KR20190085316A - Fail Safe Apparatus For Electric Power Steering System And Method Thereof - Google Patents

Abstract

The present invention relates to a failsafe apparatus for an electric power steering system and a method thereof which continuously provide steering assist power. The failsafe apparatus for an electric power steering system comprises: an information collection unit to collect assist current information of a steering motor supplying steering assist power, and collect target steering information and driving information in accordance with a steering input of a driver; a current calculation unit to calculate a target current based on the target steering information; an abnormality determination unit to determine an abnormality of a steering control apparatus based on the target current and the assist current information; an initialization determination unit to determine whether to execute initialization of the steering control apparatus based on the collected target steering information and driving information; a control unit to generate an initialization execution signal to command the initialization execution and a current control signal to apply a limit current to the steering motor; and an output unit to output the generated signals to the steering control apparatus, and output a warning signal.

Description

(Fail Safe Apparatus for Electric Power Steering System and Method Thereof)

The present invention relates to fail safe devices and methods for controlling the operation of an electric power steering system in the event of an error in devices constituting an electric power steering system.

2. Description of the Related Art Generally, an electric power steering system (EPS) is installed in a vehicle to reduce the steering force of a steering wheel (steering wheel) to assure the stability of a steering state. The steering force of the driver is made easy.

In other words, steering control is a control for generating an auxiliary steering force for assisting the steering force of the driver. Therefore, stability, reliability, and the like must be ensured because steering performance may be degraded or an accident may be caused when a malfunction occurs.

Therefore, since motor control is essential to realize this, various types of components such as sensors, ECUs, and motors are installed in the electric power steering system (EPS), and the position, speed, and torque of the steering motor can be controlled.

In this case, when the reliability of the mounted parts is not ensured due to one error or the like, there is a problem that the steering assist force is lost or the steering control itself is not performed. This causes a serious driving accident .

Therefore, when an error is detected in the conventional electric power steering system (EPS), the steering assist force is temporarily lost by stopping the operation of the steering motor regardless of the degree of error.

However, if the generated error is an erroneous detection or a single error, the stop of the steering motor may become an unnecessary operation, thereby causing an uncomfortable feeling in running and giving a great sense of heterogeneity to the operation of the steering wheel of the driver.

In addition, as the autonomous vehicle is developed, the fail safe device of the electric power steering system (EPS) is required to have high reliability, and thus a fail safe device capable of actively responding to various error occurrence situations is required.

In order to solve the above problems, there is provided a fail-safe apparatus and method for an electric power steering system in which an output of an assist current of a motor is controlled by determining an error state when an error occurs in the electric power steering system.

The present invention also provides a fail-safe apparatus and method for continuously providing a steering assist force by initializing a control apparatus of an electric power steering system in accordance with an error state even when an error occurs in an electric power steering system.

According to an aspect of the present invention, there is provided a fail-safe system for an electric power steering system, comprising: a steering angle sensor for collecting assistance current information of a steering motor for supplying a steering assist force, An abnormality determination unit for determining an abnormality of the steering control device on the basis of the target current and the assist current information, an abnormality determination unit for determining an abnormality of the steering control device based on the target current and the assist current information, An initialization determination unit for determining whether to execute initialization of the steering control apparatus based on the target steering information and the running information, an initialization execution signal for instructing the initialization execution, and a current control signal for applying a limiting current to the steering motor And outputs the control signal and the generated signal to the steering control device, Power output may include a to.

According to another aspect of the present invention, there is provided a fail safe method for an electric power steering system, comprising: acquiring assist current information of a steering motor for supplying a steering assist force; An abnormality determination step of determining an abnormality of the steering control device based on the target current and the assist current information, a step of calculating a target current based on the target current and the assist current information, An initialization determining step of determining whether to execute initialization of the steering control device on the basis of the collected target steering information and the traveling information, an initialization execution signal for instructing the initialization execution, and a current control signal for applying a limiting current to the steering motor And outputting the generated signal to the steering control device And, it may include an output step of outputting a warning signal.

Other specific details of the invention are included in the detailed description and drawings.

As described above, according to the present invention, when an error occurs in the electric power steering system, the steering assist force of the vehicle is controlled according to the error state, thereby reducing the sense of heterogeneity in the steering operation.

Further, even when an error occurs, the electric power steering system operates normally, so that reliability and running stability are improved.

