KR20150129950A - Method for unfolding external air bag - Google Patents

Abstract

Introduced is an unfolding method of an external air bag, comprising: a setting step of setting a detection area of a front side; and a target selecting step of selecting a target product by comparing the relative velocity of a detection production within the detection area or overlap or TTE which is the time until the collision with an air bag cushion in the assumption of the unfolding of the external air bag, and comparing the TTE with a predetermined reference time. The reference time is changed according to the velocity of the vehicle or the relative velocity of the detection product and the vehicle or the overlap. The unfolding method of the external air bag comprises: a stability determination step of determining wherein a vehicle is in a stable state or unstable state through the comparison of a predicted yaw rate and a measured yaw rate of the vehicle; a prediction step of determining whether a predicted relative velocity and the overlap are more than or equal to a certain level or not when the collision of the target product and the vehicle is assumed; and an unfolding step of unfolding the external air bag if the vehicle is in the stable state and the predicted relative velocity and the overlap of the target product is higher than or equal to the certain level.

Description

{METHOD FOR UNFOLDING EXTERNAL AIR BAG}

The present invention relates to a method of deploying an external airbag for mounting an external airbag to a vehicle at an accurate timing based on prediction of an effective collision mounted on a vehicle.

Particularly, after judging a certain degree of deployment, after judging both the traction stability of the vehicle and the probability of collision with the opponent vehicle and the possibility of collision and avoidance, the external airbag is finally deployed and the malfunction The present invention relates to a method for expanding an external air bag that can increase the reliability of the system by significantly reducing the possibility.

BACKGROUND ART [0002] In recent years, an external air bag developed from the front or rear of a vehicle toward the outside has been developed and proposed as a technique for further enhancing the safety of a vehicle.

This basically means that the collision of the vehicle is detected and predicted in advance to develop the airbag, and the airbag is deployed at the correct timing to obtain the maximum impact absorption effect. When the airbag is deployed, it is deployed properly and the stability of the system should be high. There is a problem in that the reliability of the system must be increased by preventing the mistaken development of the morning.

Conventional KR 10-2012-0013799 A "Control method of an airbag module utilizing pre-collision information" includes a first step of detecting information on an object located on the vehicle front side through an ultrasonic sensor of a vehicle and a radar sensor of a vehicle; A second step of comparing information on the distance to the object among the information on the object detected by the ultrasonic sensor and information on the distance to the object among information on the same object detected by the radar sensor, Information on an object detected by the ultrasonic sensor and information on the same object detected by the radar sensor according to the comparison result of the object and information on the same object detected by the radar sensor, A third step of judging whether or not the object is located in a region where the object can collide with the vehicle, And to present a first one way control of the module "utilizing collision version information comprises the step 4 to deploy the air bag modules installed in the interior of the vehicle based on.

However, even with the above-described control method, there is no detailed control method for preventing the morning opening and obtaining a valid development of accurate collision determination, and even if the measurement performance of the sensor is insufficient, The data management method that can be used for data management is not presented.

Finally, there is a problem in that it is not possible to suggest a logic that can reliably prevent the morning dog by checking again the certainty of the deployment.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as an admission that the prior art is known to those skilled in the art.

KR 10-2012-0013799 A

It is an object of the present invention to provide an external airbag deployment method for installing an external airbag on a vehicle at a precise timing without any error based on prediction of an effective collision mounted on a vehicle.

According to another aspect of the present invention, there is provided an external air bag deployment method comprising: setting a detection area in front of a vehicle; The TTE is compared with a predetermined reference time and compared with a reference time, which is a remaining time until the airbag cushion collides with the airbag cushion, Wherein the time is varied according to the speed of the vehicle or the relative speed or overlap of the object and the vehicle; A stability determination step of determining whether the vehicle is in a stable or unstable state through comparison between a predicted yaw rate of the vehicle and a measured yaw rate; A prediction step of determining whether an overlap between the target object and the target relative speed at the time of collision between the target object and the vehicle is equal to or greater than a predetermined level; And a deploying step of deploying the external airbag when the vehicle is in a stable state and the overlap with the predicted relative speed of the object is equal to or higher than a certain level.

