WO2006081936A1

WO2006081936A1 - Method and device for carrying out an automatic steering intervention in particular for lane-keeping assistance

Info

Publication number: WO2006081936A1
Application number: PCT/EP2006/000341
Authority: WO
Inventors: Christophe Bonnet; Jens Desens; Hans Fritz
Original assignee: Daimlerchrysler Ag
Priority date: 2005-02-02
Filing date: 2006-01-17
Publication date: 2006-08-10
Also published as: DE102005004727A1

Abstract

The invention relates to a method and a device for support of a driver on driving along a laterally-defined lane (23). Support means (19) determine a set lane and trigger an automatic steering intervention depending on a deviation parameter describing the deviation between an actual lane of the vehicle and the set lane. According to the invention, the automatic steering intervention is carried out by determination of a set steering parameter (Ssoll), describing an additional set steering angle, or an additional set steering torque (Zsoll), which is used to set the additional set steering angle or the additional set steering torque (Zsoll) by means of an actuator (22). The type of automatic steering intervention depends on whether the value of the deviation parameter is greater than the value of at least one given deviation threshold value or not.

Description

Method and device for carrying out an automatic steering intervention, in particular for lane keeping assistance

The invention relates to a method for carrying out an automatic steering intervention according to the preamble of claim 1 and an apparatus for performing this method according to the preamble of claim 34.

Such a method and such a device are known from DE 199 43 410 Al. There, an additional steering torque is applied to the steering system to assist the driver when driving along a lane. This additional steering torque is changed at least as a function of the hand torque applied by the driver on the steering wheel. In addition to the manual torque, the steering speed with which the driver turns the steering wheel can also be taken into account. The greater the determined hand torque or the steering speed, the smaller is the additional steering torque applied to the steering system. This is to prevent that a generated for reducing the steering force servo assistance torque of the steering system and the additional steering torque for lane keeping assistance mutually adversely affect and negatively affect the driver's perception of the steering feel.

Proceeding from this, it can be regarded as an object of the invention, a method and a device for carrying out to provide an automatic steering intervention, with an improved adaptation to the driving style of the driver is possible.

This object is achieved by a method having the features of claim 1 and a device having the features of claim 34.

According to the invention, the type of automatic steering intervention depends on whether or not the magnitude of the deviation quantity is larger than the amount of at least one predetermined deviation threshold value. In the case of a deviation quantity whose magnitude is smaller than the magnitude of the at least one deviation threshold value or the magnitude of the at least one deviation threshold value, a first type of automatic steering intervention may take place, for example with an absolute limitation of the nominal steering variable to a first limit value, which is dependent on hand-torques. If the deviation quantity exceeds the at least one deviation threshold value according to magnitude, the automatic steering intervention is performed in a second type different from the first type, for example without limiting the nominal steering variable to the first limit value or by limiting the absolute value to a different one from the first limit value other and, in particular, a hand-independent limit.

Advantageous embodiments of the method according to the invention will become apparent from the dependent claims.

It is possible to predetermine the at least one deviation threshold value or to provide the deviation threshold variable and variable in particular by the driver. For example, the deviation threshold could be agreed limits are adapted by a driver operable adjuster to his personal driving style.

In this case, the at least one deviation threshold value can be predefinable as a function of parameters such as environmental parameters and / or vehicle parameters and / or driving state parameters such as vehicle longitudinal speed, vehicle longitudinal acceleration, vehicle lateral velocity, vehicle lateral acceleration, yaw rate, yaw acceleration and / or slip angle of the vehicle. For example, the amount of the at least one deviation threshold value can decrease in particular monotone decreasing with increasing vehicle longitudinal speed. A variant embodiment is also possible in which the deviation threshold value can assume different values as a function of the curvature of the desired lane or the roadway. In particular, these values can be changed separately by the driver. It is conceivable z. B. in that the deviation threshold value comprises a first value for straight travel which can be changed by the driver and a second value for cornering, which can be changed by the driver separately from the first value, in the case of a curved desired driving lane or roadway. As a result, in particular the different driving behavior when driving through curves can be taken into account and a "curve-cutting" driving style within specified limits can be made possible.

Moreover, it is advantageous if the at least one deviation threshold value depends on the vehicle geometry, in particular the width of the vehicle and / or the road surface and in particular the width of the roadway. The smaller the ratio of width of the vehicle to the width of the road, the smaller the amount of deviation threshold given value, in order to ensure a sufficiently good tracking.

The road condition - such. B. the width of the roadway - descriptive data can be transmitted by radio communication in the vehicle.

Characterized in that a seen in the direction of travel to the left permissible deviation descriptive left-side deviation threshold and the direction of travel to the right permissible deviation describing right-side deviation threshold are specified independently, there are improved customization options for the driver to his preferred driving style.

Furthermore, it may be advantageous if the target lane and / or at least one of the deviation threshold values are determined and / or changed as a function of an obstacle detected in the surroundings of the vehicle and / or of the type of obstacle. For example, the right-side deviation threshold value can be reduced or chosen to be very small when viewed to the right of the vehicle or in the direction of travel to the right of the desired lane of the vehicle, an obstacle -. B. another vehicle - was detected. This equally applies to the left-side deviation threshold. The location or the course of the desired lane on the road can also be moved to the left or right, if obstacles were detected. By this measure, the distance to the obstacle can be increased and the traffic safety can be increased. In the type of obstacle can be distinguished, for example, between cars and trucks. The lateral distance to be maintained can be greater in a truck than in a car. Advantageously, the ling-side deviation threshold value depends on the determined movement state of an obstacle seen in the direction of travel of the vehicle to the left or in front of the vehicle and / or the right-side deviation threshold of the determined movement state of an obstacle located to the right or in front of the vehicle as viewed in the direction of travel of the vehicle , As a result, in addition to the fact that an obstacle is present, even its state of motion, as z. B. whose obstacle longitudinal speed, obstacle longitudinal acceleration, obstacle lateral speed and / or obstacle lateral acceleration are taken into account in the determination of the permissible deviation between the sole lane and the actual lane, whereby a further improved traffic safety can be achieved.

