DE102004023546A1 - Procedure for tracking and lane keeping system - Google Patents

Abstract

The invention relates to a method for tracking and a lane keeping system for a vehicle (5), wherein the reference lane (10) is determined and compared with the current direction of travel course (42). When the comparison result indicates that the vehicle is leaving the reference lane (10) or an exit is imminent, a correction yaw moment driver opposing the reference lane (10) is independently generated. To generate the corrective yaw moment, individual wheel torques are produced. In this case, to achieve a predefinable, desired reaction on the steering system of the vehicle (5), a desired torque distribution is determined and the wheel torques are set in accordance with the determined desired torque distribution.

Description

The The invention relates to a method for tracking according to the preamble of claim 1 and a lane keeping system according to the preamble of claim 10.

Such a method and such a lane keeping system are known from EP 1 298 021 A1 known. In this case, the current driving state of the vehicle is determined in a control unit and it is checked whether the vehicle has a tendency to deviate from a lane. If such a tendency is detected from the departure from the lane, drive or braking forces are determined for each vehicle wheel and according to the current driving state of the vehicle, so that a correction yawing moment is generated which serves to negotiate an agreement of the vehicle from the traffic lane to prevent. When determining the correction yaw moment, the steering angle or the steering angle change is taken into account.

outgoing from the next It is an object of the present prior art Invention a method for tracking or a lane keeping system with an improved steering reaction while the generation of the correction yaw moment to accomplish.

These The object is achieved by a method according to claim 1 and a lane keeping system according to the claim 10 solved. It can be a desired retroactive effect on the steering wheel of the vehicle during the driver independent Engagement, in which a correction yaw moment is generated, are specified. As desired retroactive effect on the steering wheel, for example, a desired steering angle or one with the desired steering angle correlated steering angle variable specified be that while the generation of the correction yaw moment should set. Alternatively or in addition to a desired Target steering angle can other steering angle variables, such as z. B. the steering angle speed, the Lenwinkelmoment or Steering angular acceleration can be specified.

Around this desired retroactive effect to achieve a desired torque distribution which specifies how the wheel torques must be adjusted to the desired, predetermined reaction to reach the steering system or on the steering wheel. This way you can while the generation of the correction yaw moment a defined, predetermined reaction be achieved on the steering system, so that an optimized vehicle behavior or a safe steering feel for the Driver results. Advantageous developments of the present invention arise from the dependent ones Claims.

The Target torque distribution can be the distribution of wheel torques between specify the front axle and the rear axle. It is possible that the desired torque distribution the desired Sum of the wheel torques at the front axle as the desired front axle torque and the desired one Sum of wheel torques at the rear axle indicates the desired rear axle torque. By a Decoupling it is possible in a simple way, both the leaving the target lane to provoke counteracting correction yaw moment as well as the desired retroactive effect to achieve the steering system or on the steering wheel.

The Target torque distribution and in particular the desired Vorderachsmoment is advantageously dependent from the desired steering angle and / or from the actual steering angle and / or from a Determined with the desired steering angle or the Istlenkwinkel correlated size. This will be the desired retroactive effect on the steering system by the desired steering angle or the Istlenkwinkel or one correlated with these sizes Size specified.

Thereby, that the desired torque distribution and in particular the desired Hinterachsmoment dependent on from the target yaw rate and / or the Istgierrate and / or one with the Sollgierrate or the Istgierrate correlated size is determined is ensured that not only the desired retroactive effect is achieved on the steering system, but also the necessary correction yaw moment is set so that can prevent the vehicle the target lane leaves, if this is possible due to the given physical limits.

Conveniently, be in the determination of the desired torque distribution and in particular the desired Vorderachsmoments and / or the Hinterachsmoments further predetermined vehicle parameters considered, which depend in particular on the respective vehicle type. Such vehicle parameters For example, the moment of inertia of the vehicle, the gauge of the vehicle, the wheelbase of the vehicle, Achkinematics - e.g. Steering wheel radius, caster, wheel lever arm - and more, the handling of the Vehicle characterizing sizes.

It is advantageous if the wheel torques for generating the correction yaw moment in addition to the wheel brake torque caused by a wheel-individual brake intervention is carried out by a wheel or axle-individual drive torque setting. The wheel torque required on a respective wheel of the vehicle is thus formed by a wheel braking torque and wheel drive torque. Accordingly, not only does a braking intervention take place in the respective wheel brake device, but at the same time the drive torque applied to this wheel is modified in order to achieve the required wheel torque.

