Patent Publication Number: US-2016229432-A1

Title: Communication System And Method Of A Vehicle Consist

Description:
FIELD 
     Embodiments of the inventive subject matter described herein relate to communications between vehicles in a vehicle consist. 
     BACKGROUND 
     Some known vehicle consists include several propulsion-generating vehicles that generate tractive effort for propelling the vehicle consists along a route. For example, trains may have several locomotives coupled with each other that propel the train along a track. The locomotives may communicate with each other in order to coordinate the tractive efforts and/or braking efforts provided by the locomotives. As one example, locomotives may be provided in a distributed power (DP) arrangement with one locomotive designated as a lead locomotive and other locomotives designated as remote locomotives. The lead locomotive may direct the tractive and braking efforts provided by the remote locomotives during a trip of the consist. 
     Some known consists use wireless communication between the locomotives for coordinating the tractive and/or braking efforts. For example, a lead locomotive can issue commands to the remote locomotives. The remote locomotives receive the commands and implement the tractive efforts and/or braking efforts directed by the commands. 
     Before the remote vehicles will operate according to command messages received from a lead locomotive, however, communication links between the lead locomotive and the remote locomotive may need to be established. A communication “handshake” between the lead and remote locomotives may need to occur so that the remote locomotives can identify the lead locomotive, the lead locomotive can identify the remote locomotives, and the remote locomotives can determine that forthcoming command messages are received from the lead locomotive and not from another locomotive. In order to establish the communication links used to remotely control the remote locomotives from the lead locomotive, some known systems require an operator to go onboard each of the remote locomotives, manually input information about the lead locomotive and/or remote locomotives, and initiate communication of one or more wireless messages from the remote locomotives to the lead locomotive. In some vehicle consists having many remote locomotives, requiring an operator to enter onboard and manually enter this type of information onboard each remote locomotive can be very time-consuming and susceptible to human errors in entering the correct information. As a result, considerable time and effort may be expended in establishing communication links between the lead and remote locomotives in a vehicle consist. 
     BRIEF DESCRIPTION 
     In one embodiment, a method (e.g., for communicatively linking vehicles in a vehicle consist) includes determining a vehicle identifier for a first remote vehicle included in a vehicle consist formed from a lead vehicle and at least the first remote vehicle, communicating a wireless linking message addressed to the vehicle identifier from the lead vehicle to the first remote vehicle, and establishing a communication link between the lead vehicle and the first remote vehicle responsive to receipt of the wireless linking message at the first remote vehicle. The communication link can be established such that movement of the first remote vehicle is remotely controlled from the lead vehicle via the communication link. The communication link can be established without an operator entering the first remote vehicle. 
     In another embodiment, a system (e.g., a communication system) includes a control unit and a communication unit. The control unit can be configured to determine a vehicle identifier for a first remote vehicle included in a vehicle consist formed from a lead vehicle and at least the first remote vehicle. The communication unit can be configured to communicate a wireless linking message addressed to the vehicle identifier from the lead vehicle to the first remote vehicle. The communication unit also can be configured to establish a communication link between the lead vehicle and the first remote vehicle responsive to receipt of the wireless linking message at the first remote vehicle. The control unit can be configured to remotely control movement of the first remote vehicle from the lead vehicle via the communication link. The communication link can be established without an operator entering the first remote vehicle. 
     In another embodiment, a method (e.g., for communicatively linking vehicles in a vehicle consist) includes receiving unique vehicle identifiers of remote vehicles included in a vehicle consist with a lead vehicle, communicating linking messages with the unique vehicle identifiers to the remote vehicles, and responsive to the unique vehicle identifiers in the linking messages matching the remote vehicles in the vehicle consist, establishing one or more communication links between the lead vehicle and the remote vehicles to permit the lead vehicle to remotely control movement of the remote vehicles included in the vehicle consist. The one or more communication links are established without an operator being onboard the remote vehicles to communicate responsive messages from the remote vehicles to the lead vehicle. 
     In another embodiment, a method (e.g., for communicatively linking vehicles in a vehicle consist) includes determining a first unique vehicle identifier for a first remote vehicle and a second unique vehicle identifier for a second remote vehicle included in a vehicle consist formed from a lead vehicle, the first remote vehicle, and the second remote vehicle, detecting a single instance of an operator actuating an input device onboard the lead vehicle, communicating from the lead vehicle a first wireless linking message addressed to the first unique vehicle identifier to the first remote vehicle and communicating a second wireless linking message addressed to the second unique vehicle identifier to the second remote vehicle responsive to detecting the single instance of the operator actuating the input device, establishing a first communication link between the lead vehicle and the first remote vehicle responsive to receipt of the first wireless linking message at the first remote vehicle and a second communication link between the lead vehicle and the second remote vehicle responsive to receipt of the second wireless linking message at the second remote vehicle (where the communication link is established without an operator entering the first remote vehicle or the second remote vehicle), and remotely controlling movement of the first remote vehicle and the second remote vehicle from the lead vehicle via the first communication link and the second communication link, respectively. Communicating the wireless linking message can include broadcasting the first wireless linking message and the second wireless linking message such that the first remote vehicle receives the first wireless linking message and the second remote vehicle receives the second wireless linking message and at least one other remote vehicle that is located within a wireless communication range of the lead vehicle but that is not included in the vehicle consist receives at least one of the first wireless linking message or the second wireless linking message. Establishing the first communication link between the lead vehicle and the first remote vehicle and the second communication link between the lead vehicle and the second remote vehicle can include preventing the at least one other remote vehicle from establishing a communication link with the lead vehicle based at least in part on the first unique vehicle identifier or the second unique vehicle identifier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is now made briefly to the accompanying drawings, in which: 
         FIG. 1  illustrates one embodiment of a communication system of a vehicle consist or vehicle system; 
         FIG. 2  illustrates a flowchart of one embodiment of a method for communicatively linking vehicles in a vehicle consist; 
         FIG. 3  is a schematic diagram of a propulsion-generating vehicle in accordance with one embodiment; and 
         FIG. 4  illustrates several vehicles located on neighboring routes according to one example. 
