JP2015149564A - On-vehicle communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle communication system that can prevent breakage of data while keeping the minimum data reliability even when transmission data are partially broken.SOLUTION: At a transmission side, a first application divides transmission data to be transmitted to a second application into plural parts at a transmission side, applies a checksum to each of the plural divided data and transmits the data to a reception side. At the reception side, the thus-transmitted plural divided data are received, and each of the checksums is checked to detect the breakage of each of the plural divided data. When breakage of any divided data is detected, past received divided data held at the reception side or divided data whose breakage is detected by using blank data are complemented, and then coupled to one another, and the coupled data are transmitted to the second application. When the data are complemented, the complemented data are transmitted together with data representing the complement to the second application.

Description

  The present invention relates to an in-vehicle communication system that transmits and receives data in real time.

  Conventionally, data to be transmitted on the transmission side is divided into transmission units, the divided transmission unit data is numbered and transmitted, and error checking is performed for each transmission unit data divided on the reception side. There is a known communication system that requests retransmission on the transmission side (for example, Patent Document 1). Thereby, the reliability of transmission data is securable.

JP 58-56200 A

  By the way, a control system application on an in-vehicle device (for example, an application on an ECU that performs automatic braking control for avoiding a collision with an obstacle) receives information from an in-vehicle sensor or the like via an in-vehicle network. Then, control is executed based on the information.

  However, when the communication system described in Patent Document 1 described above is applied as an in-vehicle network, a retransmission request is made if even a part of the received data is damaged, so information cannot be acquired in real time. There is a risk that appropriate control may not be executed. For example, when an obstacle ahead of a vehicle is detected based on image data from a stereo camera and collision avoidance braking control is performed, if a retransmission request is made based on a partial loss of image data received from the stereo camera, the next time There are cases where the vehicle further approaches an obstacle by the time the image data is received, and collision avoidance cannot be performed appropriately.

  In view of the above problems, an in-vehicle communication system capable of preventing data disconnection while maintaining a minimum data reliability even when transmission data is partially damaged is provided. For the purpose.

In order to achieve the above object, in one embodiment, an in-vehicle communication system includes:
An in-vehicle communication system for transmitting data from a first application on the transmission side to a second application on the reception side,
A data dividing unit that is provided on the transmission side and divides the data acquired from the first application into a plurality of pieces;
A checksum providing unit that is provided on the transmission side and adds a checksum to each of a plurality of divided data divided by the data dividing unit;
A first transmission unit that is provided on the transmission side and transmits a plurality of divided data to which the checksum is added by the checksum addition unit to the reception side;
A receiving means provided on the receiving side for receiving a plurality of divided data transmitted by the first transmitting means;
A data corruption detection unit that is provided on the receiving side and detects a corruption of each of the plurality of divided data by confirming a checksum of each of the plurality of divided data received by the reception unit;
A data combining unit that is provided on the receiving side and combines a plurality of pieces of divided data received by the receiving unit, and when the data corruption detecting unit detects any broken data, the receiving side Data combining means for complementing each of the divided data received in the past held in the above, or the divided data detected to be damaged by using blank data;
Provided on the receiving side, the data combined by the data combining means is transmitted to the second application, and when the complement is performed by the data combining means, data indicating that the complement has been performed. In addition, a second transmission means for transmitting to the second application is provided.

  According to the present embodiment, it is possible to provide an in-vehicle communication system capable of preventing data disconnection while maintaining minimum data reliability.

It is a conceptual diagram which shows an example of a structure of a vehicle-mounted communication system. It is a block diagram which shows the structure of the vehicle front monitoring apparatus containing the communication system between camera-ECU which is a specific application example of the vehicle-mounted communication system which concerns on this embodiment. The vehicle-mounted communication system according to the present embodiment when an error occurs in data received by the ECU application when images captured by the camera of the vehicle forward monitoring apparatus shown in FIG. 2 are sequentially transmitted from the camera application to the ECU application. It is a figure explaining the effect | action of.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

  FIG. 1A is a conceptual diagram showing an example of the configuration of the in-vehicle communication system 1. The in-vehicle communication system 1 includes an in-vehicle network 10, a first application 20, and a second application 30, and the first application 20 (transmission side) on an arbitrary in-vehicle device to the second application 30 (reception side). Send data. The first application 20 and the second application 30 may be applications on the same in-vehicle device or may be applications on different in-vehicle devices.