One embodiment the method according to the invention or the lane keeping system according to the invention will be explained in more detail below with reference to the drawing. Show it:

1 a vehicle driving on a road in plan view,

2 an embodiment of a lane keeping system in a block diagram-like representation,

3 a schematic representation of forces acting on the vehicle forces and vehicle parameters and

4 An embodiment of a method according to the invention in the form of a flow chart.

1 shows a vehicle 5 that with a lane keeping system 6 Is provided. The lane keeping system 6 has lane departure detection means 7 for detecting the road ahead 8th in a detection area 12 , At the track detection means 7 they may, for example, be imaging sensor means, such as a camera. The from the Spurerfassungsmitteln 7 recorded road data become a computing device 9 transmitted from the detected lane course a target lane 10 calculated. This can be done, for example, by evaluating the road edges or lane markings 11 respectively.

The lane keeping system 6 furthermore has a vehicle sensor system 15 , the driving state data such as the actual yaw rate ψ., the actual steering angle δ _L , the vehicle longitudinal velocity v _x, the vehicle lateral velocity v _y, and the like to the computing device 9 transmitted. The computing device 9 may in the preferred embodiment of the lane keeping system 6 at 2 a brake control unit 16 of the brake system 17 , A the powertrain not shown drive the drive train control unit 18 and a steering controller 19 of the steering system 20 drive. About the computing device 9 Therefore, drivers can take independent action in the braking system 17 , the powertrain and the steering system 20 of the vehicle. Through the intervention in the drive train and the brake system 17 can the computing device 9 for every vehicle wheel 22 cause a wheel individual wheel torque, the one by the respective associated wheel brake 23 caused wheel braking torque and / or is formed by a caused by the drive train wheel individual or achsindividuell wheel drive torque.

The following is based on the in 4 flowchart shown an embodiment of the method according to the invention for tracking the vehicle 5 described.

In a first step 40 is about the Spurerfassungsmittel 7 of the lane keeping system 6 the roadway section ahead 8th recorded and in the arithmetic unit 9 a target lane 10 certainly. In the present embodiment, this is done by Bildverarbeitungsalgorhytmen that the course of the detected lane section 8th based on the roadway edge or the lane marking 11 determine. From the roadway and the width of the road can then be a target lane 10 be calculated. Such Bildverarbeitungsalgorhytmen are known per se, so that will not be discussed at this point. As an alternative to the illustrated embodiment could as a target lane 10 also the course of the roadside or the lane marking 11 be used.

In the next, second step 41 becomes the current direction of travel 42 of the vehicle 5 the computing device 9 based on sensor data of the vehicle sensor 15 certainly. The current direction of travel 42 can for example be calculated from the following driving condition data: On the one hand, the lateral deviation d between the current vehicle position 45 and the target lane 10 transverse to the direction of travel of the vehicle 5 seen and the Istgierwinkel ψ, the vehicle longitudinal axis 43 and the tangent to the target lane 10 in the direction of travel of the vehicle 5 seen at the height of the current vehicle position 45 to the target lane 10 is created. The direction of travel 42 therefore corresponds to the way the vehicle 5 while maintaining the current driving condition.

In the following third step 48 is in the computing device 9 checks whether between the determined direction of travel 42 and the determined target lane 10 there is a deviation from the ge it can be concluded that the vehicle 5 the roadway 8th leaves or leaving the lane 8th imminent. For this purpose, for example, a deviation threshold value can be predetermined, in which case when the deviation d exceeds the deviation threshold value, an exit or imminent departure from the roadway occurs 8th is closed.

Will be in the third step 48 found that the vehicle 5 the roadway 8th does not leave, or leave the lane 8th not before, so becomes the first step 40 jumped back.

Otherwise, in the third step 48 recognized that the vehicle 5 the roadway 8th leaves, or is expected to leave, the process in the fourth step 49 continued.

In the fourth step 49 Rad individual wheel torques are calculated to generate a correction yaw moment. The correction yaw moment acts on the vehicle 5 and is directed such that it reflects the tendency of the vehicle 5 the roadway 8th to counteract acts. In the situation in 1 is shown in the third step 48 be recognized that the vehicle will leave the lane on the right side. The correction yaw moment in this case would be counterclockwise directed to the vehicle 5 on the roadway 8th to keep.

