DE102009050777A1 - Method for determining parameter characterizing motor vehicle or condition of vehicle, involves determining control parameter influencing driving direction of motor vehicle, where parameter regulates steered wheel of vehicle - Google Patents

Abstract

The method involves determining a control parameter (17) e.g. electric current, influencing a driving direction of a motor vehicle (1), where the parameter regulates a steered wheel of the vehicle. Electric steering moment (11) acting on the wheel is determined based on the parameter. Manual steering moment (13) generated by a driver of the vehicle is determined using a measurement device (15). Lateral force (19) acting on the wheel is determined based on the steering moments. A parameter characterizing the vehicle or a condition of the vehicle is determined based on the control parameter. An independent claim is also included for a motor vehicle including a device for influencing a driving direction of the vehicle.

Description

The The invention relates to a method for determining at least one Motor vehicle or a state of the motor vehicle characterizing Size.

Methods for determining a size are known. For example, it may be a measurable variable, an indirectly measurable variable, or a state variable that is not directly measurable. From the DE 103 07 848 A1 For example, a method for determining a motion state of a traffic object in the vicinity of a vehicle is known. The traffic object may likewise be a motor vehicle. As measured variables, an acceleration of the vehicle, a relative distance between the vehicle and the traffic object and at least one speed variable are measured or determined. In a computing unit, at least one variable describing the longitudinal dynamics of the traffic object is calculated as state variable according to a mathematical observer model.

task The invention is an improved determination of at least one a motor vehicle or a condition of the motor vehicle characterizing size to enable, in particular, an improved determination of the state.

The Task is in a method for determining at least one Motor vehicle or a state of the motor vehicle characterizing Size through the steps of finding one Driving direction of the motor vehicle influencing control variable and Determine the size depending on the tax size solved. Advantageously in a driving operation of the motor vehicle or for operating the Motor vehicle anyway necessary control variable measured or to be tapped in order depending on this to determine the desired size. Advantageous No additional measuring sensor is required by the size depending on the control size too determine. It is advantageous only a corresponding measuring section for determining and processing the tax quantity necessary. The as input of the measuring section serving tax code falls during operation the motor vehicle advantageously without further notice anyway. through the control variable becomes an operation of the motor vehicle necessary aggregate controlled. By means of the tax code a direction of travel of the motor vehicle is influenced or controlled, so the tax code is inevitable always present for guiding the motor vehicle.

at An embodiment of the method is the step of determining the tax size as one place at least a steered wheel of the motor vehicle by means of an electric Steering required electricity is provided. By means of the tax code is the electric steering for guiding the motor vehicle driven. The electric steering can corresponding electric motors, For example, have brushless electric motors. The control the electric steering can by means of a corresponding servo control or by means of a pilot control. In both cases can advantageously the electric current of the steering-driving Electric motor from a corresponding control of the electric motor be tapped. This can be a corresponding transfer behavior of the electric motor to be used by the current to an output to close the electric motor, in particular by means of a suitable transformation calculation.

at Another embodiment of the method is the step Determining one on the at least one steered wheel of the vehicle acting electric steering torque depending on the current provided. Advantageously, as an output variable the electric steering or one of the corresponding electric motor the electric steering the steering torque acting on the steered wheel be determined. It is possible to change the steering torque for only a single wheel, but preferred for pairwise cooperating To determine the wheels of an axle.

at Another embodiment of the method is the step Determining a manually generated by a driver of the vehicle Manual steering torque provided by means of a torque sensor. Depending on the design of the electric steering, it is possible this still, especially for security reasons, still a direct mechanical penetration on the at least one steered wheel has. In this case, there is at least one steered wheel the electric steering torque and in addition the manual steering torque applied by the driver using muscle power at.

