JP7724054B2 - Communication systems and electronic control devices - Google Patents

Description

The present invention relates to a communication system and an electronic control device.

Vehicles such as automobiles are equipped with communication systems that connect numerous electronic control units (ECUs). CAN (Control Area Network), for example, is a well-known communication protocol that is widely used in in-vehicle networks.

The amount of information transmitted over in-vehicle networks is increasing due to factors such as the increase in ECUs and the introduction of autonomous driving. As a result, existing standards are being expanded and faster Ethernet (registered trademark) is being used for in-vehicle networks.

Japanese Patent Application Laid-Open No. 2017-118407

Patent Document 1 connects a high-speed Ethernet to an in-vehicle network, acquires data blocks from high-speed frames received from the Ethernet, and transmits the data blocks to a low-speed communication line in the in-vehicle network. Although Patent Document 1 connects a high-speed Ethernet, it does not speed up the entire in-vehicle network.

In Ethernet communications, virtual local area networks (VLANs) are used to virtually divide the network into domains, separating traffic and reducing the amount of traffic flowing across the entire network, thereby increasing speed. Typically, VLANs are configured based on switch ports, and Ethernet frames are only forwarded to ports on the same VLAN.

Within the same VLAN, Ethernet frames can be transferred at Layer 2 (data link layer), but communication between VLANs requires data transfer at the higher layer, Layer 3 (network layer). Data transfer at higher layers increases the processing load and data delays, so relay devices require more powerful CPUs.

When applying a general Ethernet communication system to an in-vehicle communication system, it is conceivable to configure VLANs based on the physical domain to which the ECU belongs, such as the infotainment system, cluster system, or Intelligent Transport Systems (ITS) system. However, in-vehicle networks often involve communication between domains, and when there is a lot of traffic between VLANs, there is a risk of delays in data transfer, making it necessary to install high-performance CPUs in ECUs such as central gateways that connect multiple ECUs.

The present invention was made in consideration of the above, and aims to provide a faster in-vehicle network.

A communication system according to one aspect of the present invention is an in-vehicle communication system that includes multiple electronic control units connected to each other so that they can communicate with each other. In this communication system, an identifier for determining the data path is assigned to each function. Each electronic control unit stores the identifiers assigned to each of its multiple functions, and transmits data with an identifier corresponding to the data to be transmitted.

The present invention makes it possible to provide a faster in-vehicle network.

FIG. 1 is a diagram illustrating the overall configuration of a communication system according to this embodiment. FIG. 2 is a functional block diagram showing an example of the configuration of the electronic control unit. FIG. 3 is a diagram showing an example of a table that associates functions held by an electronic control unit with VIDs. FIG. 4 is a functional block diagram illustrating an example of the configuration of a gateway. FIG. 5 is a diagram showing an example of a table in which port numbers and VIDs are associated with each other and stored in the gateway. FIG. 6 is a flowchart showing an example of a process flow in which the electronic control unit transmits data. FIG. 7 is a flowchart showing an example of the flow of a process in which the gateway transfers data. FIG. 8 is a diagram showing an example in which the layout of the electronic control unit is changed.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, identical parts will be designated by the same reference numerals and their descriptions will be omitted.

The communication system of this embodiment will be described with reference to Figure 1. The communication system shown in Figure 1 is an in-vehicle communication system and includes electronic control units (ECUs) 1A-1F and a gateway (GW) 2. ECUs 1A-1F and GW2 are connected by communication lines. ECUs 1A and 1B are in-vehicle ECUs that belong to the chassis domain, ECU 1C is the engine domain, and ECUs 1D, 1E, and 1F are ITS domain ECUs. Each of ECUs 1A-1F has the function of electronically controlling the systems of its respective domain. GW2 has multiple connection ports for connecting communication lines and has the function of relaying data sent and received between ECUs 1A-1F. GW2 is also a type of ECU. Like ECU 1D, an ECU may have multiple connection ports to relay data. Note that Figure 1 is an example for explaining the communication system, and while it illustrates six ECUs and only one GW, this is not limiting.

ECUs 1A-1F and GW2 communicate by sending and receiving Ethernet frames with VLAN tags. The VLAN tag contains a VLAN Identifier (VID) and a Priority Code Point (PCP) and is added to the header of the Ethernet frame. The VID is an identifier that specifies the VLAN. The PCP is a field that specifies the priority. The VLAN tag also contains other information, but this will not be explained here.

