KR101782714B1 - Active front steering system apparatus for vehicle and controlling method thereof - Google Patents

Abstract

The active front wheel steering apparatus for a vehicle according to an embodiment of the present invention includes: a planetary gear configured to vary a ratio between a rotation angle of an input shaft receiving power of a steering wheel and a rotation angle of an output shaft transmitting power to a rack- A motor driven to vary a gear ratio of the planetary gear; An actuator for driving the rack-and-pinion mechanism portion; And an electronic control unit for determining an abnormal situation upon initial alignment of the steering wheel and the rack-and-pinion mechanism portion based on the torque value of the output shaft.

Description

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

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an Active Front Steering System (AFS) of a vehicle and a control method thereof, and more particularly, And more particularly, to a control device and a control method of an active front wheel steering system capable of solving the above problems.

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.

Such an active front wheel steering system needs a function of adjusting the angle or position of the input shaft and the output shaft to a predetermined angle or position at the time of starting the system. In this process, the input shaft is forcibly rotated by the actuator. At this time, when an object such as a driver's arm or a rod passes through the handle, there is a problem that the handle rotates due to the force generated by the actuator, which may cause driver's injury or damage to the inside of the vehicle.

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

The present invention is directed to an active front wheel steering apparatus for a vehicle and a control method therefor according to an embodiment of the present invention to solve the above-mentioned problems.

The present invention also provides an active front wheel steering apparatus for a vehicle and a control method thereof, which can prevent a safety accident that may occur during the initialization process of the active front wheel steering apparatus of a vehicle and further prevent an overload of a motor for driving an actuator.

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.

The active front wheel steering apparatus for a vehicle according to an embodiment of the present invention includes: a planetary gear configured to vary a ratio between a rotation angle of an input shaft receiving power of a steering wheel and a rotation angle of an output shaft transmitting power to a rack- A motor driven to vary a gear ratio of the planetary gear; An actuator for driving the rack-and-pinion mechanism portion; And an electronic control unit for determining an abnormal situation upon initial alignment of the steering wheel and the rack-and-pinion mechanism portion based on the torque value of the output shaft.

The torque value of the output shaft is preferably calculated on the basis of the input shaft angle sensor and the output shaft angle sensor or is measured by the output shaft torque sensor.

The electronic control unit includes a comparator for comparing a torque value of the output shaft at the time of initial alignment of the steering wheel and the rack-and-pinion mechanism with a predetermined value; A determination unit for determining whether or not an abnormal situation is present based on the comparison result of the comparison unit; And an actuator driving unit for controlling the actuator based on the determination result of the determination unit.

When the torque value of the output shaft that is equal to or greater than the predetermined value lasts for a first predetermined time, the determination unit determines that an abnormal situation occurs when the steering wheel and the rack-pinion mechanism unit are initially aligned.

The electronic control unit may further include a warning unit for sending an error message to the user when the abnormal situation occurs.

When it is determined that the abnormality has occurred, the actuator driving unit preferably interrupts power supply to the actuator for a second predetermined time.

The method of controlling an active front wheel steering apparatus of a vehicle according to an embodiment of the present invention is configured to change a ratio between a rotational angle of an input shaft to which power of a steering wheel is transmitted and a rotational angle of an output shaft that transmits power to a rack- A control method for a vehicle active front wheel steering apparatus including a planetary gear, a motor driven to vary a gear ratio of the planetary gear, and an actuator for driving the rack-and-pinion mechanism, Receiving a signal; Determining whether the current operating mode is the initial alignment mode of the steering wheel and the rack-and-pinion mechanism portion; Determining whether an abnormal situation occurs in the initial alignment based on the detection signal of the sensor when the current operation mode is determined as the initial alignment mode; And a step of warning the user or controlling the actuator based on the determination result of the occurrence of the abnormal situation in the initial alignment.

The sensor is preferably at least one of an input shaft angle sensor, an output shaft angle sensor and an output shaft torque sensor.