     
    
    
     DETAILED DESCRIPTION 
     One or more embodiments of the inventive subject matter described herein provides for methods and systems for communicating between propulsion-generating vehicles in a vehicle consist. This subject matter may be used in connection with rail vehicles and rail vehicle consists, or alternatively may be used with other types of vehicles. The vehicle consist can include two or more vehicles mechanically coupled with each other to travel along a route together. Optionally, the vehicle consist can include two or more vehicles that are not mechanically coupled with each other, but the travel along a route together. For example, two or more automobiles may wirelessly communicate with each other as the vehicles travel along the route in order to coordinate movements with each other. 
     In operation, a lead vehicle can obtain unique vehicle identifiers associated with the remote vehicles included in the same vehicle consist as the lead vehicle. These vehicle identifiers may not include identifiers associated with remote vehicles that are not included in the vehicle consist. The vehicle identifiers may be obtained from a system such as a vehicle control system that restricts movement of vehicle consists based on locations of the vehicle consists. For example, such a system may include a positive train control (PTC) system. Optionally, the vehicle identifiers may be obtained from an energy management system, such as a system that creates a trip plan that designates operational settings of the vehicle consist as a function of time and/or distance along a route to control movement of the vehicle consist. Additionally or alternatively, the vehicle identifiers of the remote vehicles in the vehicle consist may be manually input by an operator or obtained from another system. 
     The lead vehicle can communicate wireless linking messages to the remote vehicles. These linking messages may be addressed to the remote vehicles using the vehicle identifiers. For example, the linking messages may include the vehicle identifiers. Vehicles that receive the linking messages other than the remote vehicles in the consist may not be linked with the lead vehicle due to the vehicle identifiers not matching or being associated with these other vehicles. At the remote vehicles that are included in the vehicle consist, the remote vehicles may be communicatively linked with the lead vehicle. For example, the remote vehicles may communicate linking confirmation messages responsive to receiving the linking messages. 
     The remote vehicles can communicate these confirmation messages without an operator having to enter onboard the remote vehicles. For example, while an operator may be onboard the lead vehicle, the operator may not enter onboard any other vehicles in the vehicle consists in order to establish communication links between the lead and remote vehicles in the vehicle consists. Upon receiving the confirmation messages at the lead vehicle, communication links between the lead and remote vehicles are established. Establishing these communication links allows for the lead vehicle to remotely control operations of the remote vehicles during movement of the vehicle consists along the route. For example, the lead vehicle can communicate wireless command messages to change throttle settings, brake settings, speeds, power outputs, or the like of the remote vehicles during movement of the vehicle consists. Other vehicles that do not have communication links established with the lead vehicle cannot be remotely controlled by the lead vehicle. 
       FIG. 1  illustrates one embodiment of a communication system  100  of a vehicle consist or vehicle system  102 . The illustrated vehicle consist  102  includes propulsion-generating vehicles  104 ,  106  (e.g., vehicles  104 ,  106 A,  106 B,  106 C) and non-propulsion-generating vehicles  108  (e.g., vehicles  108 A,  108 B) that travel together along a route  110 . Although the vehicles  104 ,  106 ,  108  are shown as being mechanically coupled with each other, optionally, the vehicles  104 ,  106 ,  108  may not be mechanically coupled with each other. 
     The propulsion-generating vehicles  104 ,  106  are shown as locomotives, the non-propulsion-generating vehicles  108  are shown as rail cars, and the vehicle consist  102  is shown as a train in the illustrated embodiment. Alternatively, the vehicles  104 ,  106  may represent other vehicles, such as automobiles, marine vessels, or the like, and the vehicle consist  102  can represent a grouping or coupling of these other vehicles. The number and arrangement of the vehicles  104 ,  106 ,  108  in the vehicle consist  102  are provided as one example and are not intended as limitations on all embodiments of the subject matter described herein. 
     In one embodiment, the group of vehicles  104 ,  106 ,  108  may be referred to as a vehicle system, with groups of one or more adjacent or neighboring propulsion-generating vehicles  104  and/or  106  being referred to as a vehicle consist. For example the vehicles  104 ,  106 A,  106 B,  108 A,  108 B, and  106 C may be referred to as a vehicle system with vehicles  104 ,  106 A,  106 B be referred to as a first vehicle consist of the vehicle system and the vehicle  106 C referred to as a second vehicle consist in the vehicle system. Alternatively, the vehicle consists may be defined as the vehicles that are adjacent or neighboring to each other, such as a vehicle consist defined by the vehicles  104 ,  106 A,  106 B,  108 A,  108 B,  106 C. 
