KR20110062440A - Support system for lateral driving and control method thereof - Google Patents

Abstract

PURPOSE: A lateral driving support system and control method thereof are provided to make electronic platform of the lateral driving support system by controlling lateral safety steering using modulated software. CONSTITUTION: A control method of a lateral driving support system includes the following steps: extracting information which includes a departure angle and a departure distance of a vehicle from an image gained through an image sensor; estimating information related to steering; calculating steering torque with integrated status space equation; measuring departure estimated distance of the vehicle from road information; and controlling a steering actuator with the calculated steering torque.

Description

Support system for lateral driving and control method

The present invention relates to a lateral driving support system for a vehicle and a control method thereof. More specifically, the present invention relates to a lateral driving assistance system for a vehicle capable of performing lateral safety steering control against lane departure warning, lane keeping support, and lateral disturbance caused by lateral wind.

In the related art, the lane departure warning device, the lane keeping support device, and the lateral safety steering control device are individually configured with respect to the transverse driving safety. The lane departure warning device recognizes the geometric information of the driving lane from the image sensor and is a device that alerts the driver by using a sound source device or an electric safety belt when the vehicle is expected to leave the lane. In addition, the lane maintenance support device is a device that provides steering torque to the steering actuator in real time to support the steering force required for the driver's steering and steering operation so that the vehicle can drive following the driving lane. Lastly, the lateral safety steering control device prevents the driver's steering ability or lateral stability from being affected by lateral disturbances such as breezes. It is a device that functions to alert the driver or to actively control the steering so as to minimize the effect of the observation and observe it. Therefore, in the conventional automobile, the driver is warned when the lane is departed, the vehicle is supported to follow the lane, or when the disturbance occurs due to the cross wind, the control is performed separately.

On the other hand, the performance and price of automobiles are shifting from hardware to software in recent years. Accordingly, hardware platforms such as power trains, chassis, engines, etc., along with electronic platforms such as ECU deployment and processing performance, network configuration and software deployment, etc. The research is being actively conducted.

In this development process, there is a need for a lateral driving support system and a control method capable of integrally controlling the functions of the lane departure warning device, the lane keeping support device, and the lateral safety steering control device.

The present invention has been proposed by such a request, and an object of the present invention is to provide a transverse driving assistance system and a control method thereof capable of integrally controlling lane departure warning, lane keeping support, and lateral safety steering control.

In order to achieve the above object, the lateral driving support system according to the present invention comprises: a road information extractor for extracting road information including a departure angle and a departure distance of the vehicle from an image obtained through an image sensor installed in the vehicle; An observer that receives information related to vehicle attitude and steering from sensors installed in the vehicle and estimates steering related information including steering angle velocity, transverse velocity and lateral disturbance caused by draft by using the same; Control unit for calculating steering torque by using the road information and steering related information from the road information extractor and the observer in an integrated state space equation with steering angle speed, steering angle, lateral speed, yaw rate, departure angle and departure distance as state variables ; And a steering actuator controlled by an output signal of the steering torque transmitted from the control unit.

In addition, in the lateral driving support system according to the present invention, the control unit calculates the departure distance of the vehicle from the road information before outputting the output signal of the steering torque, and in contrast with the speed of the vehicle, the vehicle leaves the lane It is characterized by generating a control signal for classifying a plurality of risks according to the degree of control and controlling different kinds of alarm devices according to the plurality of risks.

In addition, in the transverse driving support system according to the present invention, the alarm device is an HMI device for real-time notification of the operating state of the transverse driving support system, an acoustic warning speaker and a vibrating device for tactilely giving a vibration to the driver It is characterized by that.

In addition, in the lateral driving support system according to the present invention, the sensors installed in the vehicle, the lateral acceleration sensor for measuring the lateral acceleration, the steering angle sensor for measuring the steering angle of the steering wheel, the inertial sensor for measuring the yaw angle and the speed of the vehicle It characterized in that it comprises a vehicle speed sensor.

In addition, the lateral driving assistance system control method according to the present invention comprises the steps of: extracting the road information including the departure angle and departure distance of the vehicle from the image obtained through the image sensor installed in the vehicle; Estimating steering related information including steering angular velocity, lateral velocity and lateral disturbance caused by draught by using values related to vehicle attitude and steering from sensors installed in the vehicle; Calculating steering torque by using the road information and steering related information in an integrated state space equation using steering angle speed, steering angle, lateral speed, yaw rate, deviation angle, and deviation distance as state variables; Calculating a distance estimating distance of the vehicle from the road information and alerting the driver according to the degree to which the vehicle leaves the lane in comparison with the speed of the vehicle; And controlling the steering actuator with the calculated steering torque.

