DE102014018717A1 - Method for determining a center of gravity of a vehicle and vehicle control system - Google Patents

Abstract

The invention relates to a method for determining a center of gravity height (hs) of a vehicle (1), in particular a utility vehicle, in which driving dynamics values (a) of the vehicle (1) are determined during cornering, the driving dynamics values (a) being a a transverse dynamics of the vehicle descriptive transverse dynamics quantity (a) and a slip behavior or Reibwertverhalten the longitudinally accelerated, in particular braked wheels (VA-l, VA-r) a longitudinally accelerated, in particular braked axis (VA) descriptive slip include, and from the Vehicle dynamics values (a) and from a balance of forces and moment equilibrium during cornering and a center of gravity height (hs) is determined.

Description

The invention relates to a method for determining a center of gravity of a vehicle as well as a method for vehicle dynamics control and a vehicle control system, which use this method.

State of the art

In addition to the current driving dynamics variables such as wheel speeds, driving speed, yaw rate, etc., driving dynamics regulations of vehicles generally also use vehicle parameters or general and static information about the vehicle, such as the wheelbase and the total mass of the vehicle. Furthermore, as a vehicle parameter and the current center of gravity height of the vehicle helpful to the vehicle against tilting inclinations such. B. to protect a lateral tipping and the driver z. B. not be disturbed by unwanted engine or brake interventions.

The height of the center of gravity generally depends on the current load and thus can not be pre-parameterized in a vehicle, unlike vehicle parameters such as vehicle parameters. B. track width and wheelbase.

Known driving dynamics regulations estimate in part a possible center of gravity height from the determined total mass of the vehicle; In this case, in general, a worst-case possible center of gravity height, i. H. a "worst case", used to detect possible instabilities can.

However, such methods of estimating the center of gravity are relatively uncertain and affect regulation of vehicle behavior. An instability in driving behavior is thus sometimes not recognizable or too late, or there are unnecessary control interventions.

The US 2012/0173133 A1 shows a method for estimating the center of gravity height of a biaxial vehicle. Here, in several braking phases on roads with substantially the same slope with different acceleration or deceleration braked, and estimated during the braking phases, the vehicle acceleration, slip rate of the front and rear axle, braking forces or braking torques on the axes or a ratio thereof, and the slope of the road ,

The DE 100 536 05 B4 shows the determination of the center of gravity height by determining the difference of wheel contact forces and a lateral acceleration, these values are related to each other and a rolling model is evaluated. The wheel contact forces are determined by special sensors. In the evaluation, changes in the difference in wheel contact forces are compared with changes in the lateral acceleration.

The DE 10 247 993 B4 shows a method for determining the center of gravity height of a vehicle, in which the lateral acceleration of the vehicle and the change of a roll rate are determined. The roll rate is determined as a change over time of a roll tilt, which is determined in particular by a relative comparison of the orientation of the road surface relative to the vehicle. However, such measurements are generally inaccurate.

The DE 199 04 216 A1 shows a method for determining the risk of tipping a vehicle, are detected during cornering with the respective wheel load of at least two wheels corresponding first state variables from which representing reference values are determined and compared with each other. Here, especially on the suspension measurable spring travel or spring pressures, z. B. also used adjustments of the shock absorber, a damper pressure or an internal tire pressure. Such methods also attempt to directly detect a change of the vehicle during cornering via sensors.

The DE 10 2004 058 791 A1 describes a method for determining the center of gravity height of a vehicle, in which a pitch dynamic quantity for representing the pitching behavior of the vehicle is determined and from this the center of gravity height is estimated.

The DE 112 006 003 274 B4 describes a method of determining the relative center of gravity height in a vehicle in which candidate estimates of the relative center of gravity height are determined and from which a vehicle dynamics condition is estimated. The vehicle dynamics behavior of the vehicle is measured here and compared with the candidate estimates of the relative center of gravity height to subsequently use the candidate estimate that provided the best results as the relative center of gravity height. Thus, the relative center of gravity height is ultimately estimated and compared with model values.

The EP 1 597 555 B1 describes a method for estimating the center of gravity height of a vehicle in which wheel loads of the vehicle wheels are measured, further determining a vehicle longitudinal acceleration, and measuring a vehicle tilt angle in the longitudinal direction by a sensor. Here, measured values are used during a standstill of the vehicle and during vehicle operation and compared with models.

The EP 1 680 315 B1 shows a method for stabilizing the tilting of a vehicle in critical driving situations, in which a vehicle center of gravity is estimated by means of an algorithm, is determined at an estimated driving speed, a ratio of the wheel contact forces against lying wheels when cornering. Here, the vehicle mass is estimated in particular and determined by the Radlastsensoren a ratio of the wheel contact forces of the opposite wheels. Wheel load sensors of sufficient accuracy are thus required for this method.

