Patent Publication Number: US-2023142826-A1

Title: Material Handling Vehicle Charging Systems and Methods With Position Compensation

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is based on and claims priority to U.S. Provisional Pat. Application No. 63/277,434, filed on Nov. 9, 2021, which is incorporated herein by reference in its entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
    
    
     BACKGROUND 
     Material handling vehicles have been developed to transport goods loaded onto generally standardized transport platforms. For example, forklifts can be used to lift goods loaded onto a pallet and move the goods between locations in a facility such as a warehouse or a factory. Some material handling vehicles, such as automated guided vehicles (AGVs), can operate autonomously without a human operator. Other material handling vehicles are non-autonomous and are operated by a human. In any kind of material handling vehicle, systems and methods for improving operational efficiency are generally desired. For example, charging systems can be used to charge batteries in a variety of different material handling vehicles. 
     For certain types of vehicles there are training requirements imposed by various government agencies, laws, rules, and regulations. For example, the United States Department of Labor Occupational Safety and Health Administration (OSHA) imposes a duty on employers to train and supervise operators of various types of material handling vehicles. Recertification every three years is also required. In certain instances, refresher training in relevant topics shall be provided to the operator when required. In all instances, the operator remains in control of the material handling vehicle during performance of any actions. Further, a warehouse manager remains in control of the fleet of material handling vehicles within the warehouse environment. The training of operators and supervision to be provided by warehouse managers requires among other things proper operational practices including among other things that an operator remain in control of the material handling vehicle, pay attention to the operating environment, and always look in the direction of travel. 
     BRIEF SUMMARY 
     The present disclosure relates generally to systems and methods for positioning a charging plate relative to a collector plate of a material handling vehicle for charging (e.g., to align the charging plate with the collector plate). In some cases, the charging plate can be supported by a charging device with a position compensation system that can move the charging plate along one, two, three, or more directions to be in alignment with the collector plate, as may facilitate automatic charging of the material handling vehicle. 
     According to one aspect, the present disclosure provides a charging device for charging a battery of a material handling vehicle having a collector plate electrically coupled to the battery for charging. The charging device can include a stand having a stationary portion, a moveable portion that can move relative to the stationary portion, and one or more actuators can be configured to move the moveable portion of the stand relative to the stationary portion. A charging plate can be supported on the moveable portion for electrically coupling with the collector plate. A sensing array can be configured to detect a position of the charging plate relative to the collector plate. The sensing array can include a first sensor to detect a first position of the charging plate relative to the collector plate along a first direction and a second sensor to detect a first position of the charging plate relative to the collector plate along a second direction that can be different from the first direction. A position controller can be configured to receive a signal from the sensing array. Based on the signal, the position controller can operate the one or more actuators to move the moveable portion of the stand from a stored position in which the charging plate is not aligned with the collector plate to a charging position in which the charging plate is aligned with the collector plate for charging. 
     In some non-limiting examples, the first sensor can be a first retroreflective sensor that can be configured to detect a first reflective strip on the material handling vehicle and the second sensor can be a second retroreflective sensor that can be configured to detect a second reflective strip on the material handling vehicle. The position controller can be configured to operate the one or more actuators to move the moveable portion along the second direction to align the first retroreflective sensor with first reflective strip. The position controller can be configured to operate the one or more actuators to move the moveable portion along the first direction to align the second retroreflective sensor with the second reflective strip. The first direction can be perpendicular to the second direction. The first reflective strip can extend along the second direction and the second reflective strip can extend along the first direction. 
     In some non-limiting examples, the sensing array can be supported on the moveable portion of the stand and can further include a third sensor to detect a third position of the charging plate relative to the collector plate along a third direction. The third direction can be different from both the first direction and the second direction. The third sensor can be a position sensor that can be configured to determine a distance between the charging plate and the collector plate. The position controller can be configured to operate the one or more actuators to move the moveable portion along the third direction to align the charging plate with the collector plate. The third direction can be perpendicular to both the first direction and the second direction. 
     In some non-limiting examples, the charging device can further include a charge controller that can be configured to supply electrical current to the collector plate to wirelessly charge the battery via the collector plate. The charge controller can be configured to communicate with a battery management system of the material handling vehicle. 
     According to one aspect, the present disclosure provides a retrofit kit for charging a battery of a material handling vehicle. The retrofit kit can include a collector plate that can be configured to electrically couple to the battery and a support bracket that can be configured to couple to the material handling vehicle and to support the collector plate on the material handling vehicle. The retrofit kit can further include a first reflective strip and a second reflective strip that can be configured to be secured to the material handling vehicle, and a charging device. The charging device can include a stand having a stationary portion, a moveable portion that can be configured to move relative to the stationary portion, and one or more actuators that can be configured to move the moveable portion of the stand relative to the stationary portion. A charging plate and a sensing array can be configured to be supported on the moveable portion. The sensing array can be configured to detect a position of the charging plate relative to the collector plate. The sensing array can include a first retroreflective sensor to detect the first reflective strip to determine a first position of the charging plate relative to the collector plate along a first direction, and a second retroreflective sensor to detect the second reflective strip to determine a second position of the charging plate relative to the collector plate along a second direction. The second direction can be different from the first direction. A position controller can be configured to receive a signal from the sensing array. Based on the signal, the position controller can operate the one or more actuators to move the moveable portion of the stand from a stored position in which the charging plate is not aligned with the collector plate to a charging position in which the charging plate is aligned with the collector plate for charging. 
     In some non-limiting examples, the first direction can be perpendicular to the second direction. The first reflective strip can extend along the second direction and the second reflective strip can extend along the first direction. The position controller can be configured to operate a first actuator of the one or more actuators to move the moveable portion along the second direction to align the first retroreflective sensor with first reflective strip. The position controller can be configured to operate a second actuator of the one or more actuators to move the moveable portion along the first direction to align the second retroreflective sensor with the second reflective strip. 