In the communication system of this embodiment, logical groups are formed based on function rather than on domains, and each ECU belongs to one or more logical groups according to its functions. A logical group is also called a VLAN. ECUs with multiple functions are assigned multiple IP addresses for each function, and a corresponding VID is assigned to each IP address. For example, in the example shown in Figure 1, VID = 100 is assigned to diagnostic functions, VID = 400 to control functions, VID = 800 to human-machine interface (HMI) functions, and VID = 930 to special control applications, forming logical groups by VID. ECUs 1A, 1B, 1C, 1D, and GW2 belong to the diagnostic group. ECUs 1D, 1E, and 1F belong to the control group. ECUs 1A and 1C belong to the HMI group. ECUs 1D and 1F belong to the special control application group. ECUs 1A, 1C, 1D, and 1F belong to multiple logical groups.

In the communication system of this embodiment, a VID may be assigned to each type of data and a VLAN may be formed for each data type, or a VID may be assigned to each application that uses the data and a VLAN may be formed for each application. When forming VLANs, a VLAN may be formed for each function, and then VLANs may be formed for each data type and application. Functions are classified at a relatively large level, such as images, sensors, and diagnostics. Data types and applications are classified at a smaller level, such as images taken by a camera or images used in a navigation system, among image-related functions. By forming VLANs at a smaller level, the broadcast range is narrowed, and the amount of traffic flowing throughout the communication system can be reduced.

GW2 is equipped with a forwarding unit 21 with multiple connection ports and connects multiple ECUs. GW2 determines the data path based on the VLAN tag attached to the Ethernet frame and forwards the Ethernet frame at Layer 2. Even if data is exchanged between different domains, such as between ECU 1A and ECU 1C in Figure 1, ECU 1A and ECU 1C belong to the same logical group (VID = 100 or VID = 800), so GW2 forwards data between ECU 1A and ECU 1C at Layer 2 according to the VLAN tag. Note that ECU 1D, which is equipped with a forwarding unit 21 with multiple connection ports, also forwards data exchanged between ECUs at Layer 2 according to the VLAN tag, just like GW2.

Next, the configuration of ECU 1 will be explained with reference to Figure 2. When there is no need to distinguish between ECUs 1A to 1F, they will be referred to as ECU 1.

The ECU 1 shown in Figure 2 includes a communication unit 11, a control unit 12, and a memory unit 13.

The communication unit 11 has a connection port for connecting a communication line, and transmits data by assigning a VLAN tag corresponding to the data to be transmitted, and receives data from other ECUs 1 or GWs 2. The communication unit 11 may have multiple connection ports to connect to multiple ECUs 1 and GWs 2. The communication unit 11 sets the IP address assigned to the ECU 1 as the source IP address in the IP header, and assigns a VLAN tag including the VID assigned to that IP address to the Ethernet header. The communication unit 11 may also set a priority to the PCP in the VAL tag. If the ECU 1 has multiple IP addresses, the communication unit 11 sets an IP address corresponding to the data in the IP header, and assigns a VLAN tag including the VID assigned to that IP address to the Ethernet header. For example, ECU 1A in Figure 1 belongs to a diagnostic system group and an HMI system group. When ECU 1A transmits data related to diagnostic functions, communication unit 11 sets the IP address assigned VID=100 of the diagnostic group as the source IP address of the IP header, and adds a VLAN tag including VID=100 of the diagnostic group to the Ethernet header. When ECU 1A transmits data related to HMI functions, communication unit 11 sets the IP address assigned VID=800 of the HMI group as the source IP address of the IP header, and adds a VLAN tag including VID=800 of the HMI group to the Ethernet header.

The control unit 12 electronically controls the system of the domain to which the ECU 1 belongs. When electronically controlling the system, the control unit 12 sends and receives data to and from other ECUs 1.

The memory unit 13 stores a VID assigned to each function of the ECU 1. Figure 3 shows an example of a table held in the memory unit 13 of the ECU 1A. The ECU 1A has diagnostic functions and HMI functions, with VID=100 assigned to the diagnostic group and VID=800 assigned to the HMI group. The table may also include IP addresses corresponding to the functions. The communication unit 11 refers to the memory unit 13 and assigns VID=100 to data related to diagnostic functions and VID=800 to data related to HMI functions.

Next, we will explain the configuration of GW2 with reference to Figure 4.

The GW2 shown in Figure 4 includes a forwarding unit 21, a control unit 22, and a memory unit 23.

