DE10361281A1 - Method for detecting critical driving situations of a vehicle - Google Patents

Abstract

The The invention relates to a method for detecting critical driving situations a vehicle, in particular for detecting an impending vehicle rollover, in the driving situation dependent movement quantities of Vehicle measured at least two places, by far each other on one side of a normally horizontal Are the axis of rotation of the vehicle, from the measured quantities of motion and the distance of the locations of the measurements, a rotation angle and a rotational angular velocity of the vehicle This normally horizontal axis of rotation can be calculated and the calculated values for Angle of rotation and angular velocity as a function of vehicle-specific Thresholds are evaluated to control signals for driving of safety systems in the vehicle to produce and output.

Description

The The invention relates to a method for detecting critical driving situations a vehicle, in particular for detecting an impending vehicle rollover.

In Today's motor vehicles incorporate a variety of monitoring and control systems, which intervene in the chassis and the braking system as well as reversible and irreversible occupant protection devices and systems to control the Driving safety and driving comfort to increase or to the occupants of a Vehicle in case of dangerous Impact or a rollover preferably to protect.

Next usual Brake control systems that lock the vehicle wheels In particular, prevent an emergency or panic braking Vehicle dynamics systems known as either the brake control systems for Influencing the longitudinal and transverse dynamics of the vehicle, or designed as a chassis control systems are used as Komforsysteme to improve ride comfort in the Engage suspension.

From the DE 196 09 176 A1 For example, there is known a method of detecting a vehicle rollover that serves to deploy occupant protection devices, such as roll bars, belt tensioners, front and side airbags.

to Detecting a vehicle rollover in the vehicle longitudinal direction, Vehicle transverse direction and in the vehicle vertical direction to the vehicle recorded accelerations with corresponding acceleration sensors, to calculate an acceleration vector. Furthermore, a rotation rate sensor provided, the angular velocity of the vehicle with respect to its longitudinal or Roll axis recorded. You may also have a second Rotation rate sensor can be provided for the angular velocity of the vehicle its transverse or pitch axis measures. The acceleration vector becomes dependent on from the detected roll and optionally pitching speed with Thresholds compared to a decision on an upcoming vehicle rollover hold true.

From the DE 100 25 259 C2 A tripping algorithm is known which processes the sensor signal of a yaw rate sensor provided in a safety system of a motor vehicle to make a triggering decision to trigger at least one occupant protection or safety device of a safety system. The triggering algorithm processes, in addition to the output signal of the rotation rate sensor for making a triggering decision, the output signal of an acceleration sensor which detects the acceleration acting on the vehicle in the vertical direction and an output signal of a tilt sensor. In addition to or instead of the inclination sensor may also be provided a lateral acceleration detecting acceleration sensor.

From the DE 100 05 010 C2 a reversible belt tensioner is known, which is already in the run-up to a possible accident, so when a critical driving situation is detected, operated to bring vehicle occupants before a dangerous impact or rollover in a position in which a comparatively low Verletzunsrisiko exists.

to In addition to the movements of the vehicle occupants, for example, by image processing or by means of a Gurtauszug-determining means are detected, including the vehicle speed, the steering angle, the yaw angle, the yaw rate, etc., to over an operation to decide the reversible belt tensioner.

From the DE 101 21 386 C1 Further, a method for driving a reversible occupant protection means in a motor vehicle is known in which the steering angle, the wheel speeds, the yaw rate and the lateral acceleration are measured in a vehicle to close an incipient spin as a result of oversteer or understeer. Furthermore, with the aid of a brake light switch and an output signal of a brake assist system, which indicates that this system is active, an emergency braking can be concluded, so that the various reversible occupant protection means, such as belt tensioner, seat adjustment and seat displacement and the like can be activated.

to Control of the various occupant protection systems need the known methods respectively corresponding sensors to provide the necessary information about the to get each driving situation. Especially for the detection of rollovers are special yaw rate sensors required.

