In-vehicle network system

Abstract

This in-vehicle network system comprises: a plurality of nodes for each of which a different identification number is set and each of which is connected to a bus; an operation mode determination unit which determines an operation mode of communication in the bus; and a communication cycle setting unit which sets a cycle of the communication in the bus. The operation mode determination unit selects either a data communication mode in which the communication is performed by the nodes in accordance with an order determined in the identification number or a setting mode in which the communication cycle setting unit sets the cycle of the communication. When the operation mode determination unit has selected the setting mode, the communication cycle setting unit calculates a node number of the nodes connected to the bus, and sets the cycle of the communication according to the calculated node number.

Description

In-vehicle network system

[0001] The present invention relates to an in-vehicle network system.

[0002] In recent years, in autonomous driving, it is expected that the vehicle system will normally control driving and monitor the surroundings, while the driver will take control in an emergency. Therefore, it is essential to ensure safety on the system side during the time from when the system detects a malfunction until control of the vehicle is transferred to the driver. At the same time, as vehicle systems become more sophisticated, the number of sensors and actuators installed is increasing, and further functions such as system self-diagnosis are being expanded. This has resulted in improved processing power for the CPU that manages the vehicle system, and a significant increase in the amount of data handled within the vehicle.

[0003] Ethernet (registered trademark) has been introduced as a standard for in-vehicle networks that handle large volumes of data, and networks are evolving from a one-to-one connection structure for each domain to a zone architecture with a one-to-N hierarchical structure. The zone architecture has an integrated ECU that controls vehicle driving and zone ECUs that aggregate information from sensors and actuators at each location in the vehicle, regardless of domain. Each sensor and actuator communicates with the integrated ECU via the zone ECU, and is constructed from a backbone network that connects between zone ECUs and between integrated ECUs, and an edge network that connects zone ECUs with sensors and actuators.

[0004] Edge networks require the connection of multiple sensors and actuators, but in order to keep the number of wire harnesses to a minimum, bus networks are used, which connect multiple nodes to a single bus and enable communication with many sensors and actuators, ensuring real-time performance.

[0005] However, when multiple nodes are connected to a single cable, simultaneous data transmission can prevent normal communication. For example, in Ethernet and other systems, if a data collision occurs, the system waits a random amount of time before retransmitting data. As a result, as the amount of communication data increases, collisions become more frequent, resulting in delays in the transmission of important data. For this reason, particularly in vehicle control, where real-time communication is essential, the Physical Layer Collision Avoidance (PLCA) method is adopted, which staggers the timing at which each node transmits data to avoid data collisions and data loss.

[0006] For example, Patent Document 1 below discloses a technology that uses token passive communication in which transmission authority is transferred based on ID, where each node separates high-priority events, periodic signals, and low-priority events, and selects and transmits data for the next period within each node, with urgent data being transmitted with a higher priority than periodic data. This technology also ensures timing for periodically transmitting low-priority event data, and various data can be transmitted during the timing of this low-priority event data.

[0007] Japanese Patent Application Laid-Open No. 2001-177542

[0008] In Patent Document 1, PLCA-compatible nodes and non-compatible nodes can coexist, and data can be transmitted from non-PLCA-compatible nodes, allowing normal Ethernet frames to be transmitted during idle time when the PLCA-compatible nodes are not. This creates a risk of intrusion into the vehicle system from unauthorized connected nodes. In light of this, an object of the present invention is to provide an in-vehicle network system that reduces risk by automatically optimizing the beacon intervals in each edge network.

[0009] The in-vehicle network system comprises a plurality of nodes, each assigned a different identification number and each connected to a bus; an operation mode determination unit that determines the operation mode of communication on the bus; and a communication cycle setting unit that sets the cycle of the communication on the bus, wherein the operation mode determination unit selects either a data communication mode in which the nodes communicate according to an order determined by the identification numbers, or a setting mode in which the communication cycle setting unit sets the cycle of the communication, and when the setting mode is selected by the operation mode determination unit, the communication cycle setting unit calculates the number of nodes connected to the bus and sets the communication cycle according to the calculated number of nodes.