The EP 2 069 171 B1 describes a method for center of gravity estimation of a vehicle in which a lateral acceleration and a rolling rate or a roll angle of the vehicle is determined at different times during a journey and a differential angle of the inclination of the vehicle body in this period or at these times is determined, from which estimates the angular velocity of the tilt and from this the center of gravity can be determined. For such methods are sufficiently accurate measurements of the roll angle or the roll rate, ie the inclination of the vehicle about its longitudinal axis while driving required.

The US 201259536 A1 describes a method in which the rate of rotation of the vehicle is determined around its three axes and the vehicle mass is estimated. From the accelerations of the vehicle along its three axes and the rotation rates around the three axes, a model is used to estimate the center of gravity height.

The DE 10 2005 062 285 A1 describes a method for estimating the centroid issue of a vehicle in which operating state quantities such as lateral acceleration and / or yaw rate of the vehicle are determined and roll motions are determined by estimating the behavior of the air springs, wherein thermodynamic considerations are made about the behavior of the air volume in the air springs ,

Such methods are thus based either on rough estimates or on the use of special sensors for measuring z. As the inclination of the structure with respect to the road surface during cornering, or a very accurate measurement of the wheel loads. However, such sensors are either very costly or provide only relatively inaccurate values.

The invention has for its object to provide a method for determining a center of gravity of a vehicle, which allows a determination of a center of gravity height with relatively little effort. Furthermore, a method for driving dynamics control and a vehicle dynamics control system are to be created.

This object is achieved by a method according to claim 1, a method for driving dynamics control according to claim 14 and a vehicle dynamics control system according to claim 16. Furthermore, a vehicle is provided with such a vehicle dynamics control system. The dependent claims describe preferred developments.

Thus, the center of gravity height of the vehicle is determined from the behavior of longitudinal acceleration on an axle during cornering, i. H. longitudinal acceleration on a right longitudinally accelerated wheel and a left longitudinally accelerated longitudinal acceleration axis wheel; Preferably, another axis, in particular all other axes are not longitudinally accelerated.

Longitudinal acceleration setting values inputted to the longitudinally accelerated wheels are in a certain ratio for carrying out calculations hereunder, in particular a quotient formation in which some variables are omitted; preferably, the longitudinal acceleration adjustment values on the right longitudinally accelerated wheel and the left longitudinally accelerated wheel of the longitudinally accelerated axis.

According to a particularly preferred embodiment, the longitudinal acceleration is a braking, d. H. a negative longitudinal acceleration; Thus, the längsbeschleungte axis or detection axis is a braked axle, with braked wheels. As the longitudinal acceleration adjustment value, the brake pressure is preferably used.

In this case, therefore, the longitudinal acceleration and in particular the brake pressure on the left-hand braked wheel and the right-hand braked wheel can be the same.

Alternatively to braking, the longitudinal acceleration can also be a drive, d. H. a positive longitudinal acceleration. Thus, the longitudinally accelerated axis is a drive axle, and the longitudinally accelerated wheels are driven; the longitudinal acceleration adjustment value is preferably the input drive torque. When a differential is mounted on the driven axle, the same drive torque is input thereto to both driven wheels, so that the longitudinal acceleration adjustment values on the driven axle are the same.

As driving dynamics values are preferably a transverse dynamics of the vehicle descriptive transverse dynamics size, in particular the lateral acceleration itself or the yaw rate, and a slip behavior or Reibwertverhalten the longitudinally accelerated wheels, in particular the wheel slippage of the longitudinally accelerated wheels determined.

In order to be able to record the relevant measured variables and to compare them with each other, advantageously takes place while driving in a stable state, d. H. in particular without skidding or tilting tendency, preferably also without blocking and without or before driving dynamics intervention of a vehicle dynamics control system, a longitudinal acceleration, d. H. According to the first embodiment, braking the braked axle and non-braking another, unbraked axle. During the braking of the braked axle, the same brake pressure is advantageously applied to the left-hand wheel brake of the left-hand wheel and the right-hand wheel brake of the right-hand wheel.

In the embodiment with positive longitudinal acceleration, the driven axle is driven accordingly, preferably by means of differential; Preferably, in this case a drive torque is selected, which leads to a significant wheel slip.

In this case, an equilibrium of forces and torque equilibrium during cornering are preferably considered.

Thus, some advantages are achieved:
Thus, a determination or estimation of the center of gravity height of the vehicle is already possible in principle with relatively few measured variables or sensor data. In particular, z. For example, no inclination sensors for directly measuring a bank or roll inclination, or a sensor for measuring a roll rate may be required.

Advantageously, the inclusion of wheel loads or a measurement of the dormant on the respective wheels of the axle loads, preferably also the total mass of the vehicle is not required.

Advantageously, the ascertained center of gravity height can be continuously updated, in particular with continuous measurement of wheel slippage and the transverse dynamic behavior. Thus, current values can be provided and continuously improved or determined with smaller tolerances.

