Patent Publication Number: US-2021171076-A1

Title: Transmission system and transmission method

Description:
FIELD 
     The present invention relates to a transmission system to be installed in a train and to a transmission method. 
     BACKGROUND 
     Conventionally, an onboard network constructed in a train assigns a priority to information to be transmitted and prioritizes transmission of information assigned with a high priority. Patent Literature  1  discloses a technique in an information transmission system to set in advance a higher priority to control information than the priority assigned to media information to prioritize transmission of the control information over the media information so as to ensure real-time transmission of the control information. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Application Laid-open No. 2005-333724 
     SUMMARY 
     Technical Problem 
     However, the information transmission system disclosed in Patent Literature  1  does not take into account the operating state of a device that is a source of the information. In a case where an ATO (Automatic Train Operation: driving assistant) is installed in a train, even when the driving assist function is set disabled and a driver is manually driving the train, the ATO still transmits a control command for checking for connection thereof with other devices. The control command for checking for connection is not intended to control operation of a device installed in a vehicle, but is still transmitted as a control command from the ATO with a priority as high as a control command issued when the driving assist function is set enabled. This leads to a problem that there is a possibility that transmission of the control command for checking for connection from the ATO may cause a delay in transmitting a control command from another device which needs to be transmitted in a real-time manner. 
     The present invention has been achieved to solve the above problems, and an object of the present invention is to provide a transmission system capable of changing a priority assigned to a control command in accordance with an operating state of a device that is a source of the control command. 
     Solution to Problem 
     To solve the above problems and achieve the object, a transmission system according to the present invention includes: a transmitter to receive a control command from two or more controllers that control operation of an in-vehicle machinery installed in a train, and to control an output of the control command on a basis of a priority assigned to the control command; and a system-controller to determine an operating state of a controller that is a source of the control command, the system-controller being capable of changing a priority assigned to a control command transmitted from a controller whose operating state has been determined, on a basis of a determination result. 
     Advantageous Effects of Invention 
     According to the present invention, there is an effect where it is possible to change a priority assigned to a control command in accordance with an operating state of a device that is a source of the control command. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating a configuration example of a transmission system. 
         FIG. 2  is a block diagram illustrating a configuration example of a hub and a system-controller. 
         FIG. 3  is a diagram illustrating an example of a format of a control command. 
         FIG. 4  is a flowchart illustrating operation to transmit a control command in the transmission system. 
         FIG. 5  is a diagram illustrating an example in a case where a processing circuitry included in the system-controller is configured by a processor and a memory. 
         FIG. 6  is a diagram illustrating an example in a case where the processing circuitry included in the system-controller is configured by dedicated hardware. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A transmission system and a transmission method according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The present invention is not limited to the embodiment. 
     Embodiment. 
       FIG. 1  is a diagram illustrating a configuration example of a transmission system  10  according to an embodiment of the present invention. The transmission system  10  is installed in a train (not illustrated). In the transmission system  10 , a controller controls operation of an in-vehicle machinery. The transmission system  10  includes an ATO  1 , a master controller  2 , hubs  3  and  5 , a system-controller  4 , a recording server  6 , and a brake  7 . 
     The brake  7  is an example of the in-vehicle machinery installed in the train. The in-vehicle machinery is not limited to the brake  7  and may be a device whose operation is controlled in accordance with an instruction from at least one of the ATO  1  and the master controller  2 . It is allowable that in the transmission system  10 , there are a plurality of in-vehicle machineries. The ATO  1  and the master controller  2  are controllers to control operation of the in-vehicle machinery that is the brake  7 . The recording server  6  records therein information on a control command to be transmitted in the transmission system  10 . 
     The hubs  3  and  5  are transmitters having a function of transferring a received control command. The hubs  3  and  5  have nearly the same function. However, the hubs  3  and  5  operate in a different manner depending on differences in connection configurations, that is, differences in devices to be respectively connected thereto. When the hub  3  receives a control command from the ATO  1  and the master controller  2 , the hub  3  controls the output of the control commands on the basis of a priority assigned to each of the control commands, that is, controls the order of outputting the control commands. While in an example of  FIG. 1 , there are two controllers connected to the hub  3 , this is merely an example. It is allowable that three or more controllers are connected to the hub  3 . The hub  5  outputs a control command received from the hub  3  to the recording server  6  and the brake  7 . In the example of  FIG. 1 , there is only one in-vehicle machinery, which is the brake  7 , connected to the hub  5 , however, this is merely an example. It is allowable that two or more in-vehicle machineries are connected to the hub  5 . It is allowable that the hubs  3  and  5  are installed separately in different vehicles or are installed in the same vehicle. In a case where the hubs  3  and  5  are installed separately in different vehicles, as the number of connected vehicles in the train is increased, the number of hubs is increased in the transmission system  10 . In the example in  FIG. 1 , the in-vehicle machinery that is the brake  7  is connected only to the hub  5 . However, an in-vehicle machinery may be connected to the hub  3 . In a case where the transmission system  10  includes three or more hubs, in-vehicle machineries may be connected respectively to the hubs. 