     In some non-limiting examples, the sensing array can further include a third sensor to detect a third position of the charging plate relative to the collector plate along a third direction. The third direction can be different from both the first direction and the second direction. The third sensor can be a position sensor that can be configured to determine a distance between the charging plate and the collector plate. The position controller can be configured to operate a third actuator of the one or more actuators to move the moveable portion along the third direction to align the charging plate with the collector plate. 
     According to one aspect, the present disclosure provides a method for positioning a charging device for charging a battery of a material handling vehicle having a collector plate electrically coupled to the battery. The method can include, receiving, using a position controller, a first signal from a first retroreflective sensor. The first signal can indicate a first distance between a charging plate and the collector plate along a first direction. The first retroreflective sensor and the charging plate can be supported on a moveable portion of a stand that can be configured to be moved relative to a stationary portion of the stand. Using the position controller, a first actuator can be operated to move the moveable portion along the first direction to align the first retroreflective sensor with a first reflective strip supported on the material handling vehicle. The method can further include receiving, using the position controller, a second signal from a second retroreflective sensor. The second signal can indicate a second distance between the charging plate and the collector plate along a second direction. The second retroreflective sensor can be supported on the moveable portion. Using the position controller, a second actuator can be operated to move the moveable portion along the second direction to align the second retroreflective sensor with a second reflective strip supported on the material handling vehicle. 
     In some non-limiting examples, the method can further include receiving, using the position controller, a third signal from a position sensor. The third signal can indicate a third distance between the charging plate and the collector plate along a third direction. The position sensor can be supported on the moveable portion. Using the position controller, a third actuator can be operated to move the moveable portion along the third direction to move the collector plate to be at a predetermined distance from the collector plate for charging. 
     In some non-limiting examples, the method can further include receiving, using a charge controller, a fourth signal from a battery management system of the material handling vehicle. Based on the fourth signal, the charge controller can control a flow of electrical energy from the charging plate to the collector plate to charge the battery. 
     The foregoing and other aspects and advantages of the disclosure will appear from the following description. In the description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by way of illustration a preferred configuration of the disclosure. Such configuration does not necessarily represent the full scope of the disclosure, however, and reference is made therefore to the claims and herein for interpreting the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood and features, aspects and advantages other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such detailed description makes reference to the following drawings. 
         FIG.  1    is a partial schematic view of an automatic charging system for a material handling vehicle, according to aspects of the present disclosure; 
         FIG.  2    is a partial schematic view of another automatic charging system for a material handling vehicle, according to aspects of the present disclosure; 
         FIG.  3    is a partial schematic view of another automatic charging system for a material handling vehicle, according to aspects of the present disclosure; 
         FIG.  4    is a partial schematic view of another automatic charging system for a material handling vehicle, according to aspects of the present disclosure; 
         FIG.  5    is a partial schematic view of another automatic charging system for a material handling vehicle, according to aspects of the present disclosure; 
         FIG.  6    is a flowchart of a method of positioning an automatic charging system, according to aspects of the present disclosure; 
         FIG.  7    is a schematic view of a method of positioning an automatic charging system of  FIG.  6   , being implemented by the automatic charging system of  FIG.  5   , according to aspects of the present disclosure; and 
         FIG.  8    is an additional schematic view of the method of positioning an automatic charging system of  FIG.  6   , being implemented by the automatic charging system of  FIG.  5   , according to aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Before any aspects of the present disclosure are explained in detail, it is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other non-limiting examples and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof, as well as additional items. Likewise, “at least one of A, B, and C,” and the like, is meant to indicate A, or B, or C, or any combination of A, B, and/or C. Unless specified or limited otherwise, the terms “mounted,” “secured,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     It is also to be understood that any reference to an element herein using a designation such as “first,” “second,” and so forth does not limit the quantity or order of those elements, unless such limitation is explicitly stated. Rather, these designations may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements may be employed there or that the first element must precede the second element in some manner. 
     It is also to be appreciated that material handling vehicles (MHVs) are designed in a variety of classes and configurations to perform a variety of tasks. It will be apparent to those of skill in the art that the present disclosure is not limited to any specific material handling vehicle, and can also be provided with various other types of material handling vehicle classes and configurations, including for example, lift trucks, forklift trucks, reach trucks, SWING REACH® vehicles, turret trucks, side loader trucks, counterbalanced lift trucks, pallet stacker trucks, order pickers, transtackers, tow tractors, and man-up trucks, and can be commonly found in warehouses, factories, shipping yards, and, generally, wherever pallets, large packages, or loads of goods can be required to be transported from place to place. The various systems and methods disclosed herein are suitable for any of operator controlled, pedestrian controlled, remotely controlled, and autonomously controlled material handling vehicles. Further, the various system and methods disclosed herein are suitable for other vehicles, such as automobiles, busses, trains, tractor-trailers, farm vehicles, factory vehicles, and the like. 
     Conventional systems for material handling vehicles, for example, forklifts, utilize batteries (e.g., lead-acid batteries (LABs) or lithium-ion batteries (LIBs) as an energy source, and must be periodically charged to continue operating. Charging of material handling vehicles can be carried out using a charging system. Conventional charging systems can be configured as manual chargers, wherein an operator manually connects a charger to a material handling vehicle, or as automatic chargers, wherein a material handling vehicle is moved or moves within close proximity to an automatic charger and the automatic charger then charges the material handling vehicle without further operator assistance or input. 
