DE102008001993B4 - Method for controlling the driving dynamics behavior of a motor vehicle with at least two different adjusting devices and device for this - Google Patents

Abstract

Method for controlling the driving dynamics behavior of a motor vehicle with wheels, wherein at least two different adjusting devices (4) for making driving dynamics changes are ordered to carry out adjusting interventions in such a way that a maximum value of a friction coefficient present on the wheels that is utilized is minimized, characterized in that a penalty function (P) is used in the allocation of the actuator intervention performance, which determines the intervention intensity of the actuators (4).

Description

The invention relates to a method for controlling the driving dynamics behavior of a motor vehicle with wheels, wherein at least two different adjusting devices for making driving dynamics changes are ordered to carry out adjusting interventions in such a way that a maximum value of a used adhesion coefficient present at the wheels is minimized.

From the prior art, such as the EP 0920389 B1 a method and a device for controlling movement variables representing the movement of the vehicle are known. In motor vehicles, especially in those with internal combustion engines, different vehicle dynamics control devices are used, which have actuating devices, as they are from the EP 0920389 B1 are known. The use of brake intervention control devices, ie control devices that act on the brakes of a motor vehicle, is known from this document. Such systems are also referred to as brake control systems, as used in ESP systems (ESP =
Electronic Stability Program) occur, used.

In addition to such intervention setting devices, however, vehicles of more recent design are also equipped with further active setting systems that influence the driving dynamics. So-called steering angle adjusting devices are known, which work according to the principle of angle superimposition (“Active Front Steering”), but also partial dynamic adjusters for adjusting wheel contact forces, for roll stabilization (“Active Roll Control”) and traction adjusters for transferring drive torque between the wheels of an axle Motor vehicle ("torque vectoring") known.

With these systems, controller-specific functions are usually implemented, such as driving speed-dependent changes in a steering ratio with Active Front Steering or leveling with Active Roll Control.

• Max {µa_RadVL,µa_RadVR,µa_RadHL,µa_RadHR}, derart, dass der hier gefundene maximale ausgenutzte Kraftschlussbeiwert µa an einem jeweiligen Rad (z.B. vorne links, d.h. VL) herangezogen wird. Dieser sog. ausgenutzte Kraftschlussbeiwert ist definiert als Quotient aus der resultierenden Radkraft in Längs- und Querrichtung, dividiert durch die Radnormalkraft. Die Zuteilung der Stelleingriffsdurchführung wird dabei so angeordnet, dass der maximale ausgenutzte Kraftschlussbeiwert minimiert wird, wobei ein Gütemaß über die Verteilung der Eingriffe auf die zur Verfügung stehenden Stellvorrichtungen minimiert wird.

From the specialist literature, for example from the publication "Integrated vehicle dynamics control with individual wheel actuators" from Shaker Verlag Aachen, published in 2007 by the author R. Orend, a generic approach to the distribution of horizontal and vertical dynamic control interventions on existing control devices is known. There it is proposed to determine the adjustment interventions with the help of a mathematical optimization process in such a way that the use of adhesion is minimal:

• Max {µa_RadVL, µa_RadVR, µa_RadHL, µa_RadHR}, such that the maximum utilized adhesion coefficient µa found here on a respective wheel (eg front left, ie VL) is used. This so-called utilized adhesion coefficient is defined as the quotient of the resulting longitudinal and lateral wheel force divided by the normal wheel force. The assignment of the implementation of the adjustment intervention is arranged in such a way that the maximum friction coefficient utilized is minimized, with a quality measure of the distribution of the interventions among the available adjustment devices being minimized.

However, the solution approach known from the technical literature has the disadvantage that the influence on comfort caused by the activation of the corresponding adjusting devices is not taken into account. Corresponding adjustment interventions can take place on a very uncomfortable adjustment device, although the use of a more comfortable adjustment device would mean only a slightly higher use of the coefficient of friction, ie would lead to a slightly higher utilized coefficient of adhesion.

In this application, the term "wheels" includes all devices that cause an element to roll for the purpose of moving on a surface, including tires, rollers and chain drives.

This problem is exacerbated by the fact that modern driving dynamics control systems are characterized by the close networking of the ESP with many other driving dynamics actuators, such as front-axle and rear-axle steering, torque vectoring, roll stabilization and the like. The resulting high combinatorial variety of driving dynamic intervention options, which is reinforced by the fact that many adjusting devices are often available as optional equipment variants, further increases the problem.

