Communication network system

Abstract

To make it possible to suppress a decrease in communication quality even when the number of types of dynamic messages to be transmitted and received between a plurality of electronic control devices increases.SOLUTION: A system 10 includes a plurality of ECUs 20 configured to be able to transmit and receive static messages and dynamic messages via a communication bus 11. Each of the plurality of ECUs 20 sets an upper limit of the number of dynamic messages to be transmitted to the communication bus 11 per unit time to the number of dynamic messages that can be transmitted at its own allocation amount of a second bandwidth. Each of the plurality of ECUs 20 adjusts the transmission of dynamic messages to the communication bus 11 so that the number of dynamic messages transmitted to the communication bus 11 per unit time does not exceed the upper limit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a communication network system including a plurality of electronic control devices. [Background technology]

[0002] The system disclosed in Patent Document 1 includes multiple subscriber stations and communication connections. Each of the multiple subscriber stations can transmit and receive dynamic messages in addition to transmitting and receiving static messages via the communication connections. This allows the system to perform communications that were not anticipated at the system design stage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2018-522487 Summary of the Invention [Problem to be solved by the invention]

[0004] When a software update of a subscriber station or new software is installed in the subscriber station, the number of dynamic messages that the subscriber station transmits to the communication connection per unit time may increase. In such a system, the communication load of the system increases as the number of dynamic messages that multiple subscriber stations transmit to the communication connection per unit time increases. If the communication load of the system becomes excessive, the communication quality of the system may deteriorate. [Means for solving the problem]

[0005] A communication network system for solving the above problems includes a plurality of electronic control devices configured to be able to send and receive static messages and dynamic messages via a communication bus. In the communication network system, the sum of the data lengths of the static messages sent to the communication bus per unit time does not exceed a first bandwidth of the communication bus, and a second bandwidth of the communication bus, excluding the first bandwidth, is allocated to the plurality of electronic control devices as a bandwidth for communicating the dynamic messages. Each of the plurality of electronic control devices sets an upper limit on the number of dynamic messages sent to the communication bus per unit time to the number of dynamic messages that can be sent within its own allocation of the second bandwidth, and adjusts the transmission of the dynamic messages to the communication bus so that the number of dynamic messages sent to the communication bus per unit time does not exceed the upper limit. [Effects of the Invention]

[0006] To suppress a decrease in communication quality even when the number of types of dynamic messages to be transmitted and received between a plurality of electronic control devices increases. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing a communication network system according to the first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the data structure of a static message. [Figure 3] FIG. 3 is a schematic diagram showing the data structure of a dynamic message. [Figure 4] FIG. 4 is a schematic diagram showing the allocation of bandwidths of the communication buses that make up the communication network system of FIG. [Figure 5] FIG. 5 is a flowchart showing a series of processes executed by the electronic control unit when transmitting a message to the communication bus in the communication network system of the first embodiment. [Figure 6]FIG. 6 is a sequence diagram showing the flow of processing when setting an upper limit on the number of dynamic messages to be transmitted to a communication bus per unit time in the communication network system of the first embodiment. [Figure 7] FIG. 7 is a flowchart showing a series of processes executed by the electronic control unit to delete a dynamic message for which a predetermined deletion condition is met in the communication network system of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) A first embodiment of a communication network system will be described below with reference to FIGS. <Communication network system configuration> FIG. 1 shows a communication network system 10 mounted on a vehicle. The communication network system 10 includes a plurality of electronic control units 20. Each of the plurality of electronic control units 20 is configured to be able to send and receive messages via a communication bus 11. Hereinafter, the communication network system 10 will be simply referred to as "system 10." The electronic control unit 20 will be referred to as "ECU 20." "ECU" is an abbreviation for "Electronic Control Unit." An example of a communication bus 11 is a CAN bus. "CAN" is an abbreviation for "Control Area Network."

[0009] The multiple ECUs 20 include an ECU that controls an on-board actuator such as a brake device, an ADAS-ECU, etc. The ECU 20 includes a processing circuit 21 and a communication device 25. The ECU 20 can transmit messages to the communication bus 11 via the communication device 25. The ECU 20 can receive messages from the communication bus 11 via the communication device 25.

[0010] Each of the multiple processing circuits 21 has a CPU 22 and a memory 23. The memory 23 stores various control programs executed by the CPU 22. When the CPU 22 executes the control programs in the memory 23, the processing circuit 21 can provide services corresponding to the control programs.

[0011] <Message> 2 and 3, a message transmitted from the ECU 20 to the communication bus 11 will be described.

