DE102006048414B3 - Method and arrangement for detecting a rollover situation - Google Patents

Abstract

Method for detecting a rollover situation of a vehicle (1), in which a rollover situation is determined exclusively as a function of a lateral acceleration (ay) of the vehicle (1) and a roll rate (RR) about a longitudinal axis of the vehicle (1).

Description

The The present invention relates to a method and an arrangement for detecting a rollover situation of a vehicle.

Around suitable safety and restraint means in motor vehicles to be able to it is necessary a rollover or rollover situation of the vehicle in time to recognize. Rollover is understood essentially the vehicle rollover by a rotational movement of the vehicle about its longitudinal axis such that the vehicle on his side or his roof can tip over. This can be the case for example Slipping the wheels one side of the vehicle in a sand bed occur, with the in the sand entering side sinks and a rotation around the vehicle longitudinal axis can result. Another example would be driving up at high altitude Speed against an obstacle such as B. a crash barrier end, causing the wheels one side of the vehicle are thrown upwards and a rotation about one given by the two wheel contact points Axis of the other side of the vehicle can be done. Depending on the violence This event can lead to a rollover situation. Such an event will be for the algorithm interpretation for the detection of the respective critical ones Vehicle situation and triggering decision for a restraint system by a ramp crossing simulated. Further examples would be a slope drive or slipping the vehicle against a curb. All four Events (slides in a sand bed, curb stop, embankment drive and ramp crossing) can as representative for the Total of vehicle rollover events be accepted in the field.

Around in such a critical driving or accident situation safety and restraint measures for the Cause vehicle occupants, is a fast and reliable Recognizing the rollover situation necessary. In the past For this purpose, several acceleration sensors and a rotation rate sensor were used installed in the vehicle. Provide corresponding acceleration sensors continuously information for example about the inclination regarding an excellent vehicle axle or acceleration in a certain direction. Around a ramp crossing with possible To recognize a rollover situation has so far been a sensor in particular necessary, which measures a vertical acceleration of the vehicle. Under the vertical acceleration is usually understood a Acceleration in Z-direction, that is in the direction of gravitational acceleration. Usually becomes the longitudinal axis the vehicle is referred to as X-axis and pointing in the forward direction, a Y-axis runs then normal to the usual forward movement the vehicle to the left. The Z-axis of the vehicle then shows below. Thus, the X-axis can also be used as a longitudinal axis and the Y-axis as Transverse axis of the vehicle to be considered.

In The rule is always linear Y-acceleration vehicle available, as on the corresponding measurement data for trigger decision for z. B. steering wheel or passenger airbags or the side airbags used must become. additional Z-accelerometers are currently necessary to the window airbags in the rollover load case "ramp crossing" to control. All other load cases can be used alone from a roll rate sensor and the detection of Release y-acceleration. The Z-accelerometer bears significantly add to the cost of such security systems. Under Load case is a critical situation in the vehicle Safety device, such as an airbag, are triggered should.

The WO 99/473831 A1 discloses a method for detecting a rollover situation in which the value of a roll rate sensor is compared to a first threshold and the value of a lateral acceleration sensor is compared to a second threshold. Alternatively, it is proposed to compare the value of the roll rate sensor with a threshold value dependent on the lateral acceleration, or a combination of these two methods.

The DE 101 12 315 B4 discloses a method for determining a side roll-over of a vehicle and an occupant protection system in a vehicle in which a roll rate and a roll angle derived therefrom are examined for forming a combination of values that are beyond a critical threshold dependent on the lateral acceleration of the vehicle , In the process, it is finally investigated whether, for example, values for the roll rate are above or below a threshold dependent on the roll angle and the lateral acceleration; the larger the roll rate, the smaller the roll angle, a critical situation has already been reached. Here too, however, essentially the directly measured values of the sensors are used for the evaluation.

It Therefore, an object of the present invention is a method indicate that more reliable one Detects a rollover situation and uses as few acceleration input variables as possible.

These The object is achieved by a method according to claim 1.

Accordingly, a method is provided for detecting a rollover situation of a vehicle, in which a rollover situation exclusively in dependence on a lateral acceleration of the vehicle and a roll rate about a longitudinal axis of the vehicle ( 1 ), wherein the rollover situation is detected if a combination of simultaneously determined values of a first decision parameter and a second decision parameter coincides with stored critical combinations of values for the lateral acceleration and the roll rate, wherein the first decision parameter is determined by temporally deriving the lateral acceleration, by temporally integrating the lateral acceleration or by measuring a period for which the lateral acceleration increases, is determined.

