DE102009026572A1 - Motor vehicle movement controlling arrangement, has distribution unit determining respective contribution of electronic stability program actuators and active front steering actuator to production of vehicle yaw moment - Google Patents

Abstract

The arrangement has a vehicle greed regulation unit (20) determining vehicle yaw moment to realize desired vehicle movement on the basis of characteristic of input signals (5) for driver inputs. A distribution unit (30) determines respective contribution of electronic stability program (ESP) actuators and active front steering (AFS) actuator to the production of vehicle yaw moment depending on actual driving condition. A tire gradient signal characteristic determination unit (40) determines relative change of contact area forces of tires of a motor vehicle. An independent claim is also included for a method for controlling movement of a motor vehicle.

Description

The The invention relates to an arrangement and a method for vehicle movement control.

In Over the past decade, the development has been more electrohydraulic Brake systems from customers in the automotive sector received very positively since such systems significantly increase driving safety. This also as electronic stability program (= ESP) known braking systems are used to control the yaw behavior of a Vehicle and thus contribute to improving the directional stability of the Vehicle at.

Of Furthermore, not so long ago electromechanical steering actuators introduced in the market. These systems for active front axle steering (also known as AFS systems) are used to control the dynamics of the vehicle by actively controlling the steering angle of the front wheels to control.

With Increasing popularity of AFS and ESP systems is increasing the likelihood of these systems being common in vehicles be used. Since the longitudinal and in the transverse direction acting tire forces highly non-linear and with each other For reasons of safety and for reasons of safety and security Optimization of driving behavior essential that this is a certain Degree of integration is achieved. By integration is meant here that the steering and braking systems are not considered independent systems but that interaction or coupling between the systems. The required regulatory procedures regarding the yawing motion of the vehicle must then be directed to the steering and brake actuators are distributed. Between the two extreme situations an exclusive use of the steering actuator and an exclusive use of the brake actuators there are countless other possibilities for the distribution of the required regulatory intervention.

In conventional solutions for integrating an AFS system and an ESP system, priority is given to ESP interventions, where AFS systems are essentially associated with more comfort-related Systems, such. B. for a variable steering ratio or for parking assistance.

From the EP 1 447 262 A1 For example, a vehicle motion control method is known in which a desired vehicle motion is described by three vehicle forces and three vehicle torques, each being linearly independent of each other. Taking into account the requested vehicle movement and the current vehicle situation, the required vehicle forces and / or vehicle torques are determined which are necessary in order to put the vehicle into the desired movement. Subsequently, a set of actuator manipulated variables is calculated by means of which the difference between the requested vehicle forces and / or moments and the vehicle forces and / or torques that can be generated by means of the actuators is minimized.

Furthermore, from the DE 10 2005 015 241 A1 a method for controlling a vehicle and a control device is known, wherein the requested vehicle forces and / or moments are derived from a requested vehicle movement and wherein the requested vehicle forces and / or moments are dynamically weighted, in order to generate the vehicle forces and / or vehicle torques derive.

It is an object of the present invention, an arrangement and to provide a vehicle motion control method in a vehicle, which is an efficient distribution of the required regulatory processes in terms of optimum driving behavior and taking into account the actuator requirements and the requirements regarding the Allow driving comfort.

These The object is achieved by the arrangement according to the features of the independent claim 1 and the method according to the Characteristics of independent claim 7 solved.

• – eine Fahrzeug-Gierregelungseinheit, welche auf Basis von für Fahrereingaben und/oder Fahrzustandsparameter charakteristischen Eingangssignalen ein zur Erzielung einer gewünschten Fahrzeugbewegung erforderliches Fahrzeuggiermoment ermittelt; und
• – eine Verteilungseinheit, welche in Abhängigkeit vom aktuellen Fahrzustand den jeweiligen Beitrag sowohl der ESP-Aktuatoren als auch des wenigstens einen AFS-Aktuators zur Erzeugung des Fahrzeuggiermomentes bestimmt.

An arrangement for vehicle motion control in a vehicle, the vehicle comprising an ESP system with ESP actuators for selectively braking individual wheels of the vehicle and an AFS system having at least one AFS actuator for controlling the steering angle of wheels of the vehicle, comprising:

• A vehicle yaw control unit which determines a vehicle yaw moment required to achieve a desired vehicle movement on the basis of input signals characteristic of driver inputs and / or driving state parameters; and
• - A distribution unit, which depending on the current driving condition, the respective contribution both the ESP actuators and the at least one AFS actuator for generating the Fahrzeuggiermomentes determined.

