Vehicle communication system, vehicle communication method, and control device
A vehicle communication system includes a plurality of ECUs connected by the communication network including a plurality of communication transmission lines. Each of the ECUs includes an identification unit that identifies a target ECU to be a communication partner, and a relay transmission line and a relay ECU through which communication with the target ECU is routed, a standby time determination unit that determines a transmission standby time based on information on the relay ECU, the transmission standby time being a time from transmission of an activation instruction to another one of the ECUs closest to the ECU along the relay transmission line to transmission of a control signal toward the target ECU, and a communication unit that transmits the control signal after an elapse of the transmission standby time after transmitting the activation instruction to the relay transmission line closest to the ECU.
1 . A vehicle communication system mounted on a vehicle, the vehicle communication system comprising:
a communication network including a plurality of communication transmission lines; and
a plurality of electronic control units (ECUs) connected by the communication network,
wherein each one of the ECUs includes:
an identification unit that identifies a single target ECU, and a relay transmission line and a relay ECU based on an input signal or input information, the target ECU being another one of the ECUs and being a target to which a control signal is to be transmitted, the relay transmission line and the relay ECU being a communication transmission line and still another one of the ECUs, respectively, through which the control signal toward the target ECU is routed,
a standby time determination unit that determines a transmission standby time, the transmission standby time being a time from transmission of an activation instruction for whichever is closest of the relay ECU or the target ECU along the relay transmission line to the transmission of the control signal, and
a communication unit that transmits the control signal after an elapse of the transmission standby time after transmitting the activation instruction to a relay transmission line after transmitting the activation instruction to a relay transmission line directly connected to the communication unit and without transmitting the activation instruction to a relay transmission line connected to the communication unit through another ECU,
wherein the communication transmission lines include:
a synchronous communication bus that allows communication to start synchronously between all ECUs connected to the synchronous communication bus, and
an asynchronous communication bus that allows communication to start asynchronously between ECUs connected to the asynchronous communication bus, and
wherein when the directly connected relay transmission line is the asynchronous communication bus, the communication unit repeatedly sends out, to the asynchronous communication bus, the activation instruction to which is closest of the relay ECU or the target ECU at predetermined time intervals.
2 . The vehicle communication system according to claim 1 , wherein when the communication unit receives an activation instruction transmitted by another one of the ECUs as an input signal or input information and repeatedly transmits an activation instruction to the asynchronous communication bus based on the input signal or input information, the communication unit causes an ECU as a transmission source of the received activation instruction to wait to transmit the control signal until the transmission standby time elapses after the activation instruction is transmitted to the asynchronous communication bus.
3 . The vehicle communication system according to claim 1 , wherein the standby time determination unit determines the transmission standby time based on an activation time of whichever is closest of the relay ECU or the target ECU along the relay transmission line.
4 . A vehicle communication method executed by a computer of one control device mounted on a vehicle, a plurality of control devices being connected to each other by a communication network including a plurality of communication transmission lines to constitute a vehicle communication system, the method comprising the steps of:
identifying a single target electronic control unit (ECU), and a relay transmission line and a relay ECU based on an input signal or input information, the target ECU being another one of the control devices and being a target to which a control signal is to be transmitted, the relay transmission line and the relay ECU being the communication transmission line and still another one of the control devices, respectively, through which the control signal toward the target ECU is routed;
determining a transmission standby time, the transmission standby time being a time from transmission of an activation instruction for whichever is closest of the relay ECU or the target ECU along the relay transmission line to transmission of the control signal; and
transmitting the control signal after an elapse of the transmission standby time after transmitting the activation instruction to a relay transmission line directly connected to the one control device and without transmitting the activation instruction to a relay transmission line connected to the one control device through another ECU,
wherein the communication transmission lines include a synchronous communication bus that allows communication to start synchronously between all the ECUs connected to the synchronous communication bus, and an asynchronous communication bus that allows communication to start asynchronously between the ECUs connected to the asynchronous communication bus, and the method further comprises the step of, when the directly connected relay transmission line is the asynchronous communication bus, repeatedly sending out, to the asynchronous communication bus, the activation instruction whichever is closest of the relay ECU or the target ECU at predetermined time intervals.
5 . A control device mounted on a vehicle, the control device being one control device, a plurality of control devices being connected to each other by a communication network including a plurality of communication transmission lines to constitute a vehicle communication system, each of the control devices comprising:
an identification unit that identifies a single target electronic control unit (ECU), and a relay transmission line and a relay ECU based on an input signal or input information, the target ECU being another one of the control devices and being a target to which a control signal is to be a transmitted, the relay transmission line and the relay ECU being the communication transmission line and still another one of the control devices, respectively, through which the control signal toward the target ECU is routed;
a standby time determination unit that determines a transmission standby time, the transmission standby time being a time from transmission of an activation instruction for whichever is closest of the relay ECU or the target ECU along the relay transmission line to transmission of the control signal; and
a communication unit that transmits the control signal after an elapse of the transmission standby time after transmitting the activation instruction to a relay transmission line directly connected to the one control device and without transmitting the activation instruction to a relay transmission line connected to the one control device through another ECU,
wherein the communication transmission lines include;
a synchronous communication bus that allows communication to start synchronously between all the ECUs connected to the synchronous communication bus, and
an asynchronous communication bus that allows communication to start asynchronously between the ECUs connected to the asynchronous communication bus, and
wherein when the directly connected relay transmission line is the asynchronous communication bus, the communication unit repeatedly sends out, to the asynchronous communication bus, the activation instruction to whichever is closest of the relay ECU or the target ECU at predetermined time intervals.