DE102014208625A1 - Method for regulating the driving dynamics of a motor vehicle - Google Patents

Abstract

The invention relates to a method for controlling the driving dynamics of a motor vehicle having an electronic brake system with independently controllable wheel brakes on all wheels and / or a driver-independent adjustable electronic steering, wherein an actual driving state and a target driving state of the motor vehicle are determined, and wherein the electronic brake system and / or the electronic steering system are controlled to influence the driving state when an unstable driving situation has been detected, the motor vehicle having at least one optical sensor connected in fixed alignment with the motor vehicle, having image data of an image of at least one stationary object point Outside space of the motor vehicle are detected. According to the invention, at least one vehicle dynamic quantity is determined in the determination of the actual driving state on the basis of a determination of at least one geometric variable on the basis of the optical sensor with the steps: exposing the sensor for a predefined period of time, finding a highlight, and determining a value for the vehicle dynamic variable a track caused by the highlight. Furthermore, the invention relates to a system for stabilizing a motor vehicle.

Description

The invention relates to a method for controlling the driving dynamics of a motor vehicle according to the preamble of claim 1 and to a system for stabilizing a motor vehicle according to the preamble of claim 9.

Vehicle dynamics control systems in modern vehicles use sensors to record vehicle movements and evaluate them using models in order to detect an unstable driving situation in which the vehicle only follows the driver's instructions to a limited degree or not at all. When such an unstable driving situation, such as a skid of the vehicle, has been determined stabilizes a vehicle dynamics control system whose structure, for example, from EP 0 792 229 B1 the vehicle is known by braking and / or steering interventions. The sensors of the vehicle dynamics control systems generally comprise wheel speed sensors, a longitudinal and / or lateral acceleration sensor, a yaw rate sensor and a steering angle sensor. In many cases, a control of the float angle velocity takes place, since it can be well determined on the basis of the sensor signals. A calculation of the slip angle by integration has the disadvantage of being particularly error-prone, since, inter alia, due to the contributions of constants to the integral large errors can occur.

In addition, vehicles are increasingly equipped with driver assistance systems in which the environment of the vehicle is detected by means of optical sensors, for example, to automatically adapt the vehicle speed to the speed of a preceding vehicle or an imminent collision of the vehicle with an object in the vicinity of the vehicle early to recognize and to initiate measures to avoid the collision.

From the DE 10 2006 036 921 A1 a method for stabilizing a motor vehicle is known in which image data of an image of at least one stationary object point having outer space of the motor vehicle are detected by means of a fixed alignment with the motor vehicle associated optical sensor at a first time and at a second time. Based on a comparison of the image data acquired at the first time and the image data acquired at the time, a lateral velocity and / or a yaw angle change of the motor vehicle are determined. On the basis of the determined lateral velocity and / or yaw angle change, a driving state of the motor vehicle is evaluated, and depending on a result of the evaluation, the driving state of the motor vehicle is influenced.

The object of the present invention is to provide a simple and preferably quickly executable method for driving dynamics control and a system suitable for carrying out the method.

According to the invention, this object is achieved by a method having the features of claim 1 and by a device having the features of claim 9.

• • Belichten des Sensors für eine vorgegebene Zeitdauer,
• • Suchen eines Glanzpunkts, und
• • Ermitteln eines Werts für die fahrdynamische Größe anhand einer Bestimmung mindestens einer geometrischen Größe einer durch den Glanzpunkt verursachten Spur

durchgeführt werden.Thus, a method is provided for regulating the driving dynamics of a motor vehicle, which has an electronic brake system with driver-independently controllable wheel brakes on all wheels and / or a driver-independently adjustable electronic steering, wherein an actual driving state and a target driving state of the motor vehicle are determined, and wherein the electronic brake system and / or the electronic steering are controlled to influence the driving condition when an unstable driving situation has been detected based on an assessment of the actual driving state of the motor vehicle, wherein the motor vehicle has at least one connected in fixed alignment with the motor vehicle optical sensor at the image data of an image of at least one stationary object point having outer space of the motor vehicle are detected. According to the invention, at least one vehicle-dynamic variable is detected in the determination of the actual driving state on the basis of the optical sensor, wherein the steps

• Exposure of the sensor for a predetermined period of time,
• • Find a highlight, and
• Determining a value for the dynamic driving quantity based on a determination of at least one geometric size of a track caused by the highlight

be performed.