1 is a block diagram of a part of an electric power steering system including a fail safe device according to an embodiment of the present invention.
2 is a block diagram of a fail-safe system of an electric power steering system according to an embodiment of the present invention.
3 is a flowchart illustrating a fail-safe method of an electric power steering system according to an embodiment of the present invention.
4 is a flowchart illustrating a fail-safe method of an electric power steering system according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Although the first, second, etc. are used to describe various elements, components and / or sections, it is needless to say that these elements, components and / or sections are not limited by these terms. These terms are only used to distinguish one element, element or section from another element, element or section. Therefore, it goes without saying that the first element, the first element or the first section mentioned below may be the second element, the second element or the second section within the technical spirit of the present invention.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, the terms "comprises" and / or "made of" means that a component, step, operation, and / or element may be embodied in one or more other components, steps, operations, and / And does not exclude the presence or addition thereof.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block diagram of a part of an electric power steering system 1 including a fail safe device according to an embodiment of the present invention.

Referring to FIG. 1, an electric power steering system 1 according to an embodiment of the present invention includes a steering wheel, a motor 110 for generating a steering assist force according to an operation of the steering wheel, a motor 110, A steering control device 130 that controls various operations of the electric power steering system 1, a steering control device 130 that controls various operations of the electric power steering system 1, an electronic control unit (ECU) A fail-safe device 120 for detecting an abnormality of the steering control device 130 and controlling the operation of the steering control device 130, a steering angle sensor 140 for sensing the steering angle of the steering wheel, A torque sensor 150 for sensing a steering force applied to the vehicle, a vehicle speed sensor 160 for sensing the speed of the vehicle, and the like.

Here, the motor 110 may generate the steering assist force in accordance with the control signal received from the electronic control means (ECU) 130 and the fail-safe device 120. [

Specifically, the electronic control unit (ECU) 130 can calculate the target steering torque value from the predetermined assist control map based on the signals output from the steering angle sensor 140 and the torque sensor 150. [ The control signal according to the target steering torque value, that is, the assist current signal, can be applied to the motor 110.

The fail safe device 110 determines whether or not the electronic control unit (ECU) 130 is abnormal based on the signals output from the steering angle sensor 140 torque sensor 150 and the vehicle speed sensor 160, Can be controlled.

In addition, the fail-safe device 110 can be activated based on a failure signal output from an ECU of various systems provided in the vehicle through in-vehicle communication.

That is, not only the electric power steering system 1 but also the fail safe device 110 can be operated in the event of occurrence of one or more system faults in the vehicle, thereby improving the running stability of the vehicle.

In addition, the fail safe device 110 may be included in the steering control device 130 as shown in FIG. 1, but may not be included in the steering control device 130, but may be an organically connected device.

Here, a part of the electric power steering system 1 shown in Fig. 1 is merely an example, but is not limited thereto.

2 is a block diagram of the fail safe device 120 of the electric power steering system 1 according to the embodiment of the present invention.

2, the fail safe device 120 of the electric power steering system 1 according to the embodiment of the present invention collects the assist current information of the steering motor 110 that supplies the steering assist force, A target current calculation unit 220 for calculating a target current based on the target steering information, a steering angle sensor 220 for detecting steering angle based on the target current and the assist current information, An abnormality determination unit 230 for determining abnormality of the control device 130, an initialization determination unit 240 for determining whether to execute initialization of the steering control device 130 based on the collected target steering information and the travel information, A control unit 250 for generating an initialization execution signal for instructing the initialization execution and a current control signal for applying a limiting current to the steering motor 110, and a control unit 130 for outputting the generated signal to the steering control unit 130 And it may include an output section 260 for outputting a warning signal.

Specifically, the information collecting unit 210 may collect the assist current applied to the steering motor 110 from the electronic control unit (ECU), and may transmit the assist current to the abnormality determiner 230.

The information collecting unit 210 may sense the steering angle, which is the target steering information according to the steering input of the driver, from the steering angle sensor 140, and sense the steering torque as the target steering information from the torque sensor 150. In addition, the information collecting unit 210 may collect the driving information through various sensors provided in the vehicle, such as the vehicle speed sensor 160.

In addition, the information collecting unit 210 of the fail safe device 120 included in the electric power steering system (EPS) 1 receives the steering angle sensor 140 through a serial communication (serial communication) such as SPI (Serial Programming Interface) , The torque sensor (150), and the vehicle speed sensor (160).

Therefore, the information collecting unit 210 may transmit the collected target steering information to the current calculating unit 220 and the initialization determining unit 240, and may transmit the traveling information to the initializing determiner 240. [

In addition, the information collecting unit 210 may collect a failure signal from at least one ECU (Electronic Control Unit) provided in the vehicle.

For example, when a failure is detected in the ECU of the automatic emergency braking system (AEB), the failure signal can be transmitted to the information collecting unit 210 through in-vehicle communication. Alternatively, the information collecting unit 210 can collect a failure signal from an ECU such as a braking device or an accelerator.

