KR101899393B1 - Method for second collision avoidance of vehicle - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary collision avoidance method for a vehicle, and more particularly, it relates to a secondary collision avoidance method for a vehicle, which, when a rear collision is determined to be reliable through a sensor mounted on a vehicle, And to stabilize the behavior of the vehicle after the collision to avoid additional collision.
A second collision avoidance method of a vehicle according to the present invention includes the steps of receiving a sensor value for a relative distance and a relative speed with respect to a nearby vehicle through a sensor mounted on the vehicle; Calculating collision risk using the input sensor value; Checking whether the neighboring vehicle has entered a predetermined minimum detection distance using the input longitudinal direction relative distance and the lateral direction relative distance when the calculated collision risk is out of a predetermined value; Estimating a state variable immediately before the collision using the longitudinal relative distance and the transverse direction relative distance with the surrounding vehicle when the nearby vehicle has entered the minimum detection distance; Estimating a state variable immediately after the collision using the crash state variable and the crash model; And applying a biased braking input to the vehicle in a direction to reduce the rotational angular velocity of the estimated state variable immediately after the collision; .

Description

METHOD FOR SECOND COLLISION AVOIDANCE OF VEHICLE < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary collision avoidance method for a vehicle, and more particularly, it relates to a secondary collision avoidance method for a vehicle, which, when a rear collision is determined to be reliable through a sensor mounted on a vehicle, And to stabilize the behavior of the vehicle after the collision to avoid additional collision.

According to the traffic accidents statistics of the last three years, 14% of the total deaths were caused by the second collision, and the mortality rate by the second collision was about 50%, which is about 3.3 times higher than the average mortality rate of 15.3% Respectively.

The reason for the high mortality rate due to the secondary collision is that the damage caused by the secondary collision is added to the damage after the primary collision, and the scale of the collision is increased.

As a result, in order to reduce the number of traffic accident deaths caused by the second collision, the second collision avoidance system has been actively studied since 2010.

A study on the existing second collision avoidance system shows that most of them are post-control type that secure the stability of the vehicle through steering and braking coordination control after the first collision.

However, there are two limitations in ensuring vehicle stability through post-control.

The first limitation is the possibility of breakage and malfunction of the sensor and the actuator. Most of the sensors used to control the behavior of the vehicle are likely to fail to perform their normal function after the first collision because they are vulnerable to impact.

In addition, most of the actuators used for steering and braking control are electric actuators, and there is a high possibility of breakage and malfunction due to problems such as disconnection or short-circuit of the control device due to impact.

The second limitation is uncertainty about the driver's driving pattern immediately after the first impact. It is difficult to predict which steering and braking input the driver will apply after the first collision, and when the driver's driving pattern and the steering and braking inputs due to the post-control conflict, the stability of the vehicle is rather unstable, Of the population.

Korean Patent No. 10-0751635 Korean Patent No. 20-0476749

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle which can stabilize the behavior of a vehicle after a collision by avoiding additional collision by balancing the behavior of the vehicle, The second collision avoidance method of the present invention.

A second collision avoidance method of a vehicle according to the present invention includes the steps of receiving a sensor value for a relative distance and a relative speed with respect to a nearby vehicle through a sensor mounted on the vehicle; Calculating collision risk using the input sensor value; Checking whether the neighboring vehicle has entered a predetermined minimum detection distance using the input longitudinal direction relative distance and the lateral direction relative distance when the calculated collision risk is out of a predetermined value; The longitudinal relative distance and the transverse direction relative distance at the moment when the adjacent vehicle has reached the minimum detection distance are substituted into the recursive equation to determine the longitudinal relative distance and the transverse direction right before the collision, Estimating a velocity at a point immediately before the collision and a point immediately before the collision as a state variable immediately before the collision using the estimated longitudinal relative distance and the estimated lateral relative distance after estimating the direction relative distance; Estimating a state variable immediately after the collision using the crash state variable and the crash model; And applying a biased braking input to the vehicle in a direction to reduce the rotational angular velocity of the estimated state variable immediately after the collision; .

In the present invention, the collision risk (TTC _x , TTC _y ) is implemented as follows, where RD _x , RV _x denote longitudinal relative distances and velocities, RD _y and RV _y denote transverse relative distances and velocities .

