DE102009007254A1 - Method of controlling a lane keeping assistant and lane departure warning - Google Patents

Abstract

The invention relates to a lane departure warning assistant and a method for controlling a lane departure warning system in a vehicle (10), the method comprising the following steps: a) determining an actual position (14) and a desired driving line (16) of the vehicle (10); b) determining a transverse deviation (Δr) of the vehicle (10) taking into account the actual position (14) and the desired driving line (16); c) activating the lane departure warning as soon as the lateral deviation (Δr) exceeds a predefined threshold (Δr); and d) deactivating the lane departure warning device before the actual position (14) of the vehicle (10) reaches the desired driving line (16).

Description

The The invention relates to a method for controlling a lane departure warning system in a vehicle as well as a lane departure warning.

In The automotive industry has been known for quite some time Lane departure warning systems that reduce the risk of accidents and improve road safety overall.

For example, conventional lane departure warning systems known in the art calculate a lane keeping assistance torque in response to a lateral deviation of the vehicle from a desired driving line. A video camera measures the lateral offset of the vehicle to the ideal target driving line in a predefined distance. In the case of carelessness of the driver, the vehicle deviates from the desired driving line, so that the transverse deviation increases. As soon as the lateral deviation exceeds a predetermined threshold, the lane departure warning is activated. This then provides a lane keeping assistance torque, an asymmetric braking force, or other suitable means for influencing the direction of travel to reduce the lateral deviation again. Upon reaching the ideal target line of the vehicle (usually the center of the lane), the lane departure warning is usually disabled, so that the determination of the direction of travel is again essentially incumbent on the driver. Such a lane departure warning is for example in the US Pat. No. 6,487,501 B1 shown.

at Try with conventional lane keeping assistants However, it is emphasized that the driver contributes the vehicle steering activated Lane Keeping Assist as "unbalanced", what an undesirable and unfamiliar steering feel leads.

task the invention is to control a vehicle lane departure warning that gives the driver a familiar and safe steering feel becomes.

• a) Ermitteln einer Ist-Position sowie einer Soll-Fahrlinie des Fahrzeugs;
• b) Bestimmen einer Querabweichung des Fahrzeugs unter Berücksichtigung der Ist-Position und der Soll-Fahrlinie;
• c) Aktivieren des Spurhalteassistenten, sobald die Querabweichung einen vordefinierten Schwellenwert übersteigt; und
• d) Deaktivieren des Spurhalteassistenten bevor die Ist-Position des Fahrzeugs die Soll-Fahrlinie erreicht.

According to the invention, this object is achieved by a method for controlling a lane departure warning system in a vehicle, the method comprising the following steps:

• a) determining an actual position and a desired driving line of the vehicle;
• b) determining a transverse deviation of the vehicle taking into account the actual position and the target driving line;
• c) activating the lane departure warning as soon as the lateral deviation exceeds a predefined threshold; and
• d) deactivating the lane departure warning before the actual position of the vehicle reaches the target line.

By Carelessness of the driver exceeds the transverse deviation of the vehicle the predefined threshold, whereby the lane departure warning is activated in a known manner. As the measures of Lane departure warning to correct the direction of travel usually not abrupt, but gradually increasing, the vehicle will not engage until the Lane Keeping Assist has been activated Reach maximum deviation and then, controlled by the lane departure warning, again the desired driving line of the Approach the vehicle until it is reached. The attention The driver will usually shortly after the activation of the Lane departure warning or shortly after reaching the maximum transverse deviation increase again so far that he is again "ready to steer" after a period of carelessness. The vehicle will run at this time as a result of as before activated Lane Keeping Assist an "automatic Cornering "towards the lane center through. In the usual However, the driver is used to driving, for example through the centering of a power steering, that the steering power is symmetrical increases to a straight ahead of the vehicle. Accordingly are the "automatic cornering" and the necessary, manual Steering force for a straight ahead of the vehicle for the driver unfamiliar and lead to an unbalanced Steering impression. To this unwanted steering feeling to avoid the driver, the invention proposes Already deactivate the Lane Keeping Assist before the actual position of the vehicle reaches the target driving line.