The current calculation unit 220 may calculate the target current based on the steering angle or the steering torque, which is the target steering information. At this time, the target current is a current for outputting the steering assist force to the driver as the driver target, and the calculation method may be an operation method generally used in the art.

The abnormality determination unit 230 may determine that an abnormality has occurred in the steering control apparatus based on the failure signal collected by the information collection unit 210. [ That is, even when one or more system faults in the vehicle occur, the fail safe device 110 is operated to improve the running stability of the vehicle.

In addition, the abnormality determiner 230 may compare not only the failure signal but also the target current and the assist current information to determine that an abnormality has occurred in the steering controller 130 when an error current is generated. At this time, if the error current is equal to or higher than a predetermined threshold current, it can be determined that an abnormality has occurred.

Here, the error current may be a difference between the current value of the target current and the current value applied to the steering motor 110, which is the assist current information. That is, the error current may occur due to a failure in various sensors or circuit elements such as components constituting the electric power steering system (EPS) 1, for example, steering angle sensor 140, motor position sensor and the like.

The initialization determining unit 240 may determine whether the initialization is to be performed based on at least one of a vehicle speed as the running information, a steering torque as a target steering information, and a steering angle.

At this time, the initialization execution is an operation of resetting the information input to the steering control device 130, and can initialize the target current information corresponding to the target steering assist force.

The initialization determining unit 240 may determine whether the initialization is performed based on the steering torque or the steering angle when the vehicle speed is less than the critical speed.

At this time, the critical speed may be a predetermined value, and may be a speed of the vehicle determined to be free of an accident during initialization of the steering control device 130. [

The initialization determining unit 240 may determine the initialization execution so that the steering controller 130 is initialized when the steering torque is equal to or less than the threshold value or when the steering angle is equal to or less than the critical angle.

At this time, the threshold value and the critical angle may be a predetermined value, and may be a steered state of the vehicle, which is determined to be free of an accident during initialization of the steering control device 130.

The control unit 250 may generate the current control signal and the initialization execution signal when the initialization execution is determined.

Accordingly, the control unit 250 may calculate the limit current based on the target current, and may generate the current control signal that increases the limit current by a predetermined ratio.

At this time, the limiting current may have a current value smaller than the target current, and the output range of the limiting current may be preliminarily set to be gradually increased in a predetermined ratio in order to reduce the steering disturbance of the driver. Accordingly, the current control signal may be generated such that the limiting current is increased at a certain rate and applied to the steering motor 110. In addition, the magnitude of the limiting current can be limited and fixed by the assist map previously stored in the electronic control means (ECU) of the electric power steering system 1 (EPS).

Therefore, by outputting the limiting current signal to the steering motor 110, the driver can minimize the sense of heterogeneity during the steering operation.

The control unit 250 may generate a stop control signal for stopping the steering control unit 130 when the initialization execution is continuously performed or when the initialization execution count is a predetermined number of times or more.

That is, when the initialization execution occurs, the control unit 250 stores initialization occurrence information such as a generation start time and an initialization execution count in a memory (not shown), and generates the stop control signal Can be determined.

Since the stop control signal is a signal for stopping the operation of the steering control device 130 and does not apply a current to the steering motor 110, the steering assist force is 0, so that the steering assist force of the vehicle can be temporarily lost have.

The output unit 260 receives at least one of the current control signal, the initialization execution signal, and the stop control signal generated by the control unit 250 and outputs the received signal to the electronic control unit (ECU) of the steering control device 130 can do.

That is, when the output unit 260 outputs the current control signal and the initialization execution signal to the electronic control unit (ECU), the limiting current may be increased to a certain rate and applied to the steering motor 110.

On the other hand, when the output section 260 outputs the stop control signal to the electronic control means (ECU), the steering assist force of the vehicle may temporarily be lost.

Further, the output unit 260 may output the warning signal as at least one of an audible warning, a visual warning, and a tactile warning. At this time, the warning signal of the output unit 260 can be output to a display (not shown), an audio output module (not shown), an alarm module (not shown), a haptic module (not shown)

For example, the output unit 260 can output a visual warning signal or an audible warning signal to the cluster or head-up display of the vehicle to notify the driver of the failure message of the steering control device 130. [

As described above, the fail safe device 120 of the present invention can control the output of the assist current of the motor by determining the error state when an error occurs in the electric power steering system 1.

The present invention also provides a failsafe device (120) that continuously provides a steering assist force by initializing a control device of an electric power steering system in accordance with an error state even when an error occurs in the electric power steering system (1).

