JP4709037B2 - In-vehicle database system - Google Patents

Description

  The present invention relates to an in-vehicle database system, and more particularly to an in-vehicle database system that optimizes communication by an in-vehicle LAN to lower a communication load factor and suppress a resource consumption rate of each unit.

  In recent years, with the increase in functions of automobiles, the number of electronic control units (ECUs) installed in automobiles tends to increase. Further, if each ECU is connected by a vehicle control network (hereinafter simply referred to as an in-vehicle LAN), the number of ECUs connected to the in-vehicle LAN increases and the amount of data to be communicated also increases. There is a limit to the amount of data that can be created. Therefore, the in-vehicle LAN to which the ECU is connected is divided to reduce the communication load factor in each divided in-vehicle LAN.

For example, as shown in FIG. 11, a plurality of ECUs 90a to 90c,.
ECU 90d, 90e... Are connected using another in-vehicle LAN bus 91b compliant with CAN, and both buses 91a, 91b are connected to gateway 92. Are connected so that various data can be communicated between the ECUs 90a to 90e.

  With the above configuration, the data Dpa indicating the measured value or state measured by the sensor 93a connected to one ECU 90a is output to the ECUs 90a to 90c in the bus 91a at intervals of 10 ms, for example, and this data Dpa is required. The ECU 90b can receive the data Dpa at intervals of 10 ms by appropriately receiving the data Dpa output to the bus 91a. On the other hand, since the data Dpa is relayed to the bus 91b by the gateway 92, the ECU 90e in the bus 91b can also receive the data Dpa.

In recent years, the amount of data communicated between the buses 91a and 91b tends to increase. Therefore, as the buses 91a and 91b, FlexRay (registered trademark), MOST (Media Oriented Systems Transport), D2B (Domestic Digital).
An in-vehicle LAN having sufficient traffic such as Bus) is used.

  For example, in an in-vehicle LAN conforming to FlexRay, as shown in FIG. 12, the communication timing is synchronized so that a collision does not occur even if the data amount increases. As shown in the figure, the ECUs 90a to 90c include FlexRay communication units 95a to 95c, respectively, and the FlexRay communication units 95a to 95c include transmission buffers 96a to 96c and reception buffers 97a to 97c, respectively. Each of the ECUs 94a to 94c prevents the occurrence of a collision by transmitting the data in the transmission buffers 96a to 96c to a FlexRay bus (not shown) at predetermined times m1 to m3 in the communication cycle. And transmission delay of data due to collision can be prevented.

  Further, in Japanese Patent Laid-Open No. 2005-159568 (Patent Document 1), when the transmission timing is delayed due to a transmission error or the like, it is possible to reliably transmit from a high-priority ID so that communication load is high for data with high priority. A configuration has been proposed in which a large delay does not occur even when the rate is increased.

  However, since the in-vehicle LAN has a multicast configuration, there is a problem that the resources of the ECUs 90a... Are consumed wastefully in order to temporarily receive all data Dpa to be communicated. That is, as shown in FIG. 13, even when the in-vehicle hubs 99 a to 99 c that perform high-speed communication using the in-vehicle LAN bus 98 that conforms to a standard such as FlexRay that enables high-speed communication between the ECUs 90 a to 90 f, the data Dpa. The in-vehicle hub connected to the ECU 90a that needs to relay the data Dpa that is expected to be necessary, and receives data Dpa that is unnecessary for most ECUs (or all ECUs depending on the timing) 90a. In order to do so, the resources of each ECU 90a. For this reason, it is necessary to make the resources of the ECUs 90a, 90b,... Sufficiently compatible with the increase in the amount of data to be communicated.

In addition, even when a bus that performs synchronous communication such as FlexRay as shown in FIG. 12 is used, task processing T11 to T34 for transmitting and receiving data via the communication means 95a to 95c is performed in each ECU 90a to 90c. Executed.
Due to a delay in the timer for managing the task processes T11 to T34, it may not be in time for the predetermined time points m1, m2,... In the communication cycle, and a delay may occur in data transmission.
For this reason, data to be transmitted is accumulated in the transmission buffers 96a to 96c, causing a delay in control using this data, which causes stress on the ECUs 90a to 90c. The occurrence of such stress becomes a problem as the number of logical connections between the ECUs 90a to 90c increases, and there is a concern that it becomes a problem as the performance of the automobile increases.

  Further, in the above-described conventional in-vehicle LAN constituting the multicast, even if the data Dpa required in the receiving ECU is sufficient at intervals of about 1 second, the transmitting ECU 90a transmits the data Dpa at intervals of 10 ms. In all related buses 91a, 91b, 98, data Dpa is transmitted at intervals of 10 ms. As a result, the communication load factor of the buses 91a, 91b, and 98 is increased, and as the communication load factor increases, there is a problem that the possibility of delay in data transmission increases with the occurrence of a collision.

JP 2005-159568 A

  The present invention has been made in view of the above problems, and efficiently uses an ECU with limited resources, transmits and receives necessary update data at high speed, hardly causes a delay due to transmission and reception delay, and is a communication load factor of an in-vehicle LAN. To provide a highly reliable in-vehicle database system.

To solve the above problems, the present invention includes an ECU which is plurality with divided into a plurality of groups each group,
An in-vehicle LAN having a database distribution node connected to the ECU in each group and provided one for each group; and a transmission line sequentially connecting the database distribution nodes provided for each of the plurality of groups;
Each of the database distribution nodes includes a processing unit having a database, ECU side transmission / reception means for transmitting / receiving data between the processing unit and the connected ECU, and update data recorded in the database of the processing unit. Inter-node transmission / reception means for transmitting / receiving to / from other database distribution nodes,
Each database distribution node and each ECU are connected via an in-vehicle LAN, and each ECU transmits update data from the connected sensor to the database distribution node and records it in the database,
The update data recorded in the database of the one database distribution node is sequentially circulated to the other database distribution nodes through the transmission path so that the other database distribution nodes can receive the update data. Update data from other database distribution nodes recorded in the database of the other database distribution node and shared in the database of the other database distribution node is sent to the ECU in accordance with the set timing or a transmission request from the ECU side. An in-vehicle database system characterized by being configured to transmit is provided.