The forwarding unit 21 has multiple connection ports and is connected to multiple ECUs 1, and forwards Ethernet frames at Layer 2 based on the VLAN tag assigned to the Ethernet frames.

The control unit 22 controls the GW2 itself. If the GW2 has diagnostic functions, the control unit 22 performs the diagnosis and transmits data including the diagnosis results.

The memory unit 23 holds a table that associates VIDs with connection ports. Figure 5 shows an example of a table held by the memory unit 23 of GW2. GW2 is assumed to have connection ports numbered 1 to 5. In the table of Figure 5, each connection port is associated with a VID assigned to the connected ECU1. In the example of Figure 1, VIDs = 100 and 800 are assigned to ECU 1A and ECU 1C, VID = 100 is assigned to ECU 1B, and VIDs = 100, 400, and 930 are assigned to ECU 1D. Connection port 1 is connected to ECU 1A, connection port 2 is connected to ECU 1B, connection port 3 is connected to ECU 1C, and connection port 4 is connected to ECU 1D. Connection port 5 is connected to the control unit 22 of GW2 itself. The control unit 22 has diagnostic functions. Therefore, in the table in Figure 5, connection port 1 is associated with VID = 100,800, connection port 2 is associated with VID = 100, connection port 3 is associated with VID = 100,800, connection port 4 is associated with VID = 100,400,930, and connection port 5 is associated with VID = 100.

The transfer unit 21 refers to the table held in the memory unit 23 and sends the data from the connection port that corresponds to the VID assigned to the received data. For example, if data with VID=100 is received from connection port 1, the transfer unit 21 sends the data from connection ports 2 to 5.

The forwarding unit 21 may learn the MAC address of the sender, update the MAC address table, and determine the connection port from which to send the data based on the MAC address table. For example, when the forwarding unit 21 receives data (Ethernet frame) from a certain connection port, it updates the MAC address table by associating the source MAC address in the header of the received Ethernet frame with that connection port. When the forwarding unit 21 receives data, it refers to the MAC address table to identify the connection port associated with the MAC address of the destination of the received data, and sends the data from that connection port. A VID and a MAC address may also be associated with the connection port in the table in FIG. 5. Note that a MAC address registered in the MAC address table is deleted from the MAC address table if no Ethernet frame with that MAC address as its source is received for a predetermined period of time. If the destination MAC address is not registered in the MAC address table, the forwarding unit 21 determines the connection port from which to send the data based on the VID.

Each unit of ECU1 and GW2 may be configured as a computer equipped with an arithmetic processing unit, storage device, etc., and the processing of each unit may be executed by a program. This program is stored in the storage device of ECU1 and GW2, and can also be recorded on a recording medium such as a magnetic disk, optical disk, or semiconductor memory, or provided via a network.

Next, the process by which ECU 1 transmits data will be explained with reference to the flowchart in Figure 6.

In step S11, ECU1 sets the IP address of ECP1, the data destination, as the destination IP address in the IP header, and sets an IP address corresponding to the data as the source IP address in the IP header.

In step S12, ECU1 assigns a VLAN tag according to the data. For example, in the example of Figure 1, even if the communication is between the same ECU1A and ECU1C, if the data relates to a diagnostic function, a VLAN tag with VID=100 is assigned, and if the data relates to an HMI function, a VLAN tag with VID=800 is assigned. ECU1 may set a priority for the PCP of the VLAN tag.

In step S13, ECU1 sends the data with the VLAN tag attached from the connection port.

Data sent from ECU1 is transferred by GW2.

Next, we will explain the process by which GW2 transfers data, with reference to the flowchart in Figure 7.

In step S21, GW2 receives data from ECU1.

In step S22, GW2 sends the data based on the VLAN tag of the received data. GW2 may also send the data based on the destination MAC address. In either case, the data is transferred at Layer 2.

Next, we will explain how to change the ECU layout with reference to Figure 8.

In Figure 8, the connection ports through which ECU 1B and ECU 1C in Figure 1 connect to GW2 have been swapped. Specifically, the state in which ECU 1B was connected to connection port number 2 of GW2 and ECU 1C was connected to connection port number 3 has been changed to the state in which ECU 1C is connected to connection port number 2 and ECU 1B is connected to connection port number 3.

In the communication system of this embodiment, VIDs are not set based on physical connections such as connection ports, but are set based on function. Therefore, even if the connection port of ECU1 is changed, there is no need to change the settings of ECU1; only the settings of GW2 need to be changed. In the example of Figure 8, the association between connection ports 2 and 3 and VIDs in the table held by GW2 is changed. VID = 100,800 is associated with connection port 2, and VID = 100 is associated with connection port 3. Since data is basically transferred at Layer 2, there is no need to change the settings of ECU1B and ECU1C.