[0010] According to the present invention, it is possible to provide an in-vehicle network system that reduces risks by automatically optimizing the intervals between beacons in each edge network.

[0011] 3. A connection diagram of an edge network according to a first embodiment of the present invention. 4. A control flow of an in-vehicle network system according to a first embodiment of the present invention. 5. A connection diagram of an edge network according to a second embodiment of the present invention. 6. A control flow of an in-vehicle network system according to a second embodiment of the present invention. 7. A connection diagram of an edge network after execution of the setting mode in the control flow of FIG. 5. 8. A data transmission image diagram according to a second embodiment of the present invention. 9. A configuration diagram of an edge terminal according to a third embodiment of the present invention. 10. A data transmission image diagram according to the third embodiment of the present invention. 11. A configuration diagram of an edge terminal according to a fourth embodiment of the present invention. 12. A data transmission image diagram according to the fourth embodiment of the present invention.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0013] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0014] (First embodiment and overall configuration) (FIGS. 1 to 3) In a vehicle, an edge network that connects an ECU to sensors and actuators is configured to be connected to each communication terminal 11 (hereinafter referred to as a node) via a bus network 10. In the PLCA system, a different identification number (ID number) is assigned to each node 11, and as shown in FIG. 1, the nodes 11 are designated ID:0, ID:1, ID:2, ..., ID:N. Of the nodes 11 connected to the bus network 10, only the node designated ID:0 has the authority to transmit data as the coordinator node of the PLCA and manages data communication in the bus network 10. Therefore, when a PLCA bus cycle is started, the node 11 designated ID:0 is given the authority to transmit to each node 11 in the order of the assigned ID numbers, and the node 11 transmits data only while it has the authority to transmit.

[0015] As shown in the data transmission image of Figure 3(a), first, node 11 with ID: 0 transmits a beacon signal (transmission cycle start signal 12) to the bus network 10, which marks the start of a PLCA cycle, thereby starting a communication cycle. Then, node 11 with ID: 0 transfers the transmission authority to node 11 with the next ID number, ID: 1. The time during which the transmission authority is transferred is a silence time 12a. Node 11 with ID: 1 that has the transmission authority transmits data and then transfers the transmission authority to the next node 11. This transfer of transmission authority is repeated until the transmission authority has been transferred down to the node 11 with the last ID number, and one PLCA bus cycle is completed.

[0016] Whenever a node 11 does not have transmission authority, it is in a receiving state and monitors data on the bus network 10. In other words, even if it has data to send and no data from other communication terminals 11 is flowing on the network, it cannot send data unless it has transmission authority. If a node 11 that has transmission authority does not have data to send, it transfers transmission authority to the node 11 with the next ID number after a certain period of time has passed.

[0017] After one PLCA cycle is completed, the node 11 with ID: 0 transmits a beacon signal (transmission cycle start signal 12) again to start the next PLCA cycle, thereby starting the next PLCA bus cycle. In this way, in a PLCA bus cycle, transmission authority is transferred between nodes, and the nodes that can transmit are limited, thereby avoiding collisions between transmission data.

[0018] In the PLCA system, if the number of nodes with assigned ID numbers exceeds the number of nodes actually connected to the network, idle time (no data time) increases in the network, as shown in Figure 3(a), providing transmission opportunities to non-PLCA-compliant nodes. In other words, because PLCA-compliant nodes and non-PLCA-compliant nodes can coexist, idle time can allow data intrusion into the network from external sources, such as viruses via data ethernet. This is particularly true when a vehicle has fewer sensors than usual. This can lead to malicious nodes continuously transmitting large amounts of data, for example, monopolizing the network without giving other nodes an opportunity to transmit data, congesting the network for the entire vehicle, potentially preventing normal vehicle control data from being transmitted or introducing viruses or other malicious programs that disrupt vehicle control.

