CN101124103A - Method for detecting an imminent overtaking process - Google Patents

Abstract

Method for identifying an imminent overtaking process, characterized by the following steps: -measuring the distance d to a vehicle travelling in front (26), -determining the relative speed of the vehicle travelling in front, -determining: whether or not an overtaking process is imminent is determined according to the value of a function f (d, v) that depends on d and v.

Description

A method for identifying the overtaking process faced

technical background

The invention relates to a method for recognizing an approaching overtaking maneuver.

Cars are increasingly being equipped with driver assistance systems which, by means of suitable sensor systems, for example by means of radar sensors, detect the surroundings of the own vehicle and support the driver while driving and/or warn against danger Condition. An example of such a driver assistance system is the so-called ACC (Adaptive Cruise Control) system, with which the speed of the car is adjusted to a desired speed selected by the driver and, if the car in front is at its own If the vehicle is in a lane, the distance to the vehicle driving ahead is measured by means of a radar sensor and automatically adjusted by adapting the vehicle's own speed. Such a system not only contributes to improving driving comfort, but also contributes to reducing the risk of accidents. If the driver wants to overtake a slower car in front, he can control the ACC system by manipulating the accelerator pedal and then enter the overtaking process by changing lanes.

When driving on motorways or multi-lane roads, lane changes, especially overtaking, however entail a high risk of accidents, for example if the driver incorrectly estimates the distance and/or speed of a vehicle approaching from behind in the overtaking lane, or Because the car is in a dead corner and thus ignored by the driver.

For this reason, driver assistance systems have been developed which support the driver during lane changes and/or output a warning signal if a safe lane change is not possible. Such systems, also known as lane change assistance systems, usually have an extended sensor system, such as a rear space radar for monitoring the vehicle wheels in the passing lane behind and/or a proximity radar Or ultrasonic sensors are used to monitor dead spots. If the system learns that the driver wants to perform a lane change, and if it is known from the sensor data that a safe lane change is not possible, a warning signal is output to the driver. Acceptance of such a system, however, depends on whether the driver's overtaking intentions can be known with sufficient reliability, since frequent false warnings greatly impair comfort and the feeling of safety.

Various methods are known for ascertaining the driver's overtaking intention.

For example, the methods described in DE 3500152A1, DE3622091A1 and DE29620357U1 are based on the evaluation of the state of the driving direction indicator. It can be considered that the driver makes aware of his intention to overtake by setting the direction indicator. However, the reliability of this method is limited, because on the one hand the setting of the direction indicator (of the left turn signal) does not always have to indicate that overtaking is required, on the other hand the possibility of the driver having to overtake has to be taken into account, and Before, the turn signals were not operated.

Driver assistance systems are also known which, as an additional sensor component, have a video system with which road signs can be detected and thus also the position of the vehicle relative to the left and right lane sides or the vehicle approaching them is known. a driveway side. A common application of assistance systems is to output a lane departure warning if the driver is not keeping the car close to the center of his own lane. Approaching the left lane boundary in such a system can also be understood as a sign of the driver's intention to overtake. However, the disadvantage is that the cost of the video sensor is relatively high, and such a sensor is relatively prone to failure, which leads to errors, especially in the case of poor visibility. Interpret and thus cause false alarms or the absence of warnings that are necessary in themselves.

DE 10118265 A1 describes a method in which the sideslip speed of the host vehicle is measured by means of a yaw sensor. Furthermore, the angular velocity of the preceding vehicle is measured by means of an angle-resolving positioning sensor, for example a radar sensor. By comparing these data, we can understand the situation of changing lanes. When driving at high speeds on motorways, however, the sideslip speeds that occur during slow lane changes are so low that sufficient measurement accuracy is often not achieved due to measurement noise and/or limited sensor resolution. Furthermore, in this method it can also happen that the intention to change lanes is judged incorrectly, or that an intention to change lanes that actually exists is not detected. An example is, for example, the situation in which the driver of the host vehicle changes lanes when entering a right-hand curve. In this case, although the angular velocities of the preceding vehicle are measured differently starting from zero, the corresponding sideslip of the own vehicle cannot be measured, because the driver does not follow the road and turns, but goes straight first, to change to the left side lane.

