JP2022175848A - Control unit, communication system, and control method - Google Patents

Abstract

To prevent buffer overflow while considering the maximum value of allowable communication delay.SOLUTION: A plurality of electronic control units having buffers with a predetermined size include: a packet information storing part for storing reception schedule information including timing to receive a packet, allowable latency, and the length of burst; a peak prediction part for predicting peak time at which a buffer usage amount exceeds a predetermined value; a delay packet selection part for selecting a packet subject to delay which is a packet to be delayed for reception from packets whose reception is scheduled at the peak time estimated by the peak prediction part, based on the reception schedule information; a delay time determination part for determining delay time, which is the time of delay for the reception of delay subject packet selected by the delay packet selection part, to a value equal to or less than the allowable latency; and a delay signal generation part for transmitting a delay signal, which is a command for delaying transmission of the delay subject packet for the delay time, to an electronic control unit for transmitting the delay subject packet.SELECTED DRAWING: Figure 1

Description

The present invention relates to control devices, communication systems, and control methods.

In recent years, a configuration has been used in which a plurality of devices operate in cooperation with each other through communication. Communication relay devices that relay communications are known to have a problem of buffer overflow when multiple communications are concentrated in a short period of time. Patent Document 1 discloses a relay device that receives data from a communication device via a first communication path or a second communication path and transmits the received data, wherein the data received via the first communication path is a storage unit that stores data; a first transmission unit that transmits data stored in the storage unit; a deletion unit that deletes data transmitted by the first transmission unit from the storage unit; a data amount determination unit that determines whether or not the amount of data stored in the storage unit is equal to or greater than a threshold for data received via the a second transmission unit configured to transmit, to the communication device, instruction data instructing suspension of transmission via the first communication path and transmission via the second communication path when it is determined that A relay device is disclosed.

JP 2020-039033 A

The invention described in Patent Document 1 does not take into account the maximum allowable communication delay. Especially in automotive and industrial networks, it is essential to balance packet loss and communication delay because communication delay affects system soundness.

A control device according to the first aspect of the present invention sets, for each packet, a packet receiving timing, an allowable latency, and a burst length for a plurality of electronic control devices communicating via a communication relay device having a buffer of a predetermined size. a packet information holding unit for storing reception schedule information including information; a peak prediction unit for estimating a peak time when the usage of the buffer exceeds a predetermined value based on the reception schedule information; a delay packet selection unit that selects a delay target packet, which is a packet whose reception is to be delayed, from packets scheduled to be received at the peak time estimated by the peak prediction unit; and the delay target packet selected by the delay packet selection unit. a delay time determination unit for determining a delay time, which is a time for delaying reception of a packet, to a value equal to or less than the allowable latency; and a delay signal generator that transmits a delay signal that is a command to delay the transmission of the .
A communication system according to a second aspect of the present invention is a communication system including a control device and an arithmetic device, wherein the arithmetic device is for a plurality of electronic control devices communicating via a communication relay device having a buffer of a predetermined size. a storage unit for storing reception schedule information including packet reception timing, allowable latency, and burst length; and a peak prediction for estimating a peak time at which the buffer usage exceeds a predetermined value based on the reception schedule information. a delay packet selection unit that selects a delay target packet, which is a packet whose reception should be delayed, from packets scheduled to be received at the peak time estimated by the peak prediction unit based on the reception schedule information; a delay time determination unit that determines a delay time that is a time for delaying reception of the delay target packet selected by the packet selection unit, and the control device determines the calculation result of the delay packet selection unit and the delay time determination unit. a delay signal generation unit that transmits a delay signal, which is a command to delay transmission of the delay target packet by the delay time, to the electronic control device that transmits the delay target packet based on the above.
A control method according to a third aspect of the present invention includes reception schedule information including packet reception timing, allowable latency, and burst length for a plurality of electronic control units communicating via a communication relay device having a buffer of a predetermined size. a peak prediction step of estimating a peak time at which the buffer usage exceeds a predetermined value based on the reception schedule information; and the reception schedule information a delay packet selection step of selecting a delay target packet, which is a packet whose reception should be delayed, from the packets scheduled to be received at the peak time estimated in the peak prediction step, and the delay packet selection step selects based on a delay time determination step of determining a delay time, which is a time for delaying reception of the delay target packet; and delaying transmission of the delay target packet by the delay time with respect to the electronic control unit that transmits the delay target packet. and a delayed signal generation step of transmitting a delayed signal that is a command.

According to the present invention, it is possible to prevent buffer overflow while considering the maximum allowable communication delay.