3 is a flowchart illustrating a fail-safe method of an electric power steering system according to an embodiment of the present invention.

3, the fail safe method of the electric power steering system according to the embodiment of the present invention collects the assist current information of the steering motor for supplying the steering assist force, and obtains target steering information based on the steering input of the driver, (S300) for collecting driving information, a current calculating step (S310) for calculating a target current based on the target steering information, an abnormality of the steering control device based on the target current and the assist current information An initialization determining step S330 of determining whether to execute the initialization of the steering control device based on the collected target steering information and the traveling information, an initialization execution signal for instructing the initialization execution, A control step (340) of generating a current control signal for applying a limiting current to the motor, and a control step Output, and it may include an output step (S350) for outputting a warning signal.

Specifically, in the information gathering step S300, the steering angle, which is target steering information according to the steering input of the driver, is sensed from the steering angle sensor, and the steering torque, which is the target steering information, is sensed from the torque sensor. In addition, the driving information can be collected through various sensors provided in the vehicle, such as the vehicle speed sensor 160.

In addition, in the information collection step S300, a failure signal can be collected from at least one ECU provided in the vehicle.

In the current calculation step S310, the target current may be calculated based on the steering angle or the steering torque, which is the target steering information.

If the error current is generated by comparing the target current and the assist current information in the abnormality determination step (S320), it can be determined that an abnormality has occurred in the steering control device.

In addition, it can be determined that an abnormality has occurred in the steering control device based on the failure signal collected in the abnormality determination step S320.

In the initialization decision step S330, it is possible to determine whether or not the initialization is performed based on at least one of the vehicle speed as the running information, the steering torque as the target steering information, and the steering angle.

That is, in the initialization determination step S330, the initialization execution may be determined so that the steering control device is initialized when the vehicle speed is equal to or less than the critical speed, the steering torque is equal to or less than the threshold value, or the steering angle is equal to or less than the critical angle.

In the control step S340, if the initialization execution is determined, the current control signal and the initialization execution signal can be generated.

Also, in the control step S340, a stop control signal for stopping the steering control device may be generated when the initialization execution is continuously performed or when the number of times of the initialization execution is a certain number of times or more.

In the output step S350, at least one of the current control signal, the initialization execution signal, and the stop control signal generated by the control unit 250 is received and output to the electronic control means (ECU) of the steering control device have.

In the output step S350, the warning signal may be output as at least one of audible warning, visual warning, and tactile warning. At this time, the warning signal of the output unit 260 can be output to a display (not shown), an audio output module (not shown), an alarm module (not shown), a haptic module (not shown)

4 is a flowchart illustrating a fail-safe method for an electric power steering system according to an embodiment of the present invention.

Referring to FIG. 4, assist current information of the steering motor is collected (S400), and target steering information and driving information are collected (S410). In addition, a fault signal is collected from at least one ECU provided in the vehicle.

Then, the target current is calculated based on the target steering information (S420).

Then, the target current is compared with the assist current information (S430), and it is determined whether an error current occurs or whether the failure signal is detected (S440).

That is, since the error current is a difference between the current value of the target current and the current value applied to the steering motor 110, which is the assist current information, It can be determined that an abnormality has occurred.

At this time, if the error signal is not detected or if the error current does not occur, the assist current information of the steering motor is collected again (S400), and the target steering information and driving information are collected again (S410).

On the other hand, if the error current occurs or the failure signal is sensed, it is determined that an abnormality has occurred in the steering control device (S450).

Then, a stop control signal for stopping the steering control device is generated and output (S54630).

Then, the steering control apparatus stops according to the stop control signal, and outputs a warning signal corresponding to the stop control signal (S470).

In step S4680, it is determined whether the initialization execution has been continuously performed in the steering control apparatus or whether the initialization execution has occurred N times or more.

At this time, in the case where the initialization execution is continuously performed in the steering control device or when the number of times of the initialization execution is N times or more, a stop control signal to stop the steering control device is generated and output (S530).

That is, since the current is not applied to the steering motor, the steering assist force becomes zero, and thus the steering assist force of the vehicle is temporarily lost.

On the other hand, if the initialization has not been continuously performed in the steering control device and the number of times of initialization is less than N times, it is determined in step S4790 if the vehicle speed as the running information is equal to or less than the threshold speed.

At this time, if the vehicle speed exceeds the critical speed, the assist control unit generates and outputs a stop control signal for stopping the steering control device continuously (S400). At the same time, the target steering information and the driving information are re- (S4610).

On the other hand, if the vehicle speed is less than or equal to the critical speed, it is determined whether the steering torque, which is the target steering information, is less than or equal to the threshold value or the steering angle is less than or equal to the critical angle (S50480).

