DE102014104779A1 - Method for roll stabilization - Google Patents

Abstract

The invention relates to a control device and a method for roll stabilization of a body of a vehicle, wherein the body has four suspensions each having a vibration damper, wherein the vibration damper between the body and a movably mounted with respect to the Karoserie suspension are arranged, wherein the vibration damper formed in the manner in that a damping force is adjustable for each vibration damper, wherein two front vibration absorbers are disposed on opposite sides of a front portion of the body, wherein two rear vibration damper are disposed on opposite sides of a rear portion of the body, wherein a first roll speed for a front Section of the body and a second roll speed for a rear portion of the body is determined, depending on the two measured roll speeds a Dämpfungskr aft is adjusted for at least one vibration damper in such a way that a rolling movement of the body is counteracted.

Description

The invention relates to a method for roll stabilization according to claim 1 and a control device according to claim 12.

Out DE 10 2011 005 348 A1 is a roll stabilization system for a two-lane, two-axle vehicle known. In this case, an electronic control unit is provided which, taking into account suitably obtained level signals of individual vehicle wheels relative to the vehicle body in relation to each other when the vehicle with only one wheel only one axis on a relative to the footprint of the other three wheels significant raised or lowered Contact surface is located and / or on such ascends or descends, controls the roll stabilization system in such a way that the load of the vehicle body is reduced by a torsion introduced by the suspension torsional to the same vehicle operating condition without such control of the roll stabilization system.

The object of the invention is to provide an improved method for roll stabilization of a body of a vehicle.

The object of the invention is achieved by the method according to claim 1 and by the control device according to claim 12.

An advantage of the method described is that a more precise and accurate roll stabilization is achieved. This advantage is achieved by taking into account a rolling speed of a front portion of the body and a rolling speed of a rear portion of the body in the determination of a damping force for at least one vibration damper. In this case, a more accurate model is used to take into account the vibration characteristics of the body, in which the body is divided into a front portion and a rear portion. Thus, it is possible for the front portion and the rear portion of the body to wobble at different speeds about a longitudinal axis. Thus, with the aid of the newly proposed method with higher accuracy, a more efficient damping of the rolling motion can be determined.

In one embodiment, when calculating the damping force, in-phase and out-of-phase vibrations of the front and rear portions of the body are considered. In this way, an increased accuracy in the determination of the damping force is achieved.

In another embodiment, a front inertia is used to determine the damping force for the front portion of the body, and a rear inertia is used for the rear portion of the body, wherein the front and rear inertia are coupled together by a predetermined torsional stiffness. In this way, a precise determination of the damping force for damping the rolling motion of the vehicle is made possible.

In another embodiment, both the damping force for a tensile load and the damping force for a compressive load of the at least one vibration damper is determined, in particular calculated and controlled accordingly to dampen the rolling motion. As a result, a further improvement in roll stabilization can be achieved.

In a further embodiment, the damping forces for at least two vibration dampers, in particular for all vibration dampers, are determined, in particular calculated. As a result, an improved roll stabilization is achieved.

In one embodiment, a damping torque for the front portion is determined depending on the first and the second roll speed, in particular calculated, wherein depending on the damping torque damping forces for the two vibration absorbers of the front portion are determined and adjusted in such a way that the Damping torque is distributed to the two vibration damper. Thereby, an improved control of the damping forces of the front portion is achieved.

In a further embodiment, a damping torque is determined for the rear portion depending on the first and the second roll speed, in particular calculated, wherein damping forces of the two damper of the rear portion are adjusted in such a way that the damping torque is distributed to the two vibration damper. As a result, an improved control of the damping forces is achieved.

Depending on the selected design, the damping forces for the two vibration dampers of the front and the rear section are set equal. In a vibration damper of one section is a tensile force and the other vibration damper of the same section, a compressive force is set. Thus, the vibration damper are evenly loaded.

In a further embodiment, same damping measures are used for the vibration dampers, in particular for the vibration absorbers of the front section and the vibration absorbers of the rear section of the body. In this way, a simple and quick calculation of the damping forces is possible.

In another embodiment, different damping measures are used in the calculation of the damping force for the front and rear vibration dampers. In this way, a more precise adjustment of the damping forces is achieved.

The invention will be explained in more detail below with reference to FIG.