FIG. 1 is an overall configuration diagram of a communication system according to a first embodiment; A diagram showing information stored in the packet information holding unit Flowchart showing the operation of the control device 1 FIG. 11 is a diagram showing temporal changes in the buffer before applying the processing according to the present embodiment; FIG. 10 is a diagram showing temporal changes in the buffer after applying the processing according to the present embodiment; Overall Configuration Diagram of Communication System in Second Embodiment Overall Configuration Diagram of Communication System in Third Embodiment Overall Configuration Diagram of Communication System in Sixth Embodiment Overall configuration diagram of a communication system in the seventh embodiment Flowchart showing the operation of the control device in the seventh embodiment

-First Embodiment-
A first embodiment of the control device will be described below with reference to FIGS. 1 to 5. FIG.

FIG. 1 is an overall configuration diagram of a communication system S including a control device 1. As shown in FIG. The communication system S includes a control device 1 , a switch 2 , a first device 31 and a second device 32 . The switch 2 is a network switch that transfers data between networks or between devices, and is also called a "communication relay device". In this embodiment, the data that the first device 31 and the second device 32 transmit to the switch 2 are called "packets". However, this name has no special meaning and may be called "frame", "segment" or "datagram".

In this embodiment, the switch 2 mainly transfers packets between the first device 31 and the second device 32, but the number of devices to be transferred may be three or more, and a network may be connected. . The first device 31, the second device 32 and the control device 1 are electronic control units. The communication standard used by the communication system S is not particularly limited, and IEEE802.3, CAN (registered trademark), LIN (Local Interconnect Network), and the like can be used.

The switch 2 includes a buffer unit 21 that temporarily stores received packets, and a transfer control unit (not shown) that transmits received packets to another device or network. Since the operation of the transfer control unit is well known, it will not be described in this embodiment. The buffer unit 21 is a storage area having a predetermined capacity and stores received packets. There is a limit to the capacity of the buffer unit 21, and if the reception is concentrated in a short period of time, there arises a problem that the received packets cannot be stored in the buffer unit 21. FIG. In order to avoid this problem, the control device 1 performs processing described later.

The first device 31 and the second device 32 perform predetermined unique processing and transmit the processing result via the switch 2 at predetermined intervals. Since the contents of the unique processing executed by the first device 31 and the second device 32 are not particularly limited, they will not be particularly described in the present embodiment.

The first device 31 includes a first device transmission/reception section 311 and a first delay control section 312 . The first device transmission/reception unit 311 is a communication port, and transmits information generated by the unique processing of the first device 31 . Also, when receiving a command from the control device 1 , the first device transmission/reception unit 311 transmits the command to the first delay control unit 312 . The first delay control section 312 delays the timing of transmission by the first device transmission/reception section 311 based on the command from the control device 1 .

The second device 32 includes a second device transmission/reception section 321 and a second delay control section 322 . The second device transmission/reception unit 321 is a communication port and transmits information generated by the second device 32 through unique processing. Also, when receiving a command from the control device 1 , the second device transmission/reception unit 321 transmits the command to the second delay control unit 322 . The second delay control section 322 delays the timing of transmission by the second device transmission/reception section 321 based on the command from the control device 1 .

The control device 1 includes a control device transmission/reception unit 11, a delay signal generation unit 12, a calculation result storage unit 13, a delay time determination unit 14, a delay packet selection unit 15, a peak prediction unit 16, and a packet information storage unit. 17. The calculation result holding unit 13 is implemented by a nonvolatile storage device such as a flash memory. The packet information holding unit 17 is implemented by a RAM or nonvolatile storage device. Information to be described later may be stored in the packet information holding unit 17 in advance, or may be updated as appropriate.

A CPU, which is a central processing unit (not shown), includes a ROM, which is a read-only storage device (not shown), and a RAM, which is a readable and writable storage device, and the CPU expands the program stored in the ROM into the RAM and executes it By doing so, the control device transmission/reception unit 11, the delay signal generation unit 12, the delay time determination unit 14, the delay packet selection unit 15, and the peak prediction unit 16 may be realized. Also, these may be realized by FPGA (Field Programmable Gate Array), which is a rewritable logic circuit, or ASIC (Application Specific Integrated Circuit), which is an application-specific integrated circuit, instead of the combination of CPU, ROM, and RAM. . Also, these may be realized by a combination of different configurations, for example, a combination of CPU, ROM, RAM and FPGA, instead of the combination of CPU, ROM, and RAM.

FIG. 2 is a diagram showing information stored in the packet information holding unit 17. As shown in FIG. A plurality of records are stored in the packet information holding unit 17 , and each record includes time 171 , source 172 , allowable latency 173 and burst length 174 . Time 171 is the time when the packet is scheduled to be received. Source 172 is the source of the packet. Acceptable Latency 173 is the maximum acceptable delay in communication. Burst length 174 is the size of the packet. For example, the first record shown in FIG. 2 indicates that a packet of 20 kB is scheduled to be received from the first device at time t1, and a maximum delay of 10 ms is allowed. The maximum allowable delay in these communications is determined by the application or the like. For example, data for an automatic driving system in an in-vehicle network is set with a strict delay allowance of about 10 ms or less.

