JP7794070B2 - Vehicle Network - Google Patents

Description

The present invention relates to a vehicle network in which multiple communication devices mounted on a vehicle are connected via communication lines.

Conventional vehicle networks include AD/ADAS-compatible in-vehicle Ethernet networks that receive multiple data sources, such as LiDAR data, camera footage, and V2X communications, using multiple receiving devices such as ECUs. Note that LiDAR is an abbreviation for Light Detection And Ranging, V2X is an abbreviation for Vehicle to Everything (X), ECU is an abbreviation for Electric Control Unit, and AD/ADAS is an abbreviation for Automated Driving/Advanced Driver Assistance System. Also, Ethernet is a registered trademark.

In such AD/ADAS-compatible vehicle networks, it is desirable for each receiving device to synchronize the time at which processing is performed using data acquired at a specific time. However, due to delay differences caused by differences in data transmission paths, differences in the time at which data is received between each receiving device, even if the data was acquired at the same time, can occur. If each receiving device operates under these conditions, differences will occur between the timing at which data acquired at the same time is used, i.e., the time at which processing is performed using data acquired at the same time.

JP 2011-223360 A

Conventional technologies such as AVB and TSN can be considered as solutions to the issues described above. AVB stands for Audio Video Bridging, and TSN stands for Time Sensitive Network. AVB synchronizes the display times of video and audio by including the shooting time and the designated time for display on the receiving side in the data portion of the Ethernet frame from the transmitting side, and by always adding a fixed margin to this designated time, it is possible to absorb delay differences.

However, when considering applying AVB to an AD/ADAS-compatible vehicle network, the following problem arises. While an AD/ADAS-compatible vehicle network requires the lowest possible latency, the display latency in AVB is fixed to a set margin time, resulting in a problem of latency greater than the actual latency difference. On the other hand, while TSN makes it possible to achieve low-latency time synchronization between multiple devices, it requires high performance in the interface physical layer, which creates the problem of significant costs involved in replacing existing devices.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a vehicle network that can synchronize the timing of using data from the same time between receiving devices while keeping delays low and without increasing costs.

The vehicle network described in claim 1 is configured such that multiple communication devices (2 to 7) mounted on a vehicle are connected via a communication line (8). In this case, each of the multiple communication devices is configured to be able to synchronize time with one another. Here, among the multiple communication devices, a communication device that transmits specific data via the communication line is designated as a transmitter device (2, 3, 10), and a communication device that receives and uses the specific data via the communication line is designated as a receiver device (6, 7, 20, 30, 40, 50). The transmitter device includes a data transmitter unit (11) that transmits the specific data after adding transmission information indicating a transmission time, which is the time the specific data was acquired or the time the specific data was transmitted.

The receiving device also includes a delay information transmitting unit (21, 31, 41) and a data receiving unit (22, 32, 52). The delay information transmitting unit calculates a reception delay time, which is the difference between the transmission time indicated by the transmission information assigned to the received specific data and the reception time, which is the time when the specific data was received, and transmits delay information indicating the calculated reception delay time to another receiving device. The data receiving unit receives and uses the specific data transmitted from the transmitting device, and includes a buffer (22a) with a queue structure that can store the specific data.

In the above configuration, when the data receiving unit receives the specific data transmitted from the transmitting device, if the reception delay time calculated by the delay information transmitting unit is less than a maximum other device delay time, which is the longest time among the reception delay times represented by the delay information received from the other receiving devices, it adds the received specific data to the end of the buffer, and if the reception delay time calculated by the delay information transmitting unit is equal to or greater than the maximum other device delay time, it uses the received specific data without adding it to the buffer. Furthermore, when the difference between the transmission time represented by the transmission information assigned to the specific data stored at the top of the buffer and the current time is equal to or greater than the maximum other device delay time, the data receiving unit retrieves and uses the specific data stored at the top of the buffer.

With the above configuration, each receiving device can synchronize the timing of using data at the same time, based on its own reception delay time and the reception delay times of other devices indicated by delay information transmitted from those other receiving devices, so as to match the timing of the receiving device with the longest reception delay time. In this case, there is no risk of excessive delay, as with AVB, and there is no need for significant costs to replace existing devices, as with TSN. Therefore, with the above configuration, the excellent effect of keeping delays low and synchronizing the timing of using data at the same time between receiving devices can be achieved without increasing costs.