In a further embodiment of the method, the step of determining a lateral force acting on the at least one wheel by means of a transmission behavior of the steering and in dependence on the manual and the electric steering torque is provided. Under the transmission behavior of the steering, the transmission behavior of the electric motor of the steering and / or a corresponding gear ratio of a steering gear of the electric steering can be understood. Together with a vehicle suspension or a known geometry corresponding handlebar for articulating the at least one steered wheel can be calculated from the total applied steering torque acting on the at least one side wheel force. In addition, it is conceivable to take friction of the electric steering into consideration term. If necessary, however, it is possible in a simplistic manner that the friction is negligibly small in comparison to the total steering torque that occurs and can therefore be ignored in the case of a corresponding calculation of the lateral force.

at Another embodiment of the method is the step Determine the size by means of a control variable or the measuring equation having lateral force calculating them intended. Advantageously, from the side force in the knowledge of others Parameter of the vehicle the size calculated depending on the tax rate or the resulting lateral force can be calculated. As calculation basis may be a corresponding model of the vehicle, for example a Serve single-track model of the motor vehicle.

at Another embodiment of the method is the step Determining the size as a vehicle yaw rate provided by the measurement equation. Advantageously, the measurement equation the vehicle yaw rate as the basis for a Determine the state of the motor vehicle serve. Is advantageous this measurement equation is additionally available and can be used in particular instead of a measurement equation, into which a yaw acceleration usually enters would have to be determined by differentiating. Advantageous occur when occurring in a differentiating signal interference or in a filtering phase disturbances not on.

at Another embodiment of the method is the step Determining one on front wheels and on rear wheels acting front side force and rear side force by means of the transmission behavior of the steering and in dependence provided by the manual and the electric steering torque. Advantageous the motor vehicle can be a front axle steering and a rear axle steering so that both the lateral force acting on the front wheels and determines the side force acting on the rear wheels can be.

at Another embodiment of the method is the step Determining a vehicle mass and a mass inertia of the vehicle as a function of the lateral forces intended. Advantageously, knowing the front Side force and rear side force using known physical The vehicle mass and the mass inertia are related be determined by calculation.

at Another embodiment of the method is the step Use the vehicle yaw rate determined by the measurement equation in a measurement vector of an observer and a Kalman filter provided for determining the condition of the vehicle. Advantageous can by means of the measurement equation of the vehicle yaw rate corresponding observer model or the Kalman filter due to vehicle yaw rate which can be determined by means of a high signal quality the condition of the vehicle with a particularly high quality determine.

The Task is also in a motor vehicle, set up, designed and / or designed to perform an advance solved described method. It results in the advance described advantages.

The The object is further achieved in a motor vehicle characterized that one controllable by means of a control variable Device for influencing a direction of travel of the motor vehicle is provided, depending on the control variable a motor vehicle or a state of the motor vehicle characterizing Size can be determined. Advantageously, the falls Control variable for driving the device at a Driving the motor vehicle anyway, with advantageous depending the size of the control size a high quality can be determined.

Further Advantages, features and details emerge from the following Description in which, where appropriate with reference to the Drawing - at least one embodiment is described in detail. Described and / or illustrated Characteristics form for themselves or in any other, more meaningful Combination the subject of the invention, optionally also independently from the claims, and in particular in addition also Be the subject of one or more separate applications. Same, similar and / or functionally identical parts are provided with the same reference numerals. Show it:

1 shows a schematic view of an electric steering of a motor vehicle.

1 shows a schematic view of a partially illustrated motor vehicle 1 with an electric steering 3 , The electric steering 3 has a human / machine interface 5 , For example, a steering wheel, on an electric support drive 7 and in a penetration on a Radanlenkung 9 the electric steering 3 acts. By means of the electrical support drive 7 can be an electrical steering torque 11 T _engine on the wheel steering 9 be supported. By means of the human / machine interface 5 a manual steering torque T _driver can be exercised that in a direct penetration on the wheel steering 9 acts. By means of a measuring device 15 can the manual steering torque 13 be measured, by means of the measuring device 15 measured manual steering torque 13 also the support drive 7 for setting a corresponding supporting electric steering torque 11 can be available. The support drive 7 is by means of a control variable 17 , For example, driven in the form of an electric current, which is adjusted by means of a control and / or regulating unit, not shown. The tax size 17 in the form of the electric current drives an electric motor, not shown, for example, a brushless electric motor of the electric steering 3 at. The wheel steering 9 represents a steering angle of the steered wheels of the motor vehicle 1 a, wherein at the steered wheels one of a current driving speed of the motor vehicle 1 and the adjusted steering angle dependent lateral force 19 results. Between the side force 19 and the tax quantity 17 there is a mathematically calculable relationship.

