DE102018218926A1 - Driver assistance system - Google Patents

Abstract

Method for operating a driver assistance system for vehicles, which comprises the following steps: determining a section of road ahead which the vehicle will be driving in the immediate future; - Estimating a predictive wheel friction coefficient of the motor vehicle for the section of road ahead; - Estimating a permissible steering torque with which the vehicle can drive on the section of the road ahead; - Determining an actual steering torque of the vehicle; - Determining and executing a control command which sets the permissible steering torque if it is determined that the actual steering torque deviates from the permissible steering torque.

Description

The present invention relates to a method for operating a driver assistance system and a driver assistance system.

The DE 10 2012 112 725 A1 shows a method for estimating a predictive wheel friction value.

Against this background, the invention is based on the object of specifying a driver assistance system or a method for operating a driver assistance system by means of which a sporty driving style can be supported.

According to the invention, this object is achieved by a method for operating a driver assistance system with the features of patent claim 1 and / or by a driver assistance system with the features of patent claim 11.

• Ein Verfahren zum Betreiben eines Fahrerassistenzsystems für Fahrzeuge, welches die folgenden Schritte aufweist:
  • Ermitteln eines vorausliegenden Streckenabschnitts, der von dem Fahrzeug in unmittelbarer Zukunft befahren werden wird;
  • Schätzen eines prädiktiven Radreibwerts des Kraftfahrzeugs für den vorausliegenden Streckenabschnitt;
  • Schätzen eines zulässigen Lenkmoments, mit welchem das Fahrzeug den vorausliegenden Streckenabschnitt befahren kann;
  • Ermitteln eines tatsächlichen Lenkmoments des Fahrzeugs;
  • Ermitteln und Ausführen eines Steuerbefehls, welcher das zulässige Lenkmoment eingestellt, wenn festgestellt wird, dass das tatsächliche Lenkmoment von dem zulässigen Lenkmoment abweicht; sowie

Accordingly, it is provided:

• A method for operating a driver assistance system for vehicles, which has the following steps:
  • Determining a section of road ahead that the vehicle will be traveling in the immediate future;
  • Estimating a predictive wheel coefficient of friction of the motor vehicle for the preceding section of the route;
  • Estimating a permissible steering torque with which the vehicle can drive on the section of the road ahead;
  • Determining an actual steering torque of the vehicle;
  • Determining and executing a control command which sets the permissible steering torque if it is determined that the actual steering torque deviates from the permissible steering torque; such as

• Ein Fahrerassistenzsystem für ein Fahrzeug mit
• einer ersten Schnittstelle zu Mitteln zum Ermitteln eines vorausliegenden Streckenabschnitts, der von dem Fahrzeug in unmittelbarer Zukunft befahren werden wird,
• einer zweiten Schnittstelle zu Mitteln zum Schätzen eines prädiktiven Radreibwerts des Kraftfahrzeugs für den vorausliegenden Streckenabschnitt,
• einer Ermittlungseinheit zum Ermitteln eines tatsächlichen Lenkmoments des Fahrzeugs und
• mit einer Recheneinheit zum Schätzen eines zulässigen Lenkmoments, mit welchem das Fahrzeug den vorausliegenden Streckenabschnitt befahren kann, sowie zum Ermitteln eines Steuerbefehls, welcher das zulässige Lenkmoment einstellt.

It also provides:

• A driver assistance system for a vehicle with
• a first interface to means for determining a section of road ahead which the vehicle will be traveling in the immediate future,
• a second interface to means for estimating a predictive wheel friction value of the motor vehicle for the route section ahead,
• a determination unit for determining an actual steering torque of the vehicle and
• with an arithmetic unit for estimating a permissible steering torque with which the vehicle can drive the section of road ahead, and for determining a control command which sets the permissible steering torque.

Vehicles in the sense of this patent application are motor-driven land vehicles. Rail vehicles are also included.

