DE102016210126B4 - Method for controlling a vehicle and vehicle for implementing the method - Google Patents

Abstract

Method for controlling a vehicle (1),
wherein the vehicle (1) has at least one steered axle (2) with driven wheels (3), the driven wheels (3) being driven via a wheel-selective drive (4),
wherein the vehicle (1) has a steering system (5) with a steering force device (10),
wherein the vehicle (1) has a first steering force module (11) for controlling the steering force device (10) and a second steering force module (12) for controlling the wheel-selective drive (4),
marked by
an actuator module (13) for controlling the first and second steering force modules (11, 12), these being controlled so that an intermediate section (15) of the steering system (5) between the steering force device (10) and the driven wheels (3) is elastic is tensioned, the actuator module (13) forming a control device for the strength of the elastic tension as a manipulated variable.

Description

The invention relates to a method for controlling a vehicle with the features of claim 1. Furthermore, the invention relates to a vehicle for implementing the method with the features of claim 10.

Wheel-selective traction drives enable the transverse dynamics of the vehicle to be influenced by specifically distributing the drive power to individual wheels by varying primarily longitudinally dynamic variables. Through the use of wheel-selective traction drives on the steered axle of a vehicle, the wheels can be turned through a targeted setting of differences in drive power.

In the pamphlet DE 10 2009 025 058 A1 A motor vehicle is disclosed which comprises a vehicle steering system with a mechanically determined steering ratio and at least one device for distributing a drive torque to the wheels of a driven vehicle axle according to a predeterminable distribution setpoint. Furthermore, a control unit is provided which, in the linear range of the lateral dynamics, in which a normal driver usually moves, determines the distribution setpoint as a function of signals from sensors located on the vehicle and algorithms stored in the control unit in such a way that a yaw moment generated via the vehicle steering is triggered by at least one Device for distributing a drive torque generated additional yaw moment is superimposed. This allows the effect of a direct, indirect or variable steering ratio to be achieved.

In the pamphlet DE 10 2007 043 599 A1 In a method for carrying out a steering process in a vehicle, the driver specifies a steering angle which is converted into a wheel steering angle via a steering system. A torque distribution between at least one left and one right vehicle wheel is carried out by means of an additional actuator. A variable steering ratio is implemented via the torque distribution, in that an additional steering angle is superimposed on the steering angle specified by the driver via the steering effect of the additional actuator on the vehicle movement.

In the pamphlet DE 10 2008 001 136 A1 a method for actuating a steering actuator in a vehicle with an adjustable clutch is presented, which enables a variable distribution of the drive torque between a left and a right wheel. According to the publication, the steering actuator is regulated as a function of the clutch setting in such a way that a torque which is caused by a change in the torque distribution and which acts on the steering is at least partially compensated for.

The DE 10 2006 026 863 A1 describes an independent suspension for a steerable wheel, the wheel being connected to a wheel carrier designed as a swivel bearing and a steering lever being firmly connected to the wheel carrier on the one hand and articulated to a tie rod on the other.

It is the object of the present invention to propose a method and a vehicle with the method which enable improved steering behavior in the vehicle. This object is achieved by the method having the features of claim 1 and by a vehicle having the features of claim 10. Preferred or advantageous embodiments emerge from the subclaims, the following description and the attached figures.

The invention relates to a method for controlling a vehicle. The vehicle has at least or precisely one steered axle with driven wheels. The steered axle is preferably designed as a front axle. The vehicle has a steering system for steering the steered and driven axle. The steering system preferably has a steering wheel or another human-machine interface for inputting a steering command, a steering column, a steering gear, the steering gear being operatively connected to wheel carriers via tie rods as part of the steering system.

Steering the vehicle via the steering system enables the driver to influence the lateral dynamics of the vehicle and thus steer the vehicle in the desired direction. The driver's request is transferred to the steering system by turning the steering wheel or the man-machine interface to input a steering command in the form of the steering wheel angle phi _H , the driver having to apply a steering torque (M _H ).

The vehicle has a steering force device, in particular a steering force assistance device (LKU), and a first steering force module for controlling the steering force device. The steering force module can be designed as a software module, a hardware module or a combination thereof.