Advantageously, in knowledge of the control variable 17 the lateral force acting on the wheels 19 be determined.

The following is based on dynamic driving considerations for the motor vehicle 1 explains how the relationship between the tax size 17 and the lateral force 19 can be advantageously used to determine a measurement equation. Advantageous is in the form of electric steering 3 a sensor provided in addition to the motor vehicle, such as a lateral acceleration sensor, a longitudinal acceleration sensor, a yaw rate sensor, a steering wheel angle sensor and / or wheel speed sensors, a further measuring device for determining the lateral force 19 to disposal. This can be advantageous for determining a condition of the motor vehicle 1 , particular vehicle intrinsic movements, such as a slip angle and / or a vehicle lateral speed and the vehicle characteristic variables, such as a vehicle mass and / or a vehicle inertia and an environment of the motor vehicle indicative variables such as a road friction coefficient and / or road gradient are used. The variables mentioned are relevant for control systems of the motor vehicle not shown in detail 1 such as for a brake, for a chassis, for electric steering, driving stability regulations or driving stability regulations and / or driver assistance systems. So-called driving dynamics models are used in particular for driving dynamics regulations, for example in the form of linear or non-linear single-track or two-track models, which can be fed primarily with values of the aforementioned sensors, in particular lateral acceleration, longitudinal acceleration, yaw rate, steering wheel angle and / or wheel speeds. Advantageously, by the in 1 shown relationship between the taxable amount 17 and the lateral force 19 an additional measurement equation over the on the tires of the motor vehicle 1 attacking side force 19 be supported.

In the following, by way of example, with reference to a linear single-track model, which corresponds to the in 1 shown electric steering takes into account a vehicle dynamics model explained in more detail. Alternatively and / or additionally, it is conceivable, the approaches shown analogous to a multiple steering, so for example, a front-wheel steering and a rear axle of the motor vehicle 1 adapt.

t

= zeitlicher Verlauf

[k]

= Zeitschritte eines zeitdiskreten Systems

δ_L

= Lenkradwinkel

δ_V

= Lenkwinkel vorne

β(t)

= Schwimmwinkel

α_V(t)

= Schräglaufwinkel der Reifen an der Vorderachse

F_yV(t)

= Seitenkraft Vorderachse

A_H(t)

= Schräglaufwinkel der Reifen an der Hinterachse

c_αH

= wirksame Schräglaufsteifigkeit der Reifen an der Vorderachse

F_yH(t)

= Seitenkraft Hinterachse

c_αH

= wirksame Schräglaufsteifigkeit der Reifen an der Hinterachse

a_YSens

= die von einem Sensor gemessene Querbeschleunigung

a_Yquer

= Querbeschleunigungsanteil aus der Radialkraft

a_Ygravi

= Querbeschleunigungsanteil aus der gravimetrischen Kraft

v_x(t)

= Fahrzeuglängsgeschwindigkeit

v_y(t)

= Fahrzeugquergeschwindigkeit

v_x(t)

= Fahrzeugreferenzgeschwindigkeit (typ. aus Raddrehzahlen ermittelt)

Ψ'(t)

= Fahrzeuggiergeschwindigkeit

Ψ''(t)

= Fahrzeuggier'beschleunigung

m_Fzg

= Fahrzeugmasse

J_Fzg

= Massenträgheit Fahrzeug

l

= Radstand

l_v

= Abstand Schwerpunkt zur Vorderachse des Fahrzeug

l_h

= Abstand Schwerpunkt zur Hinterachse des Fahrzeug

Θ_Str

= Strassenquerneigung

µ_Str

= Strassenreibwert

The following variables are used to describe the system of equations:

t

= time course

[K]

= Time steps of a time-discrete system

δ _L

= Steering wheel angle

δ _V

= Steering angle front

β (t)

= Float angle

α _V (t)

= Slip angle of the tires on the front axle

F _yV (t)

= Lateral force front axle

_AH (t)

= Slip angle of the tires on the rear axle

c _αH

= effective skew stiffness of the tires on the front axle

F _yH (t)

