KR102295578B1 - Control Method of Autonomous Vehicle - Google Patents

Abstract

The present invention provides a method comprising the steps of: 1. determining a need to overtake a preceding vehicle on a driving lane; 2. If it is determined that there is a need for overtaking, determining the degree of risk during overtaking; 3. Changing the lane to a passing lane when it is determined that the risk level is low during overtaking; 4. Increasing the acceleration of the own vehicle after changing the lane; 5. determining whether the host vehicle has overtaken the preceding vehicle; 6. determining whether to return to the driving lane; 7. determining whether to control the deceleration of the host vehicle; 8. determining the degree of risk when returning to the driving lane; and 9. performing a return to the driving lane when it is determined that the degree of risk is low when returning to the driving lane.

Description

Control method of overtaking of autonomous vehicle {Control Method of Autonomous Vehicle}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automobiles, and more particularly, to autonomous vehicles.

BACKGROUND ART In general, an autonomous vehicle refers to a vehicle that can drive to a destination by grasping a road and surrounding conditions by itself without a driver operating an accelerator pedal, a steering wheel, or a brake.

As a representative technology that enables autonomous driving, there is an adaptive cruise control system (ASCC), which is a type of an advanced driver assistance system (ADAS). When there is no preceding vehicle, the vehicle drives at a constant speed at the speed set by the driver, and when a preceding vehicle is recognized, it detects the speed and distance of the vehicle in front and controls the inter-vehicle distance by itself. In addition, it has a function of automatically stopping when the preceding vehicle stops, and automatically starting when the preceding vehicle starts.

For autonomous driving, technological advances such as high-performance cameras, lasers, and collision avoidance devices are required, and driving situation recognition/response control technology that comprehensively determines and processes driving situation information is essential.

On the other hand, if the autonomous vehicle encounters a slow-moving truck or passenger car in front of it while driving while maintaining its lane, it is necessary to overtake such a low-speed vehicle for smooth driving. Here, overtaking in a broad sense means changing to the left or right lane and returning to the original lane.

However, in many countries, the driving lane is on the right and the passing lane is on the left, and in most overtaking cases, it is common and desirable by law to change to the left lane to overtake low-speed vehicles and then return to the right lane.

An object of the present invention is to provide a method for controlling overtaking of an autonomous vehicle, such as determining the necessity of overtaking while driving in an autonomous vehicle, changing to a passing lane, returning to a driving lane, and changing a lane when necessary.

The present invention provides a method comprising the steps of: 1. determining a need to overtake a preceding vehicle on a driving lane; 2. If it is determined that there is a need for overtaking, determining the degree of risk during overtaking; 3. Changing the lane to a passing lane when it is determined that the risk level is low during overtaking; 4. Increasing the acceleration of the own vehicle after changing the lane; 5. determining whether the host vehicle has overtaken the preceding vehicle; 6. determining whether to return to the driving lane; 7. determining whether to control the deceleration of the host vehicle; 8. determining the degree of risk when returning to the driving lane; and 9. performing a return to the driving lane when it is determined that the degree of risk is low when returning to the driving lane.

The first step is (1) overtaking lane speed > first threshold value (own lane speed + first factor * speed limit) (2) inter-vehicle distance < second threshold value (3) own vehicle speed < third threshold value (second factor * speed limit) (4) relative speed with the preceding vehicle < fourth threshold value (5) dependency degree required acceleration value input to the controller < fifth threshold value, and determining the conditions, If all of them are satisfied, it may be determined that there is a need for overtaking, and if any one of the above conditions is not satisfied, it may be determined that there is no need for overtaking.

In step 1, the count value is measured for each condition, and if the count value continuously increases for a specific time, it is determined that overtaking is necessary, and if at least one of the count values is decreased, overtaking is not required can judge

The first step may further include determining the state of the vehicle.

The determining of the lane state may include: determining whether the total number of lanes is equal to or greater than two lanes; determining whether the host vehicle is driving in the first lane; Determining whether there is an exclusive bus lane for the overtaking lane and whether the overtaking is prohibited time; may include.

If the total number of lanes is not equal to or greater than two lanes, the current lane may be maintained, and if the total number of lanes is greater than or equal to two lanes, it may be determined whether the host vehicle is driving in the first lane.

If the total number of lanes is two or more and the vehicle is driving in one lane, it is possible to control the lane change to the right lane without overtaking.

If the overtaking lane is a bus-only lane and during no-overtaking time, the lane change can be controlled to the right.

Step 2 above is (1) the distance to the vehicle in front/rear of the changing lane > 6th threshold value (2) TTC with the vehicle in front/rear in the changing lane > 7th threshold (3) for the vehicle behind the changing lane Deceleration condition > eighth threshold value Determining the above conditions, if all of the above conditions are satisfied, it is determined that the overtaking risk is low, and if any one of the conditions is not satisfied, it is determined that the overtaking risk is high. can

In the second step, the count value is measured for each condition, and if the count value is continuously increased for a specific time, it is determined that the risk when overtaking is low, and if at least one of the count values is decreased, the risk when overtaking is can be considered high.

The second step may further include determining the degree of risk due to the rushing vehicle in anticipation of a case in which a vehicle close to the rear of the driving lane overtakes the own vehicle.

The step of determining the degree of risk due to the rushing vehicle may be predicted by grasping the amount of change in the lateral position of the rear vehicle for a unit time.

The first and second steps may include: collecting data for determining the conditions by sensing the vehicle and the surrounding environment; an overtaking determination step of determining a count through the collected data; determining whether the count is incremented; When the increased count value is greater than or equal to the threshold value, the vehicle may attempt to change to the overtaking lane, and if the count value is less than the threshold value, it may return to the overtaking determination step.

determining whether the count is maintained if the count does not increase;

If the count is not maintained, performing the overtaking determination again, and if the count is maintained, checking whether a time-out (Time Out); may further include.