In the target selection step, when the TTE with the detected object is less than the reference time, the detected object can be selected as the target object.

The reference time can be increased as the speed of the vehicle or the relative speed of the detected object and the vehicle is increased.

The reference time can be reduced as the overlap between the detected object and the vehicle is smaller.

The reference time can be determined by a data map in which a first factor constituted by the speed of the vehicle or the relative speed of the object to be detected and the vehicle speed, and a second factor constituted by an overlap of the detected object and the vehicle are inputted and the reference time is output.

The object selecting step may be selected as the object when the relative velocity of the detected object is equal to or greater than the first reference, the overlap is equal to or greater than the second reference, and the TTE is equal to or less than the third reference, and the third reference may be the reference time.

The predetermined level of the prediction step and the development step may be a first criterion for the relative speed and a second criterion for the overlap.

The first criterion may be selected in a range of 40 to 50 km / h.

The second criterion may be selected in a range of 10 to 30%.

The third criterion may be selected in a range of 60 to 100 ms.

Wherein the estimating step further includes a probability step of determining whether the degree of change of the collision probability and the collision probability using the inverse number of the TTC, which is the remaining time until collision with the vehicle at the time of collision with the vehicle, is equal to or greater than a certain level, The external airbag can be deployed when the vehicle is in a stable state, the predicted relative speed of the object is overlapped with a predetermined level or higher, and the collision probability and collision probability are at or above a certain level.

The avoiding step may further include calculating a steering avoidance required distance and a braking avoiding necessary distance according to a relative speed with respect to the target object and comparing the distance with the target object with the required steering avoiding distance and the braking avoiding necessary distance , The deploying step may deploy the external airbag if the vehicle is in a stable state, the predicted relative speed of the object is at least a predetermined level, and the distance to the object is less than the required steering avoidance distance and braking avoidance required distance have.

The present invention relates to a method for expanding an external airbag, the method comprising: setting a detection range of a certain range; detecting a relative speed of the detected object in the detection area or an overlap or an expansion of the external airbag until collision with the airbag cushion The TTE is compared with a predetermined reference time, and the reference time varies depending on the speed of the vehicle or the relative speed or overlap of the detected object and the vehicle, and the estimated yaw rate of the vehicle And determines whether the vehicle is in a stable or unstable state by comparing the measured yaw rate and determines whether the overlap and the relative speed predicted at the time of collision between the object and the vehicle are equal to or more than a certain level. The external air bag can be deployed when the overlap and the predicted relative speed of the air bag are equal to or more than a predetermined level.

According to the method for expanding the external air bag having the above structure, it is difficult to avoid the obstacle with the preceding vehicle as the vehicle speed or the relative speed increases in selecting the target vehicle among the detected objects, and it is difficult It is possible to reduce the data amount of calculation and prevent the airbag from being opened in the morning.

In addition, after determining a certain degree of deployment, the traction stability of the vehicle, the physical quantity at the time of anticipation of collision with the opponent vehicle, and the probability of collision and avoidance are both determined, and finally, the external airbag is deployed to determine the malfunction By significantly reducing the possibility, the reliability of the system can be increased.

In addition, a precise control method can be presented that can prevent mornings and obtain valid deployments with accurate collision determination. In addition, a data management method is suggested that can make the most effective judgment even if the measurement performance of the sensor is insufficient.

And finally, by checking again the certainty of the deployment, we can suggest logic that can certainly prevent morning dogs.

1 is a flowchart of an external air bag deployment method according to an embodiment of the present invention;
2 to 3 are diagrams for explaining a detection area of an external air bag deployment method according to an embodiment of the present invention.
4 is a diagram for explaining a prediction process of an external air bag deployment method according to an embodiment of the present invention.
5 is a view for explaining an overlap determination of an external air bag deployment method according to an embodiment of the present invention;
6 to 7 are views for explaining TTC and TTE of the method for expanding an external air bag according to an embodiment of the present invention.
FIG. 8 is a diagram for explaining stabilization determination steps of an external air bag deployment method according to an embodiment of the present invention; FIG.
9 to 10 are diagrams for explaining the prediction step of the external air bag deployment method according to the embodiment of the present invention.
11 to 13 are diagrams for explaining an avoidance step of an external air bag deployment method according to an embodiment of the present invention.