The figure shows a schematic representation of a body 1 of a vehicle in a front section 2 and in a rear section 3 is divided. The front section 2 and the back section 3 are considered as ideally rigid plates that pass over an element 4 are in operative connection with each other, wherein the element 4 a torsionally rigid connection between the front and the rear section 2 . 3 represents. Thus, the front section can 2 and the back section 3 according to the model used only twist against each other. The twist is in a central longitudinal axis 5 possible through a center of the sections viewed in relation to the width 2 . 3 and the element 4 runs. The longitudinal axis 5 extends along an X-axis. Perpendicular to the X-axis, a Y-axis is shown, which is a transverse direction to the body 1 represents. A Z axis is arranged perpendicular to the XY plane. At the front section 2 are on opposite front corners 6 . 7 one suspension each 8th . 9 provided, which is movable on the bodywork 1 are attached. Each front suspension 8th . 9 is about a vibration damper 10 . 11 in operative connection with the body 1 , In addition, at the first and the second front suspension 8th . 9 one wheel each 12 . 13 attached.

Analogously, a first and a second rear suspension 14 . 15 provided, each movable relative to the bodywork 1 are mounted and each have a first and a second rear vibration damper 16 . 17 with the back section 3 the body 1 communicates. The first and the second rear vibration damper 16 . 17 are in a third or fourth corner area 20 . 23 the rear section 3 the body 1 arranged. In addition, on every rear suspension 14 . 15 one wheel each 18 . 19 attached. Every bike 12 . 13 . 18 . 19 is in each case a first sensor 20 assigned. In addition, every corner area 6 . 7 . 22 . 23 in each case a second sensor 21 assigned. The front and rear vibration absorbers 10 . 11 . 16 . 17 are formed in such a way that a damping force of each vibration damper 10 . 11 . 16 . 17 by a control signal of a control unit 25 can be adjusted and changed. A vibration damper can, for. B. in the form of an actuator, and / or a hydraulic shock absorber.

wobei mit v_{Aufbau FL} die Geschwindigkeit des ersten vorderen Eckbereiches 6, mit v_{Aufbau FR} die Geschwindigkeit des zweiten vorderen Eckbereiches 7, mit v_{Aufbau RL} die Geschwindigkeit des dritten Eckbereiches 22, mit v_{Aufbau RR} die Geschwindigkeit des vierten Eckbereiches 23 bezeichnet sind. Mit Y_V wird eine erste Spurbreite zwischen dem ersten Rad 12 der ersten vorderen Radaufhängung 8 und dem zweiten Rad 13 der zweiten vorderen Radaufhängung 9 bezeichnet. Mit Y_H wird eine zweite Spurbreite zwischen dem dritten Rad 18 der ersten hinteren Radaufhängung 14 und dem vierten Rad 19 der zweiten hinteren Radaufhängung 15 bezeichnet.The first and the second sensors 20 . 21 are designed to measure a travel and / or an acceleration. Thus, using the sensors 20 . 21 the velocities in the Z-direction, ie perpendicular to the plane of the body 1 for the wheels 12 . 13 . 18 . 19 and for the corner areas 6 . 7 of the front section 2 and the corner areas 22 . 23 the rear section 3 be measured. It is important that the velocities in Z-direction are determined. Whether these are finally determined with acceleration sensors or with the help of the time derivative of level sensors, is irrelevant for the method described here. Using the sensors 20 . 21 become four speeds of the four corner areas 6 . 7 . 22 . 23 the body 1 calculated based on the measured accelerations of the corner areas and the wheels. According to the model used, the front section may be 2 opposite to the reference plane XY and thus also towards the rear section 3 around the longitudinal axis 5 twist. Thus, a front roll speed x. _V for the front section around the longitudinal axis 5 and a rear roll speed x. _H for the back section 3 around the longitudinal axis 5 calculated according to the following formulas:

where with v _{build FL} the speed of the first front corner area 6 , with v _{build FR} the speed of the second front corner area 7 , with v _{build RL} the speed of the third corner area 22 , with v _{build RR} the speed of the fourth corner area 23 are designated. Y _V becomes a first track width between the first wheel 12 the first front suspension 8th and the second wheel 13 the second front suspension 9 designated. Y _H becomes a second track width between the third wheel 18 the first rear suspension 14 and the fourth wheel 19 the second rear suspension 15 designated.

