KR100773076B1 - Method for transmitting and receiving dynamic can communication data - Google Patents

Abstract

An active CAN(Controller Area Network) communication data transmitting/receiving method is provided to reduce a message transmission time, a bus load, and the average length of messages by transmitting/receiving the message between ECUs(Electronic Control Unit) of a vehicle through an active CAN communication data compression algorism. An active CAN communication data transmitting/receiving method includes the steps for transmitting a message before compressed, in case of the first message in transmitting the compressed message by using a CAN protocol; calculating difference between control data generated at the first predetermined time and control data generated at the second predetermined time in a transmission ECU; checking whether each control data difference value is smaller than the defined data of the compressed message or not; preparing the compressed message if each control data difference value is smaller than the defined data of the compressed message, and transmitting the message before compressed if any one of data is larger than the specific size; and marking the change rate of each data in each corresponding bit included in an RFC(Reduction Flag Code) in generating the compressed message, and then storing new data generated at the second predetermined time, in a Tx-Buf(Buffer) and transmitting the compressed message.

Description

Active CAN communication data transmission / reception method {METHOD FOR TRANSMITTING AND RECEIVING DYNAMIC CAN COMMUNICATION DATA}

1 is a configuration diagram of a message before the CAN communication compression of a conventional vehicle network,

2 is a configuration diagram of a CAN communication compression message of a conventional vehicle network;

3 is a process for restoring a CAN communication compression message of a conventional vehicle network;

4 is a diagram illustrating a network system configuration of a vehicle using a CAN protocol to which an embodiment of the present invention is applied;

5 is a flowchart illustrating a CAN communication compression message transmission process according to an embodiment of the present invention;

6 is a configuration diagram of a message before the CAN communication compression of a conventional vehicle network,

7 is a configuration diagram of a CAN communication compression message according to an embodiment of the present invention;

8 is a flowchart illustrating a CAN communication compression message reception process according to an embodiment of the present invention;

9 is a diagram illustrating a restoration process of a CAN communication compression message of a vehicle network according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system of an automobile, and more particularly, to an active CAN communication data transmission / reception method in an automobile network that enables efficient networking between various electronic devices in a vehicle using a CAN protocol.

Recently produced and sold automobiles include ABS system, A-back system, attitude control system (TCS), headlight control system (AFS), cruise control system (VCC), Throttle by wire, advanced high safety automotive electronic equipment, A number of electronic control devices such as telematics and intelligent transportation systems (ITS) are being applied, and such advanced systems are increasingly required for the safety and convenience of automobiles, and related electronic equipments will increase exponentially.

In addition, due to environmental regulations, hybrid cars, which are being combined with existing engines and batteries / fuel cells, are expected to replace conventional fossil fuel cars, and such hybrid cars require much more electronic equipment. The advent of hybrid cars is expected to accelerate the number of related electronic devices in the implementation of advanced systems in the car.

Most of each ECU in such electronic equipment is connected to the CAN communication network, but because of the enormous amount of communication data increase and high safety, it will require faster communication speed than conventional electronic equipment. Existing CAN communication networks are expected to have difficulties in implementing the functions.

In order to solve this problem, the expansion of several network lines (CAN, LIN, MOST, etc.), or the development of new communication protocols (Flexlay, etc.) that enable higher bandwidth and communication speeds, increases the cost, and frequently causes failures due to complicated wiring. There was a problem incurred maintenance costs.

As an alternative, active CAN communication data compression algorithms are required for network efficiency, such as utilizing existing bandwidth networks, minimizing network traffic, and improving bus utilization.

The above electronic control devices in the vehicle are one-way or two-way communication between the sensing unit, the sensor, and the operating unit such as sensors, etc. Currently, ECUs of each electronic control device are connected to the CAN communication network so that messages necessary for various control are transmitted. It is delivered.

Referring to the data transmission / reception operation in the CAN communication network, the CAN communication data is composed of message units to perform communication in a message unit, and each ECU mounted in the electronic equipment can transmit several messages, and each message has priority. And a unique message ID having an identifier function, data consisting of 8 bytes or less, an ID field of 46 bits (for CAN 2.0A) necessary for communication, and a control bit.

In addition, each ECU can receive a message if a desired message ID occurs on the communication bus. The lower the ID number, the higher the priority. At this time, the data can be composed in byte unit up to 1 byte, 2 byte, ..., 8 byte, and the send / receive data in the message can be configured freely in bit unit within the allowable data size. The transmitting side can transmit and receive data according to a predefined data configuration.

