Patent ID: 12255757

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

First, embodiments of the present disclosure will be listed and described. Also, at least parts of the embodiments described below can be freely combined.

A relay device system according to one aspect of this disclosure is a relay device system to be installed in a vehicle, the relay device system including a wireless relay device configured to wirelessly communicate with a communication device provided outside the vehicle, a plurality of wired relay devices that are connected in a ring to the wireless relay device, and an in-vehicle network that is formed in a ring by a communication line connecting the wireless relay device and the plurality of wired relay devices, in which the plurality of wired relay devices each include an ECU communication unit configured to communicably connect to an ECU for controlling an on-board device installed in the vehicle, and the wireless relay device and the plurality of wired relay devices are configured to communicate with each other through the in-vehicle network, using two clockwise and counterclockwise paths.

In this aspect, the wireless relay device and the plurality of wired relay devices communicate with each other through the in-vehicle network formed in a ring, using two clockwise and counterclockwise paths. Therefore, even if any of the communication lines is disconnected and one of the paths is interrupted, for example, it is possible to continue communication between the wireless relay device and the plurality of wired relay devices, and to improve the redundancy of communication between inside and outside of the vehicle.

In the relay device system according to one aspect of this disclosure, the wireless relay device and the wired relay devices each include a first wired communication unit that corresponds to a clockwise side of the in-vehicle network, and a second wired communication unit that corresponds to a counterclockwise side of the in-vehicle network, and the ring-like in-vehicle network is formed by connecting the first wired communication unit of any one of the wireless relay device and the wired relay devices and the second wired communication unit of the wireless relay device or the wired relay device that is directly connected to the one relay device to each other by the communication line.

In this aspect, it is possible to easily form a ring-like in-vehicle network by connecting the first wired communication unit of any one of the wireless relay device and the wired relay devices and the second wired communication unit of the wireless relay device or the wired relay devices that is directly connected to the one relay device to each other by the communication line.

In the relay device system according to one aspect of this disclosure, the wireless relay device includes a control unit configured to control communication with the wired relay devices, and the wireless relay device is configured to communicate with the wired relay devices with use of either a predetermined clockwise or counterclockwise path in the in-vehicle network, and, if the control unit has detected an abnormality in communication via the predetermined path, the control unit communicates with the wired relay devices with use of a path that is different from the predetermined path.

In this aspect, if an abnormality in communication with the wired relay devices via a predetermined path is detected, the control unit of the wireless relay device communicates with the wired relay devices using a path that is different from the predetermined path, that is, a path extending in a direction opposite to that of the predetermined path, and thus it is possible to improve the redundancy of communication between inside and outside of the vehicle.

In the relay device system according to one aspect of this disclosure, the wireless relay device includes a control unit configured to control communication with the wired relay devices, and the control unit is configured to acquire information regarding the path to be used in communication with the wired relay devices, and determine a path of communication with the wired relay devices based on the acquired information regarding the path, and, if the control unit has detected an abnormality in communication via the determined path, the control unit modifies the information regarding the path so as to use a different path from the determined path.

In this aspect, if an abnormality in communication with the wired relay devices is detected depending on the path determined based on acquired information, the control unit of the wireless relay device modifies the information (path information) regarding the path so as to use a different path from the determined path. Therefore, after an abnormality has been detected in communication with the wired relay devices, the wireless relay device communicates with the wired relay devices via a path determined based on the modified information, and thus it is possible to improve the redundancy of communication between inside and outside of the vehicle.

In the relay device system according to one aspect of this disclosure, the ECU includes a self-driving-related ECU, and an HMI-related ECU, and the self-driving-related ECU is connected to the ECU communication unit of one of the two wired relay devices that are directly connected on the clockwise side and the counterclockwise side of the wireless relay device, and the HMI-related ECU is connected to the ECU communication unit of the other of the two wired relay devices.

In this aspect, the wired relay device that is connected to the self-driving-related ECU and the wired relay device that is connected to the HMI-related ECU are directly connected to the wireless relay device. The wired relay device that is connected to the self-driving-related ECU and the wireless relay device are directly connected to each other, and the communication quality of information regarding self-driving is secured by reducing the number of hops (the number of relays) in communication between the self-driving-related ECU and a communication device provided outside the vehicle, and thereby safety regarding self-driving can be improved. Also, by directly connecting the wired relay device that is connected to the HMI-related ECU and the wireless relay device to each other, other wired relay devices need not relay large volume data such as moving image data or streaming data that is communicated between the HMI-related ECU and a communication device provided outside the vehicle.