The peak prediction unit 16 uses the packet information holding unit 17 to predict the peak time when the amount of usage of the buffer unit 21 exceeds a predetermined value. Therefore, for example, it may be predicted that the amount of use of the buffer unit 21 is always small and there is no peak time, or that multiple peak times are predicted.

The delay packet selection unit 15 selects packets whose reception by the switch 2 is to be delayed (hereinafter referred to as "delayed packets"). Specifically, the delay packet selection unit 15 selects a delay target packet from packets received at peak times. For example, the delay packet selection unit 15 selects, as a delay target packet, the packet with the maximum burst length among the packets received at the peak time. The delay packet selection unit 15 stores the information of the selected delay target packet, which is the calculation result, in the calculation result holding unit 13 . The delay time determination unit 14 determines the time for delaying reception of the delay target packet (hereinafter referred to as “delay time”). This delay time is at most the allowable latency value of the packet. For example, the delay time determination unit 14 sets the delay time to 80% of the allowable latency of the delay target packet. The delay time determination unit 14 stores information on the delay time, which is the calculation result, in the calculation result holding unit 13 .

Note that the delay packet selection unit 15 additionally selects a delay target packet when the amount of use of the buffer unit 21 still exceeds a predetermined value by delaying only one packet. For example, the delay packet selection unit 15 selects the packet having the second largest burst length among the packets received at the peak time as the second packet to be delayed. However, the delay packet selection unit 15 may select a packet received immediately before the peak time as a delay target packet.

The delay signal generation unit 12 sends a signal including a command to delay the transmission of the delay target packet by the delay time determined by the delay time determination unit 14 to the device that transmits the delay target packet selected by the delay packet selection unit 15. (hereinafter referred to as "delayed signal"). This delayed signal is transmitted to the switch 2 via the control device transmitting/receiving section 11, and then transmitted from the switch 2 to the target device. The delay signal generation unit 12 reads the information on the delay target packet and the information on the delay time from the calculation result holding unit 13 .

FIG. 3 is a flow chart showing the operation of the control device 1. As shown in FIG. The control device 1 executes the process shown in FIG. 3 at predetermined time intervals, each time the control device 1 is started, or when a predetermined number of days have passed since the previous execution. In step S<b>301 , the change detection unit 19 confirms a change in the configuration of software and hardware of each device that communicates using the switch 2 . In step S302, if the controller 1 determines that there is no change in the configuration as a result of the confirmation in step S301, the process proceeds to step S309, and if it is determined that there is a change in the configuration, the process proceeds to step S303.

In step S<b>303 , the control device 1 updates the packet information holding unit 17 . Specifically, the control device 1 may collect transmission packet information from each device connected to the switch 2, or may receive transmission packet information from the outside using a wireless communication device (not shown). good. In subsequent step S304, the peak prediction unit 16 refers to the packet information holding unit 17 and calculates the peak value of the usage amount of the buffer unit 21 and the peak time when the peak value is obtained. Specifically, the peak prediction unit 16 sets a period in which the capacity of the buffer unit 21 exceeds a predetermined threshold as a peak time, and calculates the maximum value of the usage amount of the buffer unit 21 for each peak time.

In subsequent step S305, the control device 1 determines whether or not the peak value calculated in step S304 exceeds the capacity of the buffer section 21 or not. If the controller 1 determines that the capacity will be exceeded, the process proceeds to step S306, and if it determines that the capacity will not be exceeded, the process proceeds to step S309. In step S306, the delay time determining unit 14 and the delayed packet selecting unit 15 refer to the packet information holding unit 17 to extract the time, allowable latency, and burst length of packets received at the peak time, and proceed to step S307.

In step S307, the delay time determination unit 14 and the delay packet selection unit 15 select a delay target packet, which is a packet to be delayed, and calculate the delay time for the delay target packet based on the information extracted in step S306. In the following step S308, the peak prediction unit 16 applies the calculation result in step S307, re-executes the calculation in step S304, and determines whether the peak value exceeds the capacity of the buffer unit 21 as in step S305. do. If the controller 1 determines that the capacity will be exceeded, the process returns to step S307, and if it determines that the capacity will not be exceeded, the process proceeds to step S309.

In step S309, the control device 1 shifts from the test mode to the operational mode. In subsequent step S310, the delay signal generation unit 12 generates and outputs a delay signal based on the calculation result in step S307 stored in the calculation result holding unit 13. FIG. In FIG. 3, step S310 is described as being executed only once, but in reality the generation and output of the delay signal are repeated at a predetermined cycle. The above is the description of FIG.

