WO2005087561A1

WO2005087561A1 - Method and system for identifying defective driving states of a vehicle in specific driving situations

Info

Publication number: WO2005087561A1
Application number: PCT/EP2005/051113
Authority: WO
Inventors: Andreas Köbe; Frank Schreiner
Original assignee: Continental Teves Ag & Co.Ohg
Priority date: 2004-03-16
Filing date: 2005-03-11
Publication date: 2005-09-22

Abstract

The invention relates to a method and a system for identifying driving states of a vehicle in specific driving situations, using an active and a passive safety system. The invention is characterised in that an aquaplaning state of the vehicle is determined and evaluated in correlation with a defective driving state of the vehicle. The driving state which is defective in terms of the aquaplaning state is determined on the basis of variables in the active safety system (10, 11, 12, 13).

Description

Method and system for recognizing faulty driving conditions of a vehicle in specific driving situations.

The invention relates to a method for recognizing faulty driving conditions of a vehicle in specific driving situations according to the preamble of claim 1

When driving a motor vehicle, the momentary adhesion with which a vehicle wheel rolls on the road is of great importance for driving safety. Not only for the transmission of the drive power and to ensure sufficient braking capacity, but also for any steering maneuvers and just rolling on e.g. it is important to ensure that the currently required adhesion is always guaranteed for safe control of all these circumstances. One aspect is that a vehicle wheel that has slipped due to a lack of frictional engagement can lead to disastrous consequences due to the then much lower sliding friction. It is therefore important for the operation of a vehicle to be informed, if possible before the transition to sliding friction, that the limit of the frictional connection between the wheel and the roadway has almost or completely been reached.

Aquaplaning is known to occur from a speed that can vary depending on the vehicle and tire characteristics. A film of water forms in particular under the front tire, causing the vehicle to

swims and loses contact with the road. The consequence of this is complete loss of vehicle control.

For the detection of aquaplaning e.g. Optical sensors are known with which the water level in front of the vehicle is estimated and the driver can be warned at an early stage. It is also known to use in security systems such as e.g. ESP or ASR, aquaplaning can be recognized by the wheel speeds. The automatic safety system detects the aquaplaning situation by evaluating the signals from the ABS speed sensors on the wheels. The detection that aquaplaning is present is described in patent DE 197 25 775 Cl.

Regardless of the warning of aquaplaning, the vehicle cannot be controlled by the driver or by automatic safety systems such as ABS or ESP. As long as the aquaplaning situation exists, the vehicle will continue to move at the speed that existed when the situation occurred. Steering or braking interventions by the driver or automatic systems such as ABS or ESP hardly influence vehicle behavior.

Measures to reduce safety-critical driving situations that occur during the aquaplaning situation, however, are not known.

The invention is therefore based on the object of providing a method and a system which prevent or at least reduce the effects of a safety-critical driving state which arises during aquaplaning. This object is achieved according to the invention by the features specified in claim 1 and in claim 6. Advantageous developments of the invention are specified in the subclaims.

The method for recognizing faulty driving conditions of a vehicle in specific driving situations with an active and a passive safety system advantageously provides that an aquaplaning state of the vehicle is determined and evaluated in correlation to a faulty driving state of the vehicle, the driving state which is faulty with regard to the aquaplaning state is determined on the basis of variables which are present in the active safety system.

The aquaplaning state of the vehicle is preferably determined using wheel speed sensors of the active safety system, as a result of which no additional sensors are required.

It is advantageous that the faulty Fahrzus ^~ FCAND based is determined from at least one size, the steering angular velocity, the steering angle, the model-based vehicle reference speed which Gierwinkelgeschwiniigkeit, the steering wheel angle, longitudinal acceleration, the F-ahrzeuggeschwin- speed, the brake pressure and / or the reproduce acceleration and / or their derivations or substitute signals. For the evaluation of the faulty state of the vehicle in connection with the aquaplaning state, preference is therefore only given to existing sizes, which simplifies retrofitting and reduces costs. It is advantageous that the size of the active safety system is compared with a threshold value that is dependent on the vehicle speed, and a passive and / or active safety system is controlled on the basis of the comparison result.