Further prior art is from DE 102 26 683 A1 known. the DE 102 26 683 A1 describes a method or a device for influencing the driving behavior of a vehicle. The influencing aims to increase driving stability and thus driving comfort for the driver of the vehicle raise. This goal is achieved by controlling at least two systems in the vehicle, which improve driving behavior and thus driving stability. The essence of the invention consists in the fact that a system is activated in a predetermined sequence depending on the activation and/or on the effect achieved by the activation on the driving behavior of the above systems. In this case, the sequence provided for is first the activation of a chassis system, followed by a steering system and then a braking system.

Disclosure of Invention

It is the object of the present invention to avoid the disadvantages of the prior art and to provide the general public with an efficient method for controlling the driving dynamics behavior of a motor vehicle.

According to the invention, this object is achieved with a method according to claim 1, which uses a penalty function P in the allocation of the implementation of the control intervention, which determines the intensity of use of the control devices.

Advantages of the Invention

Such a method ensures a practice-oriented distribution of the interventions in the vehicle movement to the existing control devices. The individual adjusting devices are controlled according to their prioritization, so that higher-priority adjusting devices act on the driving-dynamic behavior more or in time before the other adjusting devices.

The distribution or arrangement of the control interventions is now based exclusively on a driving dynamics optimum.

In the following, advantageous embodiments are described in more detail, which are also claimed in the dependent claims.

For example, it is particularly advantageous if the penalty function P takes into account those actuators that cause a great loss of comfort for a vehicle occupant of the motor vehicle such that these actuators are assigned a lower intervention intensity than those actuators that cause less loss of comfort. As a result, the comfort properties of the individual actuating devices are taken into account, which leads to greater comfort when controlling the driving dynamics behavior. The use of such methods in motor vehicles increases the chances of selling such a motor vehicle.

If the penalty function P, the adjusting device, which causes a great loss of comfort, is taken into account with a high factor, the effects of the individual adjusting devices are specifically addressed, which leads to more precise control.

In order to prevent the motor vehicle from "juddering" during regulation, it is advantageous if a brake intervention adjustment device is taken into account with a high factor. Brake intervention adjustment devices in particular have a major impact on the comfort felt by vehicle occupants of a motor vehicle.

In order to enable simple regulation, it is advantageous if the penalty function takes into account the change in the brake pressure over time of at least one wheel.

Since the effects that an active steering device has on the comfort level of vehicle occupants are less, it is advantageous if a steering angle adjusting device contained in such an active steering device is taken into account with a low factor.

A simpler implementation results when the penalty function takes into account the change in the steering angle over time in order to minimize an actuating gradient that occurs in the process.

If, during or before the allocation of the control intervention implementation, a check of the underlying models, such as a reference model, is analyzed in order to condition a parallel setting of the individual control devices if a limit value is exceeded, the validity of the models used is checked and, if the result is negative, on a tried-and-tested control strategy. It is thus constantly checked whether a comfort-oriented allocation of the control interventions is appropriate, ie whether the utilization of the traction is in a range in which the models, in particular the tire models used, are still sufficiently accurate.

An estimate of the actual coefficient of friction has proven to be a particularly efficient limit value for a limit coefficient, which is required for the above consideration.

The invention also relates to a driving dynamics control device for controlling the driving dynamics behavior of a motor vehicle with wheels with at least two different adjusting devices for making driving dynamics changes, whereby the implementation of adjusting interventions is arranged in such a way that a maximum value of a friction coefficient present on the wheels that is utilized is minimized, and wherein a Penalty function is used in the allocation of the adjustment intervention implementation, which determines the intervention intensity of the actuator. Such devices can be used in existing motor vehicles and lead there to a correspondingly improved driving dynamics regulation, in particular to a more comfort-oriented and thus more pleasant regulation of the driving dynamics behavior.

character list

• 1 den Ablauf einer erfindungsgemäßen Stelleingriffsverteilung.

The invention is described in more detail below with reference to the drawings. It shows:

• 1 the course of a control intervention distribution according to the invention.

Embodiments of the invention

In 1 the sequence of a method according to the invention is shown schematically. In 1 Reference number 1 designates a driving dynamics control device, which directs a driving dynamics target value to a switching device 2 . If this switching device 2, which is a switch in the present exemplary embodiment, is switched on, the setpoint runs into a testing device 3. In the switching device 2, the driving dynamics control interventions are distributed to existing control devices 4.