The wheel moments at the individual vehicle wheels 22 so determined that a given, desired feedback on the steering system 20 he follows. To achieve this, the wheel torques at the individual vehicle wheels 22 determined according to a desired torque distribution. In the present exemplary embodiment, to determine the desired torque distribution, a desired front-axle torque M _V , which is the sum of the two wheel torques of the wheels of the front axle of the vehicle 5 is formed, and a target rear axle torque M _H , which is the sum of the two wheel torques of the wheels of the rear axle of the vehicle 5 is formed, calculated. The desired torque distribution thus indicates the distribution of the wheel torques between the front axle and rear axle of the vehicle.

d:

laterale Abweichung zwischen Referenz-Fahrspur und aktueller Fahrzeugposition

v_x:

Fahrzeuglängsgeschwindigkeit

v_y:

Fahrzeugquergeschwindigkeit

ψ:

Istgierwinkel

ψ .:

Istgierrate

k:

Kurvenkrümmung

Δψ:

Istgierwinkel bezüglich der Referenz-Fahrspur

The calculation is done as follows:
For the deviation between the current direction of travel 42 and the reference lane 10 In simplified terms, the following differential equations can be used: d. = ν x · Δψ + ν y Δψ. = ψ. - kv x With

d:

lateral deviation between reference lane and current vehicle position

_vx :

Vehicle longitudinal speed

v _y :

Vehicle lateral velocity

ψ:

Istgierwinkel

ψ .:

actual yaw rate

k:

curvature

Δψ:

Yaw angle with respect to the reference lane

mit

F_s,i:

Seitenkraft auf eines der Fahrzeugräder 22 (i = 1, 2, 3, 4)

F_u,i:

Umfangskraft auf eines der Fahrzeugräder 22 (i = 1, 2, 3, 4)

ψ ..:

Istgierbeschleunigung

ν ._y:

Zeitliche Änderung der Quergeschwindigkeit

ν ._x:

Zeitliche Änderung der Längsgeschwindigkeit

ΔM:

Giermoment aus auf das Fahrzeug einwirkender äußeren Querkraft (z.B. Seitemwind)

ΔF_s:

Auf das Fahrzeug einwirkende äußere Querkraft

ΔF_u:

Auf das Fahrzeug einwirkende äußere Längskraft (z.B. Hangabtriebskraft aufgrund einer Fahrbahnneigung)

m:

Fahrzeugmasse

s_v:

Spurweite des Fahrzeugs an der Vorderachse

s_h:

Spurweite des Fahrzeugs an der Hinterachse

l_v:

Abstand des Fahrzeugschwerpunkts SP von der Vorderachse des Fahrzeugs

l_H:

Abstand des Schwerpunkts SP des Fahrzeugs von der Hinterachse

For the driving dynamics of the vehicle 5 applies with reference to 3 following:

With

F _{s, i} :

Lateral force on one of the vehicle wheels 22 (i = 1, 2, 3, 4)

F _{u, i} :

Peripheral force on one of the vehicle wheels 22 (i = 1, 2, 3, 4)

ψ ..:

Istgierbeschleunigung

ν. _y :

Time change of the lateral velocity

ν. _x :

Time change of the longitudinal speed

.DELTA.M:

Yawing moment of external lateral force acting on the vehicle (eg side wind)

ΔF _s :

External lateral force acting on the vehicle

ΔF _u :

External longitudinal force acting on the vehicle (eg downhill force due to a road inclination)

m:

vehicle mass

s _v:

Gauge of the vehicle at the front axle

s _h :

Gauge of the vehicle at the rear axle

l _v:

Distance of the vehicle center of gravity SP from the front axle of the vehicle

l _H :

Distance of the center of gravity SP of the vehicle from the rear axle

mit

J_L:

Trägheitsmoments des Lenksystems

r_S,1:

Lenkrollradius links

n_K,1:

Nachlauf links

r_S,2:

Lenkrollradius rechts

n_K,2:

Nachlauf rechts

d_L, c_L:

Lenksystem abhängige Parameter

δv:

Istlenkwinkel an den lenkbaren Fahrzeugrädern

δH:

Lenkradistwinkel

i_L:

Lenkübersetzung

ΔM_L:

Lenkmoment

The following relationship applies to the steering dynamics of the vehicle:

With

J _L :

Inertia of the steering system

r _{S, 1} :

Steering wheel radius on the left

n _{K, 1} :

Caster left

r _{S, 2} :

Steering wheel radius right

n _{K, 2} :

Caster on the right

d _L , c _L :

Steering system dependent parameters

.DELTA.V:

Actual steering angle on the steerable vehicle wheels

delta H

Lenkradistwinkel

i _L :

steering ratio

ΔM _L :

steering torque

The circumferential forces F _{u, i} (i = 1-4) are set in accordance with the respective wheel torque acting on the wheel, which is formed in each case from a wheel braking torque and a wheel drive torque. The on the vehicle wheels 22 acting lateral forces F _{s, i} (i = 1-4) depend on the Istgierrate ψ., The lateral velocity v _y and the longitudinal velocity v _x . They counteract the build-up of a yawing moment.

ΔM*_G:

Giermomentstörgröße

ΔM*_L:

Lenkmomentstörgröße

From these equations, the desired Vorderachsmoment M _V and the target Hinterachsmoment M _H is now depending on the desired behavior of the steering system 20 determined. By combining forces and moments, the equations can be further simplified.