     For example, some automatic charging systems utilizes an immovable charging pad or base plate that is fixedly mounted to a stationary surface (e.g., a floor) and a collector plate that is mounted onto a material handling vehicle (e.g., to an underside of a material handling vehicle) so that it moves with the material handling vehicle relative to the base plate. To charge the material handling vehicle, the material handling vehicle is positioned, by either an operator, or an autonomous or semi-autonomous system, so that the collector plate is disposed above the base plate, such that the base plate and the collector plate are in alignment with one another. That is, so that a pair of signal pilot contacts and a pair of charging power contacts of the base plate are in contact with corresponding signal pilot contacts and charging power contacts of the collector plate. Generally, such charging systems demand accurate positioning of the collector plate with respect to the base plate (e.g., within 0.5 inches or less of a fully aligned position). 
     In some cases, it can be advantageous to have an automatic charging system that can accommodate greater misalignments between the automatic charger and the material handling vehicle. For example, such an automatic charging system may allow multiple sizes and/or types of material handling vehicles to use the same automatic charger. Similarly, such automatic charging systems can provide more efficient usability by tolerating greater amounts of misalignment. By allowing greater misalignment, a charging system can allow an autonomous material handling vehicle to be automatically charged even if it has a larger stopping tolerance. Similarly, such a charging system can allow a material handling vehicle that is carrying a load to be charged without first having to drop the load, only to have to re-engage the load after charging has completed. 
     Accordingly, some non-limiting examples of automatic charging systems according to the present disclosure can provide for an automatic charger that is able to accommodate comparatively large misalignments (i.e., tolerances) between an automatic charger and a material handling vehicle to be charged (e.g., up to 2 feet of misalignment, or more), in one or more directions. In this way, the automatic charging system can charge a material handling vehicle even where the material handling vehicle is carrying or towing a load that is larger than the material handling vehicle itself. Additionally, some non-limiting examples of automatic charging systems according to the present disclosure can accommodate for misalignments in one or more directions, for example, a front-to-back or extension direction, a side-to-side or lateral direction, and/or an up-and-down or vertical direction. Relatedly, such automatic charging systems can include a positioning system that can be configured to detect the relative position of a collector plate and a base plate, and to adjust a position of the collector plate or the base plate, or both, to position the collector plate and the base plate in alignment with one another. 
       FIG.  1    illustrates a non-limiting example of an automatic charging system  100  (e.g., a wireless automatic charging system) for charging an energy source of a material handling vehicle  104 . The material handling vehicle  104  may be an automated guided vehicle (AGV), such as a fully- or semi-autonomous AGV, or a manually operated vehicle. The material handling vehicle  104  can include a mast  106  for raising and lowering a fork assembly  108  (or, in other non-limiting examples, a platform, an operator cabin, or other implement assemblies). That is, the mast  106  can be in the form of a telescoping mast with the fork assembly  108  attached thereto such that the fork assembly  108  can be selectively raised and lowered by the mast  106 . The fork assembly  108  may include one or more forks  110  that can engage a load, for example, a pallet. In the present non-limiting example, the illustrated fork assembly  108  can include a pair of forks  110 . In some non-limiting examples, the fork assembly  108  can be coupled to the mast  106  by a reach actuator. 
     The material handling vehicle  104  can further include an energy source  112  to power and/or operate various functions and systems of the material handling vehicle  104 . In the illustrated non-limiting example, the energy source  112  is provided as a battery  114  (e.g., a LIB or LAB), however, other types of batteries and energy sources may also be used. In some non-limiting examples, a material handling vehicle  104  can accept several different kinds of energy systems or batteries  114 . The battery  114  may include or be contained in a case  116 . The case  116  may be a counterweight case that can be configured to support the battery  114 . 
     The battery  114  may also include a battery management system (BMS)  120 , configured to monitor a state-of-charge (SOC) of the battery  114 , as well as monitoring and/or controlling charging and discharging of the battery  114 . In particular, with regard to charging the battery  114 , the BMS  120  can be configured to monitor or control the flow of electricity (i.e., electrical current) from a power receiving or collector plate  124 , which is coupled with the material handling vehicle  104 , to the battery  114 . The collector plate  124  can be configured as an electrical contact plate with physical electrical contacts for wired charging, or as wireless charging plate with an induction coil to provide contactless charging (i.e., wireless charging). 
     In the illustrated non-limiting example, the collector plate  124  can be configured as a wireless charging coil that can be mounted to (i.e., coupled with) an exterior side of the material handling vehicle  104 , although other mounting configurations are possible. For example, a collector plate  124  can be mounted to a different external surface of a material handling vehicle (e.g., a front, rear, top, or underside of a material handling vehicle), including any components thereof (e.g., the battery  114 ), or it can be internally mounted. Additionally, in some cases the collector plate  124  may include a base plate or bracket  126  that can be configured to couple with the material handling vehicle  104 . Furthermore, the collector plate  124  is illustrated as being a circular plate, but it may alternately be any other shape. 
     The collector plate  124  can be configured to receive power from a charging device to charge an energy source of the material handling vehicle  104 . For example, in the illustrated non-limiting example, the battery  114  of the material handling vehicle  104  can be charged by a charging device  130 . The charging device  130  can be configured as an automatic charging device that can be connected to an external power source, such as an outlet or power mains (i.e., power is supplied to the charging device  130  via the power source). Additionally, the charging device  130  can be configured as a wireless charging device that can include a power delivery or charging plate  132 . The charging plate  132  can be configured as a wireless charging coil that is supported by (i.e., coupled with) an adjustable charging base or stand  134 . In the illustrated non-limiting example, the charging plate  132  is configured as a circular plate that is similar in size to the collector plate  124 . In other non-limiting examples, the charging plate  132  can be configured to be another size and/or shape. Further, in other non-limiting examples, the charging plate  132  can be configured as an electrical contact plate with physical electrical contacts for wired charging. 