[0019] Therefore, as soon as the last node with the connected ID has finished transmitting, it is necessary to transmit a beacon signal to start the next PLCA bus cycle immediately, so as not to leave any idle time as shown in Fig. 3(a). To achieve this, since the timing of transmitting a beacon signal from node 11 with ID: 0 that starts the PLCA bus cycle depends on the number of connected nodes, it is necessary to set the number of nodes transmitting data to node 11 with ID: 0.

[0020] Regarding the above measures, FIG. 2 illustrates a control flow in which the communication cycle setting unit in the present invention automatically shifts to a setting mode in which the number of nodes connected to each network is counted so as not to leave any idle time in the communication cycle.

[0021] In the bus network 10, the in-vehicle network system has an operation mode determination unit and a communication cycle setting unit (not shown). The operation mode determination unit determines the operation mode of data communication. The communication cycle setting unit sets the cycle of data communication in the bus network 10.

[0022] First, in step S1, the operation mode determination unit determines whether to execute the communication mode. Based on this determination, the operation mode determination unit selects either a data communication mode in which data is communicated from the node 11 in the order determined by the identification number, or a setting mode in which a cycle is set by the communication cycle setting unit.

[0023] If it is determined in step S1 that the communication mode is to be executed (Yes), communication using the PLCA bus cycle is started in step S2. If it is determined in step S1 that the communication mode is not to be executed (No), normal Ethernet communication (CSMA / CD communication) is started in step S3, and a setting mode is started in which the control period of the beacon is set by the communication period setting unit.

[0024] Next, in step S4, it is determined whether the target node 11 is the node 11 with ID: 0. If the node 11 is ID: 0 (Yes), in step S5 the communication cycle setting unit checks the maximum ID value of the connected nodes 11 in the received frame, and in step S6 sets the checked maximum ID value to the node 11 with ID: 0 as the maximum number of nodes that can be connected. A cycle is set according to the maximum number of nodes calculated and set in this way, and communication using the PLCA bus cycle is started.

[0025] If the target node 11 does not have ID: 0 in step S4, the node 11 transmits its own node ID number to the communication cycle setting unit in step S8. The communication cycle setting unit transmits the largest ID value from the received node ID numbers to the node 11 with ID: 0. This allows the node 11 with ID: 0 to check the ID values ​​of each node 11 and confirm the number of nodes connected to the network, calculate and set the number of nodes based on the received ID numbers, and start communication using the PLCA bus cycle in step S9.

[0026] By executing the control flow as described above, the beacon control period is determined based on the number of nodes connected to the network counted in the setting mode, and by matching this with the maximum number of nodes connected to the node with ID: 0 and executing communication in the PLCA mode, a PLCA bus cycle can be realized in which beacons can be transmitted at optimal timing. As shown in Figure 3(b), after data is transmitted from node 11 with ID: N and the silence time has elapsed and one cycle has ended, the idle time is shortened and the next transmission cycle start signal 12 can be received immediately.

[0027] In this way, even if a malicious node that is not compatible with PLCA connects to the network, it is prevented from interfering with the vehicle system by not providing an opportunity for data transmission, thereby ensuring the safety of the vehicle.

[0028] Second Embodiment (FIGS. 4 to 7) Among the multiple nodes 11 connected to ID: 0 via the bus network 10, there may be a node with an available ID in the order of the node identification numbers. For example, if there is no node 11 with ID: 2 as shown in FIG. 4, an available time (no data time) will be created as shown in the data transmission image of FIG. 7(a), creating a risk of receiving unauthorized data from a node that does not support PLCA. In this case, as shown in FIG. 6, the communication cycle setting unit changes the ID number of the node (ID: N) with the maximum ID number to ID: 2, which is an available number, and moves the node 11 with the changed ID to a node 11 with an available ID, thereby preventing the intrusion of malicious data.

[0029] 5 shows the control flow of the second embodiment. First, in step S10, the operation mode determination unit determines whether or not to execute the communication mode. If it determines that the communication mode should be executed (Yes), communication using the PLCA bus cycle is started in step S11. If it determines that the communication mode should not be executed (No), normal Ethernet communication (CSMA / CD communication) is started in step S12, and the process moves to the setting mode of the communication cycle setting unit.