     The propulsion-generating vehicles  104 ,  106  can be arranged in a distributed power (DP) arrangement. For example, the propulsion-generating vehicles  104 ,  106  can include a lead vehicle  104  that issues command messages to the other propulsion-generating vehicles  106 A,  106 B,  106 C which are referred to herein as remote vehicles. The designations “lead” and “remote” are not intended to denote spatial locations of the propulsion-generating vehicles  104 ,  106  in the vehicle consist  102 , but instead are used to indicate which propulsion-generating vehicle  104 ,  106  is communicating (e.g., transmitting, broadcasting, or a combination of transmitting and broadcasting) command messages and which propulsion-generating vehicles  104 ,  106  are being remotely controlled using the command messages. For example, the lead vehicle  104  may or may not be disposed at the front end of the vehicle consist  102  (e.g., along a direction of travel of the vehicle consist  102 ). Additionally, the remote vehicles  106 A-C need not be separated from the lead vehicle  104 . For example, a remote vehicle  106 A-C may be directly coupled with the lead vehicle  104  or may be separated from the lead vehicle  104  by one or more other remote vehicles  106 A-C and/or non-propulsion-generating vehicles  108 . 
     The command messages may include directives that direct operations of the remote vehicles. These directives can include propulsion commands that direct propulsion subsystems of the remote vehicles to move at a designated speed and/or power level, brake commands that direct the remote vehicles to apply brakes at a designated level, and/or other commands. The lead vehicle  104  issues the command messages to coordinate the tractive efforts and/or braking efforts provided by the propulsion-generating vehicles  104 ,  106  in order to propel the vehicle consist  102  along a route  110 , such as a track, road, waterway, or the like. 
     The command messages can be communicated using the communication system  100 . In one embodiment, the command messages are wirelessly communicated using the communication system  100 . The communication system  100  may include wireless transceiving hardware and circuitry disposed onboard two or more of the vehicles  104 ,  106 . Prior to the remote vehicles being remotely controlled by a lead vehicle in the vehicle consists, communication links may be established between the lead and remote vehicles. 
     In order to establish a communication link between a lead vehicle and a remote vehicle, the lead vehicle may wirelessly communicate a linking message to the remote vehicle. This linking message may include a unique code, such as a unique vehicle identifier, that is associated with the remote vehicle. This code may not be associated with or otherwise identify other remote vehicles in one embodiment. Alternatively, the vehicle identifier may identify or be associated with two or more remote vehicles, such as two or more remote vehicles that are the same type of vehicle, there included in the vehicle consists, or the like. At the remote vehicle that receives linking message, if the vehicle identifier in the linking message matches, is associated with, or otherwise identifies the remote vehicle, then the remote vehicle may communicate a confirmation message back to the lead vehicle. This confirmation message may be wirelessly communicated to the lead vehicle. The communication link between the lead and remote vehicles may be established responsive to the linking message being received by the remote vehicle and a confirmation message being received by the lead vehicle. Alternatively, the communication link between the lead and remote vehicles may be established once the linking message is received at the remote vehicles, without requiring a confirmation message from being received back at the lead vehicle. 
     The lead vehicle may determine vehicle identifiers for the remote vehicles by receiving a list of unique identifying codes associated with the remote vehicles in the vehicle consist. This list may be received from one or more systems other than the communication system  100 , such as a vehicle control system that restricts movement of the vehicle consists based at least in part on the location of the vehicle consists. One example of such a vehicle control system includes a positive train control or PTC system. Another example of such a system may include an energy management system that creates a trip plan to control movement of the vehicle consist. The trip plan can designate operational settings of the vehicle consist as a function of time and/or distance along the route. The operational settings designated by the trip plan can reduce fuel consumed and/or emissions generated by the vehicle consist relative to the vehicle consist traveling according to other operational settings. Alternatively, the vehicle identifiers may be received from another type of system, such as a dispatch facility, a vehicle yard such as a rail yard, or the like. In one aspect, and operator may manually input the vehicle identifiers onboard the lead vehicle. 
     In contrast to some known systems, operators are not required to enter onboard the remote vehicles to identify these remote vehicles to the lead vehicle. Instead, the remote vehicles are identified by a separate system such that the operators do not need to enter onboard the remote vehicles in order to determine which remote vehicles are in the vehicle consist. As a result, communication links between the lead and remote vehicles may be established without requiring operators to enter onboard the remote vehicles. Consequently, considerable time and effort can be saved by avoiding requiring the operators to enter onboard the remote vehicles. 
       FIG. 2  illustrates a flowchart of one embodiment of a method  200  for communicatively linking vehicles in a vehicle consist. The method  200  may be performed by communication system  100  shown in  FIG. 1 . At  202 , the vehicle identifiers of remote vehicles included in the vehicle consist are obtained. The vehicle identifiers may be obtained from a system other than the communication system, such as a vehicle control system, energy management system, a dispatch facility, or the like. Optionally, the vehicle identifiers may be input by an operator onboard the lead vehicle. The vehicle identifiers that are obtained may be unique codes that uniquely identify the remote vehicles included in the vehicle consist, and that do not include vehicles that are not included in the vehicle consist. For example, the vehicles that are included in the vehicle consist may already be mechanically linked and/or otherwise positioned near one another to travel together along the route as a consist. The vehicle identifiers that are obtained may represent those vehicles in the consist, and not any vehicles not included in the consist. 