In the vehicle with the steering force device, the steering torque is reduced by an actuator in order to enable the driver to steer comfortably. For example, it is provided that the steering column transmits the movement to the steering gear. There the rotative movement of the steering column turns into a translational movement of the tie rods transferred. These transmit the movement to the wheel carriers, which rotate (steering angle phi) around the respective steering axis.

genannt. Sie bestimmt zum einen den notwendigen Lenkradwinkel, der für einen gewissen Einschlag der Räder erforderlich ist, zum anderen beeinflusst sie aber auch, wie stark die an den Rädern anliegenden Kräfte auf das Lenkrad übertragen werden. Bei eingeschlagener Lenkung eines fahrenden Fahrzeuges bauen sich am Reifen-Fahrbahn-Kontakt Kräfte auf, die die Querbewegung des Fahrzeuges beeinflussen. Die Summe der am Rad angreifenden Querkräfte wirkt in Form einer Seitenkraft und zusammen mit den Längskräften als Giermoment (Moment um die Hochachse) auf den Fahrzeugaufbau, wodurch eine Drehung des Fahrzeuges um die Hochachse ermöglicht wird.The transmission ratio between the steering wheel angle and the steering angle of the wheels is called the kinematic steering ratio $${\text{i}}_s=\frac{{\mathrm{\phi }}_{\text{H}}}{\mathrm{\phi }}$$

called. On the one hand, it determines the steering wheel angle required for a certain turning angle of the wheels, but on the other hand it also influences how strongly the forces applied to the wheels are transmitted to the steering wheel. When the steering of a moving vehicle is turned, forces build up at the tire-road contact, which influence the transverse movement of the vehicle. The sum of the transverse forces acting on the wheel acts in the form of a lateral force and together with the longitudinal forces as a yaw moment (moment around the vertical axis) on the vehicle body, which enables the vehicle to rotate around the vertical axis.

In the following, the forces acting on the tire-road contact and generating the steering wheel torque via wheel carriers, tie rods and steering gears are considered. The forces and their points of application on the wheel are taken as given here. For a more detailed consideration of the force build-up at the tire contact area, reference is made to the literature.

In the 1 a left front wheel with selected suspension points and components of the chassis are shown schematically, as well as the forces acting on the tire contact area (contact patch). The forces can be broken down into the components F _{W, X} (drive or braking force), F _{W, Y} (lateral force) and F _{W, Z} (wheel load). With the resulting lever arms around the steering axis (axis between points E and G), a resulting moment is obtained for each force vector. The sum of these moments (both wheels) results in the steering moment.

In conventional drive concepts in which the drive torques on both wheels are the same, according to Pfeffer & Harrer, 2013, for example, the lateral force F _{W, Y has} the greatest influence on the steering torque. The restoring effect due to the wheel load Fw, z, on the other hand, is small (especially when cornering at high speed) and is not considered further here. The decisive factor for the implemented concept of steering force assistance is the effect of the drive or braking force Fw, x on the steering torque. The following therefore looks at how the steering torque _{can be calculated from the two components F W, Y} and Fw, x.

Like in the 1 shown, the force Fw, x acts at point W and is perpendicular to the YZ plane. In order to determine the influence on the torque around the steering axis, it is assumed that the drive torque is supported in the vehicle body (and not in the wheel carrier) and is transmitted to the wheel axis via a cardan shaft. This is the case with preferably used internal drives, which include the conventional drive trains and the drives close to the wheels. Since the wheel can only transfer forces to the wheel carrier in the wheel bearing, the force Fw, x is shifted to the center of the wheel to calculate the moment. The disturbing force _{lever arm r a} , which is perpendicular to the steering axis, thus represents the effective lever arm with which the force Fw, x generates a moment about the steering axis.

Die Seitenkraft F_W,Y greift nicht im Punkt W, sondern in einem um den Reifennachlauf r_τ,T verschobenen Punkt. Daraus ergibt sich folgender Zusammenhang für die von der Seitenkraft induzierte Komponente des Lenkmoments Ms: $$M_S\approx F_{W,y}\cdot \left(r_{\tau ,k}+r_{\tau ,T}\right)$$