  The ECUs are preferably grouped for each function, but ECUs arranged at close positions may be grouped together.

In the present invention, as described above, first, a large number of ECUs are divided into a plurality of groups, and a database distribution node including a database is provided for each group. Record the update data of ECUs in each group in a database, send the update data recorded in the database to other database distribution nodes, and record the necessary update data in the other database distribution nodes in that database The update data can be shared.
In this way, by dividing a large number of ECUs into a plurality of groups, the number of ECUs connected to one database distribution node can be reduced as compared with the case where all ECUs are connected by bus. Can send and receive update data at high speed and avoid collisions during transmission.

  Further, between the database distribution nodes provided for each group, only the update data recorded in the database distribution node is transmitted through the transmission path, thereby reducing the communication load factor and causing the collision. Transmission delay due to can be prevented. In addition, since the database distribution nodes are connected one after another in a one-to-one connection, update data can be exchanged between the nodes efficiently, and high-speed communication can be performed stably. Furthermore, since the other database distribution nodes fetch only necessary update data, an increase in the amount of data processing can be suppressed. Further, each database distribution node transmits update data acquired from other database distribution nodes to an ECU connected to the database distribution node at a required timing. Transmission is not delayed and the occurrence of control delay by the ECU can be prevented.

The transmission path between the database distribution nodes is configured such that adjacent database distribution nodes are connected in a daisy chain, one database distribution node connected in the daisy chain is used as a master node, and the other database distribution node is connected to the database distribution node. A loopback node,
In the forward path from the master node to the loopback node, the update data frame for writing the update data recorded in the database in each database distribution node is circulated, and in the return path from the loopback node to the master node, all the update data is stored. The written update data frame is circulated, and the update data required in each database distribution node is read to update the database.

By connecting each database distribution node in a ring shape by connecting the master node and the loopback node via an additional transmission line, when a failure occurs in the transmission line, The update data frame may be circulated between the master node and the loopback node, with the database distribution node on one side sandwiched as a master node and the database distribution node on the other side as a loopback node.
With this configuration, even when a failure occurs in the in-vehicle LAN, a new master node and loopback node can be defined, and the update data frame can be circulated between the master node and the loopback node. A highly reliable system can be realized.

Instead of the daisy chain connection, the transmission path between the database distribution nodes connects adjacent database distribution nodes in a ring shape,
One of the database distribution nodes connected in the ring shape is a master node,
Rotating the update data frame in one direction from the master node,
In the first round, the update data recorded in the recording means of each database distribution node is written in the update data frame,
In the second round, the database may be updated by reading the update data required in each database distribution node from the update data frame in which all update data is written.

In this case, when a failure occurs in the transmission path, the database distribution node on one side sandwiching the failure point is set as a master node, the database distribution node on the other side is defined as a loopback node, and the master node and the loopback node The update data frame may be circulated between and.
Normally, the update data frame circulates in one direction between the database distribution nodes. However, in the case of a transmission line failure, the update data frame is updated between the master node and the loopback node as in the case of daisy chain connection. A highly reliable system can be realized by circulating frames.

In the present invention, as described above, each database distribution node and each ECU are connected via an in-vehicle LAN, and each ECU continuously transmits update data from the connected sensor to the database distribution node. While being recorded in the database, update data from other database distribution nodes recorded in the database of the database distribution node is transmitted to the ECU in accordance with the set timing or a transmission request from the ECU side.
For example, the brake control ECU transmits a detected value (rpm) of the wheel speed detected by the connected wheel speed sensor to the connected ECU, and the received database distribution node records the received update data in the database. As described above, this update data is transmitted to the other database distribution node, and when the other database distribution node needs the detected value data of the wheel speed, the update data is acquired and recorded in the database. . The recorded update data is transmitted to the ECU connected to the database distribution node in response to a preset timing or a request from the ECU side.

A plurality of transmission paths connecting the database distribution nodes may be provided, and the same update data frame may be circulated in the same direction using the plurality of transmission paths.
Even if one update data frame cannot be transmitted due to the occurrence of a failure, the update data frame having the same content is circulated in the same direction using a plurality of transmission paths between the master node and the loopback node. The database can be updated using the frame, and a highly reliable system can be realized.

Furthermore, a configuration may be adopted in which a plurality of transmission paths connecting the database distribution nodes are provided, and a plurality of update data frames are circulated in the same direction using the plurality of transmission paths.
A plurality of update data frames having different contents can be circulated in the same direction using a plurality of transmission paths between the master node and the loopback node, thereby enabling higher-speed communication than using a single transmission path. .
Also, reliability is ensured by transmitting update data frames with the same contents to two or more of the multiple transmission paths and transmitting update data frames with different contents to the remaining transmission paths. High-speed communication can be performed.

Furthermore, a plurality of transmission paths that connect the database distribution nodes may be provided, and some of the transmission paths may transmit update data frames in the forward direction and the remaining transmission paths may transmit in the reverse direction.
Since transmission can be performed in both directions through a plurality of transmission paths, communication can be performed at a higher speed than transmission in only one direction.

As described above, according to the present invention, first, a large number of ECUs are divided into a plurality of groups, and a database distribution node having a recording means is provided for each group, and update data of ECUs in each group is recorded in the database. And the update data recorded on required ECU are transmitted as needed.
In this way, since the number of ECUs connected to the database distribution node can be reduced, update data can be transmitted and received at high speed, and collision during transmission can be avoided.

  In addition, between the database distribution nodes provided for each group, only the update data is transmitted through the transmission line, and the update data is shared between the database distribution nodes. Transmission delay due to the occurrence of. In addition, since the database distribution nodes are connected one after another in a one-to-one connection, update data can be exchanged between the nodes efficiently, and high-speed communication can be performed stably. Furthermore, since the other database distribution nodes fetch only necessary update data, the amount of data processing does not increase, transmission to the ECU through the database distribution node is not delayed, and the ECU Generation of control delay can be prevented.