In a simple way, the state of motion of an obstacle and / or the type of obstacle z. B. be determined by radio communication between the obstacle and the vehicle (11).

Furthermore, a retroactive effect on the steering wheel can occur during the automatic steering intervention. In an advantageous embodiment, a dynamic limit value is determined at least as a function of the manual torque in such a steering system for the target steering variable. The target steering variable is then limited to this dynamic limit. The target steering variable remains unchanged if the amount of the target steering variable is smaller than the amount of the dynamic limit value. Only when the amount of the target steering quantity should exceed the amount of the dynamic limit value, the target steering quantity is set equal to the current dynamic limit value. The additional desired steering angle described by the desired steering variable or the additional target steering torque described by the reference steering variable is therefore not constantly dependent on the manual torque. riiert, but only affected if the amount of Solllenkgrδße would exceed the dynamic limit. The limitation of the target steering amount is used to limit the amount caused by the automatic steering intervention reaction torque on the steering wheel, so that the driver is always able to control the vehicle and, if necessary, against the reaction torque occurring on the steering wheel to turn the steering wheel.

It is advantageous if the dynamic limit decreases with increasing magnitude of the manual torque and in particular decreases monotonically decreasing. This ensures that the retroactively acting on the steering wheel by the automatic steering engagement reaction torque is low in those cases where the driver performs a steering activity with high manual torque and / or large steering angles and / or high steering speeds. Sudden evasive maneuvers are characterized by high hand torques and / or high steering speeds. In these cases, no reaction torque on the steering wheel is to hinder the driver, so that moments of retroactivity due to automatic steering interventions are kept very low in terms of amount.

In this case, the dynamic limit value can be determined as a function of a fixed predefinable basic static limit value and a factor dependent on manual torque. Alternatively, it would also be possible to provide an addition or a subtraction instead of a multiplication of the basic limit value by a factor in which the basic limit value is increased or reduced by a value dependent on the manual torque.

It can also be provided that the limitation of the target steering variable to the dynamic limit value only takes place if the amount of the deviation quantity is smaller than the amount the predetermined deviation threshold or the amount of the predetermined deviation threshold. If the deviation quantity exceeds the deviation threshold value, then the automatic steering intervention takes place, for example, without limiting the nominal steering variable to the dynamic limit value or by limiting to another and in particular hand-torque independent limit value, which differs from the dynamic limit value.

Advantageously, the automatic steering intervention takes place only if the amount of the deviation quantity is greater than a predetermined deviation threshold value. In this way, smaller deviations of Istfahrspur be tolerated by the desired lane, without an automatic steering intervention would take place. This creates an optionally parameter dependent and, for example, the road course dependent tolerance range within which the driver can select the Istfahrspur the vehicle without causing a corrective steering intervention.

The fact that in addition to the automatic steering intervention a haptic feedback on the steering wheel and / or an audible and / or optical feedback to the driver is generated, the driver's warning about the occurred deviation from the target lane is improved, so that the traffic safety is increased ,

This haptic and / or acoustic and / or visual feedback is advantageously carried out only when the support means the beginning of leaving the lane was determined, for example, when the vehicle with the wheels of a vehicle side on or over the edge marker Roadway drives. The haptic or Acoustic or visual feedback takes place after the beginning of the automatic steering intervention.

The execution of the haptic feedback on the steering wheel may also begin when the amount of the deviation amount by a predetermined first difference value is greater than the amount of the at least one deviation threshold value. This measure provides a very simple triggering criterion for the haptic feedback.

In an advantageous embodiment, vibrations are applied to the steering wheel for haptic feedback. The amplitude and / or the frequency of these vibrations can be determined in particular as a function of the magnitude of the deviation variable, so that the haptic feedback on the steering wheel represents a measure of the deviation from the desired lane and also for the danger of the current driving situation.

Analogous to the triggering of the haptic feedback, the execution of the acoustic or the optical feedback can begin when the amount of deviation by a predetermined second difference value is greater than the amount of at least one deviation threshold, whereby a very simple triggering criterion for the acoustic or optical feedback present.

Because the amount of the second difference value is chosen to be greater than the amount of the first difference value, it is ensured that the acoustic and / or optical feedback takes place temporally after the haptic feedback and thus represents a further escalation stage, so to speak. Since all vehicle occupants are affected by an acoustic feedback, this feedback represents the last escalation onset and takes place temporally only after the automatic steering intervention and the haptic feedback.

Furthermore, it can be advantageous if the setpoint lane and / or at least one of the deviation threshold values are determined and / or changed as a function of an obstacle detected in the surroundings of the vehicle. For example, the right-side deviation threshold can be reduced or chosen to be very small if, viewed to the right of the vehicle or in the direction of travel, an obstacle to the right of the desired lane of the vehicle -. B. another vehicle - was detected. This equally applies to the left-side deviation threshold. The location or the course of the desired lane on the road can also be moved to the left or right, if obstacles were detected. By this measure, the distance to the obstacle can be increased and the traffic safety can be increased.