In the step of examining whether the time-out occurs, if the time-out occurs, the count is initialized, and if the time-out is not reached, the overtaking determination may be continuously performed.

The method may further include determining whether to cancel the overtaking lane change by determining the overtaking risk while attempting to change to the overtaking lane.

When the overtaking lane change is canceled in the step of determining whether to cancel the overtaking lane change, the overtaking determination may be performed using the count value reduced from the threshold value by the margin value without initializing the count value.

Step 3 may include (1) turning on a left turn indicator, (2) controlling a left lane change, and (3) controlling an acceleration of the own vehicle.

If the second step is further determined while the third step is performed and the level of risk when overtaking is determined, the lane change may be canceled or withheld until the level of risk is lowered.

In step 4, the longitudinal acceleration of the own vehicle may be accelerated until it reaches a set maximum speed so as to overtake the preceding vehicle in the lane before overtaking.

In step 5, when the own vehicle does not overtake the preceding vehicle, acceleration of the own vehicle is continued, and when the own vehicle overtakes the preceding vehicle, step 6 may be performed.

In step 6, it may be determined whether the speed of the lane for the original road to be returned to and whether vehicles are densely packed.

In step 6 above, (1) when there is no vehicle in front of the original road (2) the vehicle speed ahead of the original road > 3rd factor * maximum speed (3) The vehicle speed in front of the original road > 4th factor * the speed of the lane before overtaking ; The conditions may be determined, and if at least one of the conditions is satisfied, it may be determined that a return to the original vehicle is possible.

In step 7, if it is determined that it is possible to intervene by satisfying the TTC and distance conditions with the vehicle in front/rear of the original lane, deceleration of the own vehicle may be performed.

In step 7, the vehicle decelerates until it reaches the same speed as the vehicle in front of the original lane, and when it is determined that the distance to the vehicle in front is equal to or greater than a threshold value, deceleration control may be performed.

In step 8, (1) distance from the vehicle in front/rear of the original lane > ninth threshold value (2) TTC with the vehicle in front/rear of the original lane > 10th threshold value (3) for the vehicle behind the original lane deceleration condition > eleventh threshold; and determining the conditions. When all of the conditions are satisfied, it is determined that the risk upon return is low, and when any one of the conditions is not satisfied, it can be determined that the risk upon return is high.

Step 9 may include (1) turning on a right turn indicator, (2) controlling a right lane change, and (3) controlling an acceleration of the host vehicle.

and a state definition for determining the steps 5 to 8, wherein the state is, [state = 1] a state in which the preceding vehicle on the original lane has not yet been overtaken after the overtaking lane change is completed; [ state = 2 ] The preceding vehicle is overtaken, but the speed of the original lane is still slow; [ state = 3 ] The speed of the original lane is faster than the previous vehicle overtaking by a certain amount, so it is good to return to the original lane. [ state = 4 ] The speed of the original lane is also faster than the speed before the overtaking, so it is a good state to return to the original lane. a condition in which an attempt is made to return to the driving lane; [ state = 5 ] As a result of risk determination, it is possible to immediately return to the original road; can be defined as

Step 5 determines [state = 1], Step 6 determines [state = 2] to [state = 4], and Step 7 is performed in [state = 4] and [state = 5], , step 8 determines [state = 5], and step 9 may be performed in [state = 4] and [state = 5].

Meanwhile, in the present invention, (1) overtaking lane speed > first threshold value (own lane speed + first factor * speed limit) (2) inter-vehicle distance < second threshold value (3) own vehicle speed < third threshold value (third 2 factor * speed limit) (4) relative speed with the preceding vehicle < fourth threshold value (5) required acceleration value input to dependency degree controller < fifth threshold value; Provide a method for controlling overtaking of an autonomous vehicle comprising determining the conditions, determining that overtaking is necessary when all of the conditions are satisfied, and determining that overtaking is not necessary if any one of the conditions is not satisfied do.

By measuring the count value for each of the above conditions, it is determined that overtaking is necessary when the count value continuously increases for a specific time, and when at least one of the count values decreases, it can be determined that overtaking is not required. .

On the other hand, the present invention comprises the steps of determining the need to overtake; and (1) the distance to the vehicle in front/rear of the changing lane > 6th threshold value (2) TTC with the vehicle in front/rear in the changing lane > 7th threshold (3) deceleration condition for the vehicle behind the changing lane > an eighth threshold; and determining the risk when overtaking by judging the conditions, wherein when all of the conditions are satisfied, it is determined that the risk when passing is low, and when any one of the conditions is not satisfied, the autonomy of determining that the risk when overtaking is high A method for controlling overtaking of a driving vehicle is provided.

By measuring the count value for each of the above conditions, if the count value continues to increase for a specific time, it is determined that the risk when overtaking is low, and if at least one of the count values is decreased, it can be determined that the risk when passing is high. have.

On the other hand, the present invention is the step of driving in the overtaking lane; and (1) when there is no vehicle in front of the original lane (2) the vehicle speed ahead of the original lane > 3rd factor * maximum speed (3) The vehicle speed in front of the original lane > 4th factor * the speed of the lane before overtaking; Provided is a method for controlling an autonomous vehicle overtaking, including determining a return to the original vehicle by determining the conditions, and determining that it is possible to return to the original vehicle from the overtaking lane when at least one of the above conditions is satisfied.

When it is determined that it is possible to return to the original vehicle, the method may further include a deceleration determination step of determining whether to decelerate the host vehicle.

