DE10360404A1 - Vehicle`s rolling motion damping method, involves influencing steering angle of front wheels at front axis of vehicle based on rolling speed and/or rolling acceleration of vehicle - Google Patents

Abstract

The method involves influencing a steering angle of front wheels at a front axle of a vehicle based on a rolling speed and/or rolling acceleration of the vehicle and independent of any action of a driver. The rolling speed and/or rolling acceleration of the vehicle are measured using a sensor. Roll bearing of the vehicle is controlled, over single wheel brake grip, based on the influence of the steering angle of the wheels. An independent claim is also included for a method of controlling the transverse motion of a vehicle.

Description

The The invention relates to a method for damping rolling movements of a Vehicle about its longitudinal axis.

It is known by active steering interventions a yaw rate control to realize the driving dynamic condition of the vehicle too stabilize.

outgoing This should also be a damping the rolling motion can be achieved.

mit
A: Term zur Bestimmung des Lenkwinkels in Abhängigkeit von der Giergeschwindigkeit,
K₁, K₂: Vorgebbare FaktorenThis object is achieved by the method according to claim 1. The steering angle (δ) on the steerable wheels, in particular the front wheels of the vehicle, is independently influenced by the driver as a function of a roll size describing the rolling motion of the vehicle about its longitudinal axis. The roll rate and / or roll acceleration may be considered as roll size, whereby the following relationship may be used in particular:

With
A: term for determining the steering angle as a function of the yaw rate,
K ₁ , K ₂ : Predeterminable factors

mit
l_v: Abstand des Fahrzeugschwerpunktes von der Vorderachse
α_v: Schräglaufwinkel an der Vorderachse
β: Schwimmwinkel des Fahrzeugs
v_x: Fahrzeug-LängsgeschwindigkeitThe term A results, for example, too

With
l _v : distance of the center of gravity of the vehicle from the front axle
α _v : slip angle at the front axle
β: float angle of the vehicle
v _x : vehicle longitudinal speed

By the consideration the roll speed and / or the roll acceleration in the Control of the yaw rate can be the roll damping and / or the roll frequency be improved. The roll speed and roll acceleration can measured or estimated (eg Kalman filters).

mit
D: Dämpfung
K:
h_Sp: Höhe des Schwerpunkts
m: Fahrzeugmasse
I_xx: Trägheitsmoment um die Fahrzeuglängsachse xThe model for the roll dynamics is the following equation:

With
D: damping
K:
h _Sp : height of the center of gravity
m: vehicle mass
I _xx : Moment of inertia around the vehicle's longitudinal axis x

und für das DämpfungsmaßIt applies to the natural frequency

and for the attenuation measure

wobei zur Vereinfachung ohne Einlaufverhalten der Seitenkräfte und im linearen Bereich gilt:In equation (2) ma _y can be replaced by the sum of the side force (S _v ) on the front wheels and the side force (S _H ) on the rear wheels:

wherein for simplification without running-in behavior of the lateral forces and in the linear range:

The Side force on the front wheels is proportional to the steering angle at the front axle.

Out (6) and (5) you:

With δ _V = δ _{V, controller} - K ₁ Φ. is given by equation (7)

From equation (8) it can be seen that with the factor K ₁ the damping can be varied or increased.

Because of the running-in behavior of the lateral forces s _V and s _H , the rolling acceleration is also dampened and not only the rolling speed:

K ₁ and K ₂ are freely selectable. By adjusting these two factors K ₁ and K ₂ , the ride comfort can be influenced. The setting can be determined, for example, empirically depending on the type of vehicle.

Around on a sensor for measuring the roll angle, the roll speed or to be able to dispense with the roll acceleration, can be determined by the following Method the roll speed and the roll angle are estimated.

einem ersten Eingang eines Knotens zugeführt wird. Der Ausgangswert des Knotens wird durch zwei in Reihe geschaltete Integratoren zwei mal integriert, wobei man durch die erste Integration den Schätzwert

für die Wankgeschwindigkeit und nach der zweiten Integration den Schätzwert Φ ^ für den Wankwinkel erhält. Die geschätzte Wankgeschwindigkeit wird mit einem Faktor

multipliziert und mit negativem Vorzeichen einem zweiten Eingang des Knotens zugeführt. Der geschätzte Wankwinkel wird mit einem Faktor

multipliziert und mit negativem Vorzeichen einem dritten Eingang des Knotens zugeführt.According to the FIGURE, the equation (2) is simulated in a control unit of the vehicle, wherein the measured lateral acceleration a _{y of} the vehicle's center of gravity is used as an input variable and after a multiplication by a vehicle dependent factor

a first input of a node is supplied. The output value of the node is integrated twice by two integrators connected in series, whereby the first integration yields the estimated value

for the roll speed and after the second integration receives the estimated value Φ ^ for the roll angle. The estimated roll speed is a factor

multiplied and supplied with a negative sign to a second input of the node. The estimated roll angle is one factor

multiplied and supplied with a negative sign to a third input of the node.