, 횡방향 속도

, 회전 각속도

이며, 재귀 방정식을 통해 계산된 충돌 직전의 종/횡방향 상대거리 RD_x, RD_y 가 0이 되는 충돌 시점 t_c로부터 추정된다.In the present invention, the " immediately before impact "

, Transverse speed

, Rotational angular velocity

And the longitudinal / transverse relative distances RD _{x and} RD _y immediately before the collision calculated through the recursive equation Lt; RTI ID = _0.0 > tc < / RTI >

, 횡방향 속도

, 회전 각속도

이며, 상기 충돌 직전 상태 변수

,

,

와 Branch의 충돌 모델을 이용하여 추정된다.In the present invention,

, Transverse speed

, Rotational angular velocity

, And the immediately preceding crash state variable

,

,

And the collision model of the branch.

가 감소하는 방향으로 회전 각속도

를 추정하여 아래 수식을 만족할 때까지 입력되고, 이 때

는 편제동의 개입량 결정 인자로 0~1 사이의 값 중 선택된다.In the present invention, the pre-braking input is a time (t _c - t) obtained by subtracting the anticipated braking control execution execution time t _e from the collision time t _c , t _e ), wherein the pre-crash input is made via the pre-crash pre-crash braking input to the post-

The rotational angular velocity

Is inputted until the following expression is satisfied, and at this time

Is determined as a decision variable between 0 and 1,

According to the present invention, since the pivotal braking is performed using the actuator in the normal operation immediately before the first collision, the damage such as malfunction due to the component damage due to the impact of the first collision can be minimized.

Also, since the risk of the second collision is minimized by minimizing the steering input applied by the driver in order to stabilize the vehicle after the first collision, there is an advantage that the collision stability of the vehicle can be secured regardless of the driver's propensity and driving ability.

FIG. 1 is an example of a secondary collision avoiding situation in a pre-control method according to an embodiment of the present invention.
2 is a flowchart of a second collision avoidance method of a vehicle according to an embodiment of the present invention.
3 is an exemplary graph of longitudinal / transverse relative distance estimation using a recursive equation according to an embodiment of the present invention.
4 is a diagram illustrating simulation conditions for verifying performance of a second collision avoidance method of a vehicle according to an embodiment of the present invention.
5 is a view showing a simulation result in a state where the second collision avoidance method of the vehicle is not applied.
6 is a diagram showing a simulation result of a state in which a second collision avoidance method of a vehicle is applied.
FIG. 7 is a diagram showing a result of a braking control of performance verification of a second collision avoidance method of a vehicle according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

FIG. 1 is an example of a secondary collision avoiding situation in a pre-control method according to an embodiment of the present invention.

Referring to FIG. 1, the target vehicle 120 monitors the risk of collision with the rear vehicle 110 through the rear mounted distance sensor and the speed sensing sensor 121 in (a).

When the risk of collision with the rear vehicle 110 is detected during monitoring, the collision prediction is performed and the braking for minimizing the damage due to the secondary collision is performed in the direction shown in (b).

(c), when the collision occurs immediately after the braking is performed, the target vehicle 120 can avoid the secondary collision with the side vehicle 130 in the left direction while the behavior in the direction of the braking is canceled by the change in behavior due to the collision do.

If a collision occurs in the state where the braking is not performed, the target vehicle 120 may be struck to the left side due to collision of the right side, as shown in (d), and a second collision with the side vehicle 130 may occur. The driver would have difficulty controlling the behavior of the vehicle.

The pre-control method for minimizing the damage caused by the second collision will be described in more detail.

2 is a flowchart of a second collision avoidance method of a vehicle according to an embodiment of the present invention.

Referring to FIG. 2, a peripheral vehicle is first monitored through a sensor mounted on a vehicle, and a sensor value for a relative distance and a relative speed is input (S101).

The sensor can be applied to any sensor that can measure distance and speed, and a distance sensor using an acceleration sensor and an ultrasonic wave or a laser is generally used, but a video sensor such as a camera may be used.

It is desirable that the relative distance and the relative speed are input in both the longitudinal direction and the lateral direction.