The wheel slippage, d. H. the left wheel slip of the left longitudinally accelerated wheel and the right wheel slip of the right longitudinally accelerated wheel of the considered here, while cornering along accelerated axis, this can on the one hand from existing control systems such. B. an ABS can be removed directly; Furthermore, the left wheel slip and right wheel slip of the longitudinally accelerated axis can also be done from a comparison with a non-longitudinally accelerated axis whose wheel speed allow the determination of Radumfangsgeschwindigkeiten without slippage, so that the slip from a comparison z. B. the two left wheels and accordingly from a comparison of the two right wheels, each of the longitudinally accelerated and not longitudinally accelerated axis, can take place.

The equilibrium of forces may refer in particular to the gravitational force acting on the center of gravity of the vehicle and the wheel contact forces of the left wheel and of the right wheel of the longitudinally accelerated axle that counteract each other or correspond in magnitude to the gravitational force.

The torque balance may relate in particular to a center which is located centrally between the wheel contact surfaces of the longitudinally accelerated wheels on the road, in particular below the center of gravity. Thus already accounts for a moment contribution of gravity, since it does not attack under any lever arm or their lever arm can be set as zero; Furthermore support moments of Radaufstandskräfte can be attached to this center with the same lever arm, namely half of the known track. Another contributing factor to moment equilibrium is the rolling momentum, which acts on the curve during cornering and uses a lever arm that represents the center of gravity to be determined.

Unlike known methods, the rolling moment is thus advantageously not compared with the outer wheel contact surface and thus the actual tilting movement, but against this midpoint between the left wheel contact surface and right wheel contact surface, as this results in some mathematical advantages.

The wheel contact forces can advantageously be estimated via longitudinal accelerations, in particular braking or driving forces; In this case, in particular, a relationship between wheel contact force and longitudinal acceleration or braking or driving force can be set above the coefficient of friction, wherein the coefficient of friction can be set in relation to the wheel slip.

In the embodiment with negative longitudinal acceleration, by setting the brake pressure at the left wheel of the left braked wheel and the right wheel of the right wheel braked equal, their braking forces can be set equal so that differences in left slip and right slip on the differences in can be attributed to the coefficients of friction; By quotient formation, a contribution of the wheel loads can thus be shortened.

The same is done in the embodiment with positive longitudinal acceleration, in the right and left the same drive torques are entered.

Thus, wheel-wise direct relations or relatively accurate estimates can be used to arrive at a system of equations in which the center of gravity height can be determined independently of the wheel loads of the left wheel and the right wheel. Advantageously, the center of gravity height here from z. Example, a vehicle parameter such as the track width, the determined wheel slippage of the left longitudinally accelerated and right longitudinally accelerated wheel of the longitudinally accelerated axis and a transverse dynamics variable, in particular the lateral acceleration, are determined directly.

The method may, for. B. alternately performed for the multiple axes, so that z. B. temporarily braked the front axle and the rear axle is unbraked and vice versa, preferably in driving conditions of a curve without spin, without (or before) engaging a vehicle dynamics control system and advantageously even with sufficiently stable friction, so that z. B. a relationship between wheel slip and coefficient of friction, in particular a linear relationship, can be set.

Here, the embodiments of the negative and positive longitudinal acceleration can also be combined, so that the method on the multiple axes z. B. can be performed by one or more axles are braked alternately, and the drive axle is accelerated without braking on another axis. Furthermore, z. B. the drive shaft are alternately accelerated and braked without involving the other axes, so that from this comparison can be made.

The method according to the invention for determining a center of gravity height can subsequently be used in particular in a driving dynamics control method, in particular for stabilizing against lateral tilting tendencies, but also for stabilizing against pitch or tipping inclinations about the transverse axis. It turns out that this results in particular synergistic advantages, since in the method according to the invention for determining the center of gravity basically known vehicle parameters such as the track width and dynamically very precisely ascertainable values such as wheel slippage of the left wheel and the right wheel of a longitudinally accelerated axis are used, and Furthermore, a variable describing the transverse dynamics, such as the lateral acceleration and / or the yaw rate, can be measured with little sensor effort.

Thus, in particular a critical lateral acceleration can be determined from the center of gravity height, then z. B. can adjust the vehicle control system.

The vehicle control system according to the invention can thus be formed from the wheel speed sensors which output the wheel speeds as wheel speed signals, a measuring device or a sensor for measuring a transverse dynamics quantity such as the lateral acceleration or the yaw rate and output of a transverse dynamics measurement signal, and a control device , where as vehicle parameters z. B. enters only the track width. The control device preferably receives the wheel speed signals and the transverse dynamics measurement signal, possibly also further signals from an in-vehicle data system, and controls with adjustment signals longitudinal acceleration control devices. To set a negative longitudinal acceleration thus brake signals are output to wheel brakes as setting signals to set a positive longitudinal acceleration are thus output as adjustment signals drive torque request signals, z. B. to an engine control unit that then drives the driven axle accordingly.