Accordingly, when a message is to be transmitted from each electronic device, the change amount between the data t immediately before the transmission and the data to be transmitted (t + Δt) is compared. If the change amount is within a predetermined range, the data includes only the change amount. Is sending a compressed message. At this time, the ID of the compressed message is subtracted from the value of '1' from the message ID before compression. That is, if the message ID before compression is 100, the ID of the compressed message is 99.

1 and 2 show the conventional CAN data compression process flow, and as shown in FIG. 1, the engine speed (2 bytes), engine temperature (1 byte), gas level (1 byte), engine force (2 bytes), and engine power (2 bytes) Assume that there are 8 bytes of data defined and a message with an ID of 100.

Then, as shown in FIG. 2, the compressed message for transmitting only the amount of data change is predefined as the data sorting order and size, and the ID of the compressed message is obtained by subtracting 1 from the message ID before compression.

The transfer ECU calculates ΔMsg, which is the difference between the transmission data at any time t and the transmission data at t + Δt. That is, for example, if the engine speed data, ΔES = _{t + Δt} is the ES -ES _t. Data transmitted at time t is previously stored in Tx-Buf, and data at time t + Δt is new data newly generated.

If each ΔMsg value is smaller than the data size defined in the compressed message, the compressed message is transmitted. If any one data is larger than the defined size, the message before the compression is transmitted. In the case of a compressed message, the first byte of data is used as a reduction flag code (RFC) to determine the amount of data change.

If each bit in the RFC is '1', data is generated by adding the data change amount ΔMsg to Rx-Buf. If the bit is '0', it means that there is no data change amount. Therefore, the value in Rx-Buf is used as it is.

3 shows data changes of conventional engine force (EF), engine speed (ES), gas level (GL), engine temp (ET), and engine power (EP), respectively, 0, 0, +5, -4,- If it is assumed that the amount of data change is smaller than the predefined size as 14, a compressed message is transmitted, and at the receiving side, new data at time t + Δt is generated by adding ΔMsg to Rx-Buf that was storing data received at time t. The process is illustrated.

As shown in FIG. 3, EF and ES have no data change amount, and GL, ET, and EP represent a process of constructing a compressed message when it is assumed that the data does not fall within a defined limit. In the bit value of the RFC, since EF and ES are 0, the Rx-Buf value is used as it is, and GL, ET, and EP calculate 'Rx-Buf + ΔMsg' to generate new data.

However, in the compression process of the conventional CAN data as described above, although the engine force and the engine speed are transmitted as shown in FIG. 3 with 8 bit size, respectively, in the fixed compression message as shown in FIG. I can see that

At this time, only 5 bits are needed to display only the amount of change of 5 data, but there is always a problem that 3 bits are wasted because 8 bits are occupied. There is a problem in that compression efficiency is lowered, such as the need to transmit a fixed compressed message of bytes.

Accordingly, an object of the present invention is to provide an active CAN communication data transmission / reception method in an automobile network that enables efficient networking between various electronic devices in a vehicle using a CAN protocol.

In order to achieve the above object, the present invention provides an active CAN communication data transmission method comprising the steps of: (a) transmitting a pre-compression message when the first message is transmitted when the compressed message is transmitted using the CAN protocol; Calculating ΔMsg, which is the difference between the control data at any time t and the control data at t + Δt, and (c) checking whether each of the ΔMsg values is smaller than the defined data size of the compressed message. And (d) preparing a compressed message when each ΔMsg value is smaller than the data size defined in the compressed message, and transmitting a pre-compression message when any one data is larger than the defined size; and (e) the compressed message. Storing new data generated at the time t + Δt at the time of message generation in Tx-Buf and transmitting a compressed message.

In addition, the present invention is an active CAN communication data receiving method, (a ') using the CAN protocol to store the compressed message received at time t in Rx-Buf, and (b') the amount of data change from the CAN compressed message Reading information; (c ') determining whether there is a data change amount of various control-related data transmitted in the CAN compression message by using the RFC of the compressed message, and (d') Extracting the data change amount ΔMsg according to compression; and (e ') generating data at time t + Δt by adding the data change amount ΔMsg to the data received at time t stored in the Rx-Buf. It is done.

Hereinafter, with reference to the accompanying drawings will be described in detail the operation of the preferred embodiment according to the present invention.

4 is a diagram illustrating a network system configuration of a vehicle using a CAN protocol to which an embodiment of the present invention is applied.