= Lateral force rear axle

c _αH

= effective skew stiffness of the tires on the rear axle

a _ysens

= the lateral acceleration measured by a sensor

a _Yquer

= Lateral acceleration component from the radial force

a _ygravi

= Lateral acceleration component from the gravimetric force

v _x (t)

= Vehicle longitudinal speed

v _y (t)

= Vehicle lateral speed

v _x (t)

= Vehicle reference speed (typically determined from wheel speeds)

Ψ '(t)

= Vehicle yaw rate

Ψ '(t)

= Fahrzeuggier'beschleunigung

m _veh

= Vehicle mass

J _vehicle

= Inertia vehicle

l

= Wheelbase

l _v

= Distance center of gravity to the front axle of the vehicle

l _h

= Distance center of gravity to the rear axle of the vehicle

Θ _Str

= Street bank

μ _Str

= Road friction value

For the vehicle's own movement of the motor vehicle 1 the following kinematic relationship applies v y '(t) = a y (t) - ψ '(t) · v x (t) (1.1)

Furthermore, the following forces and moment balances of the vehicle's own motion can be determined put up.

For an equilibrium of forces of the vehicle's own motion, the following applies: m veh · a y (t) = F SV (t) + F SH (t) (1.2) J veh · Ψ '' (t) = F SH (T) · l H - F SV (T) · l V ) (1.3)

For a kinematic relationship for slip angles of wheels of the motor vehicle 1 applies: α V (t) = δ V (t) - β - l V · (Dψ / dt) / v x (1.4) α H (t) = β + 1 H · (Dψ / dt) / v x (1.5)

For a torque balance in a transverse direction of the motor vehicle 1 can the equations α V (t) = (l H * M * a y (t)) + J · (i.e. 2 ψ / dt 2 )) / (C V (t) · l) (1.6) α H (t) = (l V * M * a y (t) - J · (i.e. 2 ψ / dt 2 )) / (C H (t) · l) (1.7) be set up.

From this, lateral forces acting on the front wheels and on the rear wheels can be determined according to the equations F SV (t) = c V (T) · α V (t) (1.8) F SH (t) = c H (T) · α H (t) (1.9) be determined.

The skew stiffnesses c _V and C _{H of} the front wheels and the rear wheels of the motor vehicle 1 are time-dependent, with an effective coefficient of friction for building up the lateral forces from a rubber compound of the tires in conjunction with a nature of a road surface which is the motor vehicle 1 Composed.

The following relationship applies: C V (t) = c wheel (Α) · coefficient of friction Street (t) (1.6)

It it can be seen that there is a non-linear and time-variant relationship results.

For determining magnitudes of the vehicle's own motion and in particular a deviation of an actual driving course (actual heading) from one by the driver of the motor vehicle 1 given vehicle course (target course) takes place in vehicle dynamics regulations or crash pre-recognition security systems on the previously described equations and the vehicle a track model. It is conceivable to use even more complex models, wherein the following is explained by way of example with reference to the vehicle in-track model.

Furthermore, an approach will be described below first, without the in 1 pointed advantageous relationship between the side force 19 and the tax quantity 17 gets along, with no indirect information about the side force 19 on the wheels of the motor vehicle 1 available. In the approach described below, these are calculated to solve equation systems.

First are prerequisites for an accurate knowledge of a at any time acting adhesion between the road and the tire and a lateral acceleration acting on the motor vehicle.

For a solution to these questions can usually for determining the frictional connection a tire model is assumed, which describes in a suitable form tire properties and for the acting lateral acceleration one at one Ay sensor or a transverse acceleration sensor measured signal can be used as a substitute size.

For this purpose, a discretized equation of state of a kinematic relationship of the driving movement can be used. Advantageously, one type of numerical solution is irrelevant to the following equation. By way of example, the context applies: v y [k + 1] = v y [k] + T A · a y [k] - T A · Ψ [k] / v x [k] (2.1)

The solution of equation 2.1 is basically not possible in the form shown above only in knowledge of the signal of the Ay sensor, since this does not measure a required lateral acceleration of the vehicle, but allows a statement about a sum of the side forces occurring at the vehicle tires. A similar problem persists when not kinematic relationships but forces and moment equilibria are used to establish equations of state as follows: F YVL + F YVR + F YHL + F Yhr = m veh · a ySens (2.2)

In particular, a road inclination, Wankbewegungen the motor vehicle 1 and / or indicated by crosswind forces are also detected by the Ay-sensor.