     At  204 , a determination is made as to whether or not an input device onboard the lead vehicle of the vehicle consists has been actuated. For example, a determination may be made as to whether or not an operator has pressed a button, flip the switch, moved a lever, typed on a keyboard, touched a touch-sensitive display screen, spoken commands into a microphone, or the like. Actuation of an input device may indicate that the operator wishes to initiate establishment of the communication links between the lead and remote vehicles in the consist. For example, once the vehicle identifiers of the remote vehicles in the consist have been obtained, the operator onboard lead vehicle can press a single button (or otherwise perform a single actuation of an input device) to initiate the establishment of communication links between the lead and remote vehicles. Alternatively, the operator may actuate the same input device several times and/or may actuate multiple input devices to cause the linking messages to be sent. If the input device has been actuated, flow of the method  200  can continue to  206 . On the other hand, if the input device is not actuated, then flow of the method  200  can proceed to  210 , described below. 
     At  206 , linking messages are communicated to the remote vehicles in the consist. These linking messages may be wirelessly communicated from the lead vehicle to the remote vehicles. Linking messages may be addressed to the remote vehicles. For example, the linking messages may include the vehicle identifiers of the remote vehicles included in the consist. Different linking messages may be communicated to different remote vehicles. For example, a first linking message having a first vehicle identifier may be communicated to a first remote vehicle, a second linking message having a different, second vehicle identifier may be communicated to a different, second remote vehicle, and so on. Optionally, one or more linking messages may include multiple vehicle identifiers. For example, a linking message may be wirelessly communicated from the lead vehicle and may include the vehicle identifiers of the remote vehicles included in the vehicle consist. 
     Onboard the remote vehicles, if a linking message is received that includes a vehicle identifier that matches or otherwise corresponds with the remote vehicle receiving the linking message, the remote vehicle may communicate a linking confirmation message back to the lead vehicle. This confirmation message may be wirelessly communicated to the lead vehicle to indicate or confirm receipt of the linking message. The linking confirmation messages may be communicated from the remote vehicles to lead vehicles without operators having to go onboard the remote vehicles. For example, responsive to a remote vehicle receiving a linking message from the lead vehicle that includes the vehicle identifier of the remote vehicle, the remote vehicle may autonomously (e.g., without operator intervention) wirelessly communicate the linking confirmation message to lead vehicle. Alternatively, the remote vehicles may not communicate a linking confirmation message responsive to receiving the linking message. 
     At  208 , a determination is made as to whether or not a linking confirmation message is received at the lead vehicle from one or more of the remote vehicles in the vehicle consist. For example, the lead vehicle may determine if all remote vehicles included in the vehicle consist communicated linking confirmation messages responsive to communicating the linking messages. Receipt of the linking confirmation messages from all remote vehicles at the lead vehicle can indicate or confirm that the remote vehicles received the linking messages from the lead vehicle. Failure to receive linking confirmation messages or an absence of linking confirmation messages from all remote vehicles at the lead vehicle can indicate that one or more remote vehicles did not receive linking messages from the lead vehicle. In one aspect, the lead vehicle may re-communicate one or more additional linking messages to the remote vehicles from which the lead vehicle did not receive a linking confirmation message. 
     If it is determined that linking confirmation messages were received from all remote vehicles, then flow of the method can proceed to  212 . Alternatively, if linking confirmation messages were not received from the remote vehicles, then flow the method  200  can proceed to  210 . 
     At  210 , communication linking between the lead and remote vehicles is prevented. For example, if the remote vehicles did not receive the linking messages, if the lead vehicle did not receive confirmation of receipt of the linking messages at the remote vehicles, and/or if an operator did not actuate any input device to initiate establishment of communication links between the lead and remote vehicles, the communication links between the lead vehicle and one or more remote vehicles may not be established. This can prevent communication links from being established between the lead and remote vehicles that are not included in the vehicle consist, prevent communication links from being established between the lead vehicle and remote vehicle that did not receive a linking message, and/or prevent communication links from being established between vehicles in the vehicle consist without the operator initiating formation of the communication links. 
     At  212 , communication links between the lead vehicle and the remote vehicles are established. These communication links allow for the lead vehicle to remotely control operations and movement of the remote vehicles. For example, the communication links can allow the lead vehicle to issue command messages to the remote vehicles. The command messages may direct the remote vehicles to change throttle settings, brake settings, accelerations, speeds, power outputs, or the like. Upon receipt of the command messages, the remote vehicles may implement the changes in operational settings dictated by the command messages. 
     A communication link may be established by the lead vehicle identifying which remote vehicles are included in the vehicle consist, communicating linking messages to those remote vehicles, and receiving confirmation that the linking messages are received at the remote vehicles. The failure of the lead vehicle to determine which remote vehicles are included in the vehicle consist, the failure of the lead vehicle to communicate linking messages to those remote vehicles, or the failure of lead vehicle to receive confirmation that linking messages were received at the remote vehicles can prevent communication links from being established between the lead and remote vehicles. Alternatively, the communication links may be established by the lead vehicle identifying which remote vehicles are included in the vehicle consist and communicating linking messages to those remote vehicles, regardless of whether or not confirmation that the linking messages were received remote vehicles is received lead vehicle. For example, the communication links may be established without the remote vehicles communicating linking confirmation messages and/or without the lead vehicle receiving linking confirmation messages. 
