DE102014217846A1 - Method for carrying out a lane change by a driver assistance system of a motor vehicle - Google Patents

Abstract

The invention relates to a method for carrying out a lane change by a driver assistance system (5) of a motor vehicle (3), on a target lane (9) located objects (19) are detected, wherein a number of speeds of the target lane (9) detected objects (9) 19) is determined, depending on the or each determined speed for the lane change from an exit lane (7) on the Zielfahrspur (9) required target speed of the motor vehicle (3) is determined, depending on the determined target speed, a distance adjustment between the Motor vehicle (3) and located on the Ausgangsfahrspur (7) located in front of the motor vehicle (3) object (17), and wherein only after the distance adjustment, an automatic lane change by the driver assistance system (5) is initiated. Furthermore, the invention relates to a driver assistance system (5), by means of which a corresponding method can be carried out.

Description

The invention relates to a method for carrying out a lane change by a driver assistance system of a motor vehicle.

A driver assistance system is now standard in a modern motor vehicle. The aim of such a driver assistance system is to increase road safety by the precautionary avoidance of dangerous situations that can lead to accidents. Other goals are to increase comfort by relieving the driver, as well as to facilitate the orientation by situationally prepared and driver-friendly conveyed environment information.

A driver assistance system can partially autonomously or autonomously intervene in the drive, the control or in signaling devices of the motor vehicle, warn the driver shortly before or during a critical situation or prevent this by an independent intervention. Here, a driver assistance system is designed so that the responsibility remains with the driver, so this can override autonomous interventions.

Driver assistance systems are constantly being developed, their individual functions linked together or additional functions implemented to automate vehicle guidance. In addition to those with automatic object recognition or with an automatic brake function, conventional systems also include, in particular, driver assistance systems with automatic longitudinal and lateral control of a vehicle. The driver assistance systems with a longitudinal control function include, for example, such systems with an automatic distance and cruise control (Adaptive Cruise Control, ACC). Such driver assistance systems maintain a desired speed specified by the driver and, by means of automatic braking or acceleration, make it possible to automatically maintain the required safety distance to other road users even in changing traffic conditions.

Driver assistance systems with a lateral control function include, for example, so-called lane change assistants, which are now standard equipment for highly automated and high-priced vehicles. Lane change assistants detect vehicles approaching on a neighboring lane or target lane by means of an appropriate sensor system and warn a driver of imminent collisions when changing lanes. In the known systems, it is provided that a predetermined warning signal is generated during an intended lane change when a faster vehicle is located in the side or rear area of the own vehicle.

Also driver assistance systems are to be used, which allow an autonomous lane change. For this purpose, the vehicle environment is monitored accordingly and automatically initiated when detecting a traffic gap on a target lane of the lane change by the driver assistance system.

The problem with an autonomous lane change, however, is that the lane change performing vehicle in an unfavorable case on the target lane driving vehicles "brakes". For example, if a vehicle is traveling in a convoy on a lane with slow traffic and wants to change to a lane with faster traffic, the speed of the vehicle must be adjusted accordingly to the speed on the destination lane. If the vehicle follows a vehicle in front of it only with the required safety distance, as is the case, for example, in a system with an automatic distance and speed control, the vehicle can adapt its speed only after the lane change has taken place. This leads to an undesirable impairment of the traffic flow on the target lane.

The invention is as a first object to provide a method which allows a lane change without affecting the flow of traffic while maintaining the predetermined safety distance to other road users.

As a second object of the invention is to provide a driver assistance system, which allows a corresponding lane change.

The first object of the invention is achieved according to the invention by a method for carrying out a lane change by a driver assistance system of a motor vehicle, wherein objects located on a target lane are detected, wherein the speeds of the objects detected on the destination lane are determined, depending on the or each detected Speed is determined for the lane change from a starting lane to the target lane target speed of the motor vehicle is determined, depending on the determined target speed, a distance adjustment between the motor vehicle and located on the exit lane in front of the motor vehicle object, and wherein only after the distance adjustment an automatic Lane change is initiated by the driver assistance system.

The starting point for the finding of a solution is the consideration that a vehicle should already drive ahead of a desired lane change with the speed prevailing on the destination lane in order to avoid an undesired impairment of the traffic flow on a corresponding destination lane. However, this is only possible if a vehicle traveling on an exit lane, driving a lane change, drives with a sufficiently large distance to an object located in front of it. The vehicle can then accelerate on the exit lane and make the lane change at the desired speed.