In the switching device 2, the distribution is realized while minimizing a maximum utilized coefficient of adhesion with the addition of a penalty function. The penalty function depends on the vehicle and not on the referees. This happens according to: $$\text{Max}\left\{\mathrm{\mu }\text{a\_RadVL}\text{,}\mathrm{\mu }\text{a\_RadHL}\text{,}\mathrm{\mu }\text{a\_RadHR}\right\}+\text{P}\text{.}$$

$$\text{P\_Lenkwinkelleingriff}=\text{max}\left(\text{Dft\_Udt}\right).$$

P is the penalty function. The penalty function P evaluates the comfort effects of the control interventions. P is used in each case as a function of the intervention intensity of the individual adjusting devices 4 . The variables that contribute most to the impairment of comfort are evaluated, e.g.: $$\text{P\_brake intervention}=ƒP\_Ra\mathrm{i.e}VL,P\_Ra\mathrm{i.e}VR,P\_Ra\mathrm{i.e}HL,P\_Ra\mathrm{i.e}HR)\mathrm{i.e}t;$$

$$\text{P\_steering angle intervention}=\text{Max}\left(\text{Dft\_Udt}\right).$$

When the brakes are applied, the overall intensity affects driving comfort, e.g. due to the reducing loss of speed. A steering angle intervention with a high adjustment gradient also reduces the steering comfort due to the repercussions that arise on the driver of the motor vehicle.

By taking into account the penalty function P in an optimization criterion, the use of convenient adjusting devices is favored and the use of less comfortable adjusting devices is penalized. This results in a comfort- and friction-oriented distribution of the adjustment interventions.

In addition, the validity of the underlying models is continuously analyzed in order to switch to classic driving dynamics control such as ESP or ESP in combination with Dynamic Steering Angle Control (DSA), which includes Active Front Steering (AFS) in the event of high model errors.

In doing so, e.g. B. defines a suitable limit for the adhesion use. This is an estimate of the actual coefficient of friction. If a maximum of the adhesion coefficients is above this limit values, then the model is recognized as invalid and the optimization is terminated according to the above formula.

This check takes place in the test device 3, which forwards a corresponding command to the evaluation device 5. The evaluation device 5 thus evaluates the validity of the underlying models. On valid models, the switching device is left on and an alternative switching device 6, activatable instead of switching device 2, is left off.

In the case of invalid models, the switching device 2 is switched off and signal forwarding to the testing device 3 is accordingly initiated. The alternative switching device 6 is now switched on, so that classic control interventions by the driving dynamics control device 1 are passed on to the individual control devices 4 . Parallel rules now take place in a collaborative structure.

An optimal compromise between sportiness, comfort and safety is thus achieved in the driving dynamics control. The approach is scalable and automatically adapts to the existing driving dynamics actuators. The situations of the failure of an actuator or the case that an actuator is optionally available as an equipment variant are covered with minimal additional effort. In this way, the complexity of the development process of driving dynamics controls for the networking of many driving dynamics actuators remains manageable despite the "combinatorial explosion". The comfort of the interventions increases and the energy requirement of the actuating devices decreases.

Claims (10)

Method for controlling the driving dynamics behavior of a motor vehicle with wheels, wherein at least two different adjusting devices (4) for making changes in driving dynamics are ordered to carry out adjusting interventions in such a way that a maximum value of a friction coefficient present on the wheels that is utilized is minimized, characterized in that a penalty function (P) is used in the allocation of the actuator intervention performance, which determines the intervention intensity of the actuators (4). procedure after claim 1 , wherein in the penalty function (P) those adjusting devices (4) that cause a great loss of comfort for a vehicle occupant of the motor vehicle are taken into account in such a way that these adjusting devices (4) are assigned a lower intervention intensity than such adjusting devices (4) which have less cause loss of comfort. procedure after claim 2 , wherein the penalty function (P) takes into account that adjusting device (4) that causes a great loss of comfort with a high factor. procedure after claim 3 , where a brake intervention adjustment device is taken into account with a high factor. procedure after claim 4 , wherein the penalty function (P) takes into account the change in the brake pressure over time on at least one wheel. Procedure according to one of claims 3 until 5 , where a steering angle adjusting device is taken into account with a low factor. procedure after claim 6 , where the penalty function (P) takes into account the change in the steering angle over time in order to minimize an adjustment gradient that occurs in the process. Procedure according to one of Claims 1 until 7 , wherein during or before the allocation of the control intervention implementation, a check of the underlying models, such as a tire model, is analyzed in order to condition a parallel setting of the individual control devices (4) if a limit value is exceeded. procedure after claim 8 , where the limit value is an estimate of the existing coefficient of friction. Driving dynamics control device (1) for controlling the driving dynamics behavior of a motor vehicle with wheels, having: at least two different adjusting devices (4) for making changes in driving dynamics, whereby the execution of adjustment interventions is arranged in such a way that a maximum value of a used adhesion coefficient present at the wheels is minimized, characterized in that a penalty function (P) is used when allocating the execution of adjustment interventions, which determines the intervention intensity of the adjustment device (4).

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