     A communication link may be defined by a communication handshake between lead and remote vehicles. For example, communication of a first message from a lead vehicle to remote vehicle (e.g., a linking message) followed by successful communication of a second message from the remote vehicle to lead vehicle (e.g., a linking confirmation message) may be a communication handshake that establishes a communication link. Optionally, the communication link may be established by a dedicated communications channel being used between the lead and remote vehicles. For example, a designated frequency or frequency band may define a communication link. 
     The communication links between the lead and remote vehicles may be established without an operator having to go onboard the remote vehicles. As described above, the operator may go onboard the lead vehicle and, once the lead vehicle has determined which remote vehicles are included in the vehicle consist, the lead vehicle may establish communication links with the remote vehicles without the operator or other operators having to go onboard the remote vehicles to communicate information from the remote vehicles to the lead vehicle. As a result, considerable time and effort may be saved in setting up a vehicle consist for travel. 
       FIG. 3  is a schematic diagram of a propulsion-generating vehicle  400  in accordance with one embodiment. The vehicle  400  may represent one or more of the vehicles  104 ,  106  shown in  FIG. 1 . The communication system  100  shown in  FIG. 1  may include one or more components onboard the vehicle  400  that are used to establish communication links between the vehicle  400  and one or more other vehicles in the same vehicle consist. 
     The vehicle  400  includes a control unit  402  that controls operations of the vehicle  400 . The control unit  402  can include or represent one or more hardware circuits or circuitry that include, are connected with, or that both include and are connected with one or more processors, controllers, or other hardware logic-based devices. The control unit  402  is connected with an input device  404  and an output device  406 . The control unit  402  can receive manual input from an operator of the propulsion-generating vehicle  400  through the input device  404 , such as a touchscreen, keyboard, electronic mouse, microphone, or the like. For example, the control unit  402  can receive manually input changes to the tractive effort, braking effort, speed, power output, and the like, from the input device  404 . The control unit  402  may receive a single instance of an actuation of the input device  404  to initiate the establishment of communication links between lead and remote vehicles in the vehicle consist. For example, instead of having one or more operators go onboard lead and remote vehicles of a consist in order to establish communication links for the remote control of the remote vehicles by the lead vehicles, an operator may go onboard the lead vehicle and press a single button or other input device to cause the lead vehicle to communicate linking messages to the remote vehicles in order to establish the communication links. 
     The control unit  402  can present information to the operator using the output device  406 , which can represent a display screen (e.g., touchscreen or other screen), speakers, printer, or the like. For example, the control unit  402  can present the identities and statuses of the remote vehicles  106 , identities of the missing remote vehicles  106  (e.g., those remote vehicles  106  from which the lead vehicle  104  has not received the status), contents of one or more command messages, or the like. 
     The control unit  402  is connected with a propulsion subsystem  408  of the propulsion-generating vehicle  400 . The propulsion subsystem  408  provides tractive effort and/or braking effort of the propulsion-generating vehicle  400 . The propulsion subsystem  408  may include or represent one or more engines, motors, alternators, generators, brakes, batteries, turbines, and the like, that operate to propel the propulsion-generating vehicle  400  under the manual or autonomous control that is implemented by the control unit  402 . For example, the control unit  402  can generate control signals autonomously or based on manual input that is used to direct operations of the propulsion subsystem  408 . 
     The control unit  402  also is connected with a communication unit  410  and a memory  412  of the communication system in the propulsion-generating vehicle  400 . The memory  412  can represent an onboard device that electronically and/or magnetically stores data. For example, the memory  412  may represent a computer hard drive, random access memory, read-only memory, dynamic random access memory, an optical drive, or the like. The communication unit  410  includes or represents hardware and/or software that is used to communicate with other vehicles  400  in the vehicle consist  102 . For example, the communication unit  410  may include a transceiver and associated circuitry (e.g., antennas)  414  for wirelessly communicating (e.g., communicating and/or receiving) linking messages, command messages, linking confirmation messages, reply messages, retry messages, repeat messages, or the like. Optionally, the communication unit  410  includes circuitry for communicating the messages over a wired connection  416 , such as an electric multiple unit (eMU) line of the vehicle consist  102 , catenary or third rail of electrically powered vehicle, or another conductive pathway between or among the propulsion-generating vehicles  104 ,  106 ,  400  in the vehicle consist  102 . The control unit  402  may control the communication unit  410  by activating the communication unit  410 . The communication unit  410  can examine the messages that are received by the vehicle  400 . For example, the communication unit  410  of a remote vehicle  106  can examine received command messages to determine the directive sent by the lead vehicle  104 . The directive can be conveyed to the control unit  402 , which then implements the directive by creating control signals that are communicated to the propulsion subsystem  408  for autonomous control or by presenting the directive to the operator on the output device  406  for manual implementation of the directive. 