By The invention will be a far-reaching integration of an AFS system and an ESP system. The distribution of regulatory operations on the AFS actuators and the ESP actuators is dependent from the actual vehicle state. This means that for a given, actual Vehicle state the most efficient way to use the steering and Brake actuators is calculated. When calculating the most efficient Operation of the steering and brake actuators may be different Criteria are taken into account. First and foremost are the Requirements and boundary conditions of the actuators. Furthermore, additional requirements, z. B. in terms of ride comfort and handling or handling properties be taken into account. By the invention Approach ultimately a total control system is realized, which benefits from the benefits of an active suspension system and above In addition, the driving behavior due to the exploitation of synergy between the two systems "AFS system" and "ESP system" improved.

According to one preferred embodiment occur in the in the inventive Arrangement realized integration of an AFS system and an ESP system in a handling area or mode of the vehicle only steering interventions on, so no reduction in ride comfort and / or vehicle speed he follows. Be in a stability range or mode however, both steering interventions and braking interventions for stabilization used of the vehicle. The inventive Approach leads compared to conventional systems to an improvement of the driving behavior, whereby driving pleasure and driving comfort in the Handling range while improving driving stability be increased in the stability range.

Of Furthermore, the inventive method can in easy way to use different actuators such as B. Electronic differentials ("E-Diff") or active damping devices (CDC).

• – Ermitteln, auf Basis von für Fahrereingaben und/oder Fahrzustandsparameter charakteristischen Eingangssignalen, eines zur Erzielung einer gewünschten Fahrzeugbewegung erforderlichen Fahrzeuggiermomentes, und
• – Festlegen, in Abhängigkeit vom aktuellen Fahrzustand, des jeweiligen Beitrages sowohl der ESP-Aktuatoren als auch des wenigstens einen AFS-Aktuators zur Erzeugung dieses Fahrzeuggiermomentes.

The invention further relates to a vehicle motion control method in a vehicle, the vehicle having an ESP system with ESP actuators for selectively braking individual wheels of the vehicle and an AFS system having at least one AFS actuator for controlling the steering angle of wheels of the vehicle the method comprising the steps of:

• Determining, on the basis of input signals characteristic of driver inputs and / or driving state parameters, a vehicle yawing moment required to achieve a desired vehicle movement, and
• - Set, depending on the current driving condition, the respective contribution of both the ESP actuators and the at least one AFS actuator for generating this Fahrzeuggiermomentes.

Further Embodiments are the description and the dependent claims refer to.

The Invention will be described below with reference to a preferred embodiment with reference to the attached figure in more detail explained.

1 shows the structure of an inventive arrangement for active yaw control with integration of an AFS system and an ESP system according to an embodiment of the present invention.

According to 1 receives a driver input evaluation unit 10 for evaluation of driver input signals 5 which may in particular comprise a steering angle predetermined by the driver, the vehicle speed and additionally further signals. Based on these input signals 5 identifies the driver input evaluation unit 10 the driver's intended path of the vehicle and calculates a yaw rate setpoint.

This yaw rate set point is sent to a vehicle yaw control unit 20 (VYC = "vehicle yaw controller") which calculates a suitable vehicle yaw moment required to minimize the deviation between the yaw rate setpoint and the actual yaw rate value of the vehicle.

The vehicle yaw control unit 20 determined required Fahrzeuggiermoment is then by means of a distribution unit 30 distributed to the AFS actuators and the ESP actuators, ie it will be the contributions of the AFS actuators and the ESP actuators in the generation of the required vehicle giermomentes determined. The corresponding activation of the AFS actuators and the ESP actuators takes place in a hardware block 50 which is in 1 is shown only schematically and an ESP control 51 and an AFS driver 52 having.

sensors 60 serve to detect the current driving condition and to transmit corresponding sensor signals to the driver input evaluation unit 10 to the vehicle yaw control unit 20 and to a further explained in more detail unit 40 for determining a tire gradient signal characteristic of a relative change in the contact surface forces of the tires of the vehicle with respect to steering and braking interventions.

The distribution of the required vehicle yaw moment is determined by solving a constrained least squares optimization problem, ie, an error squares optimization problem with constraints. This least squares optimization problem can be formulated as follows:

In this case, A _{act2body denotes} a matrix which will be explained in more detail below, which relates the actuator _forces to the vehicle body forces, and F _act denotes the actuator forces required for the required steering actions on the front wheels and the required braking actions on each wheel.