In the step of determining whether to decelerate, the vehicle decelerates until it reaches the same speed as the vehicle in front of the original lane, and when it is determined that the distance to the vehicle in front is equal to or greater than a threshold value, deceleration control may be performed.

As described above, according to the invention of the overtaking control method of an autonomous driving vehicle of the present invention, the vehicle determines the need for overtaking by grasping the road condition and surrounding environment during autonomous driving, changing to the overtaking lane, returning to the driving lane, and changing lanes if necessary. You can have the control you need.

1 is a flowchart illustrating steps of a method for controlling overtaking of an autonomous vehicle according to an embodiment of the present invention.
2 is an exemplary diagram illustrating (a) overtaking in the left lane (b) changing the right lane when driving in the first lane (c) changing the right lane in the case of the left bus-only lane.
3 is a flowchart showing the steps of determining the overtaking necessity and the lane state according to the present embodiment.
4 shows data on the amount of lateral position change per unit time for determining overtaking of the own vehicle of the rear vehicle when overtaking in the present embodiment.
5 is a flowchart for overtaking judgment according to the present embodiment.
6 is an exemplary view showing a state in which (a) it is possible to return to the original vehicle without deceleration of the own vehicle (b) it is difficult to return to the original vehicle, so it is necessary to withhold the return or perform deceleration.
7 is an exemplary view showing the risk of lane change caused by a rushing vehicle (extreme driving vehicle).
8 shows an example of a state in which return to the original vehicle is possible through deceleration control in (a) (b) shows a speed-time graph of the host vehicle and the state vehicle.
9 is data illustrating a determination of whether to control deceleration and control of deceleration when returning to a driving lane.
10 is a view showing the flow by state for the return to the original vehicle of the present embodiment.

Hereinafter, the embodiments will become apparent through the accompanying drawings and description of the embodiments.

In the drawings, sizes are exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not fully reflect the actual size. Also, like reference numerals denote like elements throughout the description of the drawings.

1 is a flowchart showing the steps of a method for controlling overtaking of an autonomous vehicle according to an embodiment of the present invention, and FIG. 2 is (a) overtaking in the left lane (b) changing the right lane when driving in the first lane (c) the day of the left bus lane In this case, it is an exemplary diagram showing a right lane change, and FIG. 3 is a flowchart showing the steps of determining the overtaking necessity and the lane state according to the present embodiment.

The overtaking control method of the autonomous vehicle according to the present invention may be performed through the following steps as shown in FIG. 1 .

1. Determination of overtaking necessity (S100) 2. Determination of risk when overtaking (S200) 3. Lane change to overtaking lane (S300) 4. Longitudinal speed control (S400) 5. Determination of overtaking of preceding vehicle (S500) 6. Return Determination of original road speed (S600) 7. Deceleration control determination (S700) 8. Determination of risk when returning (S800) 9. Return to original road (S900)

1. Determination of overtaking necessity (S100)

For the determination of overtaking necessity, a determination criterion may be set according to the state of the autonomous vehicle (hereinafter referred to as the own vehicle) and the surrounding environment. As shown in (a) of FIG. 2, the driving of the own vehicle 10 is delayed due to the preceding vehicle (low-speed vehicle, 20) running at a speed too low compared to the maximum speed in front of the driving lane of the own vehicle 10 If it is judged that it is not smooth, it is necessary to overtake by changing the lane to the passing lane.

In this case, all of the following conditions must be satisfied. The following are conditions necessary for controlling for overtaking necessity.

The speed limit (Max Speed) to be described below may be a speed that the host vehicle can achieve as much as possible while driving on the road, or it may be a speed limit on the road in accordance with laws and regulations. Hereinafter, the lane speed (driving flow) may mean the speed of a target vehicle in a corresponding lane based on the own vehicle or an average value of the speed of target vehicles in the same lane of the rider's search range.

Condition (1): Overtaking lane speed > own lane speed + first factor ( factor1 ) * Max Speed (overtaking lane speed > 1st threshold)

{Own lane speed + first factor (factor1) * speed limit (Max Speed = first threshold)

In the above condition, when the first factor is 0.1 and the speed limit is 100Km/H (hereafter, Km/H is kph), there is no need to overtake only when the speed of the next lane (overtaking lane) is 10 kph or more faster than the speed of the own lane It can be judged that there is That is, a case where the driving flow of the lane (the left lane) to be overtaken is faster than the driving flow of the own lane (above the first threshold value) must be satisfied. For example, the first factor may be selected from any value less than one.

Condition (2): The preceding vehicle exists within a certain distance ( car gap distance < second threshold)

The above condition is also related to a criterion for stably determining an object by a lidar sensor in an autonomous vehicle. Therefore, the preceding vehicle and the host vehicle must exist within about 110 m, that is, within a range smaller than the second threshold value. If the distance between the vehicle and the preceding vehicle is too far, the probability that the lateral position information of the object on the lidar sensor will be inaccurate increases, and thus the possibility of erroneous judgment of the flow of the lane increases. For example, the second threshold may be set within 100 m to 200 m and may be modified.

Condition (3): own vehicle speed < second factor ( factor2 ) * Max Speed (Own vehicle speed < 3rd threshold)

{second factor (factor2) * limit speed (Max Speed) = third threshold value}

In the above conditions, when the second factor is 0.9 and the speed limit is 100 kph, if the host vehicle is traveling at 90 kph or higher, it is traveling close enough to the speed limit, so no matter how fast the speed in the next overtaking lane is, there is no need to overtake. judge That is, if the host vehicle is not running close to the speed limit and has a speed less than the third threshold, there is a need to overtake.

