KR20170006066A - Apparatus and method for controlling active front steering system - Google Patents

Abstract

A control device for an active front wheel steering system of a vehicle according to an embodiment of the present invention includes: a planetary gear formed so that a gear ratio can be varied; A motor driven to vary a gear ratio of the planetary gear; And an electronic control unit for controlling the motor based on a signal detected by a vehicle speed sensor, a steering angle sensor and a pinion angle sensor, wherein when the electronic control unit determines that there is an abnormality in the steering angle signal transmitted from the steering angle sensor The driving of the motor is stopped, and the steering angle is again estimated to restart the motor.

Description

TECHNICAL FIELD [0001] The present invention relates to a control system for an active front wheel steering system of a vehicle,

[0001] The present invention relates to a control apparatus and method for an active front steering system (AFS) of a vehicle, and more particularly to a control system for an active front wheel steering system having a variable gear ratio (VGR) And a control method thereof.

The steering apparatus of the vehicle is a device for changing the traveling direction of the vehicle according to the will of the driver and is a device for assisting the driver to move the vehicle in a desired direction by arbitrarily changing the turning center of the front wheel. Recently, the steering shaft is separated so as to actively cope with the external environment such as a strong wind blowing on the road or an asymmetric road surface, so that the steer angle, which is generated by the driver's steering wheel operation, is not transmitted directly to the steering column, Called active front wheel steering system in which the steering angle is adjusted by sensing the steering angle continuously, comparing it with various kinds of information of the vehicle, and then transmitting it to the motor for controlling the steering shaft rotation of the steering column by an electrical signal.

In this active front wheel steering system, a planetary gear for converting the gear ratio between the input shaft and the output shaft is provided, and the steering angle according to the vehicle speed is controlled by varying the gear ratio of the planetary gear based on the vehicle speed.

Specifically, when the vehicle is in a low-speed traveling state, the gear ratio is varied so that a large steering force can be generated in order to secure parking convenience. When the vehicle is in a high-speed traveling state, the gear ratio is varied so that a small steering force is generated in consideration of driving stability.

In this active steering system, the variable ratio of the planetary gear is generally determined by detecting the difference between the signals detected from the steering angle sensor and the pinion angle sensor. In particular, the steering angle sensor detects power loss, pin contact failure, CAN communication error In case of operating abnormally such as S / W error, a problem may arise in calculation of the variable ratio of the planetary gear. As a result, when the steering angle sensor fails, the steering wheel generates a self steer, and the driver feels a sudden change in vehicle behavior. There is a fatal problem that can affect the life of the driver at high speed.

The following prior art documents relate to Active Front Steering (AFS) technology. More specifically, in the AFS system, when the system is halted in normal or abnormal conditions, there may be a difference in the driver's steering angle before and after the AFS suspension. The present invention is not directed to a self-steering prevention device and method for preventing or alleviating a steering disturbance or a system abnormal operation phenomenon due to motor driving to compensate for the steering angle error.

Korean Patent Publication No. 10-2015-0005238

A control device and a control method of a vehicle front wheel steering system according to an embodiment of the present invention aim at solving the above-mentioned problems.

And to provide a control device and a control method of a vehicle active front wheel steering system capable of ensuring a stable running even when an abnormality of a steering angle sensor or a signal outputted from a steering angle sensor occurs.

The solution to the problem of the present invention is not limited to those mentioned above, and other solutions not mentioned can be clearly understood by those skilled in the art from the following description.

A control device for an active front wheel steering system of a vehicle according to an embodiment of the present invention includes: a planetary gear formed so that a gear ratio can be varied; A motor driven to vary a gear ratio of the planetary gear; And an electronic control unit for controlling the motor based on a signal detected by a vehicle speed sensor, a steering angle sensor and a pinion angle sensor, wherein the electronic control unit determines that the steering angle signal transmitted from the steering angle sensor is abnormal The driving of the motor is stopped, and the steering angle is again estimated to restart the motor.

