DE102012107186B4 - Method for detecting a dangerous situation of a vehicle based on at least one surroundings sensor and at least one inertial sensor - Google Patents

Abstract

Method for detecting a hazardous situation in a vehicle using at least one sensor, characterized in that the signal from the sensor is used to infer a side impact and at least one parameter for the controllability of the vehicle as a result of the side impact is determined, and that the driver's reaction to the impact is recorded and taken into account when assessing the controllability.

Description

The invention relates to a method for detecting a hazardous situation in a vehicle using at least one sensor according to the preamble of claim 1.

Inertial sensors, such as acceleration and yaw rate sensors, have been used for years to detect a dangerous situation in a vehicle in order to activate safety devices such as airbags, belt tensioners or the like in the event of a serious accident. In these classic hazardous situations, a serious accident is usually assumed and the triggering thresholds for the irreversible measures are correspondingly high.

In addition, environmental sensors such as radar or lidar sensors, but also camera systems, are increasingly being used in order to detect a dangerous situation in a vehicle as early as possible, possibly even an accident due to interventions in the longitudinal and lateral control of the vehicle, e.g. by braking and reduce or avoid steering. In addition, signals from surroundings sensors and inertial sensors can be combined with one another, used for mutual plausibility checks and adjustment of the algorithms, for example the triggering thresholds of occupant protection devices can be lowered if the surroundings sensors have already detected an impending collision.

The generic DE 10 2011 082 067 A1 describes a method for detecting a hazardous situation in a vehicle, with a forward-looking sensor system being used to determine a preliminary phase of a side impact of the vehicle. A hazard model of the motor vehicle is determined based on the signals from the anticipatory sensor system, and the ability of the motor vehicle to be controlled by a driver of the motor vehicle is determined based, for example, on a speed and/or a sideslip angle of the vehicle.

the DE 10 2008 043 637 A1 describes a method for detecting a side collision as a primary impact of a vehicle, a triggering decision for a protection system being made after a primary impact has been detected. In addition, after the primary impact has been detected, optical information is evaluated in order to determine a current situation surrounding the vehicle and/or a current driving condition of the vehicle, in particular if the vehicle has "gone out of control", with the current situation surrounding the vehicle and/or the current driving condition being used for detection an impending secondary impact are evaluated.

In the DE 10 2006 002 747 A1 describes a method for controlling personal protection devices in the event of a side impact, the personal protection devices being controlled as a function of a side impact sensor signal and a driving dynamics signal, and a lateral speed and/or a sideslip angle being used as the driving dynamics signal.

In real road traffic, however, hazardous situations also occur in which the primary event itself does not pose an immediate danger to the vehicle occupants, but as a result of which the driver may lose control of the vehicle.

The object of the present invention is therefore to recognize such a situation at an early stage. This object is solved by the features of the independent claims. Advantageous developments of the invention result from the dependent claims, with combinations and developments of individual features being conceivable.

An essential idea of the invention is that a side impact with an obstacle, i.e. contact with an obstacle on one side of the vehicle while driving in the direction of travel is not detected with conventional side impact algorithms, since in contrast to an object impacting the side of the vehicle, the Impact forces are significantly lower. However, due to the noise and vibrations, a side impact often leads to an incorrect or startled reaction on the part of the driver and a subsequently even more dangerous situation than the primary side impact itself. However, with appropriately aligned sensors, such a side impact can be detected and parameters for the remaining controllability or uncontrollability of the situation can be gained. Different sensors, some of which already exist in the vehicle, can be used for this.

Environment sensors make it possible to detect an imminent side impact at an early stage, for example by detecting the lateral distance, an expected impact angle and possibly other information about the environment, such as the course of the lane. The signal from the inertial sensor is compared with at least one predetermined threshold value for a side impact, and a side impact is concluded therefrom. In this case, this threshold value is smaller than the values usually provided for side impacts. In addition, a threshold value range characterized by a lower and an upper threshold value is preferably specified for a side impact, with the threshold value range in each case being below the threshold value that is usual for triggering occupant protection devices. Other sensors can also be taken into account.

If such a situation is recognized, parameters for controllability can also be determined.

If, for example, at least two acceleration sensors with sensitivity axes are arranged in a plane parallel to the roadway but at different angles to the direction of travel, the strength and direction of the momentum vector of the impact is determined from the signals from these sensors and the controllability of the vehicle as a result of the side impact is evaluated .

The steeper the impulse vector and the higher its strength, the less it is possible to control the vehicle after the impact and an impact turns into a classic primary impact, but there is also a counter-impulse on the vehicle and its occupants and thus you even with a correspondingly rigid crash barrier hardly controllable vehicle.