The step of determining whether or not an abnormal situation occurs during the initial alignment includes: calculating a torque value of the output shaft based on a detection signal of the sensor; Determining whether a torque value of the output shaft is equal to or greater than a predetermined value; Determining whether a torque value of the output shaft that is equal to or greater than the preset value continues for a first predetermined time; And determining whether an abnormal situation occurs during initial alignment based on the magnitude and continuity of the torque value of the output shaft.

The step of warning the user or controlling the actuator includes sending the abnormal situation occurrence message to the user; Blocking the power applied to the actuator; Determining whether a power cut-off time of the actuator exceeds a preset second time; And applying power to the actuator based on the power cutoff time of the actuator.

In the active front wheel steering apparatus for a vehicle and the control method therefor according to an embodiment of the present invention, it is determined whether or not the steering wheel is loaded on the basis of the torque value of the output shaft during the initial alignment process performed at the start of the system, It is possible to expect the effect of preventing the safety accident by allowing the driver to recognize the dangerous situation.

In addition, by stopping the operation of the actuator for driving the rack-and-pinion mechanism portion for a preset time based on whether or not the steering wheel is loaded, it is possible to prevent an overload of the motor when the input shaft and the output shaft are fixed.

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 view showing an active front wheel steering apparatus for a vehicle.
2 is a block diagram showing in detail an electronic control unit of an active front wheel steering apparatus of a vehicle according to an embodiment of the present invention.
3 is a flowchart illustrating a method of controlling an active front wheel steering apparatus of a vehicle according to an embodiment of the present invention in a time-series manner.
Figures 4 and 5 are flow charts illustrating some of the steps of Figure 3 in more detail.

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, a control apparatus and a control method of 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 and 2. FIG. Fig. 1 is a diagram showing an active front wheel steering system of a vehicle, and Fig. 2 is a block diagram specifically showing an electronic control unit of an active front wheel steering apparatus of a vehicle according to an embodiment of the present invention.

1, an active steering system of a vehicle includes a steering wheel 101, an input shaft 103 connected to the steering wheel 101, a steering shaft 103 surrounding the input shaft 103, A steering angle sensor 107 provided at the lower end of the steering column 105, a planetary gear 110 formed below the steering angle sensor 107, a motor 111 for driving the planetary gear 110, A motor speed sensor 117 for sensing the speed of the vehicle and a rotation sensor for detecting a rotation speed of the output shaft 124 under the planetary gear 110, A pinion torque sensor and a pinion angle sensor 115 for respectively detecting a rotation torque and a rotation angle of the output shaft 124, an actuator for supplying a steering assist power to the rack bar 119, (123). Although not explicitly shown in FIG. 1, a solenoid valve is provided to prevent a malfunction of the system in the event that the active front wheel steering system is unable to operate normally. Specifically, when it is determined that the system malfunction, the solenoid valve And functions to limit the function of the motor 111 by fixing the motor 111 by turning it on. An electronic control unit (ECU) 114 receives various signals from the input shaft rotation angle sensor 107 and the motor position sensor 113 and controls driving of the motor 111, the solenoid valve, the motor 111 or the actuator 123, 125).

Hereinafter, an active front wheel steering apparatus according to an embodiment of the present invention will be described in detail with reference to the entire contents of the active front wheel steering apparatus described above and FIGS. 1 and 2. FIG. An active front wheel steering apparatus for a vehicle according to an embodiment of the present invention mainly includes a planetary gear 110, a motor 111, an actuator 123, and an electronic control unit 125.

The planetary gear 110 is connected to the input shaft 103 through which the power of the steering wheel 101 is transmitted at one side and the output shaft 124 and the output shaft 124 at which power is transmitted to the rack- It is connected. In particular, the planetary gear 110 is formed so that the ratio between the rotation angle of the input shaft 103 and the rotation angle of the output shaft 124 can be varied.

The actuator 111 is configured to be driven to vary the variable ratio of the planetary gear 110 and the actuator 123 is configured to supply the steering assist power to the rack bar 119 of the rack- , And a motor other than the motor 111 for changing the gear ratio of the planetary gear 110.