Wherein the electronic control unit comprises: a first determination unit for determining whether the steering angle signal is abnormal; A second determination unit for determining whether the vehicle is in a straight-ahead state; A steering angle estimating unit for initializing the steering angle based on at least one of the first determining unit and the second determining unit and then re-estimating the steering angle based on the angle detected by the pinion angle sensor; And a control unit for controlling power applied to the motor based on the steering angle estimated by the steering angle estimating unit.

Wherein the control unit stops the driving of the motor by shutting off the power applied to the motor and stops the driving of the motor when the first determining unit determines that the steering angle signal is abnormal, When it is determined that the vehicle is in the straight-ahead state, the steering angle estimating unit preferably initializes the steering angle.

Preferably, the steering angle estimating unit estimates the steering angle based on the angle detected by the pinion angle sensor and the gear ratio of the planetary gear after initializing the steering angle.

Preferably, the electronic control unit further includes a storage unit that stores a gear ratio map of the planetary gear according to the vehicle speed, and the control unit preferably re-drives the motor based on the estimated steering angle and the gear ratio map.

A method of controlling an active front wheel steering system of a vehicle according to an embodiment of the present invention is a method of controlling an active front wheel steering system of a vehicle including a motor and a planetary gear whose gear ratio is variable by driving the motor, A first step of determining whether the steering angle signal transmitted from the sensor is abnormal; A second step of stopping the driving of the motor when it is determined that there is an abnormality in the steering angle signal; A third step of initializing the steering angle when it is determined that the vehicle is in the straight forward state; A fourth step of estimating a steering angle based on an angle detected by the pinion angle sensor; And a fifth step of re-driving the motor based on the estimated steering angle and the vehicle speed detected by the vehicle speed sensor.

The fourth step preferably estimates the steering angle based on the angle detected by the pinion angle sensor and the gear ratio of the planetary gear.

Preferably, in the fifth step, the motor is driven again by using the gear ratio map of the planetary gear according to the vehicle speed.

The control device and the control method of the active front wheel steering system of the vehicle according to the embodiment of the present invention stop the driving of the motor and initialize the steering angle when the steering angle signal is judged to be abnormal, It is possible to expect an effect of ensuring a stable running even when there is an abnormality in the steering angle signal by re-driving the motor again by estimating the steering angle based on the estimated steering angle.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned may be clearly understood by those skilled in the art from the following description.

1 is a diagram showing an active front wheel steering system of a vehicle.
2 is a block diagram illustrating a control apparatus for an active front wheel steering system of a vehicle according to an embodiment of the present invention.
3 schematically shows a gear ratio map.
FIG. 4 is a flowchart illustrating a method of controlling an active front wheel steering system of a vehicle according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.

Hereinafter, an apparatus and method for controlling an active front wheel steering system of a vehicle according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 2 is a block diagram showing a control apparatus for an active front wheel steering system of a vehicle according to an embodiment of the present invention. FIG. 3 schematically shows a gear ratio map Fig.

1, the active steering system of a vehicle includes a steering wheel 101, a steering shaft 103 connected to the steering wheel 101, a steering column 105 surrounding the steering shaft 103, A steering angle sensor 107 provided at the lower end of the column 105, a planetary gear 110 formed below the steering angle sensor 107, a motor 111 for driving the planetary gear 110, and a motor 111 A pinion angle sensor 115 formed on the lower side of the planetary gear 110, a vehicle speed sensor 117 for sensing the speed of the vehicle, An actuator 123 for supplying a steering assist power to the rack bar 119, a steering angle sensor 107 and a motor position sensor 113, and a steering wheel position sensor 113. The rack-and- An electronic control unit (ECU: 12) which receives various signals from the pinion angle sensor 115 and controls the driving of the motor 111 or the actuator 123 5).

