Patent Publication Number: US-2023147632-A1

Title: Apparatus and method for arbitrating optical communication between can buses

Description:
FIELD 
     The present invention relates to systems and methods for facilitating wireless optical communication, and more particularly, embodiments concern an apparatus and method for facilitating bidirectional wireless optical communication between independent controller area network buses by arbitrating transmit and receive processes. 
     BACKGROUND 
     Wired controller area network (CAN) buses may be used to facilitate electronic communication between hosts and peripherals. In particular, CAN buses may be used for communication between components within vehicles. Between these components, a two-wire CAN bus may be bidirectionally driven and a dominant bit (low or “0” condition) on the bus line dominates the bus to transmit data from one component to another on the same bus. However, this solution, by itself, is not sufficient to facilitate bidirectional wireless communication between independent CAN buses attempting to transmit simultaneously. 
     This background discussion is intended to provide information related to the present invention which is not necessarily prior art. 
     SUMMARY 
     Embodiments of the present invention address the above-described and other problems and limitations in the prior art by providing an apparatus and method for facilitating bidirectional wireless optical communication between independent CAN buses by arbitrating transmit and receive processes to prevent the CAN buses from transmitting simultaneously across the optical link ends. 
     In one embodiment of the present invention, a system may comprise a mobile device, a charging station, and an arbiter apparatus. The mobile device may include a battery configured to provide power to an electric motor and a battery management system configured to monitor the battery, and the battery management system may be configured to communicate via a first CAN bus having a first optical link end. The charging station may be configured to charge the battery, and the charging station may be configured to communicate via a second CAN bus having a second optical link end. When the mobile device is operationally aligned with the charging station for charging the battery, the first and second CAN buses may be operationally aligned and configured to allow for bidirectional optical communication across the first and second optical link ends between the battery management system and the charging station regarding charging the battery. The arbiter apparatus may be operationally interposed between the first and second optical link ends and configured to arbitrate the bidirectional optical communication via the first and second optical link ends by delaying a subsequent optical communication from one of the battery management system and the charging station until a prior optical communication from an other of the battery management system and the charging station has concluded. 
     In another embodiment of the present invention, a system may be provided for arbitrating bidirectional optical communication between a mobile device and a charging station. The mobile device may include a battery configured to provide power to an electric motor and a battery management system configured to monitor the battery, and the battery management system may be configured to communicate via a first CAN bus having a first optical link end. The charging station may be configured to charge the battery, and the charging station may be configured to communicate via a second CAN bus having a second optical link end. When the mobile device is operationally aligned with the charging station for charging the battery, the first and second CAN buses may be operationally aligned and configured to allow for bidirectional optical communication across the first and second optical link ends between the battery management system and the charging station regarding charging the battery. The system may comprise an arbiter apparatus operationally interposed between the first and second optical link ends and configured to arbitrate the bidirectional optical communication via the first and second optical link ends by delaying a subsequent optical communication from one of the battery management system and the charging station until a prior optical communication from an other of the battery management system and the charging station has concluded. 
     In another embodiment of the present invention, a method may be provided for arbitrating bidirectional optical communication between a mobile device and a charging station. The mobile device may include a battery configured to provide power to an electric motor and a battery management system configured to monitor the battery, and the battery management system may be configured to communicate via a first CAN bus having a first optical link end. The charging station may be configured to charge the battery, and the charging station may be configured to communicate via a second CAN bus having a second optical link end. When the mobile device is operationally aligned with the charging station for charging the battery, the first and second CAN buses may be operationally aligned and configured to allow for bidirectional optical communication across the first and second optical link ends between the battery management system and the charging station regarding charging the battery. The method may comprise interposing an arbiter apparatus between the first and second optical link ends and arbitrating with the arbiter the bidirectional optical communication via the first and second optical link ends by delaying a subsequent optical communication from one of the battery management system and the charging station until a prior optical communication from an other of the battery management system and the charging station has concluded. 