The Invention allows thus the saving of one usually used Z-accelerometer, which is a significant financial Savings in controls of safety systems for motor vehicles means. It is sufficient to know the lateral acceleration of the vehicle, for example, accelerations, which act perpendicular to the acceleration of gravity and not in the direction of travel be measured. The roll rate is the angular velocity a rolling movement of the motor vehicle about an axis of rotation which in usually parallel to the vehicle's longitudinal axis runs. A possible For example, the axis of rotation is the axis through the support points of two wheels with traction while the one on the opposite Side present wheels of the vehicle on a ramp or floating.

The inventive method only requires a yaw rate sensor or a spin acceleration sensor and a linear acceleration sensor, wherein in particular the linear acceleration sensor usually always already exists in the vehicle.

It becomes a trigger decision for one Safety device, in particular a belt tensioner, side and / or window airbag hit, if the interlinked decision parameters exceed the threshold. in that the roll rate is determined by means of a rotation rate sensor or a spin acceleration sensor, wherein a spin is integrated to the spin rate, is measured.

It is in the inventive method possible, Assign known rollover situations to appropriate combinations. Thus, the critical combination of lateral acceleration values is preferred and the roll rate by measuring the lateral acceleration and the roll rate determined in a predetermined rollover situation of the vehicle.

Preferably the measured lateral acceleration is subjected to low-pass filtering, what high-frequency interference components eliminated at the measured acceleration. This disturbing vibrations, for example, due to natural oscillations of the vehicle or short Bumps up the shock absorbers occur can, not in the assessment of the existence of a rollover situation considered.

The Transverse acceleration is preferably near the center of gravity of the vehicle measured. Advantageously, a measurement of the lateral acceleration be measured at a particularly high point of the vehicle. The Use of Y-linear acceleration to detect the rollover situation is usually improved, The higher this is measured on the vehicle.

• a) Herbeiführen einer Rollover-Situation des Fahrzeugs;
• b) Messen der Rollrate um die X-Achse des Fahrzeugs und der Y-Beschleunigung des Fahrzeugs; und
• c) Speichern des ersten und zweiten Erkennungsparameters als kritische Kombination oder des dritten Erkennungsparameters als kritischen Schwellwert.

Preferably, the following method steps are carried out to determine the critical combination:

• a) causing a rollover situation of the vehicle;
• b) measuring the roll rate about the X-axis of the vehicle and the Y-acceleration of the vehicle; and
• c) storing the first and second detection parameters as the critical combination or the third detection parameter as the critical threshold.

The The invention further relates to an arrangement for detecting a rollover situation a vehicle with a linear acceleration sensor for measuring a lateral acceleration of the vehicle, a spin acceleration sensor or a yaw rate sensor for measuring a roll rate of the vehicle and a control device for evaluating the measured lateral acceleration the roll rate. It leads the control means an above-mentioned method for detecting a rollover situation of a vehicle.

In a preferred embodiment of the arrangement, the control device has a memory device with stored critical combinations of values of first and second decision parameters ters, for example, the lateral accelerations and the roll rate. If a measured combination of values of the lateral acceleration and the roll rate match one of the stored critical combinations, the control device generates a triggering signal for a safety device, in particular a side airbag of the vehicle.

Further advantageous embodiments of the invention are the subject of the dependent claims and the embodiments described below.

in the Furthermore, the invention is based on embodiments of the method and the arrangement explained in more detail with reference to the figures. It shows:

1 : the quantities considered in a rollover situation of a vehicle;

2 a block diagram of an embodiment of an inventive arrangement for detecting a rollover situation;

3 the variables of a rollover situation derived in a method according to the invention; and

4 : the temporal change of the roll rate and the lateral acceleration of a vehicle in a rollover situation.

In the figures are - if nothing else is stated - same or functionally identical elements provided with the same reference numerals Service.

In the 1 is the cross section of a vehicle 1 shown, with the vehicle with the wheels of a side on a ramp 2 ascended. In the 1 corresponds to the drawing plane of the YZ plane of the vehicle 1 , Through the driveway on the ramp 2 the vehicle makes a rotational movement about the support axis A, which is on a connecting line between the wheel contact points, not on the ramp 2 driven wheels, lies. The corresponding rotational movement with respect to the horizontal E is indicated by the arrow denoted by ω. A measuring sensor provided for measuring the rotational movement and in particular the linear transverse acceleration of the vehicle is denoted by the reference numeral 3 Mistake. It thus results for the position of the measuring sensor 3 from the position vector r → and the vector of the angular velocity ω → the path velocity from the vector product of the angular velocity ω → with the position vector r →: v → = ω → × r → (Equation 1)

By time derivation, the path acceleration a → results at the position of the acceleration sensor 3 in the vehicle too:

In usual Systems for the detection of a rollover situation the Z component of the orbit acceleration is detected, which with the web acceleration vector r → an angle α. A corresponding linear Z-acceleration sensor is unnecessary by application of the method according to the invention.

