DE102011109632A1 - Method of operating driver assistance system of vehicle, involves plausibly evaluating yaw rate detected by sensor if deviation value of detected yaw rate and model yaw rate is smaller than maximum expected yaw rate deviation - Google Patents

Abstract

The method involves detecting speed, yaw rate and lateral acceleration of a vehicle (1) by sensors (3,4). A model yaw rate is determined according to sensed lateral acceleration and detected speed. The determined model yaw rate and detected yaw rate are compared. The detected yaw rate is plausibly evaluated if the deviation value of detected yaw rate and model yaw rate is smaller than a maximum expected yaw rate deviation.

Description

The invention relates to a method for operating a driver assistance system according to the features of the preamble of claim 1.

From the prior art, as in the DE 10 2004 017 638 A1 an apparatus and method for a vehicle, in particular a passenger car or a truck, for determining at least one crosswind influence of crosswind influence, which is generated by acting on the vehicle side wind, known. The apparatus comprises estimating means for estimating the at least one crosswinds value based on a lateral acceleration value and a yaw rate value based on a vehicle model. In this case, the lateral acceleration value is detected as a lateral acceleration sensor value using a lateral acceleration sensor and / or the yaw rate value as a yaw rate sensor value using a yaw rate sensor. The vehicle model is a linearized transverse dynamics single track model of the vehicle.

The invention is based on the object of specifying an improved method for operating a driver assistance system.

The object is achieved by a method for operating a driver assistance system having the features of claim 1.

Advantageous embodiments of the invention are the subject of the dependent claims.

In a method for operating a driver assistance system of a vehicle, a speed, a yaw rate and a lateral acceleration of the vehicle are detected by means of sensors.

According to the invention, a model yaw rate is determined by means of the detected lateral acceleration and the detected speed and compared with the detected yaw rate, and the detected yaw rate is considered plausible if its deviation from the model yaw rate is smaller than a maximum expected yaw rate deviation, which preferably depends on the speed is given. The determination of the model yaw rate is preferably based on a single-track model of the vehicle and preferably without taking into account the influence of a crosswind and / or a road bank on the yawing motion of the vehicle.

As a result of this plausibility check of the detected yaw rate, malfunctions of the driver assistance system, for example an electronic stability program of the vehicle or of a side wind disturbance compensating crosswind assist, ie. H. faulty interventions in functions of the vehicle, due to erroneously determined yaw rates avoided. Such erroneously determined yaw rates can occur, for example, due to a malfunction of a yaw rate sensor, due to road bends, for example when driving through a steep curve, due to crosswind forces, due to sensor deviations, so-called sensor offsets or due to other disturbances. If the detected yaw rate is not plausible, then it is not used for the functions of the driver assistance system, so that, for example, a risk of faulty braking due to a faulty yaw rate, which could endanger the vehicle occupants of the vehicle and other road users, is avoided.

Embodiments of the invention are explained in more detail below with reference to drawings.

Showing:

1 schematically a vehicle, and

2 schematically a diagram with a graphical representation of a yaw rate deviation and their individual shares.

Corresponding parts are provided in all figures with the same reference numerals.

1 schematically shows a vehicle 1 in plan view. The vehicle 1 has a driver assistance system 2 on, for example, a so-called electronic stability program, by means of which by targeted intervention in a brake system, in a drive train and / or in a steering system of the vehicle 1 Uncontrolled vehicle movements, such as understeer or oversteer of the vehicle 1 ie a breaking out or skidding of the vehicle 1 , prevented or at least reduced.

For the proper functioning of the driver assistance system 2 is a detection of a yaw rate ψ. _{g of} the vehicle 1 required. For this purpose, the vehicle points 1 at least one yaw rate sensor 3 for yaw rate detection. When detecting the yaw rate ψ. _g it may lead to errors, for example due to a malfunction of the yaw rate sensor 3 , due to road bends φ, for example when driving through a steep curve, due to crosswind forces, due to sensor deviations, so-called sensor offsets or due to further disturbances. An erroneously detected yaw rate ψ. _g may cause malfunction of the driver assistance system 2 lead, ie, for example, to incorrect interventions in the brake system, in the drive train and / or in the steering system of the vehicle 1 , This can endanger the vehicle occupants of the vehicle 1 and for other road users.