wobei mit C_V die Steifigkeit des vorderen Abschnittes 2, mit C_FL die Steifigkeit des ersten vorderen Schwingungsdämpfers 10, mit C_FR die Steifigkeit des zweiten vorderen Schwingungsdämpfers 11, mit Y_V die erste Spurbreite und mit C_{Stabi V} eine Steifigkeit eines nicht dargestellten Stabilisators bezeichnet ist. Die Steifigkeit des Stabilisators ist ein festgelegter Wert, der beispielsweise in einem Speicher 24 abgelegt ist. Der Speicher 24 steht mit einem Steuergerät 25 in Verbindung, das über einen Eingang 26 mit den Sensoren 20, 21 in Verbindung steht. Weiterhin steht das Steuergerät 25 über einen Ausgang 27 mit den Schwingungsdämpfern 10, 11, 16, 17 in Verbindung.In a further method step, rotational stiffnesses can be calculated, which changes in vehicles with air suspension whose spring rate is variable. The rotational stiffness for the front axle, ie for the front section 2 is calculated using the formula:

where C _{V is} the stiffness of the front section 2 , with C _FL, the stiffness of the first front vibration damper 10 , with C _FR, the stiffness of the second front vibration damper 11 , Y _{V is} the first track width and C _{Stabi V is} a rigidity of a stabilizer, not shown. The stiffness of the stabilizer is a fixed value, for example, in a memory 24 is stored. The memory 24 stands with a control unit 25 connected via an entrance 26 with the sensors 20 . 21 communicates. Furthermore, there is the control unit 25 via an exit 27 with the vibration dampers 10 . 11 . 16 . 17 in connection.

The stiffness for the rear section 3 is calculated according to the following formula:

With C _H is the rigidity of the rear section 3 , with C _RL the stiffness of the first rear shock absorber 16 , with C _RR the stiffness of the second rear shock absorber 17 , with Y _H the second track and C _{Stabi H} denotes the rigidity of a rear stabilizer, not shown. The rigidity of the rear stabilizer is in the data memory 24 stored.

Furthermore, for the rotational connection between the front section 2 and the rear section 3 a rotational stiffness c _{K of} the body 1 used, which is known and in the data store 24 is stored. Furthermore, a first moment of inertia J _V for the front portion 2 and a second moment of inertia J _H for the rear section 3 known and in the data store 24 stored.

With the described data or formulas natural frequencies of the body 3 calculated according to the following first rule:

In a following step, the two natural frequencies and the two resulting natural vibration vectors are calculated.

wobei mit M die Trägheitsmatrize und mit C die Steifigkeitsmatrize bezeichnet ist.As calculation example the following values are assumed:

where M is the inertial matrix and C is the stiffness matrix.

Furthermore, the following is the control unit 25 During operation of the vehicle in real time, for example in the form of a C programming, the first rule with the stated values is solved numerically:

The two solutions are the two natural frequencies: ω ₁ = 1.7 Hz and ω ₂ = 15.7 Hz.

The corresponding eigenvectors u ₁ , u ₂ satisfy the following conditions:

Numerically, these can be expressed as follows:

The modal matrix is thus:

In a following process step, the new coordinates are calculated according to the following formulas for the natural vibrations:

The equations are decoupled in the new coordinate system:

That is, the damping matrix K in the normal coordinate system is equal to and has the value 1 when a first damping amount D1 of the first natural frequency corresponding to a roll of the vehicle and a second damping amount D2 of the second natural frequency corresponding to twisting are equal to

Depending on the selected embodiment, the attenuation measures of the first and second natural vibration modes can also be chosen to be different in size and, for example, between 0.8 and 1.3. Thus, the torques are determined front and rear, dampen with the predetermined damping D ₁ and D _2, the two vibration modes of the structure rolling and twisting.

wobei mit M_V ein vorderes Dämpfungsmoment der vorderen Schwingungsdämpfer 10, 11 und mit M_H ein hinteres Dämpfungsmoment der hinteren Schwingungsdämpfer 16, 17 bezeichnet ist. Abhängig von der gewählten Ausführungsform können die Dämpfungsmomente abhängig von der ersten Wankgeschwindigkeit des vorderen Abschnittes und der zweiten Wankgeschwindigkeit des hinteren Abschnittes auch anhand von Tabellen, Kennlinien oder Kennfeldern ermittelt werden, die im Speicher 24 abgelegt sind.Subsequently, in a further method step, torques for the front and the rear vibration dampers 10 . 11 . 16 . 17 calculated according to the following formulas:

where M _{V is} a front damping torque of the front vibration damper 10 . 11 and with M _H a rear damping moment of the rear vibration damper 16 . 17 is designated. Depending on the selected embodiment, the damping torques can also be determined on the basis of tables, characteristic curves or characteristic maps which are stored in memory, depending on the first roll speed of the front section and the second roll speed of the rear section 24 are stored.