  Further, when a failure occurs in a transmission line connected in a ring shape, the master node is a database distribution node on one side sandwiching the failure point, and the master node is a database distribution node on the other side. The update data frame is circulated between the network and the loopback node, so that the update data frame can be circulated even when a failure occurs in the in-vehicle LAN, and a highly reliable system is realized. it can.

  An in-vehicle database system is more reliable than using a single transmission line if multiple transmission lines are connected between each database distribution node and the same update data frame is transmitted in the same direction using multiple transmission lines. Sex can be secured. In addition, when a plurality of update data frames are transmitted in the same direction using a plurality of transmission paths, higher-speed communication is possible than using a single transmission path. Furthermore, if a configuration is used in which update data frames are transmitted in opposite directions using a plurality of transmission paths, higher-speed communication is possible than transmission in one direction.

FIG. 1 is a diagram showing the configuration of an in-vehicle database system 1 according to the first embodiment of the present invention.
In FIG. 1, 2a to 2h are ECUs (hereinafter referred to as ECUs 2 when there is no need to distinguish between the ECUs 2a, 2b...) Arranged in each part of the vehicle, and 2a to 2c are first groups A, 2d to 2a. 2f is a second group B, 2g and 2h are grouped as a third group C.
Each of the groups A, B, and C has one database distribution node 4a, 4b, and 4c (hereinafter referred to as the database distribution node 4 when it is not necessary to distinguish each of the database distribution nodes 4a to 4c). Provided.
The database distribution node 4a is connected to the ECUs 2a to 2c by an in-vehicle LAN bus (hereinafter referred to as a CAN bus) 8 compliant with CAN. Similarly, the database distribution node 4b is connected to the ECUs 2d to 2f via the CAN bus 8, and the database distribution node 4c is connected to the ECUs 2g and 2h via the CAN bus 8, respectively.
The database distribution nodes 4a, 4b, and 4c are sequentially connected through transmission paths 5a, 5b, and 5c (hereinafter collectively referred to as transmission paths 5) that are configured as an in-vehicle LAN, and constitute an in-vehicle LAN 9.

  Sensors 6a to 6h for detecting update data Da to Dh such as vehicle state and measured values of various physical quantities and outputting them to the ECU are connected to the ECUs 2a to 2h. (Hereinafter, when there is no need to distinguish, they are simply referred to as sensor 6 and update data D.)

  Each database distribution node 4 is connected to a plurality of ECUs, and is connected to another database distribution node 4 via the transmission path 5 to transmit and receive various update data between the database distribution nodes and between the ECUs at high speed. It is supposed to act as a hub.

As shown in FIG. 1, each database distribution node 4 includes a processing unit 13, a CAN communication unit 11 that constitutes an ECU-side transmission / reception unit that transmits and receives update data between the processing unit 13 and the ECU 2, and a processing unit 13. Ethernet communication means 12 that constitutes an inter-node transmission / reception means for transmitting / receiving update data via the transmission path 5 to and from the processing section of another database distribution node 4, and the processing section 13 includes a database 7. Means 21, output timing setting means 22, data output means 23, and database update means 24 are provided.
The recording means 21 and the CAN communication means 11 are connected via the data output means 23 and the output timing setting means 22. The recording means 21 and the Ethernet communication means 12 are connected via a database update means 24.
In FIG. 1, the recording means 21 and the like are described only in the database distribution node 4a, but other database distribution nodes 4b and 4c are also provided.

In this embodiment, Ethernet (registered trademark) conforming to a standard capable of high-speed communication is used as the in-vehicle LAN 9 including the transmission paths 5a, 5b, and 5c connected to the ports 12a and 12b of the Ethernet communication unit 12.
Since the in-vehicle LAN 9 constitutes a single-segment in-vehicle LAN conforming to Ethernet, it is not necessary to intervene a gateway or the like, and the delay time can be shortened accordingly.
Note that the in-vehicle LAN 9 may be formed using a communication that complies with MOST, D2B, IDb1394, IEEE1394 (registered trademark), or the like using optical communication, or an industrial LAN or FlexRay.

In the three database distribution nodes 4, 4a and 4b are connected via a transmission line 5a, 4b and 4c are connected via a transmission line 5b, 4c and 4a are connected via a transmission line 5c, Three database distribution nodes 4a to 4c are connected in a ring shape.
Specifically, the port 12a of the Ethernet communication means 12 in the database distribution node 4a is connected to the port 12b of the Ethernet communication means 12 in the database distribution node 4b by the transmission path 5a. The port 12a of the database distribution node 4b is connected to the port 12b of the database distribution node 4c by the transmission line 5b. Further, the port 12a of the database distribution node 4c is connected to the port 12b of the database distribution node 4a through the transmission line 5c to form a ring connection.

Two transmission lines 5 a, 5 b, 5 c are provided and connected between the database distribution nodes 4.
In this embodiment, the transmission line 5c is a spare line when a failure occurs in the transmission lines 5a and 5b, and thus is a ring connection, but actually, a daisy chain using the transmission lines 5a and 5b. It is used as a connection. That is, one line 5a-1 of the transmission line 5a and one line 5b-1 of the transmission line 5b are for the forward path, and another line 5b-2 of the transmission line 5b and another line 5a-2 of the transmission line 5a are connected. Used for return trips.

The Ethernet communication means 12 provided in each of the database distribution nodes 4 is an interface (not shown) that is directly connected to the in-vehicle LAN 9 and exchanges electrical signals, and a communication that controls communication based on Ethernet using this interface. Controller (not shown).
The Ethernet communication means 12 is connected to the in-vehicle LAN 9 through the port 12a and the port 12b which are interface connector parts, and transmits and receives various update data D. Each of the port 12a and the port 12b has a transmission unit and a reception unit, and enables full-duplex communication. In the case where the in-vehicle LAN 9 performs optical communication, it is appropriately modified such as providing an optical transmission / reception unit as the in-vehicle LAN communication means.