The as well as airbag systems, anti-lock and / or anti-skid brake control systems, as well as vehicle dynamics and suspension control systems essentially isolated solutions between which an information exchange does not or at best limited takes place.

From that The invention is based on the object, a method the type mentioned in the introduction so that it does not have its own specific Sensors, in particular without special sensors for detecting the Danger of a vehicle rollover does not require corresponding safety systems, e.g. Occupant protection systems or driving safety systems (active steering, braking or suspension systems) head for.

These The object is achieved by the method according to claim 1. advantageous Further developments and refinements of the invention are described in the subclaims.

According to the invention is thus in a method for detecting critical driving situations of a vehicle provided that driving situation dependent movement quantities of Vehicle measured at least two places, by far each other on one side of a normally horizontal Rotary axis of the vehicle are; that from the measured quantities of motion and the distance of the locations of the measurements, a rotation angle, e.g. a roll and / or pitch angle, and a rotational angular velocity, e.g. a Roll and / or pitch rate of the vehicle with respect to this normally horizontal axis of rotation can be calculated; and that the calculated Values for Angle of rotation and angular velocity as a function of vehicle-specific Thresholds are evaluated to control signals for driving of safety systems in the vehicle to produce and output.

By the method according to the present Invention can be critical driving conditions, especially under utilization the acquisition of driving situation-dependent movement variables for others Vehicle systems, detect, so no own measurements required for this are. If necessary, you can therefore otherwise existing rotation angle and / or rotational angular velocity sensors saved become.

Conveniently, are considered as driving situation-dependent Motion quantities accelerations, especially accelerations acting on the vehicle body, which act on the vehicle in its vertical direction.

One Procedure is that from the measured accelerations first the rotational angular velocity is determined to be subsequent to this to determine the angle of rotation, wherein the calculation of angular velocity and rotation angle by integration or by state observation done using Kalman filters.

There it in static, quasi-stationary and stationary states of the vehicle is difficult or nearly impossible from the relative low values for the roll or pitch rate, so for the angular velocity about the vehicle longitudinal or about the vehicle transverse axis reliable Values for To obtain the roll or pitch angle is at a preferred embodiment the invention provides that from the measured accelerations an absolute vehicle inclination or rotation angle under consideration the gravitational acceleration is calculated by means of trigonometric relations.

According to one Another embodiment of the present invention are as driving situation-dependent motion variables spring travel in the field of vehicle wheels measured.

One Method is that the rotational speed of the vehicle around its longitudinal and / or transverse axis by derivation of the spring travel after the time below adequately replicate the distances the corresponding locations is determined at which the spring travel measured were calculated from the continuously determined values for the rotational speeds the vehicle whose rotation angle can be determined.

alternative or additionally it is also possible that for the spring reasons a relative vehicle inclination or rotation angle is calculated.

A particularly advantageous embodiment of the invention is characterized by assuming that the values for Angle of rotation and angular velocity in different ways be determined, and that for plausibility of the values for rotation angle and Rotational angular velocity takes into account all determined values become. This allows very early critical values for Roll and / or pitch angle also for Roll rate and / or pitch rate can be verified so that despite early activation from security systems early Hedging and thus very low false triggering rate is obtained.

A different possibility an improved early detection To receive critical driving situations is that in the Evaluation of the calculated values for angle of rotation and angular velocity the driving dynamics descriptive quantities, such as vehicle lateral acceleration, Yaw rate, float angle velocity, vehicle speed and the like become.

The Invention will be described below, for example, with reference to the drawing explained in more detail. In show this:

1 a simplified schematic plan view of a motor vehicle to illustrate installation locations for sensors for detecting driving situation-dependent movement variables; and

2 a schematic block diagram illustrating a system according to the invention for controlling security systems.