Beim Konzept einer Lenkkraftunterstützung mittels radselektiver Antriebe wird das Lenkradmoment dadurch reduziert, dass das Antriebsmoment in geeigneter Weise auf die beiden Räder der gelenkten Achse verteilt wird. Bei der folgenden Herleitung wird zum Zwecke einer anschaulicheren Betrachtung davon ausgegangen, dass der Spreizungswinkel und der Nachlaufwinkel 0° betragen, die Nachlaufstrecke r_τ und die Lenkübersetzung i_s konstant sind und der Lenkwinkel beider Räder identisch ist.In the following, small spread and caster angles are assumed as a model. This results in the following relationships between the drive or braking force Fw, x and the associated components of the steering torque MA, a / b. $${\mathrm{M.}}_{\mathrm{A.},a}\approx {\mathrm{F.}}_{\mathrm{W.},X}\cdot r_a$$

The lateral force F _{W, Y} does not take effect at point W, but rather at a point shifted _{by the tire trail r τ, T.} This results in the following relationship for the component of the steering torque Ms induced by the side force: $${\mathrm{M.}}_{\mathrm{S.}}\approx {\mathrm{F.}}_{\mathrm{W.},y}\cdot \left(r_{\tau ,k}+r_{\tau ,T}\right)$$

In the concept of steering power assistance by means of wheel-selective drives, the steering wheel torque is reduced in that the drive torque is appropriately distributed to the two wheels of the steered axle. In the following derivation, it is assumed for the purpose of a clearer consideration that the spread angle and the caster angle are 0 °, the caster distance r _τ and the steering ratio i _{s are} constant and the steering angle of both wheels is identical.

When driving through a left curve, the in 2 Forces shown on the left on the steering system. The drive torque is distributed evenly to both wheels, so that the drive force F _{A, l} = F _{A, r} is applied to each wheel. When cornering, the lateral forces F _{S, l} and F _{S, r} build up. The following conditions are obtained for the steering wheel torque: $$\begin{array}{c}{\mathrm{M.}}_H=\frac{1}{i_s}\left[r_{\tau }\cdot \left({\mathrm{F.}}_{s,l}+{\mathrm{F.}}_{s,r}\right)+\underset{=0}{\underbrace{r_a\left({\mathrm{F.}}_{\mathrm{A.},l}-{\mathrm{F.}}_{\mathrm{A.},r}\right)}}\right]\\ \text{at the same}\underset{<0}{\underbrace{\text{distributed A}}}\text{drive torque}\\ \text{when shifting the drive torque to the right wheel}\end{array}$$

The two side forces each contribute to the total torque with the same sign, whereas the driving forces have a positive and a negative component
surrender. If the driving forces are evenly distributed, their effects cancel each other out. This is where the concept of power steering by means of wheel-selective drives comes in. By shifting the drive torque to the wheel on the outside of the curve ( 2 , right) the two driving forces generate a moment around the steering axis, which counteracts the moment of the side force.

The redistribution of the drive torque also has an influence on the vehicle's lateral dynamics, since the two force vectors F _{A, l} and F _{A, r} contribute to the yaw moment (moment around the vehicle's z-axis) (see torque vectoring).

Torque vectoring refers to a method in which the drive torque distribution of a vehicle can be specified variably at each wheel in order to optimize the vehicle behavior according to the driving situation. In conventional drives with combustion engines, this is implemented either via two controllable clutches or via a superposition gear (axle transfer gear).

• • Agilitätssteigerung (zusätzliches Giermoment zur Verbesserung des Einlenkverhaltens)
• • Gierdämpfung (stabilisierendes Giermoment, der Gierrate entgegengesetzt)
• • Erhöhung der Fahrsicherheit
• • Verbesserung des Komforts

In the vehicle according to the invention with a wheel-selective drive, in particular with electric drives for individual wheels, torque vectoring can be implemented by controlling the individual wheel drives. To control the wheel-selective drive, the vehicle has a second steering force module. The second steering force module can be constructed in the same variants as the first steering force module. The driving dynamics, in particular the yaw moment, are influenced by torque vectoring, which optionally results in the following applications:

• • Increase in agility (additional yaw moment to improve steering behavior)
• • Yaw damping (stabilizing yaw moment, opposite to yaw rate)
• • Increase in driving safety
• • Improving comfort

Another effect of torque vectoring is the possible reduction in the steering angle requirement depending on the lateral acceleration. In addition to torque vectoring, the "Electronic Stability Program" (ESP) is another option for vehicle dynamics control. With ESP, however, the yaw moment is only influenced by braking individual wheels. Torque vectoring can therefore be seen as an extension of the vehicle dynamics control for the drive state.

In the case of steering assistance by means of a wheel-selective drive, torque vectoring is used on the steered axle, with the conventional focus on reducing the steering wheel torque. The yaw moment is inevitably influenced, so that the above-mentioned effects can also appear.

The steering force device is used to reduce the steering wheel torque to be applied by the driver to a desired level. A distinction is preferably made between two basic types that can be used alternatively: the hydraulically assisted steering systems (HPS, hydraulic power steering) and the electrically assisted steering systems (EPS, electric power steering), which are the standard in current cars. In the case of an electromechanical steering system, the assist torque of the steering force device is provided by an electric motor and, depending on the design, is initiated directly on the steering column or in the steering gear. The steering wheel torque is measured by a torque sensor and reported to a control unit. This calculates the necessary support torque, which the electric motor generates and transfers to the steering system via a gearbox. Furthermore, with an EPS system, a large number of additional functions can be implemented via the control unit, which enable the use of modern driver assistance systems (e.g. parking assistant, lane departure warning system).

A superimposed steering system is also provided as an option. The superimposed steering changes the steering ratio in that, in addition to the steering wheel angle set by the driver, it introduces an adjusting angle in a superimposed gear without changing the steering wheel angle. As a result, the directness of the steering is adjusted depending on the driving situation. This enables stable, indirect steering behavior (large steering ratio) at high speeds and direct, agile steering (small steering ratio) when driving around town and when parking. Stabilizing steering interventions by the assistance systems are also possible without disruptive feedback to the driver. The superimposed steering is preferably implemented with the components described above.

In the context of the invention it is proposed that the vehicle has an actuator module, wherein the actuator module is designed in terms of programming and / or circuitry to control the first and the second steering force module. The actuator module can be designed as a software module and / or as a hardware module.

According to the invention, it is provided that the actuator module controls the other two modules in such a way that an intermediate section of the steering system is elastically tensioned between the steering force device and the driven wheels. The actuator module forms a control device for controlling the strength of the elastic tension. In particular, a control and / or regulating circuit is formed, the strength of the elastic tension forming a manipulated variable. The strength of the elastic bracing can for example be designed as an elastic deformation of the tie rods brought about by axial forces in the tie rods as part of the intermediate section. For example, a value for the elastic tension can be specified as a setpoint value, e.g. by a control device via an interface, which is then set via the actuator module as the control device.

It is a consideration of the invention that the strength of the elastic tension can be set in a targeted manner through a targeted and joint control of the first and the second steering force module, and thereby the vehicle dynamics can be intervened. In particular, the use of steering force assistance by means of wheel-selective drives reduces the elastokinematic effects in the steering system, since the assistance force is applied directly at the wheel contact point. This relieves the load on the entire steering system, which results in less elastic deformation. In the conventional steering power assistance device, on the other hand, only that part of the steering system that is located between the steering wheel and the steering power assistance device is relieved.

A targeted use of this effect in combination with the occurring torque vectoring enables a targeted influence on the directness of the vehicle and / or a variation of the steering wheel angle requirement.

In a preferred embodiment of the invention, a bracing of the intermediate section can be set by the actuator module. The bracing of the intermediate section is preferably set as a function of a speed of the vehicle. The tension is preferably kept constant at a constant speed. In this embodiment, it is possible to set a lower tension in the intermediate section and thus a resulting greater directness in the steering system when the steering angle is changed at low speed (e.g. less than 30 km / h) and only when the steering angle is changed at higher speeds (e.g. greater than 100 km / h) to increase the tension and in particular to lower the directness.

It is particularly preferred that the actuator module is designed to control the first steering force module to change the steering angle in a first direction and at the same time control the second steering force module to change the steering angle in a second direction. As an alternative or in addition, the two steering force modules are activated to rotate the steering angle in opposite directions. By rotating in opposite directions, the intermediate section of the steering system is elastically tensioned between the wheel-selective drive and the steering force device.

In a preferred development, it is provided that the actuator module has an input interface for accepting information about a superimposed steering angle change, the actuator module being designed to control the first and the second steering force module as an input variable as a function of the superimposed steering angle change, so that the superimposed steering angle is realized and the resulting change in the steering wheel angle is compensated and / or reduced. The vehicle preferably has an assistance system which initiates the change in the steering angle.

In combination with an assistance system of this type that carries out steering corrections (e.g. lane departure warning system), further effects can be used: By combining the steering force assistance by means of wheel-selective drives with the steering force device, there are two options for introducing the assistance force. These are on the one hand in the wheel-road contact and on the other hand in the steering system. The steering wheel torque applied to the steering wheel can be influenced by combining the two support forces. This results in a further degree of freedom, which allows any distribution of the two support forces for a given steering wheel torque. The distribution of the support forces in turn influences the load on the steering system between the wheel contact point and the steering force device. Since this load leads to an elastic deformation and thus to a differential angle, a differential angle can be specifically impressed in this way without influencing the steering wheel torque and thus the driver. This results in increased comfort in assistance systems (for example lane keeping assistance), since the steering force device and / or the wheel-selective drive can compensate for the reaction of the steering intervention generated by the wheel-selective drives on the driver.

In principle, the wheel-selective drive can be designed, for example, as two independent drives that are close to the wheel.

In a preferred embodiment of the invention, the wheel-selective drive is designed as two electric motors, an electric motor being assigned to each of the driven wheels. In particular, the electric motors are designed as wheel hub motors. In this embodiment, no constructive additions are necessary in order to use the wheel-selective drive to control the steering forces.

Another object of the invention relates to a vehicle which is implemented as described above. The vehicle is designed to implement the method described above.

• 1 Reifen-Fahrbahn-Kontakt angreifende Kräfte am Beispiel des linken Vorderrades nach Pfeffer, P., & Harrer, M. (Hrsg.). (2013). Lenkungshandbuch : Lenksysteme, Lenkgefühl, Fahrdynamik von Kraftfahrzeugen. Wiesbaden: Springer Vieweg;
• 2 Funktionsprinzip einer Lenkkraftunterstützung mittels radselektiver Antriebe; links ohne und rechts mit Lenkkraftunterstützung; Lenkgeometrie vereinfacht (Spreizungswinkel 0°, Nachlaufwinkel 0°);
• 3 Lineares Einspurmodell einer Lenkung, stationäre Kreisfahrt;
• 4 Graph zur Darstellung von dem Lenkwinkel über den Lenkradwinkel, Einflüsse des Torque Vectoring und der Elastokinematik;
• 5 Graph zur Illustration der Reduktion der Auswirkung des Lenkeingriffs am Lenkrad;
• 6 schematische Darstellung eines Fahrzeugs zur Umsetzung des Verfahrens.

Further features, advantages and effects of the invention emerge from the following description of a preferred exemplary embodiment of the invention and the figures. These show:

• 1 Forces acting on tire-road surface using the example of the left front wheel according to Pfeffer, P., & Harrer, M. (Eds.). (2013). Steering manual: steering systems, steering feel, driving dynamics of motor vehicles. Wiesbaden: Springer Vieweg;
• 2 Functional principle of steering power assistance by means of wheel-selective drives; left without and right with power assistance; Steering geometry simplified (angle of spread 0 °, caster angle 0 °);
• 3 Linear single-track model of a steering system, stationary circular travel;
• 4th Graph to show the steering angle over the steering wheel angle, influences of torque vectoring and elastokinematics;
• 5 Graph to illustrate the reduction in the effect of the steering intervention on the steering wheel;
• 6th schematic representation of a vehicle for implementing the method.

Zwischen Lenkradwinkel und Lenkwinkel besteht aufgrund kinematischer Zusammenhänge/Ketten im Lenksystem eine definierte Abhängigkeit. Wird das System als starr betrachtet und treten keine elastischen Effekte auf, wird dieser Zusammenhang als Lenkübersetzung bezeichnet. Das Verhältnis zwischen Lenkradwinkel und Lenkwinkel ist im Allgemeinen während des Fahrbetriebs jedoch aufgrund elastischer Verformungen des Lenksystems inkl. Radträger (Kräfte auf Radaufhängung) nicht konstant. Diese elastischen Verformungen wirken einer Lenkbewegung entgegen, das Lenksystem wird in eine Geradeausstellung „gedrückt“. Je größer die das Lenkmoment beeinflussenden Kräfte sind, desto größer ist die elastische Verformung und damit der Lenkaufwand des Fahrers. Das heißt, dass der benötigte Lenkradwinkel zum Durchfahren einer Kurve hierdurch vergrößert wird. Der zum Erreichen eines Lenkwinkels am Rad notwendige Lenkradwinkel wird im Folgenden als Lenkradwinkelbedarf bezeichnet.To drive through a curve with a defined radius R (according to the single-track model, 3 ) for a vehicle with wheelbase l, a steering angle δ consisting of the Ackermann steering angle and the difference between the slip angles α _v and α _{h is} required: $$\delta =\frac{l}{\mathrm{R.}}+{\alpha }_v-{\alpha }_H$$