[0012] The messages include static messages MG1 and dynamic messages MG2. The static messages MG1 are messages that were assumed to be transmitted from the ECU 20 to the communication bus 11 during the design phase of the system 10. The dynamic messages MG2 are messages that were not assumed to be transmitted from the ECU 20 to the communication bus 11 during the design phase of the system 10. For example, when the control program in the memory 23 is updated, the content of services that the system 10 can provide may change. When the content of the services changes, the types of messages that are transmitted from the ECU 20 to the communication bus 11 may increase. Furthermore, for example, when a new control program is added to the memory 23, the types of services that the system 10 can provide may increase. When the types of services increase, the types of messages that are transmitted from the ECU 20 to the communication bus 11 may increase. In this way, messages that increase due to changes in the content of services or an increase in the number of services correspond to dynamic messages.

[0013] FIG. 2 shows the data structure of the static message MG1. The data length of the static message MG1 is fixed at a specified data length. The static message MG1 includes a header area HD1 and a data area DT1. The header area HD1 includes information indicating the CAN-ID. The CAN-ID is an ID for identifying the message content and the destination ECU. The data area DT1 includes at least one piece of data to be transmitted to another ECU 20 by transmitting the static message MG1.

[0014] 3 shows the data structure of the dynamic message MG2. The data length of the dynamic message MG2 is equal to that of the static message MG1. The dynamic message MG2 includes a header field HD2 and a data field DT2. The header field HD2 includes information indicating the CAN-ID.

[0015] The data area DT2 includes at least one piece of data to be transmitted to another ECU 20 by transmitting the dynamic message MG2. The data area DT2 includes a data ID. The data ID is an ID for identifying, for example, the type of the dynamic message or the ECU to which the dynamic message is to be transmitted.

[0016] <Communication using a communication bus> 4 shows the bandwidth RA of the communication bus 11. The bandwidth RA of the communication bus 11 is the maximum amount of data that can be transmitted over the communication bus 11 per unit time. The bandwidth RA includes a first bandwidth RA1 and a second bandwidth RA2. The sizes of the first bandwidth RA1 and the second bandwidth RA2 are determined during the configuration stage of the system 10.

[0017] The first bandwidth RA1 is a data capacity reserved for transmitting the static messages MG1. The first bandwidth RA1 is set so that the total data length of the static messages MG1 transmitted to the communication bus 11 per unit time does not exceed the first bandwidth RA1.

[0018] The second bandwidth RA2 is the data capacity reserved for transmitting the dynamic messages MG2. The bandwidth RA of the communication bus 11 excluding the first bandwidth RA1 is the second bandwidth RA2. As described above, the data length of the dynamic messages MG2 is predetermined. The second bandwidth RA2 is also predetermined. Therefore, it can be said that the upper limit of the number of dynamic messages MG2 that can be transmitted to the communication bus 11 per unit time is predetermined.

[0019] 4, for example, the second bandwidth RA2 is allocated to the plurality of ECUs 20. When a control program is updated or a control program is added in at least one of the plurality of ECUs 20, the amount of the second bandwidth RA2 allocated to the plurality of ECUs 20 is changed.

[0020] <Message sending process> 5, a series of processes executed by the CPU 22 to transmit the messages MG1 and MG2 to the communication bus 11 will be described. The CPU 22 repeatedly executes the series of processes at every predetermined control period.

[0021] In step S11, the CPU 22 determines whether or not there is a request to send a message. If there is a request to send a message (S11: YES), the CPU 22 proceeds to step S13. If there is no request to send a message (S11: NO), the CPU 22 temporarily ends the series of processes.

[0022] In step S13, the CPU 22 determines whether the message to be sent includes the dynamic message MG2. If the message to be sent includes the dynamic message MG2 (S13: YES), the CPU 22 proceeds to step S15. If the message to be sent does not include the dynamic message MG2 (S13: NO), the CPU 22 proceeds to step S23.

[0023] In step S15, the CPU 22 assigns a data ID to the generated dynamic message MG2. For example, the CPU 22 adds information indicating the data ID to the data field DT2 of the generated dynamic message MG2.

[0024] In the following step S17, the CPU 22 acquires the unsent number N, which is the number of dynamic messages MG2 that have not yet been transmitted to the communication bus 11, from among the generated dynamic messages MG2. Then, the CPU 22 determines whether the unsent number N is greater than the upper limit NL.

[0025] The "upper limit NL" here is an upper limit on the number of dynamic messages MG2 transmitted per unit time, which is set for the ECU 20 that is executing the series of processes shown in Fig. 5. The data length of the dynamic messages MG2 is fixed. Therefore, the larger the bandwidth of the second bandwidth RA2 allocated to the ECU 20, the larger the value set for the upper limit NL.

[0026] If the number of unsent messages N is greater than the upper limit NL (S17: YES), the CPU 22 proceeds to step S19. If the number of unsent messages N is equal to or less than the upper limit NL (S17: NO), the CPU 22 proceeds to step S23.