Preferably the lane departure warning will not be deactivated until the Vehicle already moved towards the target driving line. For this is provided that the transverse deviation of the vehicle after activation of the lane departure warning in step c) a lateral deviation maximum reached and then decreases, the transverse deviation maximum is detected at least approximately.

After reaching the transverse deviation maximum, the vehicle approaches the target driving line again. This movement toward the target driving line is maintained even with deactivation of the lane departure warning, since the vehicle is usually applied after the deactivation of the lane departure warning by the centering of the power steering in a straight ahead. However, this straight-ahead travel also leads, after exceeding the transverse deviation maximum, to a movement in the direction of the desired driving line. This approach to the target line may be slow But instead of an active cornering with activated lane departure warning, but gives the driver a familiar steering feel. The driver is at any time free to accelerate the approach to the nominal driving line by means of a manually applied steering angle. By the earlier shutdown of the lane departure warning so safe tracking and occupant safety is impaired in any way, but only improves the steering feel for the driver, which leads to an overall better road safety.

Especially is the lane departure warning in step d) at the end of a predefined Time interval deactivated, the time interval preferably after detection of the cross deviation maximum starts to run.

The addressed, predefined time interval is preferably below one second. Particularly preferably, the time interval is in the range from 0.15 s to 0.35 s, for example 0.25 s.

In In a variant of the method, the transverse deviation maximum is determined in the step c) at least approximately by means of a transverse deviation rate determined, wherein the transverse deviation maximum is considered reached when the amount of lateral deviation below a predefined limit sinks. The determination of the lateral deviation maximum using the lateral deviation rate is sensory with very little effort feasible. Of course, the transverse deviation maximum but also directly or by means of further or other auxiliary quantities be determined. The limit value of the lateral deviation rate may be below 0.3 m / s, preferably below 0.2 m / s. The closer this one Limit value is 0, the more accurate is the lateral deviation maximum determine. However, a particularly accurate determination of the transverse deviation maximum is usually not necessary and due to the sensors used also only limited possible. The above mentioned Limit of about 0.2 m / s usually allows a sufficient accurate determination of the transverse deviation maximum.

In Another variant of the method is the lane departure warning in Step d) is deactivated if the transverse deviation is the predefined one Threshold again falls below. This condition for deactivation of the Lane Keeping Assist may work with the condition be linked to a predefined time interval. So For example, it is conceivable that the lane departure warning will not be deactivated when a predefined time interval expires after the cross deviation maximum is detected and, moreover, the transverse deviation is the predefined one Threshold falls below. Alternatively, an "OR link" is also conceivable, Lane Keeping Assist is disabled when a predefined Time interval expired after acquisition of the cross deviation maximum or if the lateral deviation is the predefined threshold falls below again.

In a further embodiment is in step c) a Steering system of the vehicle actively actuated by the lane departure warning. This is a particularly appropriate option for passenger cars, to influence the direction of travel of the vehicle. Especially at Trucks can affect the direction of travel alternatively or additionally by an asymmetrical brake control respectively.

For the case that the lane departure warning system is a steering system of the vehicle actuated, generates the steering system in step c) when exceeded a first predefined threshold value of the lateral deviation Lane keeping assistance torque, wherein the lane keeping assistance torque preferably between the first threshold and an amount larger, second predefined threshold the transverse deviation increases and when the second Threshold remains substantially constant.

The The invention further relates to a lane departure warning system of a vehicle.

Further Features and advantages of the invention will become apparent from the following Description of preferred embodiments with reference on the drawings. In these show:

1 a sketch of the method of the invention underlying the vehicle model with relevant geometric and physical variables;

2 an exemplary characteristic of a lane keeping assistance torque for the inventive method and the lane departure warning according to the invention;

3 a block diagram illustrating a variant of the method according to the invention;

4 a flow chart with respect to a range "A" of the block diagram according to 3 ;

5 a diagram in which, in carrying out the method according to the invention, different quantities are plotted over time; and

6 a diagram in which in carrying out the method according to the invention, the transverse deviation and the lane keeping assistance Mo are plotted over time.