In addition, it is appropriate that the size of the active security system is its status (active / inactive).

The invention further provides a system for recognizing faulty driving conditions of a vehicle in specific driving situations, with an active and a passive safety system, which comprises an aquaplaning determining unit (20) for determining an aquaplaning state, an active safety device for determining driving states and an evaluation unit for evaluating the driving conditions as a function of the aquaplaning state is identified. i.

If the evaluation unit determines faulty driving conditions, active or passive safety systems are activated or modified.

Reversible measures of the passive safety system are preferably activated. These can be adjustments of the seats, backrests, headrests, belt tensioners can also be controlled or the windows and sunroof of the vehicle can be closed.

Irreversible measures are activated when an accident can be predicted safely. Only then can airbags be deployed or their deployment threshold modified. The essential idea of the invention is to provide an aquaplaning sensor system on the vehicle with which aquaplaning or the risk of aquaplaning can be detected, and in aquaplaning by using the sensors of the ABS, ASR, ESP and the like safety systems. evaluate a wrong driver reaction in relation to the aquaplaning situation and initiate safety-relevant measures.

None of the known active or passive safety systems is able to mitigate or reduce the effects of an aquaplaning accident at such an early stage. No additional hardware is advantageously required to identify the risk of an accident if an ESP control unit is present.

A critical driving condition of the vehicle arises at the end of aquaplaning when the tires roll off the road again. As a result, the kinematics of the vehicle are suddenly determined again by the position of the tires and the drive and braking torques.

If the driver during the aquaplaning situation drastic manipulations such as If the steering wheel has turned or the brakes are applied hard, the vehicle is caused to skid at the end of the aquaplaning situation due to the sudden wrong steering angle or the blocked tires.

The risk of an accident in aquaplaning is therefore considerably increased by incorrect actions by the driver. The actions can either be triggered by panic if the driver notices when the aquaplaning situation occurs, that he can no longer control the vehicle. Misconduct on the part of the driver can also be caused by the fact that he does not notice the existing aquaplaning situation or takes it too late in a steering intervention and therefore can no longer correct the intervention.

An embodiment of the invention is shown in the drawing and is described in more detail below.

In the drawing, a system is shown schematically, by means of which active or passive safety systems can be controlled automatically. The system has a driving dynamics control 10 with a control unit. Control devices generally include at least one of the control units ESP (electronic stability program), ASR (traction control), ABS (anti-lock control) and ARP (active rollover protection). At least one vehicle model is provided in the ESP control unit, which generates a vehicle course desired by the driver.

The ABS unit prevents the wheels from locking when braking, the ASR unit prevents the driven wheels from spinning, while the ARP unit tilts around the longitudinal axis and the ESP unit tends to rotate around the Vertical axis of a vehicle can be counteracted. The vehicle dynamics control 10 is connected to a detection system 11. Sensors for detecting the various dynamic vehicle parameters are of particular importance as actual value transmitters while the setpoints are being determined in the vehicle model, for example in the ESP control unit a reference yaw rate signal corresponding to a desired yaw angle movement of the vehicle. nal. The detection system 11 has one or more yaw rate sensors, which generates a yaw rate signal corresponding to a yaw angle movement of the vehicle; a lateral acceleration sensor which generates a lateral acceleration signal corresponding to a lateral acceleration of the vehicle; a steering angle sensor 12 which generates a steering angle signal corresponding to a steering angle; a plurality of wheel speed sensors 13, from which wheel speed signals are generated corresponding to each of the four wheel speeds; optionally a longitudinal acceleration sensor or a longitudinal acceleration model which generates a longitudinal acceleration signal corresponding to a longitudinal acceleration of the vehicle. In addition, at least one pressure sensor is provided in the brake system, which generates a brake pressure signal corresponding to the brake pressure of the brake system. The pressure sensor can also be replaced by a displacement sensor on the brake pedal.

