KR20130010809A - Method for reducing distorted signal of high speed control area network - Google Patents

Abstract

PURPOSE: A high speed can signal distortion reduction method is provided to secure the performance of vehicle by selecting a capacitor with optimal capacity under different condition by changing the number of controllers applied to each vehicle. CONSTITUTION: A state of small signal distortion in which an error frame is not found in the process of recognizing a signal by 20% point of 1 bit is judged(S120,S121). A state of normal signal distortion in which an error frame is not found in the process of recognizing a signal by 40% point of 1 bit is judged(S130,S131). An error frame is found in the process of recognizing a signal by 40% point of 1 bit. A state of severe signal distortion in which an error frame is not found in the process of recognizing a signal by 60% point is judged(S140,S141). A state of extremely severe signal distortion in which an error frame is found in the process of recognizing a signal by 60% point is judged(S151). [Reference numerals] (AA,CC,EE) No; (BB,DD,FF) Yes; (S100) Each controller, ECU IGN ON or startup; (S110) Checking the distortion of a CAN signal for each controller(each point of 1 Bit); (S120) Did an error frame occur at a 20% point of 1bit?; (S121) Selecting and controlling capacitor capacity 90pF; (S130) Did the error frame occur at a 40% point of 1bit?; (S131) Selecting and controlling capacitor capacity 60pF; (S140) Did the error frame occur at a 60% point of 1bit?; (S141) Selecting and controlling capacitor capacity 30pF; (S151) Selecting and controlling capacitor capacity 10pF

Description

Method for reducing distorted signal of high speed Control Area Network

The present invention relates to a method for reducing high-speed can signal distortion, and more particularly, to a method for reducing high-speed can signal distortion capable of securing reliability of vehicle communication.

In recent years, with the rapid development of electronic control technology, various devices that were operated by mechanical methods in automobiles are driven by electrical methods for the convenience of drivers and safety of driving, and the system of automobiles is gradually advanced and advanced. Is going.

As the automobile is gradually advanced, the failure forms of the automobiles are diversified, and the failure checking technique and the diagnosis technique for the same are being improved day by day.

Most vehicles currently on the market are equipped with a vehicle controller that receives sensing signals from various sensors and controls each operation on the basis of the vehicle. The vehicle controller includes a PT controller and a vehicle safety device for main components for driving the vehicle. The relevant chassis controller is identified.

PT controllers include an engine management system (EMS) that controls the operation of the engine, and a transmission control unit (TCU) that controls the automatic transmission.

In addition, the chassis controller includes an anti-lock break system (ABS) that controls the operation of the brake, such as preventing the brake from locking during sudden brakes, an electronic controlled suspension (ECS), which is an electronic control suspension, Electronic Stability Program (ESP) to prevent the vehicle from falling off when the driver is unable to balance the vehicle when the situation or severity occurs, and a steering angle sensor (SAS) that informs the vehicle's turning status for anti-slip control when turning the vehicle. ; Steering Angle Sensor (EPB), Electronic Parking Brake (EPB), Adaptive Headlamps to ensure visibility by adjusting the direction of the headlights up and down according to the speed of the vehicle, the steering wheel angle, and the inclination of the vehicle. Adaptive Front Lighting System (AFLS).

Such controllers use high-speed CAN communication when transmitting and receiving data information.

1 is a schematic diagram illustrating a network configuration of a general high-speed can communication, in which two lines, a CAN_High line and a CAN_Low line, are braided. A 120Ω terminating resistor is connected to both ends of the can line (2).

The can high line 1 and the can low line 2 are connected to various controllers, for example, EMS, TCU, ESP, cluster, SAS, Adaptive Cruise Control (ACC), ECS, EPB, AFLS, and the like. Various controllers are connected via can communication, that is, through the can high line 1 and the can low line 2, thereby enabling bidirectional communication.

On the other hand, the internal capacitor of the existing controller is selected to an appropriate capacity in consideration of the electromagnetic noise cancellation and can communication distortion, but in general, the controller manufacturer uses a large capacity capacitor to prevent the controller performance degradation due to external electromagnetic noise.

In addition, the large-capacity capacitor generates some high-speed can communication signal distortion, and the capacitor capacity within the controller once determined is equally applied to all models.

In FIG. 1, reference numeral 3 denotes a diagnostic connector.

