KR20090006275A - Vehicle stability control device and method - Google Patents

Abstract

An apparatus for controlling stability for the vehicles and stability control method is provided to perform yaw moment corresponding to the determined result is authorized in an actuator regardless of the change of the vehicle condition. An apparatus for controlling stability for the vehicles comprises the vehicle speed sensor(11) sensing the velocity of car; the yaw rate sensor(13) sensing the yaw rate of the vehicles; the actuator(45) controlling the rigidity of the stabilizer bar which the vehicles; the electronic control unit(20) controlling actuator according to the yaw moment corresponding to the determined result which determines whether oversteer or not.

Description

Vehicle attitude control device and its attitude control method {vehicle stability control device and method}

1 is a block diagram illustrating a vehicle attitude control device according to an embodiment of the present invention.

2 is a flowchart illustrating an attitude control method of a vehicle attitude control device according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

11: vehicle speed sensor 12: steering angle sensor

13: yaw rate sensor 20: electronic control unit

21: receiver 22: calculator

23: determination unit 24: rigidity control unit

30: Memory 40: Stabilizer Bar

45: actuator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle attitude control device and a control method thereof, and in particular, by controlling the driving of the actuator to adjust the stiffness of the stabilizer bar according to the yaw moment determined in consideration of the driving state of the vehicle as a whole. And it relates to a vehicle attitude control device and a control method for ensuring a ride comfort.

In general, in the suspension system of a vehicle, a stabilizer bar is mounted to the vehicle body in a transverse direction so that the vehicle itself has a rolling of the vehicle body caused by a change in the relative attitude of the left and right suspensions while driving. By mitigating the roll stiffness that is present, it is possible to further stabilize the behavior of the vehicle body.

This stabilizer bar is applied only when there is a difference in the movement of the wheels, so that the movement of the left and right wheels is equal to the movement of the outer wheels or the inner wheels when the cornering occurs. The inclination is minimized, the roll phenomenon of the vehicle body is suppressed, and the ride comfort and the vehicle body are stabilized.

In controlling the stiffness adjustment of the stabilizer bar, since the vehicle posture control is performed using the conventional steering angle and the vehicle speed, the stiffener bar is released during driving on a flat road to secure a riding comfort and stabilizer during rapid steering. The rigidity of the bar was applied to ensure steering stability.

However, since the vehicle attitude control is performed without considering the behavior of the vehicle under uneven road conditions or unpredictable road conditions, there is a limit to the performance improvement of the vehicle attitude control.

An object of the present invention is to control the driving of the actuator to adjust the rigidity of the stabilizer bar according to the roll moment determined in consideration of the driving state of the vehicle as a whole, as well as to ensure the stability of the vehicle and the riding comfort, It is to improve the performance of the posture control.

Vehicle attitude control apparatus according to an embodiment of the present invention for achieving the above object is a vehicle speed sensor for sensing the speed of the vehicle; A steering angle sensor for detecting a steering angle of the vehicle; A yaw rate sensor for detecting a yaw rate of the vehicle; An actuator for adjusting the rigidity of the stabilizer bar mounted to the vehicle; And a yaw rate value is calculated using the detected speed and steering angle of the vehicle, and the difference between the calculated yaw rate value and the yaw rate value sensed by the yaw rate sensor is compared with a preset threshold value. And an electronic control unit which determines whether it is a steer or an understeer and controls the actuator according to the yaw moment corresponding to the determined result.

Preferably, the electronic control unit includes a receiver for receiving the speed, steering angle and yaw rate of the vehicle detected from the vehicle speed sensor, the steering angle sensor and the yaw rate sensor; A calculator configured to calculate a yaw rate value of the vehicle using the received vehicle speed and steering angle; A determination unit for comparing the difference between the calculated yaw rate value and the yaw rate value received by the reception unit with a preset threshold value and determining whether it is an oversteer or an underseer; And a stiffness controller configured to adjust the stiffness of the stabilizer bar by configuring the actuator to be compensated by reflecting the yaw moment corresponding to the determined result to each displacement of the stabilizer bar.