When the sensor value of the surrounding vehicle is inputted in this way, the collision risk is calculated using the sensor value (S103).

At this time, the risk of collision can be calculated by the following equation according to the ratio of the relative speed to the relative vehicle and the relative distance.

및

는 종방향 및 횡방향에 대한 충돌 위험도를 나타내며,

와

는 종방향 및 횡방향에 대한 상대거리를 나타내고,

와

는 종방향 및 횡방향에 대한 상대속도를 나타낸다.In the above formula

And

Represents the risk of collision for longitudinal and transverse directions,

Wow

Represents the relative distance to the longitudinal direction and the lateral direction,

Wow

Represents the relative speed with respect to the longitudinal direction and the lateral direction.

The risk of collision according to the above formula is in a dangerous state as the number is lower. For example, when the relative speed is 10 m / h and the relative distance is 10 m or 20 m, the collision risk is calculated as 1 and 2, It is intuitively known that the closer the distance is, the higher the risk of collision, so the lower the risk of collision, the more dangerous it is.

If it is determined that the calculated risk of collision is out of a preset value, that is, it is determined that the probability of collision is increased by lowering to a predetermined threshold value or lower, the relative vehicle distance and the lateral relative distance inputted from the sensor are used, It is confirmed whether or not it has reached the detection distance (S105).

The minimum detection distance is determined in consideration of the minimum detection range (MDR) of the sensor, and confirms the moment when the nearby vehicle enters the MDR.

If the neighboring vehicle has reached the minimum detection distance, a state variable immediately before the collision is estimated using the longitudinal relative distance and the lateral direction relative distance with respect to the neighboring vehicle measured through the sensor (S107).

In order to estimate the state variables immediately before the collision, the longitudinal relative distance and the transverse direction relative distance should be extracted.

For this purpose, longitudinal / transverse relative distances of the moment when the vehicle approaches within the predetermined minimum detection distance are substituted into the recursive equation to extract the longitudinal relative distance and the transverse direction relative distance immediately before the collision.

For the vehicle judged to be a dangerous vehicle, longitudinal and lateral relative distances measured from the sensor are input to the instant recursive equation within the MDR and extracted as longitudinal / transverse relative distance information immediately before the collision.

An example graph of the longitudinal / transverse relative distance estimation using the recursive equation is shown in FIG.

Referring to FIG. 3, the graph above is a longitudinal relative distance estimation graph obtained through a recursive equation, and the following graph is a lateral direction relative distance estimation graph.

The longitudinal relative distance was monitored from around 27 m and it was observed at 5 m at 0 s and it was judged that it entered MDR. The longitudinal relative distance at this time can be substituted into the recursive equation to predict the point immediately before the collision.

The lateral relative distance is monitored at a value close to 0 m, which indicates that there is almost no distance angle between the surrounding vehicle and the target vehicle, and the lateral relative distance based on 0 second when the longitudinal relative distance enters the MDR It is possible to predict the point immediately before the collision by substituting it into the recursive equation.

In FIG. 3, a collision was predicted 0.2 seconds after entering the MDR.

When the longitudinal relative distance and the lateral relative distance and the collision time are known, the speed at the point immediately before the collision can be known.

, 횡방향 속도

, 회전 각속도

이며, 다음으로 이렇게 추정된 충돌 직전 상태 변수와 충돌 모델을 이용하여 충돌 직후 상태 변수를 추정한다(S109).Referring back to FIG. 2, the estimated velocity can be represented by a state variable,

, Transverse speed

, Rotational angular velocity

Next, a state variable is estimated immediately after the collision using the estimated state variable and the collision model (S109).

, 횡방향 속도

, 회전 각속도

으로 나타낼 수 있으며, 충돌 직전 상태 변수

,

,

와 Branch의 충돌 모델을 이용하여 추정할 수 있다.Immediately after the collision,

, Transverse speed

, Rotational angular velocity

, And the state before the collision

,

,

And a collision model of a branch.

The collision model of a branch is a proven model that has already been widely used in the field of accident analysis. It assumes that the vehicle is a two-degree-of-freedom rigid body on the plane and allows to estimate the state variables immediately after the collision when the state variables immediately before the collision are known.

