DE102013214401B4 - Method and device for operating a driver assistance system - Google Patents

Abstract

Method for operating a driver assistance system (1) for a motor vehicle by means of automatic steering interventions, with a target steering force (FSoll) being specified for implementation by the steering system (4), comprising the following steps:- specifying the automatic steering interventions by one or more Driver assistance functions (2); - providing a setpoint steering intervention to be set, in particular a setpoint steering force (FSoll) to be set, depending on the automatic steering interventions; characterized by:- checking whether the time profile of the target steering intervention to be set causes a critical excitation which is in the range of a natural frequency of the motor vehicle or a part of the motor vehicle, wherein if it is determined that the time profile of the adjusting target steering intervention a critical excitation is caused, one or more of the driver assistance functions (2) are deactivated or remain unconsidered when determining the target steering intervention to be provided.

Description

technical field

The present invention relates to a method and a device for operating a driver assistance system for a motor vehicle according to the preamble of claim 1 or claim 7. The invention also relates to a computer program product for carrying out such a method. In particular, the invention relates to motor vehicles with driver assistance functions that provide for a steering intervention. Furthermore, the present invention relates to measures for avoiding steering interventions that can impair the safety of the motor vehicle and the driver.

State of the art

Modern motor vehicles are often equipped with driver assistance functions that make steering grips. Driver assistance functions of this type are usually developed without corresponding standards and, due to a lack of quality requirements during development, can send faulty requests to the steering of a motor vehicle. This can endanger the motor vehicle and the driver, in particular when it is triggered by a steering intervention that is in the range of the natural frequency of the motor vehicle and can lead to oscillation.

Vehicle controllers, such as an ACC (Adaptive Cruise Control) system, automatically intervene in certain driving states by intervening in the steering in order to stabilize the motor vehicle or to support the driver. This generates a compensatory yaw moment that stabilizes the motor vehicle. In the event of a system error, there is a risk that the system will incorrectly evaluate the current driving status and generate an incorrect control intervention that impairs driving safety. In order to avoid false triggering, such driver assistance functions are designed with a safety concept that includes both a check of the hardware and the execution of the function. In particular, the steering intervention signals are checked for plausibility by a further safety function.

However, despite the correct functioning of the driver assistance functions, there may be automatic steering interventions which cause the motor vehicle to be excited in terms of frequency. If such a steering intervention takes place, the natural frequency of the motor vehicle is excited and oscillations can occur, which impairs the driving safety of the motor vehicle.

In particular, when several driver assistance functions are provided, each of which determines and requests its own steering intervention, the superimposition of steering interventions can lead to vehicle states that cannot be foreseen by one of the driver assistance functions. Previous systems only provide for correcting a swinging state of a motor vehicle using an ESP system when the motor vehicle is already in a swinging state.

From the pamphlet DE 10 2006 031 766 A1 a method for limiting a control intervention by a vehicle controller is known, in which a build-up gradient is determined for a control intervention by the vehicle controller and the control intervention is limited to a predetermined maximum value of the build-up gradient.

The pamphlet DE 10 2009 027 613 A1 discloses a method for operating a driver assistance system in which the driver assistance system can be switched off depending on a system event and the driver is informed in advance of an impending switch-off of the driver assistance system.

From the pamphlet DE 10 2005 049 083 A1 a vehicle dynamics control system is known in which steering torques or steering angles that do not yet have a safety-critical level are permitted during signal checks.

From the generic publication EP 1 478 561 B1 a method for controlling the driving stability of a vehicle is known in which, in the case of stable or unstable driving behavior, it is determined whether there is a tendency towards subsequent unstable driving behavior due to highly dynamic turning in, in which case the steering force and/or the steering angle of a steering handle is corrected in such a way that the steering force and/or the steering angle is modified depending on a map of a power steering (steering ratio) taking into account the speed of the vehicle and the map is adjusted towards a higher speed than the actual speed of the vehicle, so that when the steering handle is actuated, the driver is supported in the direction of an understeering vehicle course.