The angle of an imminent or actual contact between an obstacle and the longitudinal axis of the vehicle is also determined from the signal and the controllability of the vehicle as a result of the side impact is deduced from the size of the angle. Here, too, higher angles are to be classified as particularly critical.

In addition, the driver's reaction to the impact is preferably recorded and taken into account when assessing the controllability. If the driver reacts with moderate counter-steering and braking, the controllability is still high.

In addition, in a further preferred embodiment, the yaw rate or a variable derived therefrom is evaluated and/or the residual speed of the vehicle and/or the signals of the driving dynamics control system are evaluated.

The position of the vehicle in the lane or road and/or the distance to the edge of the lane or road or obstacles and/or the width of the road, the traffic situation or the available free space are also recorded and evaluated by environmental sensors, for example.

In addition, the duration of the collision is preferably recorded and evaluated. Guardrail crashes can last a few 100ms - much longer than standard crash crashes. A jump in yaw rate/steering angle or a reduction in longitudinal/transverse speed will probably be all the more difficult to control the shorter the period of time during which this occurs.

In addition, the reduction in speed during the side impact is recorded and evaluated, taking into account the influence of active braking intervention by the driver or an autonomous brake assistant. A strong reduction in speed, possibly coupled with a remaining high residual speed, leads to the vehicle becoming uncontrollable.

The invention will now be explained in more detail below using exemplary embodiments.

First, a method for detecting a side impact is presented, on the basis of which, for example, an assessment of the resulting controllability of the vehicle is then possible. A lateral impact is understood here as lateral contact at an acute angle with a stationary or moving object. Obtuse angles usually lead to a high crash severity or a significant reduction in speed and are already recognized by existing crash detection systems from passive safety.

A stationary object is primarily a lane boundary, i.e. a crash barrier/guard rail or wall made of metal or concrete. A moving object is primarily another vehicle in oncoming traffic (car, truck). A side impact with a moving object is usually caused by a lane change when the driver overlooks the object in the next lane or the vehicle and object change lanes from two different sides at the same time into the same lane.

This impact differs significantly from classic front or side crash events and has not yet been taken into account by their algorithms.

With the method presented, such an accident type is to be detected, for example, in a second step, then an assessment of the resulting controllability of the vehicle and / or the driving situation immediately after carry out an impact. With this detection and depending on the situation assessment, activation or adaptation of active safety systems (e.g

lane keeping, automatic braking, stability functions (ESC)) and/or passive occupant protection systems (e.g. electric belt tensioners, side airbags) with the aim of increasing the controllability of the driving situation and/or protecting the occupants. In addition, functions for warning/information about the surroundings can also take place, such as activation of hazard warning lights, horn, sending an eCall.

The accident type is identified and the vehicle's ability to be controlled and/or the driving situation is assessed during or immediately after the side impact, based on crash, chassis, position determination and/or environment sensor information or their (model-based) fusion . The status information of a driving dynamics control system (e.g. ESP control intervention) can also be used for the evaluation.

Front radar, side/rear radar, front camera (mono/stereo), reversing camera, top view cameras, lidar as well as ultrasonic sensors or a combination thereof come into consideration as environment sensors.

Classic crash sensors or vehicle dynamics sensors can be used for the inertial sensors.

The crash sensor system consists, for example, of high-g acceleration sensors, implemented centrally or as satellites, high-g yaw rate sensors, pressure sensors and/or structure-borne noise sensors (CISS).

For driving dynamics and chassis control, the low-g inertial sensors (acceleration, yaw rates, up to 6 axes), wheel speed sensors, steering angle and pedal actuation, for example sensors for pedal travel sensors, brake light switches or pressure sensors, are often also available and can be taken into account here , THZ or the like are present.

In addition, signals from the position determination can preferably also be taken into account, such as by global satellite navigation systems (GPS, Galileo...), possibly even improved by signals from the inertial sensor system and information about the environment, such as digital map and lane information.

To detect/classify the side impact, the following information is evaluated or calculated in part or in combination.

On the one hand, a geometric angle of impact on the obstacle, for example the crash barrier, is determined by means of environment sensors, this being camera-based, for example, and these environment sensors are also used to detect the development around the edges and the lane markings, and this information is also taken into account, or front radar and/or side radar are used.

In addition, in the preferred embodiment, the momentum vector (vx,vy) of the impact on the crash barrier is calculated, e.g. from crash sensors (e.g. high-g: vx - INT{ax}) and chassis sensors (low-g; yaw rates), and compared with at least one predefined threshold value for a side impact and, given a correspondingly small/flat angle, a side impact is concluded.

For example, contact is also recognized and the crash severity is determined on the basis of CISS; Acceleration and/or pressure lateral satellites: or a low-g inertial sensor system.