The vehicle control system according to the invention is thus provided in particular for carrying out a method according to the invention.

The invention is explained in more detail below with reference to an embodiment which relates to the first embodiment of the negative longitudinal acceleration and can be correspondingly transferred to the second embodiment of the positive longitudinal acceleration.

1 a vehicle with a vehicle dynamics control system according to an embodiment of the invention when cornering in section;

2 the vehicle off 1 in plan view,

3 a flow chart of the method according to the invention.

A vehicle 1 drives on a roadway 2 , The vehicle 1 In particular, a truck may be and is here biaxially formed with a front axle VA and a rear axle HA, wherein a same track width s for the front axle VA with right front wheel VA-r and left front wheel VA-l and the rear axle HA with right rear wheel HA-r and left rear wheel HA-l is to set. The vehicle 1 drives here in a left turn with a driving speed v and a lateral acceleration a.

The vehicle 1 has a (total) mass m, which is represented in the usual kinematic considerations by the position of its center of gravity SP. The center of gravity SP is at a center of gravity hs above the roadway 2 is arranged and is idealized in the middle positioned with respect to the transverse direction y. The center of gravity SP is thus centered on the axes VA and HA.

The center of gravity SP thus has a - initially unknown and to be determined - center of gravity hs. According to 1 is still considered the front axle VA, the situation is the rear axle HA accordingly. Thus, a left wheel contact surface LA of the left front wheel VA-l and a right wheel contact surface RA of the right front wheel VA-r are each idealized with respect to their centers, so that the left wheel contact surface LA and the right wheel contact surface RA each in the transverse direction y a distance s / 2 from a midpoint M lying midway between them. The center M thus also lies on a center axis of the projection of the vehicle 1 on the road 2 , The center of gravity SP is above, ie offset in the Z direction, the center M and offset in the longitudinal direction (x direction). The exact longitudinal position of the center of gravity SP is not considered here.

The vehicle 1 also has wheel speed sensors 3a . 3b . 3c and 3d ascertain the wheel speeds na, nb, nc and nd and to a driving dynamics control device 4 which determines from the wheel speeds na, nb, nc, nd wheel peripheral speeds va, vb, vc, vd of the wheels VA-1, VA-r, HA-1, HA-r. Such investigations are known in particular for ABS systems (antilock braking system), as well as EBS systems (electronic brake system). In the following, such wheel peripheral speeds are generally referred to as reference speed vref, which correspond to the driving speed v when driving without slipping.

In the embodiment shown is a single vehicle 1 , in particular a truck, shown; The inventive method can be carried out separately for each of the vehicles in a vehicle combination of several vehicles, ie in particular towing vehicle and trailer.

The vehicle 1 according to the embodiment shown also has a provided in the vehicle center of gravity SP or approximately in this position lateral acceleration sensor 5 for determining the lateral acceleration a; Alternatively, as shown by dashed lines, a yaw rate sensor can also be used 5a - z. B. outside of the center of gravity SP - be provided which measures a yaw rate ω and from the yaw rate ω and the vehicle speed v determines the lateral acceleration a.

Thus, a driving dynamics control system 12 formed, which is the driving dynamics control device 4 , the lateral acceleration sensor 5 , the wheel speed sensors 3a . 3b . 3c and 3d and wheel brakes 6a . 6b having.

• B1) Kurvenfahrt, d. h. a ≠ 0, wobei auch ein Linkwinkelsignal gemessen werden kann,
• B2) kein Eingriff des Regelsystems, folgende Maßnahmen durchgeführt werden:
• C1) eine Achse, z. B. die Hinterachse HA bleibt vollständig ungebremst,
• C2) die andere Achse, z. B. die Vorderachse VA, wird an ihren Rädern, also dem linken Vorderrad VA-l und dem rechten Vorderrad VA-r, mit gleichem Bremsdruck p gebremst, d. h. der linken Radbremse 6a am linken Vorderrad VA-l wird der gleiche Bremsdruck p zugeführt wie der rechten Radbremse 6b am rechten Vorderrad VA-r,
• C3) die Raddrehzahlen na, nb, nc, nd und die Querbeschleunigung a werden gemessen und in der Fahrdynamik-Steuereinrichtung 4 verarbeitet, zusammen mit der als Fahrzeugparameter bekannten Spurbreite s.

While driving the vehicle 1 provides brake management of the vehicle dynamics control device 4 , ie a corresponding programming of the vehicle dynamics control method of the vehicle dynamics control device 4 , for that at least temporarily, preferably under the conditions:

• B1) cornering, ie a ≠ 0, whereby a link angle signal can also be measured,
• B2) no intervention of the control system, the following measures are carried out:
• C1) an axis, z. B. the rear axle HA remains completely unbraked,
• C2) the other axis, z. As the front axle VA is at their wheels, so the left front wheel VA-l and the right front wheel VA-r, braked with the same brake pressure p, ie the left wheel brake 6a on the left front wheel VA-l the same brake pressure p is supplied as the right wheel brake 6b on the right front wheel VA-r,
• C3) the wheel speeds na, nb, nc, nd and the lateral acceleration a are measured and in the driving dynamics control device 4 processed, together with the known as vehicle parameters track width s.