However, when the large-capacity capacitors are applied to all vehicles in the same manner, small vehicles having a small number of high-speed can communication controllers are irrelevant. However, in some medium and large vehicles, signal distortion (waveform sagging) increases as the number of high-speed can communication controllers increases. ), The controller misunderstands the signal.

An example of signal misrecognition according to signal distortion of high-speed can communication will be described as an example.

As shown in FIG. 2, the controller recognizes data (high '0' or low '1') in units of 2 ms, and transmits after transmitting a can signal ('0' = 2V or '1' = 0V). Immediately check whether the values match.

The controller recognizes the signal at a signal recognition point within one bit (1 bit = 2 ms), and determines the data by the voltage value at this signal recognition point (75%).

At this point, it is desirable to recognize the signal at the second half of the bit, i.

For example, it transmits data '0' (actual analog signal 2V) and checks whether the transmitted data is '0'.

If the transmitted data is '0' as shown in FIG. 3 and the received data value is '1' because the signal is distorted due to excessive capacitor capacity inside the controller at a point (50%) within 1 bit, the transmitted controller Determines that it is an error and immediately sends an error frame to all controllers.

In other words, if a controller transmits the voltage at 2V ('0') and then checks the received voltage and the signal is recognized as 0V ('1') due to signal distortion, it is treated as an error.

Due to such a signal misrecognition, there is a problem that the reliability of the high-speed can communication during the control period is lowered and the vehicle performance cannot be guaranteed.

The present invention has been invented to solve the above problems, and by recognizing the signal distortion for each controller, and automatically adjusts the optimum capacitor capacity according to the signal distortion, thereby satisfying the electromagnetic noise removal and can signal distortion prevention at the same time It is an object of the present invention to provide a method for reducing high-speed can signal distortion.

In order to achieve the above object, a method for reducing high-speed can signal distortion according to the present invention includes: checking whether the signal is distorted and the degree of distortion for each controller; Selecting an optimal capacitor capacity without signal distortion according to the signal distortion degree; And automatically adjusting the total capacitor capacity inside each controller to an optimum capacitor capacity, and by reducing the signal distortion by adjusting the capacitor capacity according to the signal distortion of each controller, it is possible to secure reliability of vehicle communication. It is characterized by being.

In particular, determining whether the signal is distorted and the degree of distortion comprises: determining whether the signal is distorted based on whether a value received after transmitting the can signal matches the transmitted value; Setting a plurality of signal recognition points within one bit and determining whether the signal is distorted when the signal is recognized at each signal recognition point of one preset bit; And determining a degree of signal distortion for each controller according to whether the signal distortion of each signal recognition point occurs.

The signal recognition point may be set at a time interval within the range of 1 to 75% for the entire recognition interval of 1 bit.

The optimum capacitor capacity is selected according to a signal recognition point at which signal distortion occurs.

In order to automatically adjust the total capacitor capacity to the optimum capacitor capacity, a plurality of capacitors connected in parallel and a plurality of transistors to be adjusted to the optimum capacitor capacity by turning the capacitors individually on and off do.

The advantages of the fast can signal distortion reduction method according to the present invention are as follows.

1. After checking the signal distortion and the degree of distortion through signal recognition at each point of 1 bit for each controller, if there is no signal distortion, it can remove the electromagnetic noise introduced from the outside by increasing the capacity of the capacitor, and the signal distortion In this case, by setting the capacitor's capacity low, signal distortion can be reduced, thereby improving the reliability of each communication period can communication signal.

2. The performance of the vehicle can be secured by selecting the optimum capacitor capacity under different conditions.

1 is a schematic diagram showing the network configuration of a typical high speed can communication
2 is a schematic diagram for explaining a can communication signal recognition method.
3 is a schematic diagram illustrating a conventional can communication signal misrecognition example
Figure 4 is a schematic diagram for explaining the step of checking whether the can communication signal misrecognition according to the present invention
5 is a circuit diagram for reducing can signal distortion according to an embodiment of the present invention.
6 is a flowchart of a method for reducing can signal distortion according to an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains (hereinafter, referred to as the person skilled in the art) may easily implement the present invention. .