To solve this problem, the signal of the Ay-sensor must be separated into individual sizes. This can be the context a ySens = a yQuer + a yGravi (2.3) serve. Thus, an equation of state system extended by the road inclination and a road friction can be introduced, wherein it is advantageous for a use of the in 1 described relationship of the control variable 17 and the lateral force 19 a way of modeling road grade and road friction is negligible. By way of example, the following system of equations of state is given: v y [k + 1] = v y [k] - T A ·G earth · Θ str [k] + T A · a yQuer [k] - T A · Ψ '[k] · V x [k] (2.41) β [k + 1] = β [k] -T A ·G earth · Θ str [K] / v x [k] + + T A · a yQuer [K] / v x [k] - T A · Ψ '[k] (2.41a) Θ str [k + 1] = (1 + T A / T K ) · Θ str [k] (2.42) μ str [k + 1] = (1 + T A / T K ) · Μ str [k] (2.43)

In addition to the aforementioned equations of state, two subsequent measurement equations, in particular for small angles, can be specified based on sensor signals. Advantageously, the specified system can be done by means of an observer or by means of a Kalman filter. The observer may have a dynamic pole placement. The equations of state are given as follows: a yQuer [k] = (F SV [k] + F SH [K]) / m veh (2:51) [k] = (F SH [K] · l H - F SV [K] · l V ) / J veh (2:52)

The Equation system of equations 2.41 to 2.52 is advantageous in principle observable.

Together with kinematic relationships of the single-track model, the measurement equations 2.51 and 2.52 can be specified as follows, depending on the state and input variables: a yQuer [k] = - (c V · (Δ V - β - l V · Ψ '/ v x ) + c H · (Β - l H · Ψ '/ v x )) / M veh (2.51a) Ψ '' [k] = (-c H · (-Β + l H · Ψ '/ v x ) · L H + c V · (Δ V - β - l V · Ψ '/ v x ) · L V ) / J veh (2.52b)

In addition, it is possible to know from a knowledge about a curvature of one of the motor vehicle 1 trajectory traced additional information. Advantageously, in a known curve radius R, a slip angle at a rear axle of the motor vehicle 1 be calculated directly. A conversion to the vehicle lateral speed of the motor vehicle 1 can be given in the following algebraic equation: β [k] = (l H / R - m / c H · L / l H · a yQuer [K]) · v y [k] (2.53)

Advantageously, in knowledge or in a calculation of the current curve radius, for example from wheel speeds, by means of the wheel sensors of the motor vehicle 1 can be determined, an additional independent measurement equation can be established. Alternatively and / or additionally, it is possible to obtain information for the dynamic pole placement of the observer from this context.

Advantageously, a solution can be found without the side force 19 must be measured explicitly. However, this is only the case if, as input variables, an exact knowledge of the tire properties, in particular skewing properties and the nature of the road surface, a wheelbase and a mass of the motor vehicle 1 available. Advantageously, the equation system described above by means of the in 1 shown relationship between the taxable amount 17 and the lateral force 19 be significantly improved again.

This can advantageously lead to a particularly good result even under comparatively difficult conditions. The previously described time-variant non-linear equation system, together with the, as in 1 described detectable lateral forces 19 despite the following, in a real driving operation of the motor vehicle 1 conditions are very high:
Usually, a friction value of the road is not known or can only be estimated within certain limits, whereby the system of equations described above can be extended by a state estimation for the road friction coefficient.

Further, the state equations 2:41 to 2:43 and the measurement equations are 2:51 to 2:52 coupled to each other as follows: β = f (α _v, α _h) = f (v _x).

Further is to take into account that properties of the tires of the Changing motor vehicles, for example for a summer and a winter operation.