  The in-vehicle network 10 includes a communication middle layer 11A (transmission side), a communication middle layer 11B (reception side), a MAC / PHY layer 12A (transmission side), and a MAC / PHY layer 12B (reception side).

  In response to a request from the first application 20, the communication middle layer 11 </ b> A executes processing on data to be transmitted from the first application 20 to the second application 30.

  The MAC / PHY layer 12A transfers data processed by the communication middle layer 11A to the receiving side in response to a request from the communication middle layer 11A.

  The MAC / PHY layer 12B receives the data transferred from the MAC / PHY layer 12A in response to a request from the communication middle layer 11B.

  In response to a request from the second application 30, the communication middle layer 11 </ b> B performs processing on the data received by the MAC / PHY layer 12 </ b> B and transmits the processed data to the second application 30.

  Next, a specific data flow of the in-vehicle communication system 1 according to the present embodiment will be described with reference to FIG.

  Referring to FIG. 1A, the communication middle layer 11A divides the data D transmitted from the first application 20 into a plurality of pieces. In this example, the communication middle layer 11A divides the data D into three segments (divided data) Dd1, Dd2, and Dd3.

  Subsequently, the communication middle layer 11A provides checksums CS1, CS2, and CS3 for detecting data corruption to the segments Dd1, Dd2, and Dd3.

  Subsequently, the MAC / PHY layer 12A transfers the segments Dd1 to Dd3 to which the checksums CS1 to CS3 are assigned to the transmission side.

  Subsequently, the MAC / PHY layer 12B receives the segments Dd1 to Dd3 transferred from the MAC / PHY layer 12A.

  The transfer from the MAC / PHY layer 12A to the MAC / PHY layer 12B is performed through Ethernet (registered trademark) or the like.

  Subsequently, the communication middle layer 11B confirms the checksums CS1 to CS3 given to the segments Dd1 to Dd3 received by the MAC / PHY layer 12B. In this example, of the three segments Dd1 to Dd3, the segment Dd3 is damaged during transfer. Therefore, the communication middle layer 11B can detect the breakage of the segment Dd3 by confirming the checksum CS3. This damaged segment Dd3 is discarded.

  Subsequently, the communication middle layer 11B combines the received segments Dd1 to Dd3 to reconstruct data. In this example, since the segment Dd3 is damaged, data is reconstructed using the replacement segment Drep instead of the segment Dd3. That is, the segments Dd1 and Dd2 and the replacement segment Drep are combined to reconstruct the combined data Dcomb. As the replacement segment Drep, a segment (divided data) corresponding to the segment Dd3 received by the MAC / PHY layer 12B immediately before may be used, and in some cases, a blank segment (blank data) may be used. If none of the segments Dd1 to Dd3 is damaged, the segments Dd1 to Dd3 are combined to reconstruct data (generation of combined data Dcomb).

  The communication middle layer 11B transmits the combined data Dcomb partially supplemented by the replacement segment Drep to the second application 30. That is, the second application 30 receives the combined data Dcomb that is partially complemented with respect to the data D transmitted from the first application as the data transmitted from the first application 20. In addition, the combined data Dcomb transmits (notifies) information indicating that the data is partially complemented to the second application. For example, the information indicating that the partial complement has been performed may include information regarding the complemented area. When none of the segments Dd1 to Dd3 is damaged, the data D transmitted from the first application 20 and the combined data Dcomb received by the second application 30 are equivalent. In this case, the communication middle layer 11 </ b> B may or may not transmit information indicating that partial complement has not been performed to the second application.

  Here, the effect | action of the vehicle-mounted communication system 1 which concerns on this embodiment is demonstrated using the vehicle-mounted communication system 1c which concerns on the comparative example shown in FIG.1 (b).

  The in-vehicle communication system 1c according to the comparative example illustrated in FIG. 1B performs data communication from the first application 20 to the second application 30, as in the in-vehicle communication system 1 according to the present embodiment. . The difference from the present embodiment is the operation of the in-vehicle network 10c that performs data communication, particularly the operation of the communication middle layer 11Ac (transmission side) and 11Bc (reception side).