The effect of this embodiment will be visually described with reference to FIGS. 4 and 5. FIG. The two examples described here differ in packet transmission timing. FIG. 4 is a diagram showing temporal changes in the buffer before applying the processing in this embodiment. In FIG. 4, the transmission timings of the devices B and C match, and the amount of usage of the buffer unit 21 exceeds the threshold. Exceeding this threshold results in packet loss. In FIG. 5, a packet to be transmitted by device C is selected as a delay target packet, and a delay signal is output to device C from control device 1 . Therefore, the timing at which the device C outputs packets is later than in FIG. 4, and the amount of usage of the buffer unit 21 does not exceed the threshold. Therefore, no packet loss occurs in FIG.

According to the first embodiment described above, the following effects are obtained.
(1) The control device 1 controls the first device 31 and the second device 32 communicating via the switch 2 having the buffer section 21 of a predetermined size, for each packet, the time 171 which is the packet reception timing, the allowable latency 173 and burst length 174, and a peak prediction unit for estimating the peak time when the usage of the buffer unit 21 exceeds a predetermined value based on the reception schedule information. 16, a delay packet selection unit 15 that selects a delay target packet, which is a packet whose reception should be delayed, from the packets scheduled to be received at the peak time estimated by the peak prediction unit 16 based on the reception schedule information; A delay time determination unit 14 for determining a delay time, which is a time for delaying reception of the delay target packet selected by the unit 15, to a value equal to or less than the allowable latency, and an electronic control unit transmitting the delay target packet, for only the delay time and a delay signal generation unit 12 that transmits a delay signal that is an instruction to delay transmission of the delay target packet. Therefore, it is possible to prevent the buffer from overflowing while considering the maximum allowable communication delay. For example, software update or hardware replacement may increase the packet size or change the communication timing. If no countermeasures are taken, packet loss will occur as shown in FIG. Packet loss can be suppressed by the technique of morphology.

(2) The control device 1 includes a calculation result holding unit 13 that is a nonvolatile storage area. The delay packet selection unit 15 stores information on the selected delay target packet in the calculation result holding unit 13 . The delay time determination unit 14 stores information on the determined delay time in the calculation result holding unit 13 . The delay signal generation unit 12 creates and transmits a delay signal based on the information stored in the calculation result holding unit 13 . Therefore, the number of calculations of the delay time determination unit 14 and the delay packet selection unit 15 can be reduced.

(3) The control device 1 includes a change detection section 19 that detects changes in at least one of hardware and software in any one of the plurality of electronic control devices. The delay packet selection unit 15 and the delay time determination unit 14 perform calculation again when the change detection unit 19 detects a change, and store the calculation result in the calculation result holding unit 13 . Therefore, when the hardware and software are changed and there is a possibility that the amount of usage of the buffer unit 21 will change, the delay packet selection unit 15 and the delay time determination unit 14 perform calculations again, and the calculation result holding unit 13 Stored information can be updated.

(Modification 1)
Functions included in the control device 1 may be incorporated in the switch 2 . In other words, the control device 1 and the switch 2 may be configured as an integrated device.

(Modification 2)
The packet information holding unit 17 contains priority information for each packet, and the delay time determination unit 14 and the delay packet selection unit 15 use the priority information to select the delay target packet and determine the delay time. good too. This priority information is set by an operator, for example. For example, the delay time determining unit 14 sets a short delay time for packets with high priority and a long delay time for packets with low priority. The delay packet selection unit 15 also makes it more difficult for a packet with a higher priority to be selected as a delay target packet.

Furthermore, instead of setting the priority directly, the correspondence between the packet type and the priority may be defined. In this case, the control device 1 can identify the priority of the packet by determining the type of packet and referring to the correspondence between the type of packet and the priority.

According to Modification 2, the following effects are obtained.
(4) The reception schedule information further includes priority information for each packet. The delay packet selection unit 15 makes a packet with a higher priority less likely to be selected as a delay target packet. The delay time determining unit 14 sets a shorter delay time for a packet with a higher priority. Therefore, by setting high priority to packets that cannot be delayed, the operator can specify whether or not there is a delay for each packet.

(Modification 3)
The control device 1 does not have to include the calculation result holding unit 13 . In this case, in the control device 1, the peak predicting unit 16, the delayed packet selecting unit 15, and the delay time determining unit 14 perform calculations each time in order to generate the delay signal.

-Second Embodiment-
A second embodiment of the control device will be described with reference to FIG. In the following description, the same components as those in the first embodiment are assigned the same reference numerals, and differences are mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment mainly differs from the first embodiment in that the amount of usage of the buffer unit 21 is monitored.

FIG. 6 is an overall configuration diagram of a communication system S2 in the second embodiment. However, in FIG. 6, the description of the first device 31 and the second device 32 is omitted for convenience of drawing. The communication system S2 differs from the communication system S1 in the first embodiment in that the control device 1B further includes a buffer monitoring section 18 and the switch 2 further includes a buffer information output section 22. FIG.