It is also expedient to carry out the automatic steering intervention only when the direction indicator has not been operated. As soon as the driver operates the direction indicator, a change of lane is to be assumed, so that an automatic steering intervention counteracting the departure of the current traffic lane is avoided.

It is further advantageous if the support means automatically switch to a passive operating state, if at least one of the subsystems of the assistance means is not working properly, and the support means switches to an active operating state if all subsystems of the support means are working properly. For example, a lane recognition device, which is a subsystem of the assistance means, can not identify a traffic lane in all driving situations. It then no automatic steering intervention for holding the current lane can be carried out because this lane was not recognized. One of the subsystems of the assistance means, therefore, does not operate properly, so that the assistance means switches to a passive operating state in which no automatic steering intervention takes place. Once all subsystems work properly again, there is an automatic switching of the support means in the active operating state, in which automatic steering interventions are possible.

It is also possible to limit the target steering variable for limiting the reaction torque during a switch-on period when switching on the assistance means to a switch-on limit value. Alternatively or additionally, the target steering quantity can also be limited to a switch-off limit value during a switch-off period when the assistance means are switched off. As switching on and off of the support means is to understand both the switching from the active to the passive operating state of the support means, as well as caused by the driver switching on and off of the support means, for example by switching on and off the ignition of the vehicle. It is also possible to turn on or off the support means by a corresponding operation via an operating element of the vehicle. In this way, the reaction torque is limited during the switch-on period or during the switch-off period, so that suddenly occurring or suddenly eliminated feedback moments on the steering wheel can be prevented.

In such an embodiment, the switch-on threshold and / or the switch-off threshold may have a time-dependent course. For example, the switch-on limit can be a rising ramp or the Ausschaltgrenzwert have a ramp-like gradient.

In the following, an embodiment of the method according to the invention is explained in more detail with reference to the accompanying drawings. Show it:

Fig. 1 is a schematic representation of a steering system of a vehicle and assistance means for assisting the driver when driving along a sidewise roadway in a block diagram-like representation;

Fig. 2 is a schematic representation of a target lane and an actual lane of the vehicle on a roadway in plan view

3 shows an embodiment of the dependence of a factor K on the amount of the manual torque H,

4 shows exemplary time profiles of a basic limit value GB, a dynamic limit value GD, a switch-on limit value GE, a switch-off limit value GA, an additional target steering torque Zsetpoint and an additional steering torque Zstell applied to the steering system by an actuating device,

Fig. FIG. 5 shows an exemplary embodiment of a function which shows the dependency of an additional desired steering torque Zsetpoint from the deviation D between the desired driving lane and the actual driving lane, and FIG

Fig. 6 shows an exemplary course of a first and a second oscillation, which serve as haptic feedback on the steering wheel.

7 shows the dependence of a left-side deviation threshold value and a right-side deviation threshold value on the vehicle longitudinal speed In Fig. 1, the structure of a steering system 10 of a vehicle 11 is shown schematically. A steering wheel 12 is connected via a steering column 13 to a steering actuator 14, which serves for the deflection and thus for setting a steering angle LW to the steerable wheels 15 - in particular the front wheels - of the vehicle 11.

In the preferred exemplary embodiment, the vehicle 11 has a lane keeping system 20, which transmits a setpoint steering variable Ssetpoint to a control unit 21. The target steering variable Sset here indicates an additional target steering torque Zsetpoint to be set which is to be adjusted by an adjusting device 22 on the steering system 10 in order to assist the driver when driving along a laterally delimited roadway 23. As an alternative to the preferred exemplary embodiment, instead of the additional nominal steering torque Zsetpoint or in addition to the additional target steering torque Zsetpoint, an additional target steering angle could also be preset by the nominal steering variable Ssetpoint.

The steering system 10 further comprises a manual torque sensor 27, which detects the hand torque H exerted by the driver on the steering wheel 12 and transmits it to the control unit 21.

As an alternative to measuring the hand torque H by means of the hand torque sensor 27, the hand torque H can also be estimated on the basis of a model.

The control unit 21 is also supplied with a correction signal C, which in the embodiment has a first correction value CG and a second correction value CK, can be changed by the setting on an operating unit 28 by the driver. The correction values CG and CK of the correction signal C will be discussed later. The lane keeping system 20, the control unit 21, the setting device 22 and the operating unit 28 are part of support means 19 for assisting the driver when driving along a laterally delimited roadway 23.

With reference to FIG. 2, the operation of the lane keeping system 20 will be explained. In the lane keeping system 20, on the basis of the information of a position detection unit 29, a set lane 30 on the lane 23 and the actual lane 31 actually driven by the vehicle are determined. The position detection unit 29 is used to determine the position of the vehicle 11 relative to the course of the lane 23 and has an image processing unit 29 in the embodiment described here. As an alternative or in addition to the image processing unit, the position detection unit 29 could also have satellite-based position recognition (for example GPS) and / or a sensor system cooperating with passive road marking elements such as magnetic nails. According to the example, a communication device 51 communicating with active roadway marking elements 39, such as roadway beacons and / or with obstacles 50, like other vehicles, is also provided.

The desired lane 30 can be determined in addition to the determined road course depending on detected obstacles 50. For recognizing the obstacles .50, the vehicle 11 can be equipped with an environment sensor system, whereby the image processing unit or the communication device 51, possibly provided for vehicle-vehicle communication, of the position detection unit 29 can also be used for obstacle detection.

Subsequently, a deviation describing the actual deviation between the desired driving lane 30 and the actual driving lane 31 will be described. determined from this deviation amount D, the set target steering variable Ssoll.