From the pamphlet DE 199 18 597 A1 a method for reducing the risk of motor vehicles tipping over is known, with the following work steps: constant determination of a tipping coefficient of the motor vehicle and comparison of the determined tipping coefficient with a predetermined limit value if the predetermined limit value is exceeded a steering intervention is automatically initiated; which increases with decreasing tipping stability and which is reduced or at least kept constant with increasing tipping stability.

It is the object of the present invention to provide a method for operating a driver assistance system in which safety-critical driving conditions, in particular driving conditions that can cause the motor vehicle to swing upwards, are avoided.

Disclosure of Invention

This object is achieved by the method for operating a driver assistance system for a motor vehicle according to claim 1 and by the device for operating a driver assistance system and the computer program product according to the independent claims.

Further advantageous developments of the present invention are specified in the dependent claims.

• - Vorgeben der automatischen Lenkeingriffe durch eine oder mehrere Fahrerassistenzfunktionen;
• - Bereitstellen eines zu stellenden Soll-Lenkeingriffs, insbesondere einer zu stellenden Soll-Lenkkraft, abhängig von den vorgegebenen automatischen Lenkeingriffen; und
• - Überprüfen, ob durch den zeitlichen Verlauf des zu stellenden Soll-Lenkeingriffs eine kritische Anregung bewirkt wird, die im Bereich einer Eigenfrequenz des Kraftfahrzeugs oder eines Teils des Kraftfahrzeugs liegt.

According to a first aspect, a method for operating a driver assistance system for a motor vehicle by means of automatic steering interventions is provided, with a target steering force being specified for implementation by the steering system, comprising the following steps:

• - Specification of the automatic steering interventions by one or more driver assistance functions;
• - Providing a target steering intervention to be provided, in particular a target steering force to be provided, depending on the predefined automatic steering interventions; and
• - Check whether a critical excitation is caused by the time course of the target steering intervention to be made, which is in the range of a natural frequency of the motor vehicle or a part of the motor vehicle.

If it is determined that a critical excitation is caused by the course over time of the target steering intervention to be provided, then one or more of the driver assistance functions can be deactivated or left unconsidered when determining the target steering intervention to be provided.

One idea of the above method is to monitor the steering force exerted on the steering of a motor vehicle due to automatic steering interventions in such a way that the resulting steering intervention or the gradient of the steering intervention cannot cause any excitation in the range of a frequency of the motor vehicle that is a natural frequency of the motor vehicle or a part of the motor vehicle. For this purpose, in addition to the steering intervention effected by the driver, the steering interventions carried out by the individual driver assistance functions are also taken into account, and with the aid of suitable signal processing, the force excitation range that could lead to the motor vehicle oscillating is monitored.

According to one embodiment, the critical excitation can be determined as a function of an excitation energy caused by the time course of the target steering intervention to be made in a specified frequency range, particularly if the excitation energy exceeds a specified first excitation threshold value.

Provision can be made for the predefined frequency range to depend on a speed of the motor vehicle and/or the level of the setpoint steering intervention and/or the gradient of the setpoint steering intervention.

If the excitation energy exceeds a predefined second excitation threshold value, which is smaller than the predefined first excitation threshold value, then the profile of the setpoint steering intervention can be suppressed or damped within the predefined frequency range.

• - eine DSR-Funktion;
• - eine HCA-Funktion;
• - eine AWA-Funktion; und
• - eine STA-Funktion.

The driver assistance functions may include one or more of the following functions:

• - a DSR function;
• - an HCA function;
• - an AWA function; and
• - an STA function.

It can be provided that the target steering intervention to be set is provided by applying the automatic steering intervention to a provided manual steering intervention, wherein the automatic steering intervention is applied to the manual steering intervention in particular by adding the steering torque of the manual steering intervention and the steering torques to be set of the one or more automatic Steering intervention is carried out.