The buffer information output unit 22 monitors the amount of usage of the buffer unit 21 and outputs information on the latest usage amount to the buffer monitoring unit 18 . The buffer monitoring unit 18 monitors the amount of use of the buffer unit 21 by reading information received from the buffer information output unit 22, and identifies peak times when the amount of use of the buffer unit 21 exceeds a predetermined value. The buffer monitoring unit 18 then compares the prediction by the peak prediction unit 16 with the peak time specified by the buffer monitoring unit 18 . When the buffer monitoring unit 18 determines that the peak time predicted by the peak prediction unit 16 is different from the peak time specified by the buffer monitoring unit 18 based on the output of the buffer information output unit 22, the peak time shown in FIG. Start test mode processing. In this case, a negative determination may always be made in step S302 and the process may proceed to step S303.

According to the second embodiment described above, the following effects are obtained.
(5) The control device 1B includes a buffer monitoring unit 18 that monitors the amount of buffer usage and identifies peak times when the amount of buffer usage exceeds a predetermined value. If the peak time estimated by the peak prediction unit 16 and the peak time specified by the buffer monitoring unit 18 are different, the reception schedule information is newly acquired. Therefore, the control device 1B can cope with unexpected changes in the communication state.

(Modification of Second Embodiment)
Instead of using the peak predictor 16 to predict peaks, the output of the buffer monitor 18 in test mode may be used. In this case, the buffer overflow can be reliably prevented because the actual measured value is used instead of the predicted value.

-Third Embodiment-
A third embodiment of the control device will be described with reference to FIG. In the following description, the same components as those in the first embodiment are assigned the same reference numerals, and differences are mainly described. Points that are not particularly described are the same as those in the first embodiment. The present embodiment differs from the first embodiment mainly in that generation of the delay signal and determination of the delay time are performed by different devices.

FIG. 7 is a configuration diagram of the communication system S3 in the third embodiment. However, in FIG. 7, the description of the first device 31 and the second device 32 is omitted for convenience of drawing. The communication system S3 is different in that the functions of the control device 1 in the first embodiment are divided into the control device 1C and the arithmetic device 4. FIG. The control device 1C and the arithmetic device 4 may be arranged close to each other or may be arranged at separate positions. For example, control device 1C and arithmetic device 4 may be arranged in the same vehicle. Further, for example, the control device 1C may be arranged inside the vehicle, and the arithmetic device 4 may be arranged outside the vehicle such as in a data center.

The control device 1C includes a control device transmission/reception section 11, a delay signal generation section 12, and a delay signal information holding section 17C. The control device transmitting/receiving section 11 is the same as in the first embodiment. The delay signal generator 12 generates a delay signal using the information stored in the delay signal information holding unit 17C. That is, the packet information holding unit 17 stores the same kind of information as the information output by the delay time determining unit 14 and the delayed packet selecting unit 15 in the first embodiment.

The arithmetic unit 4 includes a delay time determination unit 44, a delay packet selection unit 45, a peak prediction unit 46, a packet information storage unit 47, a change detection unit 49, and a delay signal information storage unit 47C. The delay time determining unit 44, the delayed packet selecting unit 45, the peak predicting unit 46, the packet information holding unit 47, and the change detecting unit 49 are similar to the delay time determining unit 14, the delayed packet selecting unit 15, the peak They correspond to the prediction unit 16, the packet information holding unit 17, and the change detection unit 19, respectively. The difference is that the delay time determination unit 44 and the delay packet selection unit 45 store the calculation results in the delay signal information holding unit 47C.

Information stored in the delay signal information holding unit 47C of the arithmetic device 4 is copied to the delay signal information holding unit 17C of the control device 1C by communication or other means. In the case of communication, a communication device (not shown) may be used, and each time the delayed signal information holding unit 47C is updated, it may be automatically copied to the delayed signal information holding unit 17C, or an operator may manually copy the information. good too. Alternatively, the information in the delay signal information holding unit 47C may be copied from the arithmetic device 4 to the control device 1C using a storage medium (not shown).

According to the third embodiment described above, the following effects are obtained.
(6) Communication system S3 includes control device 1C and arithmetic device 4 . Arithmetic device 4 performs packet reception timing 171, allowable latency 173, and A packet information holding unit 17 for storing reception schedule information including information on the burst length 174; a peak prediction unit 16 for estimating a peak time when the usage of the buffer unit 21 exceeds a predetermined value based on the reception schedule information; A delay packet selection unit 15 that selects a delay target packet, which is a packet whose reception should be delayed, from packets scheduled to be received at a peak time estimated by a peak prediction unit 16 based on reception schedule information, and a delay packet selection unit 15. A delay time determining unit 14 for determining a delay time, which is a time for delaying reception of the selected delay target packet, to a value equal to or less than the allowable latency. A delay signal generation unit 12 that transmits a delay signal, which is a command to delay transmission of the delay target packet by the delay time, to the electronic control device that transmits the delay target packet. Based on the calculation results of the delay signal generation unit 12 and the delay time determination unit 14, the control device 1C sends a delay signal, which is a command to delay the transmission of the delay target packet by the delay time, to the electronic control device that transmits the delay packet. A delay signal generator 12 for transmission is provided. Therefore, it is possible to prevent the buffer from overflowing while considering the maximum allowable communication delay.