For example, when traversing a banked curve, the detected yaw rate ψ will fit. _g and one by means of at least one lateral acceleration sensor 4 detected lateral acceleration α y / Sens of the vehicle 1 not together in a manner calculated from a linear one-track model. If, for example, a vehicle drives at 200 km / h through a steep bend with a 31 ° bank and a radius of 600 m, this is done without lateral acceleration, since a centrifugal force and a downhill force compensate each other. This would be a malfunction of the driver assistance system 2 lead, ie, for example, to incorrect interventions in the brake system, in the drive train and / or in the steering system of the vehicle 1 ,

It is therefore of particular advantage that the means of the yaw rate sensor 3 detected yaw rate ψ. _g) for plausibility and to evaluate in order to avoid or at least significantly reduce the risk of such malfunction. Is the by means of the yaw rate sensor 3 detected yaw rate ψ .g rated as not plausible, it is for those of the yaw rate ψ. _g dependent functions of the driver assistance system 2 not used, ie functions of the driver assistance system 2 , which at the detected yaw rate ψ. _g are deactivated until the detected yaw rate ψ. _{g is} again considered plausible.

The plausibility check by means of the yaw rate sensor 3 detected yaw rate ψ. _g is used in a method for operating the driver assistance system 2 of the vehicle 1 performed, which is explained in more detail below. In the process, by means of the yaw rate sensor 3 the yaw rate ψ. _{g of} the vehicle 1 and by means of the lateral acceleration sensor 4 the lateral acceleration α y / Sens of the vehicle 1 detected. Furthermore, the speed v of the vehicle 1 detected. By means of the detected lateral acceleration α y / Sens and the detected velocity v becomes a model yaw rate ψ. determined and with the detected yaw rate ψ. _g , wherein the detected yaw rate ψ. _{g is} considered plausible if it falls within an upper deviation limit ψ. _max and a lower deviation limit ψ. ψ _min a deviation from the model yaw rate. lies, ie the model yaw rate ψ. not above the upper deviation limits ψ. exceeds _max out or not ψ below the lower deviation limits. _min below.

The deviation limits ψ. _max , ψ. _min are set such that uncertainties in the above-described interfering factors influencing the yaw rate detection, that is, malfunction of the yaw rate sensor 3 , Road bends φ, lateral wind forces, sensor offsets or other disturbances are taken into account. Ie. Deviations of the detected yaw rate ψ. _g from the model yaw rate ψ. due to such factors are up to the predetermined deviation limits ψ. _max , ψ. _min , so that due to these factors only slightly erroneously detected yaw rate ψ. _{g is} still considered to be plausible, since these slight deviations do not lead to serious malfunctions of the driver assistance system 2 to lead.

To simplify modeling and simplify its determination, the model yaw rate ψ. expediently determined on the basis of a so-called linear one-track model.

The model yaw rate ψ. is determined without consideration of an influence of a crosswind and / or a lane bank φ, so that these influences, which are responsible for the erroneous detection of the yaw rate ψ. _g by means of the yaw rate sensor 3 when comparing the detected yaw rate ψ. _g with the determined model yaw rate ψ. can be detected and the detected yaw rate ψ. _g , if it is corrupted due to such influences, evaluated as not plausible and for the functions of the driver assistance system 2 not used.

The deviation limits ψ. _max , ψ. _min , up to which the detected yaw rate ψ. _g from the determined model yaw rate ψ. may vary, are expediently given speed-dependent, since at least some of the above-mentioned influencing factors which lead to the erroneous detection of the yaw rate ψ. _g , have a speed-dependent influence of different magnitude.

The procedure and its basics are explained in more detail below. As a basis for the derivation of the model yaw rate ψ. or for plausibility of the detected yaw rate ψ. _g by means of the determined model yaw rate ψ. serve the momentum conservation law and the angular momentum or spin law of the linear one-track model: (β. + ψ.) vm = F _V + F _H + F _W - mgφ [1] J _zz ψ .. = F _V 1 _V - F _H 1 _H + eF _W [2] where β is a slip angle of the vehicle 1 is and thereby β. a float angle rate, m a mass of the vehicle 1 , F _{v is} a lateral force on a front axle of the vehicle 1 F _{H is} a lateral force on a rear axle of the vehicle, F _{W is} a wind force, g is the gravitational acceleration, J _{ZZ is} a vehicle-dependent yaw moment of inertia, ψ .. a yaw angular acceleration, l _{V is} a vehicle-dependent distance of a center of gravity of the vehicle 1 to the front axle, l _{H is} a vehicle-dependent distance of a center of gravity of the vehicle 1 to the rear axle and e a vehicle-dependent Störkrafthebelarm the wind power F _W.

wobei α_H ein Schräglaufwinkel der Hinterachse des Fahrzeugs 1 ist und c_H eine fahrzeugabhängige Schräglaufsteifigkeit der Hinterachse des Fahrzeugs 1.In addition, a slip angle side force relationship is needed on a rear axle of the vehicle:

where α _{H is} a slip angle of the rear axle of the vehicle 1 and c _{H is} a vehicle-dependent skew stiffness of the rear axle of the vehicle 1 ,

wobei l ein Abstand zwischen den Achsen des Fahrzeugs 1 ist.If equation [2] is changed to F _V and F _V and F _{H are used} in the spin set, the result is:

where l is a distance between the axles of the vehicle 1 is.