The following specifically describes the present disclosure based on the drawings illustrating embodiments thereof. A relay device system S according to embodiments of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is indicated by the scope of the claims, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Embodiment 1

FIG.1is a schematic diagram showing a configuration of the relay device system S according to Embodiment 1. The relay device system S is installed in a vehicle1, and includes a wireless relay device10and three wired relay devices20.

Each of the wireless relay device10and the three wired relay devices20are communicably connected to another relay device (the wireless relay device10or a wired relay device20) located on both the clockwise side and the counterclockwise side thereof, via a communication line3such as an Ethernet (registered trademark) cable or the like, for example. That is, a ring-like in-vehicle network4(ring network topology) is constituted due to the wireless relay device10and the three wired relay devices20being connected to each other via the communication lines3. Note that the number of wired relay devices20is three, but is not limited thereto. The number of wired relay devices20need only be two or more, as long as the number of relay devices including the wired relay devices20and the wireless relay device10is three or more, and the ring-like in-vehicle network4can be formed by these relay devices (the wired relay devices20and the wireless relay device10).

The wireless relay device10is connected to an external antenna100for wirelessly communicating with communication devices (not shown) outside the vehicle. The wireless relay device10wirelessly communicates with communication devices outside the vehicle, and transmits (relays) various types of data received through this wireless communication to the wired relay devices20. The wireless relay device10relays communication between communication devices outside the vehicle and later-described ECUs (Electronic Control Units) installed in the vehicle. Also, the wireless relay device10relays communication between the two wired relay devices20that are directly connected to thereto.

The plurality of wired relay devices20are communicably connected to ECUs (self-driving-related ECUs31, HMI-related ECUs32, and travel control-related ECUs33) that control on-board devices via ECU wiring2such as a CAN (Controller Area Network/registered trademark) cable or an Ethernet cable. Note that the ECUs that are each connected to one of the plurality of wired relay devices20are not limited to the self-driving-related ECUs31, the HMI-related ECUs32, or the travel control-related ECUs33, and may be body-related ECUs for controlling the driving of a door mirror or a seat, for example, and various ECUs installed in the vehicle1are connected to these multiple wired relay devices20.

The HMI-related ECUs32are connected to the wired relay device20that is directly connected on the clockwise side of the wireless relay device10. The self-driving-related ECUs31are connected to the wired relay device20that is directly connected on the counterclockwise side of the wireless relay device10. The travel control-related ECUs33are connected to the wired relay device20connected between the wired relay device20for the HMI-related ECUs32and the wired relay device20for the self-driving-related ECUs31.

Each wired relay device20relays communication between the wireless relay device10or the other wired relay devices20directly connected on the clockwise side and the counterclockwise side thereof. Also, each wired relay device20relays information transmitted from the wireless relay device10or another wired relay device20, and transmits the information to the ECUs that are directly connected thereto. Each wired relay device20relays information transmitted from the ECUs that are directly connected thereto, and transmits the information to the wireless relay device10or another wired relay device20.

The wireless relay device10is located in a central portion of the vehicle1, and is provided on the roof of the vehicle1, and accordingly, the external antenna100connected to the wireless relay device10can favorably receive radio waves. The wired relay device20that is connected to the self-driving-related ECUs31is provided in a rear portion of the vehicle1. The wired relay device20that is connected to the HMI-related ECUs32is provided in a front portion of the vehicle1on the opposite side to a driver's seat5, such as inside an instrument panel (dashboard), for example. The wired relay device20that is connected to the travel control-related ECUs33is provided in the front portion of the vehicle1on the driver's seat5side, such as inside the instrument panel (dashboard), for example. By arranging each wired relay device20as close as possible to the ECUs that are connected thereto in this manner, it is possible to simplify routing, such as by shortening the wiring length of the ECU wiring2connecting the wired relay device20and the ECUs.

FIG.2is a block diagram showing configurations of the wireless relay device10and the wired relay devices20. The wireless relay device10includes a wireless communication unit101, a control unit105, a storage unit106, a first wired communication unit102, and a second wired communication unit103, and is connected to the external antenna100. Note that the wireless relay device10may include this external antenna100.