     The memory  412  can store vehicle identifiers. In the lead vehicle  104 , the memory  412  can store the vehicle identifiers of the remote vehicles  106  in the same consist as the lead vehicle  104 . In the remote vehicles  106 , the memory  412  can store the vehicle identifier of the remote vehicle  106  in which the memory  412  is located (e.g., to allow the remote vehicle  106  to communicate the vehicle identifier), the vehicle identifier of the lead vehicle  104  (e.g., to allow the remote vehicle  106  to verify that received messages are sent from the lead vehicle  104  in the same consist), and/or other information. 
     The control unit  402  can obtain the vehicle identifiers from another system, such as a vehicle control system  418 , an energy management system  416 , or another system. The vehicle control system  418  shown in  FIG. 3  can include hardware circuits or circuitry that include and/or are connected with one or more processors. The vehicle control system  418  can control or limit movement of the vehicle  400  and/or the vehicle consist that includes the vehicle  400  based on one or more limitations. For example, the vehicle control system  418  can prevent the vehicle and/or vehicle consist from entering into a restricted area, can prevent the vehicle and/or vehicle consist from exiting a designated area, can prevent the vehicle and/or vehicle consist from traveling at a speed that exceeds an upper speed limit, can prevent the vehicle and/or vehicle consist from traveling at a speed that is less than a lower speed limit, or the like. In one embodiment, the vehicle control system  418  includes or represents a positive train control system. The vehicle control system  418  may be programmed or otherwise have access to the vehicle identifiers of the vehicles included in the vehicle consist that includes the vehicle  400 . For example, the vehicle control system  418  may store right access to the vehicle identifiers so that the vehicle control system  418  can determine how to control or limit control of the vehicle  400  and/or the vehicle consist that includes the vehicle  400  in order to prevent the vehicle  400  and/or vehicle consist from violating one or more of the limits. 
     The energy management system  416  can include hardware circuits or circuitry that include and and/or are connected with one or more processors. The energy management system  416  can create a trip plans for trips of the vehicle  400  and/or the vehicle consist that includes the vehicle  400 . As described above, a trip plan may designate operational settings of the vehicle  400  and/or the vehicle consist as a function of time and/or distance along a route for a trip. Traveling according to the operational settings designated by the trip plan can reduce fuel consumed and/or emissions generated by the vehicle  400  and/or the vehicle consist relative to the vehicle  400  and/or vehicle consist traveling according to other operational settings that are not designated by the trip plan. The energy management system  416  may be programmed with or otherwise have access to the vehicle identifiers of the vehicles included in the vehicle consist. The identities of the vehicles in the consists may be known to energy management system  416  so that the energy management system  416  can determine what operational settings to designate for a trip plan in order to achieve a goal of reducing fuel consumed and/or emissions generated by the consists during the trip. 
     One or more of the vehicle control system  418 , the energy management system  416 , or another system may communicate or otherwise provide the vehicle identifiers to the control unit  402  and/or the communication unit  410 . As described above, the communication unit  410  and/or the control unit  402  may communicate wireless linking messages that are addressed to the remote vehicles in the consist using the vehicle identifiers obtained from one or more of the systems. 
       FIG. 4  illustrates several vehicles  302 ,  304  (e.g.,  304 A,  304 B),  306 ,  308 ,  310  located on neighboring routes  312  according to one example. The vehicles  302 ,  304 ,  306 ,  308 ,  310  can represent one or more of the vehicles  104 ,  106 ,  108 ,  400  shown in  FIGS. 1 and 3 . The routes  312  may be relatively close to one another, such as within five, ten, fifteen, twenty, twenty-five meters or another distance apart. For example, the routes  312  may be neighboring tracks in a vehicle yard, such as a rail yard. Alternatively, the routes may be another type of route and/or another location. 
     The vehicles  302 ,  304 ,  306  may be grouped together in the vehicle consist  300 . For example, the vehicle  302  may represent the lead vehicle  104  shown in  FIG. 1 , the vehicles  304 A,  304 B may represent remote vehicles  106  shown in  FIG. 1 , and the vehicle  306  may represent a non-propulsion-generating vehicle  108  shown in  FIG. 1 . Other vehicles  308 ,  310  shown in  FIG. 4  are not included in the vehicle consist  300 . For example, vehicles  308 ,  310  are not grouped with the vehicles  302 ,  304 ,  306  to travel with the vehicles  302 ,  304 ,  306  along a route  312 . Instead, the vehicles  308 ,  310  may be included in another vehicle consist or may not be included in any vehicle consist. 
     The communication unit  410  (shown in  FIG. 3 ) of the lead vehicle  302  may have a wireless communication range  314 . The range  314  indicates how far wireless messages sent from the communication unit  410  of the lead vehicle  302  may be successfully communicated to another vehicle. In the illustrated example, the vehicles  304 ,  306 ,  308  are within the wireless range  314  lead vehicle  302 , while the vehicles  310  are outside of the wireless range  314  the lead vehicle  302 . As a result, wireless messages (such as wireless linking messages) communicated from the lead vehicle  302  may be received by the vehicles  304 ,  306 ,  308 , but not received by the vehicles  310 . 
