Patent Publication Number: US-11639144-B2

Title: In-vehicle network system

Description:
INCORPORATION BY REFERENCE 
     This application is a Continuation of U.S. patent application Ser. No. 16/862,627 filed on Apr. 30, 2020, which claims the benefit of Japanese Patent Application No. 2019-127626 filed on Jul. 9, 2019, all of which are hereby incorporated by reference in their 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 to  FIGS.  3 A and  3 B . In the example shown in  FIG.  3 A , power from a power supply  900  is supplied to an ECU  902  as 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 lines  905 ,  906 , and  907 , respectively. The power line  905  directly connects the power supply  900  and the ECU  902 , and power is constantly supplied by the power line  905 . The power line  906  connects the power supply  900  and the ECU  902  via an ACC relay  903 . The power line  907  connects the power supply  900  and the ECU  902  via an IG relay  904 . A power supply management ECU  901  detects a user&#39;s operation of turning on an ACC or an IG using a key or a push switch, and operates the ACC relay  903  via a control line  908  and the IG relay  904  via a control line  909  in accordance with the detected operation. For example, when detecting the ACC ON operation, the power supply management ECU  901  closes the ACC relay  903  to supply power via the power line  906 . Further, when detecting the IG ON operation, the power supply management ECU  901  closes the IG relay  904  to supply power via the power line  907 . 
     The ECU  902  performs 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 lines  905 ,  906 , and  907 . For example, when the ACC power of the ACC power supply is supplied, the ECU  902  executes 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 ECU  902  executes a predetermined operation determined as the operation for an IG ON state. A communication line  910  connects the power supply management ECU  901  and the ECU  902 , and the power supply management ECU  901  and the ECU  902  can 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 ECU  902 . 
     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 in  FIG.  3 A . 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 in  FIG.  3 B , an ECU  912  includes an NM unit  913  that has the NM function, and power from the power supply  900  is supplied to the ECU  912  only as the +B power of the +B power supply via the power line  905 . A power supply management ECU  911  detects a user&#39;s operation of turning on the ACC or the IG using a key or a push switch, and instructs the ECU  912  via the communication line  910  in accordance with the detected operation. 
     In the standby state, the NM unit  913  waits for the above-described instruction from the power supply management ECU  911 , and upon receiving the instruction, shifts the ECU  912  to 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 ECU  912  further 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 ECU  912 , when the NM unit  913  determines that the ECU  912  may transition to the standby state based on the operation state of the ECU  912  and communication with the power supply management ECU  911  or the like, the NM unit  913  can cause the ECU  912  to transition to the standby state. 
     In the example shown in  FIG.  3 B , the number of power lines, relays, or the like can be reduced, and therefore costs can be reduced, as compared with the example shown in  FIG.  3 A . 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG.  1    is a diagram showing a configuration of a network system according to an embodiment of the disclosure; 
         FIG.  2    is a flowchart showing a startup process in the network system according to the embodiment of the disclosure; 
         FIG.  3 A  is a diagram showing power supply control of an ECU according to the related art; and 
         FIG.  3 B  is another diagram showing power supply control of an ECU according to the related art. 
     
    
    
     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.  1    is a diagram showing a configuration of a network system  1  according to the embodiment. 
     The network system  1  includes a tree-type connection topology.  FIG.  1    shows 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. In  FIG.  1   , an upper ECU  11  is the upper node. A first intermediate ECU  21  and a second intermediate ECU  22  are the intermediate nodes. First lower ECUs  31  are the lower nodes subordinate to the first intermediate ECU  21 , and second lower ECUs  32  are the lower nodes subordinate to the second intermediate ECU  22 . The network system  1  is mounted on a vehicle and includes the ECUs described above and a power supply  10  that supplies power to the ECUs. In the following description, as the intermediate nodes, two ECUs, namely, the first intermediate ECU  21  and the second intermediate ECU  22 , 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 ECU  11  is a relatively highly functional ECU that collectively performs computations for various vehicle control functions. The lower ECUs such as the first lower ECUs  31  and the second lower ECUs  32  are, 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 ECU  21  and the second intermediate ECU  22  are ECUs that function as gateways that relay communication between the upper ECU  11  and the lower ECUs. The first intermediate ECU  21  relays communication between the upper ECU  11  and the first lower ECUs  31 . The second intermediate ECU  22  relays communication between the upper ECU  11  and the second lower ECUs  32 . These ECUs are typically configured to include a control unit such as a processor or a microcomputer and a memory. 