• - eine oder mehrere Fahrerassistenzfunktionen, die jeweils ausgebildet sind, um einen automatischen Soll-Lenkeingriff zum Umsetzen durch das Lenksystem bereitzustellen;
• - einen Kombinationsblock, um abhängig von den durch die eine oder die mehreren Fahrerassistenzfunktionen bereitgestellten automatischen Lenkeingriffen einen Soll-Lenkeingriff vorzugeben; und
• - einen Überprüfungsblock, um zu überprüfen, ob durch den zeitlichen Verlauf der zu stellenden Soll-Lenkkraft eine kritische Anregung bewirkt wird, die im Bereich einer Eigenfrequenz des Kraftfahrzeugs oder eines Teils des Kraftfahrzeugs liegt.

According to a further aspect, a device for operating a driver assistance system for a motor vehicle through automatic steering interventions is provided. The device includes:

• - One or more driver assistance functions, each of which is designed to provide an automatic desired steering intervention for implementation by the steering system;
• - a combination block to specify a target steering intervention depending on the provided by the one or more driver assistance functions automatic steering intervention; and
• - A checking block to check whether a critical excitation is caused by the time profile of the target steering force to be set, which is in the range of a natural frequency of the motor vehicle or a part of the motor vehicle.

According to a further aspect, a computer program product is provided which is designed to carry out all the steps of the above method.

character list

• 1 eine schematische Darstellung eines Fahrerassistenzsystems mit mehreren Fahrerassistenzfunktionen; und
• 2 eine graphische Darstellung von Überwachungsgrenzen.

Preferred embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. Show it:

• 1 a schematic representation of a driver assistance system with several driver assistance functions; and
• 2 a graphical representation of monitoring limits.

Description of Embodiments

• - Eine DSR-Funktion 21 (DSR = Driver Steering Recommendation) ermittelt eine Lenkempfehlung, durch die ein erstes Lenkeingriffssignal LDSR bereitgestellt wird, das einem Fahrer des Kraftfahrzeugs durch einen Lenkimpuls, d. h. ein kurzzeitiges Lenkmoment, am Lenkrad mitteilt, in welche Richtung gelenkt werden muss, um das Kraftfahrzeug zu stabilisieren.
• - Eine HCA-Funktion 22 (Heading Control Assistant), die einem Spurhalteassistenten entspricht. Bei der HCA-Funktion 22 handelt es sich um ein kamerabasiertes System, das die Fahrspur mithilfe von Bildauswertefunktionen erkennt und das Kraftfahrzeug durch Lenkeingriffe automatisch in der Fahrspur hält. Die HCA-Funktion 22 stellt ein zweites Lenkeingriffssignal LHCA bereit.
• - Eine AWA-Funktion 23, die einem Ausweichassistenten entspricht. Die AWA-Funktion 23 erkennt eine drohende Kollision mittels einer geeigneten Annäherungserkennung, wie beispielsweise eines Kamerasystems oder mittels Distanzsensoren, und stellt ein drittes Lenkeingriffssignal LAWA zur Verfügung, das einen Lenkeingriff signalisiert, der zu einem Ausweichen bzw. zu einer Schadensminimierung bei einer drohenden Kollision führt.
• - Eine STA-Funktion 24, die einen Stau-Assistenten darstellt. Die STA-Funktion 24 ermöglich eine selbstständige Fahrt des Kraftfahrzeugs bei langsamem Verkehr bzw. bei Verkehrsstauungen, wobei das Kraftfahrzeug automatisch mit vorgegebenem Abstand hinter einem voraus fahrenden Kraftfahrzeug bewegt wird. Die STA-Funktion 24 stellt dazu ein viertes Lenkeingriffssignal LSTA zur Verfügung.