An unstable driving situation can be detected according to known criteria. For example, a deviation between a measured yaw rate characterizing the actual driving state and a target yaw rate determined in particular on the basis of a vehicle model and driver specifications such as the steering angle can be considered, an unstable driving situation being recognized as detected if this deviation exceeds a predetermined threshold value. Alternatively, it can be evaluated or checked to detect an unstable driving state, whether the slip angle β and / or the float angle velocity amount exceed a predetermined threshold. Thus, based on a comparison between desired and actual driving state or alone based on an assessment of the actual driving state an unstable Driving situation are detected. By braking and / or steering interventions then takes place an influence on the driving condition to ensure the driving stability or to restore a stable driving situation.

An object point is expediently to be understood as meaning a point of an object detected by the optical sensor in the exterior of the vehicle. The image coordinates of the object point indicate the position of the object point or the image of the object point within a captured image. For example, in a rasterized image consisting of a plurality of pixels, the image coordinates correspond to the coordinates of the pixel containing the object point. The change in the image coordinates of an object point indicates the movement of the object point through the image or the image plane, which can also be referred to as the optical flow of the object point.

A highlight is preferably recognized by the fact that the intensity detected during the exposure time exceeds a predetermined intensity threshold and the extent is at least one dimension below a predetermined expansion threshold. If an optical sensor connected in fixed alignment with the vehicle-in particular a camera-is directed perpendicularly to the ground, then a nearly point-like high-intensity light source causes a track which at least approximately has the shape of a line.

Due to the fact that the at least one vehicle-dynamic variable is detected in the determination of the actual driving state on the basis of the optical sensor, a vehicle dynamics control can be realized with increased reliability and / or extended functionality. An evaluation of one or more highlights of an image taken with an optical sensor has the advantage that model-independent and with little computational effort also driving dynamics variables such as the slip angle and / or the lateral velocity can not be detected, the direct measurement by means of the usual sensors of a vehicle dynamics control are accessible. Especially when at least a partial area of the optical sensor looks perpendicular or almost perpendicular to the ground, the evaluation can be carried out with a very low computational effort.

With regard to a particularly reliable determination of the driving dynamics / n size / n, it is advantageous if at least two, preferably at least ten, highlights are considered, and if a plausibility and / or averaging between the determined from a consideration of the various highlights driving dynamics size / n takes place.

It is expedient if the predetermined time duration is set in accordance with a vehicle speed detected by at least one independent sensor, in particular at least one wheel speed sensor and / or a satellite navigation system, and / or the predetermined time duration is set on the basis of a mathematical function of predetermined periodicity. By determining and / or adjusting the predefined time duration on the basis of the vehicle speed detected by one of these sensors, it can be ensured that the trace of a highlight under the current driving conditions has particularly suitable dimensions on the sensor surface or the image with respect to an evaluation. A mathematical function of predetermined periodicity makes it possible, in particular, to set intermittently different exposure times or predetermined time periods, and thus to avoid or detect undetected aliasing. Due to the fact that the exposure time is predetermined from the outside, the optical sensor, in particular a camera, can be constructed particularly simply and / or the control or evaluation can be carried out with a particularly low computational outlay.

An exposure of the sensor for a predetermined period of time preferably also comprises an addition of a plurality of successively acquired images of the optical sensor whose exposure time corresponds to a portion of the predetermined time duration. Frequently, optical sensors or cameras are used to record a film, ie images are taken at regular intervals with an optionally dependent on the recorded scene, but limited in each case by the repetition frequency exposure time. In order to obtain a picture which is well suited for the evaluation or determination of the dynamic driving quantity, the addition of several successive pictures is useful.

Appropriately, an alignment of the optical sensor is determined with respect to the vehicle longitudinal axis, wherein at least one independent sensor, in particular a steering angle sensor and / or a yaw rate sensor and / or a lateral acceleration sensor, a straight-ahead driving is detected, and wherein the orientation of the optical sensor in accordance with at least one detected during a recognized straight ahead driving image. Especially when the optical sensor detects the roadway only in the edge region, so that it can lead to optical distortions, offers such a calibration of the sensor position. By at a Driving straight ahead, ie detecting and evaluating one or more highlights of a defined driving situation, the alignment of the sensor can be determined simply and reliably.