     The system-controller  4  determines an operating state of a controller that is a source of the control command. On the basis of the operating state of the controller that is a source of the control command, the system-controller  4  sets a priority to a control command transmitted from the controller, whose operating state has been determined, for the hub  3 . That is, the system-controller  4  can change the priority set to a control command transmitted from a controller, whose operating state has been determined, for the hub  3 . In the present embodiment, the ATO  1  is defined as a controller for which the system-controller  4  is capable of changing the priority set to a control command. For example, the system-controller  4  is installed in a driver&#39;s cab (not illustrated) of the train. 
     In the Ethernet® network, the transmission system  10  transmits Ethernet packets. In the transmission system  10 , the ATO  1  and the master controller  2  transmit an Ethernet packet including control information as a control command, and the hubs  3  and  5  transfer the control command that is the Ethernet packet. 
     The configurations of the hub  3  and the system-controller  4  are described below.  FIG. 2  is a block diagram illustrating a configuration example of the hub  3  and the system-controller  4  according to the present embodiment. As illustrated in  FIG. 2 , the hub  3  includes a switch  31  and a switch control unit  32 . On the basis of the control by the switch control unit  32 , the switch  31  outputs a control command received from the ATO  1  and the master controller  2  on the basis of a set priority. For example, the switch  31  is a layer  2  switch. On the basis of the control by the system-controller  4 , the switch control unit  32  sets a priority to a control command for the switch  31 . 
     As illustrated in  FIG. 2 , the system-controller  4  includes an obtaining unit  41  and a control unit  42 . The obtaining unit  41  obtains a control command output from the switch  31  in the hub  3 , and outputs the control command to the control unit  42 . 
     The control unit  42  monitors the control command obtained through the obtaining unit  41  and determines an operating state of the ATO  1 . Specifically, the control unit  42  refers to a field indicating the operating state in a data section of the control command transmitted from the ATO  1 , that is, an Ethernet packet. The control unit  42  determines an operating state of the ATO  1  on the basis of an information bit in the field indicating the operating state.  FIG. 3  is a diagram illustrating an example of the format of a control command according to the present embodiment. In general, in a control command transmitted from the ATO  1 , namely in an Ethernet packet, a header section  51  and a data section  52  are included. In the Ethernet packet, the header section  51  includes a tag field in which a priority and the like can be set to the packet. However, during operation of the transmission system  10 , the tag information set for each type of the Ethernet packet remains unchanged. In the transmission system  10 , a high priority is set in the tag in the header section  51  of a control command transmitted from the ATO  1 , and also a high priority is set in the tag in the header section  51  of a control command transmitted from the master controller  2 . In contrast, in the field of an operating state  53  in the data section  52 , an information bit in the operating state  53  dynamically changes depending on the operating state of the ATO  1 . 
     Operating states of the ATO  1  include a state in which the ATO  1  assists a driver who is driving the train, and a state in which the driving assist function is set disabled because the driver is manually driving the train. The control unit  42  determines which of the operating states the ATO  1  is in on the basis of the information bit described above. When the ATO  1  is in a state of assisting the driver driving the train, the control unit  42  determines that the operating state of the ATO  1  is an assisting state. The control unit  42  assigns a high priority to a control command transmitted from the ATO  1  when the ATO  1  is determined to be in the assisting state. As described above, a control command transmitted from the master controller  2  is also assigned with a high priority. When the ATO  1  is brought into a state in which the driving assist function is set disabled because the driver is manually driving the train, the control unit  42  determines that the operating state of the ATO  1  is a non-assisting state. The control unit  42  assigns a low priority to a control command transmitted from the ATO  1  when the ATO  1  is determined to be in the non-assisting state, relative to the high priority described above. A low-priority control command when the ATO  1  is determined to be in the non-assisting state does not include control information on controlling the in-vehicle machinery, that is, does not include valid control information. A low-priority control command transmitted from the ATO  1  when the ATO  1  is determined to be in the non-assisting state is referred to as “invalid control command”. The invalid control command is not intended to control operation of the in-vehicle machinery, but is intended to check for connection, that is, intended to be recorded in the recording server  6 . The invalid control command does not need to be transmitted in a real-time manner. Even though the invalid control command is assigned with a low priority, this does not cause any problem. On the basis of the determination result, the control unit  42  instructs the switch control unit  32  in the hub  3  whether to transmit a control command having been transmitted from the ATO  1  with a high priority or a low priority. As described above, in a case where the operating state of the ATO  1  is determined to be the non-assisting state, although tag information in the header section  51  of an invalid control command transmitted from the ATO  1  indicates a high priority, the control unit  42  assigns a low priority to the invalid control command without changing the tag information. 
