DE102009026994A1 - Device for regulating transverse dynamic of vehicle, has scanner which determines actual-slip angle of vehicle, where unit is provided for presetting target-slip angle - Google Patents

Abstract

einen Regler (32) sowie einen Aktuator (33) zum Einstellen des Schwimmwinkels (β_H), basierend auf einer Regeldifferenz (e), aufweist.The invention relates to a device for controlling the lateral dynamics of a vehicle (20), which comprises an observer (31), which determines an actual slip angle (β _H ) of the vehicle (20). According to the invention, a float angle control is performed, wherein the device (30, 40) further comprises a unit (10, 41) for specifying a target slip angle

a regulator (32) and an actuator (33) for adjusting the slip angle (β _H ) based on a control difference (e).

Description

State of the art

The invention relates to a device for controlling the lateral dynamics of a vehicle according to the preamble of claim 1.

From the prior art, various driving dynamics controller, such. As ESP, known to regulate the lateral dynamics of a vehicle. Essentially, they serve to assist the driver in critical driving situations in which the vehicle over- or understeer, for example. These systems usually control the yaw rate of the vehicle, wherein the current actual yaw rate detected by a yaw rate sensor, and the target yaw rate using a mathematical model, such. B. the so-called single-track model is calculated. If the deviation between setpoint and actual values is too high, the system intervenes in the driving mode. The interventions usually take place via the wheel brakes or active steering.

Although the movement of the vehicle about the vertical axis can be regulated with the aid of the previously described yaw rate control, it is not possible to adjust the orientation of the vehicle, ie. H. the float angle to influence in the desired manner. Thus, driving situations can occur in which the vehicle drifts transversely to the longitudinal direction through a curve.

Disclosure of the invention

In this respect, it is an object of the invention to provide a device for controlling the lateral dynamics of a vehicle, with the float angle of the vehicle can be adjusted.

The object is achieved according to the invention by the features of independent claim 1. Further embodiments of the invention are the subject of dependent claims.

According to the invention, it is proposed to provide a Schwimmwinkelregler comprising an observer, which determines the current actual slip angle of the vehicle. An observer within the meaning of the invention is any device which determines the float angle from different measured and / or estimated variables. The desired float angle we provided according to the invention of a setpoint generator. This can the setpoint z. B. model based calculate or a fixed value, such. B. the value zero or near zero, pretend. If the control deviation is too large, the float angle controller uses an actuator, such. B. an active differential, in the driving operation to generate a moment about the vertical axis of the vehicle, which corrects the slip angle.

The float angle controller according to the invention preferably uses a differential, such. B. an active or passive differential (with brake) and / or a steering actuator as an actuator of the scheme. The service brake, such. As a hydraulic brake, is preferably not used by the float angle controller. The first-mentioned actuators have the advantage over the service brake that they react much faster than the wheel brakes of a hydraulic brake system.

The desired slip angle is calculated according to a first embodiment by means of a mathematical model. A preferred mathematical model is the single-track model according to Richert / Schunk, as shown in the following description of the figures. The target float angle is preferably calculated based on the rear axle of the vehicle. This method is less computationally intensive and therefore faster compared to calculating the target slip angle relative to the center of the vehicle.

According to a second embodiment of the invention, the value of the target slip angle to a fixed value, such. As the value zero or near zero set. This further reduces the complexity of the control. Incidentally, a constant target slip angle also causes the wheel slip angles at the front axle to be reduced. In addition, by setting the target slip angle to zero, starting on a roadway with μ-split conditions (different coefficients of friction on the left and right tires) can be simplified since the tendency for the tail to break out can be corrected immediately via the slip angle.

The calculation of the actual and / or target slip angle can be carried out at a repetition rate that depends on the speed of the vehicle. In principle, it is the case that the faster the vehicle travels, the higher the repetition rate is.

The floating angle controller according to the invention preferably generates a yawing moment value, which is converted by means of an actuator, as the output or manipulated variable. The manipulated variable can also be implemented by several actuators at the same time.

The Schwimmwinkelregler invention can, for. B. as a linear controller (state controller, etc.), compensation controller (linear or non-linear) or be designed as a so-called robust controller.

Brief description of the drawings

The invention will now be described by way of example with reference to the accompanying drawings. Show it:

1 a block diagram for the general description of a system as a mathematical model;

2 a representation of a vehicle, in which the parameters of a mathematical vehicle model are shown;

3 a block diagram of a floating angle controller according to a first embodiment; and

4 a block diagram of a floating angle controller according to a second embodiment.

Embodiments of the invention

The 1 and 2 show a general block diagram of a mathematical model 10 for a time-variant system.

A physical system, such. B. a vehicle 20 , physical state quantities, which can be summarized as an input vector u → (t), converts into other physical quantities that can be represented as an output vector y → (t). For example, when the driver operates the steering wheel, the steering angle δ _{F forms} the state quantity of the input vector u → (t). The vehicle 20 then moves into the curve with a slip angle β and turns at a yaw rate ψ. around the z-axis. Slip angle β and yaw rate ψ. form in this case, the physical state variables of the output vector y → (t).