Instead of the current deviation quantity D, the future deviation quantity D * can also be used to calculate the target steering variable Sset, which can be determined, for example, as follows:

D * = D + -a (x *, Aψ _> p) (1)

With

D: current deviation quantity which describes the actual deviation between the nominal lane 30 and the actual lane 31 measured perpendicularly to the nominal lane 30, x *: a distance which can be predetermined in the direction of travel of the vehicle 11,

Aψ: angle between the desired lane 30 and the actual lane 31 of the vehicle 11, p: curvature of the desired lane 30 or the lane 23, α: predeterminable first functions depending on the distance x *, the angle Δ ^ and the curvature p.

From the equation (1), the equation is obtained by approximation

D * = D + x * -Aψ-x * ² φ ⁽ 1 ')

The distance x * can be specified dependent parameters, for example, depending on the vehicle longitudinal speed v and / or the vehicle longitudinal acceleration a.

On the basis of the target steering variable Ssoll then an automatic steering intervention is performed, while doing the steering system 10 acting additional steering torque Zsteil is directed such that the current deviation between the desired lane 30 and the actual lane 31 is reduced. In the driving situation illustrated in FIG. 2, therefore, an additional steering torque Zstell is applied, which causes a steering angle of the steerable vehicle wheels 15 in the direction of travel to the left, in order to align the actual driving lane 31 with the desired driving lane 30 again.

When steering system 10, the steering wheel 12 and the steerable vehicle wheels 15 are mechanically connected to each other, so that during the automatic steering engagement, a reaction torque R is caused on the steering wheel 12. In order not to irritate the driver and to leave him the sovereignty over the vehicle 11 in each driving situation, it is provided according to the invention to limit the retroactive effect R in terms of amount. This is achieved by limiting the amount of the target steering variable Ssoll determined and requested by the lane keeping system 20. To limit the nominal steering quantity Sset or. of the additional desired steering torque Zsoll described by the target steering variable Ssoll, a dynamic limit value GD in the control unit 21 is calculated as a function of the manual torque H detected or estimated by the manual torque sensor 27, to which the sole steering variable Ssetpoint resp. the additional target torque Zsoll is limited, whereby, for example, the limited additional target torque Zlim is formed. The limited additional target torque Zlim is described by a drive current I driving the setting device 22 and applied to the steering system 10 by the setting device 22 as additional steering torque Zstell.

The dynamic limit value GD decreases in magnitude with increasing amount of the manual torque H. The greater the amount of the manual torque H on the steering wheel 12, the smaller is the maximum possible, by the adjusting device 22 of the Un. support means 19 set additional steering torque Zstell. In the embodiment described here, the dynamic limit value GD is calculated as follows:

GD = K (H) - GB (2) with

K (H): factor H depending on the manual torque H,

GB: fixed basic limit.

Fig. 3 shows the dependence of the factor K on the amount of the manual torque H. For manual torques H which are smaller in magnitude than the amount of a lower manual torque limit Hmin, the factor K assumes the value one, so that the dynamic limit value GD is equal to the fixed base limit value GB. If the magnitude of the manual torque H is greater than or equal to the lower manual torque limit Hmin and less than an upper manual torque limit Hmax, then the factor K assumes values between zero and one, decreasing monotonically with increasing magnitude of the manual torque H. In the example in FIG. 3, the factor K linearly decreases in the range from the lower manual torque limit Hmin to the upper manual torque limit Hmax with increasing magnitude of the manual torque H. In this range, any other falling function for the factor K could be specified instead of the linear curve. For manual torques which correspond at least to the upper manual torque limit value Hmax, the factor K assumes the value zero, so that no automatic steering intervention can take place. Alternatively, the factor K for amounts of the manual torque greater than or equal to the upper manual torque limit Hmax could also be set to a minimum value greater than zero.

In Fig. 4, the exemplary time profile of the dynamic limit value GD (dotted line) is shown. The GE- dashed line shows the exemplary time course of the track holding system 20 to the controller 21 transmitted Zusatzsolllenkmoments Zsoll. The limited in the control unit 21 Zusatzsolllenkmoment Zlim or set by the adjusting device 22 additional steering torque Zstell are indicated by the solid line in FIG. 4 shown.

As an initial situation to FIG. 4, it is assumed that the driver has switched on the assistance means 19 in order to obtain assistance when driving along a laterally delimited roadway 23. However, before a first time tθ, at least one subsystem of the assistance means 19 is not ready for operation or does not function properly. For example, this is the case when no marked lane 23 can be detected by the lane keeping system 20 or its image processing unit 29. In this case, the support means 19 automatically switch to a passive operating state in which no automatic steering intervention is performed.

For the first time tθ, assume that all subsystems of the support means 19 are operating properly, i. H . The lane keeping system 20 can also determine a marked lane 23 so that the assistance means 19 switch from the passive operating state to the active operating state in which an automatic steering intervention can take place. During a switch-on period from the first time t.sub.θ, the limited additional target steering torque Zlim transmitted by the control unit 21 to the adjusting device 22 is limited by a monotonically increasing turn-on limit value GE, which increases linearly from the value zero to, for example. This is to prevent that at the first time tθ immediately a larger reaction torque R is applied to the steering wheel 12. Due to the increasing switch-on threshold GE, this will possibly present, set by the adjusting device 22 additional steering torque Zstell and thus also the reaction torque R on the steering wheel 12 continuously increased so as not to irritate the driver.

At a second time t 1, the switch-on limit value GE corresponds to the additional nominal torque Zsoll required by the lane-keeping system 20. At this time, the turn-on period is ended and the limit by the turn-on threshold GE is canceled.