As described above, the communication system of this embodiment provides the following advantages:

A VID for determining the data path is assigned to each function of ECUs 1A-1F, and a VLAN is formed for each function. Each of ECUs 1A-1F has a storage unit 13 that stores the VIDs assigned to each of its multiple functions, and a communication unit 11 that assigns a VID corresponding to the data to be transmitted and transmits it. As a result, data is sent and received between ECUs 1A-1F within the VLANs divided by function, regardless of the domain to which ECUs 1A-1F belong, thereby improving data transfer performance. This brings various benefits to improving autonomous driving performance, which requires processing large amounts of data.

GW2 has multiple connection ports, maintains a table in which each connection port corresponds to one or more VIDs, and sends data from the connection port corresponding to the VID assigned to the data. This allows data with VIDs assigned to it to be transferred efficiently in the communications system.

1, 1A to 1F... Electronic control unit 11... Communication unit 12... Control unit 13... Storage unit 2... Gateway 21... Transfer unit 22... Control unit 23... Storage unit

Claims (8)

An in-vehicle communication system comprising a plurality of electronic control units connected to each other so as to be able to communicate with each other,
Each function is assigned an identifier to determine the data path.
The identifier is assigned to each type of data to be transmitted and each application that uses the data in addition to the function,
Each of the electronic control devices is
a storage unit that stores the identifiers assigned to each of a plurality of functions of the electronic control device;
a communication unit that assigns an identifier corresponding to the data to be transmitted and transmits the data;
A communication system comprising: 2. The communication system of claim 1,
Among the plurality of electronic control devices, the electronic control device having a relay function and including a plurality of connection ports for connecting the electronic control devices with communication lines holds a table in which one or more of the identifiers correspond to each of the connection ports, and transmits the data from the connection port corresponding to the identifier assigned to the data.
Communication system. An electronic control device constituting an in-vehicle communication system ,
Each function is assigned an identifier to determine the data path.
The identifier is assigned to each type of data to be transmitted and each application that uses the data in addition to the function ,
a storage unit that stores the identifiers assigned to each of a plurality of functions of the electronic control device;
A communication unit that assigns an identifier corresponding to the data to be transmitted and transmits the data.
Electronic control unit . 4. The electronic control device according to claim 3 ,
a plurality of connection ports for connecting the electronic control devices with communication lines ;
maintaining a table in which one or more of the identifiers are associated with each of the connection ports;
The communication unit transmits the data from the connection port corresponding to the identifier assigned to the data.
Electronic control unit . 2. The communication system of claim 1 ,
Among the plurality of electronic control devices, an electronic control device having a relay function and including a plurality of connection ports for connecting the electronic control devices with communication lines refers to a MAC address table in which the MAC address of the electronic control device that is the sender of past data received in the past is associated with the connection port that received the past data, identifies the connection port associated with the MAC address of the destination of newly received new data, and transmits the new data from the identified connection port.
Communication system . 4. The electronic control device according to claim 3 ,
Among the plurality of electronic control devices, an electronic control device having a relay function and including a plurality of connection ports for connecting the electronic control devices with communication lines refers to a MAC address table in which the MAC address of the electronic control device that is the sender of past data received in the past is associated with the connection port that received the past data, identifies the connection port associated with the MAC address of the destination of newly received new data, and transmits the new data from the identified connection port.
Electronic control unit. 6. A communication system according to claim 1 or 5 ,
A MAC address table is updated in which the MAC address of the electronic control device that is the sender of the past data received in the past is associated with the connection port that is a connection port for connecting the electronic control devices via a communication line and that received the past data, to associate the past data received within a predetermined time from the present, and the connection port associated with the MAC address of the destination of newly received new data is identified by referring to the MAC address table, and the new data is sent from the identified connection port.
Communication system . 7. The electronic control device according to claim 3 or 6 ,
A MAC address table is updated in which the MAC address of the electronic control device that is the sender of the past data received in the past is associated with the connection port that is a connection port for connecting the electronic control devices via a communication line and that received the past data, to associate the past data received within a predetermined time from the present, and the connection port associated with the MAC address of the destination of newly received new data is identified by referring to the MAC address table, and the new data is sent from the identified connection port.
Electronic control unit.