In particular, the control apparatus for the active front wheel steering system of the vehicle according to the embodiment of the present invention includes the planetary gear 110, the motor 111 and the electronic control unit 125, as described above. The planetary gear 110 is formed so that the gear ratio can be varied, and the motor 111 functions to vary the gear ratio of the planetary gear 110. The electronic control unit 125 performs a function of controlling the motor 111 based on the signals detected by the vehicle speed sensor 117, the steering angle sensor 107 and the pinion angle sensor 115. Specifically, If the steering angle signal received from the steering angle sensor 107 is determined to be abnormal, the driving of the motor 111 is stopped and the steering angle is estimated again to restart the motor 111.

2, the electronic control unit 125 in the control apparatus of the active front wheel steering system of the vehicle according to the embodiment of the present invention, specifically, A second determination unit 300, a steering angle estimation unit 400, and a control unit 500. The control unit 500 may include a controller 200,

The first determination unit 200 determines whether the steering angle signal transmitted from the steering angle sensor 107 is abnormal. The second determination unit 300 determines whether the vehicle is in the straight state. The steering angle estimating unit 400 also initializes the steering angle based on the determination result of at least one of the first determining unit 200 and the second determining unit 300 and calculates the steering angle based on the angle detected by the pinion angle sensor 115 And performs a function of re-estimating the steering angle. The control unit 500 adjusts the power applied to the motor 111 based on the steering angle estimated by the steering angle estimating unit 400.

The manner in which the active front wheel steering system of the vehicle is controlled based on the configuration of the electronic control unit 125 in the present invention described above in the case of the steering angle signal failure will be specifically described below.

The first determination unit 200 determines that the steering angle signal is abnormal due to an error such as a mechanical defect of the steering angle sensor 107 or a communication error of the steering angle signal after receiving the steering angle signal from the steering angle sensor 107 The control unit 500 firstly stops the driving of the motor 111 by turning off the power applied to the motor 111. [

After the driving of the motor 111 is stopped, the second determination unit 200 determines whether or not the vehicle is currently in a straight forward state. As shown in FIG. When the second determination unit 200 determines that the vehicle is currently in the straight ahead state, the steering angle estimator 400 resets the steering angle to zero and sets the angle detected by the pinion angle sensor 115 and the angle And estimates the steering angle based on the mechanical gear ratio of the engine 110. At this time, the gear ratio of the planetary gear 110 is generally 1.24 or 1.29.

After the estimation of the steering angle is completed, the control unit 500 re-drives the motor 111 based on the estimated steering angle and the gear ratio map. The gear ratio map is a graph showing the gear ratio of the planetary gear 110 according to the vehicle speed And the control unit 125 may further include a storage unit for storing the gear ratio map.

As described above, even when an abnormality occurs in the steering angle signal, the driving of the motor 111 is immediately stopped, the steering angle is estimated based on the pinion angle and the gear ratio of the planetary gear 110, Thereby making it possible to secure a stable running.

Hereinafter, a method of controlling an active front wheel steering system of a vehicle according to an embodiment of the present invention will be described with reference to FIG. 4. In the control apparatus for an active front wheel steering system of a vehicle according to an embodiment of the present invention, The details overlapping with the contents should be omitted. FIG. 4 is a flowchart illustrating a method of controlling an active front wheel steering system of a vehicle according to an embodiment of the present invention.

A method of controlling an active front wheel steering system of a vehicle according to an embodiment of the present invention is a method of controlling an active front wheel steering system of a vehicle including a motor 111 and a planetary gear 110 whose gear ratio is varied by driving of the motor 111 As shown in FIG. 4, the control method includes a first step S100 of determining whether the steering angle signal is abnormal, a second step S200 of stopping the driving of the motor, A third step S300 of estimating the steering angle, a fourth step S400 of estimating the steering angle, and a fifth step S500 of restarting the motor.

The first step S100 is a step of determining whether the steering angle signal transmitted from the steering angle sensor 107 is abnormal or not. If it is determined that the steering angle signal is abnormal in the first step S100, A second step S200 of immediately stopping the process is performed. After the second step S200, it is determined whether the vehicle is in the straight ahead state. If it is determined that the vehicle is in the straight ahead state, a third step S300 of initializing the steering angle to zero is performed.