FIG. 1 is a diagram illustrating a network configuration according to a first embodiment; FIG. 1 is a diagram schematically illustrating a configuration of a transmission device according to a first embodiment; FIG. 1 is a diagram schematically illustrating a configuration of a receiving device according to a first embodiment. FIG. 10 is a diagram showing an example of the content of a first process executed by the receiving device according to the first embodiment; FIG. 10 is a diagram showing an example of the content of a second process executed by the receiving device according to the first embodiment; FIG. 10 is a diagram showing an example of the content of a third process executed by the receiving device according to the first embodiment; FIG. 10 is a diagram showing an example of a specific operation related to synchronization of the execution times of processes in each receiving device according to the first embodiment; FIG. 10 is a diagram schematically illustrating the configuration of a receiving device according to a second embodiment. FIG. 10 is a diagram showing an example of the content of a first process executed by a receiving device according to a second embodiment; FIG. 10 is a diagram showing an example of the content of a third process executed by the receiving device according to the second embodiment. FIG. 10 is a diagram schematically illustrating the configuration of a receiving device according to a third embodiment. FIG. 11 is a diagram showing an example of the content of a first process executed by a receiving device according to a third embodiment; FIG. 11 is a diagram showing an example of the content of a third process executed by the receiving device according to the third embodiment. FIG. 10 is a diagram schematically illustrating the configuration of a receiving device according to a fourth embodiment. FIG. 13 is a diagram showing an example of the content of a first process executed by a receiving device according to a fourth embodiment;

Hereinafter, several embodiments will be described with reference to the drawings. Note that substantially the same components in each embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.
(First embodiment)
The first embodiment will be described below with reference to FIGS.

As shown in FIG. 1, network 1 of this embodiment is an example of a vehicle network, in which a camera 2, LiDAR 3, pre-processing ECU 4, sub-ECU 5, control ECU 6, and control ECU 7 mounted on a vehicle such as an automobile are connected via communication lines 8. Each of camera 2, LiDAR 3, pre-processing ECU 4, sub-ECU 5, control ECU 6, and control ECU 7 has a clock synchronized by means of gPTP or the like, allowing them to synchronize their time with each other. Note that PTP is an abbreviation for Precision Time Protocol.

The camera 2, LiDAR 3, pre-processing ECU 4, sub-ECU 5, control ECU 6, and control ECU 7 function as communication devices and perform Ethernet communication via communication line 8. If, of these multiple communication devices, the communication devices that transmit data via communication line 8 are defined as transmitters and the communication devices that receive data via communication line 8 are defined as receivers, then the camera 2 and LiDAR 3 function as transmitters, and the control ECU 6 and control ECU 7 function as receivers.

The above-mentioned transmitting device and receiving device can employ configurations such as those shown in Figures 2 and 3. As shown in Figure 2, the transmitting device 10 has functional blocks such as a data transmitting unit 11. The data transmitting unit 11 transmits data after attaching transmission information indicating the transmission time, which is the time at which the data is to be transmitted. Note that in cases where the delay time between when the transmitting device 10 acquires the data and when it transmits it is extremely short, the time when the data was acquired can also be used as the transmission time.

As shown in FIG. 3, the receiving device 20 includes functional blocks such as a delay information transmitting unit 21 and a data receiving unit 22. The delay information transmitting unit 21 calculates the reception delay time, which is the difference between the transmission time indicated by the transmission information attached to the received data and the reception time, which is the time the data was received. The delay information transmitting unit 21 then transmits, i.e., broadcasts, the delay information indicating the calculated reception delay time to all other receiving devices.

In this case, the delay information transmission unit 21 is configured to transmit delay information periodically at a predetermined specified time interval. The delay information transmission unit 21 is equipped with a timer 21a for counting the specified time. The interval at which the delay information transmission unit 21 transmits delay information, i.e., the specified time, can be set to a different time for each receiving device 20. The delay information transmission unit 21 can also transmit delay information when it receives data transmitted from the transmitting device 10.

The data receiving unit 22 receives and uses data transmitted from the transmitting device 10. Note that, in this specification, data transmitted from the transmitting device 10 is sometimes referred to as input data. The data receiving unit 22 has a queue structure capable of storing input data, i.e., a first-in, first-out buffer 22a. Note that, in this specification, the buffer 22a is sometimes referred to as a queue.

The data receiving unit 22 is also configured to receive delay information, which is data representing reception delay information transmitted from other receiving devices. Note that in this specification, delay information transmitted from other receiving devices is sometimes referred to as other device delay information. The data receiving unit 22 is equipped with a memory unit 22b that stores other device delay information. For other device delay information transmitted from the same other receiving device, the data receiving unit 22 is configured to store it in a manner that overwrites previous information so that the most recent information remains in the memory unit 22b. As a result, the latest other device delay information for each other receiving device is stored in the memory unit 22b.