More preferably, the actuator is characterized in that it comprises any one of an electric motor, a hydraulic modulator.

In addition, the attitude control method of the vehicle attitude control apparatus according to an embodiment of the present invention comprises the steps of receiving the speed, steering angle and yaw rate of the vehicle detected from the vehicle speed sensor, steering angle sensor and yaw rate sensor; Calculating a yaw rate value of the vehicle using the received vehicle speed and steering angle; Determining whether the vehicle is oversteer or understeer by comparing a difference between the calculated yaw rate value and the yaw rate value received by the yaw rate sensor with a preset threshold value; And adjusting the rigidity of the stabilizer bar by driving the actuator according to the yaw moment corresponding to the determination result.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a block diagram illustrating a vehicle attitude control apparatus according to an embodiment of the present invention.

Referring to FIG. 1, a vehicle attitude control apparatus according to an embodiment of the present invention includes a vehicle speed sensor 11, a steering angle sensor 12, and a yaw rate sensor. 13 and the yaw rate value and preset threshold value calculated using the actuator 45 for adjusting the rigidity of the stabilizer bar 40 installed on the front wheel and the rear wheel, and the speed, steering angle, and yaw rate of the vehicle. An electronic control unit (hereinafter referred to as 'ECU') that determines whether it is over steer or under steer in comparison and controls driving of the actuator 45 according to the yaw moment corresponding to the determined result. It comprises 20.

In addition, the vehicle attitude control apparatus according to the present invention further comprises a lateral acceleration sensor (not shown) for detecting the lateral acceleration of the vehicle, the lateral acceleration signal detected from the lateral acceleration sensor ECU (Electronic Control Unit) ( 20) to provide. At this time, the lateral acceleration signal is used as an indirect factor for increasing the reliability of the attitude control of the vehicle.

The vehicle speed sensor 11 is called a wheel speed sensor that can sense the speed of the vehicle, and detects the speed of the vehicle to provide the detected speed signal to the ECU 20.

The steering angle sensor 12 detects a steering angle of the vehicle and provides the detected steering angle signal to the ECU 20. The steering angle sensor 12 is installed on a steering shaft (not shown) of the steering wheel, and detects the steering angle according to the driver's steering wheel manipulation.

The yaw rate sensor 13 is installed inside the vehicle and detects the degree of turning according to the turning of the vehicle, and provides the detected degree of turning to the ECU 20.

The stabilizer bar 40 is installed along the vehicle body in the transverse direction. The stabilizer bar 40 functions as an auxiliary spring for supporting the left and right wheels generated when the vehicle body is rolled, and when the left and right wheels move in phase, they do not receive force, and when they move in reverse phase, they are left and right by torsional elastic force. Constrain the movement of the wheels to reduce the roll behavior of the body.

The ECU 20 detects the driving state of the vehicle from the vehicle speed sensor 11, the steering angle sensor 12, and the yaw rate sensor 13 to adjust the stiffness of the stabilizer bar 40 installed at the front and rear wheels, respectively. It functions to control the operation of the actuator 45.

Here, the ECU 20 operates to exert a force on the stabilizer bar 40 connected to the actuator 45 to optimally control the driving state of the vehicle, that is, the attitude and stability of the vehicle.

In addition, the ECU 20 controls the actuator 45 by controlling and outputting a current value in various ways such as PWM (Pulse Width Modulation).

The actuator 45 is installed in each of the stabilizer bar 40 installed on the front and rear wheels, respectively.

The actuator 45 is a device for adjusting the rigidity of the stabilizer bar 40 and may be configured as an electric motor or a hydraulic modulator using a motor and a gear.

When the actuator 45 is configured as a hydraulic modulator, the ECU 20 controls the flow rate flowing into the front and rear wheel actuators by the operation of the actuator 45.