     To charge the battery  114  of the material handling vehicle  104 , the BMS  120  can operate a communication link (e.g., a wireless communication link) between the battery  114  and the charging device  130  to control charging of the battery  114 . More specifically, the BMS  120  may be in communication with a charge controller  144  of the charging device  130 . In this regard, the BMS  120  can command the charging device  130  to handle all charging functions without operator input (e.g., selecting a charging voltage and charging current). That is, the BMS  120  may control the charging device  130 , for example, by commanding the charge controller  144  to control a magnitude and/or direction of a current in the battery  114 . In other non-limiting examples, the BMS  120  may communicate with the charging device  130  to begin charging the battery  114  and the charge controller  144  can control the charging of the battery  114  (e.g., to command the charge controller  144  to supply an electrical current from the charging plate  132  to the collector plate  124  to charge the battery  114 ). 
     To charge the battery  114 , the collector plate  124  and the charging plate  132  should be generally aligned with one another. That is, in an ideal position, a central axis  136  of the collector plate  124  and a central axis  138  of the collector plate  124  can be coincident with one another. However, some deviation from the ideal position is permitted. For example, the automatic charging system  100  may be configured to tolerate up to 0.5 inches of misalignment (i.e., a parallel offset in a vertical or lateral direction) between the central axis  136  of the collector plate  124  and the central axis  138  of the charging plate. In addition, the collector plate  124  and the charging plate  132  may be spaced from each other by a gap  140 . In the ideal position, the gap  140  can be approximately 0.5 inches, but may range between greater than or equal to 0.1 inches to less than or equal to 1.5 inches. In other non-limiting examples, a collector plate and a charging plate may instead have electrical contacts that physical contact therebetween to charge a material handling vehicle. In such non-limiting examples, no gap would be present between the charging plate and the collector plate when they are aligned. 
     To ensure alignment of a collector plate and a charging plate, a charging device can include a position compensation system. In the illustrated non-limiting example, the charging device  130  can include a position compensation system  146  having a position controller  148  that can control the position of the charging plate  132  to move the charging plate  132  into alignment with the collector plate  124 . More specifically, as will be discussed in greater detail below, the stand  134  can include a moveable portion having various actuating structures and/or actuators that can be controlled (i.e., operated) by the position controller  148  to move the charging plate  132  into alignment with the collector plate  124 , as are described in greater detail below. The moveable portion can be operatively supported on a stationary portion, such as a stand base, and can be moved relative to the stationary portion (e.g., via operation of one or more actuators). In some non-limiting examples, the stationary portion can be secured to a generally immovable structure, for example, a ground or floor surface, or a wall. 
     In addition, the position compensation system  146  can include a sensing array  150  in communication with the position controller  148 , which may include, for example, one or more proximity sensors, retro-reflective sensors, visual cameras, 3D cameras, LIDAR, and/or other equivalent types of sensors as known in the art. In particular, the sensors of the sensing array  150  can be used to detect when the material handling vehicle  104  is in a charging area and/or the position of the collector plate  124  relative to the charging plate  132 . The sensing array  150  can be supported by the charging device  130 , the material handling vehicle  104 , or another structure, and can be configured to send input signals to the position controller  148 . That is, when the sensing array  150  detects that the material handling vehicle  104  is present, the sensing array  150  can send a corresponding signal to the position controller  148  to align the charging plate  132 . In other non-limiting examples, a signal to align the charging plate  132  may be provided, for example, by a central automation server, a warehouse management system, or a manual push button. 
     Accordingly, in response to a signal to align the charging plate  132 , the position controller  148  can operate the actuating structures via the actuators to move the charging plate  132   into alignment with the collector plate  124 . During movement of the charging plate  132 , the position controller  148  may receive additional input signals from the sensing array  150 , which can be used to indicate a current position of the charging plate  132 . In other non-limiting examples, one or both of the collector plate  124  and the charging plate  132  can be configured to move. 
     In the illustrated non-limiting example, the charging device  130  can be configured to move the charging plate  132  along an extension or first direction  152  extending between the stand  134  and the material handling vehicle  104  to adjust the gap  140  between the collector plate  124  and the charging plate  132 . To facilitate movement along the first direction  152 , the stand  134  can include an actuating structure, namely, an extension arm  154  (e.g., a moveable portion) that supports the charging plate  132  on a bracket  156 , which can be coupled to a distal end of the extension arm  154 . 
     In the illustrated non-limiting example, the extension arm  154  can be configured as a linear extension arm having an extension rod  158  that can be moveably received in a tube  160  (e.g., a stationary portion), which can be fixedly coupled with the ground or another non-moving structure (e.g., a wall or a girder). As illustrated, the extension rod  158  can be configured as an elongate member with a square cross-section and the tube  160  can be configured as a correspondingly shaped tube, although other configurations are possible. The extension rod  158 , and thus the charging plate  132 , can be moved relative to the tube  160  along the first direction  152  by an actuator  162 . More specifically, the extension rod  158  can be moved between a stored position where the extension rod  158  is fully retracted into the tube  160  and a charging position where the extension rod  158  is moved by the actuator  162  to position the charging plate  132  in alignment with the collector plate  124 . As illustrated, the actuator  162  can be configured as a hydraulic or electronic actuator that is operated by the position controller  148 ; however, other types of actuators may also be used (e.g., pneumatic actuators). In other non-limiting examples, other types and configurations of actuating structures and/or actuators may be used to move the charging plate along the first direction  152 . 