The CAN communication means 11 serving as an ECU side connection means provided in the database distribution node 4 is connected to the ECU 2 via the CAN bus 8 to input / output various update data.
Although it has a CAN transceiver and a CAN controller, in the case where an in-vehicle LAN such as LIN is used for the connection part between the ECU 2 and the database distribution node 4, a communication means and a communication controller compliant with LIN are required as the CAN communication means 11. It is. Further, when the in-vehicle LAN is not used for the connection part between the ECU 2 and the database distribution node 4, an interface as a communication means can be formed. In this case, ECU2 is a control part which comprises the output means of the update data D provided in the sensor 6 side.

  Further, in the database 7 of the recording means 12 of the database distribution node 4, the update data D obtained from the sensor 6 via the ECU connected to the database distribution node 4 is recorded as it is without being processed.

As shown in FIG. 2, at least identification information ID (IDa, IDb...) Of the update data D and attribute value data VDa, VDb. Of the update data D recorded in the recording means 21 of the other database distribution node 4 received via the LAN 9, the database distribution node 4 also records necessary update data.
In FIG. 2, “wheel speed” or the like is shown as the identification information ID, but an identification information ID consisting of a predetermined number of bits may be used. Similarly, the attribute value data VDa... Is an example of the attribute value data VDa... But the attribute value data VDa... Recorded in the database 7 must include unit information. It doesn't mean.

  As the recording means 21, a RAM configured to be readable and writable by the data output means 23 is used, and the stored contents can be retained even when the power supply is interrupted using a backup power source or the like. Note that rewritable recording means having non-volatility such as a flash memory may be used. Also, in the recording means 21, there are output timing setting tables Ta to Tc (hereinafter referred to as an output timing setting table T when distinction is unnecessary) set by the output timing setting means 22 and used by the data output means 23. Each is recorded.

  In this embodiment, since the output timing setting table T is dynamically set by the output timing setting means 22, the recording means 21 for recording the output timing setting table T needs to be rewritable. However, this output timing setting table T may be fixedly set. In this case, the memory 12 in which the table T is recorded may be a ROM.

The data output means 23 for outputting the update data D recorded in the recording means 21 to the ECU 2 side reads and writes the update data D in the database 7 of the recording means 12 and outputs it to the ECU 2 that requires the update data D. It is. The output timing setting means 22 sets the output timing of the update data D.
When the update data D is input via the data output means 23, the database update means 24 registers the corresponding update data in the database 7 of the recording means 12, and sends the update data frame including the update data D to the in-vehicle LAN 9. The update data D of another node included in the update data frame received from the adjacent database distribution node is registered in the database 7 while being transmitted to the adjacent database distribution node.

Below, the operation | movement in the vehicle-mounted database system 1 of this invention which consists of the said structure is demonstrated.
First, each ECU 2 receives a detection value from the connected sensor 6. The ECU 2 transmits the received update data D to the database distribution node 4 to which the ECU 2 is connected. Each database distribution node 4 records the update data D in the database 7.

Each database distribution node 4 writes the update data D recorded in the database 7 to the update data frame and transmits it to the transmission line 5 at the timing set by the database update means 24. The database distribution node 4 that transmits the updated data frame first is assumed to be a master node. The update data frame transmitted from the master node is sequentially circulated to the adjacent database distribution nodes 4 via the transmission path 5, and the update data D newly recorded in the database 7 is updated at each database distribution node 4. Write to. This operation is performed up to the loopback node as the last database distribution node.
By writing the update data D into the update data frame in the loopback node, the update data frame is recorded in the database 7 of all the database distribution nodes 4 on the forward path of the transmission path 5 from the master node to the loopback node. Data D is written.

Next, in the return path from the loopback node to the master node, the update data frame in which all the update data is written sequentially circulates through the database distribution node, and each database distribution node 4 includes the update data frame from all the update data D. The necessary update data D is read.
The update data D newly acquired in this way is recorded in the database 7 of the database distribution node 4, and the update data D is transmitted to the ECU 2 connected to the database distribution node 4 at a preset timing. Necessary control is performed based on the update data D.

Hereinafter, the operation will be described in detail.
First, each ECU 2 receives a detection value from the connected sensor 6. The detected value is transmitted as update data D to the database distribution node 4 at a timing determined by each ECU 2. In the database distribution node 4, these update data D are recorded in the database 7 of the recording means 21. Then, the update data D is transmitted and received between the database distribution nodes 4a to 4c, and the update data D is shared.

Next, transmission / reception of update data will be described with reference to FIG.
As described above, the database distribution node 4 a receives the update data Da from the ECU 2 a connected to its own node via the CAN communication means 11 and registers it in the database 7 in the memory 12.

  First, the database distribution node 4a creates an update data frame D1. The database update unit 24 writes the update data Da in the update data frame D1, and transmits it from the port 1 of the Ethernet communication unit 12 to the database distribution node 4b. Here, the database distribution node 4a is a master node, and inputs and collects update data frames to the in-vehicle LAN 9. Normally, only one master node exists on the ring connected by the in-vehicle LAN 9. The other nodes are called slave nodes.

  The database distribution node 4b receives the update data frame D1 via the port 2 of the Ethernet communication means 12 of its own node, adds the update data Dd registered in its own database 7 to the update data frame D1, and To do. The database distribution node 4b transmits the update data frame D2 to the database distribution node 4c.

  The database distribution node 4c receives the update data frame D2, adds the update data Dg registered in its own database 7 to the update data frame D2, and sets it as the update data frame D3. Thereafter, the database distribution node 4c reads the update data required by the ECUs 6g and 6h among the update data Da and Dd of the other nodes and registers them in the database 7. The database distribution node 4c transmits the update data frame D3 to the database distribution node 4b.

  Here, the database distribution node 4c is a loopback node that loops back and transmits the update data frame, and there is only one on the ring when it is normal. The loopback node is the most downstream database distribution node from the master node through all other database distribution nodes.

The database distribution node 4b receives the update data frame D3, reads necessary update data among the update data Da and Dg of other nodes, and registers them in the database 7. Thereafter, the update data frame D3 is transmitted to the database distribution node 4a.
The database distribution node 4a receives the update data frame D3 and registers it in the necessary read database 7 among the update data Dd and Dg of other nodes.