Preferably, the slip angle is determined as a dynamic driving variable, wherein for determining the current slip angle, the geometric size of an angle between the track, which has at least approximately the shape of a line, and a predetermined direction is determined. Advantageously, a float angle is determined in this development, which can be used as a control variable for a float angle control. In contrast to the procedure in known vehicle dynamics regulations, in which usually model-based methods are provided for estimating the slip angle, the slip angle is also determined here model-independent.

In particular, the slip angle is used to determine a slip angle of at least one wheel of the motor vehicle. As is known, the slip angle of a wheel causes a cornering force acting on the wheel which keeps the motor vehicle on its path when cornering. From a certain maximum value of the slip angle, however, the wheels start to slide. The cornering force can then no longer be increased, but decreases even with increasing skew angle slightly. As a result, the motor vehicle becomes unstable and may be skidding.

An embodiment of the method and the vehicle dynamics control system therefore includes that the slip angle is compared with a maximum value, and that the speed of the motor vehicle is reduced when the slip angle is greater in magnitude than the maximum value. By reducing the vehicle speed, which can be carried out for example by reducing the engine torque provided by the drive motor of the motor vehicle and / or by a brake intervention, the lateral drift of the vehicle is reduced and stabilizes the vehicle.

It is advantageous if the maximum value corresponds to a slip angle at which a cornering force of the wheel is almost maximum or a little smaller than the slip angle at which the maximum cornering force can be built so that the cornering force potential is not fully utilized and any time Safety reserve is available. Since the maximum build-up cornering force is significantly influenced by the present road friction coefficient, it is particularly advantageous if the maximum value is determined as a function of a road friction coefficient.

Alternatively, or in addition to a determination of the slip angle, it is advantageous if a determined driving dynamic variable is the speed above the ground, wherein for determining the speed above the ground, the geometric size is a length of the track, which has at least approximately the shape of a line , Preferably, a longitudinal and a transverse speed of the vehicle are determined from the length and an angle between the track and a predetermined direction.

In the determination of the actual driving state, therefore, a float angle of the motor vehicle is preferably determined directly or from a consideration of longitudinal and transverse speed, wherein preferably a yaw rate of the motor vehicle is detected independently of image data by means of a yaw rate sensor, and the driving state of the motor vehicle is dependent on the determined slip angle. The fact that a model-independently determined slip angle and an independently measured yaw rate are considered, a particularly reliable determination of the actual driving state is ensured. Thus, a control in accordance with the float angle is possible, and a variety of critical driving situations can be detected early and / or defused or regulated.

In one refinement of the method and vehicle dynamics control system, it can be provided that an optical flow within the images is determined on the basis of changes in image coordinates of a plurality of object points, that the optical flow serves as an input variable for a Kalman filter, wherein the Kalman filter uses the a movement state of the motor vehicle is estimated optical flow and wherein in particular the lateral velocity and / or the yaw angle change is determined on the basis of the estimated state of motion of the motor vehicle.

Based on the optical flow within the entire image data, a three-dimensional representation of the exterior of the motor vehicle and the movement of the vehicle through the exterior space can be determined, whereby the determination of the state of motion of the motor vehicle is possible. Advantageously, a Kalman filter is used for this purpose. Particularly preferably, the signals of the yaw rate sensor are used to evaluate the image data in order to determine the lateral velocity of the motor vehicle. As a result, considerably less computing power is required for the evaluation of the image data.

The invention further relates to a system for stabilizing a motor vehicle, which has at least one optical sensor connected in fixed alignment with the motor vehicle, an electronic brake system with driver-independent controllable wheel brakes on at least two wheels and / or a driver-independently adjustable electronic steering, with an electronic control unit having at least one arithmetic unit, which evaluates the actual driving state of the motor vehicle based on the data of at least the optical sensor and the electronic brake system and / or electronic steering controls to influence the driving condition, if the evaluation has resulted in an unstable driving condition. According to the invention, the optical sensor sees a viewing angle, which includes the environment before, next to or behind the motor vehicle, the data of the at least one optical sensor for a comfort function such as a digital side mirror, a rear view camera, a wiper operation in the event of moisture Emergency brake assist and / or a distance control to the preceding traffic are used. The arithmetic unit preferably carries out a method according to the invention for stabilizing the driving behavior of a motor vehicle.