     Next, operation of the hub  3  and the system-controller  4  is described.  FIG. 4  is a flowchart illustrating operation to transmit a control command in the transmission system  10  according to the present embodiment. In the transmission system  10 , the switch  31  in the hub  3  determines whether a received control command has been transmitted from the ATO  1  (Step S 1 ). For example, the switch  31  refers to a source address of the received control command and determines whether the control command has been transmitted from the ATO  1 . The source address is included in the header section  51  of the format of the control command described above. When the control command has been transmitted from the ATO  1  (YES at Step S 1 ), the switch  31  outputs the control command received from the ATO  1  to the hub  5  located at the subsequent stage, as well as to the system-controller  4  (Step S 2 ). When the control command has been transmitted from the master controller  2  (NO at Step S 1 ), the switch  31  outputs the control command received from the master controller  2  to the hub  5  (Step S 3 ). It is allowable that the hub  3  does not determine a source of each control command, but outputs all control commands to the system-controller  4 . In this case, the system-controller  4  determines whether a received control command has been transmitted from the ATO  1 . 
     When the control unit  42  in the system-controller  4  obtains a control command through the obtaining unit  41 , the control unit  42  determines an operating state of the ATO  1  (Step S 4 ). Specifically, the control unit  42  refers to an information bit of the operating state  53  in the data section  52  of the control command, that is, the Ethernet packet. When the control unit  42  determines that the operating state of the ATO  1  is the assisting state (YES at Step S 5 ), the control unit  42  assigns a high priority to the control command transmitted from the ATO  1 . The control unit  42  instructs the switch control unit  32  to set a high priority to the control command transmitted from the ATO  1 , and to output this control command (Step S 6 ). When the control unit  42  determines that the operating state of the ATO  1  is the non-assisting state (NO at Step S 5 ), the control unit  42  assigns a low priority to the control command transmitted from the ATO  1 . The control unit  42  instructs the switch control unit  32  to set a low priority to the control command transmitted from the ATO  1 , and to output this control command (Step S 7 ). 
     On the basis of the instruction from the control unit  42  at Step S 6  or Step S 7 , the switch control unit  32  in the hub  3  sets a priority to the control command transmitted from the ATO  1  for the switch  31  (Step S 8 ). In accordance with the setting by the switch control unit  32 , the switch  31  outputs the control command transmitted from the ATO  1  (Step S 9 ). 
     At Step S 9  subsequent to Steps S 7  and S 8 , when the switch  31  assigns a low priority to a control command transmitted from the ATO  1  in the non-assisting state, that is, an invalid control command, and outputs this control command: when the switch  31  receives a control command from the master controller  2  while outputting the control command of the ATO  1 , the switch  31  stops outputting the control command of the ATO  1  so as to output the control command of the master controller  2  prior to the control command of the ATO  1 . A control command transmitted from a controller other than the ATO  1 , that is, from the master controller  2  in the example in  FIG. 1  is assigned with a high priority as described above. As illustrated in  FIG. 1 , in the hub  3 , when the switch  31  receives a control command B 1  from the master controller  2  while outputting a control command A 1  of the ATO  1  in the non-assisting state, the switch  31  stops outputting the control command A 1  of the ATO  1  so as to output the control command B 1  of the master controller  2 . After having output the control command B 1  of the master controller  2 , the switch  31  outputs the remaining portion of the control command A 1  of the ATO  1  which has not yet been output. While outputting the control command A 1  and the control command B 1 , the switch  31  receives a control command A 2  from the ATO  1  in the non-assisting state and receives a control command B 2  from the master controller  2 . Although the switch  31  receives the control command B 2  of the master controller  2  while outputting the remaining portion of the control command A 1  of the ATO  1  which has not yet been output, for example, when the number of parts into which a control command is divided is set to “2”, or when a portion of the control command A 1  of the ATO  1  which has