[0030] Next, in step S13, it is determined whether the target node 11 has ID: 0. If the target node 11 has ID: 0 (Yes), the communication cycle setting unit checks the maximum value of the ID of the connected node 11, and in step S15 sets the maximum number of connected nodes to the node 11 with ID: 0.

[0031] After setting the maximum node number to node 11 with ID: 0, the communication cycle setting unit determines in step S16 whether there is a node with an available ID in the order of the nodes 11. If it determines that there is no node 11 with an available ID number (Yes), communication using a PLCA bus cycle is started. If it determines that there is a node 11 with an available ID number (No), in step S18 the communication cycle setting unit requests the node 11 with the maximum ID value to change its ID number to an available ID number. Once the node 11 with the maximum ID value has changed to an available ID number, step S16 is repeated to determine whether there is a node 11 with an available ID.

[0032] If it is determined in step S13 that the target node 11 does not have ID: 0 (No), the ID of that node 11 is sent to the communication cycle setting unit, and the communication cycle setting unit sends the set node number to the node 11 with ID: 0. In step S20, the communication cycle setting unit determines whether there is a request to change the ID of the node 11. If there is no ID change request (Yes), the process proceeds directly to communication using the PLCA bus cycle in step S21. If there is an ID change request (No), the communication cycle setting unit changes the ID of the target node 11 in step S22, and the process proceeds to communication using the PLCA bus cycle in step S21.

[0033] By making such settings, as shown in Fig. 7(a), the idle time in the communication cycle due to the absence of node 11 with ID:2 can be filled by node 11 whose ID:N has been changed to ID:2 as shown in Fig. 7(b), even if the maximum number of nodes set for node 11 with ID:0 is greater than the number of nodes connected to the bus network 10. Also, the efficiency of the network bandwidth can be improved.

[0034] (Third embodiment) (Figs. 8 and 9) As shown in Fig. 7(a) above, when an available time period occurs, the available node 11 has no data (packets), so the communication of that node 11 is skipped and authority is transferred to the next communication, but this causes a shift in the overall transmission period as shown in Fig. 9(a). Therefore, in this embodiment, in order to make the beacon period constant, data is transmitted randomly during the available time period to eliminate the shift in the transmission period.

[0035] The node 11 has a transmission data storage unit 17, a random data generation unit 18, a transmission data selection unit 20, and a data transmission unit 19. The data transmission unit 19 is connected to the bus network 10. The transmission data storage unit 17 stores transmission data transmitted to the bus network 10. The random data generation unit 18 creates random data to be transmitted to the bus network 10. The transmission data selection unit 20 selects data to be transmitted.

[0036] If there is data that is not stored in the transmission data memory unit 17, the transmission data selection unit 20 obtains random data from the random data generation unit 18 and transmits the random data to the bus network 10 via the data transmission unit 19.

[0037] In this way, when the setting mode is selected by the operation mode determination unit, the node 11 with ID: 0 transmits information about the data free time (silence time) that occurs during the cycle to the communication cycle setting unit, and as shown in Figure 9 (b), the node 11 connected to the bus network 10 has the same setting for the time to transfer the transmission authority after data transmission and the primary authority retention time for transferring the transmission authority when there is no data to transmit, so that the beacon transmission cycle can always be constant, allowing the PLCA bus cycle to operate normally.

[0038] (Fourth embodiment) (FIGS. 10 and 11) If the maximum number of nodes set for node 11 with ID: 0 is greater than the number of network nodes, there is a possibility of unauthorized data intrusion because there is free time in the cycle. Therefore, it is determined whether there is free time for specified data in the cycle, and if it is determined that there is no data (packet) longer than the specified time, a countermeasure is taken in which random data 14 is filled in.

[0039] The node 11 includes a transmission data storage unit 17, a random data generation unit 18, a transmission data selection unit 20, and a data transmission unit 19. The node 11 further includes a network data monitoring unit 21 and an available time measurement unit 22.