Additionally or as an alternative to influencing the steering angle, the roll behavior the vehicle also over Einzelradbremseingriffe be influenced. If both braking as well as steering interventions performed, that's the strength and duration of the steering intervention on the strength and duration of the braking intervention to vote or vice versa.

When independent Thought is in a four-wheel steering the possibility in the scheme the transverse dynamics of a vehicle, the slip angle and the yaw rate to decouple from each other:

1st possibility

If you control the rear axle float angle and the front axle float angle, The vehicle slip angle can be measured or estimated. When the lateral acceleration and the yaw acceleration are measured can, the rule equation for the rear axle float angle and the front axle float angle independent of Vehicle float angle be set up.

2nd possibility

If one simplifies equation (9) by neglecting the running-in behavior of the lateral forces and assuming a constant longitudinal velocity v _x, then according to the time derivative of equation (9):

a_y, v_x) messbar. Anstatt β_H,soll und β_V,soll können β ._H,soll und β ._V,soll geregelt werden.

jeweils mit K₁, K₂: Frei wählbarer VerstärkungsfaktorThus all sizes (ψ.,

a _y , v _x ) measurable. Instead of β _{H, soll} and β _V, β. _{H, shall} and β. _{V, should be} regulated.

each with K ₁ , K ₂ : Freely selectable gain factor

3rd possibility

Instead of to decouple the yaw rate and the vehicle slip angle in the transverse dynamics control, the yaw rate and the float angle velocity decoupled. This allows one to measure the slip angle without.

forwards one obtains equation (15):

These Equation (16) determines the buoyancy control at the rear axle of the vehicle. The setpoint value is the desired float velocity for the Rear axle calculated:

The Controlled variable results to

In addition, can yaw rate control on the front axle of the vehicle respectively. In this way, the yaw rate control is decoupled (Front axle) of the float angle control (rear axle). The advantage is that the float angle velocity in contrast to the float angle is measurable.

4th possibility

Instead of a regulation is at this possibility a controller provided. Thereby are exact knowledge of vehicle parameters, such as B. tire characteristics of advantage. Do you give the target yaw rate, the target vehicle slip angle and their respective time derivatives before, the target steering angle be determined on the front and rear axles.

m·ay = Sv + SH (20) The following applies:

m · a y = S v + S H (20)

The target values for the lateral forces or the steering angles at the front and rear axles are determined on this. In equations (19) to (21), the yaw rate, the yaw acceleration, the slip angle, the lateral force on the front axle, and the side force on the rear axle are replaced by the respective target values. With α ν _{x y} = (. Ψ _target - β _target.) Yields:

The following applies to the slip angles at the front and rear axles: α V, set = SV -1 (p V, set ) (24) α H, set = SH -1 (p H, set ) (25) SH -1 and SH -1 is the inverted stationary side force at the rear or front axle.

from that the target steering angles at the front and rear axle result to:

Claims (6)

Method for damping vehicle roll movements about its longitudinal axis, characterized in that the driver is influenced independently of the steering angle on the steerable wheels of the front axle of the vehicle as a function of a roll size describing the roll motion of the vehicle about its longitudinal axis. A method according to claim 1, characterized in that as a roll size, the roll speed (Φ.) And / or the roll acceleration (

) be used. Method for controlling or regulating the lateral dynamics a vehicle, characterized in that the control of a the transverse dynamics of the vehicle descriptive transverse dynamics size independent of Floating angle of the vehicle takes place. Method according to claim 3, characterized that as yaw rate the yaw rate and / or the float angle velocity is used. Method for controlling or regulating the lateral dynamics a vehicle, characterized in that on one axis the vehicle's regulation of a first the lateral dynamics of the vehicle descriptive transverse dynamics quantity and at the other axle of the vehicle regulating a second the lateral dynamics the vehicle descriptive transverse dynamics variable is carried out. Method according to one of claims 3 to 5, characterized that the control or regulation of the lateral dynamics by targeted Braking of individual wheels and / or independent by driver Steering interventions take place.