Hereinafter, a method for deploying an external air bag according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a flowchart of an external air bag deployment method according to an embodiment of the present invention.

An external air bag deployment method of the present invention includes: a setting step of setting a detection area in front of a vehicle; The TTE is compared with a predetermined reference time and compared with a reference time, which is a remaining time until the airbag cushion collides with the airbag cushion, Wherein the time is varied according to the speed of the vehicle or the relative speed or overlap of the object and the vehicle; A stability determination step of determining whether the vehicle is in a stable or unstable state through comparison between a predicted yaw rate of the vehicle and a measured yaw rate; A prediction step of determining whether an overlap between the target object and the target relative speed at the time of collision between the target object and the vehicle is equal to or greater than a predetermined level; And a deploying step of deploying the external airbag when the vehicle is in a stable state and the overlap with the predicted relative speed of the object is equal to or higher than a certain level.

In particular, after the airbag is finally deployed, after the airbag has been judged to some degree, the traction stability of the vehicle, the physical quantity at the time of collision with the opponent vehicle and the probability of collision and avoidance are both determined, It is important to suggest a method of expanding the external air bag that can increase the reliability of the system by significantly reducing the possibility of malfunction.

An overall deployment embodiment including a method of deploying an external air bag of the present invention will be described together.

First, information of a self vehicle is obtained and information of a partner vehicle is obtained (S110, S120). Such information uses a sensor for measuring the physical quantity of the vehicle, and in the case of the relative object, the sensor is used for the laser, the radar, and the camera provided in the vehicle.

Specifically, the information of the vehicle obtained by these sensors is as follows.

On the other hand, information of a relative object obtained by the sensor is as follows.

Through the information of the sensors, relative information and absolute information between the object and the vehicle can be obtained in the vehicle. This information is used in the following process.

And a setting step (S130) of setting a detection area in front of the vehicle. In the setting step, as shown in FIG. 2, a real area is set in consideration of time and vehicle speed of the basic airbag moving and curved right and left along the steering of the vehicle and the external airbag of the vehicle.

Here, in the case of the basic region, the turning radius of the vehicle is obtained through the vehicle width and the steering angle, and the turning radius is obtained by offsetting the turning radius to the positive side of the vehicle. The turning radius of such a vehicle can be derived from the following equation.

In addition, the fan-shaped real area can be set in consideration of the relative speed of the vehicle and the deployment time of the external air bag.

That is, if the time at which the external airbag is full is 65 ms, the limit of the realistic area is obtained considering the time when the cushion is full at the minimum relative speed. That is, if it is desired to deploy and protect the external airbag from a collision of at least 44 km / h through the external airbag of the present invention at a relative speed of at least 44 km / h, And the thickness of the airbag is added to the thickness of the airbag, the limit value of the real area which should be minimized can be obtained.

In other words, the minimum value of the real area in this case is 1.5 m, which is the sum of the airbag thickness of 0.7 m + 65 ms and the distance of 44 km / h, which is 0.8 m, to obtain the minimum value of the real area.

In the case of the maximum value, when expanding the external airbag only up to a collision of a relative speed of up to 160 km / h, the maximum value is 2.9 m, which is a distance of 160 km / h by 0.7 m + 65 ms The minimum value of the real area can be obtained.

However, in this case, if the vehicle speed is very fast, it is possible to obtain a minimum recognition time for recognizing a sensor such as a camera, a time for the sensor to sample the measured value, and a time corresponding to the sampling frequency. Therefore, in the case of the maximum value, 8.9 m, which is a distance of 160 km / h by 200 ms, and 8.9 m, which is a distance of 160 km / h by 200 ms, which is a sampling time of 5 ms, The maximum value is 21.4m.