     The upper ECU  11  and the first intermediate ECU  21  are connected by a communication line  111 . The first intermediate ECU  21  and the first lower ECUs  31  are connected by a communication line (bus)  211 . The upper ECU  11  and the second intermediate ECU  22  are connected by a communication line  112 . The second intermediate ECU  22  and the second lower ECUs  32  are connected by a communication line (bus)  212 . Communication between the upper ECU  11  and the first intermediate ECU  21  and communication between the upper ECU  11  and the second intermediate ECU  22  are performed in accordance with, for example, the Ethernet (registered trademark) standard. However, the communication standard is not limited thereto. Communication between the first intermediate ECU  21  and the first lower ECUs  31  and communication between the second intermediate ECU  22  and the second lower ECUs  32  are performed in accordance with, for example, the controller area network (CAN; registered trademark) standard. However, the communication standard is not limited thereto. 
     The power supply  10  is connected to the first intermediate ECU  21  and the second intermediate ECU  22  by a power line  101 . The first intermediate ECU  21  and the first lower ECUs  31  are connected by a power line  201 . Further, the second intermediate ECU  22  and the second lower ECUs  32  are connected by a power line  202 . Each of the first intermediate ECU  21  and the second intermediate ECU  22  includes a relay  28 . The relay  28  of the first intermediate ECU  21  can switch between a disconnected state and a connected state of the power line  101  and the power line  201 . The relay  28  of the second intermediate ECU  22  can switch between a disconnected state and a connected state of the power line  101  and the power line  202 . Although not shown, the power supply  10  and the upper ECU  11  may be connected by the power line  101 , or may be connected by another power line provided separately from the power lines described above. 
     Each of the first intermediate ECU  21  and the second intermediate ECU  22  includes an NM unit  29 . Each of the first lower ECUs  31  and the second lower ECUs  32  includes an NM unit  39 . The NM units  29  and  39  have 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 ECU  11  collects, for example, information on the vehicle and surrounding conditions of the vehicle from the first lower ECUs  31  and the second lower ECUs  32  that 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 ECU  11  performs 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 ECU  11  transmits the control data as appropriate to the first lower ECUs  31  and the second lower ECUs  32  that control the actuators to cause the actuators to operate in accordance with the control data. In the network system  1 , cost is reduced by concentrating various control functions of the vehicle in the upper ECU  11  and relatively simplifying the configurations of the first lower ECUs  31  and the second lower ECUs  32  instead. 
     Processes 
     A startup process of the network system  1  according to the embodiment will be described below.  FIG.  2    is a flowchart showing the startup process. As an example, a description will be given with reference to  FIG.  2    of a process in which, of the lower nodes, the three first lower ECUs  31  subordinate to the first intermediate ECU  21  are started as one target startup group. At the start of this process, the first intermediate ECU  21  is in the standby state as an initial state. The relay  28  of the first intermediate ECU  21  is opened such that the power line  101  and the power line  201  are not connected, and the first lower ECUs  31  are in a power-off state. 
     Step S 101   
     When determining that it is necessary to start the first lower ECUs  31 , the upper ECU  11  transmits a message to the first intermediate ECU  21  via the communication line  111 . 
     The upper ECU  11  can determine whether it is necessary to start the first lower ECUs  31  and what operation is to be performed by the first lower ECUs  31  when the first lower ECUs  31  are 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 ECUs  31 , operation requirements of the entire vehicle, or the like. For example, when the upper ECU  11  receives, 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 ECU  11  can determine that it is necessary to cause the first lower ECUs  31  to 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 ECUs  31  such as IG ON. The operation of the first lower ECUs  31  is 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. 