     To ensure and determine when the gap  140  is within the permitted tolerance, the sensing array  150  can include a position sensor  164  that can be in communication with the position controller  148 . The position sensor  164  can be configured to send position signals (i.e., position data) that are received and interpreted by the charge controller  144 . For example, in the illustrated non-limiting example, the position sensor  164  can be configured as a proximity sensor that is mounted adjacent the charging plate  132 , although other configurations and types of sensors (e.g., a laser measurement device) are possible. In response to the signals from the position sensor  164 , the position controller  148  can operate the actuator  162  to move the charging plate  132  along the first direction  152  until the gap  140  is within a specified tolerance. Once alignment has been achieved, which may by indicated by a signal from the position sensor  164 , the charging process can commence. Accordingly, the position controller  148  and the BMS  120  may communicate with one another that the collector plate  124  and the charging plate  132  are aligned, after which the BMS  120  can communicate with the charge controller  144  to begin charging the battery  114 . 
     In other non-limiting examples, a position compensation system can be configured to move a charging plate in other directions. For example, a position compensation system may be configured to move a charging plate in a second, side-to-side or lateral direction that is oriented along a length or width of the material handling vehicle  104  (e.g., a direction parallel and along the forks). Alternatively or additionally, a position compensation system may be configured to move a charging plate in a third or vertical direction corresponding with a height of the material handling vehicle and/or a distance from the ground. Accordingly, in other non-limiting examples, a sensor array can include additional sensors to determine alignment along a second and/or third direction. 
     Turning to  FIG.  2   , another non-limiting example of an automatic charging system  200  is illustrated. The automatic charging system  200  is similar to the automatic charging system  100 , with like reference numeral referring to like features, except where otherwise indicated. In particular, the automatic charging system  200  can include a material handling vehicle  204  having an energy source  212  configured as a battery  214  and a BMS  220 , which can be configured to control the charging of (i.e., controlling the flow of current to) the battery  214  via a collector plate  224  that can be coupled to the material handling vehicle  204 . More specifically, collector plate  224  can be configured to receive power from a charging device  230  having a corresponding charging plate  232 , which is mounted to an adjustable stand  234 . That is, when the collector plate  224  and the charging device  230  are aligned, the BMS  220  can wirelessly communicate with a charge controller  244  of the charging device  230  to charge the battery  214  (e.g., to command the charge controller  244  to supply an electrical current from the charging plate  232  to the collector plate  224  to charge the battery  214 ). 
     To align the collector plate  224  and the charging plate  232 , the BMS  220  can be further configured to communicate with a position compensation system  246 . More specifically, the position compensation system  246  can include a position controller  248  that can communicate with the BMS  220 , and, in response to input from a sensing array  250 , detect the material handling vehicle  204  and move the charging plate  232  into alignment with the collector plate  224  via a number of actuating structures and/or actuators. 
     In the illustrated non-limiting example, the position compensation system  246  can be configured to move the charging plate  232  along an arcuate or curved path  252 . In this way, the position compensation system  246  can adjust the position of the charging plate  232  along the curved path  252  to accommodate lateral misalignments along the curved path  252 . Relatedly, the charging plate  232  can be moved along the curved path  252  between a stored position and a charging position. Such configurations may be beneficial, for example, where a charging device  230  is to be installed on a corner of a travel path for a material handling vehicle. In other non-limiting examples, position compensation system  246  can be configured to move the charging plate  232  along one or more additional directions. 
     To facilitate movement of the charging plate  232  along the curved path  252 , the stand  234  can include an actuating structure, namely, a swing arm  254  (e.g., an extension arm or moveable portion) and a linkage  256  that are operatively coupled with a base  258  (e.g., a stationary portion) to rotate the swing arm  254 . More specifically, the swing arm  254  can be configured as an elongate member that can be pivotally coupled (e.g., at a pinned connection) with the base  258  at a first end  260  and that can be configured to support the charging plate  232  at a distal or second end  262 . The linkage  256  includes a first link  264  and a second link  266  that are pivotally coupled with one another so that they can rotate relative to one another. In addition, the first link  264  and second link  266  are pivotally coupled with and rotate relative to the swing arm  254  and the base  258 , respectively. Put another way, the swing arm  254 , the linkage  256 , and the base  258  can form a four-bar linkage to rotate the charging plate  232  about the base  258 . In this way, the swing arm  254  can be rotated about its connection to the base  258  to move the charging plate  232  into alignment with the collector plate  224 . 
     Furthermore, an actuator  268  can be operatively coupled between the base  258  and the linkage  256  to move the swing arm  254  relative to the base  258 . In the illustrated non-limiting example, the actuator  268  is coupled with the linkage  256  proximate the pivoting connection between the first link  264  and the second link  266 , although other configurations are possible, for example, coupling the actuator  268  along the first link  264 . The actuator  268  can be a linear actuator as known in the art (e.g., a hydraulic, pneumatic, or electric actuator) and can be controlled or otherwise operated by the position controller  248 . More specifically, the position controller  248  can receive input signals from a position sensor  270  (e.g., a proximity sensor or a laser measurement device) and use those signals to determine when the charging plate  232  in alignment with the collector plate  224 . 
     Turning to  FIG.  3   , another non-limiting example of an automatic charging system  300  is illustrated. The automatic charging system  300  is similar to the automatic charging system  100 , with like reference numeral referring to like features, except where otherwise indicated. In particular, the automatic charging system  300  can include a material handling vehicle  304  having an energy source  312  configured as a battery  314  and a BMS  320 , which can be configured to control the charging of (i.e., controlling the flow of current to) the battery  314  via a collector plate  324  coupled to the material handling vehicle  304 . More specifically, collector plate  324  can be configured to receive power from a charging device  330  having a corresponding charging plate  332 , which can be mounted to an adjustable stand  334 . That is, when the collector plate  324  and the charging device  330  are aligned, the BMS  320  can wirelessly communicate with a charge controller  344  of the charging device  330  to charge the battery  314 . 