Therefore, in the case of the embodiment, the airbag can be explored by searching for a relative object from an area of at least 1.5 m toward the front of the vehicle, and the airbag can be deployed by searching for a relative object up to a maximum of 21.4 m.

In the case where both the basic area and the real area are overlapped with each other, the relative object is detected. In the case where the basic area and the detection area exist in both the basic area and the detection area, If 12 objects are detected, it can be used as a criterion that can be erased in the direction of eliminating the relative object in the region where the basic region and the real region do not overlap with each other.

On the other hand, if an object is found in the detection area, it is referred to as a detection object (S140). The physical quantity of the detected object is measured by a laser sensor or a radar sensor, and the type of the detected object can be determined through a camera sensor. Then, IDs are assigned to each of the detected objects, so that the relative physical quantities are sensed and continuously updated.

That is, the setting step may further include an update step (S220) of recognizing the detected object in the detection area, giving an ID (S210), and updating the detected object each time the forward sensor is measured.

On the other hand, the measurement period of the sensor is different for each sensor, but it is not easy to obtain the measurement period as necessary for the present invention. That is, FIG. 4 is a diagram for explaining a prediction process of the external air bag deployment method according to an embodiment of the present invention, in which the object selection step and the prediction step update the data of the detected object and the object at every measurement period of the forward sensor The predictive data is calculated at predetermined time intervals during the measurement period, and the predictive data can be used as the data of the detected object and the object.

That is, if the measurement period of the sensor is 80 ms, data is not provided for 80 ms between them. Therefore, in such a case, it is basically necessary to update the measured value every 80 ms, which is a measurement period, but it is also necessary to be able to predict the update value every 1 ms in the time between them.

For this purpose, if the sensor is measured at time i, as shown in the figure, the value at time i + 1 is obtained. This can be obtained using well-known tracking filters such as alpha-beta filters or Kalman filters. Then, in the time from i + 1 to i + 79, each value is updated. This process can be understood by the following formula.

As described above, the next position is obtained through the previous position and speed, and the next speed is used to continuously estimate the next speed with the present acceleration at the time of sensor measurement. Since it is already a very short time, the range of the error is not very large even if the following speeds are cumulatively calculated with the current acceleration. In the case of the TTE, the TTE time can be obtained by subtracting the airbag thickness of 0.7 m from the relative distance at each time, i.e., 1 ms, divided by the speed.

A risk selection step (S310) of selecting an object having the shortest TTE, which is the time remaining until the collision with the airbag cushion, assumes a dangerous object (1st collision anticipated vehicle) during deployment of the external air bag among the detected objects in the detection area; . Alternatively, in the risk selection step, an object having the shortest TTC, which is the remaining time until the vehicle collides with the vehicle, may be selected as a dangerous object.

That is, the object with the shortest TTE or TTC among the detected objects in the detection area is first selected as the dangerous object.

6 to 7 are views for explaining TTC and TTE of the method for expanding an external airbag according to an embodiment of the present invention, wherein TTE refers to the time remaining until the collision with the airbag cushion when the external airbag is deployed, Refers to the time remaining until the vehicle collides with a vehicle assuming a collision with the vehicle.

That is, assuming that the airbag is deployed as shown in FIG. 6, it refers to a time at which the marine object collides with the airbag at the time when the airbag is full. In this case, as shown in FIG. 7, the pressure of the cushion is increased with time according to the deployment of the airbag, thereby achieving the maximum at the time of full bloom and decreasing thereafter. . Therefore, in the case of the external airbag, the maximum shock absorption performance can be obtained when the TTE is obtained from the distance of the current relative object and the airbag is deployed at the same time as the obtained TTE.

On the other hand, the term TTC refers to the time until an object collides with a bumper of a vehicle, which is a concept frequently used in the concept of a conventional general built-in airbag.

Therefore, it is possible to select an object with the shortest TTC, which is the time remaining until collision with the vehicle, in the detection range of the detected vehicle, assuming a collision with the vehicle among the plurality of detected objects, The object with the shortest TTE or TTC among the detected objects is first selected as the dangerous object.