The driving stability controls 10 currently in series use a multiple sensor (“sensor cluster”) for detecting vehicle rotation rate and lateral and possibly longitudinal acceleration. This sensor is arranged in the passenger compartment and communicates with the driving dynamics control 10 control unit via a CAN interface (WO 99/47889)

Other applications (e.g. ESP-2 or Active Front Steering AFS) provide that the signals from the sensor cluster are also used to actively influence the steering.

The system also provides an aquaplaning determination unit 20. This is connected to aquaplaning sensors 21 which can be designed as tire flap sensors or tire sidewall sensors, which are arranged in the casing or the sidewall of the tire and provide information about the current aquaplaning state. The aquaplaning sensor system can optionally also include HF sensors (radar) or optical sensors, which are arranged, for example, on the front of the vehicle and measure the height of the water film in front of the vehicle. The aquaplaning sensor system can also determine the aquaplaning situation from the information from the wheel speed sensors 13 of the active safety systems 10 by evaluating the coefficient of friction relationships already determined in the driving dynamics control 10 with regard to aquaplaning. In order to be able to determine in the aquaplaning determination unit 20 whether aquaplaning exists, the speed of the vehicle must also be taken into account. Since the speed of the vehicle is already calculated in the control units ABS and / or ESP, the information about the vehicle speed can be made available to the aquaplaning determination unit 20 by these units, which is to be symbolized in the drawing by the input 10. However, the aquaplaning determination unit 20 can also calculate the speed of the vehicle automatically. For this purpose, the rotary motion signals of the wheel speed sensors 13 are made available to it.

The system has an evaluation unit 30 which is connected to the aquaplaning determination unit 20 and the driving dynamics control 10. Since the vehicle dynamics control 10 receives the measured signals from the determination units 11 to 13, these can be forwarded directly or in processed form to the aquaplaning determination unit 20. Alternatively, the evaluation unit 20 is connected directly to the determination units 11 to 13 possible. In the evaluation unit 30, the aquaplaning state is set and evaluated in correlation to the sensor signals and / or the status of the driving dynamics control 10.

Based on the sensor signals and / or the status of the driving dynamics control 10, a driver behavior of the driver that is inappropriate for the aquaplaning situation can be determined. The unsuitable driving behavior of the driver is determined on the basis of the unsuitable driving state of the vehicle.

According to one embodiment, the automatic system detects a driver action that is inappropriate for the aquaplaning situation from sudden changes in the steering angle that lie above a speed-dependent threshold value. For this purpose, the system determines or receives the steering angle δ _α and / or the steering angle speed δ _r via the steering angle sensor 12 or from the driving dynamics control 10. The steering angle signal δ _{v / α} is compared in the evaluation unit 30 with a threshold value and as a function of the comparison result Example, a steering angle of the wheels of the vehicle that is inappropriate for the aquaplaning state is determined. The unsuitable driving reaction can be determined by comparing the actual movement path of the vehicle with the steering angle signal, for example using the signals from a longitudinal acceleration sensor or the yaw rate sensor to determine whether the vehicle is driving straight ahead with a large steering angle signal in the aquaplaning situation.

Instead of the steering angle or the steering angle speed, the driving state of the Vehicle can also be determined using the signals of the sensor cluster. From the reference yaw rate determined in the known driving dynamics model of the driving dynamics control 10 (more information on the formation of the reference yaw rate can be found in DE 195 15 051), which reproduces the curve path of the vehicle desired by the driver, to the driving state unsuitable for the aquaplaning situation of the vehicle are closed or the steering angle signal is checked for plausibility. It is also possible to conclude from the difference between the reference yaw rate and the measured yaw rate 11 that the vehicle is rotating and thus also in a driving state of the vehicle that is inappropriate in the aquaplaning situation.

In addition, the system detects the driver braking hard either via pressure sensors in the brake line or a displacement sensor in the brake pedal. Full braking can also be determined via the status of the driving dynamics control 10, for example the ABS control unit, and evaluated as an unsuitable driver action or unsuitable driving state of the vehicle.

Likewise, an ESP intervention situation is recognized on the basis of the status of the driving dynamics control 10, which results in braking intervention on at least the wheel on the outside of the curve.

