In-vehicle network system

An in-vehicle network system includes a power supply, an upper electronic control unit (ECU), an intermediate ECU configured to communicate with the upper ECU, and a plurality of lower ECUs configured to communicate with the intermediate ECU. The intermediate ECU is configured to receive power supplied from the power supply, and maintain the lower ECUs in a power-off state until the intermediate ECU receives a message from the upper ECU and supply the power supplied from the power supply to the lower ECUs in response to the message transmitted from the upper ECU. The lower ECUs are configured to transition, when the power is supplied from the power supply, from the power-off state to a standby state to wait for an instruction.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2019-127626 filed on Jul. 9, 2019 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The disclosure relates to an in-vehicle network system.

2. Description of Related Art

A vehicle is equipped with a plurality of in-vehicle devices each called an electronic control unit (ECU). One mode of operation control of the ECUs will be described with reference toFIGS. 3A and 3B. In the example shown inFIG. 3A, power from a power supply900is supplied to an ECU902as battery (+B) power of a +B power supply, accessory (ACC) power of an ACC power supply, and ignition (IG) power of an IG power supply via three power lines905,906, and907, respectively. The power line905directly connects the power supply900and the ECU902, and power is constantly supplied by the power line905. The power line906connects the power supply900and the ECU902via an ACC relay903. The power line907connects the power supply900and the ECU902via an IG relay904. A power supply management ECU901detects a user's operation of turning on an ACC or an IG using a key or a push switch, and operates the ACC relay903via a control line908and the IG relay904via a control line909in accordance with the detected operation. For example, when detecting the ACC ON operation, the power supply management ECU901closes the ACC relay903to supply power via the power line906. Further, when detecting the IG ON operation, the power supply management ECU901closes the IG relay904to supply power via the power line907.

The ECU902performs an operation in accordance with a combination of whether the +B power of the +B power supply, the ACC power of the ACC power supply, and the IG power of the IG power supply are supplied via the three power lines905,906, and907. For example, when the ACC power of the ACC power supply is supplied, the ECU902executes a predetermined operation determined as the operation for an ACC ON state, and when the IG power of the IG power supply is supplied, the ECU902executes a predetermined operation determined as the operation for an IG ON state. A communication line910connects the power supply management ECU901and the ECU902, and the power supply management ECU901and the ECU902can communicate with each other. One or two of the +B power supply, the ACC power supply, and the IG power supply may be omitted depending on the specifications of the ECU902.

As another mode of the operation control of the ECU, a mode has been proposed in which a function called a network management (NM) function is added to the ECU to reduce the number of power lines compared to the mode shown inFIG. 3A. The NM function includes a function that enables control on a bus basis to switch the state of each ECU connected to a communication bus between a standby state in which operation is suppressed and a startup state in which operation can be executed (Japanese Unexamined Patent Application Publication No. 2016-134855 (JP 2016-134855 A)). In the example illustrated inFIG. 3B, an ECU912includes an NM unit913that has the NM function, and power from the power supply900is supplied to the ECU912only as the +B power of the +B power supply via the power line905. A power supply management ECU911detects a user's operation of turning on the ACC or the IG using a key or a push switch, and instructs the ECU912via the communication line910in accordance with the detected operation.

In the standby state, the NM unit913waits for the above-described instruction from the power supply management ECU911, and upon receiving the instruction, shifts the ECU912to the startup state. This instruction is a message in a format conforming to the specification of the NM function, and the message can include, for example, information such as ACC ON and IG ON. After transitioning to the startup state, the ECU912further executes the predetermined operations for the ACC ON state or the IG ON state based on the information included in the instruction. In the startup state of the ECU912, when the NM unit913determines that the ECU912may transition to the standby state based on the operation state of the ECU912and communication with the power supply management ECU911or the like, the NM unit913can cause the ECU912to transition to the standby state.

In the example shown inFIG. 3B, the number of power lines, relays, or the like can be reduced, and therefore costs can be reduced, as compared with the example shown inFIG. 3A.

SUMMARY

Since the ECU including the NM function consumes standby power even in the standby state in which the ECU does not need to operate, the standby power increases in a network system that includes a large number of ECUs.

The disclosure provides an in-vehicle network system in which standby power is suppressed.