The wireless communication unit101is connected via a harness or the like to the external antenna100for wirelessly communicating with communication devices outside the vehicle. The wireless communication unit101uses a predetermined wide-area communication standard such as 5G, 4G, LTE, or the like, to wirelessly communicate with communication devices outside the vehicle, and is a communication device known as a TCU (Telematics Communication Unit), for example.

The control unit105may be constituted by a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or the like, and performs various types of control processing and arithmetic processing by reading out and executing control programs and data previously stored on the storage unit106. The control unit105is communicably connected via an internal bus104to the wireless communication unit101, the first wired communication unit102, and the second wired communication unit103. The control unit105performs control to relay data to be communicated to the wireless communication unit101, the first wired communication unit102, and the second wired communication unit103by executing the control programs.

The control programs include security programs for ensuring the security of the wireless relay device10. The control unit105executes the security programs to exhibit security functions to handle unauthorized communication (attacks) from outside of the vehicle by way of, for example, DoS attacks or data containing viruses, worms, or the like, and thus ensure the security (secure a secure communication state) of the wireless relay device10.

The storage unit106is constituted by a volatile memory element such as RAM (Random Access Memory), or a non-volatile memory element such ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable ROM), or flash memory, and pre-stores control programs and data that is referenced when processing is performed. The control programs stored on the storage unit106may also be control programs that are read out from a recording medium (not shown) readable by the wireless relay device10and stored on the storage unit106. Also, the control programs may also be downloaded from an external computer (not shown) that is connected to a communication network (not shown) and stored on the storage unit106.

Path information for communicating with the plurality of wired relay devices20or the ECUs connected to the plurality of wired relay devices20is stored on the storage unit106in table form, for example. The path information includes addresses of the plurality of wired relay devices20and ECUs. Furthermore, the path information includes, as paths for transmitting (relaying) information to the plurality of wired relay devices20and the ECUs, a correspondence relationship as to which of the first wired communication unit102or the second wired communication unit103is to be used to transmit the information to the addresses of the plurality of wired relay devices20and the ECUs. Accordingly, by referencing the path information stored on the storage unit106, the control unit105can relay communication between the ECUs and communication devices outside the vehicle, or communication between the ECUs.

The first wired communication unit102and the second wired communication unit103are input-output I/Fs such as Ethernet communication ports, and the protocols of the physical layers thereof may be of IEEE standards such as 100BASE-T1 or 1000BASE-T1, for example. If the first wired communication unit102and the second wired communication unit103are Ethernet communication ports, for example, port numbers of communication ports are set (provided) to the first wired communication unit102and the second wired communication unit103. The port number of the first wired communication unit102is one, and the port number of the second wired communication unit103is two, for example. In the above-described path information stored on the storage unit106, the port number (1) of the first wired communication unit102or the port number (2) of the second wired communication unit103is set in correspondence with the addresses of the plurality of wired relay devices20and the ECUs (the port numbers are set in association with the addresses). Note that a port number for loopback (e.g., zero) may be set for the address of this wireless relay device10.

The wired relay devices20each include a first wired communication unit201, a second wired communication unit202, a control unit203, a storage unit204, and an ECU communication unit205. The control unit203of the wired relay device20has a configuration that is similar to that of the control unit105of the wireless relay device10described above. The control unit203of the wired relay device20is communicably connected to the first wired communication unit201, the second wired communication unit202, and the ECU communication unit205via an internal bus206. The control unit203performs control to relay data to be communicated to the first wired communication unit201, the second wired communication unit202, and the ECU communication unit205by reading out and executing control programs and data stored on the storage unit204.

The control programs of the wired relay device20may also include security programs for ensuring the security of the wired relay device20, similarly to the control programs of the wireless relay device10. The control unit203of the wired relay device20exhibits security functions to handle unauthorized communication (attacks) such as data containing viruses and thus ensure the security of the wired relay device20.

The storage unit204of the wired relay device20has a configuration that is similar to that of the storage unit106of the wireless relay device10described above. Path information for communicating with the wireless relay device10, the other wired relay devices20, or the ECUs is stored on the storage unit204of the wired relay device20in table form, for example, similarly to the storage unit106of the wireless relay device10. The path information includes the addresses of the wireless relay device10, the plurality of wired relay devices20, and the ECUs. Furthermore, the path information includes a correspondence relationship as to which of the first wired communication unit201and the second wired communication unit202is to be used to transmit (relay) the information to the addresses of the wireless relay device10, the plurality of wired relay devices20, and ECUs, as paths for transmitting (relaying) information to the wireless relay device10, the plurality of wired relay devices20, and the ECUs.