This situation can be adjusted, at least temporarily, preferably in succession with a once braked front axle VA and non-braked rear axle HA and subsequently vice versa, especially in the case of a curve situation recognized as uncritical, in which the lateral acceleration a is not too large and no spin behavior is detected.

The following is according to 1 Considering the braked front axle VA First, a left wheel slip λa of the left front wheel VA-1 and a right wheel slip λb of the right front wheel VA-r are determined. This can be done in particular by a page-by-side comparison of the front axle VA and rear axle HA:

For the left front wheel VA-1, the left wheel slip λa is determined from: λa = (vc - va) / vc GL1

For the right front wheel VA-r, the right wheel slip λb is determined from: λb = (vd -vb) / vd GL2

Subsequently, the in 1 shown balance of power applied, after which on the vehicle 1 In the vertical direction z, the gravitational force or gravitational force m · g acts on the center of gravity SP and on the wheel contact forces, ie the left wheel contact force Gl and the right wheel contact force Gr (or the roadway 2 applied counter-forces) is caught. The result is the equation GL3 Gl + Gr = m × g GL3

This consideration is thus relevant to the vertical Z direction, i. H. without consideration of the centrifugal force m · a acting in the transverse direction y, which is thus perpendicular to the gravitational force or gravitational force m · g. Even further considerations taking into account the centrifugal force m · a lead only to the fact that in the left-hand bend that the outside wheel, so the right front wheel VA-r, loaded and the inside wheel, so thus the left front wheel VA-l, is relieved, but the total Radaufstandskraft sum Gl + Gr remains unchanged.

Furthermore, the moment equilibrium around the center M is considered: Gl · (s / 2) + m · a · hs = Gr · (s / 2) GL4

Gl·(s/2)

das linke Stützmoment, also Produkt aus linker Radaufstandskraft Gl und Hebelarm s/2,

m·a·hs

das angreifende Wankmoment, also Produkt aus Fliehkraft m·a und dem Hebelarm, hier also der Schwerpunktshöhe hs, und

Gr·(s/2)

das rechte Stützmoment, also Produkt aus rechter Radaufstandskraft Gr und dem Hebelarm s/2.

Here is:

Gl · (s / 2)

the left support moment, ie product of left wheel contact force Gl and lever arm s / 2,

m * a * hs

the attacking rolling moment, ie the product of centrifugal force m · a and the lever arm, in this case the center of gravity height hs, and

Gr · (S / 2)

the right supporting moment, ie product of the right wheel contact force Gr and the lever arm s / 2.

An essential advantage of this torque formation is also the fact that the longitudinal position, ie in the x-direction, also provides no moment contribution here.

Thus, it is irrelevant that the center of gravity SP is not in the drawing plane of 1 lies.

Hereinafter, the wheel contact forces Gn and Gr existing in the above equations are related to the braking forces, that is, the left brake force Fb-1 of the left front wheel Vl and the right brake force Fb-r of the right front wheel VR.

Since the same brake pressure p is built up on the left and on the right, the left-hand braking force Fb-1 and the right-hand braking force Fb-r must be set the same way: Fb-1 = Fb-r GL5a

In general, braking forces Fb are proportional to the wheel loads or wheel contact forces G with sufficiently stable travel and not too great slip, ie a braking force Fb can be represented as the product of a wheel contact force G and a coefficient of friction μ, ie here Fb-1 = μl. Eq Fb-r = μr * Gr GL5b with the left friction coefficient μl and the right friction coefficient μr.

Thus, equation GL5 holds Fb-1 = Fb-r → μl * Gl = μr * Gr GL5

Hereinafter, a relationship between the coefficients of friction, that is, the left friction coefficient μl and the right friction coefficient μr, respectively, is set with the left slip λl and the right slip λr, respectively:
for the stable region of the μ-λ curve, a linear relationship results, ie μ = K · λ with a constant linearity factor K. Thus, the equations GL6 apply: μl = K · λl and μr = K · λr GL6

Thus, the equations GL5 and GL6 give the following equation GL7: λl · Gl = λr · Gr or Gl = (λr / λl) · Gr GL7

From equation GL3, the following equation GL8 follows: m = (G1 + Gr) / g GL8

Substituting now equations GL7 and GL8 into equation GL4, the following equation 9 results:

This equation 9 is independent of the left wheel load Gl and the right wheel load Gr; the center of gravity height hs follows from the following equation 10:

Thus, the center of gravity height hs can be estimated from the determined wheel slippage, i. H. the right wheel slip λr and the left wheel slip λl, the track width s and the lateral acceleration a.