[0027] In step S19, the CPU 22 adjusts the number of dynamic messages MG2 to be transmitted to the communication bus 11 per unit time. Specifically, the CPU 22 determines the same number of dynamic messages MG2 as the upper limit NL from among the plurality of untransmitted dynamic messages MG2. In the next step S21, the CPU 22 adds an untransmitted flag to the dynamic messages MG2 that have been decided to be transmitted. The untransmitted flag is an example of information indicating that there are dynamic messages MG2 that have not yet been transmitted. For example, the CPU 22 sets an untransmitted flag in the data area DT2 of the dynamic messages MG2 that have been decided to be transmitted. Then, the CPU 22 proceeds to step S23.

[0028] In step S23, the CPU 22 transmits the message to be transmitted to the communication bus 11. That is, by performing the processes of steps S19 and S23, the CPU 22 can adjust the transmission of dynamic messages MG2 to the communication bus 11 so that the number of dynamic messages MG2 transmitted to the communication bus 11 per unit time does not exceed the upper limit NL. When the CPU 22 completes the transmission of the message, it temporarily ends the series of processes.

[0029] <Setting the upper limit NL> The flow of processing when setting the upper limit NL will be described with reference to FIG. 6. One of the multiple ECUs 20 functions as a master ECU 20A. The ECUs of the multiple ECUs 20 other than the master ECU 20A function as slave ECUs 20B. The master ECU 20A has a function of allocating the second bandwidth RA2 to the multiple ECUs 20, while the slave ECU 20B does not have this function. For ease of understanding, FIG. 6 illustrates only one of the multiple slave ECUs 20B.

[0030] When a control program is updated or a control program is added in at least one of the plurality of ECUs 20, the process shown in FIG. 6 starts. First, in step ST101, the CPU 22 in the master ECU 20A analyzes the updated or added service. Specifically, the CPU 22 checks whether the types of dynamic messages MG2 transmitted from the ECU 20 to the communication bus 11 will increase.

[0031] In the next step ST103, the CPU 22 in the master ECU 20A executes allocation processing of the second bandwidth RA2 based on the analysis result in step ST101. For example, the CPU 22 allocates the second bandwidth RA2 to the plurality of ECUs 20 so that the allocation to the ECU 20 having an increased number of types of dynamic messages MG2 to be transmitted to the communication bus 11 increases.

[0032] Then, in step ST105, the CPU 22 in the master ECU 20A notifies the slave ECU 20B of the bandwidth allocated to the slave ECU 20B out of the second bandwidth RA2.

[0033] In the subsequent step ST107, the CPU 22 in each of the master ECU 20A and the slave ECU 20B sets the upper limit NL in accordance with the allocation of the second bandwidth RA2 to the master ECU 20A and the slave ECU 20B. Specifically, the CPU 22 increases the upper limit NL as the allocation of the second bandwidth RA2 to the master ECU 20A and the slave ECU 20B increases.

[0034] <Actions and Effects of This Embodiment> (1-1) Each of the plurality of ECUs 20 sets an upper limit NL of the number of dynamic messages MG2 to be transmitted to the communication bus 11 per unit time to the number of dynamic messages MG2 that can be transmitted within the amount of the second bandwidth RA2 allocated to that ECU. Then, each of the plurality of ECUs 20 adjusts the transmission of dynamic messages MG2 to the communication bus 11 so that the number of dynamic messages MG2 transmitted to the communication bus 11 per unit time does not exceed the upper limit NL.

[0035] This prevents the plurality of ECUs 20 from transmitting a number of messages to the communication bus 11 that exceeds the bandwidth RA of the communication bus 11. This prevents the communication load of the system 10 from becoming excessive. Furthermore, the system 10 ensures a first bandwidth RA1 for transmitting static messages MG1. Therefore, even if the number of types of dynamic messages MG2 to be transmitted increases, the static messages MG1 can be transmitted and received between the plurality of ECUs 20. Therefore, the system 10 can prevent a decrease in communication quality even if the number of types of dynamic messages MG2 to be transmitted and received between the plurality of ECUs 20 increases.

[0036] (1-2) When the number of unsent dynamic messages MG2 among the generated dynamic messages MG2 is greater than the upper limit NL, each of the plurality of ECUs 20 adds an unsent flag to the dynamic messages MG2 to be transmitted when transmitting some of the unsent dynamic messages MG2 to the communication bus 11. Then, each of the plurality of ECUs 20 transmits the dynamic messages MG2 with the unsent flag added to the communication bus.

[0037] This allows the ECU 20, which has received the dynamic message MG2, to recognize that there is a dynamic message MG2 that has not yet been transmitted. In other words, the ECU 20 can recognize that the content of the dynamic message MG2 that has just been received may not be the latest.

[0038] (Second embodiment) A second embodiment of the communication network system will be described with reference to Fig. 7. The second embodiment differs from the first embodiment in that it is possible to delete some of the unsent dynamic messages. In the following description, differences from the first embodiment will be mainly described, and the same reference numerals will be used to designate the same components as those in the first embodiment, and redundant description will be omitted.