Since the 3-DOF collision model of the branch and the estimation method using the vehicle model are already known, detailed estimation steps are not described in the present invention.

, 횡방향 속도

, 회전 각속도

가 구해지면 계산된 회전 각속도를 감소시키는 방향으로 차량에 편제동 입력을 가한다(S111).Using the collision model of the branch,

, Transverse speed

, Rotational angular velocity

(Step S111). In step S111, the vehicle speed is set to a predetermined value.

The control strategy for the pre-control based secondary collision avoidance system can be classified into four types as shown in FIG.

The first control strategy is to accelerate the vehicle just before the collision. This method can alleviate the first collision damage, but accelerating the vehicle without the driver's acceleration command does not apply to the present invention because it may cause legal problems.

In the second control strategy, the vehicle is decelerated immediately before the collision. This method reduces the probability of a secondary collision but it is better to exclude it because it has the potential to increase the damage of the primary collision.

가 증가하는 방향으로 조향 및 편제동 입력을 가하는 것이다. 이 방법은 1차 충돌의 피해를 감소시킬 수 있지만 충돌 이후

가 증가되어 미숙한 운전자의 경우 차량 제어성을 잃어버릴 수 있을 뿐만 아니라, 충돌 이후에 차량이 인접차선으로 넘어가 또 다른 2차 충돌을 유발 할 수 있으므로 제외한다.In the case of the third control strategy,

And the steering and braking input is applied in the direction in which the braking force increases. This method can reduce the damage of the primary collision, but after the collision

Is increased, so that an inexperienced driver can not only lose control of the vehicle, but also exclude a vehicle after collision because it may cause another secondary collision to pass to the adjacent lane.

가 감소하는 방향으로 편제동 입력을 가하는 것이다. 이 방법은 1차 충돌의 피해가 다소 증가할 수는 있지만 충돌 이후에 운전자가 차량을 빠르고 안정적으로 제어할 수 있으며, 충돌 이후에 차선을 유지할 확률이 증가하여 2차 충돌이 일어날 확률을 감소시켜 준다.Finally, the fourth control strategy is to

Is applied in a direction in which the braking force is decreased. This method allows the driver to control the vehicle quickly and steadily after the collision, although the damage of the primary collision may increase somewhat, and the probability of maintaining the lane after the collision increases, reducing the probability of secondary collision .

가 감소하는 방향 즉, 충돌에 의한 차량의 조향각 변화를 최소화하기 위한 방향으로

를 결정하여 편제동 입력을 수행한다.Therefore, in the present invention, the rotation angular velocity

In the direction of decreasing the steering angle of the vehicle due to the collision

And performs a one-shot braking input.

The time point at which the one-shot braking input is performed can be calculated using the collision time predicted through the recursive spinning equation in FIG.

가 감소하는 방향으로 회전 각속도

를 추정하여 아래 수식을 만족할 때까지 입력되고,

의 부호에 따라 왼쪽/오른쪽 중 한쪽에만 가해진다.The pre-braking input is calculated by subtracting the anticipated braking control execution expected time t _e from the collision time t _c (t _c - t _e ), and the unilateral braking pressure is determined by the state variable immediately after the predicted collision

The rotational angular velocity

Lt; / RTI > is input until the following equation is satisfied,

Are applied to only one of the left and right sides according to the sign of < RTI ID = 0.0 >

는 편제동의 개입량 결정 인자로 0~1 사이의 값 중 선택되는데 2차 충돌 회피 시스템의 소극적인 개입과 적극적인 개입에 대한 개발 목표에 따라 변경이 가능한 값이다.At this time,

Is a value determined between 0 and 1, which is a value that can be changed according to the development goals of passive intervention and active intervention of the secondary collision avoidance system.

The second collision avoidance method of the vehicle through these steps needs to verify its performance through application of the collision scenario.

In order to verify the performance of the second collision avoidance method of the vehicle, a simulation condition in which a vehicle traveling at 85 km / h from the rear as shown in FIG. 4 collides with the right rear of the vehicle traveling at 60 km / h at 25% Respectively.