• B1) Kurvenfahrt, d. h. a ≠ 0,
• B2) kein Eingriff des Regelsystems, die folgenden Maßnahmen durchgeführt werden:
• C1) eine Achse, z. B. die Hinterachse HA bleibt vollständig ungebremst,
• C2) die andere Achse, z. B. die Vorderachse VA, wird an dem linken Vorderrad VA-l und dem rechten Vorderrad VA-r mit gleichem Bremsdruck p gebremst, dann werden in Schritt St2
• C3) die Raddrehzahl-Signale Sna, Snb, Snc, Snd der Raddrehzahlsensoren 3a, 3b, 3c und 3d aufgenommen, hieraus die Raddrehzahlen na, nb, nc, nd entnommen, und die Querbeschleunigung a gemessen und hieraus das Querbeschleunigungs-Messsignal S2 an die Fahrdynamik-Steuereinrichtung 4 ausgegeben,

in Schritt St3 werden dann
in der Fahrdynamik-Steuereinrichtung 4 diese Messdaten verarbeitet, zusammen mit der als Fahrzeugparameter bekannten Spurbreite s,
wobei vorzugsweise in Schritt St3a
gemäß Gleichung GL1 die Radschlupfe λl und λr
ermittelt werden, und in Schritt St3b
die Schwerpunkthöhe hs aus Gleichung GL10 ermittelt wird.The inventive method thus provides according 3 following steps:
After the start in step St0, in step St1
in the above conditions

• B1) cornering, ie a ≠ 0,
• B2) no intervention of the control system, the following measures are carried out:
• C1) an axis, z. B. the rear axle HA remains completely unbraked,
• C2) the other axis, z. B. the front axle VA, is braked at the left front wheel VA-l and the right front wheel VA-r with the same brake pressure p, then in step St2
• C3) the wheel speed signals Sna, Snb, Snc, Snd of the wheel speed sensors 3a . 3b . 3c and 3d taken from this, the wheel speeds na, nb, nc, nd taken, and measured the lateral acceleration a and from this the lateral acceleration measurement signal S2 to the vehicle dynamics control device 4 output

then in step St3
in the vehicle dynamics control device 4 processed these measured data, together with the known as vehicle parameters track width s,
preferably in step St3a
according to equation GL1 the wheel slippage λl and λr
are determined, and in step St3b
the center of gravity height hs is determined from equation GL10.

Subsequently, in a step St4 from the center of gravity height hs, preferably in addition to the track width s, a critical lateral acceleration a-crit can be determined from which tipping over threatens, and then in step St5 a driving dynamics control method are made, in particular a control method at be taken into account the tilting inclinations of the vehicle, in particular a tipping to the side, possibly also a Nick-behavior (diving), d. H. a pitch or dip during braking in the longitudinal direction.

LIST OF REFERENCE NUMBERS

1

vehicle

2

roadway

3a, 3b, 3c and 3d

wheel speed sensors

4

Vehicle dynamics control means

5

Lateral acceleration sensor

50

Yaw rate sensor

6a

left wheel brake on the left front wheel VA-l

6b

right wheel brake on the right front wheel VA-r

12

Vehicle control system

S1

Brake signal;

S1a

first brake signal to wheel brake 3a

S1b

second brake signal to wheel brake 3b

S 1 d

third brake signal to wheel brake 3c

S 1 d

fourth brake signal to wheel brake 3d

S2

Lateral acceleration measurement signal

n / A

first wheel speed

nb

second wheel speed

nc

third wheel speed

nd

fourth wheel speed

sna

first wheel speed signal of the wheel speed sensor 3a

snb

second wheel speed signal of the wheel speed sensor 3b

Snc

third wheel speed signal of the wheel speed sensor 3d

snd

fourth wheel speed signal of the wheel speed sensor 3d

v

driving speed

a

lateral acceleration

ω

yaw rate

p

brake pressure

VA

Front

HA

rear axle

VA-r

right front wheel

VA-l

left front wheel

HA-r

right rear wheel

HA-l

left rear wheel

SP

main emphasis

m

Dimensions

s

gauge

s / 2

Distance from a midpoint M

hs

Gravity height

x

x-direction, longitudinal direction

y

Y direction, transverse direction

z

Z direction, vertical direction

LA

left wheel contact surface of the left front wheel VA-l

RA

right wheel contact surface of the right front wheel VA-r

M

Focus

va, vb, vc, vd

wheel peripheral

λa

left wheel slip of the left front wheel VA-l

.lambda..sub.B

right wheel slip of the right front wheel VA-r

gl

left wheel lift

Gr

right wheel-upforce

m · a

centrifugal

m · g

gravity

GI + Gr

Wheel contact-sum

Gl · (s / 2)

left support moment

m * a * hs

attacking roll moment

Gr · (S / 2)

right support moment

Fb-l

left braking force of the left front wheel Vl

Fb-r

right braking force of the right front wheel VR.