On the other hand, for example, in dense traffic on a highway or at rush hour, the situation arises that a vehicle that changes from a starting lane with slower traffic - on a highway, for example, from a column with slow heavy traffic - to a destination lane with faster traffic, not sufficient Has space to accelerate. Usually then the vehicle changes the lane at its current speed and can accelerate only after the lane change on the target lane. An impairment of the traffic flowing on the target lane traffic is thus not preventable or is accepted.

Alternatively, it could deliberately be undershot the existing to a front vehicle distance to the acceleration, but this can only be done in a targeted intervention of the driver in vehicles that use a driver assistance system with a distance and speed control, for example, by temporarily overriding the control function or off , As a result, in addition to the potential traffic hazard by falling below a safety distance and the ride comfort for the driver is reduced.

Taking into account the above considerations, the invention recognizes that a lane change in compliance with the necessary safety distances and without affecting other road users is possible if before the initiation of lane change so on the exit lane - the distance between the lane change performing vehicle and one in front of this Object is adapted to the traffic flow on the destination lane.

By making such a distance adjustment, a vehicle that wants to make a lane change, already on the exit lane accelerate before it on the adjacent driving stiffeners, so the target lane threading. The same applies to the change of a vehicle into a small gap of a slower moving traffic column. Again, a lane change is initiated only after the distance adjustment.

By way of example, a common traffic situation on highways can be considered in which a vehicle wants to overtake a truck. In order not to interfere with vehicles driving on the target lane and force them to brake suddenly, the vehicle first increases its distance to the preceding truck. After reaching the system preset distance, the vehicle can accelerate and then safely change the lane with the speed adapted to the traffic flow on the destination lane. The safety distance to the truck is permanently maintained, so that maximum safety is given.

An alternative traffic situation represents the lane change in a slow column. For example, if a vehicle wants to leave a highway and is currently in the left lane (exit lane), it must thread itself into the slower traffic on the right lane (destination lane). Instead of initiating a lane change with the current speed and to endanger possibly slower moving vehicles on the target lane by sharp braking or the minimum distance to a vehicle on the target lane can not comply, the vehicle can its speed - increasing the distance to a front of him Vehicle and then change the lane at a target speed adjusted to the slow column speed.

The detection of objects located on the destination lane and the determination of the corresponding speeds of the objects detected on the destination lane are preferably carried out by means of an on-vehicle surroundings sensor system, such as, for example, by means of radar, LIDAR (Light Detection And Ranging). By means of the environmental sensor system, the area around the vehicle which is to carry out the lane change is monitored and the data expediently evaluated in an evaluation unit of the driver assistance system. The driver assistance system is then on the basis of the recorded and evaluated data in a position to initiate a lane change automatically and perform.

In particular, the respective absolute speeds or relative speeds of the detected objects can be determined as speeds, and also average speeds of the objects can be calculated from the respectively detected individual speeds. These speeds flow in particular into the determination of a velocity profile characterizing the traffic flow on the destination lane. In addition will be To determine such a speed profile, the distances between the objects located on the destination lane are also taken into account. For further processing and use of the corresponding data or values, preferably suitable algorithms stored in the driver assistance system are used.

As objects, both on the destination lane and on the exit lane, in the present case all road users are understood to be considered during a lane change. In addition to classic passenger cars and trucks, these include construction machines or agricultural machines, as well as cyclists and pedestrians. Of course, the objects include unexpected obstacles such as lane blockages, broken down vehicles or lane closures in the form of traffic signs, etc.

In order to achieve a corresponding distance adaptation, the minimum distance a _min required for lane change is expediently determined as a function of the target speed of the motor vehicle to an object located in front of the motor vehicle. The actual distance between the vehicle and the object located in front of it is expediently increased to the corresponding minimum distance a _min . An increase in distance is in this case achieved by reducing the speed of the vehicle, for which purpose actively braked by means of the driver assistance system or alternatively only gas can no longer be given.

Advantageously, the vehicle is accelerated after the distance adjustment on the exit lane to the target speed. Due to the distance to the object located in front of the vehicle, ie the minimum distance a _min , the speed required for unimpaired lane change can be achieved without falling below the predetermined safety distance. When changing from a lane with fast flowing traffic to a target lane with slow-flowing traffic may be waived if necessary, an acceleration when the vehicle is already driven by the reduced due to the increase in distance airspeed with the desired target speed.