     Step S 102   
     The first intermediate ECU  21  receives the message. The NM unit  29  causes the first intermediate ECU  21  to transition from the standby state to the startup state in accordance with the instruction in the message to transition to the startup state. 
     Step S 103   
     The first intermediate ECU  21  closes the relay  28  to connect the power line  101  and the power line  201 , and starts power supply from the power supply  10  to the first lower ECUs  31  via the first intermediate ECU  21 . 
     Step S 104   
     When power is supplied to the first lower ECUs  31 , the NM units  39  cause the first lower ECUs  31  to transition to the standby state as the initial state. 
     Step S 105   
     The first intermediate ECU  21  converts a format of the message transmitted from the upper ECU  11  as appropriate in accordance with a difference in the communication standard, and relays the message to the first lower ECUs  31  in the standby state. Note that the first intermediate ECU  21  can appropriately detect that the first lower ECUs  31  have transitioned to the standby state, for example, through communication with the first lower ECU  31   s.    
     Step S 106   
     The first lower ECUs  31  receive the message. The NM units  39  cause the first lower ECUs  31  to 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 ECUs  31  specify and execute the operation based on the information included in the message and specifying the operation such as IG ON. 
     Step S 107   
     Communication for controlling various functions of the vehicle is started. The first intermediate ECU  21  relays communication between the upper ECU  11  and the first lower ECUs  31 . The first lower ECUs  31  also communicate with each other. Thus, the startup process of the first lower ECU  31   s  ends. After that, when the upper ECU  11  determines that the first lower ECUs  31  do not need to be operated, for example, by detecting that the user has performed an operation such as IG OFF, the upper ECU  11  causes the first lower ECUs  31  to transition to the standby state, causes the relay  28  of the first intermediate ECU  21  to open to stop power supply, and causes the first intermediate ECU  21  to transition to the standby state, conforming to the NM function. 
     In the above description, the instruction to cause the first intermediate ECU  21  and the first lower ECUs  31  to transition to the startup state and the information used to specify the operation of the first lower ECUs  31  such 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 ECU  11 . 
     Modification 
     In the network system  1  described above, the upper ECU  11  and the first intermediate ECU  21  are connected by the communication line  111 , and the upper ECU  11  and the second intermediate ECU  22  are connected by the communication line  112  that is different from the communication line  111 . 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 ECU  11  is connected to the first intermediate ECU  21  and the second intermediate ECU  22  by a bus, the messages transmitted from the upper ECU  11  to the first intermediate ECU  21  include a message for starting the first lower ECUs  31  subordinate to the first intermediate ECU  21  and a message for starting the second lower ECUs  32  subordinate to the second intermediate ECU  22 . In step S 102 , the first intermediate ECU  21  transitions from the standby state to the startup state in accordance with the standard of the NM function, regardless of the message received. 
     In step S 102 , the first intermediate ECU  21  that has transitioned to the startup state determines whether it is necessary to start the subordinate first lower ECUs  31  based on the received message. This determination can be made when the upper ECU  11  transmits the message including information necessary for the determination, and the first intermediate ECU  21  refers 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 ECUs  31 . 
     When the first intermediate ECU  21  determines that the first lower ECUs  31  need to be started, the process proceeds to step  5103 . When the first intermediate ECU  21  determines that the first lower ECUs  31  do not need to be started, the first intermediate ECU  21  waits to receive the next message from the upper ECU  11 . Thereafter, when the first intermediate ECU  21  determines that the first lower ECUs  31  need to be started based on the next message received, the process proceeds to step  5103 , and when the first intermediate ECU  21  determines that the first lower ECUs  31  do not need to be started based on the next message received, the first intermediate ECU  21  repeats the process of waiting to receive the next message. 
     In the embodiment and modification, the process when the first lower ECUs  31  subordinate to the first intermediate ECU  21  are started has been described as an example. A similar process may be performed when the second lower ECUs  32  subordinate to the second intermediate ECU  22  are started. 
     Effect 
     The network system  1  according 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.