After the second time tl that corresponds to the control unit

21 limited Zusatzsolllenkmoment or set by the adjusting additional steering torque Zstell the requested by the lane keeping system 20 Zusatzsolllenkmoment Zsoll, since the required by the lane keeping system 20 Zusatzsolllenkmoment Zsoll is below the dynamic limit value GD.

At a third time t2, the additional target steering torque Zsoll requested by the lane keeping system 20 exceeds the dynamic limit value GD. From this third point in time t2, the limited additional target steering torque Zlim or the additional steering torque Zstell set by the adjusting device 22 corresponds to the current value of the dynamic limit value GD which is determined by the torque depending on time.

Once the requested by the lane keeping system 20 Zusatzsolllenkmoment Zsoll falls below the dynamic limit GD, also corresponds to the limited additional control torque in the control unit 21 Zlim and that by the adjusting device

22 set additional steering torque Zstell again this requested value of Zusatzsolllenkmoments Zsoll. This is shown in FIG. 4 from a fourth time t3 the case. It is assumed that at a fifth time t4 one of the subsystems of the assistance means 19, for example the lane keeping system 20, no longer operates properly. This can be z. B. be the case when the image processing unit 29 can not detect a marked lane 23. At this fifth time t4, a switch-off period begins, during which the limited additional target steering torque Zlim transmitted by the control unit 21 to the adjusting device 22 and thus also the additional steering torque Zstell set by the adjusting device 22 are limited by a switch-off limit value GA which decreases linearly over time. The switch-off period ends at a sixth time t5 at which the limited additional target steering torque Zlim or the set additional steering torque Zstell assume the value zero. As already explained in connection with the switch-on period (t.sub.o-t.sub.1), during the switch-off period, it is prevented in the same way that an automatic steering intervention is suddenly terminated and thus unexpectedly for the driver. In order to avoid irritation in the driver, according to the invention a continuous reduction of the activated auxiliary steering torque Zstell is predetermined by the switch-off threshold GA.

It is understood that in a modification to the described embodiment, instead of the ramp-up rising threshold GE or instead of the ramp-down Ausschaltgrenzwertes GA also any other function with increasing or decreasing course could be specified.

The limitation of the limited additional target steering torque Zlim and the set additional steering torque Zstell during the switch-on period (tθ -tl) by the switch-on threshold GE and during the switch-off period (t4-t5) by the output switching limit value GA also takes place when the driver is switched on or off, for example by a corresponding operation of the operating unit 28. Switching off the assistance means 19 can also be provided when a vehicle deceleration is requested or set that exceeds a delay threshold. The requested vehicle deceleration can be derived, for example, from the brake pedal position and / or from the brake pressure in the master brake cylinder and / or in the wheel brake devices. The currently existing Fahrzeugverzδgerung can also be measured directly by means of a longitudinal acceleration sensor.

The limits of the limited Zusatzsolllenkmomentes Zlim and the set additional steering torque Zstell during the switch-on (tθ -tl) by the switch-GE and during AusschaltZeitraumes (t4 - t5) by the Ausschaltgrenzwert GA can also merge into each other. This is the case, for example, when during the switch-on period one of the subsystems of the assistance means 19, for example the lane keeping system 20, no longer operates properly and an automatic switchover from the active to the passive operating state takes place. Similarly, during the switch-off period, the support means 19 can be switched over from the passive to the active operating state.

The manner of performing the automatic steering intervention may also depend on the deviation amount D or D *, which describes the deviation between the desired lane 30 and the actual lane 31, for example, whether or not the amount of the deviation quantity D, D * exceeds a deviation threshold value. According to the example, a left-side deviation threshold value YL describing the left-permitted deviation in the direction of travel of the vehicle 11 and a right-side deviation threshold value YR describing the rightward deviation as seen in the direction of travel are specified independently of each other.

The right-side deviation threshold YR and the left-side deviation threshold YL can either be fixed or - as in the embodiment described here - be variably adjustable. Via the operating unit 28, the driver has the option of independently adapting the deviation threshold values YR, YL to his driving style by setting the correction values CK, CG in a predetermined range and thereby slightly increasing or decreasing the tolerance range.

Via the first correction value CG, the driver can change or adapt the right-side deviation threshold value YR and the left-side deviation threshold value YL, in particular independently of one another for straight-ahead travel - ie for curvatures p of the vehicle lane 30 or the roadway 23 below a curvature threshold value. The second correction value CK serves to set the right-side deviation threshold value YR and the left-side deviation threshold value YL, in particular, independently of one another for cornering, ie, at curvatures p of the setpoint lane 30 or the lane 23, which corresponds at least to the curvature threshold value.

The left-side and / or the right-side deviation threshold value YL or YR can be determined or changed as a function of one or more detected obstacles 50. the. By way of example, the deviation threshold value YL or YR in question can be limited or reduced if an obstacle 50 on the corresponding side of the vehicle has been recognized in the direction of travel of the vehicle 11. To detect the obstacles 50, the vehicle 11 has an environment sensor system, in which case the communication device 51 of the position detection unit 29 is used for obstacle detection.

Via the communication device 51, the vehicle 11 receives information about the type of obstacle 50, that is to say, for example, whether it is a one-lane or two-lane vehicle, a lorry with or without a trailer or a semitrailer. Furthermore, the movement state of the obstacle 50 is also detected by the radio communication with the obstacle 50 by means of the communication device 51 and the obstacle longitudinal speed and / or the obstacle lateral velocity and / or the obstacle longitudinal acceleration and / or the obstacle lateral acceleration describing motion state data is determined.