Figure 4 is a schematic diagram for explaining the step of checking whether the can communication signal misrecognition according to the present invention, Figure 5 is a circuit diagram for reducing the can signal distortion according to an embodiment of the present invention, Figure 6 is the present invention A flowchart of a method for reducing can signal distortion according to an embodiment of the present invention.

In the present invention, to prevent distortion of the can signal described in the background art, it is impossible to apply a capacitor of small capacity unconditionally, and in order to remove electromagnetic noise or exceed the prescribed capacitor capacity (less than 100 Hz) or almost at a prescribed level No way.

In this situation, it is necessary to select the optimal capacitor capacity that can simultaneously remove the electromagnetic noise and can signal distortion.

The present invention recognizes the degree of distortion of the high-speed can communication signal for each controller, and then automatically adjusts the optimal capacitor capacity to prevent signal distortion, thereby eliminating electromagnetic noise and can signal distortion at the same time high speed can communication signal distortion It relates to a reduction method.

First, in order to automatically adjust the capacitor capacity inside the controller, it is necessary to select an optimal capacitor capacity that can satisfy both electromagnetic noise removal and can signal distortion prevention.

For this purpose, it is necessary for the controller to accurately determine whether the can signal is distorted and the degree of distortion.

The method for reducing can signal distortion according to an embodiment of the present invention includes determining whether the can signal is distorted and the degree of distortion for each controller at IGN ON or startup (S110, S120 to S140), and signal distortion after checking whether the signal is distorted. Selecting the optimum capacitor capacity according to the degree, and after the capacitor capacity selection step of automatically adjusting the overall capacitor capacity (S121 ~ 151).

First, the step of checking whether the can signal is distorted will be described.

In the can signal distortion checking step, as shown in FIG. 4, a signal recognition point of 1 bit is preset at predetermined intervals, and the signal is recognized at a predetermined signal recognition point to determine whether the signal is distorted.

For example, the signal recognition point may be set to 20%, 40%, and 60% points of one bit.

Here, the 20% point of one bit is the point where 20% of the start point (0 ms) of one bit (= 2 ms) becomes the last 0.4 ms (= 2 ms × 20%), and the remaining 40% and 60% points Also refers to the point calculated in the same way.

According to the method for checking the can signal distortion, if an error frame does not occur when the signal is recognized at 20% of one bit, it is determined that the signal distortion is small (S120, S121).

Second, when an error frame is generated when the signal is recognized at 20% of one bit, and an error frame is not generated when the signal is recognized at the 40%, it is determined that the signal distortion is normal (S130 and S131).

Third, when an error frame occurs when the signal is recognized at 40% of the 1-bit, and no error frame occurs when the signal is recognized at the 60%, it is determined that the signal distortion is severe (S140, S141).

Fourth, if an error frame occurs when the signal is recognized at 60% of 1 bit, it is determined that the signal distortion is very severe (S151).

In summary, the method for determining whether a can signal is distorted determines the degree of signal distortion by whether an error frame occurs when a signal is recognized at each point of 1 bit.

In the above description, the signal recognition point may be designated as 20%, 40%, 60%, but as another example, 10%, 20%, 30%, 40%, 50%, or the like.

Next, the step of selecting the optimum capacitor capacity according to the degree of signal distortion will be described.

The optimal capacitor capacity refers to the minimum capacitor capacity that can satisfy electromagnetic noise removal and signal distortion prevention at the same time.

First, when there is no signal distortion at 20% of 1 bit, the capacitor capacity is selected as 90 Hz (S121).

Second, when signal distortion occurs at 20% of one bit and no signal distortion occurs at 40%, the capacitor capacity is selected as 60 Hz (S131).

Third, when signal distortion occurs at 40% of one bit and no signal distortion occurs at 60%, the capacitor capacity is selected as 30 Hz (S141).

Fourthly, when signal distortion occurs at 60% of one bit, the capacitor capacity is selected as 10 Hz (S151).

Next, the steps of automatically adjusting the capacitor capacity after selecting the optimum capacitor capacity will be described.

The method of automatically adjusting the capacitance of the capacitor may automatically adjust the total capacitor capacity using a plurality of capacitors and transistors.

Referring to the circuit diagram for reducing the can signal distortion according to the present invention.

The vehicle CPU 10 and the CAN bus 12 are connected by two communication lines 16, and convert the TX and RX signals into can high and can low signals between the CPU 10 and the CAN bus 12. The high speed CAN transceiver 11 is disposed.