     To align the collector plate  324  and the charging plate  332 , the BMS  320  can be further configured to communicate with a position compensation system  346 . More specifically, the position compensation system  346  includes a position controller  348  that can communicate with the BMS  320 , and, in response to input from a sensing array  350 , detect the material handling vehicle  304  and move the charging plate  332  into alignment with the collector plate  324  via a number of actuating structures and/or actuators. 
     In the illustrated non-limiting example, the position compensation system  346  can be configured to move the charging plate  332  along one or more directions, namely, a first direction  352  and a second direction  354 , to account for misalignments in two dimensions. The first direction  352  can be an extension direction that extends between the charging device  330  and the material handling vehicle  304 , to adjust a gap  340  between the collector plate  324  and the charging plate  332 . The second direction  354  can be a vertical direction to adjust a height of the charging plate  332  and generally is oriented perpendicular or normal to a ground surface, or corresponds with a height of the material handling vehicle  304 . In other non-limiting examples, the position compensation system  346  may additionally or alternatively be configured to move the charging plate  332  in a third direction that is perpendicular to both the first direction  352  and the second direction  354  so that it extends along a length of the material handling vehicle  304 . 
     To permit movement along the first direction  352  and the second direction  354 , the stand  334  can include a bracket  360  that can be configured to support the charging plate  332 . The bracket  360  can be operatively coupled with a base  362  (e.g., a stationary portion) by an upper or first arm  364  and a lower or second arm  366  (e.g., that collectively form an extension arm or movable portion with the bracket  360 ) to move relative to the base  362 . In particular, the first arm  364  can be pivotally coupled to an upper end of the bracket  360  at a first bracket connection  368  (e.g., a pinned connection) and the second arm  366  can be pivotally coupled to a lower end of the bracket  360  at a second bracket connection  370  (e.g., a pinned connection). Additionally, the first arm  364  can be pivotally coupled to a first nut  372  (e.g., a threaded nut) that can be configured to engage a lead screw  374 , which can be rotatably coupled with and at least partially disposed within the base  362 , and the second arm  366  is pivotally coupled to a second nut  376  (e.g., a threaded nut) that can be configured to engage the lead screw  374 . The lead screw  374  can be rotated by a motor  380  in response to a command from the position controller  348 . By rotating the lead screw  374 , the position of the bracket  360 , and thus the charging plate  332 , can be adjusted to place the charging plate  332  into alignment with the collector plate  324 . 
     For example, the lead screw  374  can be configured so that when the lead screw  374  is rotated in a first direction, the engagement of the first nut  372  and the second nut  376  with the lead screw  374  can cause the bracket  360  and the charging plate  332  to move closer to (i.e., toward) the collector plate  324  along the first direction  352 , reducing the gap  340  therebetween. Accordingly, when the lead screw  374  is rotated in an opposite direction, the bracket  360  and the charging plate  332  can be moved away from the collector plate  324  along the first direction  352 , increasing the size of the gap  340  therebetween. In both cases, the rotation of the lead screw  374  can cause each of the first arm  364  and the second arm  366  to rotate about the first bracket connection  368  and the second bracket connection  370 , respectively to move the charging plate  332  along the first direction  352 . 
     Alternatively or additionally, the lead screw  374  can be configured so that when the lead screw  374  is rotated in a first direction, the engagement of the first nut  372  and the second nut  376  with the lead screw  374  can cause the bracket  360  and the charging plate  332  to move upward (i.e., away from the ground) along the second direction  354 , so as to be in alignment with the collector plate  324 . Accordingly, when the lead screw is rotated in an opposite direction, the bracket  360  and the charging plate  332  can be moved downward (i.e., toward the ground) along the second direction  354  to be in alignment with the collector plate  324 . In other non-limiting examples, the first arm  364  and the second arm  366  can be actuated by other methods as known in the art, for example, linear actuators. In this way, each of the first arm  364  and the second arm  366  can also be actuated independently of one another. 
     To ensure alignment between the collector plate  324  and the charging plate  332 , the sensing array  350  can include a position sensor  386  that can be in communication with the position controller  348 . The position sensor  386  can be a proximity sensor that can be configured to send position signals or other types of signals to the position controller  348 , although other types of sensors and configurations of sensors are possible. In response to the signals from the position sensor  386 , the position controller  348  can operate the motor  380  to move the first arm  364  and the second arm  366  via the lead screw  374 , and bring charging plate  332  into alignment with the collector plate  324 . 
     With regard to  FIG.  4   , another non-limiting example of an automatic charging system  400  is illustrated. The automatic charging system  400  is similar to the automatic charging system  100 , with like reference numeral referring to like features, except where otherwise indicated. In particular, the automatic charging system  400  can include a material handling vehicle  404  having an energy source  412  configured as a battery  414  and a BMS  420 , which can be configured to control the charging of (i.e., controlling the flow of current to) the battery  414  via a collector plate  424  coupled to the material handling vehicle  404 . More specifically, collector plate  424  can be configured to receive power from a charging device  430  having a corresponding charging plate  432 , which can be mounted to an adjustable stand  434 . That is, when the collector plate  424  and the charging device  430  are aligned, the BMS  420  can wirelessly communicate with a charge controller  444  of the charging device  430  to charge the battery  414 . 
     To align the collector plate  424  and the charging plate  432 , the BMS  420  can be further configured to communicate with a position compensation system  446 . More specifically, the position compensation system  446  includes a position controller  448  that can communicate with the BMS  420 , and, in response to input from a sensing array  450 , detect the material handling vehicle  404  and move the charging plate  432  into alignment with the collector plate  424  via a number of actuating structures and/or actuators. 