A steering torque describes the steering effect of a steering force on a body. A permissible steering torque is a steering torque by means of which a section of the route can be driven by a vehicle without an accident. An actual steering torque of a vehicle is the steering torque that acts on the vehicle based on a specific steering setting.

Driver assistance is the support or replacement of a driver by additional electronic devices in motor vehicles. Safety aspects are often in the foreground, but the focus is also on increasing driving comfort or driving pleasure. Another aspect is the improvement in profitability.

A preceding section of a vehicle extends in front of a vehicle in the direction of travel and can have any length.

The wheel friction coefficient or coefficient of friction, also called the coefficient of friction, is a dimensionless measure of the frictional force in relation to the contact pressure between a wheel and a road surface. A predictive wheel friction value is a prediction of a wheel friction value for a section of the road ahead. A measured wheel friction value is a current or past wheel friction value that was measured or calculated by a sensor system.

A sensor, also known as a detector, (measurement variable or measurement) sensor or (measurement) sensor, is a technical component that has certain physical, chemical properties or states, e.g. B. temperature, humidity, pressure, speed, brightness, acceleration, pH value, ionic strength, electrochemical potential and / or the material nature of its environment can be recorded qualitatively or quantitatively. These quantities are recorded by means of physical or chemical effects and converted into a further processable electrical signal as sensor data.

Radar is the name for various detection and location methods and devices based on electromagnetic waves in the radio frequency range (radio waves). A radar device is a device that emits electromagnetic waves emits bundles, which receives and evaluates echoes reflected by objects. In this way, information about the objects can be obtained. The following information can be obtained from the received waves reflected by the object: the angle and the distance to the object, the relative movement between the transmitter and the object, the distance and the absolute speed of the object, contours or images of the object.

Lidar, also called ladar, is a method related to radar for optical distance and speed measurement as well as for remote measurement of atmospheric parameters. Instead of the radio waves as with radar, laser beams are used.

Position data are, for example, GPS data.

Road data is all data relating to a road, for example data on the course of the road, curve radii, data on the surface condition, data on the roadway width and the like.

A deceleration command is a command to decelerate one or more moving elements of a moving body. Accordingly, a deceleration command can be directed to a change in direction of a body and / or to a braking of the body. For example, a change of direction of a vehicle can be brought about by selectively decelerating wheels, for example at the rear right.

In contrast to this, in this patent application, vehicle braking means a reduction in the speed of the entire vehicle.

A steering command is directed to a change in direction of a vehicle. Steering forces can be transmitted to the wheels of the vehicle via a steering axis of a mechanical steering system and / or via actuators of an electronic steering system.

A lane change assistant is set up to actively support a driver during a steering maneuver, for example a lane change, by the lane change assistant determining suitable steering commands.

An interface is a device between at least two functional units on which an exchange of logical quantities, e.g. Data, or physical quantities, e.g. electrical signals, either unidirectional or bidirectional. The exchange can be analog or digital. The exchange can also be wired or wireless.

The basic idea of the invention is to support a sporty driving style depending on an estimated predictive wheel friction value. If the wheel friction coefficient is too low, it can lead to oversteer or understeer of the vehicle when cornering, for example. This causes numerous accidents.

The idea of the invention is to intervene in a driving maneuver if it is determined that a wheel friction coefficient is not sufficient for the driving maneuver to be carried out safely.

Advantageous refinements and developments result from the further subclaims and from the description with reference to the figures of the drawing.

According to a preferred development of the invention, the predictive wheel friction value is estimated using sensor data. These sensor data are e.g. B. camera data, radar data and / or lidar data. Accordingly, it can be provided that an upcoming route section is detected by means of an optical sensor, that is to say a camera, a radar sensor and / or a lidar sensor, and a wheel friction value of the upcoming route section is inferred on the basis of the optical sensor data for the upcoming route section. For example, in wet road conditions there are often reflections on the road surface that can be visually detected. Snow or ice on a road can also be visually detected. In addition, the wheel friction coefficient is often adversely affected by a poor road condition that is visually detectable.