The in-vehicle network system according to a first aspect of the disclosure includes a power supply, an upper ECU, an intermediate ECU configured to communicate with the upper ECU, and a plurality of lower ECUs configured to communicate with the intermediate ECU. The intermediate ECU is configured to receive power supplied from the power supply, and maintain the lower ECUs in a power-off state until the intermediate ECU receives a message from the upper ECU and supply the power supplied from the power supply to the lower ECUs in response to the message transmitted from the upper ECU. The lower ECUs are configured to transition, when the power is supplied from the power supply, from the power-off state to a standby state to wait for an instruction.

According to the first aspect of the disclosure, the intermediate ECU may be further configured to transmit a message to the lower ECUs in the standby state in response to the message transmitted from the upper ECU. The lower ECUs may be configured to transition from the standby state to a startup state in response to the message transmitted from the intermediate ECU.

According to the first aspect of the disclosure, the lower ECUs may be configured to specify an operation in the startup state in response to the message transmitted from the intermediate ECU.

According to the disclosure, the ECU is set to the power-off state instead of the standby state in which the standby power is consumed, so that it is possible to provide an in-vehicle network system in which the standby power is suppressed.

DETAILED DESCRIPTION OF EMBODIMENTS

A network system according to the disclosure employs an NM function to reduce the number of power lines or the like. In the network system, an ECU that does not need to be currently started is set to a power-off state in which no power is consumed, instead of a standby state of the NM function in which standby power is consumed, and when the need for starting the ECU occurs, power is supplied to set a startup state after the standby state. Thereby, the standby power of the network system can be suppressed.

EMBODIMENT

Hereinafter, an embodiment of the disclosure will be described in detail with reference to the drawings.

Configuration

FIG. 1is a diagram showing a configuration of a network system1according to the embodiment.

The network system1includes a tree-type connection topology.FIG. 1shows a configuration in which two intermediate nodes are subordinate to one upper node, and three lower nodes are subordinate to each of the intermediate nodes. InFIG. 1, an upper ECU11is the upper node. A first intermediate ECU21and a second intermediate ECU22are the intermediate nodes. First lower ECUs31are the lower nodes subordinate to the first intermediate ECU21, and second lower ECUs32are the lower nodes subordinate to the second intermediate ECU22. The network system1is mounted on a vehicle and includes the ECUs described above and a power supply10that supplies power to the ECUs. In the following description, as the intermediate nodes, two ECUs, namely, the first intermediate ECU21and the second intermediate ECU22, are provided. However, the number of the intermediate nodes and the number of the lower nodes subordinate to each of the intermediate nodes are not specifically limited. That is, two ECUs are provided as the intermediate nodes in this embodiment, but an ECU may be provided as the intermediate node, and three or more ECUs may be provided as the intermediate node. Furthermore, three ECUs are provided as the lower nodes subordinate to each of the intermediate nodes in this embodiment, but two or less ECUs may be provided as the lower nodes, and four or more ECUs may be provided as the lower nodes.

As an example, the upper ECU11is a relatively highly functional ECU that collectively performs computations for various vehicle control functions. The lower ECUs such as the first lower ECUs31and the second lower ECUs32are, for example, ECUs provided in each component of the vehicle and having relatively specialized functions for individually controlling each sensor or each actuator. The intermediate ECUs such as the first intermediate ECU21and the second intermediate ECU22are ECUs that function as gateways that relay communication between the upper ECU11and the lower ECUs. The first intermediate ECU21relays communication between the upper ECU11and the first lower ECUs31. The second intermediate ECU22relays communication between the upper ECU11and the second lower ECUs32. These ECUs are typically configured to include a control unit such as a processor or a microcomputer and a memory.

The upper ECU11and the first intermediate ECU21are connected by a communication line111. The first intermediate ECU21and the first lower ECUs31are connected by a communication line (bus)211. The upper ECU11and the second intermediate ECU22are connected by a communication line112. The second intermediate ECU22and the second lower ECUs32are connected by a communication line (bus)212. Communication between the upper ECU11and the first intermediate ECU21and communication between the upper ECU11and the second intermediate ECU22are performed in accordance with, for example, the Ethernet (registered trademark) standard. However, the communication standard is not limited thereto. Communication between the first intermediate ECU21and the first lower ECUs31and communication between the second intermediate ECU22and the second lower ECUs32are performed in accordance with, for example, the controller area network (CAN; registered trademark) standard. However, the communication standard is not limited thereto.