-Fourth Embodiment-
A fourth embodiment of the control device will be described. In the following description, the same components as those in the first embodiment are assigned the same reference numerals, and differences are mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment differs from the first embodiment mainly in that it uses a pause frame.

In this embodiment, the communication standard used by the communication system is limited to IEEE802.3. In this embodiment, the delay signal generator 12 of the control device 1 uses a pause frame defined in IEEE802.3x. All of the switch 2, the first device 31, and the second device 32 support IEEE802.3 and IEEE802.3x. In this case, the delay signal generation unit 12 writes the address of the destination device in the destination address of the pause frame, so that the switch 2 performs transfer processing without discarding the pause frame.

According to the fourth embodiment described above, the following effects are obtained.
(7) The delay signal generator 12 uses the pause frame in IEEE802.3x for the delay signal. Therefore, the present invention can be easily implemented using existing standards.

- Fifth Embodiment -
A fifth embodiment of the control device will be described. In the following description, the same components as those in the first embodiment are assigned the same reference numerals, and differences are mainly described. Points that are not particularly described are the same as those in the first embodiment. The present embodiment is different from the first embodiment mainly in that the control device 1 instructs to stop and restart packet transmission one by one.

In this embodiment, the delay signal generator 12 generates and transmits two types of delay signals, ie, a delay start signal and a delay end signal. The difference between the delay signal in the first embodiment and the delay start signal in this embodiment is that the delay time is infinitely changed. The end of delay signal has the delay time set to zero. The delay signal generator 12 outputs a delay start signal before the packet to be delayed is transmitted, and outputs a delay end signal just before the timing at which the packet to be delayed is to be transmitted.

The first device 31 or the second device 32 that has received the delay start signal does not transmit packets until it receives the delay end signal. That is, in the first embodiment, the first device 31 or the second device 32 manages the time for delaying transmission, but in the present embodiment, the control device 1 manages the time. In this embodiment, since the control device 1 manages the delay time, there is an advantage that the accuracy of the time is improved when the accuracy of the timer in the first device 31 or the second device 32 is low.

According to the fifth embodiment described above, the following effects are obtained.
(8) The delay signal includes a delay start signal that suspends transmission of the delay target packet and a delay end signal that resumes transmission of the delay target packet. The delay signal generation unit 12 transmits a delay start signal to the electronic control unit that transmits the delay target packet before the delay target packet is transmitted, and waits for the delay time from the time when the delay target packet is scheduled to be transmitted. Send a delay end signal after the elapse. Therefore, when the precision of the timer in the first device 31 or the second device 32 is low, the timer in the control device 1 can be used to improve the time precision.

-Sixth Embodiment-
A sixth embodiment of the control device will be described with reference to FIG. In the following description, the same components as those in the first embodiment are assigned the same reference numerals, and differences are mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment differs from the first embodiment mainly in that part of the packet information is obtained by actual measurement.

FIG. 8 is an overall configuration diagram of a communication system S6 according to the sixth embodiment. However, in FIG. 8, the description of the first device 31 and the second device 32 is omitted for convenience of drawing. The communication system S6 further includes a packet information generator 19a in addition to the configuration of the first embodiment. The packet information generation unit 19 a acquires information on packets received by the switch 2 in the test mode, and acquires information on the time 171 , source 172 and burst length 174 in the packet information holding unit 17 .

For example, the switch 2 has a port mirroring function, and copies packets received by the ports connected to the first device 31 and the second device 32 to the ports connected to the control device 1 and outputs them. The packet information generator 19 a analyzes the received packet, acquires information on time 171 , source 172 , and burst length 174 , and writes the information to the packet information holder 17 . In this case, the value of allowable latency 173 may be a predetermined value, or only the value of allowable latency 173 may be obtained from the outside.

According to the sixth embodiment described above, the following effects are obtained.
(9) The control device 1F has a packet information generating section 19a that obtains information on packet reception timing and burst length by actual measurement and stores the information in the packet information holding section 17 as part of the reception schedule information. Therefore, it is possible to cope with changes in packet transmission timing.

-Seventh Embodiment-
A seventh embodiment of the control device will be described with reference to FIGS. In the following description, the same components as those in the first embodiment are assigned the same reference numerals, and differences are mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment differs from the first embodiment mainly in that the device to be connected is identified to determine whether the test mode is necessary.

