KR102149204B1 - Method of fault response for steer-by-wire system - Google Patents

Abstract

The present invention relates to a failure response method of an SBW system, comprising: an SBW system failure determination step of determining whether the SBW system has a failure; If it is determined as a failure in the SBW system failure determination step, the first failure response step corresponding to the failure primarily; A continuity determination step of determining whether or not the fault condition is continuous after the first failure response step; If it is determined that there is continuity of the failure condition in the failure condition continuity determination step, a final failure response step corresponding to the failure is finally included. Accordingly, the reliability of the failure response method of the SBW system can be enhanced.

Description

SBW system failure response method {METHOD OF FAULT RESPONSE FOR STEER-BY-WIRE SYSTEM}

The present invention relates to a failure response method of an SBW system, and more particularly, to a failure response method of an SBW system capable of responding to a failure situation of the SBW system.

In general, the SBW (Steer-By-Wire) system is one of the next-generation steering systems that have been electronically converted by removing various connecting devices mechanically connected between the steering wheel and the wheels.

Electronicization of the SBW system is achieved through various sensors and motors.

In particular, since the SBW system may not be able to steer by the steering wheel when a failure occurs, a quick response is required, and in support of this, research on a failure response method is actively being conducted.

In the conventional SBW system, a failure response method is to determine whether a sensor or a motor mounted on a column has a failure, and when a failure occurs, a separate mechanical failure response system is converted. In other words, when a failure of a sensor or motor mounted on a column is confirmed in real time, the failure response system (hardware and software) is operated to ensure stability. A U/Joint type clutch is used as a failure response system.

However, the failure response method of the SBW system as above simply judges whether the sensor or motor installed in the column has failed, and applies a uniform failure response system regardless of the failure situation (the cause of the failure), thereby responding to the failure of the SBW system. There is a problem in that time and economic costs are relatively large. For example, the same fault response system is applied to simple faults (one-time faults) such as simple faults of the sensor itself, rather than a serious fault of the SBW system itself (a fault with continuity).

In addition, as the frequency of response of the failure response system is increased, there is a disadvantage of inferior durability.

This, in turn, results in lowering the reliability of the failure response method of the SBW system.

The present invention has been conceived to solve the above problems, and the problem to be solved in the present invention is of the SBW system that can individually respond by determining the failure situation as well as the occurrence of failure of a sensor or motor mounted on a column. It is to provide a fault response method.

The failure response method of the SBW system according to the present invention for solving the above problems includes: an SBW system failure determination step of determining whether the SBW system has failed; A first failure response step corresponding to the failure first when it is determined as a failure in the SBW system failure determination step; A continuity determination step of determining the continuity of the fault condition after the first failure response step; If it is determined that there is continuity of the failure situation in the determination step of continuity of the failure situation, a final failure response step corresponding to the failure is finally included, and there is a technical feature thereof.

The failure response method of the SBW system according to the present invention can appropriately respond to the failure situation of the SBW system, thereby further improving the efficiency of the failure response of the SBW system.

In addition, it is possible to relatively reduce the time and economic costs associated with the failure response of the SBW system.

Therefore, the reliability of the failure response method of the SBW system can be further enhanced.

1 is a block diagram of an SBW system according to the present invention,
2 is a flowchart sequentially showing a method for responding to a failure of an SBW system according to the present invention;
3 is a block diagram showing a failure determination algorithm of the SBW system according to the present invention;
4 is a flow chart showing a steering torque failure determination algorithm of the SBW system according to the present invention;
5 is a flow chart showing a steering angle failure determination algorithm of the SBW system according to the present invention;
6 is a photograph showing an input signal when the sensor or motor of the SBW system according to the present invention is normal/failed.

Hereinafter, a method for coping with the failure of the SBW system according to the present invention will be described in detail through the drawings.

First, the SBW (Steer-By-Wire) system according to the present invention includes a steering reaction force unit 10, an electronic control unit 20, and a steering drive unit 30, as shown in FIG. 1.

The steering reaction force unit 10 includes a steering wheel 12; A column 14 connected to the lower end of the steering wheel 12; A sensor 16 mounted on the column 14; It is configured to include a motor 18 mounted on the column 14.

The steering wheel 12 is rotated, and the column 14 stably supports the steering wheel 12.