The electronic control unit 125 performs a function of determining an abnormal situation upon initial alignment of the steering wheel 101 and the rack-pinion mechanism section 121 based on the torque value of the output shaft 124. [ As described above, the active front wheel steering apparatus of the vehicle must essentially perform a function of aligning the input shaft 103 and the output shaft 124 immediately after the system is turned on. In the course of performing the initial alignment function, Or the output shaft 124 rotates arbitrarily or forcibly, and when the tire is fixed by a curb or the like while performing such a function, or when the handle is fixed due to a malfunction of the mechanism or the driver's arm being stuck on the handle, A current may continuously flow through the actuator 123 to overheat the actuator 123 or the electronic control unit 125. At the same time, a safety accident may occur.

In order to prevent the above-described problem, the electronic control unit 125 determines an abnormal situation at the time of initial alignment based on the torque value of the output shaft 124, and when it is determined that the abnormality is present, the actuator 123 or the warning device And controls to take subsequent actions. In this case, the torque value of the output shaft 124 can be obtained based on at least one of the input shaft angle sensor, the output shaft angle sensor, and the output shaft torque sensor. Hereinafter, referring to FIG. 2, The electronic control unit 125 of the active front wheel steering apparatus of the present invention will be described in more detail.

2, an electronic control unit 125 of an active front wheel steering apparatus of a vehicle according to an embodiment of the present invention includes a comparison unit 200, a determination unit 300, and an actuator driving unit 400 .

The comparator 200 performs a function of comparing the torque value of the output shaft 124 at the time of initial alignment of the steering wheel 101 and the rack-and-pinion mechanism portion 121 with a predetermined value (a). Based on the comparison result in the comparison unit 200, the determination unit 300 determines whether the active front wheel steering apparatus is in an abnormal state at the time of initial alignment. Specifically, when it is determined in the comparing unit 200 that the torque value of the output shaft 124 is equal to or less than a preset value (a), the determining unit 300 determines that the process of initial alignment of the active front wheel steering apparatus is normal . On the contrary, when it is determined that the torque value of the output shaft 124 exceeds the predetermined value (a) in the comparison unit 200, the determination unit 300 determines that the input shaft 103 Or an unnecessary load is applied to the output shaft 124. Thus, it is determined that an abnormal situation occurs during the initial alignment of the active front wheel steering apparatus. Here, the predetermined value (a) may be, for example, 4N * m.

On the other hand, when the torque value of the output shaft 124 temporarily exceeds the preset value (a), the determination unit 300 determines the torque value of the output shaft 124 exceeding the preset value (a) It is determined that an abnormal situation has occurred at the time of initial alignment of the active front wheel steering apparatus. For example, when the torque value exceeding the preset value (a) continues for 1 second or longer, the determination unit 300 determines that an abnormal situation occurs during the initial alignment of the active front wheel steering apparatus.

In addition, the electronic control unit 125 of the active front wheel steering apparatus of the vehicle according to the embodiment of the present invention may further include the warning unit 500. [ The warning unit 500 functions to send an error message to the user when the determination unit 300 of the electronic control unit 125 determines that an abnormal situation occurs during initial alignment of the active front wheel steering apparatus. For example, it is possible to warn the driver of an error in initial alignment through a speaker or the like mounted on a vehicle, and it is also possible to output a warning message through a display mounted on the vehicle.

As described above, when the determination unit 300 determines that an abnormal situation occurs during initial alignment of the active front wheel steering apparatus, the actuator driving unit 400 controls the actuator 123 based on the determination result. Specifically, the actuator driver 400 interrupts the forced rotation of the output shaft 124 by interrupting the power supply to the actuator 123, and in particular, the actuator driver 400 drives the actuator 123 only for a second predetermined time t2. It is preferable that the power supply is cut off. This is for securing a time for eliminating the cause of the abnormal situation after the driver recognizes the abnormal situation in the initial alignment by the warning unit 500 described above. For example, when the steering wheel is fixed by a tool such as a stick, the determination unit 300 determines that an abnormal situation occurs during initial alignment, and causes the warning unit 500 to recognize the abnormal situation to the driver The power supply to the actuator 123 is cut off. In this case, the driver recognizing the abnormal situation removes the stick inserted in the steering wheel within a second predetermined time t2. After the predetermined second time t2, the actuator driving unit 400 drives the actuator 123 So that a smooth initial alignment process is performed.