When the data receiving unit 22 receives data transmitted from the transmitting device 10, if the reception delay time of its own device calculated by the delay information transmitting unit 21 is less than the other device's maximum delay time, which is the longest reception delay time represented by the other device delay information, which is delay information received from other receiving devices, the data receiving unit 22 adds the received data to the end of the buffer 22a; if the reception delay time of its own device calculated by the delay information transmitting unit 21 is equal to or greater than the other device's maximum delay time, the data receiving unit 22 uses the received data without adding it to the buffer 22a. When the difference between the transmission time represented by the transmission information attached to the data stored at the top of the buffer 22a and the current time is equal to or greater than the other device's maximum delay time, the data receiving unit 22 retrieves and uses the data stored at the top of the buffer 22a.

Each functional block of the transmitting device 10 and the receiving device 20 is realized by the CPU of the transmitting device 10 and the receiving device 20 executing a computer program stored on a non-transient tangible storage medium and performing processing corresponding to the computer program, i.e., realized by software. Note that at least a portion of each functional block may also be realized by hardware.

Camera 2 captures images of the area ahead of the vehicle and transmits data A representing the captured image of the area ahead of the vehicle to pre-processing ECU 4 and control ECU 7 after attaching transmission information. LiDAR 3 measures the position of objects ahead of the vehicle and transmits data B representing object position information obtained from this measurement to sub-ECU 5 after attaching transmission information. Pre-processing ECU 4 is an ECU for image pre-processing and receives data A. Pre-processing ECU 4 recognizes the type of object in the received data A and transmits data A' representing the object recognition information obtained through this recognition to sub-ECU 5. Examples of object types include preceding vehicles and pedestrians. In this case, data A' is attached with the same transmission information as that attached to data A.

The sub-ECU 5 functions as a switching hub, combining multiple signals transmitted from the LiDAR 3 sensor and the pre-processing ECU 4, another ECU, to the control ECU 6 into a single path. That is, the sub-ECU 5 receives data A' and data B, and transmits data A" and data B' corresponding to the received data to the control ECU 6. In this case, data A" is assigned the same transmission information as that assigned to data A and A', and data B' is assigned the same transmission information as that assigned to data B.

Control ECU 6 is a control ECU for creating a driving plan, and receives data A" and data B'. Control ECU 6 links data A" representing object recognition information with data B' representing object position information, and uses this to recognize the situation ahead of the vehicle and determine a driving pattern. In this case, performing the process of determining the driving pattern corresponds to using data A" and data B'.

Control ECU 7 is a control ECU for lane departure prevention, which detects the lane position from data A representing the image ahead of the vehicle, and performs processing to intervene in steering operation to correct the lane departure based on that detection. In this case, performing processing to intervene in steering operation corresponds to using data A.

In the above configuration, a steering control unit (not shown) that controls the steering of the vehicle is configured to accept steering control commands transmitted from both control ECU 6 and control ECU 7. In this embodiment, the steering control unit has a judgment criterion that prioritizes the command from control ECU 6 when commands are accepted simultaneously from both control ECU 6 and control ECU 7.

In this configuration, for example, if there is an obstacle ahead of the vehicle and the driver, i.e., the operator of the vehicle, performs a steering operation that causes the vehicle to temporarily deviate from the lane to avoid the obstacle, the control ECU 6 will recognize the obstacle and issue a command to the steering control unit to execute an operation to avoid the obstacle, while the control ECU 7 will detect only the lane departure and issue a command to the steering control unit to execute an operation to return the vehicle to the original lane. In this case, the steering control unit has criteria that prioritize commands from the control ECU 6, so it can prioritize the operation to avoid the obstacle.

Next, the processing performed by the receiving device 20 in the above configuration, i.e., the control ECU 6 and control ECU 7, will be described with reference to Figures 4 to 6. Each receiving device 20 performs the first processing, the second processing, and the third processing in parallel.

<Regarding the first process>
The first process is, for example, a process shown in Fig. 4, and is a process related to the use or storage of received data. The first process is executed every time data is received by the data receiving unit 22. First, in step S101, it is determined whether the received data is input data, which is data transmitted from the transmitting device 10.

Here, if the received data is not input data, that is, if the received data is other device delay information, the result is "NO" in step S101 and the process proceeds to step S102. In step S102, the received other device delay information is stored in memory unit 22b. After step S102 is executed, this process ends. On the other hand, if the received data is input data, the result is "YES" in step S101 and the process proceeds to step S103.

In step S103, the reception delay time of the currently received input data is calculated. That is, in step S103, the delay information transmission unit 21 calculates the reception delay time of the input data. After step S103 is executed, the process proceeds to step S104, where it is determined whether the reception delay time Ta of the device itself calculated in step S103 is equal to or longer than the other device maximum delay time Tb, which is the longest time among the reception delay times represented by the other device delay information stored in the memory unit 22b. In other words, in step S104, it is determined whether the reception delay time Ta of the device itself is equal to or longer than the other device maximum delay time Tb.

