WO2004083014A1

WO2004083014A1 - System for automotive assisted-steering tracking system

Info

Publication number: WO2004083014A1
Application number: PCT/EP2004/000843
Authority: WO
Inventors: Hans Fritz
Original assignee: Daimlerchrysler Ag
Priority date: 2003-03-20
Filing date: 2004-01-30
Publication date: 2004-09-30
Also published as: DE10312513A1; DE10312513B4

Abstract

The invention relates to a system (100) for an automotive assisted-steering tracking system. In said system, the vehicle position with respect to a track is determined with the aid of a position detecting device and is used for determining a specified deflection angle by a track controller in order to define a specified deflection moment which is used at a moment of a steering deflection which is generated by a driver and transmitted to a steering device (4) which actuates steering wheels. Said track controller (11) is connected to a separate computing unit (12) carrying out a function which is opposite to a deflection actuator which determines the specified deflection moment on the base of the specified deflection angle of the track controller.

Description

System for lane steering support in a vehicle

The invention relates to a system for lane-keeping steering support in a vehicle according to the preamble of claim 1.

Such a system is described in EP 1 170 651 A2. In the lane-keeping steering support system, the position of the vehicle relative to the lane is determined with the aid of a position detection device and the determination of a target steering angle is used, from which the current for an electric motor to be controlled is determined, via which the desired target steering angle is set in the steering device. In the lane-keeping steering support system, two ^" control loops connected in series ^" are used, the target steering angle being determined from the first control loop, from which the current for the electric motor to be controlled is determined in the second control loop.

The disadvantage here is that non-linearities resulting from the steering actuator system are not taken into account in the control loops. The double regulation also requires considerable effort in the implementation of the lane-keeping support. The invention is based on the problem of creating a system for lane-keeping steering support in a vehicle, which is characterized by a high degree of variability with relatively little effort. Non-linearities of the steering device should also be taken into account expediently.

This problem is solved according to the invention with the features of claim 1. The subclaims indicate appropriate further training.

In the lane control system according to the invention, the position of the vehicle in relation to the lane is determined with the aid of a position detection device and the basis for determining a target steering angle in a lane controller. A target steering torque is generated from the target steering angle and is to be supplied to a steering device for setting the actual steering angle. The target steering torque can be superimposed on the driver steering torque generated by the driver.

The system comprises a lane controller and a separately designed and decoupled calculation unit downstream of the lane controller, in which an inverse steering actuator function is implemented, from which the target steering torque to be supplied to the steering device is determined from the target steering angle of the lane controller. The decoupling of the lane controller and the downstream calculation unit with the inverse steering actuator function offers the advantage that the properties of the steering actuator system do not have to be taken into account in the lane controller design. In this way, standardized lane regulators can be used, each of which is followed by a vehicle-dependent calculation unit that contains the inverse steering actuator function. Among other things, this procedure offers the possibility of to combine lane control with the same, downstream calculation unit or, conversely, to combine a common controller type with different, downstream calculation units. Overall, the design effort for a large number of different lane control systems is reduced.

Another advantage can be seen in the fact that non-linearities in the steering actuator system can be compensated for by the inverse steering actuator function. This significantly improves tracking. A second subordinate regulation can also be dispensed with.

The inverse steering actuator function in the downstream calculation unit follows a known relationship from which the target steering torque is determined as a function of the target steering angle supplied by the upstream lane controller. The relationship of the target steering torque as a function of the target steering angle can be either a mathematical, functional relationship or a stored map.

In the case of a mathematical relationship, both a static component in the inverse steering actuator function, which is to be determined as a function of the target steering angle, and a dynamic component as a function of the first and / or the second derivative of the target steering angle can be taken into account. In the dynamic components, in particular the mass inertia of the steering device acting on the steerable wheels and a damping component in the steering device can be taken into account.

In the case of a stored map, this can be determined from measurements during test drives of a real vehicle. those in which the actual steering angle that is established at a given steering torque is determined as the stationary operating points.