As described above, when the database distribution node 4a, which is the master node, inputs the update data frame to the in-vehicle LAN 9, each database distribution node 4 updates the update data frame in the order of 4a → 4b → 4c (the forward direction). To write update data. Returning at the database distribution node 4c, which is a loopback node, in the return path (reverse direction), each node reads data other than the update data written by itself. In this embodiment, the update data written by each node is one update data Da, Dd, and Dg for each node. However, a plurality of update data may be written.
As the update data circulates between the database distribution nodes 4 in this way, the database 7 of each database distribution node 4 is updated and the update data is shared.
Such update data frames are periodically circulated. While the update data frame is circulating, the update of the database of each node is not completed and the update data is not shared. However, after the cycle, the database of each node is the same until the next update data frame is cycled. Has update data and shares update data.

  In this embodiment, the database distribution node 4c is a loopback node, but 4b may be a loopback node. In this case, the update data frame circulates in the order of the database distribution nodes 4a → 4c → 4b.

Next, a method in which each database distribution node 4 adds its own update data to the update data frame will be described.
FIG. 4 is a detailed explanatory diagram when the database distribution node 4a adds update data as an example.
Update data supplied from the ECU of each node is registered in the database 7 of the database distribution node 4a. If the update data Da, Db is newly updated among the update data Da, Db, Dc obtained from the ECU of the own node 4a, the database distribution node 4a includes the update data Da in the update data frame D1. Write Db.

  Here, the format of the update data frame will be described. The update data frame includes a header portion and an attribute value data portion. The header part is composed of a data independent part, the number of data, the data ID, the data length, and the reservation flag, and the attribute value data part is composed of attribute value data.

Therefore, the data independent part, the number of data, the data ID of each of the update data Da and Db, the data length, and the reservation flag are written in the header part of the update data frame D1. The attribute value data of the update data Da and Db is written in the attribute value data part after the header part. This update data frame D1 is transmitted from the port 1 of the Ethernet communication means 12 to the database distribution node 4b.

  Assuming that update data Dd and De are newly updated among update data Dd, De and Df obtained from the ECU connected to database distribution node 4b, database distribution node 4b receives update data frame D1. After that, the update data Dd and De are written into the update data frame D1. The data ID, data length, and reservation flag of each of the update data Dd and De are written in the header part of the update data frame D1, and the attribute value data of the update data Dd and De are written in the attribute value data part. The new update data frame in which the update data Dd and De are written in this way is defined as an update data frame D2.

Similarly, also in the database distribution node 4c, the update data of Dg newly updated is written in the update data frame D2, and is set as the update data frame D3. Update data Da, Db, Dd, De, and Dg are written in the update data frame D3.
In the database distribution node 4c that is a loopback node, the update data frame D3 is transmitted in the reverse direction, and each node reads the update data of another node whose destination is the own node from the update data frame D3.

FIG. 5 illustrates the time for the update data frame to cycle through each database distribution node 4. The transmission paths 5a, 5b, and 5c of the in-vehicle LAN 9 are composed of two transmission paths and perform transmission in a full duplex system.
When the update data frame D1 is transmitted from the port 1 of the Ethernet communication means 12 of the database distribution node 4a, it is received at the port 2 of the database distribution node 4b. These transmission and reception are performed almost simultaneously.

  In the database distribution node 4b, the update data frame D1 is stored in the buffer. When the data length to be buffered (buffering length) is exceeded, the update data frame in which the update data Dd and De of its own node are newly written from the port 1 D2 transmission is started. In this embodiment, the data length of the data-independent part of the header part is the buffering length, and when the data-independent part is received, transmission of the update data frame D2 is started. As shown in FIG. 5, the time t1 at which the transmission of the update data frame D2 is started is the byte time T1 (one byte is received via the in-vehicle LAN) when the time at which the update data frame D1 is transmitted is the reference time t = 0. Is the time obtained by multiplying the buffering length B1 of the data frame.

  The database distribution node 4c buffers the update data frame D2, and when the data independent part of the header portion of the update data frame D2 is received in the same manner as the database distribution node 4b, the update data in which the update data Dg of its own node is written The frame D3 is transmitted from the port 2 of the database distribution node 4c toward the database distribution node 4b. Assuming that the forward buffering length is constant in each database distribution node, the transmission start time t2 is the time when twice the time obtained by multiplying the byte time T1 by the forward buffering length B1 of the data frame has elapsed.

  The database distribution node 4c simultaneously receives the update data frame D2 from the database distribution node 4b and transmits it to the update data frame D3 to the database distribution node 4b. The update data frame is turned back at the database distribution node 4c. Since each port has two transmission lines, the database distribution node 4c can simultaneously receive and transmit the update data frame.

  The database distribution node 4b receives the updated data frame D3 almost simultaneously with transmission. The update data frame is stored in the buffer when the update data frame is transmitted in the backward direction, as in the forward direction transmission in the forward direction. The data length to be buffered is set separately for the forward path and the return path. When the data length B2 for buffering on the return path is exceeded, the update data frame D3 is transmitted from the port 2 to the database distribution node 4a. The database distribution node 4a receives the updated data frame D3 almost simultaneously with transmission. The time t3 at which the database distribution node 4b starts transmission to the database distribution node 4c is (data frame forward path buffering length B1 × 2 + data frame return path buffering length B2) × byte time T1.

  Furthermore, the time t4 from when the database distribution node 4a as the master node transmits the update data frame to the vehicle-mounted LAN until the database distribution node 4a receives the update data frame again is t3 + data frame maximum length B3 × byte time T1 It becomes.

  Therefore, the update data frame maximum cycle time T (time required for one cycle of the update data frame) is ((node number−1) × forward buffering length B1 + (node number−2) × return buffering length). B2 + maximum data frame length B3) × byte time T1.