Condition (4): Relative speed with the preceding vehicle < 4th threshold

When the host vehicle is running at 80 kph and the preceding vehicle is running at 75 kph, if the fourth threshold value is +10 kph under the above condition, the relative speed does not exceed the fourth threshold value. Therefore, if the relative speed of the host vehicle is lower than the fourth threshold value at the present time, it is determined that acceleration is not possible in a situation where acceleration is possible, so that it is necessary to overtake. Here, the fourth threshold value may be modified.

Condition (5): Request input to the dependency controller acceleration value < 5th threshold

The above condition is that when driving on a road with a slope such as a hill, when the vehicle speed is slow compared to the input value, and when the required acceleration value input to the dependency controller is sufficiently given (higher than the fifth threshold value), overtaking may not Therefore, when the required acceleration value input to the dependency controller is lower than the fifth threshold value, there is a need to overtake.

When all of the above conditions (1) to (5) are satisfied, it can be determined that overtaking is necessary. Conversely, if any one of the above conditions is not satisfied, it may be determined that there is no need for overtaking.

As such, the method of determining the overtaking necessity when driving the autonomous vehicle can be controlled by setting a threshold value and a measurable count value for each item with respect to the above-described conditions (1) to (5). Therefore, the overtaking necessity is determined by measuring the count value for each item during driving, and if the measured count values are continuously increasing, overtaking is necessary, and if at least one of the count values is decreasing, overtaking is not required. It can be concluded that no

The above-described step ( S100 ) may further include the following lane state determination step for consideration for traffic regulations and the surrounding environment.

1-1. car condition judgment

In the lane state determination step, as shown in FIG. 3 , it is possible to determine the total number of lanes, how many lanes there are currently driving lanes, whether there is a bus-only lane on the left side, and whether or not there is an overtaking prohibition time.

First, it is determined whether the total number of lanes is two or more lanes (S110). If the total number of lanes is not more than 2 lanes, the current lane is maintained because driving is in the 1st lane. When the total number of lanes is greater than or equal to the second lane, it is determined whether the vehicle is currently driving in the primary lane (S120). In this case, if the vehicle is currently driving in the first lane, since the own vehicle is located in the first lane, which is the overtaking lane, it is not overtaken even if there is a need to overtake, and only the lane change to the right lane can be controlled.

If the own vehicle is not currently driving in the first lane, it is determined whether the left lane, which is a passing lane, is a bus-only lane (S130). At this time, overtaking may be performed in the left lane if it is not in the bus-only lane and during the overtaking prohibition time.

If it is a bus-only lane and it is time for overtaking, it is determined whether there is a lane on the right side (S140). If there is a lane on the right, you can only change lanes to the right without passing, and if there is no lane on the right, you can control to keep the lane.

2. Determination of risk when overtaking (S200)

When it is determined that there is a need for overtaking in the above-described step (S200), when it is determined that overtaking is necessary, the lane to the left (right lane when only changing lanes is performed) when overtaking is performed to prevent safety accidents and the like before overtaking. A risk assessment may be performed on the change.

Even in the above step, it is necessary to satisfy the following conditions.

(1) Distance from the vehicle in front/rear of the change lane > 6th threshold (distance condition)

When entering the overtaking lane (left side), it can be determined that the risk is low only when the respective distances between the vehicles in front and behind the vehicle entering the overtaking lane are equal to or greater than a certain sixth threshold value. If it is determined that the distance between the front and rear vehicles is closer than the sixth threshold value, it may be determined that overtaking is dangerous. For example, the sixth threshold may be selected from 100 m to 200 m and may be modified.

(2) with the vehicle in front/rear of the changing lane TTC > 7th threshold

TTC is the time to collision and can be calculated as a value obtained by dividing the distance between the vehicle in front and the vehicle behind in the overtaking lane by the relative speed. The information necessary for calculating the TTC may include a distance to the front/rear vehicle, a relative speed with respect to the front/rear vehicle, and the like. Accordingly, the TTC between the own vehicle and the vehicle in front of the overtaking lane and the TTC between the own vehicle and the vehicle behind the overtaking lane can be obtained.

Here, when the TTC is less than or equal to the seventh threshold, it may be determined that the risk of collision of the host vehicle with a vehicle in front or rear of the overtaking lane is high. Therefore, the risk is also lowered when the TTC is above the threshold. For example, the seventh threshold may be selected from 5 to 10 seconds, and may be modified.

(3) Conditions for decelerating the vehicle behind the change lane ( TTC while relative speed < 8th threshold)

The above condition is to determine whether it is possible to reach the same speed as the rear vehicle of the changing lane and the own vehicle within an allowance distance when the rear vehicle of the changing lane decelerates to an appropriate deceleration during the TTC for the rear vehicle of the changing lane.

In this case, when the own vehicle attempts to change lanes while turning on the left turn signal for lane change in the driving lane, the vehicle behind the change lane can recognize this and decelerate at a constant speed. As such, if the other vehicle (the vehicle behind the changing lane) decelerates so that the relative speed becomes less than or equal to the eighth threshold during TTC, it may be determined that the risk is low. However, the risk increases if the vehicle behind you in the changing lane is rushing fast.

In this way, the method for determining the risk during overtaking may set threshold values and measurable count values for each item with respect to the above-described conditions (1) to (3). Therefore, when the count value measured by measuring the count value while driving increases for each item, it is determined that the risk is low, and when at least one of the count values is less than the threshold value, the risk is determined to be high.

4 shows data on the amount of change in lateral position per unit time for determining overtaking of the own vehicle of the rear vehicle when overtaking in this embodiment, and FIG. 5 is a flowchart for determining overtaking according to this embodiment.

(4) roundabout Conditions for rear vehicles

The above condition is a condition of a special case that is different from the conditions described above in determining the degree of risk during overtaking, and is a condition for determining the level of risk for the driving lane, not the changed lane.