As shown in FIG. 4, the BCM block 400 communicating data related to the body of the vehicle with various ECU blocks through a CAN bus, a mirror operation signal, a fold operation signal, a window operation signal, a seat and a handle. The drive door module block 402 communicates the tilt signal, the memory related signal, and the like with the various ECU blocks through the CAN bus 408, and whether or not the lock and the opening / closing door associated with the trough line can be closed through the CAN bus 408. Assist door module block 404 which communicates with various ECU blocks, power sheet ECU block which communicates with various ECU blocks via CAN bus 408 with data related to transmission of the vehicle and data related to various motors for control of the seat. Tilt ECU block 410 that communicates data related to 406 and steering wheel tilt control, telescope control, inside mirror control located inside the vehicle, and the like with various ECUs via CAN bus 408. ), And the like.

5 and 8 illustrate a flow of compressed message transmission / reception during CAN data communication between each ECU of a plurality of electronic control apparatuses provided in an automobile according to an exemplary embodiment of the present invention.

Hereinafter, referring to FIG. 5, the flow of a compressed message transmission process in the CAN protocol according to the present invention will be described. A transmission ECU attempts to transmit a compressed message for various control-related data of a vehicle using a CAN protocol to another ECU in the vehicle. In this case, it is checked whether the compressed message to be transmitted is the first message (S500), and if the first message is stored in the Tx-Buf (S502), the pre-compression message is transmitted (S504).

As shown in FIG. 6, the vehicle control-related data includes an engine speed (ES), an engine temperature (Engine Temp: ET), a gas level (GL), and an engine force: EF), Engine Power (EP) data, etc., and the data structure when the data is compressed is EF (8Bit) → ES (8Bit) → GL (4Bit) → ET (4Bit) → EP (8Bit). The ID of compressed message is defined as 'ID-1' before compression.

At this time, if the transmission message to be transmitted is not the first message, the transmitting ECU calculates ΔMsg, which is the difference between the transmission data at any time t and the transmission data at t + Δt, and the data at time t and the data at t + Δt. Is compared (S506). In the above ΔMsg calculation, for example, the engine speed ES may be calculated as ΔES = ES _{t + Δt} − ES _t .

The data transmitted at the time t is stored in Tx-Buf in advance, and the data at the time t + Δt is newly generated new data.

Subsequently, the transmission ECU checks whether the magnitude of all data changes is smaller than the data size defined in the compressed message (S508), and transmits the pre-compression message when all ΔMsg values are larger than the data size defined in the compressed message. (S504).

On the other hand, if each ΔMsg value is smaller than the data size defined in the compressed message, an RFC value for the compressed message is prepared, and a code according to the amount of data change is prepared (S510).

Subsequently, the transmission ECU mounts an RFC and prepares a compressed message as shown in FIG. In other words, when generating the compressed message, check whether there is any data change and record '0' and '1' in the corresponding bit in the RFC. Thereafter, the transmission ECU stores new data generated at t + Δt in Tx-Buf (S514) and transmits a compressed message (S516).

Next, the compressed message reception processing flow in the CAN protocol of the present invention will be described with reference to FIG. 8.

First, when receiving a compression message of vehicle control-related data transmitted through the CAN protocol from the transmitting ECU, the ECU checks whether the received compression message is the first message, and if it is the first message, stores the message in the Rx-Buf.

FIG. 9 illustrates a process of generating original data when a compressed message is received. The RFC of FIG. 9 shows the presence or absence of EF, ES, GL, ET, and EP data changes from the leftmost bit, and EF and ES have no data changes. It can be seen that the corresponding bit is '0'. Accordingly, it can be seen from FIG. 7 that only GL, ET, and EP data change amounts are attached to the compressed message.

On the other hand, the receiving ECU checks the message ID when the received compressed message is not the first message. At this time, when the message ID having a value of '99' is received, the receiving side determines whether there is a compressed message (S804). That is, when a message ID having a value of '99' is received at the data receiving side, the first 5 bits are used to determine whether there is a change amount of EF, ES, GL, ET, and EP according to a predefined data configuration (S806). It extracts data whose bit value is '1' with the fixed size.

That is, FIG. 9 recognizes that the change amount of only GL, ET, and EP is transmitted among the five data EF, ES, GL, ET, and EP by receiving the compressed message from the receiving side, extracts the change, and receives the received change at time t. The process of generating new data at time t + Δt by adding ΔMsg to Rx-Buf that stores data.

Accordingly, the receiving ECU calculates the data change amount ΔMsg according to the compression of the data (S808), adds ΔMsg to Rx-Buf that was storing data received at time t, and adds new data at time _{t + Δt} = Msg _{t + Δt} = Calculate as Msg _t + ΔMsg (S810), and store the message in Rx-Buf (S812).