Here, if the reception delay time Ta of the own device is equal to or greater than the maximum delay time Tb of the other device, step S104 returns "YES" and the process proceeds to step S105. In other words, if the transmission time of the currently received input data is the same as or later than the transmission time of the input data received by the other receiving device, step S104 returns "YES" and the process proceeds to step S105. In step S105, a process using the currently received input data is executed. In the case of control ECU 6, the process using the input data is a process for determining a driving pattern, and in the case of control ECU 7, it is a process for intervening in steering operation.

In other words, in this case, the data receiving unit 22 uses the currently received input data without adding it to the queue. On the other hand, if the reception delay time Ta of the own device is less than the maximum delay time Tb of other devices, the result is "NO" in step S104 and the process proceeds to step S106. In step S106, the currently received input data is added to the end of the queue. After step S105 or S106 is executed, this process ends.

<Regarding the second process>
The second process is, for example, a process shown in Fig. 5, and is a process related to retrieving received data. The second process is a process that starts when the receiving device 20 is started. Specifically, the second process is a process that starts when the vehicle is initialized by turning on the power.

First, in step S201, the difference between the current time and the transmission time indicated by the transmission information attached to the data stored at the head of the queue is calculated; that is, the reception delay time of the data stored at the head of the queue. After step S201 is executed, the process proceeds to step S202, where it is determined whether the reception delay time Tc of the data stored at the head of the queue is equal to or longer than the maximum delay time Tb of other devices. In other words, in step S202, it is determined whether the reception delay time Tc of the data stored at the head of the queue is equal to or longer than the maximum delay time Tb of other devices.

Here, if the reception delay time Tc of the data stored at the head of the queue is less than the maximum delay time Tb of other devices, step S202 returns "NO" and the determination of step S202 is executed again. On the other hand, if the reception delay time Tc of the data stored at the head of the queue is greater than or equal to the maximum delay time Tb of other devices, step S202 returns "YES" and the process proceeds to step S203. In other words, if the transmission time of the data stored at the head of the queue is not earlier than the transmission time of the input data received by the other receiving device, step S202 returns "YES" and the process proceeds to step S203.

In step S203, the data stored at the top of the queue is retrieved. After step S203 is executed, the process proceeds to step S204, where a process using the data retrieved in step S203 is executed. Similar to step S105, the process using the retrieved data is a process to determine a driving pattern in the case of control ECU 6, and a process to intervene in steering operation in the case of control ECU 7. After step S204 is executed, the process returns to step S201, and the same processes as those described above are repeated.

<Regarding the third process>
The third process is, for example, a process as shown in Fig. 6, and is a process related to transmission of delay information indicating a reception delay time. The third process is a process that is started when the receiving device 20 is started. Specifically, the third process is a process that is started when the vehicle is initialized by turning on the power.

First, in step S301, the timer 21a starts timing. After step S301 is executed, the process proceeds to step S302, where it is determined whether the timer time Td, which is the time measured by the timer 21a, is equal to or greater than the specified time Te. If the timer time Td is less than the specified time Te, the result in step S302 is "NO," and the determination in step S302 is executed again. On the other hand, if the timer time Td is equal to or greater than the specified time Te, the result in step S302 is "YES," and the process proceeds to step S303.

In step S303, the difference between the transmission time indicated by the transmission information attached to the data stored at the top of the queue and the current time is calculated, i.e., the reception delay time of the data stored at the top of the queue. After step S303 is executed, the process proceeds to step S304, where delay information indicating the reception delay time calculated in step S303 is transmitted to all other receiving devices. In other words, in step S304, the delay information is broadcast. After step S304 is executed, the process proceeds to step S305, where timer 21a is reset. After step S305 is executed, the process returns to step S301, and the same processes as those described above are repeated.

Next, an example of a specific operation relating to synchronization of the execution times of the processes in the control ECU 6 and the control ECU 7, which function as the receiving device 20, will be described with reference to FIG.
As shown in Fig. 1, the data transmitted from the camera 2 and the LiDAR 3, which function as the transmitting device 10, are provided to the control ECU 6 and the control ECU 7 via a plurality of different paths. As shown in Fig. 7, the data received by the control ECU 6 and the control ECU 7 at a given time t have different transmission times assigned to them due to the differences in the paths described above.

In Figure 7, data frames are represented by rectangles, with numbers such as 01, 02, 03, 04, 05, 06, 07, and 08 written inside them to indicate the time the data was sent. Note that smaller numbers represent earlier times. In this case, open rectangles represent data stored in buffer 22a, and rectangles filled with a dotted line pattern represent data referenced at that time, i.e., data used at that time.

As shown in Figure 7, when the current time t is "05", the transmission times of data A" and B' received by control ECU 6 are "01" and "02", respectively, and the transmission time of data A received by control ECU 7 is "03". When the current time t is "06", the transmission times of data A" and B' received by control ECU 6 are "02" and "03", respectively, and the transmission time of data A received by control ECU 7 is "04".