As in 1 is shown, are mounted in a motor vehicle, a plurality of sensors in a typical arrangement to detect different driving situation-dependent movement quantities. In particular, there are speed sensors Sdrz on all four vehicle wheels whose output signals drz_vr, drz_vl, drz_hr and drz_hl correspond to the rotational speed of the vehicle wheels front right, front left, rear right and rear left. These signals are used together with one of the yaw rate Ωz of a centrally arranged yaw rate sensor SΩ and a signal ay_esp for lateral acceleration of a centrally located lateral acceleration sensor Say for the evaluation and active control of driving safety and driving dynamics. Furthermore, spring travel sensors Sfw are arranged on all four wheels, which supply the suspension travel with the arrival and rebound of the wheels corresponding signals fw_vr, fw_vl, fw_hr, fw_hl. Furthermore, acceleration sensors Saz are provided on the left and right front wheels and on the right rear wheel, which provide acceleration signals az_vr, az_vl, az_hr for the body acceleration at these locations. Other arrangements are also conceivable. The suspension travel and body accelerations are used, for example, to control the chassis in order to improve ride comfort and driving safety.

to Activation of occupant protection systems in case of dangerous Driving situation and / or an accident with rollover and / or dangerous Impacts are still acting in vehicle longitudinal and transverse direction accelerations ax_ab, ay_ab and with a corresponding roll rate sensor the Roll rate Ωx detected.

In the embodiment according to 2 Be the outputs of the individual sensors S via an interface 10 to a roll and pitch calculation unit 11 created. The interface works according to the so-called "plug and play method", ie the interface 10 detects which sensors 5 are actually present and connected in the vehicle and configures the appropriate monitoring and control algorithms to control the individual active and passive guards, such as airbags, seatbelt pretensioners, brakes, etc.

The roll and pitch calculation unit 11 provides the roll rate Ωx and the pitch rate Ωy corresponding signals to a rollover detection unit 12 to a recognition unit 13 hazardous driving situations and in a manner not shown, where appropriate, to other driving safety, driving dynamics and driving comfort influencing facilities.

If a rollover due to impermissibly high rolling and / or pitch rates Ωx, Ωy detected, so is the control 14 for the protection systems a roll bar and / or belt tensioner and possibly also activates the airbags.

Correspondingly, when detecting dangerous driving situations, reversible occupant protection systems such as belt tensioners and seat adjusters are due to a corresponding output signal of the recognition unit 13 for detecting dangerous driving situations from the control 14 activated for protection systems. Also, ESP interventions can be better tuned, for example by more precise statements about the wheel load distribution.

at Detection of impending rollover or dangerous Driving situation can active driving safety systems are activated (braking, steering intervention or chassis intervention).

According to the invention for calculating roll and pitch angles as well as roll and pitch rates that of the body acceleration sensors Saz and / or spring travel sensors Sfw supplied signals for the different body accelerations az and the different ones Spring travel fw supplied signals used.

The rolling angle φ is calculated from the vehicle body acceleration az via the double integral via the roll angular acceleration φ "= (φ ² p / dt ² ), ie via the angular acceleration relative to the vehicle longitudinal axis Ax.

The roll angle acceleration φ "in turn results from the difference between the body acceleration az_ and az_r on the left and right sides of the vehicle and the distance of the sensors Saz according to the following equation: φ '' = (az_vl-az_vr) / distance sensors

The Integrals can be calculated in time-discriminated.

By multiplying the individual roll angular acceleration values by the time T_sample between two detection times, the roll rate φ '= (dφ / dt) or the roll rate Ωx can be determined. By multiplying again with the time T_sample between two sampling and measured value detection times, the roll angle then results at time t _{N + 1} . according to the following equations: φ'_N + 1 = φ '' _ N + 1 ∙ T_sample + φ'_x φ_N + 1 = φ'_N + 1 ∙ T_sample + φ_x

This applies to dynamic processes φ_x = φ_N φ'_x = φ'_N while in stationary operations φ_x = φ_stat φ'_x = (φ_stat (N) - φ_stat (N-1)) / T_sample applies.