Then, as will be described below, the dangerous object is intensively examined and the deployment of the airbag is determined. That is, when the relative speed of the dangerous object is equal to or greater than the first reference value (S320), the overlap is equal to or greater than the second reference value (S330), and the TTE is equal to or less than the third reference value (S340) . In addition, it is also possible to search all the detected objects without selecting a dangerous object, and to directly detect the target object among the detected objects.

First, the relative speed of the detected object is checked. The relative speed is preferably at least 44 km / h as the first criterion. This is because the relative speed at which the vehicle should be at least protected is 44 km / h.

In addition, it is preferable that the overlapping amount of the detected object is 20% or more as a second criterion. In the case of the overlap, as shown in Fig. 5, a side having a larger value among the left boundary of the vehicle and the right boundary of the opponent object is selected, and a value smaller than the right boundary of the vehicle and the left boundary of the object is selected, Is expressed as the distance of the overlap, the value is divided by the width of the car, and then multiplied by 100 and expressed as a percentage.

Therefore, if the object recognized as the detected object has a high relative speed and a large overlap, it is promoted to the object.

It is also possible to select a detected object as a target object when the TTE is below the third reference. This is because if the detected object has a large relative speed, a large overlap, and a short collision time, the risk of collision is high.

On the other hand, it is preferable that the TTE is compared with a reference time as a third reference prepared in advance, and the reference time is varied in accordance with the speed of the vehicle or the relative speed or overlap of the vehicle and the detected object.

That is, the reference time (third criterion) is derived from the data map shown in Table 4 below, and the TTE with the detected object is compared with the predetermined reference time.

As described above, when the TTE with the detected object is less than or equal to the reference time, the object selecting step can select the detected object as the object (S332). The reference time can be increased as the speed of the vehicle or the relative speed of the detected object and the vehicle is increased. In other words, if the relative speed is high, the probability of collision is high and the possibility of avoidance is shortened as quickly as possible. Therefore, even if the TTE is somewhat large, it should be selected as the object. Therefore, the reference time to be compared with the TTE is increased.

On the other hand, the reference time can be reduced as the overlap between the detected object and the vehicle becomes smaller. In other words, the smaller the overlap, the greater the likelihood of avoidance. The smaller the overlap, the more the TTE should be excluded from the object. Therefore, the reference time to be compared with the TTE decreases as the overlap becomes smaller.

As shown in Table 4, the reference time is inputted with a first factor composed of the speed of the vehicle or the relative speed of the detected object and the vehicle, a second factor composed of the overlap of the detected object and the vehicle, Can be determined by the map.

According to the method for expanding the external air bag, it is difficult to avoid the obstacle with the preceding vehicle as the vehicle speed or the relative speed increases in selecting the target vehicle among the detected objects. Considering that the larger the overlap is, Therefore, it is possible to reduce the data amount of operation and prevent the airbag from being opened in the morning.

On the other hand, thereafter, a stability determination step (S350) is performed to determine whether the vehicle is in a stable or unstable state by comparing the estimated yaw rate with the measured yaw rate.

That is, the vehicle is viewed as an object having two degrees of freedom and it is possible to see whether or not the stability of the vehicle can be maintained. In short, if the difference between the yaw rate of the actual vehicle and the predicted yaw rate exceeds a certain level, then the stability of the vehicle is lost. This is a part widely used in the conventional ESP, do.

FIG. 8 is a view for explaining a stability determination step of the method for deploying an external air bag according to an embodiment of the present invention. When the vehicle can travel while maintaining stability of traction, it is designated as FLAG 1, If you can go into a deployable situation and lose traction stability, do not deploy the external airbag by storing it as FLAG 0. Therefore, even if the driving of the vehicle is dangerous, the external airbag is deployed to prevent the elements that interfere with the driving in advance.