ΔM * _G :

Giermomentstörgröße

ΔM * _L :

Lenkmomentstörgröße

From this, the equations for the desired Vorderachsmoment M _V and the desired Hinterachsmoment M _H can now be determined:

δ .._{v, Soll}:

Solllenkwinkelbeschleunigung

δ ._{v, Soll}:

Solllenkwinkelgeschwindigkeit

δ_{v, Soll}:

Solllenkwinkel

ψ .._Soll:

Sollgierbeschleunigung

ψ ._Soll:

Sollgierrate

q_0:

Reglerverstärkungsfaktor

q_1:

Reglerverstärkungsfaktor

With:

δ .. _{v, target} :

Target steering angular acceleration

δ. _{v, should} :

Target steering angular velocity

δ _{v, should} :

Target steering angle

ψ .. _target :

Target yaw acceleration

ψ. _Should :

Target yaw rate

q _0:

Controller gain

q _1:

Controller gain

Are the Radumfangskräfte - ie the individual wheel torques - the Istgierrate ψ. and the Istlenkwinkel δ _v known, the yaw momentum disturbance size .DELTA.M * _G and the Lenkmomentstörgröße .DELTA.M * _L can be determined using a Störgrößenbeobachter and can then be compensated in a known manner by switching in a controller.

As an alternative to a disturbance observer, a state controller, in particular a so-called Riccati controller (in which a quadratic quality criterion is optimized) can be used to set the desired Vorderachsmoment M _V and the desired Hinterachsmoment M _H according to the target specifications. It is possible to weight the steering and yaw behavior of the vehicle to different degrees and to take into account the steering dynamics of the vehicle in the controller. In this way, interventions in the steering and in the drive train of the vehicle, such as. B. in the engine, in the transmission or in the Achsedifferenziale be realized.

Have been the desired Vorderachsmoment M _V and the target Hinterachsmoment M _H in step 49 determined, will in the next step 50 on every vehicle wheel 22 set a wheel torque, such that the target Vorderachsmoment M _V and the desired Hinterachsmoment M _H result. The procedure will follow the fifth step 50 again at the first step 40 started.

Claims (9)

A method of tracking for a vehicle, wherein the reference lane is determined and compared with the current heading course, wherein a departure from the reference lane counteracting correction yaw moment driver is generated independently when the comparison result indicates that the vehicle is the reference lane leaving or leaving is imminent, and wherein for generating the correction yaw moment Rad individual wheel torques are generated, characterized in that to achieve a predetermined, desired reaction on the steering system of the vehicle, a desired torque distribution is determined, and the wheel torques are set in accordance with the determined target torque distribution. The method of claim 1; characterized, that the desired torque distribution the distribution of the wheel torques between indicates the front axle and the rear axle of the vehicle. A method according to claim 1 or 2, characterized in that the desired torque distribution the desired sum of the wheel torques on the front axle as the desired front axle torque and the desired sum indicates the wheel torque at the rear axle as a target Hinterachsmoment. Method according to claim 3, characterized that the desired Hinterachsmoment depending on the target Vorderachsmoment is determined. Method according to one of claims 1 to 4, characterized that the desired torque distribution and in particular the desired Vorderachsmoment dependent on from the desired steering angle and / or from the actual steering angle and / or from a Determined with the desired steering angle or the Istlenkwinkel correlated size becomes. Method according to one of claims 1 to 5, characterized that the desired torque distribution and in particular the desired Hinterachsmoment dependent on from the desired yaw rate and / or the actual yaw rate and / or from a determined with the Sollgierrate or the Istgierrate correlated size becomes. Method according to one of claims 1 to 6, characterized that the desired torque distribution and in particular the desired Vorderachsmoment and / or the desired Hinterachsmoment depending on predetermined vehicle parameters be determined. Method according to one of claims 1 to 7, characterized that the wheel torques for generating the correction yaw moment in addition to by a wheel individual braking intervention caused by wheel braking a wheel or axle-individual drive torque adjustment takes place. Lane keeping system for a vehicle with track detection means for detecting the preceding ones Roadway, with a computing device coming out of the detected roadway determines a reference lane and the current direction of travel with the reference lane wherein the computing means yaw moment generator means for generating a departure from the reference lane counteracting Correction yaw moment driver independently triggers when the comparison result indicates that the vehicle is leaving the reference lane, or a departure is imminent, and wherein the yaw moment generating means Rad generate individual wheel torques, characterized in that a Target torque distribution is determined, which is to achieve a specifiable, desired retroactive effect on the steering wheel of the vehicle during the Generation of the correction yaw moment is used, wherein the wheel torques according to the determined Setpoint torque distribution can be set.