FIG. 9 is an overall configuration diagram of a communication system S7 in the seventh embodiment. However, in FIG. 9, the illustration of the first device 31 and the second device 32 is omitted for convenience of drawing. The control device 1G of the communication system S7 further includes a packet type determination section 19b and a packet type holding section 19c in addition to the configuration of the first embodiment.

The packet type determination unit 19b acquires information on the packet received by the switch 2 in the test mode and determines the type of the packet. The packet type holding unit 19c stores the packet type determined in the past by the packet type determination unit 19b for each port of the switch 2 or each network address. The packet type is the type of packet payload, such as image, distance information, and others. The image can be identified by using the characteristics of the header portion for each image format. The distance information can be discriminated using a feature such as, for example, 120 degrees of numerical information arranged in increments of 0.5 degrees. Note that the packet type determination unit 19b may incorporate a database for determining the packet type. The packet type determining unit 19b associates the determined packet type with the port or network address of the device that transmitted the packet, and records them in the packet type holding unit 19c.

FIG. 10 is a flow chart showing the operation of the control device 1G in the seventh embodiment. In FIG. 10, the same step numbers are given to the same processing as in the flowchart showing the operation of the control device 1 in the first embodiment shown in FIG. Further, steps S306 to S308 are shown in one block in FIG. 10 for convenience of drawing. The difference from the flowchart showing the operation of the control device 1 in the first embodiment shown in FIG. 3 is the following two points. The first point is that steps S301 and S302 are changed to steps S301A and S302A. The second point is that steps S302a and S302b are added immediately before step S303.

In step S301A, the change detection unit 19 confirms a change in the software configuration. In the following step S302A, if the control device 1 determines that there is a change in the software configuration, it proceeds to step S303, and if it determines that there is no change in the software configuration, it proceeds to step S302a.

In step S302a, the packet type determination unit 19b determines the packet type of the received packet. In subsequent step S302b, the packet type determination unit 19b refers to the packet type holding unit 19c and determines whether or not the packet type is the same as the one determined in the past. This identity determination is made for each port of the switch 2 or for each network address. If the packet type determination unit 19b determines that the packet types are the same, the process proceeds to step S309, and if it determines that the packet types are not the same, the process proceeds to step S303.

That is, in the first embodiment, the processing of steps S303 to S308 is executed when there is a change in the software or hardware configuration. , the processing of steps S303 to S308 is not executed.

According to the seventh embodiment described above, the following effects are obtained.
(10) A packet type holding unit 19c that stores the types of packets transmitted by a plurality of electronic control units, and a packet type determination unit 19b that determines the types of packets transmitted by the plurality of electronic control units. When the packet type determined by the packet type determination unit 19b and the packet type stored in the packet type holding unit 19c do not match, the delay packet selection unit 15 and the delay time determination unit 14 perform the calculation again, and obtain the calculation result. is stored in the calculation result holding unit 13 . Therefore, when the hardware is replaced with the same kind of hardware, the processing of steps S303 to S308 can be omitted.

-Eighth Embodiment-
An eighth embodiment of the control device will be described. In the following description, the same components as those in the first embodiment are assigned the same reference numerals, and differences are mainly described. Points that are not particularly described are the same as those in the first embodiment. The present embodiment differs from the first embodiment mainly in that the control device 1 secures a margin for a specific packet type when controlling the amount of used buffer.

For a special packet type whose data amount increases during network operation, the control device 1 grasps the maximum data amount of the packet in advance, and stores other packets so that the buffer overflow does not occur even if the data amount reaches the maximum. control. This increase during operation refers to, for example, a situation in which the amount of sensor data acquired in an in-vehicle network increases depending on the surrounding conditions, but the test mode cannot be entered because the vehicle is in operation. Also, the maximum data amount of this special packet type may be derived from past network logs or theoretical values.

In each of the embodiments and modifications described above, the configuration of the functional blocks is merely an example. Some functional configurations shown as separate functional blocks may be configured integrally, or a configuration represented by one functional block diagram may be divided into two or more functions. Further, a configuration may be adopted in which part of the functions of each functional block is provided in another functional block.