not yet been output is equal to or less than the minimum limit of output at the point in time when the switch  31  receives the control command B 2  of the master controller  2 , then the switch  31  continues to output the remaining portion of the control command A 1  of the ATO  1  which has not yet been output. Next, the switch  31  outputs the control command B 2  of the master controller  2 , and thereafter outputs the control command A 2  of the ATO  1 . In the same manner as described above, when the switch  31  receives a control command B 3  from the master controller  2  while outputting the control command A 2  of the ATO  1 , the switch  31  also stops outputting the control command A 2  of the ATO  1  so as to output the control command B 3  of the master controller  2 . After having output the control command B 3  of the master controller  2 , the switch  31  outputs the remaining portion of the control command A 2  of the ATO  1  which has not yet been output. The switch  31  receives the control command A 3  from the ATO  1  in the non-assisting state, and outputs the control command A 3  of the ATO  1 . When the switch  31  assigns a high priority to a control command transmitted from the ATO  1  in the assisting state and outputs the control command at Step S 9  subsequent to Steps S 6  and S 8 , the switch  31  outputs the control command in the order of receiving this control command. In the example in  FIG. 1 , since the switch  31  receives the control command A 1 , the control command B 1 , the control command A 2 , the control command B 2 , the control command A 3 , and the control command B 3  in the order described, the switch  31  outputs the control command A 1 , the control command B 1 , the control command A 2 , the control command B 2 , the control command A 3 , and the control command B 3  in the same order as the order of receiving these control commands. 
     When the hub  5  receives each divided part of a control command from the hub  3 , the hub  5  restores the divided parts of the control command into a single control command and outputs the restored single control command. At this time, the hub  5  prioritizes the output of an undivided control command over the divided control command. As illustrated in  FIG. 1 , when the hub  5  receives a portion of the control command A 1 , the control command B 1 , the remaining portion of the control command A 1 , the control command B 2 , a portion of the control command A 2 , the control command B 3 , the remaining portion of the control command A 2 , and the control command A 3  in the order described: then the hub  5  outputs the control command B 1 , the control command A 1 , the control command B 2 , the control command B 3 , the control command A 2 , and the control command A 3  to the recording server  6  and the brake  7  in the order described. 
     A case is assumed in which when the operating state of the ATO  1  is determined to be the non-assisting state, the priority assigned to an invalid control command is not changed from a high priority to a low priority. In this case, when the hub  3  receives the control command A 1 , the control command B 1 , the control command A 2 , the control command B 2 , the control command A 3 , and the control command B 3  in the order described, the hub  3  outputs the control command A 1 , the control command B 1 , the control command A 2 , the control command B 2 , the control command A 3 , and the control command B 3  to the hub  5  in the same order as the order of receiving these control commands. In the same manner as the hub  3 , the hub  5  outputs the control command A 1 , the control command B 1 , the control command A 2 , the control command B 2 , the control command A 3 , and the control command B 3  to the recording server  6  and the brake  7  in the order described. The order of outputting the control commands B 1  to B 3  of the master controller  2  is compared between a case where the priority assigned to an invalid control command is changed and a case where the priority assigned to an invalid control command is not changed. The comparison shows that in the case where the priority assigned to an invalid control command is changed, the hub  5  can advance the outputting order of the control command B 1  by one, advance the outputting order of the control command B 2  by one, and advance the outputting order of the control command B 3  by two. That is, in the transmission system  10 , when the operating state of the ATO  1  is determined to be the non-assisting state, the priority assigned to an invalid control command is changed to a low priority, so that the transmission system  10  can prioritize transmission of a control command having been transmitted from a controller other than the ATO  1 , and can improve real-time transmission. 