The invention makes it possible to use optical sensors which show a growing equipment rate in motor vehicles, advantageously also in the context of a vehicle dynamics control, whereby the functions of the vehicle dynamics control can be improved and extended. In particular, this makes it possible to calculate a float angle independently of the model. Thus, a reliable float angle control and / or determination and limitation of a slip angle of at least one wheel can take place.

According to a preferred embodiment of the invention, a partial surface of the optical sensor via at least one arranged in the beam path optical element, in particular a mirror and / or a prism and / or a glass fiber, a second angle, which in particular includes a road surface, preferably the evaluation the driving state is based on this partial area of the optical sensor. Thus, no additional optical sensor is required, but an already existing sensor, which is aligned or designed, for example, for a driver assistance function, can additionally be used for vehicle dynamics control. The additional optical element arranged in the beam path causes comparatively low costs and can preferably already be integrated during the production of the optical sensor.

According to a particularly preferred embodiment of the invention, the vehicle dynamics control system or system for stabilizing a motor vehicle additionally comprises an electrically controllable light source, in particular an infrared light emitting diode, which is directed to the surrounding area encompassed by the second viewing angle of the optical sensor, wherein in particular a drive in accordance with a Comparison of the built-in over the subarea sensor signal is carried out with a darkness threshold. Thus, a suitable illumination of the evaluated for the determination of driving dynamics variables partial area of the optical sensor can be ensured. The dynamic driving quantity (s) can be determined independently of the ambient conditions.

According to a further preferred embodiment of the invention, the optical sensor is movably suspended via one or more magnetic coils or piezocrystals, which are preferably controlled on the basis of the signals of an acceleration sensor in order to stabilize the sensor against shocks. Thus, an error caused by shocks of the optical sensor can be avoided and also on bad roads reliable detection of driving dynamics variables based on the optical sensor is possible.

Further preferred embodiments will become apparent from the subclaims and the following description of an embodiment with reference to a figure.

It shows

1 a schematic representation of a motor vehicle with an optical sensor.

1 shows a schematic representation of a motor vehicle 1 with an optical sensor 15 , which is suitable for carrying out the method according to the invention or has a system according to the invention for stabilizing the motor vehicle. It has a drive motor 2 driving the wheels of one or more axles of the vehicle, a steering wheel 3 , a brake pedal 4 , which with a tandem master cylinder (THZ) 13 is connected, and four individually controllable wheel brakes 10a - 10d on. In addition to or as an alternative to hydraulic friction brakes, electromechanically actuated friction brakes can also be used as wheel brakes on one, several or all wheels. If the vehicle has at least one electric drive, the braking torque at the wheel (s) connected to an electric drive can be generated at least partially by the electric drive machine (s) operated as a generator.

The steering wheel 3 is connected via a steering line, not shown, with the wheels of the front axle, so that the steering angle of the front wheels can be selected depending on the rotation of the steering wheel. The steering column has an electric power steering on, so that a mechanically connected electric motor in addition to the manual steering torque of the driver can apply an additional torque on the steering line to relieve the driver while steering and / or deliver a steering recommendation in a predetermined by the control unit of the power steering direction or a steering in one difficult to steer unfavorable steering direction. The power steering control unit is connected via a vehicle data bus with one or more other electronic control units, wherein in particular the electronic control unit (ECU) 7 a braking system can request an additional torque via an interface.

For the detection of driving dynamic conditions are a steering wheel angle sensor 12 for measuring the steering angle δ, four wheel speed sensors 9a - 9d for measuring the rotational speeds V _{i of} the individual wheels, a lateral acceleration sensor 5 for measuring the lateral acceleration a _Lat , a yaw rate sensor 6 for measuring the yaw rate auch, also called the yaw rate. and at least one pressure sensor 14 for the measurement of the brake pressure generated by brake pedal and THZ p exist. In this case, the pressure sensor 14 be replaced by a Pedalweg- or pedal force sensor, if the auxiliary pressure source is arranged such that a brake pressure built up by the driver of the auxiliary pressure source is indistinguishable or an electromechanical brake actuator is used with known relationship between pedal position and braking torque. The signals from the wheel sensors are sent to the electronic control unit (ECU) 7 supplied to the braking system, which determines the vehicle speed v _Ref based on predetermined criteria from the Raddrehgeschwindigkeiten V _i .

