KR101478068B1 - Apparatus for preventing collision in vehicle and method thereof - Google Patents

Abstract

An apparatus for preventing vehicle collision and a method thereof are disclosed. A vehicle collision avoidance apparatus according to an embodiment of the present invention includes a front sensing sensor for sensing a distance to a front vehicle, a relative speed and a relative acceleration, a warning unit for warning of a risk of collision with a preceding vehicle, The collision risk of each model is determined from the vehicle speed models indicating a plurality of dynamic situations between the vehicle and the preceding vehicle, and the final collision risk, which is the sum of the determined collision risks, is determined, And an electronic control unit for warning of the risk of collision with the preceding vehicle based on the final collision risk.

Description

[0001] APPARATUS FOR PREVENTING COLLISION IN VEHICLE AND METHOD THEREOF [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and a method for preventing a vehicle collision, and more particularly, to an apparatus and method for preventing a vehicle collision that can reduce the risk of collision with a preceding vehicle.

Generally, the safety distance to the preceding vehicle for preventing the collision of the vehicle is defined by the speed of each vehicle. A low vehicle speed requires a short braking distance, but a vehicle traveling at high speed will require a longer braking distance.

However, in a situation where it is difficult to confirm the position of the preceding vehicle during the operation of the vehicle, it is not easy for the driver to maintain such a safety distance. In other words, if the vehicle interval is not maintained at the braking distance in spite of sudden braking immediately before the collision with the preceding vehicle, the collision can not be avoided.

Therefore, in order to prevent collision and safe operation of the vehicle, it is inevitably necessary to secure a safety distance to cope with the sudden situation of the preceding vehicle.

2. Description of the Related Art [0002] Recently, a system for preventing various safety accidents that may occur during driving of a vehicle has been developed and mounted on a vehicle. In the related art, a front collision preventing device . Such a vehicle collision prevention apparatus is an apparatus for securing the safety of a vehicle and a driver at the time of changing a driving lane of a vehicle, and uses an ultrasonic sensor or a laser radar to detect the presence of a preceding vehicle having a possibility of collision.

In the past, the collision risk measurement method has been combined with the time to contact (TTC) between the vehicle and the preceding vehicle and the distance to contact (DTC) between the vehicle and the preceding vehicle, .

In addition, the driver can be insensitive to the alarm because the driver is alerted even though the driver is aware of the danger.

An embodiment of the present invention is to provide a vehicle collision avoidance apparatus and method for judging a collision risk according to various dynamic conditions with a forward vehicle and diversifying a warning method according to whether the driver is at risk or not.

According to an aspect of the present invention, there is provided a vehicular navigation system including: a front sensing sensor for sensing a distance to a front vehicle, a relative speed, and a relative acceleration; A warning unit for warning of a risk of collision with the preceding vehicle; And a controller for receiving sensor information input from the front sensing sensor and determining collision risk for each model from vehicle speed models representing a plurality of dynamic situations between the vehicle and the preceding vehicle, And an electronic control unit for determining a collision risk and warning a risk of collision with the preceding vehicle based on the determined final collision risk, A constant acceleration model, a constant-velocity model in which the vehicle is assumed to travel at a constant speed, or a non-negative acceleration model in which the vehicle is assumed to travel in non-negative acceleration, The estimated collision time (TTC) and the expected collision distance (DTC) are calculated for each model, A vehicle collision avoiding apparatus may be provided which determines collision risk for each model by using the estimated collision time (TTC) and the collision predicted distance (DTC).

The electronic control unit calculates the probability density function (PDF) and the cumulative distribution function (CDF) using the collision predicted time (TTC) and the collision predicted distance (DTC) And determining the risk of collision, respectively, in accordance with the density function (PDF) and the cumulative distribution function (CDF).

In addition, the electronic control unit performs a warning made up of a combination of a video warning, an audio warning, and a vibration warning in accordance with the determined final collision risk, and carries a warning to the driver Determining whether the risk of collision of the driver accompanying the operation is a risk, and changing the warning combination if it is determined that the driver recognizes the risk of collision.