It is further provided that via the communication device 51 and the road surface of the roadway 23, such. B. the width or curvature p of the roadway 23 is determined. For this purpose, the communication device 51 establishes a radio link to the active lane marking element 39 formed by a lane beacon. The road condition could alternatively be determined by another environment sensor.

The left-side and right-side deviation thresholds YL, YR are now calculated as a function of one or more of the following parameters:

^■ the road surface,

^■ the movement state of the obstacle 50, ■ Driving condition parameters such as vehicle longitudinal speed, vehicle longitudinal acceleration, vehicle lateral velocity, vehicle lateral acceleration, vehicle yaw rate, vehicle yaw acceleration and / or vehicle float angle.

FIG. 7 shows an exemplary dependency of the deviation threshold values YL, YR on the vehicle longitudinal speed v, the amount of the left-side and right-side deviation threshold values YL and YR decreasing monotonically with increasing magnitude of the vehicle longitudinal velocity v and, for example, linearly decreasing.

In the in Fig. In the embodiment shown by solid lines, automatic steering intervention for lane keeping assistance is performed only when the deviation amount D, D * is greater in magnitude than the predetermined right-side deviation threshold YR or the left-side deviation threshold YL. In this way, around the target lane 30 around a tolerance range, within the deviations between the desired lane 30 and the actual lane 31 are tolerated without an automatic steering intervention would take place. In this way, the driver of the vehicle 11 has the ability to vary the actual lane 31 on the lane 23 within the tolerance range, without triggering an automatic steering intervention. If the deviation quantity D, D * amounts to the right-side deviation threshold value YR or the left-side deviation threshold value YL, the target steering variable Ssetpoint or the additional target steering torque Zsetpoint increases continuously with increasing magnitude of the deviation quantity D, D * and, for example, linearly. Due to the fact that two deviation threshold values YR, YL are predetermined, the tolerance range relative to the nominal driving lane 30 can be different. Consequently, it is possible to predetermine an asymmetrical tolerance range with respect to the reference lane 30.

As an alternative to the possibility of performing an automatic steering intervention for lane keeping assistance only if the deviation quantity D, D * is greater than one of the deviation threshold values YL or YR, it is also possible to carry out the automatic steering intervention for lane keeping assistance, even if the deviation quantity D, D * is smaller than the predetermined right-side deviation threshold YR or the left-side deviation threshold YL or the right-side deviation threshold YR or the left-side deviation threshold YL, respectively. In a preferred variant of the method, the limitation of the setpoint steering variable Ssetpoint to the dynamic limit value then takes place. If the amount of the deviation amount D, D * exceeds the amount of the right-side deviation threshold YR or the left-side deviation threshold YL, then automatic steering intervention is performed without limiting the target steering amount Ssetpoint to the dynamic limit value GD, as shown by the dashed line in FIG the hatched area is shown. In this case, the target steering variable Ssetpoint can be limited to the basic limit value GB or another, hand-torque independent, predefinable limit value or remain unlimited.

Furthermore, the automatic steering intervention for lane keeping assistance is only performed when there is no actuation of the direction indicator of the vehicle 11. When the direction indicator is actuated, it is assumed that the driver wants to leave the current setpoint lane 30, then that no counter-acting automatic steering intervention takes place. Only after switching off the direction indicator, the lane keeping system 20 determines a new desired lane 30, are made on the basis of then any automatic steering intervention.

It can also be provided that an automatic steering intervention for lane keeping assistance only after a predetermined period of time after deactivating the direction indicator takes place. This can be useful, in particular, if the vehicle 11 has a direction indicator which triggers a predetermined number of blinker actuations by a single short actuation and then switches itself off automatically. In order to prevent too early automatic steering intervention with incomplete lane change, such automatic steering intervention can then be prevented during the predetermined period of time after switching off the direction indicator.

Alternatively or in addition to the additional desired torque Zsetpoint, the desired steering variable Ssetpoint can also describe an additional desired steering angle. This additional setpoint steering angle is then limited in the same way as described above using the additional setpoint torque Zsetpoint, wherein the control unit 21 then generates a limited additional setpoint steering angle, which is transmitted to the setting device 22 or another suitable steering actuator for setting the additional steering angle resulting therefrom , In this case, the limited additional target steering angle can be formed as follows:

LWZlim = LWZsoll for LWZsoll <GD '

LWZlim = GD 'for LWZsoll> GD' f- (3)

GD '= K (H) -GB' With

LWZlim: limited additional target steering angle,

LWZsoll: additional target steering angle,

GD ': dynamic auxiliary steering angle limit.

K (H): factor H depending on the manual torque H,

GB ': fixed additional steering angle basic limit.

In Equation (3), unlike FIG. 4, the dynamic auxiliary steering angle limit GD 'is formed by a steering angle amount and not by a torque magnitude. Otherwise, in connection with FIG. 4 described limiting method used analogously to the additional steering angle.

In particular, in the case of cascaded controllers which set both the additional steering angle and the additional steering torque-for example, in a subordinate regulator-a limitation of the additional target steering angle and of the additional nominal torque can take place, which leads to increased safety of the entire regulator structure.

In the exemplary embodiment, in addition to the automatic steering intervention via the adjusting device 22, a haptic feedback on the steering wheel 12 is generated, wherein the steering wheel in the circumferential direction is vibrated, so that the driver feels vibrations on the steering wheel 12. This is shown in FIG. 1 schematically represented by the double arrow 40. Furthermore, an audible and / or visual feedback to the driver is produced via a feedback unit 44.