The power supply10is connected to the first intermediate ECU21and the second intermediate ECU22by a power line101. The first intermediate ECU21and the first lower ECUs31are connected by a power line201. Further, the second intermediate ECU22and the second lower ECUs32are connected by a power line202. Each of the first intermediate ECU21and the second intermediate ECU22includes a relay28. The relay28of the first intermediate ECU21can switch between a disconnected state and a connected state of the power line101and the power line201. The relay28of the second intermediate ECU22can switch between a disconnected state and a connected state of the power line101and the power line202. Although not shown, the power supply10and the upper ECU11may be connected by the power line101, or may be connected by another power line provided separately from the power lines described above.

Each of the first intermediate ECU21and the second intermediate ECU22includes an NM unit29. Each of the first lower ECUs31and the second lower ECUs32includes an NM unit39. The NM units29and39have the network management (NM) function described above, and perform control to switch the state of each ECU between the standby state in which operation is suppressed and the startup state in which various operations can be executed.

The upper ECU11collects, for example, information on the vehicle and surrounding conditions of the vehicle from the first lower ECUs31and the second lower ECUs32that control the sensors. This information may include, for example, operational conditions of the actuators, etc., driving conditions of the vehicle such as vehicle speed and acceleration, environmental conditions of the vehicle such as roads and objects surrounding the vehicle, a seating status of an occupant, and details of operations performed with respect to each component of the vehicle. The upper ECU11performs computations based on this information and generates control data. The control data is data for controlling various functions of the vehicle, such as an autonomous driving function, a self-parking function, drive assistance functions including collision avoidance, lane keeping, automatic follow-up of the preceding vehicle, and cruise control, operational control of an engine, a transmission, a cooling device, and an air conditioner, charging and discharging control of a battery, lighting of headlamps in accordance with illuminance, permission of unlocking doors based on authentication using a mobile device (electronic key), and presentation of information to a user. The upper ECU11transmits the control data as appropriate to the first lower ECUs31and the second lower ECUs32that control the actuators to cause the actuators to operate in accordance with the control data. In the network system1, cost is reduced by concentrating various control functions of the vehicle in the upper ECU11and relatively simplifying the configurations of the first lower ECUs31and the second lower ECUs32instead.

Processes

A startup process of the network system1according to the embodiment will be described below.FIG. 2is a flowchart showing the startup process. As an example, a description will be given with reference toFIG. 2of a process in which, of the lower nodes, the three first lower ECUs31subordinate to the first intermediate ECU21are started as one target startup group. At the start of this process, the first intermediate ECU21is in the standby state as an initial state. The relay28of the first intermediate ECU21is opened such that the power line101and the power line201are not connected, and the first lower ECUs31are in a power-off state.

When determining that it is necessary to start the first lower ECUs31, the upper ECU11transmits a message to the first intermediate ECU21via the communication line111.

The upper ECU11can determine whether it is necessary to start the first lower ECUs31and what operation is to be performed by the first lower ECUs31when the first lower ECUs31are started, based on, for example, information received from another ECU that has already been started. A specific method of such determination is determined in accordance with operation specifications of the first lower ECUs31, operation requirements of the entire vehicle, or the like. For example, when the upper ECU11receives, from the ECU that controls a push switch, information indicating that the user has pressed the push switch to perform an operation of instructing the power supply of the vehicle to switch from the OFF state to the IG ON state, the upper ECU11can determine that it is necessary to cause the first lower ECUs31to perform the operation for the IG ON state. The message includes an instruction to cause the subordinate nodes to transition to the startup state, and information used to specify the operation of the first lower ECUs31such as IG ON. The operation of the first lower ECUs31is not defined by only the conventional power supply state such as ACC ON and IG ON, but can be variously defined in accordance with advanced functions of the vehicle and the ECU.

The first intermediate ECU21receives the message. The NM unit29causes the first intermediate ECU21to transition from the standby state to the startup state in accordance with the instruction in the message to transition to the startup state.

The first intermediate ECU21closes the relay28to connect the power line101and the power line201, and starts power supply from the power supply10to the first lower ECUs31via the first intermediate ECU21.

When power is supplied to the first lower ECUs31, the NM units39cause the first lower ECUs31to transition to the standby state as the initial state.

The first intermediate ECU21converts a format of the message transmitted from the upper ECU11as appropriate in accordance with a difference in the communication standard, and relays the message to the first lower ECUs31in the standby state. Note that the first intermediate ECU21can appropriately detect that the first lower ECUs31have transitioned to the standby state, for example, through communication with the first lower ECU31s.

The first lower ECUs31receive the message. The NM units39cause the first lower ECUs31to transition from the standby state to the startup state in accordance with the instruction in the message to transition to the startup state. The first lower ECUs31specify and execute the operation based on the information included in the message and specifying the operation such as IG ON.