The 1 schematically shows a simplified vehicle 10 with a focus S on a roadway 12 in an actual position 14 , where the actual position 14 of the vehicle 10 z. B. is defined as the position of the center of gravity S. Furthermore, a target driving line 16 drawn, which exactly like the actual position 14 is determined in a known manner by means of at least one suitable vehicle sensor. A corresponding vehicle sensor system has, for example, a video camera which detects lane markings and from this the actual position 14 and the target driving line 16 of the vehicle 10 can calculate.

• – Ein Gierwinkel Ψ des Fahrzeugs 10 ist der Relativwinkel zwischen der x_E-Achse des ersten Koordinatensystems und der x_V-Achse des zweiten Koordinatensystems;
• – ein Schwimmwinkel β des Fahrzeugs 10 ist der Relativwinkel zwischen der x_V-Achse des zweiten Koordinatensystems und einem Fahrzeuggeschwindigkeitsvektor v = [v_X v_Y]^T,
• – an einem Fahrzeugrad greifen longitudinale Kräfte F_X,f, F_X,r an;
• – an einem Fahrzeugrad greifen laterale Kräfte F_Y,f, F_Y,r an;
• – am Fahrzeug ist ein Lenkwinkel bzw. Radwinkel δ_W eingestellt;
• – am Fahrzeug ist ein Lenkradwinkel δ_H eingestellt;
• – als Verhältnis von Lenkradwinkel δ_H zu Lenkwinkel δ_W ist eine Lenkübersetzung i_S eingezeichnet;
• – die Vorder- und Hinterachse weisen zum Fahrzeugschwerpunkt S einen Abstand I_f bzw. einen Abstand I_r auf;
• – ein vordefinierter Vorausschaupunkt P weist zum Fahrzeugschwerpunkt S einen Abstand I_p auf, wobei der Vorausschaupunkt P ein fahrzeugfester Referenzpunkt ist;
• – eine Querabweichung Δr ist der Abstand des Punktes (x_C, y_C) = (0, 0) des dritten Koordinatensystems zur Achse x_V des zweiten Koordinatensystems.

In addition, in 1 drawn three coordinate systems and geometric and physical variables, which are helpful for the description of the vehicle situation. The coordinate axes x _E and y _E define a global, "earth-fixed", first coordinate system. A second coordinate system with the axes x _V and y _V is referred to as "vehicle-fixed" vehicle coordinate system and refers to the vehicle center of gravity S. On the target driving line 16 of the vehicle 10 Finally, a third coordinate system with the axes x _C and y _{C is} defined. Usually, the desired driving line corresponds 16 essentially a lane center of the roadway 12 , As in 1 to see the vehicle 10 considered as an example and simplifying according to the single-track model according to Riekert and Schunck, which summarizes the wheels on the front and rear axles in each case to a single wheel. The vehicle physical variables are defined as follows:

• - A yaw angle Ψ of the vehicle 10 is the relative angle between the x _E axis of the first coordinate system and the x _V axis of the second coordinate system;
• - A float angle β of the vehicle 10 is the relative angle between the x _V axis of the second coordinate system and a vehicle speed vector v = [v _X v _Y ] ^T ,
• On a vehicle wheel engage longitudinal forces F _{X, f} , F _{X, r} ;
• On a vehicle wheel engage lateral forces F _{Y, f} , F _{Y, r} ;
• - On the vehicle, a steering angle or wheel angle δ _{W is} set;
• - On the vehicle, a steering wheel angle δ _{H is} set;
• - As a ratio of steering wheel angle δ _H to steering angle δ _W is a steering ratio i _S drawn;
• - The front and rear axle have to the vehicle center of gravity S a distance I _f and a distance I _r on;
• A predefined look-ahead point P points to the vehicle center of gravity S a distance I _p , wherein the look-ahead point P is a vehicle-fixed reference point;
• A transverse deviation Δr is the distance of the point (x _C , y _C ) = (0, 0) of the third coordinate system to the axis x _{V of} the second coordinate system.