In this case, the control ECU 6 finds that the transmission time of data A'' is delayed by "01" relative to the transmission time of data B'. Therefore, in order to align the times of data A'' and B'', data B' is stored in the buffer 22a, and when the current time t is "06", the data is retrieved from the buffer 22a and referenced. In this way, the transmission times of data A'' and B' used by the control ECU 6 are aligned. At this time, the control ECU 6 broadcasts delay information indicating the reception delay time Δt1 of its own device, which is expressed by the following equation (1):
Δt1=06-02=4...(1)

When the control ECU 7 receives the broadcast delay information, it compares the reception delay time Δt1 indicated by the delay information with the reception delay time Δt2 of the own device expressed by the following equation (2).
Δt2=06-04=2...(2)

The control ECU 7 determines that its own device has less delay because the reception delay time Δt2 is shorter than the reception delay time Δt1 as a result of the above comparison. The control ECU 7 then stores data A in buffer 22a, and retrieves and references the data from buffer 22a when the reception delay time Δt2 of the data stored at the beginning of buffer 22a becomes equal to the reception delay time Δt1. In this case, when the current time t is "08," the reception delay time Δt2 of the data stored at the beginning of buffer 22a of the control ECU 7 becomes equal to the reception delay time Δt1 indicated by the delay information transmitted from control ECU 6.

As a result, when the current time t is "08", the transmission times of all data used by control ECU 6 and control ECU 7, i.e., data A", data B', and data A, will all match at "04". This ensures that control ECU 6 and control ECU 7 use data from the same time at the same time, thereby achieving synchronization of processing times.

According to the present embodiment described above, the following effects can be obtained.
When the data receiving unit 22 receives data transmitted from the transmitting device 10, if the reception delay time calculated by the delay information transmitting unit 21 is less than the other device's maximum delay time, which is the longest reception delay time indicated by the delay information received from the other receiving devices, the data receiving unit 22 adds the received data to the end of the buffer 22a, and if the reception delay time calculated by the delay information transmitting unit 21 is equal to or greater than the other device's maximum delay time, the data receiving unit 22 uses the received data without adding it to the buffer 22a. Furthermore, when the difference between the transmission time indicated by the transmission information added to the data stored at the top of the buffer 22a and the current time becomes equal to or greater than the other device's maximum delay time, the data receiving unit 22 retrieves and uses the data stored at the top of the buffer 22a.

With the above configuration, each receiving device 20 can align the timing of using data at the same time to match the receiving device 20 with the longest reception delay time, based on the reception delay time of its own device and the reception delay times of other devices indicated by delay information transmitted from those other receiving devices. In this case, there is no risk of excessive delay as with AVB, and there is no need for significant costs to replace existing devices as with TSN. Therefore, this embodiment has the excellent effect of keeping delays low and synchronizing the timing of using data at the same time between each receiving device 20 without increasing costs.

In the configuration of this embodiment, if the processing times of the control ECU 6 and the control ECU 7, which function as the receiving device 20, are not synchronized and the control ECU 6 uses data at a later time than the control ECU 7, the following problem will arise. That is, as described above, in the configuration of this embodiment, for example, if there is an obstacle ahead of the vehicle and the driver of the vehicle performs a steering operation that causes the vehicle to temporarily deviate from its lane to avoid the obstacle, the control ECU 6 will recognize the obstacle and provide a command to the steering control unit to perform an operation to avoid the obstacle, and the control ECU 7 will detect only the lane departure and provide a command to the steering control unit to perform an operation to return the vehicle to its original lane.

When considering this type of operational control, if control ECU 6 uses data from the same time later than control ECU 7 as described above, the steering control unit will receive a steering control command from control ECU 7 before a steering control command from control ECU 6, resulting in unintended behavior such as temporary intervention in steering to return the vehicle to the original lane where the obstacle is located.

In contrast, according to this embodiment, the execution times of processing between the control ECU 6 and the control ECU 7 are synchronized, so that a steering control command from the control ECU 7 is not given to the steering control unit before a steering control command from the control ECU 6. In this case, the steering control command from the control ECU 6 and the steering control command from the control ECU 7 are given to the steering control unit simultaneously, but as described above, if the steering control unit receives commands from both the control ECU 6 and the control ECU 7 simultaneously, the command from the control ECU 6 takes priority, thereby preventing the occurrence of unintended behavior such as that described above.

The delay information transmission unit 21 is configured to transmit delay information periodically at predetermined time intervals. This provides the following advantages compared to when delay information is transmitted upon receiving data transmitted from the transmitting device 10. That is, if delay information is transmitted upon receiving data by each receiving device 20, there is a higher possibility that the timing of broadcasting delay information will conflict between multiple receiving devices 20.