Accordingly, the ECU 20 actively controls the state of movement of the vehicle by controlling the hydraulic flow rate of the hydraulic actuators attached to the front and rear wheels of the vehicle, thereby simultaneously realizing the riding comfort and adjustment stability that cannot be obtained from the stabilizer bar 40. It becomes possible.

In detail, the ECU 20 applies the yaw rate value by applying the speed, steering angle, and yaw rate received from the vehicle speed sensor 11, the steering angle sensor 12, and the yaw rate sensor 13 according to a preset calculation method. It calculates and compares the calculated yaw rate value with a preset threshold to determine whether it is oversteer or understeer and controls the driving of the actuator 45 according to the yawment proportional to the determination.

The ECU 20 includes a receiver 21, a calculator 22, a determiner 23, and a stiffness adjuster 24.

The receiver 21 receives the speed, the steering angle, and the yaw rate of the vehicle detected from the vehicle speed sensor 11, the steering angle sensor 12, and the yaw rate sensor 13.

)을 계산한다.The calculating unit 22 calculates the yaw rate value (

Calculate

'는 차량의 속도이고, '

'은 전륜센터와 후륜센터 사이의 직선거리이고, '

'는 전륜 조향각이며, '

'는 언더 스티어 특성 게인으로, 미리 정의되어 있는 값이다.From here, '

'Is the speed of the vehicle,'

Is the straight line distance between the front and rear wheel centers,

Is the front wheel steering angle,

'Is an understeer characteristic gain, which is a predefined value.

In addition, the calculator 22 calculates a difference between the yaw rate value calculated by the calculator 22 and the yaw rate value sensed by the yaw rate sensor 13.

The determination unit 23 compares the difference between the yaw rate value calculated by the calculation unit 22 and the yaw rate value sensed by the yaw rate sensor 13 with a preset threshold to determine whether it is oversteer or understeer. Determine. In this case, the preset threshold value is a state previously stored in the memory 30.

When the rigidity adjusting unit 24 determines the oversteer or understeer by the determining unit 23, the rigidity adjusting unit 24 generates the yaw moment corresponding to the determination result and controls the driving of the actuator 45 according to the generated yaw moment. The stiffness of the stabilizer bar 40 is adjusted by driving the actuator 45 so that the yaw moment is reflected in each displacement of the stabilizer bar 40.

In more detail, when the rigidity adjusting unit 24 determines the oversteer by the determining unit 23, the rigidity adjusting unit 24 increases the rigidity of the stabilizer bar installed on the front wheel side to a preset reference value and increases the rigidity of the stabilizer bar installed on the rear wheel side. The stiffness of the stabilizer bar 40 is adjusted by controlling the driving of the actuator 45 to reduce the predetermined reference value. Here, the preset reference value is also stored in the memory 30 in advance.

In addition, when the rigidity adjusting unit 24 determines the understeer by the determining unit 23, the rigidity adjusting unit 24 increases the rigidity of the stabilizer bar installed on the rear wheel side to a preset reference value and presets the rigidity of the stabilizer bar installed on the front wheel side. The stiffness of the stabilizer bar 40 is adjusted by controlling the drive of the actuator 45 to reduce it to the reference value.

The attitude control method of the vehicle attitude control device having such a configuration will be described below with reference to FIG. 2.

The receiver 21 of the ECU 20 receives the speed, the steering angle, and the yaw rate of the vehicle detected from the vehicle speed sensor 11, the steering angle sensor 12, and the yaw rate sensor 13 (S101).

Next, the calculation unit 22 of the ECU 20 calculates the yaw rate value using the above-described Equation 1 for the speed and the steering angle of the received vehicle (S103).

Next, the determining unit 23 of the ECU 20 compares the difference between the calculated yaw rate value and the yaw rate value sensed by the yaw rate sensor 13 with a preset threshold to determine whether the vehicle is oversteer. It is determined (S105). At this time, the preset threshold is stored in the memory 30.