  Specifically, before the communication middle layer 11Ac divides the data D transmitted from the first application 20 into a plurality of pieces, the checksum CS is given, and the data D with the checksum CS is assigned to the segments Dd1 to Dd3. To divide. Further, the communication middle layer 11Bc combines the segments Dd1 to Dd3 received by the MAC / PHY layer 12B and confirms the checksum CS. Therefore, when the segment Dd3 is damaged as shown in FIG. 1B, a part of the combined data Dcomb is missing, and the checksum CS is confirmed to detect the entire combined data Dcomb. The combined data Dcomb that is damaged is discarded as a whole. When the combined data that has been damaged is discarded as a whole, the second application 30 cannot receive the data. For example, data is periodically transmitted from the first application 20 to the second application 30. In this case, one period of data is lost. In particular, when acquiring information such as sensors mounted on the vehicle in real time as in a vehicle control system application and executing control, there is a possibility that information cannot be acquired in real time and appropriate control cannot be performed.

  On the other hand, as described above, the in-vehicle communication system 1 according to the present embodiment is provided with a checksum for each divided data, and thus can perform a damage check for each divided data. Therefore, even if a part of the divided data (segment Dd3) is damaged, the past divided data (for example, the previously acquired divided data) is received by the damaged segment (divided data). Data) or blank data. Then, by performing partial complementation and transmitting the combined data to the second application 30, the second application 30 has a part in which the data transmitted from the first application 20 is partially supplemented. It can be obtained in real time without interruption. In addition, since the data partially supplemented and combined includes information of data transmitted from the first application 20 except for the supplemented part, the second application 30 is based on the information. Control can be continued.

  In addition, since the in-vehicle communication system 1 according to the present embodiment notifies the second application 30 that the supplement has been performed, the second application 30 considers that the received data is the supplemented data. The minimum data reliability can be secured by performing control. That is, even when transmission data is partially damaged, data disconnection can be prevented while maintaining minimum data reliability. For example, in the data, the in-vehicle communication system 1 (communication middle layer 11B) notifies the second application 30 of information on the supplemented area, so that the second application 30 is based on information other than the supplemented area. Control can be performed.

  Next, a specific application example of the in-vehicle communication system 1 according to the present embodiment will be described.

  FIG. 2 is a configuration diagram showing a configuration of a vehicle front monitoring apparatus 100 including a camera-ECU communication system (hereinafter simply referred to as a communication system) 101 which is a specific application example of the in-vehicle communication system 1 according to the present embodiment. It is.

  The vehicle front monitoring apparatus 100 includes a communication system 101, a camera 110, an ECU 120, a CAN (Controller Area Network) 130, and the like, and monitors obstacles ahead of the vehicle based on images captured by the camera 110. For example, the ECU 120 detects an obstacle ahead of the vehicle based on an image captured by the camera 110, and performs a collision determination between the own vehicle and the obstacle based on the calculated distance between the own vehicle and the obstacle. When it is determined that the possibility of a collision is high, a control command is output to the brake actuator of the host vehicle in order to generate a braking force due to intervention for avoiding the collision.

  The camera 110 is an imaging unit that is mounted at the front end of the vehicle and images the front of the vehicle. The camera 110 is communicably connected to the ECU 120, and a control application (hereinafter referred to as a camera application) on the camera 110 (internal control unit) generates an image signal corresponding to the captured image. It is transmitted to the control application (hereinafter referred to as ECU application).

  The ECU 120 is an electronic control unit that performs vehicle forward monitoring control. Specifically, as described above, the ECU 120 detects an obstacle ahead of the vehicle based on an image received from the camera 110 (camera application), and the obstacle is detected. Collision avoidance control may be performed. The ECU 120 (ECU application) receives an image signal (image data) from the camera 110 (camera application) via the communication system 101.

  The CAN 130 is an in-vehicle network (LAN) for performing mutual communication between various ECUs and actuators. In this example, the ECU 120 may be connected to the CAN 130 and output a control command to a brake actuator (not shown) or the like via the CAN 130. The ECU 120 may output a control command to another ECU (brake ECU) that directly controls the brake actuator to execute a braking control for avoiding a collision, or directly output a control command to the brake actuator. Thus, the braking control for avoiding the collision may be executed.

  Next, FIG. 3 is used for the operation of the camera-ECU communication system 101 that is an application example of the in-vehicle communication system 1 according to the present embodiment, particularly, the operation when an error occurs during transfer on the communication system 101. I will explain.

  FIG. 3 is a diagram illustrating the operation of the communication system 101 when images (image data) are sequentially transmitted from the camera 110 (camera application) to the ECU 120 (ECU application). FIG. 3A is a diagram for explaining the operation of the communication system 101 to which the in-vehicle communication system 1 according to the present embodiment is applied, and FIG. 3B is an application of the in-vehicle communication system 1c according to the comparative example described above. It is a figure explaining operation | movement by the communication system which performed. FIGS. 3A and 3B show a state in which image data (images F1 to F5) transmitted from the camera application at intervals of 50 msec are sequentially received by the ECU application. In addition, an error (damage) occurs during transfer in the communication system 101 for the image F4 transmitted from the camera application.