Each of the embodiments and modifications described above may be combined. Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

Reference Signs List 1: control device 2: switch 4: arithmetic device 11: control device transmission/reception unit 12: delay signal generation unit 14: delay time determination unit 15: delay packet selection unit 16: peak prediction unit 17: packet information holding unit 17C: delay signal Information storage unit 18 Buffer monitoring unit 19 Change detection unit 19a Packet information generation unit 19b Packet type determination unit 19c Packet type storage unit 44 Delay time determination unit 45 Delayed packet selection unit 46 Peak prediction unit 47 Packet information holding unit 47C...Delayed signal information holding unit 49...Change detection unit

Claims (11)

Packet information holding that stores reception schedule information including packet reception timing, allowable latency, and burst length information for each packet for a plurality of electronic control units that communicate via a communication relay device having a buffer of a predetermined size. Department and
a peak prediction unit for estimating a peak time at which the buffer usage exceeds a predetermined value based on the reception schedule information;
a delay packet selection unit that selects a delay target packet, which is a packet whose reception should be delayed, from packets scheduled to be received at the peak time estimated by the peak prediction unit based on the reception schedule information;
a delay time determination unit that determines a delay time, which is a time for delaying reception of the delay target packet selected by the delay packet selection unit, to a value equal to or less than the allowable latency;
and a delay signal generator that transmits a delay signal, which is a command to delay transmission of the delay target packet by the delay time, to the electronic control device that transmits the delay target packet. The control device according to claim 1,
The reception schedule information further includes priority information for each packet,
The delay packet selection unit makes it more difficult for the packet with the higher priority to be selected as the delay target packet,
The control device, wherein the delay time determining unit sets the delay time shorter for a packet having a higher priority. The control device according to claim 1,
further comprising a calculation result holding unit, which is a non-volatile storage area;
The delay packet selection unit stores information on the selected delay target packet in the calculation result holding unit;
The delay time determination unit stores information on the determined delay time in the calculation result holding unit;
The control device, wherein the delay signal generation section creates and transmits the delay signal based on the information stored in the calculation result holding section. In the control device according to claim 3,
further comprising a change detection unit that detects a change in at least one of hardware and software in any one of the plurality of electronic control units;
The control device, wherein the delay packet selection section and the delay time determination section perform calculation again when the change detection section detects a change, and store the calculation result in the calculation result holding section. The control device according to claim 1,
A buffer monitoring unit that monitors the usage of the buffer and specifies a peak time when the usage of the buffer exceeds the predetermined value,
The control device newly acquires the reception schedule information when the peak time estimated by the peak prediction unit and the peak time specified by the buffer monitoring unit are different. The control device according to claim 1,
The control device, wherein the delay signal generator uses a pause frame in IEEE802.3x for the delay signal. The control device according to claim 1,
The delay signal is composed of a delay start signal that suspends transmission of the delay target packet and a delay end signal that resumes transmission of the delay target packet,
The delay signal generation unit transmits the delay start signal to the electronic control unit that transmits the delay target packet before the delay target packet is transmitted, and transmits the delay target packet before the delay target packet is transmitted. A control device that transmits the delay end signal after the delay time has elapsed from the time. The control device according to claim 1,
The control device, further comprising: a packet information generation unit that acquires information on the timing of receiving the packet and the burst length by actual measurement, and stores the information in the packet information storage unit as part of the reception schedule information. In the control device according to claim 3,
a packet type holding unit that stores the types of packets transmitted by the plurality of electronic control units;
a packet type determination unit that determines types of packets transmitted by the plurality of electronic control units;
The delay packet selection unit and the delay time determination unit perform calculation again when the packet type determined by the packet type determination unit and the packet type stored in the packet type storage unit do not match, and obtain a calculation result. in the calculation result holding unit. A communication system including a control device and an arithmetic device,
The computing device is
a storage unit that stores reception schedule information including packet reception timing, allowable latency, and burst length for a plurality of electronic control units that communicate via a communication relay device having a buffer of a predetermined size;
a peak prediction unit for estimating a peak time at which the buffer usage exceeds a predetermined value based on the reception schedule information;
a delay packet selection unit that selects a delay target packet, which is a packet whose reception should be delayed, from packets scheduled to be received at the peak time estimated by the peak prediction unit based on the reception schedule information;
a delay time determination unit that determines a delay time that is a time for delaying reception of the delay target packet selected by the delay packet selection unit;
The control device is
A delay signal, which is a command to delay transmission of the delay target packet by the delay time, is sent to the electronic control unit that transmits the delay target packet based on the calculation results of the delay packet selection unit and the delay time determination unit. A communication system comprising: a delayed signal generator for transmitting. Executed by a computer having a packet information holding unit that stores reception schedule information including packet reception timing, allowable latency, and burst length for a plurality of electronic control units that communicate via a communication relay device having a buffer of a predetermined size In the control method to
a peak prediction step of estimating a peak time at which the buffer usage exceeds a predetermined value based on the reception schedule information;
a delay packet selection step of selecting a delay target packet, which is a packet whose reception is to be delayed, from the packets scheduled to be received at the peak time estimated in the peak prediction step, based on the reception schedule information;
a delay time determination step of determining a delay time that is a time for delaying reception of the delay target packet selected by the delay packet selection step;
and a delay signal generation step of transmitting a delay signal, which is a command to delay transmission of the delay target packet by the delay time, to the electronic control device that transmits the delay target packet.

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