[0040] The network data monitoring unit 21 monitors the communication status of the bus network 10. The idle time measurement unit 22 measures idle time (no data time) from the packet communication status in the bus network 10 via the network data monitoring unit 21. When the idle time measurement unit 22 measures a predetermined idle time in a communication cycle, it outputs a command to the transmission data selection unit 20 to insert random data 14 into the cycle.

[0041] As shown in the data transmission diagram of FIG. 11 , a communication cycle begins with a transmission cycle start signal 12 and is filled with data for ID: 0, ID: 1, ID: 2, ..., and ID: N-m. However, if the maximum number of nodes set for node ID: 0 11 is greater than the number of network nodes, there will be additional data free time. Therefore, when the free time measurement unit 22 measures that free time Ta has elapsed since the data for ID: N-m, it instructs the transmission data selection unit 20 to insert random data 14. If there is still data free time until the next communication cycle, the free time measurement unit 22 similarly measures that free time Ta has elapsed and instructs the transmission data selection unit 20 to insert random data 14, and repeats the process of transmitting random data to the bus network 10. This fills the free time until the next communication cycle and allows the beacon period to be constant, thereby preventing the intrusion of unauthorized data.

[0042] Fifth Embodiment (FIG. 12) In communication using the PLCA system, the node 11 with ID: 0 in the edge network is a coordinator node that manages time during a communication cycle. Therefore, by configuring the node 11 with ID: 0 within the zone ECU 15, which is the connection between the backbone network 13 and the edge network, it becomes easier to detect abnormalities, such as when the node 11 with ID: 0 fails and no longer transmits a beacon. Furthermore, because error codes and the like can be transmitted to a higher-level system without going through a bus connection, it becomes easier for the higher-level vehicle system to control the network and ensure communication reliability.

[0043] (Sixth embodiment) (FIG. 13) The operation mode determination unit selects the setting mode only when maintenance is being performed on the vehicle 100. Specifically, for example, the vehicle 100 is equipped with an OBD (On Board Diagnostics) device or the like used for vehicle maintenance, and the operation mode determination unit selects the setting mode when the setting mode changeover switch 16 is externally connected to the OBD device or the like. Otherwise, the PLCA mode is always selected. In this manner, only specialists who inspect the system of the vehicle 100 are authorized to switch between the communication mode and the setting mode, thereby preventing unauthorized access to the in-vehicle network system from other parties.

[0044] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0045] (1) A vehicle-mounted network system is provided, comprising: a plurality of nodes 11 each assigned a different identification number and each connected to a bus 10; an operation mode determination unit that determines an operation mode for communication on the bus 10; and a communication cycle setting unit that sets a cycle for communication on the bus 10, wherein the operation mode determination unit selects either a data communication mode in which the nodes 11 communicate in an order determined by the identification numbers, or a setting mode in which the communication cycle setting unit sets a cycle for communication, and when the operation mode determination unit selects the setting mode, the communication cycle setting unit calculates the number of nodes 11 connected to the bus 10 and sets the communication cycle according to the calculated number of nodes. In this way, an in-vehicle network system can be provided that achieves risk reduction by automatically optimizing the intervals between beacons in each edge network.

[0046] (2) When the setting mode is selected by the operation mode determination unit, the nodes 11 transmit their assigned identification numbers to the communication cycle setting unit, and the communication cycle setting unit calculates the number of nodes based on the received identification numbers. In this way, the number of nodes set in the coordinator node can be made to match the number of nodes connected to the network.

[0047] (3) Of the multiple nodes 11, a coordinator node that manages communications is provided at the connection 15 between the backbone network 13 and the edge network. This makes it easier to discover abnormalities and ensures communication reliability.

[0048] (4) When the setting mode is selected by the operation mode determination unit, information about free time of data occurring during the communication cycle is transmitted from the coordinator node to the communication cycle setting unit. In this way, measures can be taken to fill the free time (no data time).

[0049] (5) If there is an available identification number in the order of the identification numbers of the multiple nodes 11, the communication cycle setting unit changes the identification number of the node 11 with the largest identification number to the available identification number. In this way, the available time (time with no data) can be filled, thereby achieving efficient network bandwidth.