Contents of the invention

The method according to the invention having the features of the claims can be used reliably with relatively little sensor effort to detect an approaching overtaking process.

This method is based on an evaluation of the driver's behavior when approaching a slower moving car ahead. If the driver has no intention of overtaking, he reduces his speed when the distance to the car ahead is relatively large so that he does not drive too close to the car ahead. On the contrary, if he wants to overtake, he does not slow down, but sometimes even speeds up in order to merge into the traffic on the side lane. By comparing the measured distance to the target with the relative speed, the relative speed can be measured directly by means of a radar system or alternatively can be calculated from the time derivative of the measured distance, so that the driver can know before starting to change lanes To the driver's overtaking plan. A warning can be output to the driver if the vehicle is in a dead corner or if a vehicle is approaching at a high relative speed in the overtaking lane. Even in exceptional cases the driver's behavior is misinterpreted once and a warning is output, although the driver has no intention of overtaking, but the warning is not useless because it points out to the driver that he is getting too close to the car in front.

This method can recognize overtaking intentions even when the driver does not turn on the left turn signal. Conversely, if the driver has activated the turn signal for other reasons, it can be recognized that there is no attempt to overtake.

In the simplest case, only one distance-measuring sensor is required for carrying out the method, so that the method can be carried out even in motor vehicles which have only a very limited environment sensor. In particular, this method does not depend on the presence or absence of a video system, thereby also avoiding sources of interference due to the use of such a system. Correspondingly, it is also suitable for other sensor components already used in conventional methods, for example for measuring the yaw rate of the host vehicle, the angular velocity of the preceding vehicle, etc.

On the other hand, the method according to the invention can also be combined with the conventional method described above in order to achieve a higher recognition probability and reliability.

Advantageous refinements of the invention are specified in the dependent claims. A driver assistance system for carrying out the method is described in the independent product claim.

In a practical embodiment, the ratio v/d results from the relative speed V of the vehicle in front and the measured distance d to this vehicle.

This ratio or another suitable function of the parameters v and d (or v/d) (generally an increasing function for v and a decreasing function for d) constitutes a degree of probability that there is an overtaking attempt. If this probability is above a defined threshold value (this threshold value can also be changed according to the situation if necessary), then it is judged that the driver intends to change lanes, and if it is not possible to change lanes without risk, then Just output a warning.

The threshold value can depend, for example, on whether the driver activated a turn signal. Because turning on the turn signal itself just represents a sign that the driver intends to overtake, so it is appropriate to reduce the threshold, because only a small additional sign that there is an overtaking intention is needed, and other known signs can also be made in a similar manner. The result of the system used to identify lane-changing intentions affects the threshold value. On the other hand, the probability of overtaking intention obtained according to the parameters v and d and the probability obtained by other methods can be combined into a total probability, and then compared with the threshold Compare.

Description of drawings

An exemplary embodiment of the invention is shown in the drawings and described in detail in the following description. The accompanying drawings show:

Figure 1: A schematic diagram of a car with a driver assistance system drawn as a block diagram;

Figure 2: A diagram of a traffic situation for illustrating the method according to the invention;

Figures 3 to 5: Diagrams illustrating the principle of action of the method.

Detailed ways

FIG. 1 schematically shows a motor vehicle which is equipped with a driver assistance system which fulfills, for example, the function of an ACC system (Adaptive Speed Controller) and the function of a lane change assistant. An angle-resolving radar sensor 12 is provided as the sensor component, which is mounted in front of the vehicle and monitors the front area of the vehicle, and a rear space radar 14 is provided for monitoring the traffic situation behind on the passing lane, as well as An ultrasonic sensor 16 with which, in particular, vehicles in the passing lane can be detected, which are located in the blind spot between the interior rearview mirror, the exterior rearview mirror and the driver's field of view and also within the localization range of the radar sensors 12, 14 outside. The signals of these sensor components are analyzed and processed in an electronic control unit 18. If it has been recognized that the driver has an overtaking intention and is informed by these signals of the sensors 14, 16 that it is currently impossible to change lanes to the left side lane without danger, then A warning signal generator 20 , for example an acoustic signal transmitter, is activated via the control unit 18 for outputting a warning signal.