At a predetermined distance from the actual position 14 of the vehicle 10 (Predictive distance I _p ), for example, using a video camera, the transverse deviation .DELTA.r of the vehicle 10 from the target driving line 16 determined. This transverse deviation .DELTA.r is thus available as a sensor signal, preferably for torque superimposition in an active steering system. As soon as the lateral deviation Δr exceeds a predefined threshold value Δr _{S of} the lateral deviation Δr, a lane-keeping assistant of the vehicle becomes available 10 activated. Lane departure warning is to be understood as a structural unit that records relevant physical variables in a passive state and checks predetermined conditions. In addition, in an active state, the assembly actively affects the direction of travel of the vehicle 10 , Depending on whether or not the physical quantities meet the specified conditions, the lane departure warning system is in the passive or active state. For influencing the direction of travel, for example, a steering system of the vehicle 10 actively actuated by the lane departure warning, preferably by means of in 1 shown sizes. The steering system then generates a lane keeping assistance torque T _UM when the predefined threshold Δr _{S of} the transverse deviation Δr is exceeded.

In 2 a possible course of the lane keeping assistance torque T _{UM is} plotted against the transverse deviation Δr. The lane-keeping assistance torque T _UM monotonously increases between a first threshold value Δr _S1 and an absolute second predefined threshold value Δr _S2 and remains substantially constant at a predetermined level of a maximum assist torque T _MAX when the second threshold value Δr _{S2 is} exceeded.

The 3 shows a block diagram with a schematic representation of the method for controlling the lane departure warning in the vehicle 10 according to a preferred variant of the method. In particular, the illustrated procedure relates to the deactivation of the lane departure warning, since it is assumed that a lane keeping assistance torque T _UM ≠ 0.

In addition to the lane keeping assistance torque T _UM , the transverse deviation Δr, a predefined limit Δṙ _{G of} a lateral deviation rate Δṙ and a predefined time interval t _V are also used as further input signals. In this variant of the method, the transverse deviation Δr of the driving increases zeugs 10 after activation of the lane departure warning to a lateral deviation maximum Δr _MAX (cf. 5 and 6 ) and then decreases, wherein the lateral deviation maximum Δr _{MAX is} approximately detected and the lane departure warning is deactivated with expiration of the predefined time interval t _V after detection of the lateral deviation maximum Δr _MAX .

According to 3 the transverse deviation maximum Δr _{MAX is determined} using the derivation of the transverse deviation Δr, that is to say the so-called transverse deviation rate Δṙ. The amount of the determined lateral deviation rate | Δṙ | be less than or equal to the predefined limit Δṙ _G and at the same time a lane keeping torque T _UM ≠ 0 are present so that a flag D is set. The smaller is the amount of the pre-defined limit value .DELTA.R _G is set to the lateral deviation rate .DELTA.R, the more accurately corresponds to the time at which the flag D is set, the reaching of the maximum transverse deviation .DELTA.R _MAX.

The 4 shows a flow chart for the inventive method, with reference to the in 3 area marked "A". Setting the flag D also sets a time counter t _int = t. If t ≥ t _int + t _V , another flag F is set to the value 1. As soon as the flag F assumes the value 1, the lane departure warning is deactivated and the flag F is set to 0 again. The procedure for this procedure for setting the flags D and F is shown in the flowchart of FIG 4 shown in detail.

The 5 indicates the course of the lateral deviation Δr, the lateral deviation rate Δṙ and the lane keeping assist torque T _UM over the time t when the lane departure warning is driven in accordance with the above-mentioned method. Furthermore, the limit values Δṙ _{G of} the lateral deviation rate Δṙ and the times for setting the markers D and F are also drawn.

The peculiarity of the method for controlling the lane departure warning system is that the lane keeping assistance torque T _UM already drops to 0 before the vehicle 10 his desired driving line 16 (Δr = 0) has reached.

In other words, the lane departure warning is already deactivated before the actual position 14 of the vehicle 10 the target driving line 16 reached. By such, compared to the prior art preferred switching off the lane departure warning the above-mentioned advantages are achieved in terms of driving feeling. Decisive for the deactivation of the lane departure warning are in the illustrated process variant, the at least approximately detection of the transverse deviation maximum Δr _MAX and a predefined time interval t _V. After expiration of this time interval t _V , starting from the time of detection of the lateral deviation maximum Δr _MAX , it is ensured during the deactivation of the lane departure warning that the vehicle 10 even without active tracking towards the desired driving line 16 moved. Thus, even with early deactivation of the lane departure warning maximum vehicle safety is maintained.