[0050] (6) The system includes a random data generation unit 18 that generates random data 14 to be transmitted to the bus 10, a transmission data selection unit 20 that selects data to be transmitted to the bus 10, and a transmission data storage unit 17 that stores data transmitted to the bus 10, and when the transmission data selection unit 20 determines that there is data that is not stored in the transmission data storage unit 17, it acquires the random data 14 from the random data generation unit 18 and transmits the random data 14 to the bus 10. This allows the beacon transmission period to be always constant, allowing the PLCA bus cycle to operate normally.

[0051] (7) The system has an idle time measurement unit 22 that determines whether there is a predetermined idle time during the communication cycle, and when the idle time measurement unit 22 determines that there is a predetermined idle time during the communication cycle, it outputs a command to the transmission data selection unit 20 to acquire random data from the random data generation unit 18 and transmit the random data to the bus 10. By doing so, the beacon cycle can be made constant, thereby preventing the intrusion of unauthorized data.

[0052] (8) The operation mode determination unit selects the setting mode when the OBD device installed in the vehicle is used, thereby preventing the general public from accessing the in-vehicle network system.

[0053] The present invention is not limited to the above-described embodiments, and various modifications and combinations of other configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted.

[0054] REFERENCE SIGNS LIST 10 Bus network 11 Communication terminal (node) 12 Transmission cycle start signal 12a Silence time 13 Backbone network 14 Random data 15 Zone ECU 16 Setting mode changeover switch 17 Transmission data storage unit 18 Random data generation unit 19 Data transmission unit 20 Transmission data selection unit 21 Network data monitoring unit 22 Free time measurement unit 100 Vehicle

Claims

1. An in-vehicle network system comprising: a plurality of nodes, each assigned a different identification number and each connected to a bus; an operation mode determination unit that determines an operation mode for communication on the bus; and a communication cycle setting unit that sets a cycle of the communication on the bus, wherein the operation mode determination unit selects either a data communication mode in which the nodes communicate in an order determined by the identification numbers, or a setting mode in which the communication cycle setting unit sets the cycle of the communication, and when the setting mode is selected by the operation mode determination unit, the communication cycle setting unit calculates the number of the nodes connected to the bus, and sets the communication cycle in accordance with the calculated number of nodes.

2. An in-vehicle network system as described in claim 1, wherein, when the setting mode is selected by the operation mode determination unit, the plurality of nodes transmit the identification number assigned to the node to the communication cycle setting unit, and the communication cycle setting unit calculates the number of nodes based on the received identification number.

3. An in-vehicle network system according to claim 1, wherein a coordinator node that manages the communications among the plurality of nodes is provided at a connection between a backbone network and an edge network.

4. An in-vehicle network system as described in claim 3, wherein, when the setting mode is selected by the operation mode determination unit, information on data free time occurring during the communication cycle is transmitted from the coordinator node to the communication cycle setting unit.

5. An in-vehicle network system as described in claim 1, wherein, when there is an available identification number in the sequence of the identification numbers of the plurality of nodes, the communication cycle setting unit changes the identification number of the node having the largest identification number value to the available identification number.

6. An in-vehicle network system as described in claim 1, comprising: a random data generation unit which generates random data to be transmitted to the bus; a transmission data selection unit which selects data to be transmitted to the bus; and a transmission data storage unit which stores the data transmitted to the bus, wherein when the transmission data selection unit determines that there is data that is not stored in the transmission data storage unit, it obtains the random data from the random data generation unit and transmits the random data to the bus.

7. An in-vehicle network system as described in claim 6, further comprising an idle time measurement unit which judges whether or not there is a predetermined amount of idle time during the communication cycle, and when the idle time measurement unit judges that there is the predetermined amount of idle time during the communication cycle, the idle time measurement unit outputs a command to the transmission data selection unit to obtain the random data from the random data generation unit and transmit the random data to the bus.

8. An in-vehicle network system according to claim 1, wherein the operation mode determination unit selects the setting mode when an OBD device mounted in the vehicle is used.

Images