The means of the lateral acceleration sensor 4 detected lateral acceleration α y / Sens can be written as: α y / Sens = (β. + ψ.) v + gφ [5]

wobei β .. eine Schwimmwinkelbeschleunigung ist und eine erste Ableitung der erfassten Querbeschleunigung α y / Sens .If equation [5] becomes β. converted and once derived, then the following two equations result:

where β .. is a float angular acceleration and a first derivative of the detected lateral acceleration α y / Sens ,

wobei ψ ... eine dritte Ableitung eines Gierwinkels des Fahrzeugs 1 ist.The two equations [6] and [7] inserted into the time derivative of equation [4] yields:

where ψ ... is a third derivative of a yaw angle of the vehicle 1 is.

wobei F ._W ein Windkraftgradient ist.If the equation [8] is Laplace transformed, the Laplace transformation here only in relation to the detected lateral acceleration α y / Sens and the model yaw rate ψ. is applied, the transfer function results between the detected lateral acceleration α y / Sens and the model yaw rate ψ.:

where F. _{W is} a wind power gradient.

berechnen, dann würde die berechnete Modellgierrate ψ . von der tatsächlichen Gierrate ψ ._tatsächlich abweichen, wobei, wie im Folgenden erläutert, festgestellt werden kann, dass die maximale Abweichung durch die folgende Gleichung [12] bestimmt werden kann.If the vehicle parameters and the crosswind gradient F. _W , as well as the roadway traffic φ of the roadway exactly known, then the model yaw rate calculated with the above equation would be ψ. very close to the actual vehicle yaw rate ψ. _actually fit. If the unknown sizes crosswind gradient F. _W and road bank angle φ and change the model parameters, as they may occur, for example, in a load change or tire change, disregard, and the model yaw rate ψ. accordingly according to the simplified model equation resulting from equation [9]

calculate, then the calculated model yaw rate would be ψ. from the actual yaw rate ψ. _actually , and as explained below, it can be determined that the maximum deviation can be determined by the following equation [12].

Since the model parameters can vary, for example, by loading or a tire change, and also external disturbances on the vehicle 1 act, is about the model yaw rate ψ. a band is laid in which the deviations are considered admissible, ie a predetermined limit value of the permissible deviation or an upper deviation limit value ψ. _max and lower deviation limit ψ. _{min of} the permissible deviation from the determined model yaw rate ψ. The road bank angle φ, the wind force gradient F, must be taken into account. _W and the sensor offsets of yaw rate ψ. _g and lateral acceleration α y / Sens , The temporal wind force gradient F. _W is speed dependent. To arrive at a speed-independent variable, F. _{W divided} by the speed ν:

wobei ΔF_W,max ein maximaler Seitenwindgradient ist, der einstellbar ist und ein durch Fahrtests optimierbarer Parameter ist. Dieser Parameter gibt an, mit welchem maximalen Seitenwindgradienten man in der Praxis rechnen kann. α_y,Offset,max ist der maximale Sensoroffset des Querbeschleunigungssensors 4. Er ist einstellbar und ein durch Fahrtests optimierbarer Parameter. Dieser Parameter gibt an, mit welchem maximalen Wert für die Kombination aus Offset und Fahrbahnquerneigung ϕ des Querbeschleunigungssensors 4 man in der Praxis rechnen kann. ψ ._y,Offset,max ist ein maximaler Gierratenoffset des Gierratensensors 3. Er ist einstellbar und ein durch Fahrtests optimierbarer Parameter. Dieser Parameter gibt an, mit welchem maximalen Gierratenoffset man in der Praxis rechnen kann.A maximum allowable sensor offset α _{y, offset,} α _max for the transverse acceleration y / Sens and the maximum permissible value for the road bank φ can be converted into each other. Here, the value for the maximum sensor offset α _{y, offset, max of} the lateral acceleration α y / Sens used. From the maximum allowable values for α _{y, Offset, max} , ψ. _{y, Offset, max} and ΔF _{W, max} , the width of the yaw rate band over the speed can be determined. In general:

where ΔF _{W, max is} a maximum crosswind gradient _that is adjustable and is a parameter that can be optimized by driving tests. This parameter indicates the maximum crosswind gradient that can be expected in practice. α _{y, offset, max} is the maximum sensor offset of the lateral acceleration sensor 4 , It is adjustable and can be optimized by driving tests parameters. This parameter specifies the maximum value for the combination of offset and road bank angle φ of the lateral acceleration sensor 4 you can count on in practice. ψ. _{y, Offset, max} is a maximum yaw rate _{offset of} the yaw rate sensor 3 , It is adjustable and can be optimized by driving tests parameters. This parameter indicates the maximum yaw rate offset that can be expected in practice.