The haptic feedback on the steering wheel 12 and the visual or audible feedback via the feedback unit 44 are triggered when the vehicle 11 threatens to leave the roadway 23 despite the automatic steering intervention. This can be determined by the position detection unit 29, for. B. if the vehicle is traveling on or over the left-side marker 41 or the right-side marker 42 of the lane 23.

In the preferred embodiment, the automatic steering intervention, the haptic feedback and the acoustic and / or optical feedback occur in chronological succession to form three escalation levels. If the amount of the deviation amount D, D * by a predetermined first difference value .DELTA.l is greater than the amount of the left-side deviation threshold YL or the right-side deviation threshold YR, the haptic feedback on the steering wheel 12 is carried out in magnitude and the amount of Deviation size D, D * then by a predetermined second difference value Δ2 greater than the amount of the left-side deviation threshold YL and the right-side deviation threshold YR, the driver is finally warned by the audible and / or visual feedback. In order to ensure the timed sequence of the feedback, the amount of the second difference value .DELTA.2 is greater than the amount of the first difference value .DELTA.l:

.DELTA.l | <| Δ2 | with Δl and Δ2> 0.

The difference values can be fixed or parameter dependent.

Fig. FIG. 6 shows the exemplary course of a first oscillation 45 and a second oscillation 46, which in each case have a sinusoidal profile with an amplitude A1 or -A2 and a period T, respectively. In Fig. 6, vibration values greater than zero mean a deflection of the steering wheel 12 in the direction of rotation to the left and vibration values smaller than zero a deflection of the steering wheel 12 in the direction of rotation to the right. If the vehicle 11 threatens to leave the lane 23 to the left when viewed in the direction of travel, oscillation values less than zero are predetermined (second oscillation 46) and if the vehicle 11 threatens to leave the lane 23 to the right in the direction of travel, oscillation values greater than zero are predetermined (first oscillation 45 ), so that also the haptic indicates the steering direction, in which the steering wheel 12 must be rotated to prevent accidental leaving of the lane 23. The oscillations 45 and 46 are superimposed on the current steering wheel position.

The frequency and the magnitude of the amplitude are determined as a function of the magnitude of the deviation quantity D, D *. The greater the magnitude of the deviation quantity D, D *, the greater the amount of the amplitude Al or A2 of the oscillation 45 or 46 is selected. At the same time, the frequency of the oscillation 45, 46 is increased with an increasing magnitude of deviation. The driver thus receives by the haptic feedback simultaneously information about how large the amount of deviation of the actual lane 31 of the target lane 30 is current. Thus, he is informed of the increasing danger of leaving the lane 23 via the haptic feedback.

It is understood that in a modification to this it would also be conceivable to generate a haptic feedback by a vibration that oscillates sinusoidally about the current steering wheel position in the direction of rotation of the steering wheel 12 both to the left and to the right.

Instead of the sinusoidal oscillations 45, 46, another oscillation profile for generating the haptic feedback can also be used. mentidung be specified on the steering wheel 12, such. B. a triangular or a sawtooth-shaped oscillation.

Claims

claims

1. A method for assisting the driver when driving along a laterally delimited roadway (23), in which the assistance means (19) determine a desired lane (30) and an automatic steering intervention as a function of the deviation between an actual actual lane (31) of the vehicle ( 11) and the reference lane (30) cause deviation (D, D *) to be carried out to carry out the automatic steering intervention to be set Zusatzsolllenkwinkel and / or a Zusatzsolllenkmoment (Zsoll) to be set target steering variable (Ssoll), for setting the Zusatzsolllenkwinkels or the Zusatz solllenkmoments (Zsoll) by an adjusting device (22) is used, characterized in that the type of automatic steering intervention depends on whether the amount of the deviation quantity (D, D *) is greater than the amount of at least one predetermined deviation threshold value (YR, YL) or not.

2. Method according to claim 1, characterized in that the at least one deviation threshold value (YR, YL) is variable and in particular changeable by the driver.

3. The method as claimed in claim 2, characterized in that the at least one deviation threshold value (YR, YL) is dependent on parameters such as environmental parameters (p) and / or vehicle parameters and / or driving state parameters such as vehicle longitudinal speed, vehicle longitudinal acceleration, vehicle lateral velocity, vehicle accelerator acceleration, yaw rate, Yaw acceleration and / or slip angle of the vehicle (11) can be predetermined.

4. The method according to claim 3, characterized in that the amount of the at least one deviation threshold value (YR, YL) decreases with an increasing amount of vehicle longitudinal speed (v) in particular monotonically decreasing.

5. The method according to claim 3 or 4, characterized in that the at least one deviation threshold (YR, YL) depending on the curvature (p) of the desired lane (30) or the roadway (23) can assume different values, which are determined by the driver can be changed separately.

6. The method according to any one of claims 1 to 5, characterized in that the at least one deviation threshold value (YR, YL) of the vehicle geometry, in particular the width of the vehicle (11) and / or the road surface and in particular the width of the roadway (23) depends.

7. The method according to claim 6, characterized in that the road condition as the width of the roadway (23) descriptive data is transmitted by means of radio communication in the vehicle (11)

8. The method according to any one of claims 1 to 7, characterized in that a seen in the direction of travel to the left permissible deviation descriptive left-side deviation threshold (YL) and a seen in the direction of travel to the right permissible deviation descriptive right-side deviation threshold (YR) independently can be specified.

9. The method according to any one of claims 1 to 8, characterized in that the target lane (30) and / or the deviation threshold (YL, YR) in response to a detected in the vicinity of the vehicle (11) obstacle and / or of the Art the obstacle detected and / or changed.