  Referring to FIG. 3A, the communication system 101 to which the in-vehicle communication system 1 according to the present embodiment is applied, the image F4x that is divided and transmitted, and the image F4x including the damaged portion is immediately before the image F4x. Replacement (complementation) by data of a corresponding part (segment) of the image F3 is performed. That is, the image F4 is generated as an image complemented by past image data (the image F3 received immediately before). Therefore, it is possible to continue the control in real time without the data being interrupted and without being delayed at intervals of 50 msec. Further, as described above, since the communication system 101 notifies the ECU application of information indicating that the image F4 is complemented (image data), the ECU application performs control based on the image excluding the complemented portion. And the reliability of data can be ensured. In particular, in the complemented image F4 shown in the lower diagram of FIG. 3A, even if the damaged portion is replaced with a corresponding portion of the immediately preceding image F3, it is possible to recognize an obstacle (front vehicle) traveling ahead of the vehicle. Does not affect the reliability of the control by the ECU 120. That is, when a part of the divided data is damaged, the control process can be appropriately continued even if the damaged divided data is replaced with, for example, the immediately preceding corresponding divided data. The received image may be stored (held) in a RAM or the like in the ECU 120, and the above complement may be performed by using a past image (an image received immediately before) stored in the RAM or the like.

  On the other hand, referring to FIG. 3B, in the communication system to which the in-vehicle communication system 1c according to the comparative example is applied, when an error occurs during transfer, the image F4 in which the error has occurred is discarded. Therefore, since the ECU application cannot acquire image data for one cycle, there is a possibility that the vehicle front monitoring control cannot be appropriately executed for 100 msec. For example, to detect an obstacle 5 m ahead of the vehicle while the host vehicle is traveling at 40 km / h and avoid a collision with the obstacle, the level is several hundred msec from the detection of the obstacle to the control command (braking command). Processing with is required. Therefore, if a delay of 100 msec occurs in acquiring image data for detecting an obstacle, an appropriate braking control process is hindered.

  As described above, the communication system to which the in-vehicle communication system 1c according to the comparative example is applied causes a delay in the acquisition of the image data and hinders the control processing. Since data is complemented, there is no delay in data acquisition. Therefore, an obstacle ahead of the vehicle can be detected in real time, and control processing for avoiding appropriate collision can be continued.

  As mentioned above, although the form for implementing this invention was explained in full detail, this invention is not limited to this specific embodiment, In the range of the summary of this invention described in the claim, various Can be modified or changed.

DESCRIPTION OF SYMBOLS 1 In-vehicle communication system 10 In-vehicle network 11A Communication middle layer (data division means, checksum provision means)
11B Communication middle layer (data corruption detection means, data combination means, second transmission means)
12A MAC / PHY layer (first transmission means)
12B MAC / PHY layer (reception means)
20 First Application 30 Second Application 100 Vehicle Forward Monitoring Device 101 Camera-ECU Communication System 110 Camera 120 ECU
130 CAN

Claims (1)

An in-vehicle communication system for transmitting data from a first application on the transmission side to a second application on the reception side,
A data dividing unit that is provided on the transmission side and divides the data acquired from the first application into a plurality of pieces;
A checksum providing unit that is provided on the transmission side and adds a checksum to each of a plurality of divided data divided by the data dividing unit;
A first transmission unit that is provided on the transmission side and transmits a plurality of divided data to which the checksum is added by the checksum addition unit to the reception side;
A receiving means provided on the receiving side for receiving a plurality of divided data transmitted by the first transmitting means;
A data corruption detection unit that is provided on the receiving side and detects a corruption of each of the plurality of divided data by confirming a checksum of each of the plurality of divided data received by the reception unit;
A data combining unit that is provided on the receiving side and combines a plurality of pieces of divided data received by the receiving unit, and when the data corruption detecting unit detects any broken data, the receiving side Data combining means for complementing each of the divided data received in the past held in the above, or the divided data detected to be damaged by using blank data;
Provided on the receiving side, the data combined by the data combining means is transmitted to the second application, and when the complement is performed by the data combining means, data indicating that the complement has been performed. In addition, it comprises a second transmission means for transmitting to the second application.
In-vehicle communication system.

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