That is, if the existing algorithm is applied, a compressed message of 5 bytes is required as shown in FIG. 2, but when the algorithm of the present invention is applied, a compressed message of 3 bytes is required as shown in FIG. 7. Can be. At this time, if the change amount of all data is '0', only RFC value is needed, so only compressed message of 1 byte size is transmitted. When applying the algorithm of the present invention, the compressed message data of optimal 1 byte to maximum 5 bytes is generated. This becomes possible.

Meanwhile, in the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. That is, the present invention has been described for the transmission and reception of control data, such as engine speed, engine temperature, gas level of the vehicle using CAN communication, but the same in other fields such as factory automation, automotive network, train, ship, aviation, CAN communication is used. It is possible to apply. Therefore, the scope of the invention should be determined by the claims rather than by the described embodiments.

As described above, the present invention can be applied to message transmission / reception between ECUs of an automobile using an active CAN communication data compression algorithm, thereby significantly reducing the message transmission rate, bus load, and average message length. Therefore, it is possible to maximize the usage of the existing CAN communication network by minimizing the communication traffic, and has the advantage of minimizing the network expansion problem.

Claims (22)

As an active CAN communication data transmission method, (a) transmitting a message before compression in the case of the first message when the compressed message is transmitted using the CAN protocol; (b) calculating, at the transmitting ECU, ΔMsg, which is the difference between the control data at any time t and the control data at t + Δt, (c) checking whether each ΔMsg value is smaller than a defined data size of the compressed message; (d) preparing a compressed message when each ΔMsg value is smaller than the data size defined in the compressed message, and transmitting a pre-compression message when any one data is larger than the defined size; (e) displaying whether there is a change amount for each data when generating the compressed message in each corresponding bit in a reduction flag code (RFC), and then storing new data generated at time t + Δt in Tx-Buf and transmitting a compressed message. Active CAN communication data transmission method comprising a. The method of claim 1, In the step (b), the data transmitted at the time t is pre-stored in the Tx-Buf, and the data at the time t + Δt is the newly generated new data. Way. The method of claim 1, The control data includes engine speed (ES), engine temperature (ET), gas level (GL), engine force (EF), engine power (EP) data. Active CAN communication data transmission method, characterized in that any one of. The method of claim 3, If the control data is engine speed (ES), The ΔES value, which is the difference in engine speed at the time t and t + Δt, is expressed by Equation below. [Equation] ΔES = ES _{t + Δt} -ES _t Active CAN communication data transmission method, characterized in that calculated. delete delete delete delete The method of claim 1, The compressed message is an active CAN communication data transmission method, characterized in that formed in 1-5 bytes according to the amount of data change. The method of claim 1, The compressed message is an active CAN communication data transmission method, characterized in that if the amount of all the data change is '0' is generated only one byte size by requiring only the RFC value. The method of claim 10, The compressed message is an active CAN communication data transmission method, characterized in that it is generated in the size of 3 bytes when the data change amount is not '0'. The method of claim 1, The RFC is an active CAN communication data transmission method, characterized in that the bit size is set as the number of data in the compressed message as information for determining whether there is a change amount for each data included in the compressed message. The method of claim 3, The control data is an active CAN communication data transmission method, characterized in that all the data transmitted through the CAN communication protocol between the ECU of a plurality of electronic control equipment mounted in the vehicle. Active CAN communication data receiving method, (a ') storing the compressed message received at time t in Rx-Buf using the CAN protocol; (b ') reading data variation information from the CAN compression message; (c ') determining whether there is a data change amount of various control-related data transmitted in the CAN compression message by using the RFC of the compression message; (d ') extracting the amount of change ΔMsg according to the compression of each control data; (e ') generating data at time t + Δt by adding a data change amount ΔMsg to data received at time t stored in Rx-Buf Active CAN communication data receiving method comprising a. The method of claim 14, In the step (c '), the control data includes an engine speed (Engine Speed: ES), an engine temperature (Engine Temp: ET), a gas level (GL), an engine force (EF), and an engine. Active CAN communication data receiving method, characterized in that any one of the power (Engine Power: EP) data. The method of claim 15, If the control data is engine speed (ES), Engine speed ES _{t + Δt} value at the time t + Δt as in the formula] under [Equation] ES _{t + Δt} = ES _t + ΔES Active CAN communication data receiving method, characterized in that calculated. delete delete delete delete The method of claim 14, The received compressed message is generated by checking each bit information in the RFC, and generating the data change amount ΔMsg to the Rx-Buf when each bit in the RFC is "1". Way. The method of claim 14, The received compressed message checks each bit information in the RFC, and if each bit in the RFC is marked as "0" indicating that there is no data change amount, the received compressed message is used as the data value in the Rx-Buf. Active CAN communication data receiving method.

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