In contrast, when delay information is transmitted periodically at specified time intervals, as in this embodiment, the possibility of conflicts in the timing of broadcasting delay information between multiple receiving devices 20 can be reduced. In this case, it is also possible to set the specified time to a different time for each receiving device 20, which further reduces the possibility of such conflicts.

Second Embodiment
The second embodiment will be described below with reference to FIGS.
As shown in Figure 8, the receiving device 30 of this embodiment differs from the receiving device 20 of the first embodiment shown in Figure 3 in that it has a delay information transmitting unit 31 instead of the delay information transmitting unit 21, and a data receiving unit 32 instead of the data receiving unit 22.

Like the data receiving unit 22, the data receiving unit 32 can receive data transmitted from the transmitting device 10 and delay information transmitted from other receiving devices, and can also receive data representing change notifications to notify of changes to the network configuration. The change notification indicates that there has been a change or modification to the configuration of at least one of the multiple communication devices and communication lines 8 that make up the network 1. Such change notifications are sent manually or automatically via logic, for example, when one or both of the hardware and software related to the network 1 are changed due to a service update or the like.

Like the delay information transmitter 21, the delay information transmitter 31 calculates the reception delay time and transmits delay information representing the calculated reception delay time to all other receiving devices. However, the delay information transmitter 31 does not include the timer 21a compared to the delay information transmitter 21, and therefore the timing at which the delay information is transmitted is different. In other words, the delay information transmitter 31 transmits the delay information upon receiving a change notification such as that described above.

The receiving device 30 configured as described above performs the first process, second process, and third process, similar to the receiving device 20 of the first embodiment, but the content of the first and third processes differs from that of the first embodiment. Furthermore, in this case, the third process is included as part of the first process. The content of the first and third processes performed by the receiving device 30 of this embodiment will be described below with reference to Figures 9 and 10.

[1] First Processing As shown in Fig. 9, the first processing of this embodiment differs from the first processing of the first embodiment shown in Fig. 4 in that steps S111 and S112 are added. In the first processing of this embodiment, if step S101 returns "NO," that is, if the received data is not input data, the process proceeds to step S111. In step S111, it is determined whether the received data is other device delay information.

Here, if the received data is other device delay information, step S111 returns "YES" and the process proceeds to step S102. On the other hand, if the received data is not other device delay information, that is, if the received data is a change notification, step S111 returns "NO" and the process proceeds to step S112. In step S112, the third process is executed. After step S112 is executed, this process ends.

[2] Third Processing As shown in Fig. 10, the third processing of this embodiment differs from the third processing of the first embodiment shown in Fig. 6 in that steps S301, S302, and S305 are omitted. When the third processing of this embodiment starts, step S303 is executed first. In step S303, the reception delay time of the data stored at the head of the queue is calculated. After execution of step S303, the process proceeds to step S304, where delay information representing the reception delay time calculated in step S303 is broadcast. After execution of step S304, this processing ends.

As explained above, the delay information transmission unit 31 of this embodiment is configured to transmit delay information upon receiving a change notification indicating that there has been a change or modification to at least one of the multiple communication devices and communication lines 8 that make up network 1. This configuration provides the following advantages: In other words, in network 1, which is an example of a vehicle network in which Ethernet communication is carried out via communication lines 8, it is unlikely that the delay between the same routes will change significantly unless there is a change in its components, i.e., the multiple communication devices and communication lines 8.

In other words, in network 1, unless there are changes in its components, the reception delay time at each receiving device 30 will remain roughly constant and will not change significantly. Therefore, if delay information were to be transmitted when data transmitted from the transmitting device 10 was received, the frequency of broadcasts would increase, which could increase the processing load on the receiving device 30. In contrast, if delay information is transmitted when a change notification is received, as in this embodiment, the frequency of broadcasts can be kept low, and as a result, the processing load on the receiving device 30 can be reduced.

(Third embodiment)
The third embodiment will be described below with reference to FIGS.
As shown in Figure 11, the receiving device 40 of this embodiment differs from the receiving device 20 of the first embodiment shown in Figure 3 in that it has a delay information transmitting unit 41 instead of the delay information transmitting unit 21.

Like the delay information transmission unit 21, the delay information transmission unit 41 calculates the reception delay time and transmits delay information representing the calculated reception delay information. Also, like the delay information transmission unit 21, the delay information transmission unit 41 is configured to periodically transmit delay information at predetermined time intervals. However, the delay information transmission unit 41 is configured to transmit delay information only to synchronization target devices, which are pre-designated devices among other receiving devices.