According to a preferred development of the invention, the predictive wheel friction value is estimated using position data of the vehicle and known road data. Accordingly, it can be provided, for example, that a curve radius or a curve curvature of a route section is known and the wheel friction value is estimated on the basis of this for the route section. It goes without saying that other influencing factors, such as the weather conditions, can also be taken into account.

According to a preferred development of the invention, the control command has a deceleration command and / or a steering command. This means that a driver can be supported in a variety of ways.

It can be provided to assist the driver only with a steering command or a deceleration command for selectively decelerating a wheel. This option is preferable to vehicle braking because it is less in the individual driving style of the driver is intervened and the driver can accordingly experience a sporty driving style, provided that the upcoming section of the route can be driven safely with these means.

Accordingly, provision can be made to determine whether the permissible steering torque can be set without initiating vehicle braking. This is particularly advantageous for driver assistance systems in sports cars, since sporty driver assistance systems deliberately intervene as little as possible in a driver's driving style.

It may also be expedient to brake the vehicle if it is determined that the permissible steering torque cannot be set at a current speed of the vehicle. Accordingly, it can be provided that it is determined that a section of the road ahead cannot be driven at the current speed of the vehicle. Accidents can thus be avoided even if vehicle braking seems inevitable.

According to a preferred development of the invention, further control commands are determined by a lane change assistant on the basis of the estimated permissible steering torque. Accordingly, it can be provided that the method as described above interacts with a lane change assistant. Even if only small steering torques are usually required for lane change maneuvers, it sometimes happens that, for example, unfavorable weather conditions such as heavy aquaplaning or snow residues on road surfaces have such an unfavorable effect on wheel friction that additional deceleration commands and / or steering commands are required even for changing lanes.

For example, especially in central European winter, the roads are mostly cleared very well, so that there are no adverse effects on the coefficient of friction. As a result, these lanes are driven at normal speed. Nevertheless, snow remains often on, for example, delay strips, which often surprise a driver.

The method as described above makes it possible to deal with such situations in such a way that a driving style is only intervened when it is foreseeable that an upcoming section of the route cannot be driven safely.

According to a preferred development of the invention, the estimated predictive wheel friction value is checked for plausibility by means of a current or past wheel friction value. Accordingly, it can be provided that an estimated predictive wheel friction value is corrected on the basis of a difference between a previous predictive wheel friction value and a previous actual wheel friction value.

This allows errors to be reduced, even if they are of unknown cause.

According to a preferred development of the invention, it is determined whether an oncoming lane can be driven safely and the permissible steering torque is determined on the basis of this. For example, some curves can be driven at a higher speed if these curves are cut, i. H. if at least sections of a curve are partially driven on the opposite lane. Cutting curves is usually a deliberately initiated driving maneuver and is based on a conscious decision by a driver. Accordingly, drivers could find it annoying if a driver assistance system prevented the safe cutting of a curve.

In contrast, this further development of the invention creates an additional safety reserve when, for example, inconsiderable curves are cut. For example, it often happens that a driver is surprised by oncoming traffic in a cut curve and cannot avoid it safely, since the wheel friction coefficient would not be sufficient to change lanes back into one's own lane.

In such cases, it can be provided that sensors detect an inconsiderable curve and prevent a vehicle from cutting a curve and / or braking a vehicle in such a way that a possible evasive maneuver back into one's own lane is possible at any time without risk.

Alternatively, it can also be provided that the driver is warned by the driver assistance system or is made aware that the occurrence of oncoming traffic within the driver's visibility would result in an accident.

• 1 ein schematisches Blockschaltbild einer Ausführungsform der Erfindung;
• 2 ein schematisches Blockschaltbild einer Ausführungsform der Erfindung.