The sensor 16 is for determining the driver's steering will. Such a sensor 16 detects an angle sensor 16a that detects a steering angle through a change in rotation of the column 14, which varies according to the steering of the steering wheel 12, and detects the steering torque according to the rotational motion of the column 14. It consists of a torque sensor (16b).

The motor 18 generates a force in a direction opposite to the rotation of the steering wheel 12 according to a signal applied from the electronic control unit 20 to provide an appropriate steering feel to the driver.

In addition, as a component of the steering reaction force unit 10, a speed reducer (not shown) for appropriately controlling the rotational force speed of the motor 18 may be additionally installed.

The electronic control unit 20 operates the motor 18 by receiving signals measured by the sensor 16 of the steering reaction force unit 10, that is, the angle sensor 16a and the torque sensor 16b in real time, and operates the wheel. A signal for driving the steering drive unit 30 that operates 40 is generated and transmitted.

In particular, when a failure occurs in at least one of the steering reaction force unit 10 and the steering drive unit 30, the electronic control unit 20 has a function of recognizing and determining the failure situation and responding to it.

A detailed description of the failure response method of the SBW system will be described later.

The steering drive unit 30 includes a motor 32; Rack bar 34 driven by the power generated from the motor 32; A sensor 36 measuring the displacement of the rack bar 34; It consists of a tie rod 38 connected between the rack bar 34 and the wheel 40.

The motor 32 is driven by a signal transmitted from the electronic control unit 20, and the sensor 36 provides the measured displacement of the rack bar 34 to the electronic control unit 20. And the rack bar 34 and the tie rod 38 serve to stably transmit the steering force by the motor 32 to the wheel 40.

Meanwhile, reference numeral 19, which is not described, denotes a toothed belt connected between the column 14 and the motor 18.

When a failure occurs in the SBW system described above, a response method will be sequentially described as follows.

As shown in Figure 2, the failure response method of the SBW system according to the present invention, SBW system failure determination step (S10); The first failure response step (S20); Determining the continuity of the failure situation (S30); Final failure response step (S40); It is configured to include the SBW system steering control step (S50).

① SBW system failure determination step (S10): This is a step to determine whether the SBW system is malfunctioning through the presence or absence of an abnormality in the sensors (16, 36) and/or motors (18, 32) mounted on the column (14).

In the SBW system failure determination step (S10), the change in the output signal output from the sensors 16 and 36 and/or the motors 18 and 32 is determined whether or not there is an abnormality in the sensors 16 and 36 and/or the motors 18 and 32. The trend is periodically checked through the electronic control unit 20 and determined in real time. For example, when the output values of the sensors 16 and 36 and/or the motors 18 and 32 deviate from the predicted output values or do not change for a certain period of time, it is determined that there is an abnormality and recognized as a failure.

On the other hand, the entire algorithm for determining the failure of the SBW system, as shown in Fig. 3, through the steering torque failure determination algorithm, the steering angle failure determination algorithm, and the motor RPM change, the sensor (16, 36) and/or the motor ( 18, 32) is determined to have a failure, and if it is normal, a target current motor is applied, and in case of a failure, a low current motor is applied to control the rack bar 34.

As shown in Fig. 4, the above steering torque failure determination algorithm monitors the steering torque value detected by the torque sensor every 10 ms, and then continuously compares the monitored steering torque value with the previous steering torque value. If the difference between the steering torque value and the previous steering torque value is greater than 3Nm, the result value is converted to 1, and if it is less than 3Nm, the result value is converted to 0. If the sum of the converted result values is greater than 1, it is considered a malfunction. In addition, if it is less than 1, it is determined as normal, and a malfunction is determined by monitoring the steering torque value detected through the torque sensor every 30ms, and the determination result is output as 1 or 0. As shown in FIG. 5, the steering angle failure determination algorithm monitors the steering angle value detected by the angle sensor at 10 ms intervals, and then continuously compares the monitored steering angle value with the previous steering angle value. If the difference between the degree value and the previous steering angle value is greater than 3deg, the result value is converted to 1, and if it is less than 3deg, the result value is converted to 0. If the sum of the converted result values is greater than 1, it is considered a malfunction. In addition, if it is less than 1, it is determined as normal, and a malfunction is determined by monitoring the steering angle value detected through the angle sensor every 30 ms, and the determination result is output as 1 or 0. Such a steering torque/steering angle failure determination algorithm can be variously changed within a range that can increase the efficiency of failure determination.