     Various implementations of the foregoing embodiments may include any one or more of the following features. The mobile device may be an automated guided vehicle or an autonomous mobile robot. The bidirectional optical communication between the battery management system and the charging station may concern optimizing power delivery to the battery. The arbiter apparatus may prevent the subsequent optical communication from the one of the battery management system and the charging station from proceeding until a dominant bit of the prior optical communication from the other of the battery management system and the charging station is released, thereby preventing the first and second CAN buses from transmitting simultaneously across the first and second optical link ends. 
     The mobile device may include a collector, the first optical link end may be part of the collector, and the first optical link end may include a first transmit light emitting diode and a first receive photodiode. The charging station may include a base configured to cooperate with the collector to charge the battery, the second optical link end may be part of the base, and the second optical link end may include a second transmit light emitting diode and a second receive photodiode. The mobile device may move to the charging station such that the collector is proximate to the base and the first optical link end is aligned with the second optical link end. 
     The collector may include one or more electrical contact pads, which are extendable to make electrical contact with the base and retractable to break electrical contact with the base, and at least one collector magnet, and the base may include at least one base magnet. When the mobile device moves to the charging station such that the collector magnet is proximate to the base magnet the one or more electrical contact pads may extend for charging the battery, and when the mobile device moves away from the charging station such that the collector magnet is no longer proximate to the base magnet the one or more electrical contact pads may retract. 
     This summary is not intended to identify essential features of the present invention, and is not intended to be used to limit the scope of the claims. These and other aspects of the present invention are described below in greater detail. 
    
    
     
       DRAWINGS 
       Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein: 
         FIG.  1    is a high-level block diagram of components in an embodiment of a system for arbitrating bidirectional optical communication between a mobile device and a charging station; 
         FIG.  2    is a bottom view of an implementation of a collector component of the mobile device of  FIG.  1   ; 
         FIG.  3    is a plan view of an implementation of a base component of the charging station of  FIG.  1   ; 
         FIG.  4    is a fragmentary side elevation view showing the collector of  FIG.  2    and the base of  FIG.  3    operationally aligned for charging, wherein such alignment also operationally aligns and thereby facilitates the bidirectional optical communication of the system of  FIG.  1   ; and 
         FIG.  5    is a flowchart of steps in an embodiment of a method for arbitrating bidirectional optical communication between a mobile device and a charging station, wherein the method may reflect operation of the system of  FIG.  1   . 
     
    
    
     The figures are not intended to limit the present invention to the specific embodiments they depict. The drawings are not necessarily to scale. 
     DETAILED DESCRIPTION 
     The following detailed description of embodiments of the invention references the accompanying figures. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those with ordinary skill in the art to practice the invention. The embodiments of the invention are illustrated by way of example and not by way of limitation. Other embodiments may be utilized and changes may be made without departing from the scope of the claims. The following description is, therefore, not limiting. The scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled. 
     In this description, references to “one embodiment,” “an embodiment,” or “embodiments” mean that the feature or features referred to are included in at least one embodiment of the invention. Separate references to “one embodiment,” “an embodiment,” or “embodiments” in this description do not necessarily refer to the same embodiment and are not mutually exclusive unless so stated. Specifically, a feature, component, action, step, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, particular implementations of the present invention can include a variety of combinations and/or integrations of the embodiments described herein. 
     Broadly characterized, embodiments of the present invention provide an apparatus and method for facilitating bidirectional wireless optical communication between independent CAN buses by arbitrating transmit and receive processes to prevent the CAN buses from transmitting simultaneously across the optical link ends. Bidirectional transmission between independent CAN buses over an infrared (IR) wireless optical link with a clear air gap between the link ends can result in a bus conflict if both CAN buses attempt to transmit simultaneously. Embodiments of the arbiter apparatus and method of the present invention avoid this conflict by determining that one side is transmitting and blocking the dominant bit in the other direction, which causes the receiving side to wait until the transmitting side finishes transmitting and releases control of the bus. Once control is released, the arbiter recognizes the dominant bit from the other direction and allows it to transmit. 