And a plurality of vehicle sensors for sensing a vehicle speed, an acceleration, a steering angle, a yaw rate, a lateral acceleration, and a brake pedal pressure of the vehicle, wherein the electronic control unit calculates a differential If the absolute value of the value is less than the absolute value of the sensed acceleration and the sensed brake pedal pressure exceeds the reference pressure and the sensed yaw rate exceeds the reference yaw rate, can do. The reference yaw rate is an absolute value of a value obtained by multiplying the differential value of the sensed steering angle by the sensed vehicle speed divided by the vehicle length.

According to another aspect of the present invention, there is provided a vehicle speed control apparatus that receives sensor information input from a front sensing sensor that senses a distance to a forward vehicle, a relative speed and a relative acceleration, receives a vehicle speed model representing a plurality of dynamic situations between the vehicle and the preceding vehicle A risk of collision with the preceding vehicle based on the determined final collision risk, and a risk of collision with the preceding vehicle based on the determined final collision risk, The speed model is a constant acceleration model in which the vehicle is assumed to travel at a constant acceleration, a constant-speed model in which the vehicle is assumed to travel at a constant speed, or a non-negative acceleration in which the vehicle is assumed to travel at non- And determining at least one of the plurality of models, A collision avoidance time (TTC) and a collision anticipated distance (DTC) are calculated for each of the models, and a collision risk is determined based on the calculated collision anticipated time (TTC) and the collision anticipated distance (DTC) A method can be provided.

The determination of the collision risk for each model may be performed by using a probability density function (PDF) and a cumulative distribution function (CDF) using the collision prediction time (TTC) and the collision prediction distance (DTC) And determining the risk of collision, respectively, in accordance with the calculated probability density function (PDF) and cumulative distribution function (CDF), respectively.

In addition, it is also possible to perform a warning consisting of a combination of a video warning, an audio warning, and a vibration warning in accordance with the determined final collision risk, and a driver who carries a vehicle operation to reduce the risk of collision , And changing the warning combination if it is determined that the driver recognizes the risk of collision as a result of the determination.

The absolute value of the differential value of the vehicle speed sensed by the plurality of vehicle sensors for sensing the vehicle speed, the acceleration, the steering angle, the yaw rate, the lateral acceleration, and the brake pedal pressure of the vehicle is less than the absolute value of the sensed acceleration And determining that the driver is aware of the risk of collision if the sensed brake pedal pressure exceeds a reference pressure and the sensed yaw rate exceeds a reference yaw rate. The reference yaw rate is an absolute value of a value obtained by multiplying the differential value of the sensed steering angle by the sensed vehicle speed divided by the vehicle length.

In the embodiment of the present invention, various dynamic situations with respect to the preceding vehicle are set, and the collision expected time (TTC) between the vehicle and the preceding vehicle and the expected collision distance (DTC) between the preceding vehicle and the preceding vehicle are calculated, It can be alarmed by reflecting various dangerous situations that the driver may feel.

Further, in the embodiment of the present invention, the driver can set an alarm threshold value for each dangerous situation, so that the risk of collision can be changed according to driving propensity or preference.

In the embodiment of the present invention, since it is determined whether or not the driver is dangerous and the alarm means and the alarm amount are adjusted accordingly, it is possible to prevent an accident that may occur due to the driver not being aware of the warning.

1 is a control block diagram of a vehicle collision avoidance apparatus according to an embodiment of the present invention.
2 is a view showing a distance between a vehicle equipped with a vehicle collision avoidance apparatus and a preceding vehicle according to an embodiment of the present invention.
3 is a control flowchart for a method of controlling a vehicle collision avoidance apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are provided by way of example so that those skilled in the art will be able to fully understand the spirit of the present invention. The present invention is not limited to the embodiments described below, but may be embodied in other forms. In order to clearly explain the present invention, parts not related to the description are omitted from the drawings, and the width, length, thickness, etc. of the components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

The expression "and / or" is used herein to mean including at least one of the elements listed before and after. Also, the expression "coupled / connected" is used to mean either directly connected to another component or indirectly connected through another component. The singular forms herein include plural forms unless the context clearly dictates otherwise. Also, components, steps, operations and elements referred to in the specification as " comprises "or" comprising " refer to the presence or addition of one or more other components, steps, operations, elements, and / or devices.

1 is a control block diagram of a vehicle collision avoidance apparatus according to an embodiment of the present invention. 2 is a view showing a distance between a vehicle equipped with a vehicle collision avoidance apparatus and a preceding vehicle according to an embodiment of the present invention.