     Communicating the wireless linking messages from the lead vehicle  302  with the vehicle identifiers of the remote vehicles  304 A,  304 B can prevent establishment of communication links with the vehicles  308  that are within the wireless range  314  of the lead vehicle  302 , but that are not included in the vehicle consist  300  of the lead vehicle  302 . For example, one or more of the vehicles  308  may receive a wireless linking message the lead vehicle  302 . These vehicles  308  can examine the vehicle identifier or vehicle identifiers included in the wireless linking message to determine if the vehicle identifier or identifiers in the wireless linking message matches the vehicle identifier associated with the vehicle  308 . Because the vehicle identifiers in the wireless linking messages do not match or otherwise correspond with the vehicles  308 , the vehicles  308  may determine that the wireless linking messages are not addressed to the vehicles  308 . As a result, the vehicles  308  do not establish a communication link with the lead vehicle and/or do not respond to the wireless linking message with a linking confirmation message sent back to lead vehicle  302 . Because the vehicle identifiers included in the linking message do match or otherwise correspond with the remote vehicles  304 A,  304 B, these vehicles  304 A,  304 B do establish communication link with the lead vehicle  302  and/or establish the communication links by responding with a linking confirmation message. 
     In one embodiment, a method (e.g., for communicatively linking vehicles in a vehicle consist) includes determining a vehicle identifier for a first remote vehicle included in a vehicle consist formed from a lead vehicle and at least the first remote vehicle, communicating a wireless linking message addressed to the vehicle identifier from the lead vehicle to the first remote vehicle, and establishing a communication link between the lead vehicle and the first remote vehicle responsive to receipt of the wireless linking message at the first remote vehicle. The communication link can be established such that movement of the first remote vehicle is remotely controlled from the lead vehicle via the communication link. The communication link can be established without an operator entering the first remote vehicle. 
     In one aspect, establishing the communication link can include receiving a wireless linking confirmation message from the first remote vehicle at the lead vehicle responsive to the wireless linking message being received at the first remote vehicle. 
     In one aspect, determining the vehicle identifier can include receiving a list of one or more unique identifying codes associated with at least the first remote vehicle from a vehicle control system that restricts movement of the vehicle consist based at least in part on a location of the vehicle consist. 
     In one aspect, the vehicle control system can include a positive train control system. 
     In one aspect, determining the vehicle identifier can include receiving a list of one or more unique identifying codes associated with at least the first remote vehicle from an energy management system that creates a trip plan to control movement of the vehicle consist. The trip plan can designate operational settings of the vehicle consist as a function of one or more of time or distance along a route. 
     In one aspect, the vehicle consist includes the lead vehicle, the first remote vehicle, and at least a second remote vehicle. Determining the vehicle identifier can include determining a first unique vehicle identifier for the first remote vehicle and at least a second unique vehicle identifier for at least the second remote vehicle. Communicating the wireless linking message can include communicating a first wireless linking message to the first remote vehicle and communicating at least a second wireless linking message to at least the second remote vehicle. Establishing the communication link can include establishing a first communication link between the lead vehicle and the first remote vehicle and at least a second communication link between the lead vehicle and at least the second remote vehicle. 
     In one aspect, the method also can include detecting a single instance of an operator actuating an input device onboard the lead vehicle and communicating the first wireless linking message and the at least the second wireless linking message responsive to detecting the single instance of the operator actuating the input device. 
     In one aspect, communicating the wireless linking message can include broadcasting the wireless linking message such that the first remote vehicle receives the wireless linking message and at least one other remote vehicle that is located within a wireless communication range of the lead vehicle but that is not included in the vehicle consist receives the wireless linking message. Establishing the communication link between the lead vehicle and the first remote vehicle can include preventing the at least one other remote vehicle from establishing a communication link with the lead vehicle based at least in part on the vehicle identifier. 
     In another embodiment, a system (e.g., a communication system) includes a control unit and a communication unit. The control unit can be configured to determine a vehicle identifier for a first remote vehicle included in a vehicle consist formed from a lead vehicle and at least the first remote vehicle. The communication unit can be configured to communicate a wireless linking message addressed to the vehicle identifier from the lead vehicle to the first remote vehicle. The communication unit also can be configured to establish a communication link between the lead vehicle and the first remote vehicle responsive to receipt of the wireless linking message at the first remote vehicle. The control unit can be configured to remotely control movement of the first remote vehicle from the lead vehicle via the communication link. The communication link can be established without an operator entering the first remote vehicle. 
     In one aspect, the communication unit can be configured to receive a wireless linking confirmation message from the first remote vehicle at the lead vehicle responsive to the wireless linking message being received at the first remote vehicle. 
     In one aspect, the control unit can be configured to determine the vehicle identifier by receiving a list of one or more unique identifying codes associated with at least the first remote vehicle from a vehicle control system that restricts movement of the vehicle consist based at least in part on a location of the vehicle consist. 
     In one aspect, the vehicle control system can include a positive train control system. 
     In one aspect, the control unit can be configured to determine the vehicle identifier by receiving a list of one or more unique identifying codes associated with at least the first remote vehicle from an energy management system that creates a trip plan to control movement of the vehicle consist. The trip plan can designate operational settings of the vehicle consist as a function of one or more of time or distance along a route. 