     Potential applications include facilitating communication between a battery management system (BMS) and a battery charger, a robot or other automated guided vehicle and a computer, and a robot or other automated guided vehicle and a remote device. In one implementation involving communication between a robot BMS having a first CAN bus and a battery charging station having a second CAN bus, the charging station may include the arbiter circuit to mediate CAN bus exchanges up to two hundred fifty kilobytes-per-second over a twenty millimeter air gap regarding such relevant information as optimizing power delivery. 
     Referring to  FIGS.  1 - 4   , an embodiment of a system  10  is shown including an arbiter apparatus  12  which may be physically and operationally configured to arbitrate optical CAN bus communication between a mobile device  14  powered by a battery  16  and a battery charging station  18  for charging the battery  16 . 
     Referring particularly to  FIG.  1   , the mobile device  14  may include the battery  16 , an electric motor (not shown) powered by the battery  16 , a battery management system  22  configured to monitor the battery  16 , and a first CAN bus  24 . In various implementations, the mobile device  14  may be an automated guided vehicle or an autonomous mobile robot. 
     Referring also to  FIG.  2   , the mobile device  14  may further include a collector  26  mounted on or otherwise incorporated into a surface of the mobile device  14 . In one implementation, the collector  26  may include one or more electrical contact pads  28 A, 28 B which are extendable and retractable, may include a collector center magnet  30  and collector entry and exit magnets  32 A, 32 B, and may be communicatively coupled with the BMS  22  by the first CAN bus  24 . 
     The first CAN bus  24  may include a first CAN transceiver  36  and a first optical link end  38  including a first set of transmit IR light emitting diodes (LEDs)  40  located behind a first collector optical window, and a first receive PIN photodiode  42  located behind a second collector optical window. The first optical link end  38  may be mounted on or incorporated into the collector  26 . 
     The charging station  18  may be configured to charge the battery  16  of the mobile device  14 , and may include a battery charger  46  and a second CAN bus  48 . Referring also to  FIG.  3   , the charging station  18  may further include a base  50  mounted on or otherwise incorporated into a horizontal or vertical non-conductive surface over, against, or under which the mobile device  14  may move, and may be physically and operationally configured to cooperate with the collector  14  to charge the battery  16  aboard the mobile device  14 . In one implementation, the base  50  may include a base center magnet  52  and base entry and exit magnets  54 A, 54 B, and may be communicatively coupled with the battery charger  46  by the second CAN bus  48 . 
     The second CAN bus  48  may include a second CAN transceiver  56  and a second optical link end  58  including a second set of transmit IR light emitting diodes (LEDs)  60  located behind a first base optical window, and a second receive PIN photodiode  62  located behind a second base optical window. The second optical link end  58  may be mounted on or incorporated into the base  50 . 
     In one implementation, when the mobile device  14  moves to the charging station  18  such that the collector center magnet  30  is proximate to the base center magnet  52  the one or more electrical contact pads  28 A, 28 B may extend to make electrical contact with the base  50  for charging the battery  16 . Further, when the mobile device  14  moves away from the charging station  18  such that the collector center magnet  30  is no longer proximate to the base center magnet  52 , the one or more electrical contact pads  28 A, 28 B retract to break electrical contact with the base  50 . 
     In one implementation, shown in  FIG.  4   , when the mobile device  14  moves to the charging station  18  such that the collector  26  is proximate to and operationally aligned with the base  50  for charging, the first optical link end  38  is aligned with the second optical link end  58 . More specifically, the collector transmitter  40  is operationally aligned with the base receiver  62  for communication from the collector  26  to the base  50 , and the base transmitter  60  is operationally aligned with the collector receiver  42  for communication from the base  50  to the collector  26 . The first and second CAN buses  24 , 48  are configured to allow for bidirectional optical communication across the operationally aligned first and second optical link ends  38 , 58  between the BMS  22  and the charging station  18  regarding charging the battery. Such communication may include, for example, optimizing power delivery to the battery  16 . 