In the first embodiment, there are two transmission lines 5a to 5c, for example, 5a-1 and 5a-2 are connected as the transmission line 5a, and one of the two transmission lines is updated in the forward direction and the other is updated in the reverse direction. The data frame is circulated.
On the other hand, when the transmission lines 5a to 5c are one by one, the update data frame can be circulated by a half-duplex method in which each port has a transmission / reception unit and one transmission line 5a, 5b is used for transmission / reception. The time course of the half-duplex method is shown in FIG. Unlike the full-duplex method, the half-duplex method has one transmission line. For this reason, the node 4c cannot receive and transmit update data at the same time, and after receiving all the update data frames D2 from the node 4b, transmits to the update data frame D3 to the node 4b. For this reason, the time t1 is the same as the full-duplex method, but the transmission time t2 from the node 4c to the node 4b is (data frame forward buffering length B1 + data frame maximum length B3) × byte time T1. .

  Furthermore, the transmission start time t3 of the update data frame from the node 4b to the node 4c is (outbound buffering length B1 + returning buffering length B2 + data frame maximum length B3) × byte time T1. The time t4 from when the database distribution node 4a as the master node transmits the update data frame to the in-vehicle LAN until the database distribution node 4a receives the update data frame again is t3 + data frame maximum length B3 × byte time T1. .

Therefore, the update data frame maximum cycle time T (time required for one cycle of the update data frame) is ((node number−2) × forward buffering length B1 + (node number−2) × return buffering length). B2 + maximum data frame length B3 × 2) × byte time T1.
Compared to the full-duplex method, the transmission direction of one transmission path is alternately switched, so there is a drawback that it takes time to transmit, but the configuration is simple because there is only one transmission path.

  Each database distribution node 4 performs error detection / correction of the update data frame. The error detection / correction of the update data frame is made up of (1) a data-independent portion of the header, (2) the number of header data, (3) a set of data ID and data length for each header data, (4 ) Each attribute value data (part excluding data ID and data length) is divided into blocks, and this is performed for each block. The data ID and data length are placed in the header part and separated from the attribute value data part.

For the header part of the update data frame, block in the update data frame at all nodes in the update data frame when the update data is created in the forward path and immediately after receiving the update data frame, and in the case of the return path immediately after receiving the update data frame Error detection / correction is performed every time.
If even one uncorrectable error has occurred, the entire update data frame is regarded as an error. When the entire update data frame is regarded as an error, the update data frame up to the block where the uncorrectable error has occurred is transmitted to the next node, and finally transmitted to the master node. By transmitting a block until an error occurs in the master node, the master node can know that an error has occurred in the update data frame. For the portion after the block in which an uncorrectable error has occurred, transmission to the next node is stopped if it is determined as an error.

  For the attribute value data part, when the update data D of another node is read in the return path, error detection / correction is performed for each attribute value data instead of the entire update data frame. If an uncorrectable error has occurred, the attribute value data is regarded as an error. Even if an error occurs in one attribute value data, the entire update data frame is not an error. Even when the attribute value data is an error, the entire update data frame is transmitted to the next node and finally transmitted to the master node.

  The master node checks the returned update data frame, and if an error that cannot be corrected occurs in the attribute value data, as soon as it is decided to retransmit, the update data frame that designates only the attribute value data Resubmit. For retransmission, the same attribute value data transmitted last time is transmitted instead of the attribute value data newly read from the database. Since the data ID and data length are placed in the header part separately from the attribute value data, each node can know the storage position of the attribute value data.

When retransmitting, it is possible to increase the redundancy by designating that one update data is written a plurality of times or by increasing the data length. When the update data D is written a plurality of times, the storage position is released as a measure against a burst error.
Each node writes if the update data D of its own node is designated on the forward path, returns at the loopback node, and reads the update data D of other nodes on the return path. However, if an uncorrectable error has occurred in the header part, the master node does not specify the update data D.

As described above, each database distribution node 4 reads the update data of the ECU 2 of the other node from the update data frame and records it in the database 7.
Next, the timing at which the update data of the other node is transmitted to the ECU 2 connected to the own node will be described.

The ECU 2 receives the update data D from the database 7 via the data output means 23 based on the timing set in the output timing table T.
The data output means 23 can output the update data D at a timing required by the ECU 2 according to the output timing setting table T in the memory 12. When the immediate output request Ra from each ECU 2... Is input, the update data D of the specified identification information ID in the database 7 is output to the CAN bus 8 side in response to the immediate output request. The immediate output request Ra includes the identification information ID for identifying the update data D that requests immediate output.

  Further, in this embodiment, the output timing setting means 22 can input the output request Rb from each ECU 2 and dynamically update the output timing setting table T in each database distribution node 4 according to this output request Rb. It is configured as follows. The output request Rb also includes an identification information ID for identifying the update data D for setting the output timing, a set value of the output timing, and preferably includes a parameter for determining the output timing. .

  FIG. 7 shows an example of the output timing setting table T (particularly, the output timing setting table Tc recorded in the memory 12 in the database distribution node 4c) in the in-vehicle database system 1 shown in FIG. The table T includes identification information IDs of the update data D (representing individual identification information IDs using codes IDa, IDb...) And output timings Ti of the update data D corresponding to these IDs (respective individual timing setting values are indicated respectively). And the parameter Par of the transmission timing of each update data D (each parameter is expressed using the symbols Para, Parb,...), Respectively.

  In the example illustrated in FIG. 7, for the attribute value data VDa whose identification information IDa is “wheel speed”, the output timing Tia is set to “output at change”, and the parameter Para is set to “no thinning”. Therefore, the processing means 13 outputs the update data D... At the timing according to the output timing setting table Tc by the data output means 23, so that the update data D is output to the CAN bus 8 at the timing required by the ECU 2i. can do. That is, when the update data D in the database 7 is updated, it can be output to the CAN bus 8 on the ECU 2h, 2i (see FIGS. 1 and 2) side.

  As in this example, in the output timing setting table T, when setting for setting the output at the time of change without thinning out, the ECU 2i sends the update data D from the ECU 2a with a slight delay for updating the database 8. Except it can be received in real time. In addition, when there is no change in the measured value of the wheel speed, the output of the meaningless update data D can be suppressed by not outputting the update data D to the CAN bus 8.