1 and 2, the vehicle collision avoidance apparatus may include a sensing unit 10, an electronic control unit 20, a brake unit 30, and a warning unit 40.

The sensing unit 10 senses various sensor information of the vehicle and includes a front sensing sensor 11, a vehicle speed sensor 12, a steering angle sensor 13, a yaw rate sensor 14, a lateral acceleration sensor 15, An accelerator pedal sensor 16, and a brake pedal sensor 17.

The front detection sensor 11 is installed in front of the vehicle and is composed of various known sensors such as a radar and a camera so that the distance between the vehicle C1 and the front vehicle C2 The relative speed and the relative acceleration between the vehicle D and the preceding vehicle C1 and the preceding vehicle C2 are detected and transmitted to the electronic control unit 20. [

The vehicle speed sensor 12 is installed in each of the wheels FL, RR, RL and FR of the vehicle to sense the speed of the vehicle according to the speed of the wheels FL, RR, RL and FR. The vehicle speed signal sensed by the vehicle speed sensor 12 is input to the electronic control unit 20. [

The acceleration sensor 13 senses the acceleration of the vehicle. The acceleration signal sensed by the acceleration sensor 13 is input to the electronic control unit 20. [

The steering angle sensor 14 senses the degree of steering of the vehicle. The steering angle signal sensed by the steering angle sensor 14 is input to the electronic control unit 20. [

The steering angle sensor 14 is mounted at the lower end of the steering wheel and detects the steering angle of the steering wheel to steer the steering wheel and determine whether the steering wheel is steered by the driver when the vehicle is yaw.

The steering angle sensor 14 also detects the steering speed and the steering direction of the steering wheel. When the steering angle sensor 14 is steered by the optical element method, the slit plate of the sensor rotates while passing or blocking the light of the optical device, and the voltage is changed. The steering angle sensor 14 receives the steering angle, steering direction, The steering angle is detected.

The yaw rate sensor 15 detects the yaw rate (turning speed) of the vehicle and transmits it to the electronic control unit 20.

The yaw rate sensor 15 electronically detects the yaw moment of the vehicle while causing the internal fork of the internal vibration to change when the vehicle rotates about the vertical axis, i.e., about the Z axis direction. Here, the yaw moment is the force that the front and rear of the vehicle body move to the left or right or the inner, outer wheel when turning. The yaw rate sensor 15 has a structure in which a cesium crystal element is disposed inside and when the vehicle rotates while the vehicle moves, a voltage is generated while rotating the element itself.

The lateral acceleration sensor 16 is a two-axis acceleration sensor that detects the lateral acceleration (Lateral-G) of the vehicle, which is an acceleration of a force that the vehicle is about to sideways while the vehicle is running, and transmits it to the electronic control unit 20.

The accelerator pedal sensor 17 detects whether the accelerator pedal is operated and transmits it to the electronic control unit 20.

The brake pedal sensor 18 senses whether or not the brake pedal is operated according to the braking intention of the driver and senses the brake pedal pressure in response to the pedal depression of the driver and transmits it to the electronic control unit 20. [

The electronic control unit 20 determines the risk of collision according to various dynamic conditions of the vehicle C1 and the preceding vehicle C2 by receiving various sensor information transmitted from the sensing unit 10, Diversify the warning method accordingly, and control to perform automatic braking if necessary.

The electronic control unit 20 also warns the driver of the risk of collision with the preceding vehicle based on the determined collision risk using visible warning, audible warning, haptic warning, , Determines that the driver recognizes the danger, and changes the alarm combination and / or alarm amount accordingly.

Further, the electronic control unit 20 determines the amount of brake assist corresponding thereto based on the determined collision risk, and controls the braking force of the brake portion 30 based on the determined amount of brake assist.

The brake unit 30 controls the brake fluid pressure supplied to the wheel cylinder in accordance with the brake signal output from the electronic control unit 20 to generate a braking force to prevent the vehicle from colliding with the wheel cylinder.

The warning unit 40 alerts the risk of collision between the vehicle C1 and the preceding vehicle C2 in accordance with the warning signal output from the electronic control unit 20. [ The warning unit 40 alerts the risk of collision with the preceding vehicle by using a warning method such as a video warning, an audio warning, and a vibration warning.