If it is judged that a vehicle close to the rear of the own vehicle on the original lane is passing the own vehicle, it is judged that there is a high risk of changing to the overtaking lane, so that the lane change may not be attempted or canceled. This can often occur especially when the own vehicle is following a slow vehicle, and the vehicle behind the driving lane also feels the need to pass due to the flow of the slow lane and tries to overtake in the overtaking lane.

The risk determination for the above condition may predict the overtaking of the own vehicle behind the own vehicle by grasping the amount of change in the lateral position of the rear vehicle for a unit time as shown in FIG. 4 . The above-described method may use a method of correcting the lateral position.

The above-described overtaking necessity determining step (S100) and overtaking risk determining step (S200) may have a series of flows as shown in FIG. 5 because overtaking is determined based on whether the count value is increased.

First, data for determining the conditions are collected by sensing the vehicle and the surrounding environment (S210). Count determination, that is, overtaking determination (S220) may be performed through the collected data. The overtaking determination may include overtaking, lane change, count increase/decrease/maintenance determination.

When the overtaking determination (S220) starts, it is determined whether the count increases for each item required for overtaking determination (S230). Here, if the count value does not increase, it is determined whether the count is maintained (S240). At this time, if the count is not maintained, the overtaking judgment is performed again (S220), and if the count is maintained, it is checked whether a time-out occurs, and when the time elapses, the Count is initialized to 0 (S260). If it is not timeout, the overtaking determination (S220) is continuously performed.

When the count value is increased in the above-described count increase determination step (S230), it is determined whether the count value is equal to or greater than a specific threshold value (S280). If the count value is less than the threshold value, the overtaking determination (S220) is continued, and if the count value is equal to or greater than the threshold value, the step (S300) of trying to change the lane to the overtaking lane is performed. As will be described later, if a risk occurs while attempting to change lanes, it may be further determined whether to cancel the overtaking lane change (S320).

If the overtaking lane change is canceled in step S320, the overtaking determination (S220) may be restarted with a value reduced by a certain margin from the threshold value without completely initializing the count value (S270).

3. Change the lane to the passing lane (S300)

When there is a need to overtake in the overtaking necessity step ( S100 ) and it is determined that the risk level is low in the overtaking risk determination system ( S200 ), the lane change step to the overtaking lane is performed ( S300 ).

Since the passing lane is made through the left lane, in this step, (1) turning on the left turn signal, (2) controlling the left lane change, and (3) controlling the acceleration of the own vehicle can be sequentially performed in this step. In other words, after turning on the left turn signal and expressing intention to overtake, the vehicle enters into the empty space of the left lane.

If the step of turning on the left turn signal and controlling the left lane change among these steps is performed, if it is determined that the risk when overtaking is high as described above, the lane change may be canceled or withheld until the risk is reduced.

4. longitudinal Speed control (S400)

After the lane change to the overtaking lane is completed through the above-described step S300, the control is performed to increase the longitudinal acceleration of the own vehicle enough to overtake the preceding vehicle in the lane before overtaking. For example, longitudinal speed control may allow acceleration to be achieved until a set maximum speed is reached.

5. Determination of overtaking of preceding vehicle (S500)

In this step, it is determined whether or not the own vehicle located in the overtaking lane has reached a position in which it passes the preceding vehicle in the driving lane before overtaking (passing) (S500). When the host vehicle does not overtake the preceding vehicle, acceleration of the host vehicle in the above-described step is continued, and when it is determined that the host vehicle has overtaken the preceding vehicle, a step of determining whether to return to the original driving lane is performed.

6 is an exemplary view showing (a) a state in which it is possible to return to the original vehicle without deceleration of the own vehicle (b) a state in which it is difficult to return to the original vehicle and there is a need to suspend the return or perform deceleration, and FIG. 7 is a rushing vehicle (excessive driving) It is an example diagram showing the risk of lane change by vehicle).

6. For the return one way Speed judgment (S600) [ one way Determination of whether to return]

In this step, the lane speed of the original lane is determined in order to return to the original driving lane. When overtaking, after changing the left lane and passing the preceding vehicle, the speed is faster than the original lane speed. In order to return to the original lane, it is necessary to determine the original lane speed and whether or not vehicles are concentrated on the original lane.

As shown in (a) of FIG. 6 , when the vehicle (vehicle A) in front of the original lane (traveling lane) to intervene is far away from the own vehicle 10 driving in the overtaking lane or the vehicle is not densely packed on the original lane In this case, it can be judged that it is possible to return to the original vehicle. In addition, it may not be necessary to perform deceleration of the host vehicle for return.

As shown in (b) of FIG. 6 , when the vehicle is somewhat dense on the original road (driving lane), it is difficult to return to the original vehicle, so the return to the original vehicle may be withheld or a certain amount of deceleration may be performed before returning to the original vehicle.

For control, the state is defined as follows, and it can be set to determine whether to return according to the state.

[ state = 1 ] A state in which the preceding vehicle on the original lane has not yet been overtaken after the completion of the left lane change during overtaking

[ state = 2 ] The preceding vehicle has passed, but the speed of the original lane (right front) is still slow

[ state = 3 ] A state in which it is good to return to the original lane because it beats the preceding vehicle and the speed on the original lane is also faster than before overtaking, but there is a high possibility of changing the right lane at the same time as the own vehicle because the vehicle rushing in the rear is close.

[ state = 4 ] The vehicle ahead is also overtaken, and the speed on the original lane is faster than before overtaking, so it is in a good state to return to the original lane. In addition, the vehicle is in a state in which it is necessary to attempt to return to the driving lane after a long time has passed since there is no vehicle rushing in the vicinity of the own vehicle or the vehicle has passed.