Hereinafter, a method of controlling an active front wheel steering apparatus for a vehicle according to an embodiment of the present invention will be described with reference to FIGS. 3 to 5. In the active front wheel steering apparatus for a vehicle according to an embodiment of the present invention, The detailed description thereof is omitted. FIG. 3 is a flow chart illustrating a method of controlling an active front wheel steering apparatus of a vehicle according to an embodiment of the present invention in a time-series manner, and FIGS. 4 and 5 are diagrams illustrating partial steps of FIG. Flow chart.

The control method of the active front wheel steering apparatus of the vehicle according to the embodiment of the present invention is a method of controlling the steering angle of the input shaft 103 receiving the power of the steering wheel 101 and the rotation angle of the output shaft transmitting the power to the rack- A motor 111 driven to vary the gear ratio of the planetary gear 110 and an actuator 123 for driving the rack-and-pinion mechanism portion 121. The planetary gear 110 is a planetary gear, To a control method of an active front wheel steering apparatus for a vehicle. More specifically, as shown in FIG. 3, a step S100 of receiving a detection signal of the sensor, a step S200 of determining whether the sensor is in the initial alignment mode, a step S300 of determining whether an abnormal situation occurs, (S400).

Specifically, the step (S100) of receiving the detection signal of the sensor is preferably a detection signal of a sensor mounted on the vehicle, and the sensor mounted on the vehicle is at least one of an input shaft angle sensor, an output shaft angle sensor and an output shaft torque sensor. In operation S200, it is determined whether the operation mode of the active front wheel steering apparatus is the initial alignment mode. If it is determined that the operation mode of the active front wheel steering apparatus is the initial alignment mode, step S300 is performed .

In step S300 of determining whether or not an abnormal situation occurs in the initial alignment, it is determined whether or not an abnormal situation has occurred based on the detection signal of the sensor, and it may be subdivided into four stages as shown in FIG. More specifically, a step S320 of calculating a torque value of the output shaft 124 based on the detection signal of the sensor (S310), and determining whether the calculated torque value of the output shaft 124 exceeds a predetermined value (a) Is performed. If the torque value of the output shaft 124 exceeding the predetermined value a is smaller than the predetermined value a, for example, 4N * m, (S330) is performed to determine whether it is continued for one hour (t1), for example, for one second, and when the initial alignment of the active front wheel steering apparatus is performed based on the magnitude and continuity of the torque value of the output shaft A step S340 of determining whether or not a situation has occurred is performed. That is, when the torque value of the output shaft 124 exceeds the predetermined value (a) and the torque value exceeding the predetermined value (a) continues for the preset time t1, It is determined that an abnormal situation has occurred during the initial alignment of the active front wheel steering apparatus, and the step of controlling the warning and the actuator (S400) is performed, which will be described in detail with reference to FIG.

In step S400, the warning is given to the user or the actuator is controlled in step S400. In step S410, a warning message is sent as shown in FIG. 5, a step S420 of turning off the actuator power supply, Step S430 and re-applying the actuator power (S440).

First, if the electronic control unit 125 determines that there is an abnormality in the initial alignment of the active front wheel steering apparatus, step S410 of sending an abnormal situation occurrence message to the user to recognize the abnormal situation is performed. Thereafter, step S420 of cutting off the power applied to the actuator 123 to prevent the overload or overheating of the actuator 123 and the electronic control unit 125 is performed. However, in the case of the power cut off time of the actuator 123, after the user recognizes the initial alignment abnormality due to the warning and sufficiently secures the time for performing the cause removal which causes the abnormal condition, (S430) is performed to determine whether the power supply cutoff time of the actuator 123 has exceeded the preset second time t2. If the power-off time exceeds the predetermined second time t2, the controller 123 applies the power to the actuator 123 again (S440) as described above.