Further advantages and expedient designs can be found in the further claims, the description of the figures and the drawings. Show it:

1 is a schematic block diagram of a system for lane control of a vehicle, with the aid of which the tracking of a motor vehicle on a roadway can be supported and which comprises a lane controller and a further calculation unit separately formed by the lane controller with an inverse steering actuator function,

2 is a block diagram with a detailed representation of the downstream calculation unit with the inverse steering actuator function,

Fig. 3 is a schematic block diagram of an operating device for the lane control system.

In the figures, the same structural units are provided with the same reference symbols.

The lane control system designated by reference numeral 100 in FIG. 1 serves to support the driver in keeping a motor vehicle in lane along a predetermined lane by adding a desired steering torque to the steering torque applied by the driver and feeding it to a steering device. The lane control system 100 comprises a position detection device 1, a target lane sensor 2, a sensor 3 for detecting the current driving state and one Lane support control device 10, in which the desired steering torque is generated and then fed to the superimposed steering device 4.

The lane information and position information of the vehicle relative to the lane or lane determined by the position detection device 1 include, in particular, the lateral offset Δy to the lane edge, the yaw angle Δψ of the vehicle relative to the lane and the lane curvature C. These data are signaled as input variables by the position detection device 1 passed to the lane support control device 10.

Furthermore, the lane support control device 10 is supplied as input variables with data from the target lane sensor 2 about the lateral target offset Δy _{so to be} observed, relative to the roadway. Information z about the current driving state of the vehicle is also passed as input variables from the driving state detection sensor system 3 to the lane support control device 10. The information z from the sensor system 3 about the current driving state or vehicle operating state comprises at least one or more of the variables steering wheel angle, yaw rate, transverse speed, lateral acceleration and in particular the driving speed v.

The lane support control device 10 is constructed in three stages and comprises a lane controller 11, a calculation unit 12 connected downstream of the lane controller with an inverse steering actuator function and, as a further, downstream stage, a limiter 13. A suitable lane control algorithm is stored in the first stage, the lane controller 11. The signals or information from the position detection device 1, the target Via 2 and the driving state detection sensor system 3, which are processed in the lane control algorithm and from which a controller-internal target _{wheel steering} angle δ _{wheel is} generated as an output variable, which is supplied as an input variable to the downstream calculation unit 12.

The calculation unit 12 determines from the target wheel steering angle δ _{Rad so} ii and taking into account the driving state information z supplied to it by the sensor system 3 in accordance with an inverse steering actuator function stored in the calculation unit 12 as a target quantity a target steering torque M _Lenk . The

Target steering torque M _{is to steering} is subsequently supplied as an input variable to the limiter 13, in which the target steering torque to a predetermined, maximum permissible value ^ _{srf /} is limited. This maximum value M_ ^. _tt is finally fed to the superimposed steering device 4, in which the maximum value M__ _soU for the target steering torque is additionally _superimposed on the driver steering torque M _{steering driver} , which it specifies via the steering wheel 5, and used to adjust the actual wheel steering angle to maintain the desired lane becomes.

The steering torque M _{Le als driver} applied by the driver via the steering wheel and the steering wheel angular speed δ _{steering driver} generated by the driver on the steering wheel are supplied to the limiter 13 as additional input signals. These additional

Input signals enable the lane-keeping steering assistance to be switched off by rapid steering movements by the driver and / or by the driver specifying large steering torques. For this purpose, for example, the steering torque M__ _n given by the lane support control device 10 can be speed of the steering torque applied by the driver via the steering wheel M- _{steering driver} and / or the applied steering wheel angular speed δ _{steering driver} are limited to the value zero.