[ state = 5 ] As a result of the risk assessment, it is possible to return to the original road immediately.

According to the above-described state classification, the state in which a return to the original vehicle is possible is a case of [state = 3] to [state = 5].

The speed conditions for returning to the original vehicle are as follows.

(One) roundabout If there is no vehicle in front

(2) roundabout Forward speed > third factor ( factor3 ) * max speed ( MaxSpeed )

For example, when the forward speed of the original road is more than 90% of the maximum speed.

(3) roundabout Forward speed > 4th factor4 * before overtaking lane flow

For example, if the forward speed on the original lane is 5% or more faster than before overtaking.

When one or more of the above conditions are satisfied, it may be considered that the speed condition for returning to the original vehicle is satisfied.

Meanwhile, in addition to the above conditions, in order to return to the original lane, it is necessary to further determine an aggressive vehicle located in the overtaking lane. As shown in FIG. 7 , the rushing vehicle may be an example such as the vehicle B 20 showing an aggressive driving behavior behind the own vehicle 10 in the overtaking lane. When the vehicle 10 attempts to change the lane to the right lane (original lane), the rushing vehicle B 20 has a high probability of attempting a lane change while speeding together.

Therefore, since there is a risk of colliding with the rushing vehicle 20 at the moment when the host vehicle 10 returns to the original lane, if the rushing vehicle is detected, it is possible to command a return delay without attempting a lane change for safety.

In order to determine the rushing vehicle as described above, it is possible to determine whether the vehicle is a rushing vehicle from among the candidate groups by observing the longitudinal/lateral movement from the initial recognition of the rear-side radar. It is possible to check the rear approach of the vehicle that has rushed past the preceding vehicle and not decelerate. Also, in this case, as the state of [state = 3], even if it is determined that the degree of risk is low, the right turn indicator light for returning to the driving lane and deceleration may not be attempted.

When the rear-challenging vehicle changes lanes to the side, [state = 4] becomes [state = 4], and since the speed of the vehicle is completely far away and the degree of risk is lowered, a one-lane return command can be executed.

8 shows an example of a state in which return to the original vehicle is possible through deceleration control in (a) b) a speed-time graph of the host vehicle and the state vehicle, and FIG. It is data showing, and FIG. 10 is a view showing the flow by state for the return to the original vehicle in this embodiment.

7. Deceleration control determination (S700)

In this step, if the vehicle is decelerated to enter the dense original lane in consideration of the deceleration control amount in the above-described step (S600), only when it is calculated that it is possible to intervene by satisfying the TTC and distance conditions with the vehicles in front/rear of the original road Performs deceleration of own vehicle, otherwise deceleration is not performed.

If the vehicle decelerates unconditionally without determining whether to control the deceleration, a situation may occur in which it is impossible to return to the original vehicle despite the deceleration of the host vehicle. In this situation, if the deceleration and acceleration of the own vehicle are repeated, the traffic flow in the overtaking lane may be disturbed.

Therefore, when determining whether to control the deceleration, the distance to the vehicle A is the threshold value when the host vehicle 10 decelerates from the overtaking lane and becomes the same speed as the vehicle ahead (vehicle A) on the original lane as shown in FIG. If this is the case, it is determined that the vehicle can be cut into the original road through deceleration, and deceleration control is started.

When determining whether to control the deceleration, the speed-time graph may be predicted in advance as shown in FIG. When vehicle A assumes constant velocity motion, when the host vehicle 10 reaches the same speed as vehicle A, the relative distance (the area of the closed curve surrounded by the vehicle A speed and the own vehicle speed in the speed-time graph) can be calculated. can

The timing of determining whether to control the deceleration may vary depending on the relative speed with the vehicle B. That is, the greater the relative speed with the vehicle B, the greater the distance the vehicle is decelerated and additionally travels up to the same speed as the flow of the original road.

When the deceleration control is decided, the current maximum speed value is stored in the memory, and the maximum speed is temporarily changed to the speed of the vehicle ahead of the original road (vehicle A) to decelerate. After returning to the original vehicle, the maximum speed is returned to the original saved value.

During deceleration control, it was determined that it was possible to return to the original lane and the vehicle was decelerated, but if it is impossible to return to the original lane due to a change in the flow of the original lane or the entry of a new vehicle at the time immediately before entering the driving lane, the flow of the overtaking lane must not be disturbed. .

Therefore, after accelerating by raising the maximum speed up to the limit speed again, it is determined whether or not to control the deceleration again.

8. Determination of risk when returning (S800)

Determining the risk when returning (S800), as in step 2. Determining the risk when overtaking, before returning to the driving lane (original lane), changing the lane to the right (or left lane) when returning to prevent safety accidents, etc. risk assessment can be performed.

Even in the above step, it is necessary to satisfy the following conditions.

(1) Distance from the vehicle in front/rear of the return lane > ninth threshold

When entering the return lane (right), the distance between the front and rear vehicles that will be located in front of and behind the own vehicle entering the return lane must be greater than a certain threshold to determine that the risk is low. If it is determined that the distance between the front and rear vehicles is closer than the ninth threshold value, it may be determined that the return is dangerous.

(2) with the vehicle in front/rear of the return lane TTC > 10th threshold

TTC, Time to Collision may be calculated as a value obtained by dividing the distance between the vehicle in front and the vehicle in the rear of the return lane divided by the relative speed. The information necessary for calculating the TTC may include a distance to the front/rear vehicle, a relative speed with respect to the front/rear vehicle, and the like. Accordingly, it is possible to obtain the TTC between the own vehicle and the vehicle in front of the return lane and the TTC between the own vehicle and the vehicle behind the return lane.