The lane departure warning is preferably deactivated at the latest when the transverse deviation Δr exceeds the predefined threshold value Δr _S (FIG. 6 : Δr _S ≈ 0.5 m) again falls below. This is in 6 indicated by the dotted line T ' _UM .

Although the numerical values in the 5 and 6 are only to be understood as examples and depend on the particular type of vehicle and the design of the vehicle steering system or the vehicle brake system, the following numerical values have proven to be suitable and advantageous in their magnitude. So z. B. the predefined time interval t _V preferably less than a second, more preferably it is in the range of 0.15 s to 0.35 s, in particular at 0.25 s.

The limit value Δṙ _{G of} the transverse deviation rate Δṙ is preferably less than 0.3 m / s, more preferably less than 0.2 m / s.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 6487501 B1 [0003]

Claims (12)

Method for controlling a lane departure warning system in a vehicle ( 10 ), the method comprising the steps of: a) determining an actual position ( 14 ) as well as a nominal driving line ( 16 ) of the vehicle ( 10 ); b) determining a transverse deviation (Δr) of the vehicle ( 10 ) taking into account the actual position ( 14 ) and the desired driving line ( 16 ); c) activating the lane departure warning as soon as the lateral deviation (Δr) exceeds a predefined threshold (Δr _S ); and d) deactivating the lane departure warning before the actual position ( 14 ) of the vehicle ( 10 ) the desired driving line ( 16 ) reached. Method according to claim 1, characterized in that the transverse deviation (Δr) of the vehicle ( 10 ) reaches a lateral deviation maximum (Δr _MAX ) after activation of the lane departure warning in step c) and then decreases, whereby the lateral deviation maximum (Δr _MAX ) is detected at least approximately and the lane departure warning is deactivated only when the vehicle is moved in the direction of target driving line. A method according to claim 1 or 2, characterized in that the lane departure warning in step d) with the expiry of a predefined time interval (t _V ) is deactivated. A method according to claim 2 or 3, characterized in that the deactivation of the lane departure following the detection of the transverse deviation maximum (Δr _MAX ). Method according to claim 3 or 4, characterized in that the predefined time interval (t _V ) is less than 1.0 s, preferably about 0.15 s to 0.35 s. Method according to one of claims 2 to 5, characterized in that the transverse deviation maximum (Δr _MAX ) in step c) at least approximately by means of a lateral deviation rate (Δṙ) is determined, wherein the transverse deviation maximum (Δr _MAX ) is considered reached when the amount of the lateral deviation rate (| Δṙ |) falls below a predefined limit (Δr _G ). A method according to claim 6, characterized in that the limit value (Δr _G ) of the transverse deviation rate (Δṙ) is less than 0.3 m / s, preferably less than 0.2 m / s. Method according to one of the preceding claims, characterized in that the lane departure warning in step d) is deactivated when the transverse deviation (Δr) falls below the predefined threshold value (Δr _S ) again. Method according to one of the preceding claims, characterized in that a steering system of the vehicle ( 10 ) in step c) is actively actuated by the lane departure warning. Method according to Claim 8, characterized in that the steering system generates a lane-keeping assistance torque (T _UM ) in step c) when a first predefined threshold value (Δr _S1 ) of the transverse deviation (Δr) is exceeded, the lane-keeping assistance torque (T _UM ) between the first threshold value (T _UM ) Δr _S1 ) and a magnitude greater, second predefined threshold value (Δr _S2 ) of the transverse deviation (Δr) increases and remains substantially constant when the second threshold value (Δr _S2 ) is exceeded. Lane departure warning of a vehicle, with a controller and at least one sensor for determining an actual position ( 14 ) and a desired driving line ( 16 ) of the vehicle, wherein the control is arranged such that the lane departure warning is activated as soon as the transverse deviation (Δr) exceeds a predefined threshold value (Δr _S ) and is deactivated before the actual position ( 14 ) of the vehicle ( 10 ) the desired driving line ( 16 ) reached. Lane departure warning according to claim 11, with a Method according to one of claims 2 to 10 executable is.