operated to grasp and lift the storage container 10. Once the container 10 is housed in the container receiving space 40 of the cargo handling device 30, the container 10 is then transported to another location on the grid structure 15, for example, a "drop-off port". At the drop-off port, the container 10 is lowered to a suitable picking station to allow the retrieval of any items within the storage container. The movement of the cargo handling device 30 on the grid structure 15 may also involve the cargo handling device 30 being instructed to move to a charging station located around the grid structure 15.

[0036] To operate the cargo handling devices 30 on the grid structure 15, each cargo handling device 30 is equipped with a motor for driving wheels 34, 36. The wheels 34, 36 may be driven via one or more belts connected to the wheels, or they may be driven individually by motors incorporated into the wheels. In the case of a single-cell cargo handling device (where the installation area of ​​the cargo handling device 30 occupies a single grid cell 17), the motors for driving the wheels can be integrated into the wheels because the available space within the vehicle body is limited. For example, the wheels of a single-cell cargo handling device are driven by their respective hub motors. Each hub motor comprises an outer rotor having multiple permanent magnets arranged to rotate around a wheel hub with coils forming an inner stator.

[0037] The system described with reference to Figures 1 to 5 has many advantages and is suitable for a wide range of storage and retrieval operations. In particular, it allows for very dense storage of products and provides a very economical way to store a large range of different items in bin 10, while also allowing rational and economical access to all of bin 10 when needed for picking.

[0038] An exemplary steering assembly (further described in PCT Publication WO2021175922A1 (Ocado) and PCT Application PCT / EP2022 / 073670 (Ocado)) is shown in Figure 6. As seen in Figure 6, a first pair of steering mechanisms 610 are positioned on opposing faces within the body or frame 602 of the cargo handling device to control the position of a first set of wheels 36, and a second pair of steering mechanisms 610 are positioned on orthogonal opposing faces within the body or frame of the cargo handling device to control the position of a second set of wheels 38. Thus, each face of the cargo handling device is equipped with a steering mechanism 610. The pairs of steering mechanisms 610 are mechanically coupled to the steering mechanism via a steering or drive belt 608 that substantially encircles the cargo handling device frame 602.

[0039] The output of the direction-changing mechanism is transmitted to the wheels 34, 36 via a chassis that converts the horizontal motion of the direction-changing mechanism into vertical motion of the wheels. In some arrangements, the direction-changing mechanism may be attached via sliding bearings to a rod arrangement that extends along the surface of the load-handling device 30 between each of the horizontal edges of the load-handling device 30. The rod arrangement may be attached to corner pieces at the first and second ends.

[0040] The wheel sets 34 and 36 can be moved simultaneously, for example, via a motor (not shown) and a drive belt 608, so as to engage the X and / or Y direction wheel sets with the rails of the storage system grid. Driving the motor clockwise can move the wheel mountings on a surface upward, raising the wheels on that surface and lowering the wheels on a surface perpendicular to the first surface, or vice versa.

[0041] An exemplary container lifting assembly (further described in PCT application PCT / EP2022 / 081364 (Ocado)) is shown in Figure 7. In Figure 7, the lifting assembly 700 has four spools 701, 702, 703, and 704 for winding and unwinding each tether 38. Spools 701 and 702 are on drive shaft 705, and spools 703 and 704 are on drive shaft 706. Drive shafts 705 and 706 are configured to rotate in opposite directions when driven by a motor. By rotating drive shafts 705 and 706 in opposite directions, each tether 38 can be positioned at or near the corners of the lifting assembly. In particular, as shown in Figure 7, the points where each tether is wound onto or unwound from the spool are at or near the respective corners of the lifting assembly. This allows the tether to connect to the container gripping device 39 at each corner of the gripping assembly, increasing stability when raising and lowering the container gripping device 39. Figure 7 shows an example of how the drive shafts 705 and 706 can rotate in opposite directions. The drive shafts 705 and 806 are connected to pulleys 710 and 711, respectively. Pulley 707 (or 709) is connected to the shaft / rotor of a motor (not shown in Figure 7). The drive belt 708 transmits torque to pulleys 709, 710, and 711 so as to ensure that spools 701 and 702 and spools 703 and 704 rotate in opposite directions. In particular, pulleys 707 and 709 are positioned around pulley 711, resulting in rotation opposite to that of pulley 710.