Here, when the TTC is less than or equal to the threshold, it may be determined that there is a high risk that the host vehicle will collide with a vehicle in front or behind the return lane. Therefore, the risk is also lowered when the TTC is above the threshold.

(3) Relative vehicle deceleration condition < 11th threshold

The above condition is to determine whether it is possible to reach the same speed as the own vehicle within an allowance distance when decelerating to an appropriate deceleration during TTC. If there is a vehicle rapidly rushing from behind, the risk increases.

For example, if it is determined that a vehicle close to the rear of the own vehicle overtakes the own vehicle to the right, the lane change may not be attempted or canceled. Therefore, even in this case, it is possible to predict the overtaking of the own vehicle behind the own vehicle by grasping the amount of change in the lateral position of the rear vehicle for a unit time. The above-described method may use a method of correcting the lateral position.

As such, in the method of determining the risk upon return, a threshold value and a measurable count value may be set for each item with respect to the above-described conditions (1) to (3). Therefore, if the count values measured by measuring the count value during operation are equal to or greater than a certain threshold value for each item, the risk is determined to be low, and if at least one count value is less than the threshold value, the risk may be determined to be high.

9. Return to the driving lane (S900)

If it is determined in the above-described step (S800) that the degree of risk upon returning is low, the step of changing the lane to the original lane (driving lane) is performed (S900).

Since the return lane is made through the right lane, in this step, (1) turning on the right turn signal, (2) controlling the right lane change, and (3) controlling the acceleration of the own vehicle can be sequentially performed. That is, after turning on the right turn indicator to indicate intention to change lanes, the vehicle enters the empty space of the right lane.

In the step S900, as shown in FIG. 9, when the previous steps S700 and S800 return, the deceleration control is determined and the deceleration control is performed when necessary through the deceleration control, and when the deceleration is not required, the deceleration can be returned as it is. .

In the case of turning on the right turn signal and controlling the right lane change among these steps, if it is determined that the risk is high when returning, the lane change may be canceled or suspended until the risk is reduced.

On the other hand, a series of processes for returning to the original vehicle among the above-described steps will be supplementarily described for each state with reference to FIG. 10 .

First, in the state of [ state = 1 ], it is a state in which the preceding vehicle on the original lane has not yet been overtaken after the overtaking lane change is completed. Here, it is determined whether the preceding vehicle has passed ( S500 ). If the preceding vehicle has not passed, it is possible to check whether a time delay (Time Out) is present to return to the [state = 1] state or to determine the [state = 2] state.

In the [state = 2] state, it is determined whether the original road speed is satisfied in order to return to the original road because the preceding vehicle is overtaken but the original road speed is still low (S600). If the original road speed is not suitable for return, it is checked whether the time delay is It can move to step (S610).

If the speed is suitable for returning to the original vehicle in step 600, it is determined whether the vehicle rushing to the rear approaches (S610). Here, if the vehicle rushing to the rear approaches, it becomes [state = 3], and if the vehicle does not approach, it becomes [state = 4].

[ state = 3 ] by checking whether there is a time delay (Time Out), it is possible to return to the [ state = 2 ] state or to determine the [ state = 4 ] state.

In the [state = 4] state, the speed on the original lane is also faster than before the overtaking by overtaking the preceding vehicle, so it is a good state to return to the original road. The vehicle is in a state in which it is necessary to attempt to return to the driving lane after a long time has passed since there is no vehicle rushing in the vicinity of the own vehicle or the vehicle has passed. After [state = 4], it is determined whether deceleration control is required, appropriate deceleration control is performed when necessary, and the degree of risk is determined upon return (S800). Here, if there is no risk, it moves to the [ state = 5 ] state and returns immediately. If there is a risk, it switches to the [ state = 4 ] state and proceeds with the process for recovery while continuously checking the risk.

As described above, according to the invention of the overtaking control method of an autonomous driving vehicle of the present invention, the vehicle determines the need for overtaking by grasping the road condition and surrounding environment during autonomous driving, changing to the overtaking lane, returning to the driving lane, and changing lanes if necessary. You can have the control you need.

Features, structures, effects, etc. described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

10: own vehicle 20: preceding vehicle
S100: Determination of overtaking necessity S200: Determination of risk when overtaking
S300: Lane change to overtaking lane S400: Longitudinal speed control
S500: Determination of overtaking of the preceding vehicle S600: Determination of speed on the original road
S700: Deceleration control determination S800: Risk level determination upon return
S900 : Return to the original vehicle

Claims (21)