In addition, the mass of the motor vehicle and the moment of inertia are subject to changes, for example due to a loading of the motor vehicle 1 , where a position of a center of gravity changes. Furthermore, the motorization of the motor vehicle may play a role in this regard.

In addition, if the in 1 Side force shown 19 not as a measure in the glide a yaw acceleration by differentiation from a can be determined by means of a yaw rate sensor yaw acceleration be determined. In principle, signals resulting from it have a noise that can be filtered accordingly before the differentiation, wherein basically undesirable phase relationships with respect to the yaw acceleration occur in such a way that the value is available only with a certain time delay.

The above-mentioned large number of inaccurate parameters or delayed signal information require that the above-mentioned model is subject to a certain blurring. Advantageously, by including the lateral force 19 this blur can be reduced. Advantageously, the resulting phase relationships can be decisively reduced, wherein advantageously an otherwise occurring time delay, which would interfere with changing conditions, also does not occur or only to a significantly lesser extent. Advantageously, by including the lateral force 19 a state variable describing the state of the motor vehicle, for example in the form of a vehicle lateral speed with only a minimal delay, is made available. It is also possible, even in transitional phases, ie in a changing state of the motor vehicle 1 to accurately detect the state quantity and thus also to map derived variables with a maximum accuracy, that is to say the least possible blurring.

Advantageously, the method described above, ie the state and measurement equations, can be extended to include the latter by means of calculating the lateral force 19 have a higher robustness. Advantageously, by measuring the lateral force 19 depending on the taxable amount 17 the equation system described above can be extended by axis-specific equations. Furthermore, it is advantageous that the additionally possible equations have no motor vehicle mass. Moreover, this has the advantage that the described coupling of the state and measurement equations can be broken. This can be done for a front axle steering by means of the equation F SV = c V · (Δ V - β - l V · Ψ '/ v x ) (3.11) respectively. If the motor vehicle also has a rear axle steering can by means of the equation F SH = -C H · (Β - l H · Ψ '/ v x ) (3.12) also acting on the rear wheels side force analogous to in 1 shown lateral force 19 be included.

With knowledge of the front axle side force according to equation 3.11 and the rear axle side force according to equation 3.12, the vehicle mass and the vehicle inertia of the motor vehicle can advantageously also be known 1 with additional information about vehicle lateral acceleration and vehicle yaw acceleration, are determined from the following equations: m veh = (F SV (t) + F SH (T)) / a y (t) (3.12) J veh = (F SH (T) · l H - F SV (T) · l V ) / ψ '' (t) (3.13)

In the following, a model according to the invention is described in which the in 1 Side force shown 19 incoming, this by means of the electric steering 3 as sole front axle steering can be determined. So this comes only with the information on a front axle of the motor vehicle 1 adjacent lateral force 19 out. In knowledge of a transmission behavior of the electric steering 3 , In particular a translation of a corresponding steering gear, the following moment balance can be established: T driver + T engine · i gear - T lateral force - T friction = 0 (4.11)

That of the electric motor of the electric steering 3 supplied torque T _engine can by a non-illustrated control unit of the backup drive 7 the electric steering 3 be determined directly by measuring the currents, in particular via a Parkin transformation equation.

The driver's manual steering torque 13 T _driver can advantageously directly by means of the measuring device 15 , For example, a torque sensor can be determined. Alternatively, it is possible, via a replacement model at known angular velocities above and below a torsion bar of the electric steering 3 the manual steering torque 13 to measure indirectly. A system _friction T _friction is beneficial in relation to the side force 19 during a cornering of the motor vehicle 1 negligible and therefore can either be neglected or from measurements in the electric steering 3 be estimated with sufficient accuracy.

This applies to the side force to be determined 19 at the front axle of the motor vehicle 1 : F SV (t) = T lateral force · i steering = T engine · i gear - T driver - T friction (4.12)

Alternatively, it is conceivable for the electric steering 3 to use another replacement model adapted to specific designs. Basically, the lateral force 19 by means of any model or knowledge of the transfer behavior of the electric steering 3 be provided in any manner in a sufficiently good quality.