2 shows a detailed illustration of the calculation unit 12 with the inverse steering actuator function. Based on this Lenkaktuatorfunktion forms the connection between the predetermined on the steering wheel steering torque M _steering and which Ü over the steering gear of the steered wheels of the vehicle adjusting wheel steering angle δ _wheel according to the relationship

where F _{Lenk is} a known, functional connection. The torque balance on the steering wheel or on the steering wheel input of the steering gear results in:

JψL nk ⁼ ^ Lenk ~ ^ Lenk, Last ~ ^■ "* Lenk.D

the relationship between the Radlenkwinkelbeschleunigung i _enk ^{un (^} the ^au f the steering wheel or the steering gear acting moments. M _steering is herein represents the predetermined on the steering wheel steering torque, M _{Lenk> load} the restoring acting on the steering wheel or load torque, which due to the lateral force S _wheel acts on the steered wheels - in particular the front wheels - and M _{steering D} the damping torque acting on the steering _wheel side in the steering system, with J the moment of inertia of the steering system. The mathematical integration twice provides the steering wheel angle φ _steering ^a -L ^s function of the specified actuating or steering torque:

EiLeiik ~ F Lenk

) ^•

The Lenkaktuatorfunktion, which describes the relationship between the predetermined on the steering wheel steering torque M _steering and the steering angle δ _wheel of the steered wheel, with the can in the

Steering gear existing steering ratio i _L according to the relationship

'Wheel F _L enk ( ^M Lenk) = Ψ. steering

)

to be discribed. The inverse steering actuator function can be performed on the level of the target variables as a function of the target wheel steering angle δ _{Rad soli} according to the relationship

- * ™ steering, should ⁼ ^ steering \ ° wheel, should) ⁼ ^ steering, should \ ° wheel, should) ^" * ^" ^ steering.soll ° wheel, should> ° ^' wheel, should)

_to or generally as a function δ of a target steering angle in accordance with

- ^ Lenk, should ⁼ ^ Lenk \ ° _S oll) ~ "^ Lenk, should ° _S oll) + -" * Lenk, should ° 'should'"should)

Describe, where in addition to the steering angle at the location level, the respective speed and acceleration value are used.

2 shows in detail the various units which are part of the calculation unit 12 with the inverse steering actuator function. The calculation unit 12 is used as a gear size the desired wheel steering angle δ _{wheel should be} supplied. The calculation unit comprises two subsystems: on the one hand a subsystem 20 with static components of the inverse steering actuator function, on the other hand a subsystem 30 with dynamic components of the inverse steering actuator function. The target wheel steering angle δ _wheel target _is supplied to both subsystems 20 and 30 as an input variable. The subsystem 20 for calculating the static components provides the static component M _L ^s _k target of the target steering torque as an output variable; In a corresponding manner, a dynamic component M _L ^dy _n " _k target of the target steering torque is calculated in the subsystem 30. The two components M ^s _{nk soü} and M _ek target from the subsystems 20 and 30 are then added and as a common target steering torque M. _{Lenk is to be} fed _to the following calculation unit - the limiter 13 from FIG. 1.

The subsystem 20 for calculating the static proportions of the target steering torque comprises a first unit 21, in which a model for determining the target restoring torque or target load torque is stored. The unit 21 delivers as an output variable an input to the steering linkage

Steering gear related target torque M _R ^ _dl , which is fed as an input variable to the subsequent unit 22, in which an inverse model of the steering gear is stored.

In unit 22, the target torque M _R ^s ^ _{d sol!} the static target steering torque M _L ^st _nk referred to the steering wheel _is calculated.

According to a simple embodiment of an inverse model of the steering gear on which the unit 22 is based, the static component ^ _{so //} as a function of the desired torque - ^ _a ! Ι _so ii according to the relationship M ^lvl Len ^t k, shall ^m MR ^st a ^a d ^t .soll i _L K _L

determined, with K _L the steering gain of the steering gear and i _L the steering ratio is designated.