In addition, the A controller 13, the B controller 14, the C controller 15, and the like are connected to the can high line and the can low line of the can bus 12, and each controller 13 to 15 includes an EMS, a TCU, It may be any one of 4WD, ESP, cluster, SAS, ACC, ECS, EPB, and AFLS, but is not limited to such a controller.

Here, four capacitors C1, C2, C3, and C4 are connected in parallel to two communication lines 16 connecting the CPU 10 and the CAN bus 12 to implement a logic according to an embodiment of the present invention. And a plurality of transistors TR1, TR2, TR3, and TR4 are connected between the CPU 10 and the capacitors C1, C2, C3, and C4, respectively, and the capacitors C1, C2, C3, Power can be applied to C4).

For example, the first to third capacitors C1, C2, and C3 may each have a capacity of 30 μs, and the fourth capacitor C4 may have a capacity of 10 μs.

A method of automatically adjusting the total capacitor capacity through the logic implemented as described above is as follows.

First, if there is no signal distortion at 20% of one bit, the capacitor capacity is set to 90 Hz, and then the first to third transistors TR1, TR2, and TR3 are turned on to adjust the total capacitor capacity to 90 Hz. (Total capacitor capacity C = C1 + C2 + C3) (S121).

Second, when signal distortion occurs at 20% of one bit and no signal distortion occurs at 40%, the capacitor capacity is set to 60 Hz, and then both first and second transistors TR1 and TR2 are turned on. Adjust the total capacitor capacity to 60 Hz (total capacitor capacity C = C1 + C2) (S131).

Third, when signal distortion occurs at 40% of one bit and no signal distortion occurs at 60%, the capacitor capacity is set to 30 mV, and the first transistor TR1 is turned on to turn the entire capacitor capacity to 30 mV. (Total capacitor capacity C = C1) (S141).

Fourth, if signal distortion occurs at 60% of one bit, select the capacitor capacity as 10㎊, and turn on the fourth transistor TR4 to adjust the total capacitor capacity to 10㎊ (total capacitor capacity C = C4) (S151).

Therefore, according to the present invention, after checking the signal distortion and the degree of distortion through signal recognition at each point of 1 bit for each controller, if there is no signal distortion, it is possible to remove the electromagnetic noise introduced from the outside by increasing the capacitor capacity. In addition, when there is a signal distortion, the capacitance of the capacitor is set low to reduce the signal distortion, thereby improving reliability of each can communication signal.

In addition, it is possible to secure the performance of the vehicle by selecting the optimum capacitor capacity under different conditions of the number of controllers applied to each vehicle type.

1: can high line 2: can low line
10: CPU 11: High Speed CAN Transceiver
12: CANBUS 13 ~ 15: A controller, B controller, C controller
16: communication line
TR1, TR2, TR3, TR4: first to fourth transistors
C1, C2, C3, C4: first to fourth capacitors

Claims (5)

Checking whether the signal is distorted and the degree of distortion for each controller;
Selecting an optimal capacitor capacity without signal distortion according to the signal distortion degree; And
Automatically adjusting the total capacitor capacity inside each controller to an optimum capacitor capacity;
A high-speed can signal distortion reduction method, characterized in that consisting of.
The method according to claim 1,
The determining of whether the signal is distorted and the degree of distortion may include determining whether the signal is distorted based on whether a value received after transmitting the CAN signal coincides with the transmitted value;
Setting a plurality of signal recognition points within one bit and determining whether the signal is distorted when the signal is recognized at each signal recognition point of one preset bit; And
Determining a degree of signal distortion for each controller according to whether or not signal distortion occurs at each signal recognition point;
A high-speed can signal distortion reduction method, characterized in that consisting of.
The method according to claim 2,
The signal recognition point is a high-speed can signal distortion reduction method characterized in that the time interval is set in the range of 1 ~ 75% for the entire recognition interval of 1 bit.
The method according to claim 1,
And the optimal capacitor capacity is selected according to a signal recognition point at which signal distortion occurs.
The method according to claim 1,
In order to automatically adjust the total capacitor capacity to the optimum capacitor capacity, a plurality of capacitors connected in parallel and a plurality of transistors to be adjusted to the optimum capacitor capacity by turning the capacitors individually on and off Fast can signal distortion reduction method.

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