1 shows a schematic representation of a driver assistance system 1 with a number of driver assistance functions 2. The driver assistance functions 2 each cause an automatic steering intervention and can have one or more of the following functionalities:

• - A DSR function 21 (DSR = Driver Steering Recommendation) determines a steering recommendation, through which a first steering intervention signal LDSR is provided, which communicates to a driver of the motor vehicle through a steering impulse, ie a brief steering torque, on the steering wheel in which direction must be steered to stabilize the motor vehicle.
• - An HCA function 22 (Heading Control Assistant) which corresponds to a lane departure warning system. The HCA function 22 is a camera-based system that recognizes the lane using image evaluation functions and automatically keeps the motor vehicle in the lane by steering intervention. The HCA function 22 provides a second steering intervention signal LHCA.
• - An AWA function 23, which corresponds to an avoidance assistant. The AWA function 23 detects an imminent collision by means of a suitable approach detection, such as a camera system or by means of distance sensors, and provides a third steering intervention signal LAWA, which signals a steering intervention that leads to evasion or to minimizing damage in the event of an impending collision .
• - An STA function 24 representing a traffic jam assistant. The STA function 24 enables the motor vehicle to drive independently in slow traffic or in traffic jams, with the motor vehicle being moved automatically at a predetermined distance behind a motor vehicle driving in front. For this purpose, the STA function 24 provides a fourth steering intervention signal LSTA.

The first to fourth steering intervention signals LDSR, LHCA, LAWA, LSTA correspond to the steering torques to be set by the steering system 4 and are fed to a combination block 3 . Furthermore, the combination block 3 receives a manual _steering torque T steer (F _steer in 1 ) provided. From the first to fourth steering intervention signals LDSR, LHCA, LAWA, LSTA and the manual steering torque T _steering provided by the driver, a specification of a setpoint steering force F _{setpoint is} generated, in particular by summation, which is to be set in a steering system 4 .

For this purpose, the steering system 4 includes an actuator, in particular a steering motor, which engages with the steering shaft and applies a steering torque there, which causes a steering force equal to the target steering force F _target .

A monitoring block 5 is provided, to which the specification of the setpoint steering force F _setpoint is supplied. A filter unit 51 which filters the setpoint steering force F _setpoint can be provided in the monitoring block 5 . The filter unit 51 represents a bandpass filter, for example in the form of a Chebychev filter, which monitors a critical frequency range, for example between 1 Hz and 10 Hz, in particular between 1 Hz and 6 Hz. In particular, the frequency range can be varied as a function of a level of the setpoint steering force F _setpoint and/or as a function of a gradient of the setpoint steering force F _setpoint .

Signal components of the specification of the setpoint steering force F _setpoint at excitation frequencies within the range filtered by the filter unit 51 are supplied to a checking block 52, which can also be provided in the monitoring block 5. The checking block 52 checks the filtered specification of the desired steering force F _desired with regard to its excitation energy in the frequency range z extracted by the filtering. B. using a suitable signal evaluation. If it is determined that the Excitation energy has an energy value above a predetermined first excitation threshold value, an error reaction is triggered.

The error reaction can, for example, result in a complete switching off of all driver assistance functions 2 that cause an automatic steering intervention. This switching off can take place directly by intervention in the driver assistance functions 2 . Alternatively, the switching off can be performed using the combination block 3, which controls the application of the manual _steering torque T steer provided by the driver. In the combination block 3, for example, the cumulative application of the manual steering torque T _steering can be blocked.

Alternatively or additionally, the error reaction can contain a limitation of the force changes, ie the gradient of the setpoint steering force F _setpoint , to a predetermined value, such as a value between 10 kN/s and 30 kN/s, in particular to 20 kN/s. In particular, such an error reaction can precede the switching off of driver assistance functions 2, so that in the case of excitation energy with an energy value above a predetermined second excitation threshold value that is lower than the first excitation threshold value, the change in force is initially limited.

Alternatively, it can be provided that the frequency range filtered by the filter unit 51 is damped, so that the excitation energy in this frequency range is reduced to a non-critical level. For this purpose, it can be provided that the setpoint steering force F _setpoint is changed in such a way that the energy of the frequency components within the frequency range filtered by the filter unit 51 is reduced, while the energy of the profile of the setpoint steering force F _setpoint outside the filtered frequency range remains unchanged. This can be achieved by a suitable band stop filter, which filters out or more strongly damps the above frequency range from the signal of the specification of the setpoint steering force F _setpoint .