Hereinafter, it will be described in more detail how the electronic control unit 20 judges the collision risk according to various dynamic situations of the vehicle C1 and the front vehicle C2, and diversifies the warning method according to whether the driver is at risk or not.

The electronic control unit 20 receives the various sensor information transmitted from the sensing unit 10 and determines the risk of collision according to various dynamic conditions of the vehicle C1 and the vehicle C2.

The risk of collision felt by the driver depends on the dynamic situation with the front vehicle. The dynamic situation with the forward vehicle can be defined as a plurality of dynamic situations according to changes in the vehicle speed and acceleration.

A plurality of dynamic situations may include three models.

For example, the first of the three models is a constant acceleration model, the second model is a constant velocity model, the third model is a non-negative acceleration model.

The constant acceleration model may mean a vehicle speed model in which the vehicle is assumed to travel at a constant acceleration and the constant speed model may mean a vehicle speed model in which the vehicle is assumed to travel at a constant speed, The model may refer to a vehicle speed model in which the vehicle is assumed to travel at a non-negative acceleration.

The electronic control unit 20 calculates a collision expected time (TTC) and a collision predicted distance (DTC) between the car and the preceding vehicle under a plurality of dynamic conditions and uses the calculated probabilistic density function (PDF) The cumulative density function (CDF) is calculated to determine the degree of collision risk.

와 구간

에 대해서 확률 변수

가 구간에 포함될 확률

는

가 된다.Generally, probability density function (PDF) is a function that shows the distribution of random variables, and the integral value of the function over a certain interval becomes a probability value that the random variable value is included in the interval. That is, the probability density function

And section

For a random variable

Probability to be included in the interval

The

.

의 누적분포함수는

가 된다. 확률 변수의 종류가 확실할 경우에는 아래 부분 첨자를 생략해

와 같이 표기하기도 한다.The cumulative distribution function (CDF), for a certain probability distribution, represents the probability that a random variable is less than or equal to a certain value. Expressed as an equation, a random variable

The cumulative distribution function of

. If the type of the random variable is certain, omit the subscripts below.

And so on.

The electronic control unit 20 calculates a TTC and a DTC for each model, and calculates a probability density function (PDF) and a cumulative distribution function (CDF) using the calculated TTC and DTC.

For example, first, a first model, which is a constant acceleration model, is applied to calculate TTC1 and DTC1, and PDF1 and CDF1 are calculated using the calculated TTC1 and DTC1. The first collision risk is determined based on the calculated PDF1 and CDF1.

For example, if the calculated PDF1 is greater than PDF1_ref and the calculated CDF1 is greater than CDF1_ref, the first collision risk is large. If PDF1 is less than PDF1_ref and CDF1 is less than CDF1_ref, it is determined that the first collision risk is small.

Then, TTC2 and DTC2 are calculated by applying the second model, which is a constant speed model, and PDF2 and CDF2 are calculated using the calculated TTC2 and DTC2. The second collision risk is determined based on the calculated PDF2 and CDF2.

For example, if the calculated PDF2 is greater than PDF2_ref and the calculated CDF2 is greater than CDF2_ref, then the second collision risk is large. If PDF2 is less than PDF2_ref and CDF2 is less than CDF2_ref,

Finally, TTC3 and DTC3 are calculated by applying a third model, which is a non-sound acceleration model, and PDF3 and CDF3 are calculated using the calculated TTC3 and DTC3. The third collision risk is determined based on the calculated PDF3 and CDF3.

For example, if the calculated PDF3 is larger than PDF3_ref and the calculated CDF3 is larger than CDF3_ref, the third collision risk is large. If PDF3 is smaller than PDF3_ref and CDF3 is smaller than CDF3_ref, it is determined that the third collision risk is small. At this time, PDF1_ref to PDF3_ref and CDF1_ref to CDF3_ref can be changed by the driver.

Finally, the electronic control unit 20 determines the final collision risk by synthesizing the determined first collision risk, the second collision risk, and the third collision risk.

On the other hand, the electronic control unit 20 determines the risk of collision with the preceding vehicle based on the determined final collision risk by using a visible warning, an audible warning, a haptic warning, And determines that the driver is aware of the danger, and changes the alarm combination and alarm amount accordingly.