The ECU 7 receives the data of the above-described as well as possibly existing further sensors and controls the hydraulic unit (HCU) 8th to allow a driver independent of a structure or a modulation of the brake pressure in the individual wheel brakes. In addition, the current of drive motor 2 generated driving torque and the torque desired by the driver determined. These may also be indirectly determined variables derived, for example, from an engine map and the ECU 7 via an interface 11 a vehicle data bus, such as a CAN or FlexRay bus, are transmitted from the engine control unit, not shown.

The ECU 7 Often executes several methods for controlling the driving stability, wherein an arbitration takes place if necessary simultaneously arriving braking requirements. Thus, a yaw rate control often compares the measured yaw rate with a model yaw rate. If this difference lies above the control entry threshold, the brake intervention begins. The model yaw rate corresponds to the desired yaw rate and is formed by a simple vehicle model via the steering angle and vehicle speed. In addition, there is often a regulation of the float angle velocity. This size is also formed on the vehicle model and corresponds in oversteer situations the speed at which the vehicle rotates or the vehicle rear shears off. Once a certain threshold for the Schwimmwinkelgeschwindigkeit is exceeded, the brake intervention begins. Most widely used is a brake slip control which prevents the wheels from locking during braking.

Furthermore, the vehicle 1 an environment sensor with at least one environment sensor 15 on, with the objects in the environment of the vehicle can be detected. ambient sensor 15 can objects in a detection area 17 recognize that a solid angle in front of the vehicle 1 includes, in which an object 18 is shown by way of example. In the environment sensor 15 it is preferably a camera, which may for example be designed as a stereo camera to determine the distances d to the detected points of an object and the angle φ between the connecting line to these points and the central longitudinal axis of the vehicle, as shown in 1 for a point of the object 18 is illustrated. The signals of the environment sensor 15 be from a control computer 16 evaluated and corresponding information from the ECU 7 made available. In principle, control calculator 16 but also in the environment sensor 15 be integrated, and / or the ECU 7 can process the sensor signals directly.

For the method according to the invention, it is necessary that at least one partial area of the optical sensor 15 the road or individual stationary points maps. This can be ensured in particular by the fact that in the beam path of the sensor 15 an additional optical element is arranged, which images a section of the road surface on a partial surface of the sensor. To realize such an optical element is on the US 8541 732 B2 or the EP 2 557 414 A2 directed.

In a method according to the invention, therefore, an exposure of the environment sensor for a predetermined period of time initially takes place.

Subsequently, at least one highlight is sought, which has a small spatial extent and a very high intensity. For example, it may also be provided to consider the ten brightest highlights and an averaged value for the at least one to determine the driving dynamic size. If the predetermined time period has been suitably selected, a highlight on the image causes a track whose length is a measure of the speed of the vehicle and whose angle to the longitudinal direction of the vehicle allows a direct determination of the slip angle β. If it is determined from a consideration of the highlights that the track for an accurate determination of the slip angle is too short, the predetermined time period is expediently adapted for the next exposure, ie extended. Accordingly, a shortening of the predetermined period of time can also be carried out if, for example, a track, ie essentially a line, extends over the entire extent of the sensor.

If, for example, based on the steering wheel angle sensor 12 and the yaw rate sensor 6 a straight-ahead drive has been detected, it is expedient to check and / or calibrate the orientation of the sensor so that the longitudinal direction as the reference axis for the slip angle is correct. In addition, it can be provided to undertake a correction of the distortion of the objective of the camera or the optical sensor from a view of successive images. Thus, by means of a comparison of the highlights in the first image and in the second image, a coordinate transformation can be carried out according to the method of the least square error.

gegeben ist. Hierbei bezeichnet v_x die Längsgeschwindigkeit des Fahrzeugs, die aus den Signalen der Raddrehzahlsensoren bestimmt werden kann. Alternativ kann der Schwimmwinkel auch direkt aus einer Betrachtung der Spur eines Glanzpunkts als Winkel zwischen Spur und Längsachse des Fahrzeugs bzw. der entsprechende Achse des Sensorbilds ermittelt werden. A transverse velocity v _y determined on the basis of image data can be used, in particular, to calculate the slip angle β of the vehicle which passes through

given is. Here, v _x denotes the longitudinal speed of the vehicle, which can be determined from the signals of the wheel speed sensors. Alternatively, the slip angle can also be determined directly from a consideration of the trace of a highlight as an angle between the track and the longitudinal axis of the vehicle or the corresponding axis of the sensor image.