The front damping torque M _V is achieved using the front vibration dampers 10 . 11 on the front section 2 the body 1 exercised. The front damping torque is calculated using the first track width Y _V and the center of mass of the front section 2 the body in the longitudinal axis 5 converted into a damping force. Depending on the chosen design, the front vibration dampers 10 . 11 controlled in such a way that the front damping torque of both front vibration dampers 10 . 11 is applied uniformly, ie each front damper generates half of the front damping torque or the corresponding front damping force. This is done by the control unit 25 the damping force of the front vibration damper 10 . 11 adjusted accordingly. In this case, a compressive force is exerted by a vibration damper and the other vibration damper to a roll, ie a rotation about the longitudinal axis 5 to dampen. Depending on the selected design, the damping forces of the front vibration damper 10 . 11 be set to different sizes, but always the entire front damping torque and the front damping force is generated.

The rear damping torque M _H is using the rear vibration damper 16 . 17 on the back section 3 the body 1 exercised. The rear damping moment is converted to a rear damping force by means of the second track Y _H. Depending on the chosen design, the rear shock absorbers 16 . 17 controlled in such a way that the rear damping torque of both rear shock absorbers 16 . 17 is applied uniformly, ie each rear damper generates half of the rear damping torque and the rear damping force. For this purpose, the control unit adjusts the damping force of the rear vibration damper accordingly. In this case, a vibration damper exerts a tensile force and the other vibration damper a compressive force as a damping force to a roll, ie a rotation about the longitudinal axis 5 to dampen. Depending on the chosen design, the damping forces of the rear shock absorbers 16 . 17 be set to different sizes, but always the entire rear damping torque and the rear damping force is generated.

The damping moments can be in real time, for example every 2 ms from the control unit 25 determined, in particular calculated. In addition, the control unit 25 The vibration damper drive every 2 ms in such a way that the vibration damper generate the desired damping torque.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011005348 A1 [0002]

Claims (12)

A method for roll stabilization of a body of a vehicle, wherein the body comprises four suspensions, each having a vibration damper, wherein the vibration damper between the body and a movably mounted to the Karoserie suspension are arranged, wherein the vibration damper are formed in such a way that for each vibration damper A damping force is adjustable, wherein two front vibration damper are disposed on opposite sides of a front portion of the body, wherein two rear vibration damper on opposite sides of a rear portion of the body are arranged, wherein a first roll speed for a front portion of the body and a second roll speed is determined for a rear portion of the body, wherein, depending on the two measured roll speeds, a damping force for at least one vibration damper in the manner is set that a rolling movement of the body is counteracted. The method of claim 1, wherein the damping force for in-phase vibration of the front and the rear portion of the body is determined. Method according to one of the preceding claims, wherein a damping force for an antiphase oscillation of the front and the rear portion of the body is determined. Method according to one of the preceding claims, wherein for the determination of the damping force, a front inertia of the front portion and a rear inertia of the rear portion are taken into account, wherein the front and the rear inertia are coupled together via a predetermined torsional stiffness. Method according to one of the preceding claims, wherein the damping force for a tensile load or a compressive load of the at least one vibration damper is determined. Method according to one of the preceding claims, wherein the damping forces for the at least two vibration dampers, in particular for all vibration dampers are determined. The method of claim 6, wherein for the front portion of a damping torque is determined depending on the first and the second roll speed, wherein depending on the damping torque damping forces for the two vibration dampers of the front portion are determined and adjusted in such a way that the damping torque on the two Vibration damper is distributed. The method of claim 6, wherein for the rear portion of a damping torque is determined depending on the first and the second roll speed, wherein damping forces of the two vibration damper of the rear portion are adjusted in such a way that the damping torque is distributed to the two vibration damper. A method according to claim 7 or 8, wherein the damping forces for the two vibration dampers are set equal. Method according to one of the preceding claims, wherein the same damping amounts are used in the calculation of the damping forces for the front and the rear vibration damper. Method according to one of claims 1 to 9, wherein in the calculation of the damping forces for the front and rear vibration damper different damping measures are used. Control unit for controlling a damping force of at least one vibration damper, wherein the control device is designed to carry out a method according to one of the preceding claims.

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