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.

101: steering wheel 103: input shaft
107: steering angle sensor 110: planetary gear
111: motor 113: motor position sensor
115: Pinion angle sensor 124: Output shaft
125: Electronic control unit 200:
300: determination unit 400: actuator driving unit
500: Warning section

Claims (10)

A planetary gear formed so as to be able to vary a ratio between a rotation angle of an input shaft receiving the power of the steering wheel and a rotation angle of an output shaft transmitting power to the rack-and-pinion mechanism;
A motor driven to vary a gear ratio of the planetary gear;
An actuator for driving the rack-and-pinion mechanism portion;
An electronic control unit for determining an abnormal situation in initial alignment of the steering wheel and the rack-and-pinion mechanism based on a torque value of the output shaft, and controlling the power supply of the actuator to be interrupted for a predetermined time when an abnormal situation occurs;
And an active front wheel steering device.
The method according to claim 1,
Wherein the torque value of the output shaft is calculated based on the input shaft angle sensor and the output shaft angle sensor or is measured by an output shaft torque sensor.
The electronic control unit according to claim 1,
A comparison unit comparing a torque value of the output shaft at the time of initial alignment of the steering wheel and the rack-and-pinion mechanism unit with a predetermined value (a);
A determination unit for determining whether or not an abnormal situation is present based on the comparison result of the comparison unit; And
An actuator driving unit for controlling the actuator based on a determination result of the determination unit;
And an active front wheel steering device.
The method of claim 3,
Wherein when the torque value of the output shaft exceeding the preset value continues for a first predetermined time, the determining unit determines that the steering wheel and the rack- Steering device.
The method of claim 3,
Wherein the electronic control unit further includes a warning unit for sending an error message to the user when the abnormal situation occurs.
The method of claim 3,
Wherein the actuator driving unit interrupts power supply to the actuator for a second predetermined time when the determination unit determines that the abnormal situation has occurred.
A planetary gear configured to change a ratio between a rotation angle of an input shaft receiving the power of the steering wheel and a rotation angle of an output shaft transmitting power to the rack-and-pinion mechanism, a motor driven to vary a gear ratio of the planetary gear, A control method of an active front wheel steering apparatus for a vehicle including an actuator for driving a rack-and-pinion mechanism portion,
Receiving a detection signal of a sensor mounted on a vehicle;
Determining whether the current operating mode is the initial alignment mode of the steering wheel and the rack-and-pinion mechanism portion;
Determining whether an abnormal situation occurs in the initial alignment based on the detection signal of the sensor when the current operation mode is determined as the initial alignment mode; And
Controlling the power supply of the actuator to be shut off for a predetermined time based on a result of determining whether an abnormal situation occurs during initial alignment;
And a control unit for controlling the steering of the vehicle.
8. The method of claim 7,
Wherein the sensor is an input shaft angle sensor, an output shaft angle sensor, or an output shaft torque sensor.
The method as claimed in claim 7, wherein the step of determining whether an abnormal situation occurs in the initial alignment includes:
Calculating a torque value of the output shaft based on a detection signal of the sensor;
Determining whether a torque value of the output shaft exceeds a preset value;
Determining whether a torque value of the output shaft exceeding the predetermined value continues for a first predetermined time; And
Determining whether an abnormal situation occurs during initial alignment based on the magnitude and continuity of the torque value of the output shaft;
And a control unit for controlling the steering of the vehicle.
8. The method of claim 7,
Sending the abnormal situation occurrence message to a user;
Blocking the power applied to the actuator;
Determining whether a power cut-off time of the actuator exceeds a preset second time; And
Applying power to the actuator based on a power cutoff time of the actuator;
And a control unit for controlling the steering of the vehicle.

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