     The arbiter apparatus  12  may be physically and operationally configured to facilitate wireless optical communication across the air gap between the CAN buses  38 , 58  by arbitrating the bidirectional optical communication such that a subsequent optical communication from one of the BMS  22  or the charging station  18  cannot proceed until a prior optical communication from the other has concluded. In one implementation, the arbiter apparatus  12  may be located in, on, or otherwise associated with the base  50  and operationally interposed between the two optical link ends  38 , 58 . 
     In one implementation, the arbiter apparatus  12  prevents the subsequent optical communication from the one of the BMS  22  and the charging station  18  from proceeding until a dominant bit of the prior optical communication from the other is released, thereby preventing the first and second CAN buses  24 , 48  from attempting to simultaneously transmit across the first and second optical link ends  38 , 58 . 
     Other embodiments and implementations of the system  10  may include more, fewer, or alternative components and/or perform more, fewer, or alternative actions, including those discussed elsewhere herein, and particularly those discussed in the following section describing the method  110 . 
     Referring also to  FIG.  5   , an embodiment is shown of a method  110  for arbitrating bidirectional optical communication between the mobile device  14  and the charging station  18 . The method  110  may reflect operation of the system  10  and may be implemented using components of the system  10  described above and shown in  FIGS.  1 - 4   . 
     As the mobile device  14  moves over, under, or against the base  18 , as shown in step  112 , when the collector center magnet  30  aligns with the base center magnet  52 , the center magnets attract each other and cause the electrical contact pads  28 A, 28 B of the collector  26  to quickly (˜20 ms) extend and make electrical contact with the base  50  for charging, as shown in step  114 . 
     In one implementation, a sensor in the electrical contact pads  28 A, 28 B may determine when the pads  28 A, 28 B are properly positioned relative to the base  50  of the charging station  18  for charging. Additionally or alternatively, a Hall effect sensor may be associated with the electrical contact pads  28 A, 28 B and may change state when the pads  28 A, 28 B extend or retract and thereby indicate when the pads  28 A, 28 B are extended or retracted. Thus, by detecting the charge voltage directly and/or by monitoring the Hall effect sensor in the electrical contact pads  28 A, 28 B, the mobile device  14  can determine when it is in proper position relative to the base  50  of the charging station  18  for charging, as shown in step  116 . 
     When the collector  26  is properly aligned with the base  50  for charging, the first optical link  38  of the first CAN bus  24  is properly aligned with the second optical link  58  of the second CAN bus  48  for wireless optical communication, as shown in step  118 . 
     Current flows to the battery to charge it, as shown in step  120 . 
     The arbiter apparatus  12  and method facilitates bidirectional wireless optical communication via the CAN buses  24 , 48  between the BMS  22  and the charging station  18  by arbitrating transmit and receive processes, as shown in step  122 . In particular, if the BMS  22  or charging station  18  is transmitting, the arbiter apparatus  12  prevents the other from starting a subsequent transmission until the prior transmission has concluded, as shown in step  124 . 
     The BMS  22  and the charging station  18  may exchange commands and information during charging in order to, for example, optimize power delivery (for example, to throttle the current as a function of the battery&#39;s charge and/or temperature), as facilitated by the arbiter apparatus  12  operationally interposed between the optical link ends  38 , 58 , as shown in step  126 . 
     When charging is complete, current to the battery  16  is stopped, as shown in step  128 . 
     As the mobile device  14  moves away from the base  50 , as shown in step  130 , when the collector entry and exit magnets  32 A, 32 B align with the base entry and exit magnets  54 A, 54 B, they repel each other and cause the electrical contact pads  28 A, 28 B of the collector  26  to quickly (˜20 ms) retract away from and break electrical contact with the base  50 , as shown in step  132 . This quick extension and retraction minimizes potentially damaging arcing which could otherwise occur. 
     Other embodiments and implementations of the method  110  may include more, fewer, or alternative steps and/or involve more, fewer, or alternative components, including those discussed elsewhere herein and particularly those discussed in the preceding section describing the system  10 . 
     Although the invention has been described with reference to the one or more embodiments illustrated in the figures, it is understood that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims. 
     Having thus described one or more embodiments of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following: