WO2018028818A1

WO2018028818A1 - Motor vehicle

Info

Publication number: WO2018028818A1
Application number: PCT/EP2017/000926
Authority: WO
Inventors: Dieter Ammon; Magnus Rau; Steffen Wagner; Ralph Streiter; Claus-Michael Hainbuch
Original assignee: Daimler Ag
Priority date: 2016-08-06
Filing date: 2017-07-31
Publication date: 2018-02-15
Also published as: DE102016009586A1

Abstract

The invention relates to a motor vehicle (1), comprising a front axle steering mechanism (7), by means of which an instantaneous front steering angle of the front wheels (3) of the motor vehicle (1) can be adjusted, and a rear axle steering mechanism (9), by means of which an instantaneous rear steering angle of the two rear wheels (4) of the motor vehicle (1) can be adjusted. According to the invention, the rear axle steering mechanism (9) is designed such that, when the motor vehicle (1) is cornering, the position of an instantaneous rotational point (14) on the central longitudinal axis (M) of the motor vehicle can be varied by the variation of the instantaneous rear steering angle.

Description

motor vehicle

The invention relates to a motor vehicle.

Motor vehicles with an actively controllable rear axle steering, for example, allow a manipulation of the yaw rate or the transverse speed of the

Motor vehicle by adjusting the set in the rear wheels of the motor vehicle, so-called steering angle.

Against this background, WO 2005/044650 A1 deals with an apparatus and a method for determining a pivot point of a motor vehicle by one

Vehicle axis. The device is configured such that it determines the pivot point in dependence on a current yaw rate and a current slip angle of the motor vehicle.

The ratio of said two state variables, that is, yaw rate and lateral velocity can be determined by the instantaneous position of the fulcrum of the

Motor vehicle to be described about its vertical axis along the central longitudinal axis of the motor vehicle. But said position can just when Kurvenfahrteh des

Motor vehicle and for this required steering intervention by the driver of the motor vehicle vary along the central longitudinal axis. Typical is just at

Cornering the motor vehicle a pronounced transient response to the position of the pivot along the central longitudinal axis, which is perceived by the driver as not intuitive and thus unpleasant.

It is therefore an object of the present invention, in the development of methods for controlling motor vehicles with active rear axle steering when cornering to show new ways and in particular to provide a method in which

Cornering by the driver of a motor vehicle with active rear-axle steering is perceived as particularly intuitive and therefore particularly pleasant. This object is solved by the subject matter of the independent patent claims. Preferred embodiments are subject of the dependent claims.

The basic idea of the invention is accordingly the position of a pivot of the

Motor vehicle to keep constant about its vertical axis along the central longitudinal axis, either at a predetermined position of the central longitudinal axis of the motor vehicle or at least within a predetermined range on the central longitudinal axis. As a fulcrum that point is defined on the central longitudinal axis of the motor vehicle, in which the instantaneous transverse speed during cornering has a zero value.

The fixation of the fulcrum takes place in the case of the motor vehicle according to the invention presented here in the sense of regulating the position of the fulcrum on the motor vehicle

Center longitudinal axis as a controlled variable. As a manipulated variable of such a control loop, the adjustable instantaneous rear steering angle of the rear wheels of the motor vehicle can be used. This can be varied by means of a control / regulating device present in the motor vehicle and a rear-axle steering system cooperating with the control / regulating device. This allows the desired keeping constant the position of the pivot point on the central longitudinal axis. The control / regulating device can be designed as a conventional control unit and can also provide other important in connection with the control of the rear axle steering functionalities.

The driving behavior of the motor vehicle associated with the previously described regulation of the pivot point position is perceived by the driver as particularly pleasant and intuitive, ie "comprehensible", so that the driver perceives the motor vehicle as particularly easy to control.

A motor vehicle according to the invention comprises a front axle steering, by means of which an instantaneous front steering angle of the front wheels of the motor vehicle can be adjusted by actuation of a hand steering wheel present in the motor vehicle.

Furthermore, the motor vehicle has a rear axle steering, by means of which, preferably of a control / regulating device present in the motor vehicle, an instantaneous rear steering angle of the two rear wheels of the vehicle

Motor vehicle can be adjusted. According to the invention, the rear axle steering designed so that when cornering of the motor vehicle by varying the instantaneous rear steering angle, the position of a current Drehpols along the central longitudinal axis of the motor vehicle is variable. In the present case, a momentary pivot point is defined as a projection of the instantaneous pole of the motor vehicle along the transverse direction of the motor vehicle on its central longitudinal axis. As a fulcrum - with respect to a top view of the motor vehicle from above - that point of the motor vehicle defined in which during cornering the instantaneous transverse speed of the motor vehicle has a zero value. As a fulcrum distance, the distance of the fulcrum from the center of gravity S of the motor vehicle 1 along the

Center longitudinal axis M denotes.

In a preferred embodiment, the fulcrum is defined as the point in a plan view of the motor vehicle in which, during cornering, the instantaneous lateral velocity of the motor vehicle has a zero value.

In a further preferred embodiment, the motor vehicle comprises a cooperating with the rear axle steering control / regulating device by means of which the instantaneous rear steering angle is adjustable. In this variant, the control / regulating device is designed as a control unit, which by

Adjusting the current rear steering angle controls the current pivot point to a constant position along the central longitudinal axis of the motor vehicle. In this way, the desired, advantageous driving behavior of the motor vehicle in

Driving on the curve can be achieved.

In a preferred embodiment, the constant position of the fulcrum on the central longitudinal axis is determined in dependence on at least one predetermined parameter.

Suitably, the at least one predetermined parameter may be the speed or the lateral acceleration of the motor vehicle. In other variants but also other parameters can be used. This allows a very flexible

Fulcrum control depending on different sizes.

In an advantageous development, the dependence of the constant position on the predetermined parameter in a characteristic field is defined and / or stored. The constant or constant position of the fulcrum on the central longitudinal axis is expediently determined as a function of various variables, for example the instantaneous transverse speed and the instantaneous yaw rate of the motor vehicle.

Suitably, the predetermined region of the central longitudinal axis can be assigned to a predefined driving program of the motor vehicle.

Particularly preferably, at least a first and a second area are provided, wherein the first area is assigned a first driving program and the second area is assigned a second driving program. Depending on the position of the fulcrum on the central longitudinal axis can thus be a specific driving program (in the form of characteristics or Ken fields), and consequently, a certain driving behavior of the motor vehicle, when

Drive on the curve.

In an advantageous development of the first driving program of the fulcrum on the central longitudinal axis with respect. The direction of travel behind a center of gravity of the motor vehicle and in the second driving program with respect. The direction of travel before the center of gravity. In this way, driving programs with individual driving behavior of the

Motor vehicle defined.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components. In each case show schematically:

Fig. 1 shows an example of a motor vehicle according to the invention in one

Side View,

Fig. 2 shows the motor vehicle of Figure 1 in a plan view during a

Cornering,

Fig. 3 is an alternative to Figure 2 representation for explaining the

Position determination of the center of rotation on the central longitudinal axis of the

Motor vehicle.

FIG. 1 shows an example of a motor vehicle 1 according to the invention in one embodiment

Side view. 2 shows the motor vehicle 1 in a plan view during cornering. The trajectory of this cornering is indicated in Figure 2 by an arrow with the reference numeral 13. The motor vehicle 1 therefore passes through a left turn.

The motor vehicle 1 comprises one only roughly illustrated in FIG

Vehicle frame 2 and front wheels 3 and rear wheels 4. As the plan view of Figure 2 reveals, the front wheels 3 are arranged on a front axle 5 of the motor vehicle 1 and the rear wheels 4 on a rear axle 6 of the motor vehicle 1. On the front axle 5, a front axle steering 7 is formed, which in FIG. 2 only

roughly indicated. By means of the front axle steering 7, the driver of the motor vehicle 1 can adjust the instantaneous steering angle of the front wheels 5 by actuating a hand steering wheel 8, which is also indicated only schematically.

On the rear axle 6 an active rear axle steering 9 is formed, by means of which the instantaneous rear steering angle of the two rear wheels 4 of the motor vehicle 1 is adjustable.

The rear axle steering system 9 is controlled by a control / regulation device 10 provided in the motor vehicle 1, which can be designed as a conventional control unit. The control / regulating device 10 can this purpose a

Control unit 11 and a memory unit 12 include. From the control In the case of the cornering along the trajectory 13 shown in FIG. 2, the control device 10 is a pivot point 14 of the motor vehicle 1 about its vertical axis H as

Controlled variable regulated to a constant on the central longitudinal axis M of the motor vehicle 1 position.

The pivot point 14 is defined as the point on the central longitudinal axis M, in which the instantaneous lateral velocity v _{q has} a zero value when cornering. According to FIG. 2, an instantaneous yaw axis G along the vertical direction H of the motor vehicle 1 is fixed by the pivot point 14, around which the

Motor vehicle 1 performs a rotational movement. As a fulcrum distance, the distance of the fulcrum from the center of gravity S of the motor vehicle 1 along the

Center longitudinal axis M denotes.

In the following attention should be directed to the illustration of Figure 3, based on which the determination of the pivot point 14 is to be explained. In FIG. 3, compared to the illustration of FIG. 2, the front axle 5 with the two front wheels 3 is shown in simplified form. The same applies to the rear axle 6 with the two rear wheels 5. For clarity, in FIG. 3 the center of mass of the motor vehicle 1 is designated S with respect to the plan view shown.

The velocity vector v _{v of} the front axle 5 at the intersection 16 of the front axle 3 with the central longitudinal axis M is designated v _v in this simplified illustration. The velocity vector VH of the rear axle 6 at the intersection 17 of the rear axle 6 with the central longitudinal axis M is correspondingly denoted by v _H. The orthogonal to the velocity vector vv passing through the intersection 16 is shown in FIG

Reference numeral 18 denotes. The orthogonal to the velocity vector vv passing through the intersection 17 is designated by reference numeral 19. Of the

Intersection between the two orthogonal 18, 19 is referred to as the instantaneous P pole (Momentanpol P). By projection of the instantaneous center of rotation P

(Momentanpols P) along the transverse direction Q of the motor vehicle 1 - this is perpendicular to the longitudinal direction L of the motor vehicle 1, which is defined by the central longitudinal axis M - on the central longitudinal axis M results in the desired instantaneous pivot point 14 of the motor vehicle first When driving the trajectory 13, for example, in the form of a left turn due to the steering engagement by means of the Vorderachslenkung 7 by the driver, the position of the pivot point 14 along the central longitudinal axis M vary, which is indicated in Figure 2 by further, exemplary drawn pivot points 14 *.

In order to keep the position of the pivot point 14 on the central longitudinal axis M constant, it is first necessary, the current actual value of the pivot point 14 on the

Center longitudinal axis M to determine. This can be done by evaluating the current ones

Transverse speed and the current yaw rate d / dt ψ happen.

For this purpose, the motor vehicle 1 a yaw rate sensor 16 for determining the current yaw rate of the motor vehicle 1 and / or a

Speed sensor 15 for determining the instantaneous transverse speed of the motor vehicle 1 transverse to the central longitudinal axis M include.

In order to keep the position of the pivot point 14 when cornering on the central longitudinal axis M constant, the adjustable by means of the active rear axle steering 9 rear steering angle of the two rear wheels 4 of the control / regulating device 10 is adjusted accordingly. The control / regulating device 10 is as

Regulated unit formed by adjusting the current rear

Steering angle controls the current pivot point 14 to a constant position along the central longitudinal axis M of the motor vehicle 1.

The position of the pivot point P on the central longitudinal axis M may be determined in dependence on one or more predetermined parameters. As appropriate

Parameters are in particular the speed and the lateral acceleration of the motor vehicle 1 into consideration. In other variants, however, other, other parameters can be used. Such a functional dependency of the constant position on the predetermined parameter can be defined in a characteristic map which can be stored in a memory present in the control / regulation device 10. In the control / regulating device can several

Maps are stored, each map can be assigned to a specific driving program of the motor vehicle.

In the example scenario, the motor vehicle 1 has a first and a second driving program. When the first driving program is activated, the pivot point 14 is on the central longitudinal axis M in the direction of travel F in an area behind a center of gravity S of the motor vehicle 1 is arranged. Such a (first) region of the central longitudinal axis M is in FIG. 2

designated by the reference numeral 20a by way of example. When activated second

Driving program, the pivot point 14 on the central longitudinal axis M in the direction of travel F is arranged in front of the center of gravity S of the motor vehicle 1. Such a (second) region of the central longitudinal axis M is designated by reference numeral 20b in FIG. 2 by way of example. The first driving program is accompanied by one of the occupants of the motor vehicle 1 typically perceived as comfortable or "leisurely" behavior of the motor vehicle 1. The second driving program is one of the occupants of the motor vehicle 1 usually perceived as athletic or "agile" driving behavior Motor vehicle 1 associated.

In the example of Figures 2 and 3, the front wheels 3 from the central longitudinal axis M away to the left and the rear wheels 4 away from the central longitudinal axis M to the right

aligned. In this scenario, the pivot point 14 is located on the central longitudinal axis M in the region 20a between the center of gravity S and the rear axle 6, ie with respect to a direction of travel F of the motor vehicle 1 behind the center of gravity S. FIG. 3 thus shows the motor vehicle 1 with the first driving program activated.

It is clear that the two above-explained driving programs are to be understood as purely exemplary and that further driving programs can be defined, in which the pivot point 14 in dependence on the parameters mentioned both in the region 20a, ie before the center of gravity S, and in the region 20b, that is, behind the center of gravity S, can be arranged.

Claims

claims

1. motor vehicle (1),

with a front axle steering (7), by means of which an instantaneous front steering angle of the front wheels (3) of the motor vehicle (1) is adjustable,

with a rear axle steering (9), by means of which a momentary rear

Steering angle of the two rear wheels (4) of the motor vehicle (1) is adjustable, wherein the Hinterachslenkung (9) is formed such that when cornering the motor vehicle (1) by varying the instantaneous rear steering angle, the position of a current pivot point (14) on the Center longitudinal axis (M) of the motor vehicle is variable,

wherein the fulcrum (14) is defined as the point in a top plan view of the motor vehicle (1) in which, during cornering, the instantaneous lateral velocity of the motor vehicle (1) has a zero value,

wherein the motor vehicle comprises a control / regulating device (10) cooperating with the rear axle steering (9), by means of which the instantaneous rear steering angle is adjustable,

characterized in that

the control / regulating device (10) is designed as a control unit, which regulates the current pivot point (14) to a constant position or a predetermined range on the central longitudinal axis (M) of the motor vehicle (1) by adjusting the instantaneous rear steering angle.

2. Motor vehicle according to claim 1,

characterized in that

the constant position of the fulcrum (14) on the central longitudinal axis (M) is determined as a function of the instantaneous speed (v) and the instantaneous lateral acceleration of the motor vehicle (1).

3. Motor vehicle according to one of the preceding claims, characterized in that

the position of the pivot point (14) with increasing speed and with increasing lateral acceleration of the motor vehicle (1) on the central longitudinal axis (M) to the front, to a front longitudinal end of the motor vehicle, wanders.

Motor vehicle according to one of the preceding claims,

characterized in that

the motor vehicle (1) comprises a yaw rate sensor (16) for determining the current yaw rate of the motor vehicle (1) and / or a speed sensor (15) for determining the instantaneous lateral speed of the motor vehicle (1).

Motor vehicle according to claim 4,

characterized in that

the predetermined range of the central longitudinal axis (M) in the control / regulating device (10) adjustable, predefined driving program of the

Motor vehicle (1) is assigned.

Motor vehicle according to claim 5,

characterized in that

at least a first and a second area (20a, 20b) are provided, wherein the first area (20a) is a first driving program and the second area

(20b) is assigned a second driving program.

Motor vehicle according to claim 6,

characterized in that

in terms of the direction of travel behind a center of gravity (S) of the motor vehicle (1) and in the second driving program with respect to the direction of travel (F) in front of the center of gravity (S) is arranged in the first driving program, the pivot point (14) on the central longitudinal axis (M).