The present invention is explained in more detail below with reference to the exemplary embodiments given in the schematic figures of the drawings. It shows:

• 1 a schematic block diagram of an embodiment of the invention;
• 2nd a schematic block diagram of an embodiment of the invention.

1 shows a block diagram of a driver assistance method according to an embodiment of the invention. In the step S1 a section of the route ahead is determined, which the vehicle will drive in the immediate future.

In the step S2 a predictive wheel friction coefficient of a motor vehicle is estimated for the route section ahead. In the step S3 An allowable steering torque with which the vehicle can drive the route section ahead is estimated.

In the step S4 an actual steering torque of the vehicle is determined. In the step S5 a control command is determined and executed, which sets the permissible steering torque when it is determined that the actual steering torque deviates from the permissible steering torque.

2nd shows a block diagram of a driver assistance system according to an embodiment of the invention. The driver assistance system 10th includes a first interface 12th to means 14 to determine a section of the route ahead which the vehicle will drive in the immediate future.

It also includes a second interface 16 to means 18th for estimating a predictive wheel friction coefficient of the motor vehicle for the route section ahead. It also has a determination unit 20th to determine an actual steering torque of the vehicle. It also includes a computing unit 22 for estimating a permissible steering torque with which the vehicle can drive the section of the road ahead, and for determining a control command which sets the permissible steering torque.

Reference list

10th

Driver assistance system

12th

interface

14

Means for determining a section of the route ahead

16

interface

18th

Means for estimating a predictive wheel friction

20th

Investigative unit

22

Arithmetic unit

S1-S5

Procedural steps

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for better information for 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.

Patent literature cited

• DE 102012112725 A1 [0002]

Claims (11)

Method for operating a driver assistance system for vehicles, which has the following steps: - Determining (S1) a section of road ahead which the vehicle will be traveling in the immediate future; - Estimating (S2) a predictive wheel coefficient of friction of the motor vehicle for the preceding section of the route; - Estimating (S3) a permissible steering torque with which the vehicle can drive on the section of the road ahead; - determining (S4) an actual steering torque of the vehicle; - Determining and executing (S5) a control command which sets the permissible steering torque if it is determined that the actual steering torque deviates from the permissible steering torque. Method for operating a driver assistance system according to Claim 1 , whereby the predictive wheel friction coefficient is estimated using sensor data. Method for operating a driver assistance system according to one of the preceding claims, wherein the predictive wheel friction value is estimated using position data of the vehicle and known road data. Method for operating a driver assistance system according to one of the preceding claims, wherein the control command comprises a deceleration command and / or a steering command. Method for operating a driver assistance system according to Claim 4 , wherein wheels of the vehicle are selectively decelerated. Method for operating a driver assistance system according to one of the preceding claims, further determining whether the permissible steering torque can be set without initiating vehicle braking. Method for operating a driver assistance system according to Claim 6 , the vehicle being braked if it is determined that the permissible steering torque cannot be set at a current speed of the vehicle. Method for operating a driver assistance system according to one of the preceding claims, wherein further control commands are determined by a lane change assistant on the basis of the estimated permissible steering torque. Method for operating a driver assistance system according to one of the preceding claims, wherein the estimated predictive wheel friction value is checked for plausibility by means of a current or past wheel friction value. Method for operating a driver assistance system according to one of the preceding claims, it being determined whether an oncoming lane can be driven safely and the permissible steering torque being determined on the basis of this. Driver assistance system (10) for a vehicle with a first interface (12) to means (14) for determining a section of road ahead which the vehicle will drive in the immediate future, a second interface (16) to means (18) for estimating a predictive wheel friction value of the motor vehicle for the preceding section of the route, a determination unit (20) for determining an actual steering torque of the vehicle and with a computing unit (22) for estimating a permissible steering torque with which the vehicle can drive the section of road ahead, and for determining a control command which sets the permissible steering torque.

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