  Note that “real time output” is set as the output timing Ti, and the update data D is output to the CAN bus 8 every time there is update data input from the ECU 2 even if the value of the update data D does not change. May be. Accordingly, the update data D supply side and the reception side ECU 2 can deliver the update data D in a directly connected manner without being aware of the presence of the database 7 therebetween.

  Conversely, “predetermined output” may be set as the timing Ti, and the update data D updated from each supply side ECU 2 may be thinned out and output to the reception side ECU 2. In this case, by setting the reception time interval of the update data D required by the receiving ECU 2 as the parameter Par, the update data is updated at an interval necessary for the receiving ECU 2 (for example, every second as shown in the parameter Parc). D can be received. As a result, useless communication using the CAN bus 8 can be drastically reduced.

  Further, as shown in the example of FIG. 7, “output when threshold is exceeded” may be set as the output timing Tib. In the case of this example, for the update data D whose identification information IDb is “steering angle”, an output when the threshold is exceeded is set, and the threshold is set to “every ± 5 deg” in the parameter Parb. That is, when the data output means 23 refers to the output timing setting table Tc, the update data D can be output to the CAN bus 8 at intervals of 5 °, for example. This is the timing required by the ECU 2i.

The output timing setting table Tc shown in FIG. 7 discloses “output when changing”, “output when exceeding the threshold”, and “predetermined interval output” as the output timing Ti, and “real time output” can be set in the above description. However, these terms are intended to make the present invention easier to understand, and the present invention is not limited to these set values. Actually, the output timing set values are numerical values and symbols. It is preferable that Similarly, it goes without saying that the above description is not an important factor for the parameter Par as well.
The update data transmitted to the ECU 2 connected to the own node may be not only the update data of the ECU 2 connected to the other node but also the update data of the ECU 2 connected to the own node.

  As described above, a daisy chain in which transmission paths 5a and 5b are provided between database distribution nodes 4a and 4b, 4b and 4c in order to transmit update data D by circulating update data frames between database distribution nodes 4. The nodes may be connected in a state. However, when a failure such as a disconnection occurs in the transmission lines 5a and 5b, the update data D cannot be transmitted / received. Therefore, in the first embodiment, the transmission path 5c is also connected between the database distribution nodes 4c and 4a to form a ring connection.

When the database distribution node 4a is a master node and the database distribution node 4c is a loopback node and the update data frame circulates in the order of 4a → 4b → 4c, the transmission line 5c is usually not used. Here, consider the case where one of the transmission paths cannot be transmitted / received due to a failure. FIG. 8 is an explanatory diagram when transmission / reception is not possible due to a failure in the transmission path 5a. The master node 4a cannot transmit the update data frame and cannot update the database. Therefore, when the in-vehicle database system detects a failure in the transmission path 5a, the update frame is circulated using the database distribution node 4b as the master node, the database distribution node 4a as the loopback node, and the nodes 4b → 4c → 4a as the forward direction. Then, the database of each database distribution node 4 is updated.
Thus, by duplicating the transmission path, the update data D can be transmitted and received even if a certain transmission path 5 breaks down, resulting in a highly reliable system.

FIG. 9 is an explanatory diagram of the second embodiment. The connection of each database distribution node is the same ring shape as in the first embodiment, but the update data frame circulation method is different. The update data frame transmitted in one direction from the master node circulates around each database distribution node and returns to the master node. The update data frame is rotated twice in the direction from the master node 4a to 4b, 4c, each database distribution node 4 writes the update data D of its own node in the first cycle, and each node stores the update data D of other nodes in the second cycle. The database 7 of each database distribution node 4 is updated by reading. The patrol may be in the order of 4a → 4c → 4b. Such a cyclic method of updating data frames is called a ring method.
In addition, when the method in which the update data frame circulates between the master node and the loopback node as in the first embodiment is called a daisy chain method, in the first embodiment, the in-vehicle database system 1 is physically ( The connection between each database distribution node is a ring shape, but theoretically (update data frame cyclic method) is a daisy chain method. On the other hand, in the second embodiment, the in-vehicle database system 1 is physically connected in a ring shape and theoretically shares the update data D in a ring manner.

  In the second embodiment, the two transmission lines 5a to 5c circulate update data frames having the same contents in the same direction. Even if the update data frame is not transmitted due to the failure of one transmission path, the update data frame is transmitted via the other transmission path, and the database 7 of each database distribution node can be updated.

  Further, when a failure occurs in any one of the transmission lines 5a to 5c, the database distribution node 4 on one side sandwiching the failure point is set as a master node, and the database distribution node 4 on the other side is set as a loopback node. An update data frame can be circulated between the node and the loopback node. That is, when the transmission line 5 fails, it is physically connected in the form of a daisy chain as in the first embodiment, and the update data frame is logically circulated by the daisy chain method.

  Further, FIG. 10 shows an example of database distribution node connection and update data frame transmission. In FIG. 10, only the database distribution node 4 and the transmission path 5 are shown for explanation, and the ECU 2, the sensor 6, and the like are not shown.

In FIG. 10A, the database distribution nodes 4 are each connected by a single transmission line 5 in a daisy chain manner. An update data frame can be transmitted in the half-duplex method described above.
In (b), the database distribution nodes 4 are connected in a daisy chain by two transmission lines 5 respectively. The same update data frame is transmitted to the two transmission lines 5, and communication is performed by the half-duplex method described above. Even if a failure occurs in one of the two transmission lines 5, an update data frame can be transmitted through the other transmission line 5, and reliability can be ensured.
(C) The connection of the database distribution node 4 is the same as that of (b), but in the full-duplex system described above using two transmission lines 5, one of the transmission lines 5 is forward and the other is connected. The update data frame is transmitted in the reverse direction. High-speed communication is possible.