The 2 shows a block diagram of an embodiment of an inventive arrangement for detecting a rollover situation of a vehicle. The order 4 has a linear acceleration sensor 5 on, which measures a transversely acting to the vehicle or horizontally acting Y-acceleration. The order 4 has a rotation rate sensor 6 which detects a rolling rate RR of the vehicle, that is to say a rotation about the longitudinal axis of the vehicle. The roll rate can also be determined by integration of measured spin data of a spin sensor. Acceleration sensors are generally cheaper. The ones from the sensors 5 . 6 supplied values a _y , RR are a control device 7 fed. The control device 7 has a memory 9 for threshold values for critical combinations of the roll rate and a decision parameter derived from the Y acceleration, such as the integral of the Y acceleration over predetermined time interval lengths. The control device 7 is via a control line 10 with a safety device 8th For example, an airbag for the vehicle coupled. Provided by the control device 7 a rollover situation is detected, this sends a trigger signal FI to the airbag device 8th , which then unfolds and corresponding vehicle occupants at this Ge driving situation protects.

By the control device 7 is a method for detecting a rollover situation of a vehicle 1 carried out.

In the 3 the parameters used in carrying out the method are explained in more detail. In the 3 are the same names as in the 1 used, where a → T denotes the tangential portion of the acceleration about the axis of rotation A, which at the installation location of the acceleration sensors 3 acts. This is the direction of the web speed and the direction of the web acceleration of the rotary motion. The arrows SRZ and SRY indicate the sensing direction of a possible Z-sensor or a Y-sensor in the vehicle. A measurement signal which corresponds to a linear Z acceleration results from the product of the magnitude of the acceleration with the cosine of the rotational angle α: a z = | a → | cos α = acos α (Equation 3)

Out of the 3 resulting angle relationships can be a measured signal for the lateral acceleration, ie horizontally determined in the Y direction as proportional to the product of the amount of acceleration with the sine of the rotation angle α: a y = a · cos (90 ° -α) = -a · sin α (Equation 4)

From the equation 4 it follows that only by measuring a Y-acceleration and the spin can be derived. It also follows that the higher the installation position of the lateral acceleration sensor, ie the sensor for measuring the linear Y acceleration, the more the signal of the Y acceleration over that of the Z acceleration predominates because the absolute angle α is greater. This is from the 1 and 3 can be seen because with an increase in the mounting position of the corresponding sensor 3 the angle α between the position vector r and the horizontal E must increase.

According to the invention Decision algorithms conventionally applicable to the acceleration signals optionally in a modified form only to a Y-acceleration sensor signal applied to, for example, a ramp crash or a rollover situation to recognize.

In the 4 are the time courses of the rotation angle α, the roll rate RR and the lateral acceleration a _y (FIG. 4A . 4B ). Furthermore, in 4C the conventionally used time course of the Z acceleration a _z shown. In the 4A the angle α is given in degrees and the resulting roll rate in degrees / second. The accelerations a _y and a _z are given in units of gravitational acceleration g.

The time courses include driving a vehicle at high speed onto a one-sided ramp. As a result, the vehicle makes a left turn, which is in 4A is represented by the initially negative angle α. At about time t = 40 ms, the front wheels hit the ramp. In the time range marked HR, the ramp is ramped up. Until the time RTTF must be recognized by the controller, whether a rollover situation or a rollover situation for the vehicle exists. The Indian 4 case illustrated represents a vehicle rollover. From about 500 ms, the Z-acceleration is about 1 g, the vehicle is thus in free fall. Times greater than 1000 ms should not be considered here.

In order to trigger the safety systems of the vehicle reliably and in good time, a triggering decision must be made by the time RTTF (required time to fire). For this purpose, the control device continuously checks whether a selected decision criterion exceeds a respective threshold value. For example, it may be checked whether the roll rate RR and the Y acceleration a _y simultaneously exceed respective threshold values. If so, the controller sends 7 a trigger signal FI to the airbag 8th ,

A suitable criterion or a possible decision parameter for the trigger decision is also the product or the sum of the integrated Y acceleration with the measured roll rate. If this criterion then exceeds a predetermined threshold value, the control device generates 7 a trigger signal FI.