• – Fahrzeuggiermoment-Anforderungssignal: Das Fahrzeuggiermoment-Anforderungssignal stellt das erforderliche, auf das Kraftfahrzeug einwirkende Giermoment dar. Dabei ist das Fahrzeuggiermoment-Anforderungssignal insofern inkrementell, als es nicht das absolute Giermoment angibt, sondern ein zusätzliches Giermoment bezogen auf den tatsächlichen bzw. aktuellen Fahrzeugzustand bzw. Zeitpunkt.
• – Lenk-Brems-Verteilungssignal (optional): Das Lenk-Brems-Verteilungssignal steht für eine geforderte Verteilung auf die Lenkaktuatoren und die Bremsaktuatoren. Das Lenk-Brems-Verteilungssignal ist durch die Größe der Fahrzeuggiermoment-Anforderung bestimmt, welche durch Einsatz von Lenkeingriffen erzeugt werden soll. Beispielsweise entspricht ein Wert des Lenk-Brems-Verteilungssignals von 100% dem ausschließlichen Einsatz von Lenkaktuatoren, und ein Wert des Signals von 0% entspricht dem ausschließlichen Einsatz von Bremsaktuatoren.
• – Brems-Verteilungssignal (optional) Das Brems-Verteilungssignal steht für die erforderliche Verteilung der Bremskräfte auf die Vorderachse und die Hinterachse. Das Brems-Verteilungssignal ist definiert durch die Größe des Giermomentes, welches an der Vorderachse erzeugt werden sollte. Beispielsweise entspricht ein Wert des Brems-Verteilungssignals von 100% einem ausschließlich an der Vorderachse vorgenommenen Bremsvorgang, und ein Wert des Signals von 50% entspricht einem gleichermaßen an der Vorderachse und der Hinterachse vorgenommenen Bremsvorgang.
• – Längskraft-Anforderungssignal (optional) Das Längskraft-Anforderungssignal steht für eine erforderliche Bremskraft auf das Fahrzeug (d. h. eine negative Beschleunigung). Idealerweise sollte das Längskraft-Anforderungssignal Null betragen, da eine Verzögerung bzw. Geschwindigkeitsverringerung aufgrund von Bremseinwirkungen minimiert werden sollte. Es kann jedoch in bestimmten Situationen aus Sicherheitsgründen erforderlich sein, die Fahrzeuggeschwindigkeit rasch zu reduzieren.

F _body denotes the required body force, which is composed of the following signals:

• Vehicle yaw moment request signal: The vehicle yaw moment request signal represents the required yaw moment acting on the motor vehicle. The vehicle yaw moment request signal is incremental insofar as it does not indicate the absolute yaw moment but an additional yaw moment related to the actual vehicle state Time.
• - Steering-Brake Distribution Signal (optional): The steering-brake distribution signal represents a demanded distribution on the steering actuators and the brake actuators. The steering brake distribution signal is determined by the magnitude of the vehicle yaw moment request to be generated by using steering interventions. For example, a value of the steering brake distribution signal of 100% corresponds to the exclusive use of steering actuators, and a value of the signal of 0% corresponds to the exclusive use of brake actuators.
• - Brake distribution signal (optional) The brake distribution signal represents the required distribution of braking forces on the front and rear axles. The brake distribution signal is defined by the magnitude of the yaw moment that should be generated at the front axle. For example, a value of the brake distribution signal of 100% corresponds to a braking operation made exclusively on the front axle, and a value of the signal of 50% corresponds to a braking operation made equally on the front axle and the rear axle.
• Longitudinal force request signal (optional) The longitudinal force request signal represents a required braking force on the vehicle (ie, a negative acceleration). Ideally, the longitudinal force request signal should be zero because deceleration due to braking effects should be minimized. However, in certain situations, for safety reasons, it may be necessary to reduce vehicle speed rapidly.

Of all the vehicle body force request signals, the vehicle yaw request signal is the most important. The remaining request signals may be disabled in a default setting. In this situation, the distribution is completely determined by the calculated tire gradients. This means that the most efficient actuators to control the yawing behavior of the vehicle are used. The further request signals, ie the steering brake distribution _signal , the brake distribution _signal and the longitudinal force request _signal , can be used together with the actuator _{limit values} F _act.min and F _act.max to further the performance or the operating _{behavior of} the control arrangement Boundary conditions such. B. adjust the ride comfort, handling characteristics and subjective driving experience.

The actuator forces are given by F _act = [Δδ _F , ΔF _{x, FL} , ΔF _{x, FR} , ΔF _x , R L, ΔF _{x, RR} ] and represent the required steering inputs at the front wheels and the required braking actions at each wheel the braking actions are also formulated instead of a change in the longitudinal force via changes in the longitudinal brake slip.

The matrix A _act2body represents a matrix that _relates the actuator forces to the vehicle body forces. This matrix is determined by means of the geometric information about the vehicle and the tire gradients which are calculated during operation (online) from a static / dynamic tire model in the tire gradient calculation (CPFD).