At this time, if the steering torque exceeds the threshold value or the steering angle exceeds the critical angle, a stop control signal for stopping the steering control device is continuously generated and output (S460) Simultaneously with the step S400, the target steering information and the driving information are collected again (S410).

On the other hand, if the steering torque is equal to or less than the threshold value or the steering angle is equal to or less than the critical angle, the steering control device is determined to be initialized (S51490).

The limit current is calculated, which is based on the target current, and generates the current control signal to increase the limit current by a predetermined ratio (S5200).

At this time, the limiting current may have a current value smaller than the target current, and the output range of the limiting current may be preliminarily set to be gradually increased in a predetermined ratio in order to reduce the steering disturbance of the driver.

Generates the initialization execution signal, and outputs the initialization execution signal and the current control signal (S5130).

Then, the steering control device performs initialization according to the initialization execution signal (S530), and outputs a warning signal corresponding to the initialization execution signal (S5540).

That is, since the limiting current is increased at a certain rate and applied to the steering motor, the driver can minimize the sense of heterogeneity in the steering operation.

As described above, the failure-safe apparatus and method of the electric power steering system according to the present invention can reduce the sense of heterogeneity in the steering operation by controlling the steering assist force of the vehicle according to the error state when the electric power steering system is in error .

Further, even when an error occurs, the electric power steering system operates normally, so that reliability and running stability are improved.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or essential characteristics thereof. . The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

1: Electric power steering system (EPS)
110: motor
120: Fail-safe device of electric power steering system
130: Steering control device
140: Steering angle sensor 150: Torque sensor
160: vehicle speed sensor
210: information collecting unit 220: current calculating unit
230: abnormality determination unit 240: initialization determination unit
250: control unit 260: output unit

Claims (12)

An information collecting unit collecting assist current information of a steering motor for supplying a steering assist force and collecting target steering information and running information according to a steering input of a driver;
A current calculation unit for calculating a target current based on the target steering information;
An abnormality determination unit for determining an abnormality of the steering control device based on the target current and the assist current information;
An initialization determining unit for determining whether the steering control apparatus is initialized based on the collected target steering information and the running information;
A control unit for generating an initialization execution signal for instructing the initialization execution and a current control signal for applying a limiting current to the steering motor; And
And outputting the generated signal to the steering control device and outputting a warning signal. The method according to claim 1,
The information collecting unit,
A fail-safe device of an electric power steering system for collecting a failure signal from at least one ECU (Electronic Control Unit) provided in a vehicle. 3. The method of claim 2,
The abnormality determination unit
And determines that an abnormality has occurred in the steering control device based on the failure signal. The method according to claim 1,
The abnormality determination unit
And determines that an abnormality has occurred in the steering control device when an error current is generated by comparing the target current and the assist current information. The method according to claim 1,
The initialization determination unit may determine,
And determining whether the initialization is to be executed based on at least one of a vehicle speed as the running information, a steering torque as a target steering information, and a steering angle. 6. The method of claim 5,
The initialization determination unit may determine,
And determines whether or not the initialization is executed based on the steering torque or the steering angle if the vehicle speed is below the critical speed. The method according to claim 6,
The initialization determination unit may determine,
Wherein the initialization execution is determined so that the steering control apparatus is initialized when the steering torque is equal to or less than a threshold value or when the steering angle is equal to or less than a critical angle. The method according to claim 1,
Wherein,
And generates the current control signal and the initialization execution signal when the initialization execution is determined. The method according to claim 1,
Wherein,
Wherein the limit current is calculated on the basis of the target current and the current control signal for increasing the limiting current by a predetermined ratio is generated. The method according to claim 1,
Wherein,
And generates a stop control signal for stopping the steering control device when the initialization execution is continuously performed or when the number of times of the initialization execution is a predetermined number of times or more. The method according to claim 1,
The output unit includes:
And outputs the warning signal as at least one of an audible warning, a visual warning, and a tactile warning. An information collecting step of collecting assist current information of a steering motor for supplying a steering assist force and collecting target steering information and running information according to a steering input of a driver;
A current calculating step of calculating a target current based on the target steering information;
An abnormality determination step of determining an abnormality of the steering control device based on the target current and the assist current information;
An initialization determining step of determining whether to execute initialization of the steering control device based on the collected target steering information and the traveling information;
A control step of generating an initialization execution signal for instructing the initialization execution and a current control signal for applying a limiting current to the steering motor; And
And outputting the generated signal to the steering control device and outputting a warning signal. ≪ RTI ID = 0.0 > [0002] < / RTI >

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