The threshold values used to determine the unsuitable driving state of the vehicle are stored in a memory of the evaluation unit 30 as a function of the vehicle speed. The higher the vehicle speed, the smaller the turning angle of the vehicle wheels that deviates from the direction of travel of the vehicle, so that an improper driving state of the vehicle can be concluded. Depending on the nature of these tendencies in the evaluation unit 30, ie on the nature of the aquaplaning situation and the unsuitable driver reactions or the unsuitable driving state of the vehicle, a trigger signal is generated which causes the control unit 31 to actuate the active or preferably the passive ones Control safety systems because it is concluded that there is an increased risk of accidents. The actuation can consist of the actuators being actuated, for example a belt tensioner tightening the seat belt with a predetermined force and / or moving the seat into a predetermined position, or the actuators being prepared for actuation, for example by modifying the triggering thresholds eg be reduced.

In particular, the passive safety systems of the vehicle and its occupants are to be prepared for an accident. The hazard warning lights of the vehicle can also be switched on automatically via an additional switch in the control unit in order to warn other road users of an impending accident.

Passive safety systems of the vehicle such as Belt tensioners, extendable roll bars, backrest adjustment, etc. are brought into a position that is favorable for an accident.

In addition to activating the passive safety systems, the control unit 31 can generate a trigger signal for at least one active safety system 10 depending on the nature of these trends. The invention now uses the information about the driving dynamics of the active safety systems based on lateral acceleration, yaw rate, steering angle, vehicle speed (from rotational movement signals of the wheels) and the aquaplaning determination unit in order to make the unsuitable driver reactions or unsuitable driving states of the vehicle available to the active systems 10 (for example superimposed steering) in the aquaplaning situation. Based on the additional information, they can then make triggering decisions before a possible accident or adapt the triggering algorithms to the respective situation based on the detected critical driving situation in order to initiate measures in advance, for example to actively reset the steering angle independently of the driver. In this way, critical situations can be prevented or their effects weakened before they occur. The measures detected via the status of the driving dynamics control 10 can also be prevented if they do not produce a reaction due to the aquaplaning situation, that is to say if, for example, the ESP brake intervention would not lead to a reduction in the vehicle rotation about the vertical axis. The invention provides for the two systems to be combined in such a way that improved security functionality is available.

Claims

claims:

1. A method for recognizing faulty Fahrzxα a vehicle in specific driving situations, with an active and a passive safety system «characterized in that an aquaplaning state of the vehicle is determined and evaluated in correlation to a faulty driving state of the vehicle, the in relation to the Aquaplaning state faulty driving state is determined on the basis of variables that are present in the active safety system (10, 11, 12, 13).

2. The method according to claim 1, characterized in that the aquaplaning state of the vehicle is determined using wheel speed sensors (13) of the active safety system (10, 11, 12, 13).

3. The method according to claim 1 or 2, characterized in that the faulty driving state is determined on the basis of at least one variable which is the steering angle speed, the steering angle, the model-based vehicle reference speed, the yaw angle speed, the steering wheel angle, the longitudinal acceleration, the vehicle speed Brake pressure and / or the lateral acceleration and / or their derivatives or replacement signals is determined.

4. The method according to any one of claims 1 to 3, characterized in that the size of the active safety system with a dependent on the vehicle speed Threshold value is compared, and a passive and / or active safety system is controlled on the basis of the comparison result.

5. The method according to any one of claims ■ 1 to 4, characterized in that the size of the active security system is its status (active / inactive).

6. System for recognizing faulty driving conditions of a vehicle in specific ^■ driving situations, with an active and a passive safety system, characterized by an aquaplaning determination unit (20) for determining an aquaplaning state, an active safety device (10, 11, 12, 13 ) for determining driving conditions and an evaluation unit (30) for evaluating the driving conditions as a function of the aquaplaning state.

7. System according to claim 6, characterized in that an active (10, 11, 12, 13) or passive safety system is activated or modified in the event of faulty driving conditions.

8. System according to claim 6 or 7, characterized in that the passive safety system activates reversible measures.

9. System according to claim 6 or 7-, characterized in that the passive security system activates irreversible measures. ^• •