The electronic control unit 20 determines that the absolute value of the differential value of the vehicle speed sensed by the vehicle speed sensor is less than the absolute value of the acceleration value sensed by the acceleration sensor and the brake pedal pressure exceeds the reference pressure, If the yaw rate sensed by the driver exceeds the reference yaw rate, it is determined that the driver has recognized the danger. Here, the reference yaw rate may be an absolute value of a value obtained by multiplying the differential value of the steering angle sensed by the steering angle sensor by the vehicle speed sensed by the vehicle speed sensor divided by the vehicle length.

When it is determined that the driver recognizes the risk of collision, the electronic control unit 20 changes the alarm combination and the alarm amount accordingly. For example, a Stage 1 warning is a video alert, a more dangerous two-stage warning is a video warning and an audio warning together, and a three-stage warning, which is more dangerous than a Stage 2 warning, If the warning is to be performed together, the electronic control unit 20 alerts the driver to perceive the risk of collision by performing a warning according to each danger level, and while the warning is being executed, the driver recognizes the danger, If the vehicle operation is detected according to the driver's risk, the warning combination and alarm amount are changed according to the changed risk level.

A control method of the vehicle collision avoidance apparatus having the above-described configuration will be described.

First, the electronic control unit 20 calculates the distance (distance) between the vehicle and the preceding vehicle using the front sensor 11 such as a radar or a camera installed in front of the vehicle, And a relative speed and a relative acceleration with respect to each other (110). At this time, the electronic control unit 20 controls the vehicle speed, the vehicle acceleration, the steering angle, the yaw rate sensor 15, and the lateral acceleration sensor 16 based on the vehicle speed sensor 12, the acceleration sensor 13, the steering angle sensor 14, Yaw rate, and lateral acceleration, respectively.

After detecting the sensor information, the electronic control unit 20 receives the various sensor information and determines the collision risk according to various dynamic conditions with the preceding vehicle (120). At this time, the electronic control unit 20 calculates TTC1 and DTC1 with respect to the first model, which is a constant acceleration model, and calculates PDF1 and CDF1 using the calculated TTC1 and DTC1, and based on the calculated PDF1 and CDF1 Thereby determining the first collision risk.

In addition, with respect to the second model, which is a constant speed model, TTC2 and DTC2 are calculated, and PDF2 and CDF2 are calculated using the calculated TTC2 and DTC2. Based on the calculated PDF2 and CDF2, .

Also, with respect to the third model as the non-sound acceleration model, TTC3 and DTC3 are calculated, and PDF3 and CDF3 are calculated using the calculated TTC3 and DTC3, and the third collision risk is calculated based on the calculated PDF3 and CDF3 .

The electronic control unit 20 then determines 130 the final collision risk by summing the determined first collision risk, the second collision risk, and the third collision risk.

After determining the final collision risk, the electronic control unit 20 warns the driver of the risk of collision with the preceding vehicle based on the determined final collision risk using a video warning, an audio warning, a vibration warning, or the like (140).

The electronic control unit 20 then determines (150) whether or not it is a driver's risk of collision involving vehicle operation to reduce the risk of collision in accordance with the warning of the operating mode 140. At this time, the electronic control unit 20 determines that the absolute value of the differential value of the vehicle speed sensed by the vehicle speed sensor 12 is less than the absolute value of the acceleration value sensed by the acceleration sensor 13, If the pressure is exceeded and the yaw rate sensed by the yaw rate sensor exceeds the reference yaw rate, it is determined that the driver is aware of the danger.

When it is determined that the driver recognizes the risk of collision, the electronic control unit 20 changes the alarm combination and the alarm amount accordingly (160). If a vehicle operation is detected based on the driver's risk, such as reducing the speed of the vehicle by recognizing the danger while the driver is performing the warning, change the combination of the warning and the amount of alarm according to the changed risk level.