According to the invention, the following measurement equation can be set up for the solution of the equations of motion: Ψ '= (δ V - β - F YSV / c V ) * (V x / l V ) (4.2)

For the equations of state, this yields: v y [k + 1] = v y [k] - T A ·G earth · Θ str [k] + T A · a yQuer [k] - T A · Ψ [k] · v x [k] (4.31) β [k + 1] = β [k] -T A ·G earth · Θ str [K] / v x [k] + + T A · a yQuer [K] / v x [k] - T A · Ψ '[k] (4.31a) Θ str [k + 1] = (1 + T A / T K ) · Θ str [k] (4.32) μ str [k + 1] = (1 + T A / T K ) · Μ str [k] (4.33)

For the measurement equations follows: a yQuer [k] = (c V · (Δ V - β - l V · Ψ '/ v x ) + c H · (Β + l H · Ψ '/ v x )) / M veh (4:41) Ψ '[k] = (δ V [k] - β [k] - F YSV [K] / c V ) * (V x [K] / l V ) (4.42)

Advantageous is the measurement equation 4.42 instead of the previously described measurement equation 2.52 provided. Alternatively, it is conceivable in addition also to provide the measurement equation 2.52.

The system of equations 4.31 to 4.42 advantageously has a comparatively lower dependence on vehicle parameters. Advantageously, the yaw rate can be mapped directly as a measurement equation. Advantageously, the yaw rate can be measured very reliably by means of the yaw rate sensor, wherein a significantly higher accuracy can be achieved compared to the measurement equation 2.52, since the step of differentiating the yaw rate can be dispensed with. Advantageously, the vehicle dynamics of the motor vehicle 1 thus clearly better picture.

Advantageously, either the side force 19 on the front wheels of the motor vehicle 1 or corresponding side forces on the front and rear wheels are determined. Furthermore, the vehicle's own movement, in particular the vehicle lateral velocity, the vehicle's floating angle and the lateral acceleration acting on the vehicle may advantageously be determined in conjunction with the road characteristics. Furthermore, it is advantageously provided that, if appropriate, different models can be used for the vehicle model formation, for example a linear single-track model, a non-linear single-track model, a two-track model, a nonlinear two-track model and / or other models. Furthermore, it is advantageously possible to solve the system equations 4.31 to 4.42 in any desired manner, for example by means of an observer, in particular a Kalman filter.

Advantageously, by means of the electric steering 3 or by means of the control variable 17 the lateral force 19 be determined.

Advantageous can not otherwise measurable state variables, such as the slip angle or the road inclination and optionally tire parameters with high accuracy be determined. Advantageously, this can defies changing Parameter of the motor vehicle, such as a load and / or a change of ride properties with a high Accuracy done. Advantageously, by means of the additional measurement equations the observer more sizes available to improve the observer's model accordingly.

In particular, the slip angle and / or the lateral velocity of the motor vehicle 1 can be determined as components of a state vector by means of the observer, wherein the observer can be designed as a Luenberger observer or Kalman filter. The function of an observer or Kalman filter is known, so that a more detailed description is dispensed with. The observer can change the shape X k + 1 = A · X k + B · U exhibit.

für den Zustandsvektor zum Abtastzeitpunkt k,

für den Zustandsvektor zum Abtastzeitpunkt k + 1,

für den Eingangsvektor mit den gemessenen Eingangsgrößen und A, B für Systemmatrizen mit den Parametern des Modells.There are:

for the state vector at the sampling time k,

for the state vector at the sampling time k + 1,

for the input vector with the measured input quantities and A, B for system matrices with the parameters of the model.

für einen berechneten Messvektor steht, der die berechneten Messgrößen als Komponenten enthält.The equations a yQuer [k] = - (c V · (Δ V - β - l V · Ψ '/ v x ) + c H · (Β - l H · Ψ '/ v x )) / M veh (2.51a) Ψ '' [k] = (-c H · (-Β + l H · Ψ '/ v x ) · L H + c V · (Δ V - β - l V · Ψ '/ v x ) · L V ) / J veh (2.52b) represent the measurement equations, where

represents a calculated measurement vector containing the calculated quantities as components.

einen gemessenen Messvektor dar, der die gemessenen Messgrößen als Komponenten enthält.Analogously provides

a measured measurement vector containing the measured quantities as components.