The present invention utilizes an integrated state space equation with the state variables of steering angle speed, steering angle, yaw rate, departure angle and departure distance to control lateral safety steering for lateral disturbance caused by lane departure warning, lane maintenance support and cross wind. This can be done integrally.

In addition, the present invention implements the lateral safety steering control for lane departure warning, lane maintenance support and lateral disturbance caused by lateral wind as a modular software, it is possible to electronically transform the lateral driving support system.

Hereinafter, with reference to the accompanying drawings will be described in more detail with respect to the transverse driving support system according to the present invention. 1 is a view showing a road model of the lateral driving support system according to the present invention, Figure 2 (a) and (b) is a view showing a vehicle model and a steering model of the lateral driving support system according to the present invention. .

First, an integrated state spatial equation used in a transverse driving support system capable of integrally controlling lane departure warning, lane keeping support, and lateral safety steering control according to the present invention will be described. This integrated state space equation is obtained using simplified road models, vehicle models, and steering models, and is modeled under the following assumptions.

① Do not consider the nonlinearity of tires and suspension systems by limiting the road on which the vehicle runs to highways or highways.

(2) Do not consider the yaw moment disturbance on the vehicle by assuming that cross winds act only on the center of the vehicle.

Meanwhile, the state variables and parameters shown in FIGS. 1 and 2 are defined as follows. α _h is the steering wheel angle, T _h is the driver torque, T _m is the assist torque, δ _f is the front wheel angle, ξ is the trail length, k _g is steering gear ratio, V is vehicle speed, β is slip angle, r is yaw rate, v is lateral velocity and y _f is departure distance from target line, θ _f is deviation angle from target line, ρ _f is lane curvature, Wr is lane width, P _c is vehicle's center gravity, P _i is camera observation View position of camera, K _f (K _r ) is the cornering power, I _f (I _r ) is the distance from vehicle's center gravity to front ( rear wheels), I is the vehicle yawing moment of inertia, and I _h is the equivalent moment of inertia of steering system. em).

First, as shown in FIG. 1, road information indicating a relative relationship between a driving lane and a vehicle obtained by acquiring an image of a Pi point by an image sensor such as a camera installed in the vehicle 10, and processing the variable or input value The road model can be expressed by Equation 1.

(식 1)

(Equation 1)

In addition, the vehicle model shown in (a) of FIG. 2 uses a two-wheeled vehicle model that does not consider the nonlinearity of the tire and the suspension as described above. As a result, a differential equation representing the vehicle model can be obtained as shown in Equation 2.

(식 2)

(Equation 2)

Here, φ is the transverse disturbance, and the transverse disturbance φ is expressed by the sum of the transverse disturbance (φ _cw ) and the transverse slope disturbance component (φ _rb ).

And, the steering model shown in (b) of Figure 2, the steering actuator 13 is mounted to the steering shaft 16 connected between the steering wheel 15 and the wheel 11, HPS 14 is a hydraulic power It consists of steering system. In addition, assuming that the steering model has a sufficiently large rigidity (that is, the front wheel angle δf = α _h / k _g ), an equation related to the steering model converted for the kingpin periphery is expressed by (Equation 3).

(Equation 3)

Here, the nonlinear relationship between Ts-> Tc is an approximation function of the hydraulic power steer.

이 되고, 이를 고려하여 위 (식 1), (식 2) 및 (식 3)을 종합하면 조향각속도, 조향각, 요레이트, 이탈각 및 이탈거리의 상태변수

를 가지는 통합상태공간방정식을 (식 4)와 같은 형태로 얻을 수 있다.As mentioned earlier, if you do not take into account the nonlinearity of the tires and suspension,

In consideration of this, the equations (1), (2) and (3) above are combined to determine the state variables of steering angle speed, steering angle, yaw rate, departure angle, and departure distance.

An integrated state-space equation with can be obtained in the form

(식 4)

(Equation 4)

는 횡가속도 센서(15, 도 3 참조)로부터 측정된 값을 의미한다. 그리고 (식 4)의 행렬에 포함되어 있는 파라미터들은 다음과 같이 정의될 수 있다.here,

Denotes a value measured from the lateral acceleration sensor 15 (see FIG. 3). The parameters included in the matrix of Equation 4 may be defined as follows.

By using the integrated state-space equation of Equation 4 according to the present invention, the torque for controlling the steering actuator is calculated and controlled by the output. For this purpose, the values of the state variables steering angle speed, steering angle, yaw rate, departure angle, and departure distance should be estimated using these information or obtained from sensors. To this end, the present invention has a configuration as shown in FIG. 3 is a view schematically showing a transverse driving support system according to the present invention.