In the unit 21, taking into account the information z about the current driving state, which is provided by the sensor system 3 (FIG. 1), and the target wheel steering angle δ _{Sad u} with the input variable driving speed v, the target torque M _R ^s _ad target according to relationship

^IVI wheel, should ~ "r wheel, should

determined as a function of the tire wake n _r and the wheel lateral force S _{Rad son} . The wheel side force S _RadtS0ll is a function of the target _slip angle. Simplified, this lateral force or the desired oblique angle can be linearized as a function of the desired wheel steering angle δ _{wheel oll}

In this respect, C _{Ra (i} denotes the lateral stiffness of the wheels, which is known from tire characteristics, l _wheel the distance between the center of gravity of the vehicle and the wheel axis with the steered wheels, K _ß the stationary angle of attack gain and K _ψ the stationary yaw rate gain dependent on the speed v. The subsystem 30 with the dynamic components of the inverse steering actuator function comprises in particular a differentiating unit 31, which is supplied as the input variable to the target wheel steering angle δ _{Rad so} ii and which, as the output variable, provides the target wheel steering angle speed δ _Rad and the target as a first and second time derivative -

_Wheel steering angle acceleration δ _{wheel should} deliver. In an advantageous embodiment, the differentiating unit 31 contains a state variable filter which, in comparison to the numerical differentiation, supplies a smoother signal curve for the differentiated signals.

The target _wheel steering angle acceleration δ _wheel target is fed _to a downstream unit 32 as an input variable in which a model for determining the inertia-related target steering torque is stored. In unit 32, the

Input variable δ _{Rad soü} according to the relationship

J

M Lenk.T.soll 'wheel, should

the dynamic component M _steering, τ _{, which} takes into account the moment of inertia J of the steering device _{, thus} determines the target steering torque. Parallel to the unit 32, another unit 33, in which a model for determining the damping-related target steering torque is stored, as a function of the target

_Wheel steering angular velocity δ _{wheel shall be} according to the relationship

D _L

M Lenk, D, should ~. _T r ° wheel, should K _L the dynamic component M _{steering, D} taking into account the damping component _and calculated the target steering torque. D _L here denotes the damping constant of the steering.

The dynamic torque components determined from the units 32 and 33 are in accordance with the relationship

M dyn Lenk, oll = M Lenk, T, should + M Lenk, D, should

added to the dynamic component M _L ^dy _{e ktSOll of} the target steering torque.

Then the dynamic and the static part according to the relationship

the resulting target steering torque M _{steering is} calculated,

The limiter unit 13 enables the lane steering support to be switched off independently. This can be done, for example, by rapid steering movements by the driver and / or by the driver specifying large steering torques.

3 shows a schematic block diagram of an exemplary embodiment of an operating device for the lane control system 100 according to the invention, with an operating unit 50 assigned to the lane control system, and a display unit 54. The operating unit 50 (for example a multifunction steering wheel) has operating elements 50a, 50b for activation or deactivation of the lane control system. An alternative control element 51 for activating or deactivating the lane control system is also shown. The driver generates an activation signal S _AKT or a deactivation signal S _DEA κτ for activating or deactivating the lane control system via the control elements 50a and 50b designed as two buttons of a multifunction steering wheel. This operating function can alternatively be implemented with a single operating lever 51 with opposite operating directions for the activation or deactivation of the lane control system. When the lane control system is activated, the lane-keeping steering support can be canceled (deactivated) at any time by operating the control lever in the opposite direction or by pressing the opposite control button.

Alternatively, an emergency switch (not shown) which is conveniently placed and can be actuated by the driver in an emergency can also be provided. When the emergency switch is actuated, the lane-keeping system is immediately stopped and the driver regains full control of the vehicle. In this emergency, the steering device, the drive device and the braking device can be operated by the driver in the usual way. The emergency switch function can also be coupled, for example, to the brake or accelerator pedal, so that the lane keeping joint support is interrupted by the driver in the event of sudden braking or accelerating.

The degree of lane-keeping steering support can also be set by the driver via the operating unit 50. For this purpose, a signal S _UG generated by the driver is transmitted to the lane control system 100 via an operating element, for example a rotary knob, the signal S _{UG being able to assume} a value between 0% and 100% and the degree of lane-keeping steering support being set to a corresponding extent.

For example, the maximum value M ^ _{J (III} for the target Steering torque M _{steering is to be} influenced by the driver in the limiter within predetermined limits.

The display unit 54 shows the driver the entire system and whether or not the lane-keeping steering support is activated. The ready state is transmitted to the display unit 54 with the signal S _BZ . The display unit 54 contains a display element 54a, which shows the driver the current system status including the currently set degree of lane-keeping steering support.