(D) is different from the first embodiment in that each database distribution node 4 is connected by one transmission line 5. The update data frame is transmitted by the half duplex method described above. The transmission line 5c is a spare line when another transmission line fails.
(E) is different from the second embodiment in that each database distribution node 4 is connected by a single transmission line 5. The update data frame makes a round between the database distribution nodes 4, writes the update data D into the update data frame in the first round, and reads the update data D of other database distribution nodes in the second round.
(F) differs from the second embodiment in the cyclic method of the update data frame. In the second embodiment, update data frames having the same contents are circulated in the same direction on the two transmission lines 5a to 5c by the ring method. In (f), update data frames having different contents are circulated in the same direction. Yes. High-speed communication is possible by circulating update data frames having different contents.
(G) differs from (f) in that an update data frame having different contents is circulated in the reverse direction.
Even if update data frames having different contents are transmitted in the reverse direction, the update data frames can be circulated, and high-speed communication is possible.

Further, in the first embodiment, the second embodiment, and FIGS. 10B, 10C, 10F, and 10G, two transmission lines 5a to 5c are connected to each other, but a plurality of transmission lines are provided. The update data frame can be transmitted and received in two sets. By sending an update data frame with the same content to a transmission line included in one set, even if a failure occurs in one of the transmission lines, the update data frame can be sent on the other transmission line, and reliability is improved. It can be secured.
Furthermore, high-speed communication is possible by transmitting update data frames having different contents for each group.

  In the first embodiment, the second embodiment, and FIG. 10, the number of database distribution nodes is three. However, the number is not limited because it corresponds to the number of ECUs divided into groups. Therefore, the number of transmission lines connecting the database distribution nodes is not limited, and any configuration may be used as long as the database distribution nodes are sequentially connected.

It is a figure which shows the structure of the vehicle-mounted database system which concerns on 1st Example of this invention. It is a figure which shows the specific example of a database. It is explanatory drawing in the case of updating the database of a database distribution node. It is explanatory drawing in the case of writing data in an update data frame within a database distribution node. It is a time chart in the case of transmitting by a full duplex system. It is a time chart in the case of transmitting by a half duplex system. It is a figure which shows the specific example of an output timing setting table. It is explanatory drawing when a failure occurs in a transmission line. It is a figure which shows the structure of the vehicle-mounted database system which concerns on a 2nd Example. It is a figure which shows the example of connection of a database distribution node, and transmission of the data frame for an update. It is a figure which shows the structure of the communication system between ECU connected by the conventional vehicle-mounted LAN. It is a figure which shows the structure of the communication system between ECUs using FlexRay. It is a figure which shows the structure of the communication system which connects several ECU logically using the trunk line in which high speed communication is possible.

Explanation of symbols

1 In-vehicle database system 2 ECU
4 Database distribution nodes 5a, 5b, 5c Transmission path 6 Sensor 7 Database 9 In-vehicle LAN
11 CAN communication means 11
12 Ethernet communication means 21 Memory 22 Output timing setting means 23 Data output means 24 Database update means D1, D2, D3 Update data frame

Claims (8)

A plurality is provided ECU per group with divided into a plurality of groups,
An in-vehicle LAN having a database distribution node connected to the ECU in each group and provided one for each group; and a transmission line sequentially connecting the database distribution nodes provided for each of the plurality of groups;
Each of the database distribution nodes includes a processing unit having a database, ECU side transmission / reception means for transmitting / receiving data between the processing unit and the connected ECU, and update data recorded in the database of the processing unit. Inter-node transmission / reception means for transmitting / receiving to / from other database distribution nodes,
Each database distribution node and each ECU are connected via an in-vehicle LAN, and each ECU transmits update data from the connected sensor to the database distribution node and records it in the database,
The update data recorded in the database of the one database distribution node is sequentially circulated to the other database distribution nodes through the transmission path so that the other database distribution nodes can receive the update data. Update data from other database distribution nodes recorded in the database of the other database distribution node and shared in the database of the other database distribution node is sent to the ECU in accordance with the set timing or a transmission request from the ECU side. An in-vehicle database system characterized by being configured to transmit . The transmission path between the database distribution nodes is configured such that adjacent database distribution nodes are connected in a daisy chain, one database distribution node connected in the daisy chain is used as a master node, and the other database distribution node is connected to the database distribution node. A loopback node,
In the forward path from the master node to the loopback node, the update data frame for writing the update data recorded in the database in each database distribution node is circulated, and in the return path from the loopback node to the master node, all the update data is stored. The in-vehicle database system according to claim 1, wherein the written update data frame is circulated to update the database by reading update data required in each database distribution node.   The master node and the loopback node are further connected via an additional transmission line to connect the database distribution nodes in a ring shape. When a failure occurs in the transmission line, the failure part is sandwiched. The in-vehicle database system according to claim 2, wherein the database distribution node on one side is a master node and the database distribution node on the other side is a loopback node, and the update data frame is circulated between the master node and the loopback node. . The transmission path between the database distribution nodes connects adjacent database distribution nodes in a ring shape,
One of the database distribution nodes connected in the ring shape is a master node,
Rotating the update data frame in one direction from the master node,
In the first round, the update data recorded in the recording means of each database distribution node is written in the update data frame,
The in-vehicle database system according to claim 1, wherein, in the second round, the database is updated by reading update data required in each database distribution node from an update data frame in which all update data is written.   When a failure occurs in the transmission line, the database distribution node on one side sandwiching the failure point is used as a master node, the database distribution node on the other side is used as a loopback node, and between the master node and the loopback node. The in-vehicle database system according to claim 4, wherein the update data frame is circulated. Before providing a plurality of transmission paths that connect the Kide database distribution node, vehicle according to any one of claims 2 to 5 is circulated the same update data frame in the same direction using the transmission channel of the plurality of Database system. The in-vehicle system according to any one of claims 2 to 6, wherein a plurality of transmission paths connecting the database distribution nodes are provided, and a plurality of different update data frames are circulated in the same direction using the plurality of transmission paths. Database system. 8. The system according to claim 2 , wherein a plurality of transmission lines are provided for connecting the database distribution nodes, and some of the transmission lines are circulated in the forward direction, and the remaining transmission lines are circulated in different directions. The in-vehicle database system according to claim 1.

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