[0042] Here, the load handling device 30 has three systems, each of which can use at least one motor, i.e., a repositioning assembly, a drive assembly, and a container lifting assembly. Each of the motors tends to generate power when subjected to rapid deceleration; that is, the motor generates more power than it consumes. Rapid deceleration of the motors can occur when the container gripping assembly is approaching a container in the grid assembly, or when the load handling device is arriving at a desired position on the grid framework structure 14, or when the repositioning assembly is completing a repositioning. This generated electrical energy could potentially cause the power supply to operate beyond its rating or capacity, which could then damage the power supply (i.e., the battery) and any connected circuits. It is possible to feed back the generated electrical energy to the power supply, but this is limited by the extent to which the power supply is charged. When the power supply (battery) is at or near full capacity, the power supply cannot sink the generated electrical energy, and attempting to do so could damage the power supply.

[0043] It is known that damping resistors are used to sink the generated electrical energy and dissipate the heat. When the generated electrical energy is detected, the damping resistor is connected to the power circuit (for example, by using a MOSFET switch) to absorb the generated electrical energy and dissipate the heat. However, in certain situations, such as in cargo handling devices, the use of damping resistors raises the problem that considerable space is required to effectively sink the generated electrical energy and dissipate the heat. Assuming that the generated electrical energy is important in the cargo handling device, the size of the damping resistor will vary accordingly. The circuit that controls the operation of the damping resistor must also be accommodated. Therefore, it is desirable to sink the generated electrical energy without using a damping resistor. It should be understood that this problem is common to all systems in which the electrical energy generated by a motor must be sinked. The above is merely an example of a motor used in a cargo handling device. The ability to sink the motor-generated electrical energy in any system while avoiding the above problem is desirable.

[0044] Figure 8 shows a schematic diagram 800 of a cargo handling device 30 according to the present invention. The dashed lines indicate the body 32 of the cargo handling device moving on the grid 22a / b via wheels 34 / 36. The container lifting assembly (as shown in Figures 4, 5A, 5B, and 7) has a motor 810 which can be driven to raise and / or lower the container gripping assembly 39. The reversing assembly has a motor 820 which can be driven so that either a first set of wheels 34 or a second set of wheels 36 is always engaged with the respective sets of rails 22a and 22b. The X / Y drive assembly has a motor 830 which can be driven to move the cargo handling device 30 in the X and / or Y directions. A processor or controller 840 can receive and transmit data to each of the container lifting assembly motor 810, the reversing motor 820, and the X and / or Y drive assembly motor 830. The processor / controller 840 can also communicate with a power supply 860, which is used to power the container lifting assembly motor 810, the direction change motor 820, and the X and / or Y drive assembly motor 830, respectively. Any data used by the processor / controller 840 may be stored in the storage device 850. The data in the storage device 850 may be periodically transmitted for further processing over one or more networks, such as a base station.

[0045] Figure 9 shows the steps of Method 900 for use in a system with two motors, such as those used in a cargo handling device. It should be understood that the Method in Figure 9 can be performed using a processor / controller (e.g., the processor / controller 840 in the cargo handling device in Figure 8). In step 910, the first motor (which may be one of the container lifting assembly motor 810, the direction change motor 820, or the X and / or Y drive assembly motor 830) is driven. The processor / controller (such as the processor / controller 840) controls the speed of the first motor, and therefore acceleration and deceleration. When the first motor decelerates rapidly, the first motor generates more electrical energy than it consumes.