Claims

claims

1. System for lane-keeping steering support in a vehicle, in which the position of the vehicle relative to the lane is determined by means of a position detection device (1) and the

Determining a target steering angle (δ _soll) is used as a basis in a lane controller (11), from which a target steering torque (^ ^_'steering is _so ii determines ^ that is superposed on a signal generated by the driver driver steering torque (M _{Lenlc Fahm.)} and a steering device (4) acting on the steerable wheels is fed, characterized in that the lane control (11) is followed by a separately designed calculation unit (12), in which according to an inverse steering actuator function (F_ ^ _nk ) from the target steering angle (δ _should ) of the lane controller (11) the target steering torque (M _{steering l} ) is determined, the inverse steering actuator function (F ^ _nk ) determining the target steering torque {M _{steering target} ) according to the relationship

M- steering, target ⁼ ^ steering ° target)

is taken as a basis, whereby

^ Steering _{, o} iι the target steering torque, δ _is the target steering angle,

F ^ _nk denote the inverse, known steering actuator function.

2. System according to claim 1, characterized in that the inverse steering actuator function (F ^~ ^ _nk ) as the inverse

Behavior of the steering actuator descriptive, mathematical replacement model is realized.

3. System according to claim 2, characterized in that from the inverse steering actuator function (F _L ^~ _nk ) to be determined target steering torque (M _steering target) a static component {M ^s "/ _lktSθU ) and a dynamic component {M _L ^d _ύtSθll ) includes:

M to steering, steering ^~ ^ ° 'oll) ⁼ M Lenk, should ° _so u) + -M- steering setpoint ( "heck ° oll)'

4. System according to claim 3, characterized in that the dynamic component of the setpoint steering torque (M _LaΛsoll) takes into account the moment of inertia (J) of the steering device (4) and the target steering angle acceleration (δ _soll).

5. System according to claim 3 or 4, characterized in that the dynamic component (Mζ _n " _ksoll ) of the target steering torque (M _LenktSott ) a damping _component (D _L ) in the steering device

(4) and the target steering _{angular velocity} (δ _soIl ) is taken into account.

6. System according to claim 4 and 5, so that the dynamic components which take into account the moment of inertia and the damping component are additively superimposed.

7. System according to any one of claims 1 to 6, characterized in that the inverse steering actuator function (F _L ^~ ^ _nk ) is present as a map in the downstream calculation unit (12).

8. System according to claim 7, so that the map is determined from measurements on a real vehicle.

9. System according to any one of claims 1 to 8, characterized in that the calculation unit (12) with the inverse steering actuator function {Fl _nk ) is followed by a limiter (13) in which the target steering torque (M _steering> target) to a maximum value ( ^M _{nk, so} iι) is limited.

10. System according to one of claims 1 to 9, d a d u r c h g e k e n n z e i c h n e t that the degree of lane-keeping steering support is adjustable by the driver.

11. System according to claim 9 and 10, characterized in that the maximum value (M ™ _ksoll ) for the target steering torque (M _Lenksoll ) in the limiter (13) can be influenced by the driver within predetermined limits.

12. System according to one of claims 1 to 11, d a d u r c h g e k e n n e e c h n e t that the system is designed to be switched on and off.

13. System according to claim 12, so that the system can be activated and deactivated manually by the driver.

14. The system according to claim 12 or 13, so that the system is deactivated in that a variable describing the driving state exceeds a limit value.

15. System according to one of claims 1 to 14, so that the system is deactivated if a steering angle speed generated by the driver exceeds a limit value.

16. The system according to claim 1, wherein the system is deactivated if a steering torque applied by the driver exceeds a limit value.

17. System according to one of claims 1 to 16, characterized in that a display device for displaying the current system status including the display of the current set degree of lane-keeping support is provided.

18. System according to any one of claims 1 to 17, characterized in that _(should δ) as a target steering angle of the target wheel steering angle (δ _RadsoU) is used.