10. The method according to claim 9 in conjunction with claim 8, characterized in that the lens-side deviation threshold value (YL) depends on the determined state of movement of a vehicle viewed in the direction of travel of the vehicle (11) left next to or in front of the vehicle (11) located obstacle and / or the right-side deviation threshold value (YR) depends on the determined state of movement of an obstacle located to the right of or in front of the vehicle (11) when viewed in the direction of travel of the vehicle (11).

11. The method according to claim 10, characterized in that the movement state of an obstacle and / or the type of obstacle by means of radio communication between the obstacle and the vehicle (11) is determined.

12. The method according to claim 1, characterized in that the at least one deviation threshold (YR, YL) is fixed.

13. The method according to any one of claims 1 to 12, characterized in that during the automatic steering engagement, a reaction torque (R) on the steering wheel (12) of the vehicle (11) occurs.

14. The method according to claim 13, characterized in that a dynamic limit value (GD) for the target steering variable (setpoint) is determined, which is determined as a function of a by the driver on the steering wheel (12) exerted current manual torque (H), wherein the target steering amount ( Ssoll) to limit the reaction torque (R) during an automatic steering intervention to the dynamic limit (GD) is limited.

15. The method according to claim 14, characterized in that the amount of the dynamic limit value (GD) decreases with increasing amount of the manual torque (H).

16. The method according to claim 15, characterized in that the amount of the dynamic limit value (GD) decreases monotonically decreasing with increasing amount of the manual torque (H).

17. The method according to claim 14 or 15, characterized in that the dynamic limit value is determined depending on a fixed predetermined basic limit (GB) and a hand torque dependent factor (K).

18. The method according to any one of claims 14 to 17, characterized in that the limitation of the target steering variable (Ssoll) to the dynamic limit (GD) only takes place when the amount of the deviation amount (D, D *) is smaller than the amount of the predetermined Deviation threshold (YR, YL) or equal to the amount of the predetermined deviation threshold (YR, YL).

19. The method according to any one of claims 1 to 18, characterized in that the automatic steering intervention takes place only if the amount of the deviation quantity (D, D *) is greater than the amount of the at least one predetermined deviation threshold value (YR, YL) ,

20. The method according to any one of claims 1 to 19, characterized in that in addition to the automatic steering intervention hap- tische feedback on the steering wheel (12) and / or an audible and / or visual feedback is generated.

21. The method according to claim 20, characterized in that the haptic and / or the acoustic and / or the optical feedback is carried out only when by the support means (19) the beginning of the lane departure of the track (23) has been detected.

22. The method according to claim 20 or 21, characterized in that the haptic feedback is performed only when the amount of the deviation quantity (D, D *) by a predetermined first difference value (.DELTA.l) is greater than the amount of the at least one predetermined deviation threshold value (YR, YL).

23. The method according to any one of claims 20 to 22, characterized in that for haptic feedback vibration to the steering wheel (12) are applied.

24. The method according to claim 23, characterized in that the frequency and / or the amplitude of the vibrations of the amount of the deviation quantity (D, D *) depend.

25. The method according to claim 20 or 21, characterized in that the acoustic and / or optical feedback is performed only when the amount of the deviation quantity (D, D *) by a predetermined second difference value

(Δ2) is greater than the magnitude of the at least one predetermined deviation threshold (YR, YL).

26. The method of claim 25 in conjunction with claim 22, characterized in that the amount of the second difference value (.DELTA.2) is greater than the amount of the first difference value (.DELTA.l).

27. The method according to any one of claims 1 to 26, characterized in that the automatic steering intervention and / or the acoustic and / or visual feedback occurs only when the direction indicator has not been operated.

28. The method according to any one of claims 1 to 27, characterized in that the additional steering torque generated by the automatic steering intervention (Zstell) or the additional steering angle generated is directed such that the deviation between the desired lane (30) and Istfahrspur (31) is reduced.

29. The method according to any one of claims 1 to 28, characterized in that the support means (19) automatically switch to a passive operating state when at least one of the subsystems (20) of the support means (19) is not working properly, and that the support means (19) switch to an active operating state when all subsystems (20) of the support means (19) are operating properly.

30. The method according to any one of claims 1 to 29, characterized in that the target steering variable (Ssoll) for limiting the reaction torque (R) during a switch-on period (tθ to tl) when switching the support means (19) to a switch-on limit (GE) is limited ,

31. The method according to any one of claims 1 to 30, characterized in that the target steering variable (Ssoll) for limiting the reaction torque (R) during a switch-off period (t4 to t5) when turning off the support means (19) to a Ausschaltgrenzwert (GA) is limited ,

32. The method of claim 30 or 31, characterized in that the switch-on limit value (GE) and / or the Ausschalt- limit (GA) have a time-dependent course.

33. The method according to claim 32, characterized in that the amount of the switch-on limit value (GE) has a ramp-like rising and / or the amount of the switch-off limit value (GA) has a ramp-like slope.

34. A device for assisting the driver when driving along a laterally delimited roadway (23), wherein the support means (19) determine a desired lane (30) and an automatic steering intervention in response to a deviation between an actual actual lane (31) of the vehicle ( 11) and the reference lane (30) cause deviation (D, D *) to be carried out to carry out the automatic steering intervention to be set Zusatzsolllenkwinkel and / or a Zusatzsolllenkmoment (Zsoll) to be set target steering variable (Ssoll), for setting the Zusatzsolllenkwinkels or the auxiliary steering torque (Zsoll) by an adjusting device (22). is used, characterized in that the type of automatic steering intervention depends on whether the amount of the deviation quantity (D, D *) is greater than the amount of at least one predetermined deviation threshold value (YR, YL) or not.