According to 1 the arrangement further has a unit 40 for determining a tire gradient signal characteristic of a relative change in the contact surface forces of the tires of the vehicle with respect to steering and braking interventions and for transmitting this tire gradient signal to the distribution unit 30 on. The tire gradients represent the relative change in contact surface forces with respect to steering and braking interventions. The matrix is thus variable in time as it changes with a change in driving conditions. This tire model used to calculate tire gradients requires only detection of tire non-linearity and qualitative behavior but not quantitative behavior.

The magnitudes F _act.min and F _act.max represent the lower and upper limits for steering and braking interventions, respectively. These signals can be used to _{impart actuator} limits or advance ("a priori") vehicle _dynamics information implement (for example: "no braking on the rear wheels in situations with oversteer").

One Example of an implementation of actuator limits is shown in Table 1.

Table 1:

In the handling area, according to Table 1, only steering interventions are used to control the yaw behavior of the vehicle. In the stability area, according to Table 1, both steering and braking interventions are used to control the vehicle movement. The steering interventions are used as long as the lateral slip angle α _{F is} smaller than α _S. The value α _S represents the value of the wheel slip angle at which the lateral tire forces transition into saturation. This means that the driver is protected from understeer situations, because when the saturation limit is exceeded, typically at a value of α _S = 10 °, additional steering interventions are used to reduce lateral "lateral slip" ,

The method according to the invention for yaw control can be extended in a simple way to the effect that different active suspension systems (E-Diff, CDC) can be provided. Although in the method of the invention according to the described embodiment, the required longitudinal braking forces are calculated at the wheels, by means of a change of the actuator _limits , ie of F _act.min and F _act.max , also traction _forces from a differential gear can be taken into account.

In summary, the inventive method for realizing an integration in akti gearing systems with regard to steering and braking interventions. The method improves overall control performance by utilizing synergy between the steering actuators and the brake actuators (ie, by coupling longitudinal and lateral tire forces). Furthermore, the method according to the invention simplifies optimization of the control system with respect to the requirements both with regard to the driving behavior and the subjective driving sensation. The modular design increases flexibility and compatibility of the arrangement according to the invention.

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

• EP 1447262 A1 [0006]
• - DE 102005015241 A1 [0007]

Claims (7)

Arrangement for vehicle movement control in a vehicle, the vehicle having an ESP system with ESP actuators for selectively braking individual wheels of the vehicle and an AFS system with at least one AFS actuator for controlling the steering angle of wheels of the vehicle, characterized by a vehicle Yaw control unit ( 20 ), which are based on input signals characteristic of driver inputs and / or driving state parameters ( 5 ) determines a vehicle yaw moment required to achieve a desired vehicle movement; and a distribution unit ( 30 ), which determines depending on the current driving state, the respective contribution of both the ESP actuators and the at least one AFS actuator for generating the Fahrzeuggiermomentes. Arrangement for vehicle movement control, according to claim 1, characterized in that the arrangement further comprises a unit ( 40 ) for determining a tire gradient signal characteristic of a relative change in the contact surface forces of the tires of the vehicle with respect to steering and braking interventions and for transmitting this tire gradient signal to the distribution unit ( 30 ) having. Arrangement for vehicle movement control, according to claim 1 or 2, characterized in that this in both a handling mode as well as in a stability mode is operable, wherein in the handling mode, only the at least one AFS actuator for generation contributes the Fahrzeuggiermomentes and wherein in the stability mode both the at least one AFS actuator and at least one the ESP actuators contributes to the generation of the Fahrzeuggiermomentes. Arrangement for vehicle movement control, according to one of claims 1 to 3, characterized in that the distribution unit ( 30 ) is configured to determine the contribution of both the ESP actuators and the at least one AFS actuator by solving a least squares optimization problem with constraints. Arrangement for vehicle movement control, according to claim 4, characterized in that this least-squares optimization problem can be represented as:

where A _{act2body denotes} a _{matrix describing} the relationship between the actuator forces exerted by the AFS actuator (s) and the vehicle body forces, where F _{act designates} the necessary steering inputs on the front wheels and the required braking interventions on each wheel necessary actuator forces, and where F _act.min , F _{act.max represent} a lower or an upper limit for steering and braking interventions. Arrangement for vehicle movement control, according to claim 5, characterized in that the lower limit value F _act.min and the upper limit value F _{act.max are} variably adjustable. A method of vehicle motion control in a vehicle, the vehicle having an ESP system with ESP actuators for selectively braking individual wheels of the vehicle and an AFS system having at least one AFS actuator for controlling the steering angle of wheels of the vehicle, characterized in that the method comprises the following steps: determining, based on input signals characteristic of driver inputs and / or driving state parameters ( 5 ), a Fahrzeuggiermomentes required to achieve a desired vehicle movement; and determining, depending on the current driving state, the respective contribution of both the ESP actuators and the at least one AFS actuator for generating this vehicle yaw moment.