     In the illustrated non-limiting example, the position compensation system  446  can be configured to move the charging plate  432  along an extension or first direction  452 , which can extend between the charging device  430  and the material handling vehicle  404 , to adjust a gap  440  between the collector plate  424  and the charging plate  432 . To permit such movement along each of the first direction  452 , the stand  434  can include a beam  460  that can be configured to moveably support the charging plate  432 . The beam  460  can be operatively coupled to a base  462  (e.g., a stationary portion) via a pantograph  464 , which can allow the beam  460 , and thus the charging plate  432 , to move relative to the base  462  along the first direction  452 . In that regard, the pantograph  464  can act as an extension arm (e.g., a moveable portion) of the position compensation system  446 . 
     More specifically, the base  462  includes a lead screw  466  that can be rotated by a motor  468 , which can be controlled by the position controller  448 , and the pantograph  464  includes a nut  470  that engages with the lead screw  466  to extend and contract the pantograph  464  along the first direction  452 . Thus, for example, when the lead screw  466  is rotated in a first direction, the engagement of the nut  470  with the lead screw  466  causes the pantograph  464  to extend along the first direction  452  to move the charging plate  432  closer to the collector plate  424 , thereby reducing the gap  440 . Conversely, when the lead screw  466  is rotated in a second direction that is opposite the first direction, the engagement of the nut  470  with the lead screw  466  causes the pantograph  464  to contract along the first direction  452  to move the charging plate  432  away from the collector plate  424 , thereby increasing the gap  440 . In other non-limiting examples, the pantograph  464  can be actuated by other methods as known in the art, for example, a linear actuator. 
     To ensure alignment between the collector plate  424  and the charging plate  432 , the sensing array  450  can include a position sensor  486  in communication with the position controller  448 . The position sensor  486  can be configured as a proximity sensor, which can send position signals or other types of signals to the position controller  448 , although other types of sensors can also be used. In response to the signals from the position sensor  486 , the position controller  448  can operate the motor  468  to extend and/or retract the pantograph  464 , thereby bringing the charging plate  432  into alignment with the collector plate  424 . 
     Turning to  FIG.  5   , another non-limiting example of an automatic charging system  500  is illustrated. The automatic charging system  500  is similar to the automatic charging system  400 , with like reference numeral referring to like features, but includes additional structures to allow for movement of a charging pad along three directions. In particular, the automatic charging system  500  can include a material handling vehicle  504  having an energy source  512  configured as a battery  514  and a BMS  520 , which can be configured to control the charging of (i.e., controlling the flow of current to) the battery  514  via a collector plate  524  coupled to the material handling vehicle  504 . More specifically, collector plate  524  can be configured to wirelessly receive power from a charging device  530  having a corresponding charging plate  532 , which is mounted to an adjustable stand  534 . That is, when the collector plate  524  and the charging device  530  are aligned, the BMS  520  can wirelessly communicate with a charge controller  544  of the charging device  530  to charge the battery  514 . 
     To align the collector plate  524  and the charging plate  532 , the BMS  520  can also communicate with a position compensation system  546 . More specifically, the position compensation system  546  includes a position controller  548  that can communicate with the BMS  520 , and, in response to input from a sensing array  550 , detect the material handling vehicle  504  and move the charging plate  532  into alignment with the collector plate  524  via a number of actuating structures and/or actuators. 
     In the illustrated non-limiting example, the position compensation system  546  can be configured to move the charging plate  532  along three directions, namely, a first direction  552 , a second direction  554 , and a third direction  556  to account for misalignments in three dimensions. The first direction  552  can be an extension direction that extends between the charging device  530  and the material handling vehicle  504 , to adjust the gap  540  between the collector plate  524  and the charging plate  532 . The second direction  554  can be a vertical direction to adjust a height of the charging plate  532  relative to the ground and generally corresponds with a height of the material handling vehicle  504 . The third direction  556  can be a lateral direction that extends perpendicular to both the first direction  552  and the second direction  554  so that it extends along a length of the material handling vehicle  504 . 
     Similar to the automatic charging system  400 , the charging plate  532  can be supported by a beam  560  that is moveably coupled to a base  562  by a pantograph  564  (e.g., an extension arm or moveable portion). The position controller  548  can operate a first motor  568  to move the beam  560  and the charging plate  532  along the first direction  552  to adjust the gap  540 . However, in the illustrated non-limiting example, the charging plate  532  can also be moveably coupled with the beam  560  to allow the charging plate  532  to move along the second direction  554 . More specifically, the position controller  548  can operate a second motor  570  to move the charging plate  532  along the second direction  554 . Additionally, the base  562  is moveably coupled with a rail  572  (e.g., a stationary portion) to allow the base  562 , and therefore the pantograph  564 , the beam  560 , and the charging plate  532  to move together along the third direction  556 . The rail  572  can be fixedly coupled to the ground or another stationary structure. Thus, to move the charging plate  532  along the third direction  556 , the position controller  548  can operate a third motor  574  to move the base  562 , the pantograph  564 , the beam  560 , and the charging plate  532  together along the third direction  556 . 
     To ensure alignment between the collector plate  524  and the charging plate  532 , the sensing array  550  can include a first position sensor  586 , a second position sensor  588 , and a third position sensor  590  that are each in communication with the position controller  548 . The sensing array  550 , or a portion thereof (e.g., the third position sensor  590 ) can be coupled to move with the charging plate  532 . The first position sensor  586  can be configured as a proximity sensor to monitor the position of (i.e., align) the charging plate  532  along the first direction  552 . For example, the first position sensor  586  can be configured to measure a distance to the material handling vehicle  104  (i.e., a reflective surface of the material handling vehicle  104 ). This measured distance can be used by the position controller  548  to control movement of the charging plate  532  perpendicularly to the material handling vehicle  104  (i.e., along the first direction  552 ). The second position sensor  588  can be a retroreflective sensor that can be configured to detect a first reflective strip  592  on the material handling vehicle  504  to align the charging plate  532  along the second direction  554 . The third position sensor  590  can be a retroreflective sensor that can be configured to detect a second reflective strip  594  on the material handling vehicle  504  to align the charging plate  532  along the third direction  556 . 