1. determining a need to overtake a preceding vehicle on the driving lane;
2. If it is determined that there is a need for overtaking, determining the degree of risk during overtaking;
3. Changing the lane to a passing lane when it is determined that the risk level is low during overtaking;
4. Increasing the acceleration of the own vehicle after changing the lane;
5. determining whether the host vehicle has overtaken the preceding vehicle;
6. determining whether to return to the driving lane;
7. determining whether to control the deceleration of the host vehicle;
8. determining the degree of risk when returning to the driving lane; and
9. When it is determined that the degree of risk is low when returning to the driving lane, performing a return to the driving lane;
The second step, the step of determining the degree of risk when overtaking,
(1) the distance from the vehicle in front/rear of the change lane > 6th threshold,
(2) TTC with the vehicle in front/rear of the changing lane > 7th threshold,
(3) the deceleration condition for the vehicle behind the change lane > the eighth threshold;
determining the conditions;
When all of the above conditions are satisfied, it is determined that the risk when overtaking is low, and when any one of the conditions is not satisfied, it is determined that the risk when passing is high,
The step of determining the degree of risk when overtaking,
The overtaking control method of an autonomous vehicle, further comprising the step of determining the degree of risk due to the predicted rushing vehicle by predicting the case where a vehicle close to the rear of the driving lane overtakes the own vehicle and grasping the amount of change in the lateral position of the rear vehicle for a unit time . According to claim 1,
Step 1 above
(1) Overtaking lane speed > first threshold (own lane speed + first factor * speed limit)
(2) inter-vehicle distance < second threshold
(3) Own vehicle speed < 3rd threshold (2nd factor * speed limit)
(4) relative speed with the preceding vehicle < fourth threshold
(5) Required acceleration value input to dependency controller < 5th threshold value
determining the conditions;
If all of the above conditions are satisfied, it is determined that overtaking is necessary,
An overtaking control method of an autonomous vehicle in which it is determined that there is no need to overtake if any one of the above conditions is not satisfied. 3. The method of claim 2,
In step 1, the count value is measured for each condition, and if the count value continuously increases for a specific time, it is determined that overtaking is necessary, and if at least one of the count values is decreased, overtaking is not required. The overtaking control method of self-driving vehicles that judges. 4. The method of claim 3,
The first step further comprises the step of determining the state of the vehicle,
The step of determining the state of the vehicle includes:
determining whether the total number of lanes is two or more lanes;
determining whether the host vehicle is driving in the first lane;
A method for controlling overtaking of an autonomous vehicle, comprising: determining whether there is a dedicated bus lane for the overtaking lane and whether overtaking is prohibited. 5. The method of claim 4,
If the total number of lanes is not more than two lanes, the current lane is maintained, and if the total number of lanes is greater than or equal to two lanes, it is determined whether the own vehicle is driving in the first lane,
If the total number of lanes is 2 or more and the vehicle is driving in 1 lane, it does not overtake and controls the lane change to the right lane.
An overtaking control method of an autonomous vehicle that controls a lane change to the right when the overtaking lane is a bus-only lane and no overtaking time. delete According to claim 1,
In the second step, the count value is measured for each condition, and if the count value is continuously increased for a specific time, it is determined that the risk when overtaking is low, and if at least one of the count values is decreased, the risk when overtaking is The overtaking control method of an autonomous vehicle that is judged to be high. delete 3. The method of claim 2,
Step 1 and Step 2 are
collecting data for determining the conditions by sensing the vehicle and the surrounding environment;
an overtaking determination step of determining a count through the collected data;
determining whether the count is incremented;
An overtaking control method of an autonomous vehicle that attempts to change to the overtaking lane when the increased count value is greater than or equal to the threshold value, and returns to the overtaking determination step when the count value is less than the threshold value. 10. The method of claim 9,
determining whether the count is maintained if the count does not increase;
If the count is not maintained, performing the overtaking determination again, and if the count is maintained, checking whether a time-out (Time Out); further comprising,
In the step of examining whether or not the time-out occurs, the overtaking control method of the autonomous vehicle in which the count is initialized when the time-out occurs, and the overtaking determination is continuously performed when the time-out is not reached. 11. The method of claim 10,
Further comprising the step of determining whether to cancel the overtaking lane change by judging the risk of overtaking while attempting to change to the overtaking lane,
In the step of determining whether to cancel the overtaking lane change
When canceling the overtaking lane change, the overtaking control method of an autonomous vehicle in which the overtaking judgment is performed using the count value reduced from the threshold value by the margin value without initializing the count value. 12. The method of claim 11,
Step 3 above
(1) Left turn indicator light on
(2) Left lane change control stage
(3) Acceleration control stage of own vehicle
A method for controlling overtaking of an autonomous vehicle comprising the above steps. 13. The method of claim 12,
When the second step is further determined during the third step and the level of risk when overtaking is determined, the overtaking control method of the autonomous driving vehicle cancels or withholds the lane change until the level of risk is lowered. 14. The method of claim 13,
In the fourth step, the overtaking control method of the autonomous vehicle is accelerating the longitudinal acceleration of the own vehicle until it reaches a set maximum speed so as to overtake the preceding vehicle in the lane before overtaking. 15. The method of claim 14,
In step 5, when the own vehicle does not overtake the preceding vehicle, acceleration of the own vehicle is continued, and when the own vehicle overtakes the preceding vehicle, step 6 is performed. 16. The method of claim 15,
Step 6 above
Condition (1) When there is no vehicle in front of the original lane
Condition (2) Forward vehicle speed on original lane > 3rd factor * Max speed
Condition (3) Speed of the vehicle ahead of the original lane > 4th factor * Speed of the lane before overtaking
An overtaking control method of an autonomous vehicle that determines the conditions, and determines that it is possible to return to the original vehicle when at least one of the conditions is satisfied. 17. The method of claim 16,
In step 7, if it is determined that it is possible to intervene by satisfying the TTC and distance conditions with the front/rear vehicle of the original road, the vehicle is decelerated, but the vehicle is decelerated until it reaches the same speed as the vehicle in front of the original road. An overtaking control method of an autonomous driving vehicle that performs deceleration control when it is determined that the distance to the vehicle is greater than or equal to a threshold value. 18. The method of claim 17,
Step 8 above
(1) Distance from the vehicle in front/rear of the original lane > 9th threshold
(2) TTC with the front/rear vehicle of the original lane > 10th threshold
(3) The deceleration condition for the vehicle behind the original lane > 11th threshold
determining the conditions;
If all of the above conditions are satisfied, it is determined that the risk of return is low,
An overtaking control method of an autonomous vehicle in which it is determined that a risk is high upon return if any one of the above conditions is not satisfied. 19. The method of claim 18,
Step 9 above
(1) Right turn indicator light on
(2) Right lane change control stage
(3) Acceleration control stage of own vehicle
A method for controlling overtaking of an autonomous vehicle comprising the above steps. delete delete

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