μ

friction

ul

left coefficient of friction

ĩr

right coefficient of friction

λl

left slip

.lambda.r

right slip

K

constant linearity factor

St0 to St5

Steps of the procedure

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

• US 2012/0173133 A1 [0006]
• DE 10053605 B4 [0007]
• DE 10247993 B4 [0008]
• DE 19904216 A1 [0009]
• DE 102004058791 A1 [0010]
• DE 112006003274 B4 [0011]
• EP 1597555 B1 [0012]
• EP 1680315 B1 [0013]
• EP 2069171 B1 [0014]
• US 201259536 A1 [0015]
• DE 102005062285 A1 [0016]

Claims (20)

Method for determining a center of gravity height (hs) of a vehicle ( 1 ), in particular a commercial vehicle, in which during cornering of the vehicle ( 1 ) longitudinally accelerated wheels (VA-l, VA-r) of a longitudinally accelerated axle (VA) of the vehicle ( 1 ) are longitudinally accelerated with longitudinal acceleration setting values (p) which are in a predetermined relationship to each other (St1), driving dynamics values (na, nb, nc, nd, v, ω, a) are determined, the driving dynamics values (na , nb, nc, nd, v, ω, a) a transverse dynamics quantity (a, ω) describing lateral dynamics of the vehicle and a slip behavior or friction behavior of the longitudinally accelerated wheels (VA-r, VA-r) of the longitudinally accelerated axis ( VA) comprise descriptive slip quantities (λr, λl), (St2) and from the driving dynamics values (na, nb, nc, nd, v, ω, a) and from an equilibrium of forces and moment equilibrium during cornering a center of gravity height (hs ) is determined (St3). A method according to claim 1, characterized in that the longitudinal acceleration setting values (p) at the longitudinally accelerated wheels (VA-l, VA-r) are equal to the longitudinally accelerated axis (VA). A method according to claim 1 or 2, characterized in that unaccelerated wheels (HA-r, HA-l) at least one unaccelerated axis (HA) of the vehicle ( 1 ), preferably all other axles of the vehicle ( 1 ), are unaccelerated (St1). A method according to claim 3, characterized in that the slip quantities (λr, λl) from comparing the slip behavior and / or Reibwertverhaltens - a left longitudinally accelerated wheel (VA-l) of the longitudinally accelerated axis (VA) with a left not longitudinally accelerated wheel (HA-r) of the non-longitudinally accelerated axis (VA) and a right longitudinally accelerated wheel (VA-r) of the longitudinally accelerated axis (VA) with a right non-longitudinally accelerated wheel (HA-r) of the non-longitudinally accelerated axis (VA) during cornering be determined (St3a). A method according to claim 4, characterized in that as slip sizes (λr, λl) Radschlupfe (λr, λl) of the longitudinally accelerated wheels (VA-r, VA-l) of the longitudinally accelerated axis (VA) are determined from determined wheel speeds (na, nb) of the longitudinally accelerated wheels (VA-r, VA-l) and reference speeds (vc, vd) consisting of wheel speeds (nc, nd) of the non-longitudinally accelerated wheels (HA-r, HA-l) of the non-longitudinally accelerated axle (HA) be determined. Method according to one of the preceding claims, characterized in that as transverse dynamics quantity (a, ω) a lateral acceleration (a) and / or a yaw rate (ω) of the vehicle ( 1 ) is measured or determined. Method according to one of the preceding claims, characterized in that at the balance of forces and the moment equilibrium during cornering in the center of gravity (SP) of the vehicle ( 1 ), preferably in the transverse direction pointing centrifugal force (m · a), one in the center of gravity (SP) of the vehicle ( 1 ) and gravitational forces (Gl, Gr) of the longitudinally accelerated wheels (VA-r, VA-l) of the vehicle ( 1 ). A method according to claim 7, characterized in that when taking the balance of forces, a gravitational force (m · g) and applied by the left longitudinally accelerated wheel (VA-l) and the right longitudinally accelerated wheel (VA-r) applied wheel contact forces (Gl, Gr) and the moment balance is set around a mid-point (M) on the road ( 2 ) between the wheel contact surfaces (LA, RA) of the longitudinally accelerated wheels (VA-r VA-l), preferably centrally between between the wheel contact surfaces (LA, RA) and below the center of gravity (S). A method according to claim 8, characterized in that in the moment equilibrium the following moments are related: a rolling moment, which results from a centrifugal force (m · a) acting on the center of gravity (SP) and the center of gravity (hs), and at the center (M) starting, formed from the wheel contact forces (Gl, Gr) of the longitudinally accelerated wheels (VA-r, VA-l) supporting moments (Gl s / 2, size / 2), preferably without a moment contribution to the center of gravity ( SP) acting gravitational force (m · g). Method according to one of claims 7 to 9, characterized in that, taking into account the Reibwertverhalten or slip behavior of the longitudinally accelerated wheels (VA-r, VA-l) - Relationships between braking forces (FB-l, FB-r), Radaufstandkräften (Gl, Gr ) and friction coefficients (μl, μr) of the longitudinally accelerated wheels (VA-r, VA-l) and - a dependence of the coefficients of friction (μl, μr) on the wheel slips (λr, λl) of the longitudinally accelerated wheels (VA-r, VA-l ) are used. Method according to one of the preceding claims, characterized in that a dependence of the center of gravity height (hs) of the vehicle ( 1 ) is determined independently of the wheel loads (Gl, Gr) on the longitudinally accelerated wheels (VA-r, VA-l) and the non-longitudinally accelerated wheels (HA-l, HA-r) and / or a vehicle mass (m). Method according to one of the preceding claims, characterized in that the center of gravity height (hs) is determined from only the following to be determined driving dynamics values and vehicle parameters: right wheel slip (λr) of the right longitudinally accelerated wheel (VA-r), left wheel slip (λl ) of the left longitudinally accelerated wheel (VA-r), track width (s) of the longitudinally accelerated axis (VA), and lateral dynamics magnitude (a, ω), e.g. B. lateral acceleration. A method according to claim 12, characterized in that the center of gravity height (hs) is determined from the equation:

with hs center of gravity, λl inner wheel slip, λr outer wheel slip, g gravitational acceleration, s track width, a lateral acceleration. Method for driving dynamics control of a vehicle ( 1 ), in which a center of gravity (hs) of the vehicle (hs) 1 ) is determined by a method according to one of the preceding claims and subsequently the driving dynamics control of the vehicle ( 1 ) is performed as a function of the determined center of gravity height (hs). A method according to claim 14, characterized in that the determined center of gravity height (hs) for determining a critical lateral acceleration (a-crit) of the vehicle ( 1 ) and / or lateral instability. Method according to one of the preceding claims, characterized in that the longitudinally accelerated axis (VA) of the vehicle ( 1 ) is a braked axle (VA), wherein the longitudinally accelerated wheels (VA-l, VA-r) are braked and the longitudinal acceleration setting values are brake pressures (p). A method according to claim 16, characterized in that the non-longitudinally accelerated wheels (HA-r, HA-l) are unbraked wheels of an unbraked axle. Method according to one of claims 1 to 15, characterized in that the longitudinally accelerated axis (VA) of the vehicle ( 1 ) is a driven axle (VA), wherein the longitudinally accelerated wheels (VA-l, VA-r) are driven and the longitudinal acceleration setting values are drive torques, wherein the non-longitudinally accelerated wheels (HA-r, HA-l) are not driven. Driving dynamics control system ( 12 ), in particular for carrying out a method according to one of claims 1 to 18, comprising: wheel speed sensors ( 3a . 3b . 3c . 3d ) for determining wheel speeds (na, nb, nc, nd) and output of wheel speed signals (Sna, Snb, Snc, Snd), adjusting devices ( 6a . 6b ) for the longitudinal acceleration of longitudinally accelerated wheels (VA-l, VA-r) of a longitudinally accelerated axle (VA), a lateral acceleration measuring device ( 5 . 50 ) for determining a lateral acceleration measured variable (q, ω) and output of a lateral acceleration measuring signal (S2), a driving dynamics control device ( 4 ) for receiving the wheel speed signals (Sna, Snb, Snc, Snd) and the lateral acceleration measuring signal (S2) and outputting actuating signals to the adjusting devices ( 6a . 6b ) wherein the driving dynamics control device ( 4 ) is designed such that during cornering of the vehicle ( 1 ) the actuating signals (S1, S1a, S1b, S1c, S1d) to the actuating devices ( 6a . 6b ) for the longitudinal acceleration of longitudinally accelerated wheels (VA-l, VA-r) of a longitudinally accelerated axle (VA) of the vehicle ( 1 ) for setting longitudinal acceleration adjustment values (p) on the longitudinally accelerated wheels (VA-1, -VA-r), wherein the longitudinal acceleration adjustment values (p) are in a predetermined relationship to one another, wherein the driving dynamics control device ( 4 ) is further adapted to determine driving dynamics values (na, nb, nc, nd, v, ω, a) which determine a transverse dynamics of the vehicle and a slip behavior and / or coefficient of friction behavior of the longitudinally accelerated wheels (VA-r, VA). r) and to determine a center of gravity height (hs) from the driving dynamics values (na, nb, nc, nd, v, ω, a) and from an equilibrium of forces and moment equilibrium during cornering. Vehicle ( 1 ) with a vehicle dynamics control system ( 12 ) according to claim 19 and at least two axes (VA, HA), of which at least one axis is a longitudinally accelerated axis (VA) with longitudinally accelerated wheels (VA-l, VA-r).

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