     As illustrated, the first reflective strip  592  can be oriented along the third direction  556  so that the second position sensor  588  can detect the first reflective strip  592  no matter its relative position along the third direction  556 . Similarly, the second reflective strip  594  can be oriented along the second direction  554  so that the third position sensor  590  can detect the second reflective strip  594  no matter its relative position along the second direction  554 . Additionally, the first reflective strip  592  and the second reflective strip  594  can be a known distance from the collector plate  524  to allow the position controller  548  to determine where to position the charging plate  532  so that it is aligned with the collector plate  524 . 
     With additional reference to  FIG.  6   , a method  600  for operating the position compensation system  546  to move the charging plate  532  into alignment with the collector plate  524  is illustrated. While the method  600  is described in relation to the automatic charging system  500 , it will be appreciated by those skilled in the art that such a method can be modified to apply to other non-limiting example charging systems according to the present disclosure. The method  600  may start at step  604 , where the sensing array  550  can detect the presence of the material handling vehicle  504  within a charging area. More specifically, the first position sensor  586  can detect the presence of the material handling vehicle  504  and send a corresponding signal to the position controller  548 . In other non-limiting examples, such a signal can be provided or sent by another means, for example, a central automation server or a push button. It is appreciated that the position compensation system  546  can be in a stored configuration. 
     At step  608 , upon receiving the signal that the material handling vehicle  504  is present, the position controller  548  can position the charging plate  532  in alignment with the collector plate  524 . The step  608  of aligning the charging plate  532  with the collector plate  524  can include operating any or all actuators and/or actuating structures of the position compensation system. For example, with specific reference to  FIG.  7   , the position controller  548  can operate the third motor  574  to move the charging plate  532  along the third direction  556  until the third position sensor  590  is aligned with and detects the second reflective strip  594 . In this way, the charging plate  532  will be in alignment with the collector plate  524  along third direction  556 . Additionally, with specific reference to  FIG.  8   , the position controller  548  can operate the second motor  570  to move the charging plate  532  along the second direction  554  until the second position sensor  588  is aligned with and detects the first reflective strip  592 . In this way, the charging plate  532  will be in alignment with the collector plate  524  along second direction  554 . Furthermore, the position controller  548  can operate the first motor  568  to extend the pantograph  564  and move the charging plate  532  along the first direction  552  until the first position sensor  586  indicates (i.e., sends a signal) that the gap  540  is within the specified tolerance. In this way, the charging plate  532  will be in alignment with the collector plate  524  along first direction  552 . 
     In some cases, it may be preferable to adjust the position of the charging plate  532  along each of the first direction  552 , the second direction  554 , and the third direction  556  in series. For example, the position controller  548  can first adjust the position of the charging plate  532  along the third direction  556  followed by the second direction  554 , and then the third direction  556 . In other non-limiting examples, the position controller  548  can adjust the position of the charging plate  532  along each of the first direction  552 , the second direction  554 , and the third direction  556  in a different order. Additionally, the position controller  548  can adjust the position of the charging plate  532  along any of the first direction  552 , the second direction  554 , and the third direction  556  simultaneously. Moreover, in some cases, it may not be necessary to adjust the position of the charging plate  532  along all directions. For example, the position controller  548  may only adjust the position of the charging plate along the first direction  552 , or along the first direction  552  and the third direction  556 . 
     With continued reference to  FIG.  6   , once the charging plate  532  is aligned with the collector plate  524 , the position controller  548  can communicate with one or both of the BMS  520  and the charge controller  544  to charge the battery  514  at step  630 . Once charging has been completed, the position controller  548  can operate the position compensation system  546  to move the charging plate  532  back to a stored position at step  634 . 
     In some cases, automatic charging systems, as described in accordance with the various non-limiting examples above can be provided as a retrofit kit. In general, such retrofit kits can be used for charging a battery of a material handling vehicle and can include, for example, a charging device (e.g., the charging device  130 ,  230 ,  330 ,  430 ,  530 ). Additionally, a retrofit kit can include a collector plate (e.g., the collector plate  124 ,  224 ,  324 ,  424 ,  524 ). Correspondingly, the retro fit kit may also include a bracket that can be configured to couple the collector plate to the material handling vehicle. Further still, the retrofit kit can include reflective strips or other reflective elements that can be coupled to the material handling vehicle, as may facilitate automatic alignment of the charging system using a retroreflector sensor system in accordance with the description above. 
     For certain types of vehicles there are training requirements imposed by various government agencies, laws, rules, and regulations. For example, OSHA imposes a duty on employers to train and supervise operators of various types of material handling vehicles. Recertification every three years is also required. In certain instances, refresher training in relevant topics shall be provided to the operator when required. In all instances, the operator remains in control of the material handling vehicle during performance of any actions. Further, a warehouse manager remains in control of the fleet of material handling vehicles within the warehouse environment. The training of operators and supervision to be provided by warehouse managers requires among other things proper operational practices including among other things that an operator remain in control of the material handling vehicle, pay attention to the operating environment, and always look in the direction of travel. 
     Within this specification non-limiting examples have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein. Accordingly, aspects of some non-limiting examples may be equally applied or combined with aspects of other non-limiting examples. 
     Thus, while the invention has been described in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein. 
     Various features and advantages of the invention are set forth in the following claims.