der Gleichung [12] gebildet wird, der zweite Anteil A2 aus dem zweiten Term

der Gleichung [12] gebildet wird und der dritte Anteil A3 aus dem dritten Term |ψ ._y,Offset,max| der Gleichung [12] gebildet wird.The yaw rate deviation Δψ. from the model yaw rate is, as in 2 shown, speed-dependent. In the diagram shown here, the yaw rate deviation is Δψ. represented as well as the resulting from the equation [12] shares A1, A2, A3, from which the yaw rate deviation .DELTA.ψ. composed, wherein the first portion A1 from the first term

the equation [12] is formed, the second part A2 from the second term

is formed of the equation [12] and the third portion A3 from the third term | ψ. _{y, offset, max} | the equation [12] is formed.

The velocity ν is a function of the time t: ν = ν (t) [13]

oder vereinfacht: Δψ .(t) = c1·ν(t) + c2·1/ν(1) + c3 [15] mit

c2 = |α_y,Offset,max| [17] c3 = |ψ ._y,Offset,max| [18] The deviation Δψ. (T) is therefore also a function of time. The following applies:

or simplified: Δψ. (T) = c1 · ν (t) + c2 · 1 / ν (1) + c3 [15] With

c2 = | αy _{, offset, max} | [17] c3 = | ψ. _{y, offset, max} | [18]

In practice, a is used to calculate the model yaw rate ψ. provided processor may be programmed such that it does not use the Laplace function ψ. (s), but the associated time function rück. (t) transformed back into the time domain as a model yaw rate ψ. calculated.

The invention is thus based on the finding that one has a yaw rate zu measured at a time t. _g (t) of the vehicle 1 can check for plausibility by using the transverse acceleration α measured at this time t y / Sens (t) and velocity ν (t) compute a model yaw rate ψ. (t), wherein the calculation is based on a one-track model and the effects of the crosswind F _W and the road bank φ are disregarded by further selecting one of the Velocity ν (t) dependent, maximum expected yaw rate deviation ψ. (T) is determined and by using the yaw rate sensor 3 detected yaw rate ψ. _g (t) is considered to be plausible if its deviation from the model yaw rate ψ (t) is less than the maximum expected yaw rate deviation Δψ (t), ie, if the detected yaw rate ψ. _g (t) lies in the yaw rate band ψ. (t) ± Δψ. (t) and is considered implausible if it lies outside the yaw rate band ψ. (t) ± Δψ. (t).

As a result, two yaw rate limits dependent on the calculated model yaw rate ψ (t) and velocity ν (t) are determined, an upper deviation limit ψ. _max (t) and a lower deviation limit ψ. _min (t): ψ. _max (t) = ψ. (t) + Δψ. (t) [19] ψ. _min (t) = ψ. (t) - Δψ. (t) [20]

Subsequently, it is checked whether the detected yaw rate ψ. _g (t) between these limits ψ. _max (t) and ψ. _max (t) is. If so, the detected yaw rate ψ. _g (t) considered as plausible, otherwise as implausible.

The yaw rate deviation Δψ. (T) has a speed-dependent curve according to equation [15], wherein the parameters c1, c2 and c3 can be determined according to equations [16], [17] and [18] and / or based on driving tests.

LIST OF REFERENCE NUMBERS

1

vehicle

2

Driver assistance system

3

Yaw rate sensor

4

Lateral acceleration sensor

A1

first share

A2

second share

A3

third share

v

speed

Δψ.

Yaw rate deviation

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004017638 A1 [0002]

Claims (5)

Method for operating a driver assistance system ( 2 ) of a vehicle ( 1 ), A velocity (v), a yaw rate (ψ _g.) And a lateral acceleration (α y / Sens ) of the vehicle are detected by means of sensors, characterized in that by means of the detected lateral acceleration (α y / Sens ) And the detected speed (v) a model yaw rate (ψ.) Is determined, and (with the detected yaw rate ψ. _G) is compared, and that the detected yaw rate (ψ _g.) Is judged to be plausible if their deviation from the model yaw rate ψ. (t) is smaller in magnitude than a maximum expected yaw rate deviation Δψ. (t). Method according to Claim 1, characterized in that functions of the driver assistance system ( 2 ), Which (on the sensed yaw rate ψ .g) is based, will be disabled until the detected yaw rate (ψ _g.) Is judged to be plausible. A method according to claim 1 or 2, characterized in that the model yaw rate (ψ) is determined without consideration of an influence of a crosswind and / or a road bank (φ). Method according to one of Claims 1 to 3, characterized in that the maximum expected yaw rate deviation Δψ (t) is predetermined as a function of the speed. Method according to one of the preceding claims, characterized in that the model yaw rate (ψ) is determined on the basis of a linear one-track model of the vehicle.

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