The precondition for this warning function is that the driver's intention to change lanes or overtake another vehicle can be fully and reliably known. The method detailed below is used for this.

FIG. 2 illustrates a typical traffic situation when a vehicle 10 equipped with a driver assistance system approaches a slower vehicle 26 ahead in the right lane 22 of a multi-lane highway 24 . The distance between motor vehicle 10 and 26 is measured by means of radar sensor 12 , as is the relative speed v of motor vehicle 26 relative to motor vehicle 10 . Based on the angular resolution of radar sensor 12 , it can also be seen that vehicle 26 is in right lane 22 , which is also driven by vehicle 10 .

The data processing system implemented in the control unit 18 must now know whether the driver of the motor vehicle 10 intends to overtake the motor vehicle 26 or whether he wants to reduce his speed in order to follow the motor vehicle 26 at a suitable distance. If the ACC system is active in this case, it automatically adapts the speed of motor vehicle 10 , but the driver can overshoot the system by actuating the accelerator pedal. This of course does not necessarily mean that the driver also really intends to overtake the car 26 .

The route that the driver of motor vehicle 10 intends to take is indicated by arrow 28 in FIG. 2 . The driver then intends to change into the left lane 30 in order to overtake the vehicle 26 .

FIG. 3 shows how the distance d varies as a function of the time t in the process. It may be assumed for simplicity that the cars 10 and 26 maintain their absolute velocities and therefore the relative velocity v is constant over time, as shown in FIG. 4 . The distance d thus decreases linearly with time.

In Fig. 5, the ordinate is the ratio v/d, and the abscissa is time t. This ratio is represented by a progressively increasing curve which exceeds a defined threshold value S at a certain instant t0.

Threshold S is selected (for example, according to empirical investigations), so that there is still a larger probability until time t0 for general car drivers: the driver does not want to overtake, but also reduces his speed in order to follow the car 26, On the other hand, after exceeding the threshold value S, it can be concluded at time t0 that the driver intends to carry out an overtaking process. Based on such a simple criterion, it is thus possible to detect the driver's intention to overtake, so that a warning signal may be output by means of the warning signal transmitter 20 .

Instead of the ratio v/d, another suitable parameter can also be used for the threshold value, which parameter is a function of the relative speed v and the distance d. Such a function should be such that it increases with increasing v and decreasing d, if the driver's willingness to overtake is to be detected on the basis of exceeding a threshold value S.

If the judging criterion consists in falling below a suitable threshold value, the mathematical equivalent is to consider a function which decreases with increasing v and decreasing d, for example a function of the ratio d/v.

According to a development, it is also possible to consider a function which also depends on the positive or negative acceleration of vehicle 10 .

The ratio v/d used here can be interpreted in a physical sense as the time it takes until the collision with vehicle 26 if both vehicles 10 , 26 continue to travel at an unchanged speed.

Claims (6)

1. discern the method for the overtaking process that is faced, it is characterized in that following steps:

-measure in front the automobile (26) of travelling apart from d,

The relative velocity v of-automobile in front of determining to travel and

-(d, value v) judges whether be faced with overtaking process according to the function f that depends on d and v.

2. by the described method of claim 1, it is characterized in that, if (d v) surpasses the threshold value of predesignating (S) to function f, judges to face overtaking process.

3. by the described method of claim 2, it is characterized in that described function f is the monotone increasing function of ratio v/d.

4. by the described method of claim 3, it is characterized in that described function f and ratio v/d are proportional.

5. by described method one of in the claim 2 to 4, it is characterized in that described threshold value (S) changes according to different situations.

6. the driver assistance system that is used for automobile (10), sensor (12) with at least one measuring distance is used to detect peripheral traffic conditions and has control unit (18) and is used to implement additional function, it is characterized in that, design described control unit (18) and be used for implementing by the described method of one of claim 1 to 5.

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