Preferably, the lane change after reaching the target speed, ie after the initiation of the change, also automatically - by the accordingly established for this purpose driver assistance system - carried out. In this case, the vehicle preferably changes the lane in compliance with the safety distance to an object located in front of it, as well as to the objects located on the destination lane.

For a lane change is even possible, suitable traffic gaps are detected on the target lane for the lane change. For this purpose, the driver assistance system detects the vehicle environment and recognizes the traffic gaps that are suitable for a lane change at the current speed and the distance - both to the preceding vehicle and on the target lane driving vehicle. Likewise, the acceleration capacity of the vehicle and the target speed are taken into account.

In a further advantageous embodiment, the speed of the motor vehicle is reduced when falling below a predetermined safety _distance a _sec between the motor vehicle and an object located on the exit lane in front of the motor vehicle. Thus, for example, in the event that despite an increase in distance and before the lane change an obstacle on the exit lane slows down the local traffic and the safety distance is exceeded, an already started acceleration process be aborted. The speed of the vehicle is reduced accordingly and the lane change is not performed.

If no objects on the target lane are detected or detected by means of the driver assistance system, the target lane is thus free, then the motor vehicle expediently changes at the same speed from the starting lane to the destination lane. The same applies analogously to a well-traveled target lane, but in which the traffic gaps are so great that an acceleration is still possible on the target lane itself, ie after the lane change has already taken place.

The second object of the invention is achieved by a driver assistance system for a motor vehicle for carrying out a lane change, comprising an environment sensor system for detecting the vehicle environment, an evaluation unit for evaluating the data determined by means of environment sensor data, and an execution unit, wherein the execution unit for initiating an automatic lane change of the type described above and is designed.

The driver assistance system or the execution unit is preferably able to determine the target speed and to automatically adjust the distance of the vehicle driving a lane change to an object located in front of it. At a sufficient distance a _min , the vehicle is advantageously accelerated by means of the driver assistance system and the lane change after reaching the target speed automatically initiated and possibly also advantageously carried out.

Further preferred embodiments for the driver assistance system result from the subclaims directed to the method. In this case, the advantages named for the method and its variants can be transferred analogously to the driver assistance system.

In the following, embodiments of the invention will be explained in more detail with reference to a drawing. Showing:

1 to 5 the successive steps of a lane change in a traffic situation in dense traffic on the destination lane, as well as

6 a block diagram illustrating some of different possible traffic scenarios.

In 1 is a traffic situation 1 shown in the a motor vehicle 3 with the help of a built-in driver assistance system 5 from an exit lane 7 on a target lane 9 wants to change. The driver assistance system 5 In this case, an environment sensor system is included 11 for detecting the vehicle environment, an evaluation unit 13 for evaluation by means of environment sensors 11 determined data, as well as an execution unit 15 to initiate and carry out an automatic lane change.

In the traffic situation shown here 1 the traffic flows on the destination lane 9 faster than the traffic on the exit lane 7 , The respective speeds are indicated by the arrows on the road users, with a short arrow indicating a low speed and a long arrow indicating a high speed.

The car 3 moves at a specified speed with the safety _distance a _sec behind an object 17 , in this case a truck. The driver assistance system 5 of the motor vehicle 3 detected by means of environment sensors 11 the traffic flow on the destination lane 9 , Based on the speeds of the target lane 9 located objects 19 , Passenger cars in the present case, the target speed of the motor vehicle 3 determined before the lane change. At the same time by means of environment sensors 13 missing links 21 recorded and a sufficient for a lane change traffic gap 23 selected.

After determining the target speed, the necessary distance a _min to that in front of the vehicle by means of a suitable algorithm 3 driving truck 11 determined. The distance to the truck 11 is by reducing the speed of the motor vehicle 3 adjusted accordingly. The distance between the motor vehicle 3 and the truck 11 is increased in this case until it is large enough to then accelerate to the desired target speed on the output lane 7 to enable ( 2 ).

The acceleration process itself is in 3 shown. Here is the desired minimum distance a _min reached and the vehicle 3 increases its speed until reaching the target speed. Only when the target speed is reached is the lane change by the driver assistance system 5 initiated ( 4 ).