② First failure response step (S20): If it is determined that it is a failure in the SBW system failure determination step (S10), it is a step that primarily responds to the failure.

In this first failure response step (S20), a response to a simple failure such as a one-time failure is made. For example, when a problem occurs in the sensor itself due to instability (short circuit, measurement error, etc.) around and inside the SBW system, a response is made to a failure.

③ Determining whether the failure situation is continuity (S30): This is the step of determining whether the failure situation is continuity after the first failure response step (S20).

In the determination step (S30) of whether the failure situation is continuity, it is determined whether the SBW system does not return to the normal state and the failure situation continues despite the response of the first failure response step (S20), and the SBW system It is possible to respond by accurately judging the fault condition of.

④ Final failure response step (S40): If it is determined that there is continuity of the failure situation in the failure situation continuity determination step (S30), it is a step to finally respond to the failure.

In the final failure response step (S40), the failure of the SBW system is recognized as a serious state, and the failure response system (hardware and software) is operated accordingly to ensure stability.

⑤ SBW system steering control step (S50): When the fault is finally repaired through the final fault response step (S60), the steering reaction force unit 10, electronic control unit 20, and steering drive unit 30 of the SBW system This is the step of controlling the steering of the vehicle.

In the above first failure response step (S20) and the final failure response step (S40), it is possible to minimize the effort for failure response by individually applying different known failure response systems suitable for the failure situation. Economic cost can be relatively reduced.

On the other hand, if it is determined that the SBW system is normal in the SBW system failure determination step (S10), the steering reaction force unit 10, the electronic control unit 20, and the steering drive unit 30 as in the SBW system steering control step (S50). The operation proceeds to the normal SBW system steering control step S60 for controlling the steering of the vehicle.

6 shows an input signal scenario when the sensor or motor of the SBW system according to the present invention is normal/failed. When a total of 6 errors are detected in the signal input to the electronic control unit 20, it is determined as a primary failure. The response is made through the vehicle failure response step (S20), and if a failure situation occurs continuously, the response is finally performed through the final failure response step (S40).

10: column 20: sensor
30: Motor S10: SBW system failure determination step
S20: primary failure response step S30: continuity determination step of the failure situation
S40: Final failure response step

Claims (4)

In the SBW system consisting of a steering reaction force unit, an electronic control unit, and a steering drive unit,
SBW system failure determination step of determining whether the SBW system has failed;
A first failure response step corresponding to the failure first when it is determined as a failure in the SBW system failure determination step;
A continuity determination step of determining whether the fault condition is continuous through whether the SBW system does not return to a normal state and the fault condition continues despite the response of the first failure response step;
If it is determined that there is a continuity of the failure condition in the failure condition continuity determination step, a final failure response step finally corresponding to the failure is included,
An angle sensor that detects a steering angle through a rotation change of a column of the steering reaction force unit, and a change in an output signal of a torque sensor that detects steering torque according to the rotational motion of the column is periodically checked and input to the electronic control unit. If an error is detected in the signal, it is determined as a primary failure and responds through the first failure response step, and if a failure situation occurs continuously, it finally responds through the final failure response step to reduce the frequency of failure response.
The steering torque failure determination algorithm monitors the steering torque value detected by the torque sensor every 10 ms, and then continuously compares the monitored steering torque value with the previous steering torque value, and the monitored steering torque value and the previous steering If the difference in torque value is greater than 3Nm, the result value is converted to 1, and if it is less than 3Nm, the result value is converted to 0. If the sum of the converted result values is greater than 1, it is judged as a malfunction. It is determined as normal, and after determining malfunction by monitoring the steering torque value detected through the torque sensor every 30ms, the determination result is output as 1 or 0,
The steering angle failure determination algorithm monitors the steering angle value detected by the angle sensor every 10 ms, and then continuously compares the monitored steering angle value with the previous steering angle value, and the monitored steering angle value and the previous steering angle If the difference between the degree values is greater than 3deg, the result value is converted to 1, and if it is less than 3deg, the result value is converted to 0. If the sum of the converted result values is greater than 1, it is judged as a malfunction. The failure response method of an SBW system, characterized in that the determination result is output as 1 or 0 after determining that it is normal and determining a malfunction by monitoring a steering angle value detected through the angle sensor every 30 ms. delete delete delete

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