In addition, in a preferred embodiment, the reduction in speed during contact with the crash barrier is determined, e.g. by integrating acceleration sensor signals and/or evaluating wheel speed sensor information before/after the impact, which cannot be attributed to (driver-triggered or automated) braking interventions.

The duration of contact with the crash barrier is also evaluated, e.g. based on vibration detected via low-g inertial sensors and/or environment sensors such as side radar, side ultrasound, camera or radar signals and/or steering angle of the vehicle and/or position determination.

Vertical vibrations, e.g. in the case of a verge or green strip in front of the crash barrier, can also be detected using spring deflection sensors and/or low-g inertial sensors (z-direction).

Lane departure detection is also carried out via a camera or satellite-supported position detection.

Depending on the type of sensor, detection takes place before, during and/or after the impact.

For example, a test vehicle for detecting a side impact was equipped with a camera for lane detection, a side radar and side satellites for measuring pressure and/or acceleration, with the evaluation of low deflections already taking place here, possibly using the raw signals without a filter.

In addition, a standard ESC sensor system was used as an inertial sensor system with detection of lateral acceleration and yaw rate, and the steering angle sensor and wheel speed sensors were also evaluated.

If the camera detects a lane departure or lane change and the side radar detects a lateral object, whether stationary or moving and an approach to this, the time-to-collision and preferably the probability of the impact are calculated, for example based on hypotheses, e.g. crash 100% if physically unavoidable despite cooperative action of vehicle and object.

If side satellites now show small deflections (p and/or g) and preferably within a narrow time window, the low-g ESC inertial sensors show deflections for lateral acceleration and/or yaw rate, then there is an impact.

Immediately after the suspected impact, one or more sudden steering actions by the driver are detected (major steering wheel angle changes). A jump in the direction of travel in relation to the lanes is confirmed by the lane detection of the camera. Lane departure may be detected.

A measure of the reliability of detecting the side impact is determined on the basis of the signals. Based on the respective quality of the merged sensor signals, a measure is formed that represents the quality of the detection of the side impact. With the information on the recognition quality, various intervention levels can then be activated (e.g. slight automatic braking with low recognition quality, automatic full braking with very high recognition quality). This is relevant with regard to false tripping and functional safety.

A speed threshold for the driver's own vehicle, which must be exceeded before the collision, serves as a further supplement. In this way, the detection of the side impact, which is purely based on passive crash sensors, can be made more sensitive without certain misuse/no-fire cases that only occur at low speeds (curb, 30 km/h) leading to an incorrect detection.

Such a speed threshold can also be helpful for excluding false detections at low speeds for fusion approaches that are not only based on purely passive crash sensors.

• Zunächst ist der Anprall selbst natürlich ein Ereignis, welches zu einer gewissen Reduzierung der Kontrollierbarkeit führt und aus seitlich gerichtetem Radar (SRR), Frontradar und/oder Mono oder Stereokamera oder einer seitlich gerichteten Kamera oder Rund-Um-Kamerasystem (Top View) erkennbar ist.

To assess the controllability before, during and after the side impact, the following information, for example, is evaluated/calculated partially or in combination:

• First of all, the impact itself is of course an event which leads to a certain reduction in controllability and is detectable from side-facing radar (SRR), front-facing radar and/or mono or stereo camera or a side-facing camera or all-round camera system (top view). .

As already explained at the beginning, the impulse vector (vx,vy) of the impact on the crash barrier is calculated, for example, from crash sensors (e.g. high-g) and chassis sensors (low-g; yaw rates). The larger this momentum vector, the more difficult it is for the driver to control the traffic situation.

Another parameter or criterion is the geometric impact angle on the crash barrier. It is detected, for example, by means of environment sensors (front radar and/or stereo camera, side radar (SRR) detection of roadside development; detection of roadway markings or roadside development by monocamera). Controllability: The larger this angle, the more difficult it is for the driver to control the traffic situation.

A driver condition assessment is based on the driver's reaction, e.g. whether he is passive or active, i.e. braking, steering and trying to intercept the vehicle and how moderate this reaction is. Large hectic reactions, especially on the steering (most common error: jerking the steering wheel) are to be classified as critical as well as complete passivity.

Occurring yaw moments or a jump in the yaw angle enable the “heading angle” to be estimated, i.e. the direction of travel after contact with the crash barrier. These variables can be obtained from the crash and chassis sensors. A large change in the direction of travel is usually not manageable for a normal driver.

A critical parameter can also be obtained by detecting lane departure after an impact, e.g. using a camera with lane recognition and/or satellite-based navigation, possibly in conjunction with the evaluation of driving dynamics sensors - leaving the lane indicates less controllability.

In addition, the remaining vehicle speed is preferably evaluated after the impact with the crash barrier, which is detected, for example, via CAN from the engine control unit or the wheel speed sensors. The higher the residual speed, the more difficult it is to control.