The parameters of the mathematical model (parameters of the equations) are corrected so that the difference ΔY = Y _calculated - Y _{measured measured} minimum.

According to the invention by means of the control variable 17 the electric steering 3 the lateral force 19 at the front axle of the motor vehicle 1 be determined on the basis of the moment balance of equations 4.11, 4.12, with knowledge of the lateral force 19 corresponding equations of motion can be established (equation 4.2), which can be used according to the invention as a measurement equation of the observer.

The equations 4.31 to 4.33 are thus advantageously obtained as equations of state and the equations 4.41 to 4.42 as measurement equations, whereby the vector according to the invention now contains the better measurable yaw rate as a measured variable as follows:

Advantageously, in vehicles with an additional rear axle steering in the same way as the lateral force 19 at the front axle also a corresponding lateral force at the rear axle can be calculated. With known lateral forces on the front and rear axles, it is advantageously possible to calculate the vehicle mass and vehicle inertia according to equations 3.12 and 3.13.

Advantageous can be set by the observer by a pole position whether the minimization of ΔY is rather fast, where the equations of state dominate or rather run slowly, where the measurement equations dominate.

In an advantageous embodiment of the method, the poles of the observer can dynamically depending on the state or a driving state of the motor vehicle 1 be predetermined such that at a tendency to unstable driving condition, for example, a fast cornering, the state equations dominate and dominate the measurement equations in a relatively stable driving condition, such as a straight-ahead driving. Under a stable driving condition can be understood when the motor vehicle 1 a curve with a large radius passes through to the straight ahead. Under a rather unstable driving state can be understood when the motor vehicle passes through a curve with a small radius, in particular connected to a relatively high cornering speed. Advantageously, the radius can be determined by means of wheel speeds measured at the vehicle wheels.

1

motor vehicle

3

electrical steering

5

Human / machine interface

7

electrical support drive

9

Radanlenkung

11

electrical steering torque

13

manual steering torque

15

measuring device

17

control variable

19

lateral force

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10307848 A1 [0002]

Claims (10)

Method for determining at least one motor vehicle ( 1 ) or a state of the motor vehicle ( 1 ) characterizing size, characterized by the steps: - determining a direction of travel of the motor vehicle ( 1 ) influencing control variable ( 17 ), - determining the size as a function of the control variable ( 17 ). Method according to the preceding claim, with the step: - determining the control variable ( 17 ) as one for providing at least one steered wheel of the motor vehicle ( 1 ) by means of an electric steering ( 3 ) required electricity. Method according to the preceding claim, with the step of: determining on the at least one steered wheel of the motor vehicle ( 1 ) acting electric steering torque ( 11 ) depending on the current. Method according to one of the preceding claims, comprising the step of: - determining a driver of the motor vehicle ( 1 ) manually generated manual steering torque ( 13 ) by means of a measuring device ( 15 ). Method according to one of the preceding three claims, with the step: determining a lateral force acting on the at least one wheel ( 19 ) by means of a transmission behavior of the electric steering ( 3 ) and in dependence on the manual steering torque ( 13 ) and the electrical steering torque ( 11 ). Method according to one of the preceding claims, with the step: - determining the size by means of a control variable ( 17 ) or the lateral force calculated from this ( 19 ) having measuring equation. Method according to the preceding claim, with which Step: - Determine the size as a vehicle yaw rate by means of the measurement equation. Method according to one of the preceding claims, comprising the step of: determining front side force and rear side force acting on front wheels and on rear wheels by means of the transmission behavior of the electric steering ( 3 ) and in dependence on the manual steering torque ( 13 ) and the electrical steering torque ( 11 ). Method according to the preceding claim, with the step: determining a vehicle mass and an inertia of the motor vehicle ( 1 ) depending on the lateral forces. Motor vehicle ( 1 ), designed, constructed and / or constructed for carrying out a method according to one of the preceding claims, characterized by a control variable ( 17 ) controllable device for influencing a direction of travel of the motor vehicle ( 1 ), depending on the size of the tax ( 17 ) a the motor vehicle ( 1 ) or a state of the motor vehicle ( 1 ) characteristic size can be determined.