As a result of the determination in step S105, when the vehicle is determined to be the oversteer, the stiffness control unit 24 increases the rigidity of the stabilizer bar installed at the front wheel side according to the yaw moment corresponding to the result of the oversteer. The drive of the actuator 45 is controlled to reduce the rigidity of the stabilizer bar installed on the rear wheel side, and the rigidity of the stabilizer bar 40 installed on the front and rear wheels is adjusted (S106).

As a result of the determination in step S105, when the vehicle is not determined to be oversteer, the determination unit 22 compares the calculated yaw rate value with a preset threshold value and determines whether it is understeer (S107).

As a result of the determination in step S107, when the vehicle is not determined to be an understeer, the stiffness adjusting unit 24 stops driving the actuator 45 for adjusting the stiffness of the stabilizer bar 40 to stabilize the stabilizers installed on the front and rear wheels. Adjust so as not to add rigidity to the bar 40 (S108).

As a result of the determination in step S107, when the vehicle is determined to be an understeer, the stiffness control unit 24 reduces the rigidity of the stabilizer bar installed at the front wheel side according to the yaw moment corresponding to the result of the determination as the understeer. Controlling the drive of the 45, and controls the drive of the actuator 45 to increase the rigidity of the stabilizer bar installed on the rear wheel side to adjust the rigidity of the stabilizer bar 40 installed on the front and rear wheels (S109).

In this way, since the control target of the vehicle is determined, it is possible to perform a consistent attitude control regardless of the variation of the vehicle conditions.

The present invention is not limited to the embodiments described above, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention as defined in the appended claims.

According to the present invention as described above by driving the actuator to adjust the stiffness of the stabilizer bar in accordance with the yaw moment determined in consideration of the driving state of the vehicle, there is an effect that can secure the adjustment stability and ride comfort of the vehicle.

In addition, according to the present invention as described above by determining whether the vehicle is an oversteer or understeer, and by applying a yaw moment corresponding to the determined result to the actuator, it is possible to perform a consistent attitude control regardless of the variation of the vehicle conditions In addition, there is an effect that can prevent the vehicle overturning.

Claims (4)

A vehicle speed sensor detecting a speed of the vehicle; A steering angle sensor for detecting a steering angle of the vehicle; A yaw rate sensor for detecting a yaw rate of the vehicle; An actuator for adjusting the rigidity of the stabilizer bar mounted to the vehicle; And The yaw rate value is calculated using the detected speed and steering angle of the vehicle, and the difference between the calculated yaw rate value and the yaw rate value sensed by the yaw rate sensor is compared with a preset threshold value. And an electronic control unit for determining whether the vehicle is under steering or under steering and controlling the actuator according to the yaw moment corresponding to the determined result. The method of claim 1, wherein the electronic control unit A receiver configured to receive the vehicle speed, steering angle, and yaw rate detected by the vehicle speed sensor, the steering angle sensor, and the yaw rate sensor; A calculator configured to calculate a yaw rate value of the vehicle using the received vehicle speed and steering angle; A determination unit for comparing the difference between the calculated yaw rate value and the yaw rate value received by the reception unit with a preset threshold value and determining whether it is an oversteer or an underseer; And And a stiffness adjuster configured to adjust the stiffness of the stabilizer bar by configuring the actuator to be compensated by reflecting the yaw moment corresponding to the determined result to each displacement of the stabilizer bar. The method of claim 1, wherein the actuator Attitude control device for a vehicle comprising any one of an electric motor and a hydraulic modulator. In a posture control method of a vehicle attitude control device including a vehicle speed sensor, a steering angle sensor, a yaw rate sensor and an actuator for adjusting the rigidity of the stabilizer bar, Receiving a speed, a steering angle, and a yaw rate of the vehicle detected from the vehicle speed sensor, the steering angle sensor, and the yaw rate sensor; Calculating a yaw rate value of the vehicle using the received vehicle speed and steering angle; Determining whether the vehicle is oversteer or understeer by comparing a difference between the calculated yaw rate value and the yaw rate value received by the yaw rate sensor with a preset threshold value; And And controlling the stiffness of the stabilizer bar by driving the actuator according to the yaw moment corresponding to the determination result.

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