     When the operating state of the ATO  1  is determined to be the non-assisting state, the system-controller  4  does not execute an invalid control command-based control on the brake  7 . Accordingly, even though the brake  7  does not receive an invalid control command when the operating state of the ATO  1  is determined to be the non-assisting state, this does not cause any problem. For this reason, it is allowable that the system-controller  4  instructs the hubs  3  and  5  to stop outputting an invalid control command to the in-vehicle machinery that is the brake  7 . In the system-controller  4 , when the control unit  42  determines that the operating state of the ATO  1  is the non-assisting state, the control unit  42  instructs the switch control unit  32  to set a low priority to a control command transmitted from the ATO  1  and output this control command, and to stop outputting an invalid control command to the in-vehicle machinery. The switch control unit  32  instructs the switch  31  to set a low priority to a control command transmitted from the ATO  1  and output this control command, and also instructs the switch  31  to generate an output control packet that instructs the hub  5  to stop outputting an invalid control command to the in-vehicle machinery, and to output this output control packet to the hub  5 . The switch  31  in the hub  3  outputs the output control packet to the hub  5  through the same path as used for outputting a control command. When the hub  5  receives the output control packet from the hub  3 , the hub  5  does not output an invalid control command that is received after the hub  5  has received the output control packet, that is, does not output a control command transmitted from the source, that is the ATO  1 , to the brake  7 . On the basis of the instruction to stop outputting the invalid control command, when the destination of the invalid control command is the recording server  6  or another hub, then the hubs  3  and  5  output the invalid control command. When the destination of the invalid control command is the in-vehicle machinery, the hubs  3  and  5  do not output the invalid control command. Due to this operation, the transmission system  10  can reduce an unnecessary processing load to be imposed by receiving the invalid control command at the brake  7 . 
     Next, a hardware configuration of the system-controller  4  is described. In the system-controller  4 , the obtaining unit  41  is implemented by a communication interface circuit. The control unit  42  is implemented by a processing circuitry. The processing circuitry may be a memory and a processor that executes programs stored in the memory, or may be a dedicated hardware. 
       FIG. 5  is a diagram illustrating an example in a case where the processing circuitry included in the system-controller  4  according to the present embodiment is configured by a processor and a memory. In a case where the processing circuitry is configured by a processor  91  and a memory  92 , the functions of the processing circuitry of the system-controller  4  are implemented in software, firmware, or a combination of the software and the firmware. The software or firmware is written as a program and stored in the memory  92 . In the processing circuitry, the processor  91  reads and executes the program stored in the memory  92  to thereby implement each of the functions. That is, the processing circuitry includes the memory  92  that stores therein programs that eventually execute operation of the system-controller  4 . These programs are also regarded as causing a computer to execute the procedure and the method of the system-controller  4 . 
     The processor  91  may be a device such as a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, and a DSP (Digital Signal Processor). For example, a nonvolatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), and an EEPROM® (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a MiniDisk, or a DVD (Digital Versatile Disk) correspond to the memory  92 . 
       FIG. 6  is a diagram illustrating an example in a case where the processing circuitry included in the system-controller  4  according to the present embodiment is configured by dedicated hardware. When the processing circuitry is configured by dedicated hardware, then for example, a single circuit, a combined circuit, a programmed processor, a parallel-programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof correspond to a processing circuitry  93  illustrated in  FIG. 6 . The functions of the system-controller  4  may be implemented by each individual processing circuitry  93  or may be collectively implemented by a single processing circuitry  93 . 
     As for each of the functions of the system-controller  4 , it is possible to configure that some parts of the functions are implemented by dedicated hardware and other parts thereof are implemented by software or firmware. In this manner, the processing circuitry can implement each function described above by dedicated hardware, software, firmware, or a combination of these elements. 
     A hardware configuration of the hub  3  is now described. In the hub  3 , the switch  31  is a layer  2  switch as described above. The switch control unit  32  is implemented by the processing circuitry. The processing circuitry of the hub  3  is configured identically to the processing circuitry of the system-controller  4  as illustrated in  FIG. 5  or  FIG. 6 . 
     As explained above, in the transmission system  10  according to the present embodiment, the system-controller  4  determines an operating state of the ATO  1  on the basis of the operating state  53  included in the data section  52  of a control command transmitted from the ATO  1 : and when the operating state of the ATO  1  is determined to be the non-assisting state in which a driver is manually driving the train, the system-controller  4  sets a low priority to the control command transmitted from the ATO  1  for the hub  3 . Due to this operation, when the operating state of the ATO  1  is determined to be the non-assisting state, the hub  5  can transmit the control command received from the ATO  1  with a low priority and can transmit a control command received from the master controller  2  with a high priority. As described above, in the transmission system  10 , during operation of the train, the system-controller  4  can dynamically change the priority set to a control signal transmitted from the ATO  1  on the basis of the operating state of the ATO  1 . 
     The configurations described in the above embodiment are only examples of the content of the present invention. The configurations can be combined with other well-known techniques, and a part of each configuration can be omitted or modified without departing from the scope of the present invention. 
     REFERENCE SIGNS LIST 
       1  ATO,  2  master controller,  3 ,  5  hub,  4  system-controller,  6  recording server,  7  brake,  10  transmission system,  31  switch,  32  switch control unit, obtaining unit,  42  control unit.