The car 3 then threads itself in the on the target lane 9 moving traffic ( 5 ). The entire lane change happens while maintaining the safety _distance a _sec between the truck 11 and the motor vehicle 3 and at the same time without affecting traffic flowing on the destination lane.

In 6 is a blockdiagram 31 shown, by means of which various traffic situations can be reconstructed. At the beginning, it is checked whether there is traffic on the lane in front of the lane change car (step 33 ). If this is not the case, the journey continues without a lane change.

If there is traffic in front of the vehicle and a lane change is desired, then it is checked whether traffic is also on the neighboring lane (step 35 ). In the case of a free destination lane, the driver assistance system can immediately make a lane change (step 37 ).

When a destination lane is traveled, a corresponding traffic lane is searched for on the lane (step 39 ) and the remaining time until the lane change of the vehicle from the exit lane into the detected traffic gap is calculated (step 41 ). Then, the necessary distance for a lane change a _min to the vehicle in front is calculated (step 43 ) and the current distance a _is compared (step 45 ). If the current distance a _is greater than the necessary distance a _min , the one lane change, that is to say the acceleration to the target speed and the subsequent threading into the traffic lane on the destination lane, can be carried out (step 37 ).

If the distance a _is less than the distance a _min , then the distance is increased accordingly (step 47 ). Then the speeds of the objects located on the destination lane or the corresponding speed profile are determined (step 49 ) and, depending thereon, determines the target speed required for the lane change (step 51 ).

Subsequently, the necessary distance for a lane change a _min to the preceding vehicle is calculated (step 43 ) and the current distance a _is compared (step 45 ). If the current distance a _is the necessary distance a _min , the lane change is performed (step 37 ).

Of course, in addition to the steps shown here, further or alternative steps or a different sequence of steps are possible.

LIST OF REFERENCE NUMBERS

1

traffic situation

3

motor vehicle

5

Driver assistance system

7

output lane

9

target lane

11

environment sensors

13

evaluation

15

execution unit

17

object

19

object

21

transport gap

23

transport gap

31

block diagram

33

step

35

step

37

step

39

step

41

step

43

step

45

step

47

step

49

step

51

step

Claims (8)

Method for carrying out a lane change by a driver assistance system ( 5 ) of a motor vehicle ( 3 ), wherein on a target lane ( 9 ) ( 19 ), wherein a number of speeds of the on the target lane ( 9 ) detected objects ( 19 ), wherein, depending on the or each determined speed, one for the lane change from an exit lane ( 7 ) to the destination lane ( 9 ) required target speed of the motor vehicle ( 3 ), wherein, depending on the determined target speed, a distance adjustment between the motor vehicle ( 3 ) and one on the exit lane ( 7 ) in front of the motor vehicle ( 3 ) ( 17 ), and wherein only after the distance adjustment an automatic lane change by the driver assistance system ( 5 ) is initiated. Method according to claim 1, wherein, based on the target speed of the motor vehicle ( 3 ) a required for lane change minimum distance a _min to one in front of the motor vehicle ( 3 ) ( 17 ) is determined. Method according to claim 1 or 2, wherein the motor vehicle ( 3 ) after the distance has been adjusted on the exit lane ( 7 ) is accelerated to the target speed.  Method according to one of the preceding claims, wherein the lane change is performed automatically after reaching the target speed. Method according to one of the preceding claims, wherein on the target lane ( 9 ) suitable for the lane change traffic gaps ( 21 . 23 ). Method according to one of the preceding claims, wherein when falling below a predetermined safety _distance a _sec between the motor vehicle ( 3 ) and one on the exit lane ( 7 ) in front of the motor vehicle ( 3 ) ( 17 ) the speed of the motor vehicle ( 3 ) is reduced. Method according to one of the preceding claims, wherein the motor vehicle ( 3 ) with free destination lane ( 9 ) at a constant speed from the exit lane ( 7 ) to the destination lane ( 9 ) changes. Driver assistance system ( 5 ) for a motor vehicle ( 3 ) for carrying out a lane change, comprising an environment sensor system ( 11 ) for detecting the vehicle environment, an evaluation unit ( 13 ) for evaluation by means of environment sensors ( 11 ), and an execution unit ( 15 ), the execution unit ( 15 ) is set up and designed to initiate an automatic lane change according to a method having the features according to one of the preceding claims.

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