     In one aspect, the vehicle consist can include the lead vehicle, the first remote vehicle, and at least a second remote vehicle. The control unit can be configured to determine the vehicle identifier by determining a first unique vehicle identifier for the first remote vehicle and at least a second unique vehicle identifier for at least the second remote vehicle. The communication unit can be configured to communicate the wireless linking message by communicating a first wireless linking message to the first remote vehicle and communicating at least a second wireless linking message to at least the second remote vehicle. The communication unit also can be configured to establish the communication link by establishing a first communication link between the lead vehicle and the first remote vehicle and at least a second communication link between the lead vehicle and at least the second remote vehicle. 
     In one aspect, the control unit can be configured to detect a single instance of an operator actuating an input device onboard the lead vehicle and the communication unit can be configured to communicate the first wireless linking message and the at least the second wireless linking message responsive to the control unit detecting the single instance of the operator actuating the input device. 
     In one aspect, the communication unit can be configured to communicate the wireless linking message by broadcasting the wireless linking message such that the first remote vehicle receives the wireless linking message and at least one other remote vehicle that is located within a wireless communication range of the communication unit but that is not included in the vehicle consist receives the wireless linking message. The communication unit can be configured to prevent the at least one other remote vehicle from establishing a communication link with the lead vehicle based at least in part on the vehicle identifier. 
     In another embodiment, a method (e.g., for communicatively linking vehicles in a vehicle consist) includes receiving unique vehicle identifiers of remote vehicles included in a vehicle consist with a lead vehicle, communicating linking messages with the unique vehicle identifiers to the remote vehicles, and responsive to the unique vehicle identifiers in the linking messages matching the remote vehicles in the vehicle consist, establishing one or more communication links between the lead vehicle and the remote vehicles to permit the lead vehicle to remotely control movement of the remote vehicles included in the vehicle consist. The one or more communication links are established without an operator being onboard the remote vehicles to communicate responsive messages from the remote vehicles to the lead vehicle. 
     In one aspect, establishing the one or more communication links can include receiving one or more linking confirmation messages from the remote vehicles at the lead vehicle responsive to the linking messages being received at the remote vehicles without the operator being onboard the remote vehicles. 
     In one aspect, determining the vehicle identifiers can include receiving a list of one or more unique identifying codes associated with the remote vehicles from one or more of a vehicle control system that restricts movement of the vehicle consist based at least in part on a location of the vehicle consist and/or an energy management system that creates a trip plan to control movement of the vehicle consist. The trip plan can designate operational settings of the vehicle consist as a function of one or more of time or distance along a route. 
     In one aspect, the method also can include detecting a single instance of an operator actuating an input device onboard the lead vehicle and communicating the linking messages occurs responsive to detecting the single instance of the operator actuating the input device. 
     In another embodiment, a method (e.g., for communicatively linking vehicles in a vehicle consist) includes determining a first unique vehicle identifier for a first remote vehicle and a second unique vehicle identifier for a second remote vehicle included in a vehicle consist formed from a lead vehicle, the first remote vehicle, and the second remote vehicle, detecting a single instance of an operator actuating an input device onboard the lead vehicle, communicating from the lead vehicle a first wireless linking message addressed to the first unique vehicle identifier to the first remote vehicle and communicating a second wireless linking message addressed to the second unique vehicle identifier to the second remote vehicle responsive to detecting the single instance of the operator actuating the input device, establishing a first communication link between the lead vehicle and the first remote vehicle responsive to receipt of the first wireless linking message at the first remote vehicle and a second communication link between the lead vehicle and the second remote vehicle responsive to receipt of the second wireless linking message at the second remote vehicle (where the communication link is established without an operator entering the first remote vehicle or the second remote vehicle), and remotely controlling movement of the first remote vehicle and the second remote vehicle from the lead vehicle via the first communication link and the second communication link, respectively. Communicating the wireless linking message can include broadcasting the first wireless linking message and the second wireless linking message such that the first remote vehicle receives the first wireless linking message and the second remote vehicle receives the second wireless linking message and at least one other remote vehicle that is located within a wireless communication range of the lead vehicle but that is not included in the vehicle consist receives at least one of the first wireless linking message or the second wireless linking message. Establishing the first communication link between the lead vehicle and the first remote vehicle and the second communication link between the lead vehicle and the second remote vehicle can include preventing the at least one other remote vehicle from establishing a communication link with the lead vehicle based at least in part on the first unique vehicle identifier or the second unique vehicle identifier. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the inventive subject matter without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the inventive subject matter, they are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to one of ordinary skill in the art upon reviewing the above description. The scope of the inventive subject matter should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. 
     This written description uses examples to disclose several embodiments of the inventive subject matter and also to enable one of ordinary skill in the art to practice the embodiments of inventive subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the inventive subject matter is defined by the claims, and may include other examples that occur to one of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 
     The foregoing description of certain embodiments of the present inventive subject matter will be better understood when read in conjunction with the appended drawings. To the extent that the figures illustrate diagrams of the functional blocks of various embodiments, the functional blocks are not necessarily indicative of the division between hardware circuitry. Thus, for example, one or more of the functional blocks (for example, processors or memories) may be implemented in a single piece of hardware (for example, a general purpose signal processor, microcontroller, random access memory, hard disk, and the like). Similarly, the programs may be stand-alone programs, may be incorporated as subroutines in an operating system, may be functions in an installed software package, and the like. The various embodiments are not limited to the arrangements and instrumentality shown in the drawings. 
     As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present inventive subject matter are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.