11: Front sensor 12: Vehicle speed sensor
13: Acceleration sensor 14: Steering angle sensor
15: yaw rate sensor 16: lateral acceleration sensor
17: Accelerator pedal sensor 18: Brake pedal sensor
20: Electronic control unit 30: Brake part
40: Warning section

Claims (8)

A front sensing sensor for sensing a distance to the front vehicle, a relative speed, and a relative acceleration;
A warning unit for warning of a risk of collision with the preceding vehicle;
And a controller for receiving sensor information input from the front sensing sensor and determining collision risk for each model from vehicle speed models representing a plurality of dynamic situations between the vehicle and the preceding vehicle, And an electronic control unit for determining a collision risk and warning a risk of collision with the preceding vehicle based on the determined final collision risk,
The vehicle speed model may be a constant acceleration model in which the vehicle is assumed to travel at a constant acceleration, a constant speed model in which the vehicle is assumed to travel at a constant speed, or a negative value in which the vehicle is assumed to travel at a non- ≪ / RTI > including at least two of the non-acceleration models,
The electronic control unit calculates the collision predicted time (TTC) and the collision predicted distance (DTC) for each model, calculates the collision risk for each model using the calculated collision predicted time (TTC) and the estimated collision distance (DTC) Respectively. The method according to claim 1,
The electronic control unit calculates the probability density function (PDF) and the cumulative distribution function (CDF) using the collision prediction time (TTC) and the collision prediction distance (DTC) (PDF) and a cumulative distribution function (CDF), respectively. The method according to claim 1,
The electronic control unit performs a warning made up of a combination of a video warning, an audio warning, and a vibration warning in accordance with the determined final collision risk, and performs a vehicle operation for reducing the risk of collision according to the warning during the warning And changing the warning combination if it is determined that the driver recognizes the risk of collision as a result of the determination. The method of claim 3,
A plurality of vehicle sensors for sensing a vehicle speed, an acceleration, a steering angle, a yaw rate, a lateral acceleration and a brake pedal pressure of the vehicle,
Wherein the electronic control unit determines that the absolute value of the differential value of the vehicle speed sensed by the plurality of vehicle sensors is less than the absolute value of the sensed acceleration and that the sensed brake pedal pressure exceeds the reference pressure, And determines that the driver recognizes the risk of collision if the rate exceeds the reference yaw rate.
The reference yaw rate is an absolute value of a value obtained by multiplying the differential value of the sensed steering angle by the sensed vehicle speed divided by the vehicle length. The sensor information inputted from the front sensor for sensing the distance to the front vehicle, the relative speed and the relative acceleration,
Determining collision risk for each model from the vehicle speed models representing a plurality of dynamic situations of the vehicle and the preceding vehicle,
Determining a final collision risk based on the determined collision risk,
A risk of collision with the preceding vehicle is warned based on the determined final collision risk,
The vehicle speed model may be a constant acceleration model in which the vehicle is assumed to travel at a constant acceleration, a constant speed model in which the vehicle is assumed to travel at a constant speed, or a negative value in which the vehicle is assumed to travel at a non- ≪ / RTI > including at least two of the non-acceleration models,
The collision risk estimating method according to any one of claims 1 to 5, wherein the collision risk estimating unit calculates collision expected time (TTC) and collision expected distance (DTC) for each model, Wherein the collision risk is determined based on the collision risk. 6. The method of claim 5,
In order to determine the collision risk for each model, the probability density function (PDF) and the cumulative distribution function (CDF) are calculated using the collision prediction time (TTC) and the collision prediction distance (DTC) ,
(PDF) and a cumulative distribution function (CDF), respectively, based on the calculated probability density function (PDF) and the cumulative distribution function (CDF), respectively. 6. The method of claim 5,
An alarm of a combination of a video warning, an audio warning, and a vibration warning in accordance with the determined final collision risk, and a driver's collision involving a vehicle operation for reducing the risk of collision according to the warning during the warning And changing the warning combination if it is determined that the driver has recognized the risk of collision. 8. The method of claim 7,
Wherein an absolute value of a differential value of a vehicle speed sensed by a plurality of vehicle sensors for sensing a vehicle speed, an acceleration, a steering angle, a yaw rate, a lateral acceleration and a brake pedal pressure of the vehicle is less than an absolute value of the sensed acceleration, And determining that the driver is aware of the risk of collision if the sensed brake pedal pressure exceeds a reference pressure and the sensed yaw rate exceeds a reference yaw rate.
The reference yaw rate is an absolute value of a value obtained by multiplying the differential value of the sensed steering angle by the sensed vehicle speed divided by the vehicle length.

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