In one embodiment, the filter unit 51 can also carry out the bandpass filtering as a function of a speed specification G about the speed of the motor vehicle, since the oscillation behavior of the motor vehicle depends on the vehicle speed.

In 2 a diagram is shown as an example which, depending on the excitation frequency with the unit Hz, the size of the target steering force F _target with the unit N and the gradient of the target steering force F _target with the unit kN/s, shows the range in which the excitation energy , which can cause the motor vehicle to oscillate, exceeds a critical size. The degree that indicates the quantified danger of swinging open is indicated by the hatching of the area shown, with double hatching indicating an increased risk of swinging open than single hatching. The behavior shown in the diagram was determined empirically and can be used to define the area that is to be recognized by the monitoring block 5 .

Reference List

1

driver assistance system

2

driver assistance functions

21

DSR function

22

HCA function

23

AWA function

24

STA function

3

combination block

4

steering system

5

monitoring block

51

filter unit

52

verification block

Claims (8)

A method for operating a driver assistance system (1) for a motor vehicle by means of automatic steering interventions, a target steering force (F _setpoint ) being specified for implementation by the steering system (4), comprising the following steps: - specifying the automatic steering interventions by one or several driver assistance functions (2); - Providing a setpoint steering intervention to be provided, in particular a setpoint steering force (F _setpoint ) to be provided, depending on the automatic steering interventions; characterized by : - checking whether a critical excitation is caused by the time profile of the setpoint steering intervention to be made, which is in the range of a natural frequency of the motor vehicle or a part of the motor vehicle, wherein if it is determined that the time profile of the adjusting target steering intervention a critical excitation is caused, one or more of the driver assistance functions (2) are deactivated or remain unconsidered when determining the target steering intervention to be provided. procedure after claim 1 , characterized in that the critical excitation depends on an excitation energy, which is to be provided by the time course of the target steering intervention is effected in a predetermined frequency range, is determined, in particular when the excitation energy exceeds a predetermined first excitation threshold. procedure after claim 2 , characterized in that the predefined frequency range depends on a speed of the motor vehicle and/or the level of the target steering intervention and/or the gradient of the target steering intervention. Procedure according to one of claims 2 or 3 , characterized in that when the excitation energy exceeds a predetermined second excitation threshold value that is smaller than the predetermined first excitation threshold value, the course of the target steering intervention is suppressed or damped within the predetermined frequency range. Procedure according to one of Claims 1 until 4 , characterized in that the driver assistance functions (2) include one or more of the following functions: - a DSR function (21); - an HCA function (22); - an AWA function (23); and - an STA function (24). Procedure according to one of Claims 1 until 5 , characterized in that the setpoint steering intervention to be set is provided by applying the automatic steering interventions to a provided manual steering intervention, wherein the automatic steering interventions are applied to the manual steering intervention in particular by adding the steering torque of the manual steering intervention and the steering torques to be set of the one or more automatic steering intervention is carried out. Device for operating a driver assistance system (1) for a motor vehicle by means of automatic steering interventions, comprising: - one or more driver assistance functions (2), which are each designed to provide an automatic target steering intervention for implementation by the steering system (4); - a combination block (3) in order to specify a target steering intervention as a function of the automatic steering interventions provided by the one or more driver assistance functions (2); characterized by : - a monitoring block (5) to check whether the time course of the setpoint steering force (F _setpoint ) to be set causes a critical excitation which is in the range of a natural frequency of the motor vehicle or a part of the motor vehicle, wherein , if it is determined that a critical excitation is caused by the time profile of the target steering intervention to be provided, one or more of the driver assistance functions (2) are deactivated or are not taken into account when determining the target steering intervention to be provided. Computer program product containing a computer program which, when executed on a data processing device, implements the method according to one of Claims 1 until 6 performs.

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