[0046] In step 920, the electrical energy generated by the first motor is detected. This can be done by monitoring the voltage on the busbar connecting the power supply to the first motor. The energy generated by the first motor results in an increase in the voltage on the busbar, which can be detected using appropriate circuitry. The busbar can be monitored to detect a threshold voltage indicating the generated electrical energy. For example, the threshold may be set to the rating of the power supply providing power to the first motor. A voltage on the busbar exceeding the threshold indicates the generated electrical energy. It will be understood that the threshold may be set depending on the power supply, the first motor, and the system in which the second motor is used.

[0047] In step 930, once a threshold voltage is detected, the generated electrical energy is diverted to a second motor (which may be one of the container lifting assembly motor 810, the reversing motor 820, or the X and / or Y drive assembly motor 830, and is not driven as the first motor). This means that any generated electrical energy that could potentially damage the power supply is diverted to the second motor. In this step, the second motor is not driven. The armature windings of the second motor have been found to act as an active current and heat sink for the electrical energy generated by the first motor. In particular, motors tend to have low resistance (or low phase resistance) and relatively high thermal mass. Any damage to the power supply and / or system can be avoided. Furthermore, some of the electrical energy generated by the first motor may be directed to recharge the power supply.

[0048] The generated electrical energy can be diverted until one of the following conditions is met: 1. The voltage on the busbar falls below a threshold voltage; 2. The current limit of the second motor is reached; 3. The temperature limit of the second motor is reached. In the case of condition 1, a proportional-integral (PI) controller can be used to maintain the bus voltage at its threshold voltage. The input to the PI controller may be the difference between the measured voltage on the busbar and the threshold voltage, and the output of the PI controller may be the current delivered to the second motor. Any suitable sensor can be used to determine whether condition 2 or 3 is met. Once either condition 2 or 3 is met, the generated electrical energy can be directed to recharge the power supply or another motor in the system. However, if it is not possible to direct the energy to the power supply or another motor due to power supply saturation or the unavailability of another motor, the braking performance of the first motor can be modified; that is, the deceleration of the first motor (which results in the generated electrical energy) is reduced.

[0049] In one implementation, the controller uses magnetic field direction control (FOC) or vector control with a second motor, which may be a multiphase motor such as a permanent magnet synchronous motor (PMSM). FOC or vector control controls the motor using two currents to define the respective orthogonal d-axis (direct axis) and q-axis (transverse axis) components. The d-axis generates magnetic flux, and the q-axis generates torque. The current defining the d-axis is generally known to be lost compared to the torque-generating current defining the q-axis. Therefore, if the processor uses FOC or vector control to configure the motor so that all the generated electrical energy is redirected along the d-axis, there is no risk that the generated electrical energy will generate torque in the second motor.

[0050] This may be useful in certain situations, such as when the cargo handling device is stationary on tracks 22a,b and the container lifting assembly is raising or lowering the container. In this scenario, the container lifting assembly motor 810 would act as the first motor, and one of the X / Y drive assembly motors 830 would act as the second motor. If the drive assembly motor 830 sinks the electrical energy generated by the container lifting assembly motor 810, the sunk energy will not be diverted to the q-axis, and the cargo handling device will not move in the X / Y direction. Considering the reverse scenario, where one of the X / Y drive assembly motors 830 acts as the first motor and the container lifting assembly motor 810 acts as the second motor, there is no risk of the container gripping assembly descending when the cargo handling device is moving along tracks 22a,b.

[0051] As described above, different motors can be used for movement in the X and Y directions, depending on the direction in which the cargo handling device moves along the track. Therefore, if the first motor is responsible for movement in the X direction (or X direction), the second motor can be responsible for movement in the Y direction (or X direction). In this scenario, the set of wheels for movement in the Y direction (or X direction) is not engaged with the track, and therefore there is no risk of the cargo handling device moving in the Y direction (or X direction), even if electrical energy is diverted to the q-axis (and thus introduces torque). This means that the use of magnetic field direction control or vector control is not required, and therefore the diverting of generated electrical energy is simplified.