The plurality of wired relay devices20and the wireless relay device10function as a layer2switch or a layer3switch, for example. If the plurality of wired relay devices20and the wireless relay device10function as a layer2switch, the MAC addresses of the plurality of wired relay devices20, the wireless relay device10, and the ECUs are stored on the storage unit204as path information. If the plurality of wired relay devices20and the wireless relay device10function as a layer3switch, the IP addresses of the plurality of wired relay devices20, the wireless relay device10, and the ECUs are stored on the storage unit204as path information. Accordingly, by referencing the path information stored on the storage unit204, the control unit203of the wired relay device20can relay communication between the ECUs connected to this wired relay device20and communication devices outside the vehicle, or communication between the ECUs connected to this wired relay device20and the ECUs connected to other wired relay devices20.

The first wired communication unit201and the second wired communication unit202of the wired communication unit20are input-output I/Fs such as Ethernet communication ports that conform to standards similar to those of the first wired communication unit102and the second wired communication unit103of the wireless relay device10, and the protocols of physical layers may be 100BASE-T1 or 1000BASE-T1, for example.

The first wired communication unit201of the wired relay device20that is directly connected on the counterclockwise side of the wireless relay device10and the second wired communication unit103of the wireless relay device10are connected by the communication line3via an Ethernet cable such as that of 100BASE-T1 or 1000BASE-T1, for example. The second wired communication unit202of the wired relay device20that is directly connected on the clockwise side of the wireless relay device10and the first wired communication unit102of the wireless relay device10are connected by the communication line3in a similar manner. The wired relay device20that is not directly connected to the wireless relay device10is connected to the other wired relay devices20that are directly connected on the clockwise side and the counterclockwise side via the first wired communication unit201(on the clockwise side) and the second wired communication unit202(on the counterclockwise side). That is, the first wired communication unit201(on the clockwise side) of the wired relay device20that is not directly connected to the wireless relay device10and the second wired communication unit202(on the counterclockwise side) of the other wired relay device20that is directly connected on the clockwise side of this wired relay device20are connected to each other via the communication line3. The second wired communication unit202(on the counterclockwise side) of the wired relay device20that is not directly connected to the wireless relay device10and the first wired communication unit201(on the clockwise side) of the other wired relay device20that is directly connected on the clockwise side of this wired relay device20are connected to each other via the communication line3.

The ECUs are connected to a corresponding one of the plurality of wired relay devices20via the respective ECU communication units205. The ECUs are constituted by programs for controlling the corresponding on-board devices and microcomputers and the like for executing the programs. As shown inFIG.1, each of the ECUs (the self-driving-related ECUs31, the HMI-related ECUs32, and the travel control-related ECUs33) is connected to one of the wired relay devices20according to the priority level of that ECU regarding traveling safety.

FIG.3is an illustrative diagram regarding priority levels of the ECUs regarding traveling safety. The priority levels of the ECUs (the self-driving-related ECUs31, the HMI-related ECUs32, and the travel control-related ECUs33) regarding the traveling safety of the vehicle1are determined based on the corresponding on-board devices and the functions of the programs to be executed, and may be determined based on, for example, ASIL (Automotive Safety Integrity Level) in ISO26262. As shown inFIG.3, the ASIL levels are classified into levels QM, ASIL-A, ASIL-B, ASIL-C, and ASIL-D. The QM level is normal quality management in which it is not necessary to apply functional safety according to ISO26262. The ASIL-A to ASIL-D levels are levels at which functional safety needs to be applied in accordance ISO26262, and the functional safety requirements become stricter from ASIL-A to ASIL-D. That is, the QM level can be regarded as the lowest priority level, and the ASIL-D level can be regarded as the highest priority level.

As the ECUs corresponding to the ASIL levels, for example, ECUs that correspond to the QM level may be HMI (Human Machine Interface)-related ECUs32that control or process entertainment-related data such as moving image data or streaming data handled by an HMI device such as car navigation and TV. ECUs that correspond to the ASIL-A level are body-related ECUs that control the positions of the seats, control the door mirrors, or the like. The ECUs that correspond to the ASIL-B level are travel control-related ECUs33related to control such as driving control of engines, motors, or the like. The ECUs corresponding to the ASIL-C level are travel control-related ECUs33related to control such as steering wheel control or brake control. The ECUs corresponding to the ASIL-D level are self-driving-related ECUs31related to self-driving control.