The slip angle β can be used to carry out a float angle control known to those skilled in the art, with which the yaw rate control is usually combined in vehicle dynamics control systems. In this case, regulating interventions are carried out, for example, when the slip angle β and / or the float angle velocity exceed a predetermined threshold value. An example of a combined yaw rate and slip angle control is approximately in the German Offenlegungsschrift DE 195 15 051 A1 described in this context.

Furthermore, a functional module is preferably provided in which the slip angle of the front and rear wheels of the vehicle is determined from the determined slip angle β 1 is calculated. For the slip angle α _{V of} the front wheels:

berechnet. Die Gierrate Ψ . wird zweckmäßigerweise durch einen Gierratensensor erfasst. Mit δ ist der an den Vorderrädern eingestellte Lenkwinkel bezeichnet, der mit dem Lenkwinkelsensor 12 erfasst wird. Bei den Größen l_V bzw. l_H handelt es sich um den in Fahrzeuglängsrichtung gemessenen Abstand zwischen den Mittelpunkten der Vorderräder bzw. der Hinterräder und dem Fahrzeugschwerpunkt. Dies sind im Wesentlichen konstante Größen, die in einem Speicher eines elektronischen Steuergeräts hinterlegt werden können. Ein von null verschiedener Schräglaufwinkel α an einem Rad führt dazu, dass an dem Rad eine Seitenführungskraft F_y aufgebaut wird. Vergrößert der Fahrer durch Einlenken den Schräglaufwinkel, so steigt die Seitenführungskraft F_y zunächst mit dem Schräglaufwinkel α auf ein Maximum an. Bei sich weiter erhöhendem Schräglaufwinkel kann die Seitenführungskraft F_y nicht weiter erhöht werden bzw. sinkt bei großen Schräglaufwinkeln α wieder leicht ab. Dies ist darauf zurückzuführen, dass der Reifen bei großen Schräglaufwinkeln α ins Gleiten gerät. Somit ist es vorteilhaft, das Fahrzeug mittels eines Eingriffs zu stabilisieren, wenn der Schräglaufwinkel α einen vorgegebenen Grenzwert überschreitet, der insbesondere anhand eines ermittelten Fahrbahnreibwerts μ angepasst werden kann.The slip angle α _H is determined by the equation

calculated. The yaw rate Ψ. is suitably detected by a yaw rate sensor. With δ the steering angle set at the front wheels is designated, which with the steering angle sensor 12 is detected. The quantities l _V and l _H are the distance measured in the vehicle longitudinal direction between the centers of the front wheels or the rear wheels and the vehicle center of gravity. These are essentially constant quantities that can be stored in a memory of an electronic control unit. A non-zero skew angle α on a wheel causes a cornering force F _{y to be} built up on the wheel. Increases the driver by turning the slip angle, the cornering force F _{y increases} first with the slip angle α to a maximum. With a further increasing skew angle, the cornering force F _y can not be further increased or drops slightly again at large skew angles α. This is due to the fact that the tire is slipping at large slip angles α. Thus, it is advantageous to stabilize the vehicle by means of an intervention when the slip angle α exceeds a predetermined limit, which can be adjusted in particular on the basis of a determined road friction coefficient μ.

By combining a driving stability control with an environment sensor system, wherein from a consideration of the tracks of highlights at least one vehicle dynamics variable is determined, in particular the otherwise imprecisely known slip angle, the control of vehicle dynamics in a variety of driving situations can be done easily and quickly, so that the Ride comfort and driving safety are increased.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0792229 B1 [0002]
• DE 102006036921 A1 [0004]
• US 8541732 B2 [0038]
• EP 2557414 A2 [0038]
• DE 19515051 A1 [0043]

Claims (12)