Communication for controlling various functions of the vehicle is started. The first intermediate ECU21relays communication between the upper ECU11and the first lower ECUs31. The first lower ECUs31also communicate with each other. Thus, the startup process of the first lower ECU31sends. After that, when the upper ECU11determines that the first lower ECUs31do not need to be operated, for example, by detecting that the user has performed an operation such as IG OFF, the upper ECU11causes the first lower ECUs31to transition to the standby state, causes the relay28of the first intermediate ECU21to open to stop power supply, and causes the first intermediate ECU21to transition to the standby state, conforming to the NM function.

In the above description, the instruction to cause the first intermediate ECU21and the first lower ECUs31to transition to the startup state and the information used to specify the operation of the first lower ECUs31such as IG ON are included in the same message. However, the above configuration is not limited as long as a similar startup process can be executed. For example, these instructions and information may be individually included in two messages separately transmitted from the upper ECU11.

Modification

In the network system1described above, the upper ECU11and the first intermediate ECU21are connected by the communication line111, and the upper ECU11and the second intermediate ECU22are connected by the communication line112that is different from the communication line111. That is, the upper node and each intermediate node are not connected by a one-to-many bus connection, but are connected by a one-to-one connection with a dedicated line. This is because, in order for the upper node to communicate with many lower nodes connected by each intermediate node without interruption, providing a dedicated line between the upper node and the intermediate node can facilitate a design that guarantees a sufficient band rather than bus connection. However, as a modification, a mode in which the upper node and each intermediate node are connected by a one-to-many bus connection may be adopted. In this case, a part of the process described above is changed. The changes to be made will be described below.

In the mode in which the upper ECU11is connected to the first intermediate ECU21and the second intermediate ECU22by a bus, the messages transmitted from the upper ECU11to the first intermediate ECU21include a message for starting the first lower ECUs31subordinate to the first intermediate ECU21and a message for starting the second lower ECUs32subordinate to the second intermediate ECU22. In step S102, the first intermediate ECU21transitions from the standby state to the startup state in accordance with the standard of the NM function, regardless of the message received.

In step S102, the first intermediate ECU21that has transitioned to the startup state determines whether it is necessary to start the subordinate first lower ECUs31based on the received message. This determination can be made when the upper ECU11transmits the message including information necessary for the determination, and the first intermediate ECU21refers to this information. This information may be information such as the IG ON described above, or may be information that more specifically specifies the first lower ECUs31.

When the first intermediate ECU21determines that the first lower ECUs31need to be started, the process proceeds to step S103. When the first intermediate ECU21determines that the first lower ECUs31do not need to be started, the first intermediate ECU21waits to receive the next message from the upper ECU11. Thereafter, when the first intermediate ECU21determines that the first lower ECUs31need to be started based on the next message received, the process proceeds to step S103, and when the first intermediate ECU21determines that the first lower ECUs31do not need to be started based on the next message received, the first intermediate ECU21repeats the process of waiting to receive the next message.

In the embodiment and modification, the process when the first lower ECUs31subordinate to the first intermediate ECU21are started has been described as an example. A similar process may be performed when the second lower ECUs32subordinate to the second intermediate ECU22are started.

Effect

The network system1according to the embodiment and the modification employs the NM function to reduce the number of power lines or the like, and the lower ECUs that do not need to be currently started are set to the power-off state in which no power is consumed, instead of the standby state of the NM function in which the standby power is consumed. When the need for starting the lower ECUs occurs, power is supplied to set the startup state after the standby state. This suppresses the standby power even when the number of the lower ECUs is large. Also, by grouping the lower ECUs under a plurality of the intermediate ECUs, starting can be instructed in groups, so that only the lower ECUs in the group that need to be started can be started, and the power-off state of the other lower ECUs can be maintained without being started in conjunction with the group started above. Thus, power consumption can be suppressed.

The ECUs do not need to include the NM function, and the lower ECUs may be started when the intermediate ECU starts power supply to the lower ECUs in response to an instruction from the upper ECU. Also in this case, the effect of suppressing power consumption by the startup control in groups described above can be obtained.

The disclosure is not limited to the network system, and can be implemented as a method of controlling the network system, a control program for the network system to be performed by the ECU having a processor and a memory and a computer-readable non-transitory storage medium that stores the control program, and a vehicle equipped with the network system, etc. In addition, the disclosure can be applied to network systems other than the network system mounted on the vehicle.

The disclosure is advantageous for a network system mounted on a vehicle or the like.