[0052] Similarly, a repositioning assembly motor may be configured not to generate torque when functioning as a second motor. Generally, a second motor of a cargo handling device is prevented from performing its primary function (such as moving the cargo handling device, repositioning the cargo handling device, or lifting the container gripping assembly) when it acts as a sink for the electrical energy generated by the first motor of the cargo handling device in the process of performing that primary function. More generally, the second motor is configured to sink the electrical energy generated by the first motor so as to prevent the second motor from generating torque.

[0053] To ensure that the generated electrical energy is diverted along the d-axis, the d-axis of the second motor may be tracked, and the generated electrical energy may be directed along the last tracked orientation of the d-axis before the second motor acts as a sink for the electrical energy generated by the first motor. Alternatively, the q-axis may be tracked, and the d-axis may be applied in a direction perpendicular to the last tracked orientation of the q-axis before it acts as a sink for the electrical energy generated by the first motor. Assuming that the d-axis and q-axis are orthogonal and relative to the rotor, the actual positions of the d-axis and q-axis can be determined using tracking the rotor's position. In contrast to using the last known position of the d-axis before the second motor acts as a sink for the electrical energy generated by the first motor, the d-axis can be tracked in real time. This ensures that the current is sunk using the d-axis despite the movement of the d-axis and q-axis.

[0054] Figure 10 shows a schematic diagram of a circuit block that may be used to implement the method of Figure 9. As shown in Figure 10, the processor / controller 1010 interfaces with a power supply 1020 such as a battery, a first motor 1030, a busbar circuit 1040, an energy bypass circuit 1050, and a second motor 1060. The processor / controller 1010 communicates with the power supply 1020 and the first motor 1030 to drive the motors according to step 910. The busbar circuit 1040 interfaces with the busbar 1025 to monitor the voltage on the busbar 1025. The busbar circuit 1040 interfaces with the processor / controller 1010 and the electrical energy bypass circuit 1050 to control electrical energy bypass when a threshold voltage is detected on the busbar. The busbar circuit 1040 and the energy bypass circuit 1050 can then bypass any excess voltage on the busbar to the second motor 1060. The busbar circuit 1040 and the electrical energy bypass circuit 1050 can be implemented using the PI controller described above. The processor / controller 1010 interfaces with the second motor 1060, which can be used to control the second motor so that the energy generated by the first motor is bypassed along the d-axis of the second motor.

[0055] In this document, the phrase "movement in the n direction" (and related expressions) where n is one of x, y, and z is intended to mean movement substantially along or parallel to the n-axis in either direction (i.e., towards the positive end of the n-axis or towards the negative end of the n-axis).

[0056] In this document, the term “connect” and its derivatives are intended to include the possibility of direct and indirect connection. For example, “x is connected to y” is intended to include the possibility that x is directly connected to y without any intervening components, and the possibility that x is indirectly connected to y with one or more intervening components. When direct connection is intended, the terms “directly connected,” “direct connection,” or similar terms are used. Similarly, the term “support” and its derivatives are intended to include the possibility of direct and indirect contact. For example, “x supports y” is intended to include the possibility that x directly supports y and directly contacts y without any intervening components, and the possibility that x indirectly supports y with one or more intervening components that contact x and / or y. The term “attach” and its derivatives are intended to include the possibility of direct and indirect attachment. For example, the statement "x is attached to y" is intended to include both the possibility that x is directly attached to y without any intervening components, and the possibility that x is indirectly attached to y with one or more intervening components.

[0057] In this specification, the term “to comprise” and its derivatives are intended to have an inclusive, rather than exclusive, meaning. For example, “x comprises y” is intended to include the possibility that x comprises one and just one y, multiple ys, or one or more ys and one or more other elements. When an exclusive meaning is intended, the phrase “x consists of y” is used, meaning that x comprises only y and nothing else.

[0058] In this specification, “controller” is intended to include any hardware suitable for controlling (e.g., providing instructions to) one or more other components. For example, a processor with one or more memories and appropriate software processes data about one or more components and sends appropriate instructions to the components so that the components can perform their intended functions.