Referring to FIG. 3, the transverse driving support system according to the present invention includes a road information extractor 20, an observer 30, and a controller 40. The road information extractor 20 extracts road information by image processing an image photographed by an image sensor 21 such as a camera mounted on the vehicle 10. In particular, it extracts information about the departure angle (θ _f ) and the departure distance (y _f ) required in the integrated state-space equation.

As shown in FIG. 4, which is a diagram illustrating a road information model used in the road information extractor 20, the image sensor 21 installed at the height H acquires an image of a driving lane with an inclination angle α. The road information extractor 20 recognizes the driving lane from the acquired image through various image processing processors to generate six left and right candidate points for the driving lane as shown in FIG. A departure angle θ _f , a departure distance y _f , and a curvature ρ _f are extracted. For this purpose, the road information extractor 20 uses a function defined as in Equation (5).

(식 5)

(Equation 5)

Where f is the focal length of the image sensor,

이다.

to be.

An algorithm for extracting road information (departure angle (θ _f ), departure distance (y _f ) curvature (ρ _f ), lane width (W _r ), and inclination angle (α)) using Equation 5 is given by Equation 6 It is designed as an extended kalman filter.

(식 6)

(Equation 6)

here,

,

,

,

,

이다.

to be.

P is the error covariance of X _s , R is the measurement noise variance, and Q is the covariance matrix of system noise.

Next, as shown in FIG. 3, the observer 30 includes sensors including a steering angle sensor 22, an inertial sensor 23, a vehicle speed sensor 24, a lateral acceleration line 25, and the like mounted on a vehicle. Information on the attitude and steering of the vehicle being driven is received from the vehicle, and the lateral speed v and the lateral disturbance component φ which are state variables are estimated using these information. Specifically, urate (r) is used.

Differential equations such as (7) are used for this purpose.

(식 7)

(Equation 7)

Since Eq. (7) satisfies the observability, the transverse velocity (v) and the transverse disturbance component (φ) and the transverse disturbance (φ _cw ) and the transverse gradient disturbance component (φ _rb ) are obtained according to (Equation 8). Become.

(식 8)

(Expression 8)

은 추정이득행렬이다.here,

Is the estimated gain matrix.

)를 추정한다.On the other hand, the observer 30 is a steering angular velocity (from the information related to the attitude and steering of the vehicle)

Estimate).

), 횡속도(v) 및 횡외란 성분(φ)인 횡풍외란(φ_cw)과 횡경사외란성분(φ_rb), 그리고 요레이트(r)를 사용하여 조향엑추에이터를 제어하는 조향토크(T_m)를 구한다. 조향토크(T_m)은 피이드백토크(

)와 횡풍 및 곡률에 대한 견인성 및 추종성을 결정하는 피이드포워드토크(

)로 구성되며 (식 9)에 의해서 구해진다. Finally, the control unit 40 is a departure angle (θ _f ) and departure distance (y _f ) extracted from the road information extractor 20 and the steering angle velocity estimated from the observer 30 (

Steering torque (T _m ), which controls the steering actuator using lateral wind (v) and transverse disturbance (φ _cw ), transverse disturbance (φ _rb ), and yaw rate (r). ) Steering torque (T _m ) is feedback torque (

) And feedforward torque to determine the traction and followability to transverse wind and curvature (

) And is obtained by (9).

(식 9)

(Eq. 9)

(식 10)

(Eq. 10)

는 상태 변수의 가중치를 나타낸다. Here, [ k ₁ k ₂ k ₃ k ₄ k ₅ k ₆ ] denotes the control gain of the feedback loop induced by LQ control theory (evaluation function) (Eq. 10), and k _f1 and k _{f2 correspond} to the cross wind. It means the control gain of the feedforward loop to reduce the influence and follow the curvature of the road. In (Eq. 10)

Denotes the weight of the state variable.

는 위 (식 10)에 대입되어 피이드백토크(

)를 구하는데 사용된다. Steering angle velocity, steering angle, yaw rate, departure angle and departure distance of the state variables of the integrated state-space equation

Is substituted into Eq. (10) and feedback torque (

Is used to find

The steering torque T _m thus obtained is used as the input value of the steering actuator 13 in the output means 50 shown in FIG. As a result, the road information detected by the vehicle, the attitude information and the steering information of the vehicle may be integrated to support the lateral driving of the vehicle.

On the other hand, the control unit 40 may control the steering actuator 13 to realize the lateral stability steering control, and at the same time may determine the departure of the lane to perform an alarm control to inform the driver. Specifically, the control unit 40 alerts the driver when there is a risk of departure of the lane so that the driver can recognize the driver and actively controls the vehicle, and at the same time, or the driver does not recognize the danger of leaving the lane. In this case, the lateral stability steering control can be performed by controlling the steering actuator 13.