Alternatively, the priority levels of the ECUs regarding the traveling safety of the vehicle1are set such that the priority level of the self-driving-related ECUs31is the highest, the priority level of the ECUs that perform control related to the turning or stopping of the vehicle1is the next highest, and the priority level of the ECUs that perform control related to the traveling (running) of the vehicle1is the next highest. Configurations are also possible in which the priority level of ECUs that perform control other than the forms of control mentioned above, such an HMI-related ECUs32that control HMI-related devices, is the lowest.

As described above, the ECUs (the self-driving-related ECUs31, the HMI-related ECUs32, and the travel control-related ECUs33) are connected to a corresponding one of the plurality of wired relay devices20. The self-driving-related ECUs31are connected to the wired relay device20that is directly connected on the counterclockwise side of the wireless relay device10. The travel control-related ECUs33are connected to the wired relay device20that is not directly connected to the wireless relay device10. That is, the wired relay device20that is connected to the self-driving-related ECUs31is a wired relay device having a higher priority level regarding the traveling safety of the vehicle1than that of the wired relay device20that is connected to the travel control-related ECUs33. By directly connecting the wired relay device20having a higher priority level regarding the traveling safety of the vehicle1to the wireless relay device10in this manner, it is possible to reduce the number of hops (the number of relays) in communication between communication devices outside the vehicle and the ECU having a higher priority level regarding the traveling safety of the vehicle1, such as the self-driving-related ECUs31, and, to secure communication quality.

The HMI-related ECUs32are connected to the wired relay device20that is directly connected on the clockwise side of the wireless relay device10. Large volume data such as moving image data or streaming data is transmitted and received between a display device under the control of the HMI-related ECUs32and communication devices outside the vehicle, for example. By directly connecting the wired relay device20that is connected to the HMI-related ECUs32to the wireless relay device10, it is possible to suppress the flow of large volume data to the other wired relay devices20, and to eliminate processing in which the other wired relay devices20relay large volume data.

The respective control units105and203of the wireless relay device10and the plurality of wired relay devices20acquire information transmitted from communication devices outside the vehicle or the other relay devices (the wireless relay device10or the wired relay devices20), and reference path information respectively stored on the storage units106and204based on the destination addresses included in the information. The control units105and203determine, based on the referenced path information, whether to use a clockwise (the first wired communication units102and201) path or a counterclockwise (the second wired communication units103and202) path in the in-vehicle network4forming a ring. Alternatively, the respective control units105and203of the wireless relay device10and the plurality of wired relay devices20may derive predetermined paths decided in advance and are respectively stored on the storage units106and204, based on the destination addresses included in this information. The respective control units105and203of the wireless relay device10and the plurality of wired relay devices20relay information by transmitting the acquired information via the determined or derived paths (clockwise or counterclockwise).

If the respective control units105and203of the wireless relay device10and the plurality of wired relay devices20have detected an abnormality in communication with the other relay devices, such as failure of normal transmission of the information transmitted via the paths, the control units105and203communicate with the other relay devices via paths that are different from the determined or derived paths. That is, if the determined or derived path is clockwise, when the respective control units105and203of the wireless relay device10and the plurality of wired relay devices20have detected an abnormality in the clockwise path, the control units105and203communicate with the other relay devices via the counterclockwise path. If the determined or derived path is counterclockwise, when the respective control units105and203of the wireless relay device10and the plurality of wired relay devices20detect an abnormality in the counterclockwise path, the control units105and203communicate with the other relay devices via a clockwise path.

If the respective control units105and203of the wireless relay device10and the plurality of wired relay devices20have detected an abnormality in communication via the determined or derived path, the control units105and203may modify path information that is stored on the respective storage units106and204. The path information is stored with the path corresponding to the address of the wired relay device20or the like serving as the destination as the first wired communication units102and201, for example, and if an abnormality has been detected in communication with that wired relay device20via the first wired communication units102and201, the respective control units105and203modify the path corresponding to the address of that wired relay device20to the second wired communication units103and202. The path information that is respectively stored on the storage units106and204is rewritten by modifying this path.