Based on 4C It can also be seen that instead of the conventional Z-acceleration signal can be used according to the invention on the Y-acceleration. The advantage of the method according to the invention and of the arrangement according to the invention for detecting the rollover situation is that a Z-acceleration sensor can be replaced without replacement. This can save a lot of hardware. Also, the test effort that the additional Z-sensor normally requires, is eliminated, since a Y-acceleration sensor is usually always present.

To the signal quality of the acceleration sensors 5 . 6 To improve, the signals a _y , RR may be optional before being evaluated by the controller 7 be low-pass filtered. As a result, higher-frequency natural oscillations of the vehicle, for example due to shock absorbers, can occur, can be suppressed.

A triggering decision can also be made such that initially in the memory 9 Data from typical crash situations where there is a rollover situation where Y acceleration and roll rate are being dropped. The control device 7 then compares the currently present measurement results RR and a _y with the stored critical combinations of these values and generates a triggering signal FI if, according to the critical combinations, an accident situation exists.

Although the present invention has been explained in more detail by means of embodiments, it is not limited thereto, but variously modifiable. In particular, any embodiments of the linear acceleration sensors and the rotation rate or rotational acceleration sensors are conceivable. For example, only the realization with piezo elements or micromechanical elements based on semiconductors is mentioned. Furthermore, the in the 4 Rollover situation illustrated by way of example only. When calibrating or setting threshold values for the triggering decision, deviating scenarios for bringing about predetermined rollover situations are possible.

Claims (9)

Method for detecting a rollover situation of a vehicle ( 1 ), wherein a rollover situation exclusively in dependence on a lateral acceleration (a _y ) of the vehicle ( 1 ) and a roll rate (RR) about a longitudinal axis of the vehicle ( 1 ), wherein the rollover situation is detected if a combination of simultaneously determined values of a first decision parameter and a second decision parameter coincide with stored critical combinations of values for the lateral acceleration (a _y ) and the roll rate (RR), characterized in that the first decision parameter is determined by temporally deriving the lateral acceleration (a _y ), by temporally integrating the lateral acceleration (a _y ) or by measuring a time period for which the lateral acceleration (a _y ) increases. Method according to claim 1, characterized in that that the second decision parameter by time derivation rolling rate (RR), by integrating the roll rate (RR) over time or by measuring a time period for which the roll rate (RR) increases, is determined. A method according to claim 1 or 2, characterized in that the roll rate by means of a rotation rate sensor or a spin acceleration sensor ( 6 ), in which a rotational acceleration is integrated to the rotation rate, is measured. Method according to one of the preceding claims, characterized in that the measured lateral acceleration (a _y ) is subjected to a low-pass filtering. Method according to one of the preceding claims, characterized in that the lateral acceleration (a _y ) in the vicinity of the center of gravity ( 3 ) of the vehicle ( 1 ) is measured. Method according to one of the preceding claims, characterized in that the critical combinations of values of the lateral acceleration (a _y ) and the roll rate (RR) by measuring the lateral acceleration (a _y ) and the roll rate (RR) in a predetermined rollover situation of the vehicle ( 1 ). Method according to one of the preceding claims, characterized in that the following method steps are carried out for determining the critical combinations: a) bringing about a rollover situation of the vehicle ( 1 ); b) measuring the roll rate (RR) about the X-axis of the vehicle ( 1 ) and the y-acceleration (a _y ) of the vehicle ( 1 ); and c) storing the respective combination of the decision parameter derived from the roll rate (RR) and the lateral acceleration (a _y ) as a critical combination. Arrangement ( 4 ) for detecting a rollover situation of a vehicle ( 1 ), comprising: a) a linear acceleration sensor ( 5 ) for measuring a lateral acceleration (a _y ) of the vehicle; b) a spin sensor ( 6 ) or a rotation rate sensor for measuring a roll rate (RR) of the vehicle; c) a control device ( 7 ) for evaluating the measured lateral acceleration (a _y ) and the roll rate (RR), wherein the control device ( 7 ) performs a method according to any one of claims 1-7. Arrangement according to claim 8, characterized in that the control device ( 7 ) a memory device ( 9 ) having stored critical combinations of values of the first and second decision parameters, and if a measured combination of values of the lateral acceleration (a _y ) and the roll rate (RR) matches one of the stored critical combinations, a trigger signal (FI) for a safety device ( 8th ), in particular a side airbag, of the vehicle ( 1 ) generated.