The fourth step S400 of estimating the steering angle based on the angle detected by the pinion angle sensor 115 is performed after the third step S300. And is calculated based on the pinion angle and the gear ratio of the planetary gear 110. A fifth step S500 of re-driving the motor 111 is performed based on the steering angle estimated at the fourth step S400 and the vehicle speed detected by the vehicle speed sensor 117. More specifically, The motor 111 is driven again by using the gear ratio map of the motor 110. [

The embodiments and the accompanying drawings described in the present specification are merely illustrative of some of the technical ideas included in the present invention. Therefore, it is to be understood that the embodiments disclosed herein are not intended to limit the scope of the present invention but to limit the scope of the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. It should be interpreted.

107: vehicle speed sensor 110: planetary gear
111: Motor 115: Pinion angle sensor
117: vehicle speed sensor 125: electronic control unit
200: first judgment unit 300: second judgment unit
400: steering angle estimating unit 500:

Claims (8)

A planetary gear (110) formed so that a gear ratio is variable;
A motor 111 driven to vary a gear ratio of the planetary gear 110; And
An electronic control unit (125) for controlling the motor (111) based on signals detected by a vehicle speed sensor (117), a steering angle sensor (107) and a pinion angle sensor (115);
/ RTI >
The electronic control unit 125 stops driving the motor 111 when the steering angle sensor 107 receives an error from the steering angle sensor 107 and re-estimates the steering angle to restart the motor 111 The control system of the active front wheel steering system of the vehicle.
The electronic control unit (125) according to claim 1, wherein the electronic control unit (125)
A first determination unit (200) for determining whether the steering angle signal is abnormal;
A second determination unit (300) for determining whether the vehicle is in a straight state;
After initializing the steering angle based on the determination result of at least one of the first determination unit 200 and the second determination unit 300, the steering angle is estimated again based on the angle detected by the pinion angle sensor 115 A steering angle estimating unit 400 for estimating steering angle; And
A controller 500 for adjusting a power applied to the motor 111 based on the steering angle estimated by the steering angle estimator 400;
And a control unit for controlling the steering of the vehicle.
3. The method of claim 2,
If the first determination unit 200 determines that the steering angle signal is abnormal, the control unit 500 stops power supply to the motor 111 to stop driving the motor 111,
If the second determination unit 300 determines that the vehicle is in the straight forward state after the driving of the motor 111 is stopped, the steering angle estimating unit 400 calculates the steering angle of the vehicle, Control device for steering system.
The method of claim 3,
The steering angle estimating unit 400 estimates the steering angle based on the angle detected by the pinion angle sensor 115 and the gear ratio of the planetary gear 110 after initializing the steering angle, Lt; / RTI >
3. The method of claim 2,
The electronic control unit 125 further includes a storage unit for storing a gear ratio map of the planetary gear 110 according to the vehicle speed,
The control unit (500) resumes the motor (111) based on the estimated steering angle and the gear ratio map.
A method of controlling an active front wheel steering system of a vehicle including a motor (111) and a planetary gear (110) having a variable gear ratio by driving the motor (111)
A first step S100 of determining whether the steering angle signal transmitted from the steering angle sensor 107 is abnormal;
A second step (S200) of stopping the driving of the motor (111) when it is determined that there is an abnormality in the steering angle signal;
A third step (S300) of initializing the steering angle when it is determined that the vehicle is in the straight forward state;
A fourth step S400 of estimating the steering angle based on the angle detected by the pinion angle sensor 115; And
A fifth step S500 of re-driving the motor 111 based on the estimated steering angle and the vehicle speed detected by the vehicle speed sensor 117;
And a control system for controlling the steering of the vehicle.
7. The method of claim 6, wherein the fourth step (S400)
And estimating the steering angle based on an angle detected by the pinion angle sensor (115) and a gear ratio of the planetary gear (110).
7. The method of claim 6, wherein the fifth step (S500)
And the motor (111) is driven again by using the gear ratio map of the planetary gear (110) according to the vehicle speed.

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