The respective control units105and203of the wireless relay device10and the plurality of wired relay devices20detect an abnormality in communication with other relay devices (the wireless relay device10or the wired relay devices20) due to whether or not there is a reply to transmitted information, for example. The method for detecting an abnormality in communication is not limited thereto, and the respective control units105and203of the wireless relay device10and the plurality of wired relay devices20may periodically perform polling with the wireless relay device10or the wired relay devices20that is directly connected thereto, and detect an abnormality in communication based on the results of this polling, for example. Alternatively, the respective control units105and203of the wireless relay device10and the plurality of wired relay devices20may detect carrier sense in the first wired communication units102and201or the second wired communication units103and202. Then, the control units105and203may detect disconnection of the communication line3connected to the first wired communication units102and201or the second wired communication units103and202based on whether or not the detected carrier sense has a predetermined voltage value, and thus detect an abnormality in communication. Furthermore, the respective control units105and203of the wireless relay device10and the plurality of wired relay devices20may store the location where this abnormality has occurred in the storage units106and204of these relay devices, based on the results of detection of abnormalities in communication. The location where the abnormality has occurred is specified as being between the relay device that detected the abnormality and the other relay device (the wireless relay device10or the wired relay devices20) that is directly connected thereto. Alternatively, the location where the abnormality has occurred may be specified as being between relay devices (the wireless relay device10or the wired relay devices20) that are specified by MAC addresses or IP addresses, for example. Also, the wireless relay device10may transmit information regarding the results of detection of abnormalities in communication, including information regarding the location where the abnormality has occurred in communication, to a communication device outside the vehicle via the wireless communication unit101. As a result of storing, in the storage units106and204, information regarding the results of detection of abnormalities in communication, including information regarding the location where abnormalities occur in communication, the respective control units105and203of the wireless relay device10and the plurality of wired relay devices20can efficiently perform control regarding communication paths based on the stored information.

The respective control units105and203of the wireless relay device10and the plurality of wired relay devices20detect an abnormality in communication with other relay devices (the wireless relay device10or the wired relay devices20) in this manner. Furthermore, the control units105and203change the paths for communicating with the other relay devices (the wireless relay device10or the wired relay devices20) or modify path information according to the results of detection, and thus it is possible to improve and secure the redundancy of communication between the wireless relay device10and the plurality of wired relay devices20connected to the in-vehicle network4formed in a ring. By securing the redundancy of communication between the wireless relay device10and the plurality of wired relay devices20connected to the in-vehicle network4, it is possible to improve and secure the redundancy of communication with the ECUs that are respectively connected to the wired relay devices20and communication devices outside the vehicle.

FIG.4is a flowchart showing processing performed by the control unit105according to Embodiment1(different path). The control unit105of the wireless relay device10performs the following processing based on a predetermined input signal that is input regularly or in cases such as where the ignition switch (IG switch) is turned on.

The control unit105of the wireless relay device10acquires information to be relayed from a communication device outside the vehicle or a wired relay device20, which is another relay device (step S01). The control unit105acquires information transmitted from a communication device outside the vehicle via the wireless communication unit101. Alternatively, the control unit105acquires information transmitted from the wired relay device20that is directly connected on the clockwise side or the counterclockwise side of the wireless relay device10via the first wired communication unit102or the second wired communication unit103. This information is information to be relayed to a wired relay device20or an ECU that is connected to a wired relay device20.

The control unit105of the wireless relay device10transmits information via a predetermined path based on the acquired information (step S02). The control unit105references the destination address included in a header portion in the acquired information, for example, and derives a predetermined path. The control unit105references the path information stored on the storage unit, and derives the path corresponding to the destination address, that is, the path through which to communicate via the first wired communication unit102or the second wired communication unit103. Alternatively, the control unit105may derive a predetermined path without referencing the path information, by using a default setting according to all acquired information is to be transmitted on a path via either the first wired communication unit102or the second wired communication unit103.

The control unit105of the wireless relay device10detects whether or not an abnormality has occurred in communication via the predetermined path (step S03). The control unit105detects whether or not an abnormality has occurred in communication via the derived predetermined path, and determines whether or not an abnormality has occurred, based on the results of detection. If the control unit105of the wireless relay device10has transmitted information via the predetermined path and then has not received a reply to this transmission in a predetermined period of time, for example, the control unit105detects an abnormality in communication via the predetermined path.