The departure of the lane coordinate transforms the traveling direction of the vehicle 10 from the vehicle center point P to the departure reference point P _d as shown in FIG. 5, and the traveling direction of the vehicle 10 is also the departure reference point P _d. Parallel move to the center. The distance estimating distance between the traveling direction of the vehicle 10 and the point P _c meeting a given lane departure threshold line parallel to the traveling lane detected by the image sensor 21 based on the departure reference point P _d is estimated. Determined by the distance d _d .

Then, the departure estimation time t _d is calculated from the relationship between the departure estimation distance d _d and the vehicle speed V provided by the vehicle speed sensor 24. Then, when the vehicle reaches the vehicle departure threshold and there is a risk of departure, the controller 40 alerts using the alarm device 51, HMI, speaker, and vibration device. Here, the vibration device uses a haptic device to give a vibration to the seat belt of the driver.

Meanwhile, the controller 40 may divide the vehicle departure threshold into a plurality of distances according to the distance, divide the risk of colliding with the plurality of vehicle departure thresholds into a plurality, and use another alarm device 51 according to the risk. For example, when the risk is low, the driver is visually alerted only by the HNI device, and as the risk increases, the speaker is audible and the vibration device is a tactile alarm.

As described above, the present invention utilizes an integrated state-space equation with state variables of steering angle speed, steering angle, yaw rate, departure angle, and departure distance, for lane departure warning, lane maintenance support, and transverse disturbance caused by cross wind. Lateral safety steering control can be integrated.

In addition, the present invention implements the lateral safety steering control for lane departure warning, lane maintenance support and lateral disturbance caused by lateral wind as a modular software, it is possible to electronically transform the lateral driving support system.

1 is a view showing a road model of the transverse driving support system according to the present invention.

2 (a) and 2 (b) are diagrams illustrating a vehicle model and a steering model of the lateral driving support system according to the present invention.

3 is a view schematically showing a transverse driving support system according to the present invention.

4 is a view for explaining a road information acquisition method used in the road information extractor according to the present invention.

5 is a diagram illustrating a lane departure determining method according to the present invention.

<Description of Symbols for Main Parts of Drawings>

10: vehicle 13: steering actuator

20: road information extractor 21: steering angle sensor

23: inertial sensor 24: vehicle speed sensor

25: lateral acceleration sensor 30: observer

40: control unit 50: output means

Claims (5)

A road information extractor for extracting road information including a departure angle and a departure distance of the vehicle from an image obtained through an image sensor installed in the vehicle, Observer which receives information related to vehicle attitude and steering from sensors installed in the vehicle and estimates steering related information including steering angle speed, transverse velocity and lateral disturbance caused by draft Control unit for calculating steering torque by using the road information and steering related information from the road information extractor and the observer in an integrated state space equation with steering angle speed, steering angle, lateral speed, yaw rate, departure angle and departure distance as state variables , And And a steering actuator controlled by an output signal of the steering torque transmitted from the control unit. The method of claim 1, The control unit, Before the output signal of the steering torque is output, a distance estimating distance of the vehicle is calculated from the road information and compared to the speed of the vehicle, the vehicle is separated into a plurality of risks according to the degree of departure from the lane and according to the plurality of risks. Transverse driving assistance system, characterized in that for generating a control signal for controlling the alarm of different types. The method of claim 2, The alarm device is a lateral driving support system, characterized in that the HMI device for real-time notification of the operating state of the lateral driving support system, a speaker that acoustically warns and a vibrating device that gives vibration to the driver tactilely. The method according to any one of claims 1 to 3, The sensors installed in the vehicle include a lateral acceleration sensor for measuring the lateral acceleration, a steering angle sensor for measuring the steering angle of the steering wheel, an inertial sensor for measuring the yaw angle, and a vehicle speed sensor for measuring the speed of the vehicle. Driving assistance system. Extracting road information including a departure angle and a departure distance of the vehicle from an image obtained through an image sensor installed in the vehicle, Estimating steering related information including steering angular velocity, lateral velocity, and transverse disturbance caused by draft by using values related to vehicle attitude and steering from sensors installed in the vehicle, Calculating steering torque by using the road information and steering related information in an integrated state spatial equation using steering angle speed, steering angle, lateral speed, yaw rate, deviation angle, and deviation distance as state variables; Calculating a distance estimating distance of the vehicle from the road information and alerting the driver according to the degree of the vehicle leaving the lane, in contrast to the speed of the vehicle, and And controlling a steering actuator with the calculated steering torque.

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