The calculation of φ_stat takes place in the static case or else in the quasi stationary case by simple trigonometric relations according to the following equation: cos (φ_stat) = (g - az_measured) / g where g represents the gravitational acceleration. This takes into account in particular that the acceleration sensors Saz for detecting the body acceleration in the direction of the vertical axis of the vehicle, ie in the z-direction are designed so that their output value is zero, ie az = 0, when the vehicle is on egg ner horizontal plane and no further accelerations are acting on it except the gravitational acceleration.

is however, the vehicle is inclined to the horizontal, e.g. on a bevel Lane, so no longer affects the full acceleration of gravity in the detection direction of the acceleration sensor Saz, so that this an output signal delivers that increases with increasing pitch or roll angle the gravitational acceleration perpendicular to its detection direction the acceleration setup sensor acts. With the help of the body acceleration detecting Acceleration setup sensors, it is thus possible, an absolute vehicle tilt angle in both roll and pitch direction, so one Vehicle tilt angle relative to the direction of gravitational acceleration.

In can advantageously stationary operations be defined and detected, since the gravitational acceleration in the Sensors is mitgemessen.

The Calculation of φ_stat can also be used in the dynamic case every measuring or sampling time can be made in the same way as in the static case. By comparing φ_stat (N) with φ_N, one can then plausibility check the determination of the roll angle φ.

The solution the above equations for the calculation of roll angle φ and roll rate φ 'or Ωx is performed via the Integration or by means of so-called state observers, such as Kalman filters or the like.

The measurement and calculation of the pitch angle and the pitch angle rate Ωy and their plausibility is carried out in a corresponding manner, for example, that instead of the output signals of the left and right front body acceleration sensors Saz_vl, Saz_vr of Ausführungsbeipiels in 1 the output signals of a front and a rear Aufbeschleunigungssensors Saz_vr or Saz_hr are used so that the angular acceleration is determined by the vehicle transverse or pitch axis Ay for further calculations.

So long the vehicle with all four wheels Ground touched, it is also possible relative roll and pitch angles from the spring paths fw_vr fw_vl, fw_hr and fw_hl and from the mutual distances of the corresponding spring travel sensors Sfw to calculate. It is also possible that both for pitch angle as well as for Roll angle respectively a right and a left pitch angle value or a front and a rear roll angle value can be determined.

in this connection is therefore to be considered that from the Federwegwerten only relative roll or tilt angle can be determined while absolute roll or pitch angles from the body acceleration especially for a stationary vehicle can be determined.

Around from the determined values for Roll and pitch angle as well as from roll and pitch angle rate possible early on a dangerous Driving situation, in particular to close an impending rollover, can be for the Evaluation of the determined values also include the system dynamics.

For example let yourself so distinguish whether a vehicle occupies a certain angle, because it drives on one side a ramp or a banked curve.

in the the former case has to be taken into account that here the vehicle already at high vehicle speeds due to the ramp approach tilts while stationary or quasi-stationary case, So at very slow speeds only tilts when the absolute inclination of the vehicle exceeds a critical value.

At the Driving a steep curve are high vehicle speeds the Prerequisite for a Safe driving, as low vehicle speeds to the accident to lead.

Further can also be determined from the measured spring travel and calculated travel speeds be distinguished whether an inclination of the vehicle by a Dumping on one side, for example because of a right-sided Embankment or by taking off on the other side, for example due to a Left-sided ramp or a right-sided hacking at high Float angle is present.

Out the individual accelerations measured in the area of the vehicle wheels az acting in the vertical direction of the vehicle on the construction, and the spring travel fw at the individual wheels can thus not only by Nodding and wavering are detected, but also additional information about that where and in which direction forces act on the vehicle and whether this is a dangerous Driving situation is caused, which may lead to a rollover to lead can.

By the calculation of pitch and roll behavior both from the body acceleration az and the spring travel fw results in a more reliable and thus earlier detection in particular an impending rollover, so for example a corresponding rollover sensor to activate a roll bar omitted can. The assessment of roll and pitch behavior due to different Measurements makes the detection of a rollover more plausible and thus makes it possible an early one and timely deployment of occupant protection systems such as airbags, Belt tensioners, seat adjustments and the like.