[0059] As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural form unless the context explicitly indicates otherwise. It will be further understood that the terms “equipped with” and / or “equipped with” when used herein specify the presence of the described feature, integer, step, action, element, and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, actions, elements, components, and / or groups thereof.

[0060] The present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment that includes both hardware and software elements. In a preferred embodiment, the present invention is implemented in software.

[0061] Furthermore, the present invention may take the form of a computer program embodied as a computer-readable medium having computer-executable code for use by or with a computer. For the purposes of this document, a computer-readable medium may be any tangible device that contains, stores, communicates, propagates, or transfers a program for use by or in connection with a computer. Furthermore, a computer-readable medium may be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device), or a propagation medium. Examples of computer-readable mediums include semiconductor or solid memory, magnetic tape, removable computer diskettes, random access memory (RAM), read-only memory (ROM), rigid magnetic disks, and optical disks. Current examples of optical disks include compact disks-read-only memory (CD-ROM), compact disks-read / write (CD-R / W), and DVDs.

[0062] The flowchart in the drawings illustrates the architecture, functionality, and operation of possible implementations of the methods according to various embodiments of the present invention. In this regard, each block in the flowchart may represent a module, segment, or part of code comprising one or more executable instructions for implementing a specified logical function. Note that in some alternative implementations, the functions shown in the blocks may be performed in a different order than shown in the diagram. For example, two blocks shown consecutively may actually be executed substantially simultaneously, or the blocks may be executed in reverse order depending on the functionality involved. Note that each block in the flowchart and any combination of blocks in the flowchart may be implemented by a dedicated hardware-based system that performs a specified function or operation, or a combination of dedicated hardware and computer instructions.

[0063] The above description is given only as an example, and it will be understood that various modifications can be made by those skilled in the art. Although various embodiments have been described above with some degree of specificity or by reference to one or more individual embodiments, those skilled in the art can make numerous modifications to the disclosed embodiments without departing from the scope of the invention.

Claims

1. A system for dissipating energy generated by a motor, The first motor and The second motor and Controller and The controller is equipped with, The first motor is driven, The electrical energy generated by the first motor is detected, A system configured to divert the generated electrical energy to the second motor.

2. The system according to claim 1, wherein the controller is configured to use field-directed control or vector control to control the second motor so as to sink the generated electrical energy.

3. The system according to claim 2, wherein the controller is configured to use field-directed control or vector control to sink all of the generated electrical energy in the straight axis of the second motor.

4. The system according to any one of claims 1 to 3, comprising a busbar configured to supply power to the first motor and / or the second motor, wherein the controller is configured to monitor the voltage on the busbar to detect energy generated by the first motor.

5. The system according to claim 5, wherein the controller is configured to divert the generated electrical energy to the second motor when the voltage on the busbar meets a threshold.

6. The aforementioned controller, The voltage of the busbar falls below the threshold, or The current limit of the second motor is reached, or The system according to claim 6, configured to divert the generated electrical energy until the temperature limit of the second motor is reached.

7. The current setting point in the aforementioned straight axis is, The voltage of the busbar falls below the threshold, or The current limit of the second motor is reached, or The system according to claim 6, if dependent on claim 3, increases until the temperature limit of the second motor is reached.

8. The system according to any one of claims 1 to 7, wherein the system comprises a third motor, and the controller is configured to divert a portion of the generated electrical energy to the third motor.

9. The system according to any one of claims 1 to 8, wherein the system includes a power source such as a battery, and the controller is configured to divert a portion of the generated electrical energy to the power source.

10. The system according to any one of claims 1 to 9, wherein the second motor or, if dependent on claim 8, the third motor, comprises a multiphase motor such as a permanent magnet synchronous motor or a PMSM.