There is a defined relationship between the steering wheel angle and the steering angle due to kinematic relationships / chains in the steering system. If the system is considered to be rigid and no elastic effects occur, this relationship is referred to as the steering ratio. The ratio between steering wheel angle and steering angle is generally not constant during driving, however, due to elastic deformations of the steering system including wheel carriers (forces on the wheel suspension). These elastic deformations counteract a steering movement, the steering system is "pushed" into a straight-ahead position. The greater the forces influencing the steering torque, the greater the elastic deformation and thus the driver's effort to steer. This means that the required steering wheel angle for driving through a curve is increased as a result. The steering wheel angle required to achieve a steering angle on the wheel is referred to below as the steering wheel angle requirement.

This steering wheel angle requirement is also influenced by the torque vectoring generated by means of wheel-selective drives. The yaw moment caused by torque vectoring (which favors cornering) on the one hand reduces the front slip angle and on the other hand increases the rear slip angle. As is clear from the relationship mentioned at the beginning, this makes the steering angle to achieve the same curve radius smaller than with conventional systems. Furthermore, by reducing the front slip angle, the lateral forces at the front are reduced. This results in a reduction in the restoring forces and thus a further influence on the steering torque / steering wheel torque. The elastokinematic effect is also influenced, which results in a further reduction in the steering wheel angle requirement. In 4th these two effects are shown schematically. If the steering wheel angle remains the same, the effective steering angle is increased by torque vectoring or the necessary steering wheel angle is reduced with the same curve radius. An opposite effect is achieved by the elastokinematic effects. With the steering wheel angle remaining the same, the effective steering angle is reduced or the steering wheel angle required to drive through the same curve radius is increased.

The correction angle that can be realized by means of elastic bracing is limited because of the limiting strengths of the components of the steering system. However, the system is able to carry out small corrections without affecting the driver and, in the case of larger steering angle corrections, can attenuate them and forward them to the driver to a reduced extent. In this way, the steering wheel angle profile caused by assistance systems can be smoothed and the driving comfort can be increased.

In the 5 a situation A is shown first, with the assistance system causing a change in the steering angle, which can be seen from the upward deflection of the curve. The corrective intervention was fully compensated by the elastic bracing, so that no change can be seen in the steering wheel angle. In situation B, however, the steering angle change is greater, so that a complete compensation of the effect on the steering wheel angle is not possible. In situation B, there was therefore only a damping of the corrective intervention on the steering wheel angle. In the cases shown, the noticeable effect of the corrective intervention on the steering wheel is either completely suppressed (situation A) or at least partially suppressed (situation B). The graphic assumes that the steering angle can be set by +/- 0.3 °, the kinematic steering ratio is constant and is 13.

The 6th shows a vehicle in a schematic representation 1 to implement the procedure described above. The vehicle 1 has a steered axle 2 and a non-steered axle (not shown). On the steered axle 2 are driven wheels 3 arranged with the driven wheels 3 are driven by a wheel-selective drive, which is driven by two electric motors 4th is realized. The electric motors 4th are directly on the driven wheels 3 arranged. For example are the electric motors 4th designed as wheel hub motors. Each of the driven wheels 3 is an electric motor 4th exclusively assigned.

The vehicle 1 has a steering system 5 on what a steering wheel 6th for operation by the driver, a steering column 7th as well as coupling elements, designed as tie rods 8th , for transferring the steering torque to the wheel carrier 9 having. The steering system 5 has a steering force device 10 on which additionally or exclusively a steering torque in the steering system 5 can bring in.