One Advantage of the invention over A roll or a pitch rate sensor also consists in that the roll axis and the pitch axis detected in their course in the vehicle can be what about the rollover detection (Rollover) is important. A roll rate sensor does not detect where the Roll axis in the vehicle runs.

Claims (12)

Method for detecting critical driving situations of a vehicle, in which - driving-situation-dependent movement quantities (az_r, az_l; az_v, az_h; fw_vr, fw_vl; fw_hr, fw_hl; fw_vr, fw_hr; fw_vl, fw_hl) of the vehicle are measured at at least two locations which are at a distance (d) each lie on one side of a normally horizontal axis of rotation (A _x ; A _y ) of the vehicle, - from the measured quantities of motion (az_r, az_l; az_v, az_h; fw_vr, fw_vl; fw_hr, fw_hl; fw_vr, fw_hr; fw_vl , fw_hl) and the distance (d) of the locations of the measurements, a rotational angle (φ) and a rotational angular velocity (φ ') of the vehicle relative to this normally horizontal axis of rotation (A _x ; A _y ) are calculated, and - the calculated values for rotational angle ( φ) and rotational angular velocity (φ ') in response to vehicle-specific thresholds to generate and output control signals for driving safety systems in the vehicle. Method according to claim 1, characterized that as a driving-dependent Motion quantities accelerations (az_r, az_l; az_v, az_h) measured on the vehicle in its High direction act. Method according to claim 2, characterized that acceleration acting on the vehicle body (az_r, az_l; az_v, az_h). Method according to claim 2 or 3, characterized that from the measured accelerations (az_r, az_l, az_v, az_h) first the rotational angular velocity (φ ') is determined in order to determine the rotation angle (φ) from this below. Method according to claim 4, characterized that the calculation of rotational angular velocity (φ ') and rotation angle (φ) by means of Integration or by state observation using Kalman filters done. Method according to claim 2 or 3, characterized that from the measured accelerations (az_r, az_l, az_v, az_h) an absolute vehicle inclination or rotation angle (φ) below consideration the gravitational acceleration (g) by means of trigonometric relations is calculated. Method according to claim 1, characterized in that that as a driving-dependent Movement variables spring travel (fw_vr, fw_vl; fw_hr, fw_hl; fw_vr, fw_hr; fw_vl, fw_hl) in the range the vehicle wheels be measured. A method according to claim 7, characterized in that rotational angular velocities (φ ') of the vehicle about its longitudinal and / or transverse axis (Ax, Ay) is determined by deriving the spring travel (fw_vr, fw_vl; fw_hr, fw_hl; fw_vr, fw_hr; fw_vl, fw_hl) after the time taking into account the distances of the corresponding locations at which the spring travel (fw_vr, fw_vl; fw_hr, fw_hl; fw_vr, fw_hr; fw_vl, fw_hl). Method according to claim 9, characterized in that that from the continuously determined values for the rotational speeds (φ ') of the vehicle Rotation angle (φ) be determined. Method according to claim 7, characterized in that that from the spring paths (fw_vr, fw_vl; fw_hr, fw_hl; fw_vr, fw_hr; fw_vl, fw_hl) a relative vehicle tilt or rotation angle (φ) is calculated. Method according to one of the preceding claims, characterized characterized in that the values for rotation angle (φ) and Angular velocity (φ ') on various Be determined, and that for plausibility of the values for rotation angle (φ) and Angular velocity (φ ') all values determined considered become. Method according to one of the preceding claims, characterized characterized in that when evaluating the calculated values for rotation angle (φ) and Rotational angular velocity (φ ') describing the driving dynamics Sizes, like Vehicle lateral acceleration (ay), yaw rate, slip angle velocity, Vehicle speed (V_Fzg) and the like considered become.