Method for controlling the driving dynamics of a motor vehicle having an electronic brake system with independently controllable wheel brakes on all wheels and / or a driver-independently adjustable electronic steering, wherein an actual driving state and a target driving state of the motor vehicle are determined, and wherein the electronic brake system and / or the electronic steering are controlled to influence the driving state, if an unstable driving situation has been detected based on an assessment of the actual driving state of the motor vehicle, wherein the motor vehicle has at least one connected in fixed alignment with the motor vehicle optical sensor, in which image data of a picture At least one exterior object of the motor vehicle having a stationary object point is detected, characterized in that at least one vehicle dynamic variable is determined on the basis of the optical sensor when determining the actual driving state, wherein the steps • exposing the sensor for a predetermined period of time, • finding a highlight, preferably detecting a highlight that the intensity detected during the exposure time exceeds a predetermined intensity threshold, and in particular the expansion is at least one dimension below a predetermined expansion threshold, and Determining a value for the driving dynamics variable based on a determination of at least one geometric size of a track caused by the highlight be performed. A method according to claim 1, characterized in that the predetermined time period is set in accordance with a detected by at least one independent sensor, in particular at least one wheel speed sensor and / or a satellite navigation system, vehicle speed and / or the predetermined time period is set based on a mathematical function of predetermined periodicity. A method according to claim 1 or 2, characterized in that an orientation of the optical sensor is determined based on the vehicle longitudinal axis, wherein on the basis of at least one independent sensor, in particular a steering angle sensor and / or a yaw rate sensor and / or a lateral acceleration sensor, a straight-ahead driving is detected, and wherein the orientation of the optical sensor is determined in accordance with at least one detected during a straight-ahead driving image. Method according to at least one of the preceding claims, characterized in that an exposure of the sensor for a predetermined period of time also includes an addition of a plurality of sequentially acquired images of the optical sensor whose exposure time corresponds to a proportion of the predetermined period of time. Method according to at least one of the preceding claims, characterized in that a determined driving dynamic quantity is the slip angle, and that determines the geometric size of an angle between the track, which has at least approximately the shape of a line, and a predetermined direction to determine the current slip angle becomes. Method according to at least one of the preceding claims, characterized in that a determined driving dynamic quantity is the speed above the ground, and that for determining the speed above the ground, the geometric size is a length of the track which has at least approximately the shape of a line , Preferably, from the length and an angle between the track and a predetermined direction, a longitudinal and a transverse speed of the vehicle are determined. Method according to at least one of the preceding claims, characterized in that at least two, preferably at least ten, highlights are considered, and that a plausibility and / or averaging between the determined from a consideration of the various highlights driving dynamics size / n takes place. Method according to at least one of the preceding claims, characterized in that during the determination of the actual driving state, a slip angle of the motor vehicle is determined directly or from a consideration of longitudinal and lateral velocity, wherein preferably a yaw rate of the motor vehicle is detected independently of image data by means of a yaw rate sensor , And that the driving condition of the motor vehicle is influenced in dependence on the determined slip angle. System for stabilizing a motor vehicle which has at least one optical sensor connected in fixed alignment with the motor vehicle, an electronic brake system with wheel brakes controllable independently by drivers on at least two wheels and / or an electronically adjustable electronic steering, with an electronic control unit having at least one arithmetic unit , which evaluates the actual driving state of the motor vehicle based on the data of at least the optical sensor and the electronic Brake system and / or the electronic steering for influencing the driving state drives, if the evaluation has resulted in an unstable driving condition, characterized in that the optical sensor sees a viewing angle, which includes the environment before, next to or behind the motor vehicle, the data of the at least one optical sensor is also used for a comfort function such as a digital side mirror, a reversing camera, an operation of a windshield wiper in moisture, an emergency brake assist and / or a distance control to the preceding traffic, wherein the arithmetic unit preferably performs a method according to at least one of the preceding claims. System according to claim 9, characterized in that a partial surface of the optical sensor via at least one arranged in the beam path optical element, in particular a mirror and / or a prism and / or a glass fiber, a second viewing angle recognizes, which in particular comprises a road surface, preferably the evaluation of the driving state based on the partial surface of the optical sensor takes place. System according to claim 10, characterized by an electrically controllable light source, in particular an infrared light emitting diode, which is directed to the surrounding area from the second viewing angle of the optical sensor, wherein in particular a control in accordance with a comparison of the sensor integrated over the partial surface sensor signal is carried out with a darkness threshold , System according to one of claims 9 to 11, characterized in that the optical sensor is suspended movably via one or more magnetic coils or piezocrystals, wherein these are preferably controlled by the signals of an acceleration sensor in order to stabilize the optical sensor against shocks.

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