The states of the vehicle 20 change with time. This property is determined by a time-derived state vector x → (t), an integrator 12 and a state vector x → (t). In this case, the state vector x → (t) is formed from the sum of the state vector x → (t) last updated by the system matrix A and the input vector u → (t) modified by the input matrix B. The updated state vector x → (t) is then changed by the output matrix C and finally output as sum with the input vector u → (t) changed by the pass-through matrix D as the output vector y → (t). Mathematically, the model can be 10 describe as follows: x → (t) = A · x → (t) + B · u → (t) (1) y → (t) = C · x → (t) + D · u → (t) (2)

To model the lateral dynamics of the vehicle 20 out 2 see the equations (1) and (2) z. B. as follows:

The state variables of the state vector x → (t) are here the slip angle β and the yaw rate ψ. These time-variable modeling variables are constantly updated during the drive.

The modeling variables of the system matrix A are the skew stiffnesses C _V , C _{H of} the front and rear wheels, the distances I _V , I _{H of} the front and rear axles from the center of gravity of the vehicle 24 , the vehicle mass m and the moment of inertia J _{Z of} the vehicle 20 around the z-axis, as well as the vehicle speed v.

The input matrix B contains the vehicle mass m, the moment of inertia J _Z about the z-axis, the front wheel slip stiffness C _V, the front axle distance I _V to the vehicle center of gravity, and the vehicle speed v as modeling quantities.

If the driver specifies a specific steering angle δ _F , then the model will be used 20 a slip angle β and a yaw rate ψ. calculated (output vector y → (t)). The actual yaw rate ψ. and the actual slip angle β of the vehicle are measured or model-based estimated.

According to a specific embodiment of the invention, the slip angle β with respect to the rear axle of the vehicle 20 calculated. For this purpose, the additionally provided yawing moment M _{Z of} the actuator system is introduced as a further input variable into the input vector u → (t). The state vector x → (t) in this case is the slip angle β _H at the rear axle of the vehicle 20 and the yaw rate formed. The corresponding model equations are:

By this, related to the rear axle of the vehicle model understeer or oversteer of the vehicle can be detected and corrected faster.

3 shows the control loop 30 of a driving dynamics controller according to a first embodiment of the invention, although only the control circuit for the slip angle is shown. This includes a mathematical model 10 , which are the setpoints for the slip angle β _H and the yaw rate z. B. calculated according to one of the model equations described above, as well as an observer 31 which model-based or directly determined the actual slip angle β _H from various measurement and estimated variables. The determination of the slip angle is well known from the prior art.

The model 10 obtained from the observer 31 the vehicle speed v and the steering angle δ _F. These measurements are required for continuous updating of model equations (5) and (6). At the node 34 Finally, the control difference e is formed. The actual controller 32 , such as As a linear controller determines depending on a compensation yaw moment M _Z , which should be applied to correct the orientation of the vehicle. The yaw moment M _Z is finally from an actuator 33 , such as B. a differential and / or a steering actuator implemented.

In the second embodiment of the control loop 40 from 4 becomes the target float angle β _H not estimated, but permanently set to the value zero (or near zero) (block 41 ). The mathematical model 10 falls completely off, so that the scheme is faster. It can also be seen that the skew angles at the front axle are reduced by a constant adjustment of the slip angle β _H to the value zero. This thus improves the driving behavior of the vehicle.

Claims (8)

Contraption ( 30 . 40 ) for controlling the lateral dynamics of a vehicle ( 20 ), comprising an observer ( 31 ), which has an actual slip angle (β _H ) of the vehicle ( 20 ), characterized in that the device ( 30 . 40 ) a unit ( 10 . 41 ) for specifying a target slip angle ( β _H ), a regulator ( 32 ), as well as an actuator ( 33 ) for adjusting the slip angle (β _H ) based on a control difference (e) of the slip angle (β _H ). Device according to claim 1, characterized in that the observer ( 31 ) one on the rear axle of the vehicle ( 20 ) relative actual slip angle (β _H ) outputs. Device according to claim 1 or 2, characterized in that the unit ( 10 . 41 ) for specifying the target slip angle ( β _H ) a mathematical model ( 10 ). Device according to claim 3, characterized in that the unit ( 10 . 41 ) the target slip angle ( β _H ) is calculated depending on a steering angle (δ _F ) and the speed (v) of the vehicle. Device according to claim 1 or 2, characterized in that the unit ( 10 . 41 ) a target slip angle ( β _H ) with a value of zero or near zero. Device according to one of the preceding claims, characterized in that the actuator ( 33 ) comprises a controllable differential and / or a steering actuator. Device according to claim 6, characterized in that the regulator ( 32 ) is a compensation controller or linear regulator. Device according to one of the preceding claims, characterized in that means for both the control of the slip angle (β _H ) and the yaw rate (ψ.) Are provided.

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