Further, thereafter, prediction steps S410, S420, S430, and S440 are performed to determine whether the overlap and the predicted relative speed at the time of collision of the vehicle are equal to or more than a predetermined level. A certain level of the prediction step and the development step may be a first criterion for the relative speed and a second criterion for the overlap.

9 to 10 are diagrams for explaining a prediction step of the external air bag deployment method according to an embodiment of the present invention. If the object and the vehicle are at the constant-velocity running state, the case where the conventional relative speed exceeds the first reference is still maintained You will be satisfied. However, if there is a decelerating situation, there may be a situation of 42km / h lower than 44km / h at the time of actual collision, and it is not necessary to deploy an external airbag until such time.

Therefore, even if the relative speed of the current object exceeds the minimum reference value of 44 km / h, if the predicted value at the collision point does not exceed 44 km / h, the airbag is not deployed. It can be seen that the average of the data of the relative speed over a certain period of time is obtained, the relative acceleration is obtained by dividing it by the time, and the relative speed is predicted and tracked at the TTC instant through the relative acceleration.

Similarly, in the case of the overlap, as shown in FIG. 10, it is predicted whether or not the actual collision will occur with an overlap of 20% or more by predicting the instantaneous overlap occurring in the TTC. Similarly, the average of the lateral relative velocities up to the present time is obtained, and the overlap can be predicted by tracking the lateral relative displacement at the TTC instant.

Thus, if the relative speed exceeds the current speed of 44 km / h and the current overlap exceeds 20%, then the external air bag is deployed if the relative speed predicted at the moment of collision does not exceed 44 km / h or the overlap does not exceed 20% By avoiding the morning dog is to prevent.

If the collision probability and the collision probability are equal to or greater than a predetermined level, the external airbag can be deployed (S510, S520). That is, the case of the dispatch probability (CP) can be defined as the following equation.

Therefore, if the collision probability is obtained by obtaining the TTC and the reciprocal of the TTC, or by multiplying the TTC by the amount of overlap, and if the collision probability exceeds a predetermined value, the probability of the actual collision is very high. prevent.

In addition, the collision probability may be calculated every 1 ms, and if the slope of the rate of change is less than a predetermined slope, the airbag may not be deployed to prevent morning opening.

On the other hand, when the distance between the vehicle and the target object is smaller than the required steering avoidance distance and the braking avoidance required distance, the external airbag can be deployed (S530, S540). 11 to 13 are diagrams for explaining the avoidance step of the method for deploying an external airbag according to an embodiment of the present invention. The vehicle may avoid an emergency collision by deceleration or steering, It can be expressed by the relationship between speed and relative distance.

Therefore, when the respective graphs relating to the relative speed, the steering avoidance required distance, and the braking avoidance required distance are superimposed and when the graph corresponds to the lower portion of the line in the graph of FIG. 13, braking or steering can be avoided Is not present. Therefore, by deploying the airbag only in this case, malfunction of the airbag can be conservatively prevented.

The necessary distance for braking avoidance can be expressed by the following equation.

This is a function that divides the square of the relative velocity by twice the gravitational acceleration g.

The required distance of the steering avoidance can be expressed by the following equation.

This is obtained by dividing twice the current overlap by the lateral relative acceleration, taking the square root, and then multiplying by the lateral relative velocity, which is the distance required for steering avoidance.

After the above process, finally, the confirmation step S560 of confirming the presence of the object via the ultrasonic sensor is performed to prevent the error of the sensor, and the communication and the normal state of the part are checked (S570) The airbag is deployed (S580).

The method of deploying the external airbag of the present invention can be summarized as follows. First, by setting the detection region in consideration of the deployment characteristics of the external airbag, only the substantial object data can be observed and the burden of data processing can be significantly reduced.

In addition, data can be generated in units of 1 ms by predictive calculation of data every measurement period of the sensor, so that it is possible to cope stably even in high-speed situations.

After first selecting the detection object based on TTC and TTE, the object is identified and continuously tracked according to the actual collision situation by upgrading to the object in consideration of relative speed, overlap and TTE.