If an abnormality has been detected (YES in step S03), the control unit105of the wireless relay device10retransmits the information via a path that is different from the predetermined path derived in step S02(step S04). That is, if the predetermined path derived in step S02is a clockwise path (the first wired communication unit102), the control unit105performs communication via a counterclockwise path (the second wired communication unit103), and retransmits the information that failed to transmit in step S02. The control unit105performs loop processing in order to perform the processing of step S01again after performing the processing of step S04, and continues the processing for relaying the acquired information.

If no abnormality has been detected (NO in step S03), that is, if communication is normally performed via the predetermined path, the control unit105of the wireless relay device10performs loop processing in order to perform processing of step S01again. If communication is normally performed via the predetermined path, the control unit105can continue processing for relaying the information by successively acquiring information to be relayed, and transmitting the information via the predetermined path.

Every time the control unit105of the wireless relay device10communicates with a wired relay device20, which is another relay device, the control unit105detects whether or not an abnormality occurs in communication, and if the control unit105has detected an abnormality, the control unit105resumes communication via a path that is different from the predetermined path decided in advance, and thereby, the redundancy of communication in the in-vehicle network4can be achieved. Also, this abnormality temporarily occurs, and after being resolved, it is possible to perform communication between the wireless relay device10and the wired relay devices20in the in-vehicle network4via the predetermined path decided in advance.

Note that, although the flow of the processing performed by the control unit105of the wireless relay device10has been described in this embodiment, there is no limitation thereto. The respective control units203of the plurality of wired relay devices20can also achieve the redundancy of communication in the in-vehicle network4by performing processing similar to that of the control unit105of the wireless relay device10.

Embodiment 2

FIG.5is a flowchart showing processing performed by the control unit105according to Embodiment 2 (modification of path information). The control unit105of the wireless relay device10performs the following processing based on an input signal that is input regularly or in cases such as when the ignition switch (IG switch) is turned on, in a manner similar to that of Embodiment 1. The control unit105of the wireless relay device10of Embodiment2is different from that of Embodiment 1 in terms of modifying path information.

Similarly to the processing (step S01) of Embodiment 1, the control unit105of the wireless relay device10acquires information to be relayed from a communication device outside the vehicle or a wired relay device20, which is another relay device (step S21).

The control unit105of the wireless relay device10transmits information via a path determined by referencing the path information (step S22). The control unit105references the path information stored on a storage unit106based on the destination address included in a header portion of the acquired information, and determines whether to use the clockwise (the first wired communication unit102) path or the counterclockwise (the second wired communication unit103) path in the ring-like in-vehicle network4.

The control unit105of the wireless relay device10detects whether or not an abnormality has occurred in communication via the determined path (step S23). The control unit105detects whether or not an abnormality has occurred in communication via the determined path, similarly to the processing of step S03in Embodiment 1, and determines whether or not an abnormality occurs, based on the results of detection.

If an abnormality has been detected (YES in step S23), the control unit105of the wireless relay device10modifies the path information and retransmits the information (step S24). If the control unit105has detected an abnormality in communication with a wired relay device20, which is another relay device, the control unit105modifies the path information so as to use a different path from the path set in the path information stored on the storage unit106. Therefore, after the control unit105has detected an abnormality, the control unit105can resume communication with the wired relay device20by referencing the modified path information. The control unit105performs loop processing in order to perform the processing of step S21again after performing the processing of step S24, and continues the processing for relaying the acquired information.

If no abnormality has been detected (NO in step S23), that is, if communication is normally performed via the predetermined path, the control unit105of the wireless relay device10performs loop processing in order to perform the processing of step S21again. If communication is normally performed via the predetermined path, the control unit105can continue the processing for relaying the information by successively acquiring information to be relayed, and transmitting the information via the predetermined path.

Note that, although the flow of the processing performed by the control unit105of the wireless relay device10has been described in this embodiment, there is no limitation thereto. The respective control units203of the plurality of wired relay devices20can also perform similar processing to that of the control unit105of the wireless relay device10and thus can achieve the redundancy of communication in the in-vehicle network4.

The embodiments that were disclosed here are to be considered in all aspects to be illustrative and not restrictive. The scope of the present disclosure is defined by the claims and not by the above description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.