The synchronization target devices can be specified, for example, as follows: In other words, there is very little need to synchronize the execution times of processes between vehicle control ECUs that perform controls related to vehicle driving, such as brake control and accelerator control, and entertainment control ECUs that perform controls unrelated to vehicle driving, such as navigation device control, display device control, and audio control.

Taking the above into consideration, the ECUs in the vehicle control system are grouped together, and the ECUs in the entertainment control system are grouped together in another group. Then, for each of these groups, each ECU in the group can designate all of the other ECUs in that group as synchronization target devices, thereby enabling synchronization of the processing execution times of each ECU in the group. Note that there are also receiving devices in vehicles, such as ECUs that adjust power mirrors, that do not need to synchronize the processing execution times with other receiving devices. Such receiving devices can simply be left ungrouped.

Like the receiving device 20 of the first embodiment, the receiving device 40 configured as described above is configured to perform the first process, the second process, and the third process in parallel, but the content of the first process and the third process differs from that of the first embodiment. The content of the first process and the third process performed by the receiving device 40 of this embodiment will be described below with reference to Figures 12 and 13.

<Regarding the first process>
12, the first process of this embodiment differs from the first process of the first embodiment shown in FIG. 4 in that step S121 is added. In the first process of this embodiment, if step S101 returns "NO," that is, if the received data is not input data, the process proceeds to step S121. In step S121, it is determined whether the received data is other-device delay information transmitted from a synchronization target device.

Here, if the received data is not other device delay information sent from the device to be synchronized, that is, if the received data is other device delay information sent from a device other than the device to be synchronized, step S121 will be "NO" and the process will end without proceeding to step S102. On the other hand, if the received data is other device delay information sent from the device to be synchronized, step S121 will be "YES" and the process will proceed to step S102.

The first process of this embodiment can be modified to have the same content as the first process of the first embodiment shown in Figure 4, that is, to omit step S121. Even if modified in this way, no problems will arise as long as the delay information is transmitted only to the synchronization target device by executing the third process of this embodiment, which will be described later, in each receiving device 40.

However, for some reason, it is possible that delay information may be sent to a device other than the device to be synchronized. Even in such a case, according to the first process of this embodiment, step S121 is executed, and delay information sent from a device other than the device to be synchronized is discarded without being stored in the memory unit 22b, so there is no impact on the synchronization of the process execution time.

<Regarding the third process>
As shown in Fig. 13, the third process of this embodiment differs from the third process of the first embodiment shown in Fig. 6 in that step S324 is provided instead of step S304. In step S324, delay information indicating the reception delay time calculated in step S303 is transmitted only to the synchronization target device.

As explained above, the delay information transmission unit 41 of this embodiment is configured to transmit delay information only to synchronization target devices, which are pre-designated devices among other receiving devices. This configuration makes it possible to accommodate applications where the synchronization targets need to be limited, such as when it is sufficient to synchronize the processing execution times only between specific receiving devices 40, or when it is desired to group receiving devices 40 whose processing execution times should be synchronized.

(Fourth embodiment)
The fourth embodiment will be described below with reference to FIGS.
As shown in FIG. 14, a receiving device 50 of this embodiment differs from the receiving device 20 of the first embodiment shown in FIG. 3 in that it includes a data receiving unit 52 instead of the data receiving unit 22.

When the data receiving unit 52 receives data transmitted from the transmitting device 10, it adds the received data to the end of the buffer 22a even if the reception delay time calculated by the delay information transmitting unit 21 is equal to or greater than the maximum delay time of other devices. In other words, when the data receiving unit 52 receives data transmitted from the transmitting device 10, it always adds the received data to the end of the buffer 22a, regardless of whether the reception delay time calculated by the delay information transmitting unit 21 is equal to or greater than the maximum delay time of other devices.

The receiving device 50 configured as described above performs the first process, the second process, and the third process in parallel, similar to the receiving device 20 of the first embodiment, but the content of the first process differs from that of the first embodiment. The content of the first process performed by the receiving device 50 of this embodiment will be described below with reference to Figure 15.

<Regarding the first process>
As shown in Fig. 15, the first process of this embodiment differs from the first process of the first embodiment shown in Fig. 4 in that steps S103, S104, and S105 are omitted. In the first process of this embodiment, if step S101 is "YES," that is, if the received data is input data, the process proceeds to step S106, where the currently received input data is added to the end of the queue.

As explained above, when the data receiving unit 52 of this embodiment receives data transmitted from the transmitting device 10, it always adds the received data to the end of the buffer 22a, regardless of whether the reception delay time calculated by the delay information transmitting unit 21 is equal to or greater than the maximum delay time of other devices. This configuration provides the following effects. That is, in the first process, if the reception delay time Ta of the data receiving unit 22 of the first embodiment is equal to or greater than the maximum delay time Tb of other devices, it immediately uses the currently received input data without adding it to a queue.