To control the steering force device 10 instructs the vehicle 1 a first steering force module 11 on. To control the wheel-selective drive, the vehicle has 1 a second steering force module 12th on. The vehicle also has 1 an actuator module 13th on, which is formed, the first and the second steering force module 11 , 12th to control. For example, the steering force modules 11, 12 and the actuator module 13th into a control device 14th integrated. The control device 14th can be a central control device of the vehicle 1 but it can also be a decentralized control module.

Between the steering mechanism 10 and the driven wheels 3 is an intermediate section 15th the steering system 5 arranged. The actuator module 13th is formed, the first and the second steering force module 11 , 12th to be controlled so that the intermediate section 15th is elastically tensioned. This is achieved by using the steering force device 10 and the wheel-selective drive can be controlled in such a way that an opposing steering angle on the driven wheels 3 would be generated. By bracing the intermediate section 15th is that possible, the directness of the steering system 5 to influence or interventions by assistance systems 16 which lead to a change in the steering angle, to dampen or compensate so that there is no steering wheel angle change or only a damped steering wheel angle change.

List of reference symbols

1

vehicle

2

steered axle

3

driven wheels

4th

Electric motor of the wheel selective drive

5

Steering system

6th

steering wheel

7th

Steering column

8th

Tie rods

9

Wheel carrier

10

Steering force device

11

first steering force module

12th

second steering force module

13th

Actuator module

14th

Control device

15th

Intermediate section

16

Driver assistance system

Claims (10)

Method for controlling a vehicle (1), wherein the vehicle (1) has at least one steered axle (2) with driven wheels (3), the driven wheels (3) being driven via a wheel-selective drive (4), the vehicle (1) has a steering system (5) with a steering force device (10), the vehicle (1) having a first steering force module (11) for controlling the steering force device (10) and a second steering force module (12) for controlling the wheel-selective drive (4) characterized by an actuator module (13) for controlling the first and second steering force modules (11, 12), these being controlled so that an intermediate section (15) of the steering system (5) between the steering force device (10) and the driven wheels (3) is elastically tensioned, the actuator module (13) forming a control device for the strength of the elastic tensioning as a manipulated variable. Procedure according to Claim 1 , characterized in that a bracing of the intermediate section (15) can be set by the actuator module (13). Procedure according to Claim 1 or 2 , characterized in that the actuator module (13) is designed to control the first steering force module (11) for changing the steering angle in a first direction and at the same time the second steering force module (12) for changing the steering angle in a second direction, so that the intermediate section ( 15) of the steering system (5) is elastically tensioned between the wheel-selective drive (4) and the steering force device (10). Procedure according to Claim 3 , characterized in that the actuator module (13) has an input interface for a vehicle speed, the tension being set as an input variable as a function of the driving speed. Method according to one of the preceding claims, characterized in that the actuator module (13) has an input interface for accepting information about a superimposed steering angle change, the actuator module (13) being designed to have the first and second input variables as an input variable depending on the superimposed steering angle change To control the steering force module (11, 12) so that the superimposed steering angle is unchanged and the resulting steering wheel angle change is compensated and / or reduced. Procedure according to Claim 5 , characterized in that the change in the steering angle is initiated by a driver assistance system (16). Method according to one of the preceding claims, characterized in that the elastic bracing is carried out at the same time and / or synchronized with the superimposed change in the steering angle. Method according to one of the preceding claims, characterized in that the steering force device (10) is powered by an external energy source and is designed in particular as an electrical, pneumatic or hydraulic steering force device. Method according to one of the preceding claims, characterized in that the wheel-selective drive has two electric motors (4), an electric motor (4) being assigned to each of the driven wheels (3). Vehicle with a steered axle (2) with two driven wheels (3), the driven wheels (3) being driven via a wheel-selective drive (4), with a steering system (5), the steering system (5) having a steering force device (10 ), with a first steering force module (11) for controlling the steering force device (10) and with a second steering force module (12) for controlling the wheel-selective drive (4), characterized by an actuator module (13) for controlling the first and the second steering force module ( 11, 12), the actuator module (13) being designed to control it so that an intermediate section (15) of the steering system (5) is elastically tensioned between the steering force device (10) and the driven wheels (3), the actuator module ( 13) forms a control device for the strength of the elastic tension as a manipulated variable.

Images