FIG. 5 shows simulation results of the vehicle in which the second collision avoidance method is not applied, and FIG. 6 shows simulation results of the applied state.

First, referring to FIG. 5, in a vehicle to which the second collision avoidance method of the vehicle is not applied, the driver performs maximum braking after 0.5 seconds based on 1 second, which is the time point at which the first collision occurs, However, it is not possible to recover the stability of the vehicle quickly, and it can be confirmed that the vehicle is passing to the adjacent lane to the left or right. Such a result is likely to cause a second collision with the vehicle in the adjacent lane.

의 크기가 감소하여, 운전자가 차량 안정성을 빠르게 확보하는 것을 확인할 수 있다.On the other hand, referring to FIG. 6, it can be seen that the vehicle to which the second collision avoidance method of the vehicle is applied is to apply the pre-braking force to the right wheel about 0.3 seconds before the first collision occurs, After the car crash

It is possible to confirm that the driver quickly secures the stability of the vehicle.

Looking at the trajectory of the vehicle, it can be seen that it keeps the driving lane well and the braking distance is shorter by about 10 m than the vehicle which does not have the braked vehicle applied.

FIG. 7 is a diagram showing a result of a braking control of performance verification of a second collision avoidance method of a vehicle according to an embodiment of the present invention.

를 발생시켜 충돌 이후에 발생하는

의 크기를 감소시키기 때문에 운전자는 상대적으로 안정성이 확보된 상태의 차량을 제어하게 됨으로써, 1차 충돌 이후 차량 안정성을 빠르게 확보할 수 있다.Looking at the piece of Figure 7, the result of the braking control, in the negative direction for approximately 0.3 seconds, t _e about 15deg / s

Which occurs after the collision

The driver can control the vehicle in a relatively stable state, so that the stability of the vehicle can be secured quickly after the first collision.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments. Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope of the appended claims, The genius will be so self-evident. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

110: rear vehicle 120: target vehicle
121: distance and speed detection sensor 130: side vehicle

Claims (5)

Receiving a sensor value for a relative distance and a relative speed with a surrounding vehicle through a sensor mounted on the vehicle;
Calculating collision risk using the input sensor value;
Checking whether the neighboring vehicle has entered a predetermined minimum detection distance using the input longitudinal direction relative distance and the lateral direction relative distance when the calculated collision risk is out of a predetermined value;
The longitudinal relative distance and the transverse direction relative distance at the moment when the adjacent vehicle has reached the minimum detection distance are substituted into the recursive equation to determine the longitudinal relative distance and the transverse direction right before the collision, Estimating a velocity at a point immediately before the collision and a point immediately before the collision as a state variable immediately before the collision using the estimated longitudinal relative distance and the estimated lateral relative distance after estimating the direction relative distance;
Estimating a state variable immediately after the collision using the crash state variable and the crash model; And
Applying a braking input to the vehicle in a direction to reduce the rotational angular velocity of the estimated state variable immediately after the collision; And the second collision avoidance method of the vehicle. The method according to claim 1,
Wherein the collision risk (TTC _x , TTC _y ) is implemented as: RD _x , RV _x denotes the longitudinal relative distance and velocity, RD _y and RV _y are the vehicle's lateral relative distance and velocity Secondary collision avoidance method.

The method according to claim 1,
The pre-crash state variable may be a longitudinal velocity

, Transverse speed

, Rotational angular velocity

And the longitudinal / transverse relative distances RD _{x and} RD _y immediately before the collision calculated through the recursive equation Is zero, is estimated from the collision time t _c . The method of claim 3,
The state variable immediately after the collision is a longitudinal velocity

, Transverse speed

, Rotational angular velocity

, And the immediately preceding crash state variable

,

,

And a second collision avoidance method of a vehicle estimated using a collision model of a branch. 5. The method of claim 4,
The pre-braking input is calculated by subtracting the anticipated braking control execution expected time t _e from the collision time t _c (t _c - t _e ), and the knee braking input is performed after the collision predicted through the pre-crash braking input

The rotational angular velocity

Is inputted until the following expression is satisfied, and at this time

Is a decision factor for the amount of intervention of the vehicle, and is selected from a value between 0 and 1. [

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