In this configuration, if data is already stored in the queue at that time and the reception delay time Tc of the data stored at the top of the queue is equal to or greater than the maximum delay time Tb of other devices, the data stored at the top of the queue will be retrieved and used in the second process at the same time as the input data used in the first process described above. This means that the currently received input data and previous data stored in the queue will be used in parallel, and the chronological order of the data will no longer be guaranteed.

This situation can occur when the reception delay time of the device itself changes from a time less than the maximum delay time of the other device to a time greater than or equal to the maximum delay time of the other device, for example, if the maximum delay time of the other device decreases significantly for some reason. According to this embodiment, the input data received this time is not used as is without being added to the queue, and the data stored at the top of the queue is always used, so the problem of the chronological order of the data being used is not swapped.

(Other embodiments)
The present invention is not limited to the embodiments described above and illustrated in the drawings, but can be arbitrarily modified, combined, or expanded without departing from the spirit of the invention.
The numerical values and the like shown in the above embodiments are examples and are not limited to these.
The present invention is not limited to the network 1 described in each of the above embodiments, but can be applied to any vehicular network in which multiple communication devices mounted on a vehicle are connected via communication lines.

While the present disclosure has been described with reference to exemplary embodiments, it is understood that the present disclosure is not limited to those embodiments or structures. The present disclosure also encompasses various modifications and variations within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

The control unit and method described in this disclosure may be implemented by a special-purpose computer provided by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and method described in this disclosure may be implemented by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and method described in this disclosure may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible recording medium.

1...Network, 2...Camera, 3...LiDAR, 4...Preprocessing ECU, 5...Sub-ECU, 6...Control ECU, 7...Control ECU, 8...Communication line, 10...Transmitter, 11...Data transmitter, 20...Receiver, 21...Delay information transmitter, 22...Data receiver, 30...Receiver, 31...Delay information transmitter, 32...Data receiver, 40...Receiver, 41...Delay information transmitter, 50...Receiver, 52...Data receiver.

Claims (6)

In a vehicle network in which a plurality of communication devices (2 to 7) mounted on a vehicle are connected via a communication line (8),
each of the plurality of communication devices is configured to be able to synchronize time with another;
Among the plurality of communication devices, the communication devices that transmit specific data via the communication line are designated as transmitting devices (2, 3, 10), and the communication devices that receive and use the specific data via the communication line are designated as receiving devices (6, 7, 20, 30, 40, 50).
The transmitting device includes a data transmitting unit (11) that transmits the specific data after adding transmission information indicating a transmission time that is a time when the specific data was acquired or a time when the specific data is to be transmitted,
The receiving device
a delay information transmitting unit (21, 31, 41) that calculates a reception delay time, which is the difference between the transmission time indicated by the transmission information added to the received specific data and the reception time, which is the time when the specific data is received, and transmits delay information indicating the calculated reception delay time to another receiving device that is another receiving device;
a data receiving unit (22, 32, 52) for receiving and using the specific data transmitted from the transmitting device, the data receiving unit having a buffer (22a) with a queue structure capable of storing the specific data;
Equipped with
The data receiving unit
When receiving the specific data transmitted from the transmitting device, if the reception delay time calculated by the delay information transmitting unit is less than a maximum other device delay time, which is the longest time among the reception delay times represented by the delay information received from the other receiving devices, the received specific data is added to the end of the buffer, and if the reception delay time calculated by the delay information transmitting unit is equal to or greater than the maximum other device delay time, the received specific data is used without being added to the buffer;
A vehicle network that extracts and uses the specific data stored at the beginning of the buffer when the difference between the transmission time indicated by the transmission information assigned to the specific data stored at the beginning of the buffer and the current time becomes equal to or greater than the maximum delay time of the other device. The vehicle network described in claim 1, wherein the delay information transmission unit (21) transmits the delay information periodically at predetermined time intervals. The vehicle network described in claim 1, wherein the delay information transmission unit (31) transmits the delay information upon receiving a change notification indicating that there has been a change in the configuration of at least one of the plurality of communication devices and the communication lines. A vehicle network as described in any one of claims 1 to 3, wherein the delay information transmission unit (41) transmits delay information representing the reception delay time only to a pre-designated device among the other receiving devices. A vehicle network according to any one of claims 1 to 3, wherein the delay information transmission unit (21, 31) transmits delay information representing the reception delay time to all of the other receiving devices. 4. The vehicle network according to claim 1, wherein when the data receiving unit (52) receives the specific data transmitted from the transmitting device, if the reception delay time calculated by the delay information transmitting unit is equal to or longer than the maximum delay time of the other device , instead of using the received specific data without adding it to the buffer, the data receiving unit (52) adds the received specific data to the end of the buffer.