In addition, even if the vehicle is promoted to the target object, the relative speed and the overlap at the time of the TTC can be seen to prevent amalgamation, and the collision probability, the change rate, the vehicle stability, the steering avoidance required distance, It is characterized by the fact that the worry of malfunctioning is very low.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the following claims It will be apparent to those of ordinary skill in the art.

S130: Setting step S220: Updating step
S310: Risk selection step S350: Stability determination step
S410, S420, S430, S440: prediction step S560: determination step

Claims (13)

A setting step of setting a detection area in front of the vehicle;
The target object is selected based on the relative speed of the detected object in the detection area or the time remaining until collision with the airbag cushion assumes the overlap or the expansion of the external airbag in the assumption. The TTE is compared with a preset reference time, Wherein the time is changed in accordance with the speed of the vehicle or the relative speed or overlap of the object and the vehicle;
A stability determination step of determining whether the vehicle is in a stable or unstable state through comparison between a predicted yaw rate of the vehicle and a measured yaw rate;
A prediction step of determining whether an overlap between the target object and the target relative speed at the time of collision between the target object and the vehicle is equal to or greater than a predetermined level; And
And a deployment step of deploying the external airbag when the vehicle is in a stable state and the overlap and the predicted relative speed of the object are equal to or higher than a certain level. The method according to claim 1,
Wherein the object selecting step selects the detected object as the object when the TTE with the detected object is equal to or less than the reference time. The method according to claim 1,
Wherein the reference time is increased as the speed of the vehicle or the relative speed of the detected object and the vehicle is increased. The method according to claim 1,
Wherein the reference time is reduced as the overlap between the detected object and the vehicle is smaller. The method according to claim 1,
The reference time is determined by a data map in which a first factor composed of the speed of the vehicle or the relative speed of the detected object and the vehicle and a second factor composed of the overlap of the detected object and the vehicle are input and the reference time is output. Of the airbag. The method according to claim 1,
Wherein the object selecting step selects the object as the object when the relative velocity of the object to be detected is equal to or greater than the first reference and the overlap is equal to or greater than the second reference and the TTE is equal to or less than the third reference, Way. The method of claim 6,
Wherein the predetermined level of the prediction step and the developing step is a first criterion for the relative speed and a second criterion for the overlap. The method of claim 6,
Wherein the first criterion is selected in a range of 40 to 50 km / h. The method of claim 6,
Wherein the second criterion is selected in a range of 10 to 30%. The method of claim 6,
Wherein the third criterion is selected in a range of 60 to 100 ms. The method according to claim 1,
Wherein the estimating step further comprises a probability step of determining whether the degree of change of the collision probability and the collision probability using the inverse number of TTC, which is the remaining time until collision with the vehicle,
Wherein the deploying step deploys the external airbag when the vehicle is in a stable state, the predicted relative speed of the object is overlapped with a predetermined level or higher, and the collision probability and collision probability are at or above a certain level. Way. The method according to claim 1,
The avoiding step may further include calculating a steering avoidance required distance and a braking avoiding necessary distance according to a relative speed with respect to the target object and comparing the distance with the target object with the required steering avoiding distance and the braking avoiding necessary distance ,
Wherein the deploying step deploys the external airbag when the vehicle is in a stable state, the predicted relative speed of the object is equal to or greater than a predetermined level, and the distance to the object is less than the required steering avoidance distance and braking avoidance required distance Of the airbag. A method for expanding an external airbag, the method comprising: setting a detection range of a certain range; detecting a relative speed of the detected object in the detection area or a time remaining until the collision with the airbag cushion occurs, The TTE is compared with a preset reference time, and the reference time is varied according to the speed of the vehicle or the relative speed or overlap of the detected object and the vehicle, and the estimated yaw rate of the vehicle and the measured yaw rate It is judged whether the vehicle is stable or unstable by comparing the yaw rate, and it is judged whether the overlap relative to the predicted relative speed at the time of collision between the object and the vehicle is equal to or more than a certain level. And when the relative speed and the overlap are equal to or more than a certain level, the external airbag is deployed.

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