[0039] In each of the ECUs 20 of the system 10 of this embodiment, a dynamic message MG2 that satisfies a predetermined deletion condition is deleted from among the untransmitted dynamic messages MG2. That is, the dynamic message MG2 that satisfies the predetermined deletion condition is deleted from the ECU 20 without being transmitted to the communication bus 11.

[0040] <Dynamic message deletion process> A series of processes executed by the CPU 22 to delete the dynamic message MG2 will be described with reference to Fig. 7. The CPU 22 repeatedly executes the series of processes at predetermined control cycles.

[0041] In step S31, the CPU 22 determines whether or not there is a dynamic message MG2 among the dynamic messages MG2 that have not been sent, the time TM that has elapsed since the message was generated exceeds a predetermined time TMth. The longer the elapsed time TM, the older the content of the dynamic message MG2 is considered to be. Therefore, the predetermined time TMth is set as a criterion for determining whether the content of the dynamic message MG2 is old.

[0042] If there is a dynamic message MG2 whose elapsed time TM exceeds the predetermined time TMth (S31: YES), the CPU 22 proceeds to step S33. If there is no dynamic message MG2 whose elapsed time TM exceeds the predetermined time TMth (S31: NO), the CPU 22 temporarily ends the series of processes.

[0043] In step S33, the CPU 22 deletes the dynamic message MG2 whose elapsed time TM exceeds the predetermined time TMth, and then the CPU 22 temporarily ends the series of processes. <Actions and Effects of This Embodiment> In the system 10 of this embodiment, in addition to the effects of the first embodiment, the following effects can be further obtained.

[0044] (2-1) Each of the plurality of ECUs 20 deletes a dynamic message MG2 that has not been transmitted to the communication bus 11 even when the elapsed time TM since its generation exceeds a predetermined time TMth. This prevents old dynamic messages MG2 from being transmitted to other ECUs 20 in the system 10.

[0045] (Example of change) The above-described embodiments can be modified as follows: The above-described embodiments and the following modifications can be combined with each other within the scope of technical compatibility.

[0046] In the above-described embodiments, the CPU 22 does not have to add an unsent flag to the dynamic message MG2 to be transmitted to the communication bus 11. The number of ECUs constituting the system 10 may be three or more, as long as it is two or more.

[0047] The ECU 20 is not limited to one that includes a CPU and a ROM and executes software processing. That is, the ECU 20 may have any one of the following configurations (a), (b), and (c):

[0048] (a) The ECU 20 includes one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions that cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0049] (b) The ECU 20 includes one or more dedicated hardware circuits that perform various processes. Examples of the dedicated hardware circuits include application-specific integrated circuits (ASICs) and FPGAs. ASIC stands for "Application Specific Integrated Circuit," and FPGA stands for "Field Programmable Gate Array."

[0050] (c) The ECU 20 includes one or more processors that execute some of the various processes in accordance with computer programs, and one or more dedicated hardware circuits that execute the remaining processes among the various processes.

[0051] The expression "at least one" used herein means "one or more" of the desired options. As an example, the expression "at least one" used herein means "only one option" or "both of two options" if the number of options is two. As another example, the expression "at least one" used herein means "only one option" or "any combination of two or more options" if the number of options is three or more. [Explanation of symbols]

[0052] 10...communication network system (system), 11...communication bus, 20...electronic control unit (ECU), 21...processing circuit.

Claims

1. 1. A communication network system comprising a plurality of electronic control devices configured to transmit and receive static and dynamic messages over a communication bus, a total data length of the static messages transmitted to the communication bus per unit time does not exceed a first bandwidth of the communication bus; a second bandwidth of the communication bus excluding the first bandwidth is allocated to the plurality of electronic control devices as a bandwidth for communication of the dynamic message; Each of the plurality of electronic control devices setting an upper limit on the number of the dynamic messages to be transmitted to the communication bus per unit time to the number of the dynamic messages that can be transmitted within the second bandwidth allocated to the device; adjusting the transmission of the dynamic messages to the communication bus so that the number of the dynamic messages transmitted to the communication bus per unit time does not exceed the upper limit. Communication network system.

2. Each of the plurality of electronic control devices When the number of the generated dynamic messages that have not yet been transmitted to the communication bus is greater than the upper limit, and when some of the untransmitted dynamic messages are to be transmitted to the communication bus, the dynamic messages to be transmitted are transmitted to the communication bus with information added thereto indicating that there are dynamic messages that have not yet been transmitted. The communication network system according to claim 1 .

3. Each of the plurality of electronic control devices deletes the dynamic message that has not been transmitted to the communication bus even when a predetermined time has elapsed since the message was generated.

3. The communication network system according to claim 1 or 2.

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