11. A cargo handling device comprising the system described in any one of claims 1 to 10.

12. The cargo handling device is configured to lift and move storage containers stacked in a grid framework structure, and the grid framework structure is To form a grid pattern comprising multiple grid spaces, the device comprises a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane, wherein the grid is supported by a set of upright members to form multiple vertical storage positions directly below the grid, such that containers are stacked vertically between the upright members through the multiple grid spaces and guided by the upright members, and the cargo handling device is A body or frame attached to a first set of wheels configured to engage with a first set of parallel tracks, and a second set of wheels configured to engage with a second set of parallel tracks, A drive assembly comprising either the first motor or the second motor, wherein either the first motor or the second motor is configured to drive the first or second set of wheels to move the load handling device along a first or second set of parallel rails, A cargo handling device according to claim 11, comprising a container lifting assembly comprising the other of the first motor or the second motor, wherein the other of the first motor or the second motor is configured to raise or lower a gripping device vertically.

13. The cargo handling device is configured to lift and move storage containers stacked in a grid framework structure, and the grid framework structure is To form a grid pattern comprising multiple grid spaces, the device comprises a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane, wherein the grid is supported by a set of upright members to form multiple vertical storage positions directly below the grid, such that containers are stacked vertically between the upright members through the multiple grid spaces and guided by the upright members, and the cargo handling device is A body or frame attached to a first set of wheels configured to engage with a first set of parallel tracks, and a second set of wheels configured to engage with a second set of parallel tracks, A drive assembly comprising either the first motor or the second motor, wherein either the first motor or the second motor is configured to drive the first or second set of wheels to move the load handling device along a first or second set of parallel rails, A cargo handling device according to claim 11, comprising a reversing assembly having the other of the first motor or the second motor, wherein the other of the first motor or the second motor is configured to raise or lower a first set of wheels and / or lower or raise a second set of wheels relative to the body or frame in order to engage and disengage the wheels with the parallel tracks.

14. The cargo handling device is configured to lift and move storage containers stacked in a grid framework structure, and the grid framework structure is To form a grid pattern comprising multiple grid spaces, the device comprises a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane, wherein the grid is supported by a set of upright members to form multiple vertical storage positions directly below the grid, such that containers are stacked vertically between the upright members through the multiple grid spaces and guided by the upright members, and the cargo handling device is A body or frame attached to a first set of wheels configured to engage with a first set of parallel tracks, and a second set of wheels configured to engage with a second set of parallel tracks, A container lifting assembly comprising either the first motor or the second motor, wherein either the first motor or the second motor is configured to raise or lower the gripping device in the vertical direction. A cargo handling device according to claim 11, comprising a reversing assembly having the other of the first motor or the second motor, wherein the other of the first motor or the second motor is configured to raise or lower a first set of wheels and / or lower or raise a second set of wheels relative to the body or frame in order to engage and disengage the wheels with the parallel tracks.

15. The cargo handling device is configured to lift and move storage containers stacked in a grid framework structure, and the grid framework structure is To form a grid pattern comprising multiple grid spaces, the device comprises a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane, wherein the grid is supported by a set of upright members to form multiple vertical storage positions directly below the grid, such that containers are stacked vertically between the upright members through the multiple grid spaces and guided by the upright members, and the cargo handling device is A body or frame attached to a first set of wheels configured to engage with a first set of parallel tracks, and a second set of wheels configured to engage with a second set of parallel tracks, A drive assembly comprising the first motor and the second motor, wherein the first motor is configured to drive a first set of wheels to move the load handling device along a first set of parallel rails, and wherein the second motor is configured to drive a second set of wheels to move the load handling device along a second set of parallel rails, optionally, A cargo handling device according to claim 11, comprising: a steering assembly configured to raise or lower a first set of wheels and / or lower or raise a second set of wheels relative to the body or frame in order to engage and disengage the wheels with a parallel track.

16. A method for diverting electrical energy using a system according to any one of claims 1 to 15, The first motor is driven, The electrical energy generated by the first motor is detected, The generated electrical energy is redirected to the second motor, A method comprising using the aforementioned controller.

17. A computer program comprising instructions, wherein when the program is executed by a computer, the computer causes the computer to perform the method according to claim 16.

Images