In addition, the reduction in speed can be determined via the impact of the crash barrier, for example calculated from the initial vehicle speed before the impact and the residual vehicle speed or by integrating the acceleration information

The status of the driving dynamics control system after the collision with the crash barrier is also a preferred parameter and can be determined from the control unit(s) for ESC and ABS. Interventions by the systems in the driving dynamics are indicators of a critical situation in which controllability is potentially reduced. If these systems determine that signals are implausible (e.g. different wheel speeds) after the impact, there is also a potentially critical situation with reduced controllability.

The status of other chassis systems after the impact with the crash barrier, such as the steering, vertical dynamics control or damper control, also offers signals for controllability - if the above-mentioned systems determine the implausibility of signals (e.g. different wheel speeds) after the impact, there is a potentially critical situation with reduced controllability.

The number of lanes or total lane width also offers a parameter. Detected either via a camera system or using GPS position and map material, the following applies to controllability: the narrower the lane width, the less space for stabilizing driving manoeuvres.

In addition, the current traffic situation overall, i.e. also based on following/neighboring vehicles, the remaining free space, safety distance between each other in the direction of travel and perpendicular to the direction of travel can be taken into account and the traffic situation can possibly even be evaluated from the history or based on environmental sensor measurements before or after a Period of time. The more space and time the driver has to intercept the vehicle, i.e. the later a second impact threatens, the lower the criticality

Each of the parameters mentioned above enables an assessment on its own, but a summary of a plurality of such parameters forms an overall picture and a plurality of parameters are preferably recorded and an overall value for the controllability is derived from the respective degree of controllability and the reactions are based on this overall value customized.

If the level falls below a predetermined level of controllability, at least individual protective measures are activated, with different measures depending on the type of parameter detected and/or the severity.

Automatic braking is preferably initiated, which can be adapted depending on the driver's behavior and the hazardous situation in terms of intensity and withdrawal of the intervention.

The direction of travel can be stabilized by applying the brakes to individual wheels. Or the control thresholds of an ESC system are adjusted in order to achieve such stabilization.

In addition, particularly in the event of a panic steering reaction, the steering movement is dampened or directed in a predetermined direction by counter-torques.

For this purpose, the course of the direction of the lateral obstacle, in particular a crash barrier, is preferably detected and lane guidance parallel to the course of the direction of the lateral obstacle is supported by wheel-specific braking interventions and/or steering interventions.

In addition, the damper characteristics of an adaptive chassis damping of the vehicle are preferably adapted, in particular the damping is increased in order to reduce wheel load fluctuations. In addition, the triggering thresholds of reversible and/or irreversible occupant protection systems can be adjusted, in particular reduced, in order to ensure early triggering in the event of a secondary accident.

Claims (12)

Method for detecting a hazardous situation in a vehicle using at least one sensor, characterized in that the signal from the sensor is used to infer a side impact and at least one parameter for the controllability of the vehicle as a result of the side impact is determined, and that the driver's reaction to the impact is recorded and taken into account when assessing the controllability. procedure after claim 1 , characterized in that at least two acceleration sensors with sensitivity axes are arranged in a plane parallel to the roadway but at different angles to the direction of travel and the strength and direction of the impulse vector of the impact is determined from the signals of these sensors and the controllable capability of the vehicle as a result of the side impact is assessed. Method according to one of the preceding claims, characterized in that the angle of an imminent or actual contact between an obstacle and the longitudinal axis of the vehicle is determined from the signal and the controllability of the vehicle as a result of the side impact is inferred from the magnitude of the angle. Method according to one of the preceding claims, characterized in that the yaw rate or a variable derived therefrom is evaluated. Method according to one of the preceding claims, characterized in that the residual speed of the vehicle after the impact is evaluated. Method according to one of the preceding claims, characterized in that the signals from the vehicle dynamics control system are evaluated. Method according to one of the preceding claims, characterized in that the position of the vehicle in the lane or road and/or the distance from the edge of the lane or road or obstacles and/or the width of the road is recorded and evaluated. Method according to one of the preceding claims, characterized in that the traffic situation and the available free space are recorded and evaluated by environment sensors. Method according to one of the preceding claims, characterized in that vibrations of the vehicle are detected and evaluated in the direction of its vertical axis. Method according to one of the preceding claims, characterized in that the duration of the collision is recorded and evaluated. Method according to one of the preceding claims, characterized in that the reduction in speed during the side impact is recorded and evaluated, the influence of an active braking intervention by the driver or an autonomous brake assistant being taken into account. Method according to one of the preceding claims, characterized in that a plurality of parameters are recorded and an overall value for the controllability is derived from the respective degree of controllability and the reactions are adapted on the basis of this overall value.