Method for operating a driver assistance device and corresponding driver assistance device

Abstract

Method for operating a driver assistance device (1) of a motor vehicle, comprising the steps: - Recording at least four measurements, in particular a lateral acceleration (a m ), a yaw rate (ω m ), a speed (v m ) and a steering angle (δ m ) of the motor vehicle, using at least one sensor device, - Calculating a first subsurface inclination angle (α1), a second subsurface inclination angle (α2) and a third subsurface inclination angle (α3), each from a subset of measurements consisting of a maximum of three of the recorded measurements (a m ,ω m ,v m ,δ m ) consists of which at most two of the measured values ​​(a m ,ω m ,v m ,δ m ) are contained in one of the other measurement subsets, and - Determining a first subsurface assessment parameter (b1) based on the first and second subsurface inclination angles (α1,α2) and a second subsurface assessment parameter (b2) based on the first and third subsurface inclination angles (α1,α3).

Description

[0001] The invention relates to a method for operating a driver assistance system of a motor vehicle. It further relates to a corresponding driver assistance system. State of the art

[0002] Methods of the type mentioned above are known from the prior art. They serve to operate the driver assistance system, which is designed, for example, as an ABS, TCS, or ESP system. During the execution of the method, at least one measured value is typically determined, from which a driving state of the vehicle is determined or can be derived. Because the reliable function of the driver assistance system is of great importance for the safety of the vehicle, the measured value is usually validated. For this purpose, at least one reference value is generated from mathematical models, which can be used to verify the measured value. If the measured value deviates too much from the reference value, an error in the measured value is concluded.

[0003] One such method is described, for example, in DE 196 36 443 A1. However, this method has the limitation that the commonly used mathematical models are only valid in a plane, i.e., when the vehicle is on a level surface. For the purposes of this description, a level surface is understood to mean, for example, the vehicle's standing surface, which has a surface normal that at least approximately coincides with or is parallel to a gravity vector. The models' limited validity to a level surface can therefore lead to the measured value being incorrectly considered erroneous if the vehicle is not on a level surface, i.e., if it is driving on a banked curve or on a road with a superelevation.It is therefore desirable to extend the method known from DE 196 36 443 A1 to include steep curve detection, i.e., detection of whether the motor vehicle is on a surface that is inclined relative to a flat surface. An inclined surface is understood to be, for example, a vehicle's standing surface which has a surface normal that does not coincide with the gravity vector.

[0004] Such steep-curve detection could, for example, be used to deactivate the plausibility check of the measured value and / or to widen the tolerance band used for the measured value when the surface is inclined. Naturally, any inclined surface can be advantageously detected using steep-curve detection; it is therefore not limited to steep curves per se. The challenge here is that steep-curve detection must not depend on the measured value being validated. Such a dependency could lead to an erroneous detection of an inclined surface due to a faulty measured value, even though the surface is actually level. This would accordingly lead to the deactivation of plausibility checks or a widening of the tolerance band for the measured value.Consequently, with such a procedure, the driver assistance system no longer has the ability to determine whether the measured value is erroneous. This must be avoided under all circumstances, especially when multiple measured values ​​need to be validated.

[0005] The publication DE 103 11 794 A1 describes a method and a device for determining an influencing factor affecting the driving dynamics of a motor vehicle.

[0006] The publication DE 10 2006 061 249 A1 describes a method and a device for determining a friction coefficient.

[0007] The publication DE 196 36 443 A1 describes a device and a method for monitoring sensors in a vehicle. Disclosure of the invention

[0008] In contrast, the method for operating a driver assistance device with the features of claim 1 has the advantage that reliable steep curve detection is possible for multiple measured values, wherein the steep curve detection is not dependent on the plausibility check.

[0009] The measured value is dependent on the measured value. This is achieved according to the invention by carrying out the following steps: Acquiring at least four measured values, in particular a lateral acceleration, a yaw rate, a speed and a steering angle of the motor vehicle, using at least one sensor device; calculating a first ground inclination angle, a second ground inclination angle and a third ground inclination angle, each from a subset of measured values ​​consisting of a maximum of three of the acquired measured values, of which at most two measured values ​​are contained in one of the other subsets of measured values; and determining a first ground evaluation parameter based on the first and the second ground inclination angles and a second ground evaluation parameter based on the first and the third ground inclination angles.

[0010] The sensor device serves to acquire the measured values. It typically has a separate sensor for each measured value. Of course, several sensor devices can alternatively be provided, in particular one sensor device for each measured value. When acquiring the measured values, actual physical quantities are preferably determined directly; thus, it is not initially intended to determine at least one of the measured values ​​indirectly from other measured values. For the banked curve detection, at least four, in particular exactly four, measured values ​​are acquired, namely preferably a lateral acceleration, a yaw rate, a velocity, and a steering angle.

[0011] The lateral acceleration of a motor vehicle is measured in its lateral direction, meaning it is perpendicular to both a longitudinal and a vertical direction. The lateral direction is, for example, at least approximately parallel to the ground the vehicle is on. The yaw rate of the motor vehicle describes its rotational speed around a vertical yaw axis, while the vehicle's speed is its speed in the longitudinal direction. Finally, the steering angle describes the steering angle set by the driver and / or a driver assistance system at the vehicle's wheels.Preferably a lateral acceleration sensor is provided for detecting the lateral acceleration, a yaw rate sensor for detecting the yaw rate, a speed sensor for detecting the speed, and a steering angle sensor for detecting the steering angle, which are, for example, assigned to the sensor device.

[0012] From the at least four recorded measurements, three subsurface slope angles are then determined, using a subset of the measurements for each angle. Each subset contains a maximum of three of the recorded measurements. The composition of each subset differs from the composition of the other subsets. Accordingly, each subset may contain a maximum of two measurements that are also present in one of the other subsets. Therefore, if four measurements x1, x2, x3, and x4 are provided, the relationships for the first subsurface slope angle α1 can be expressed as α1 = f(x1, x2, x3), for the second subsurface slope angle α2 as α2 = f(x1, x3, x4), and for the third subsurface slope angle α3 as α3 = f(x2, x3, x4).

[0013] The first subsurface slope angle is calculated from the first subset of measurements, which consists of at most three of the recorded measurements. The second subsurface slope angle is calculated from the second subset of measurements, which also consists of at most three of the recorded measurements, with at most two of these measurements also being included in the first subset. Finally, the third subsurface slope angle is determined from the third subset of measurements, which also consists of at most three of the recorded measurements, but with at most two of these measurements also being included in the first subset and at most two of these measurements in the second subset. Accordingly, three subsurface slope angles are determined, each dependent on different measurements, thus ensuring plausibility checks.Additionally, a fourth subsurface inclination angle can be determined from the dependency α4 = f(x1, x2, x4). However, this is optional.

[0014] Subsequently, two of the subsurface slope angles are used to determine at least two subsurface assessment parameters. For example, the first subsurface assessment parameter is based on the first and second subsurface slope angles, the second subsurface assessment parameter on the first and third subsurface slope angles, and—if applicable—a third subsurface assessment parameter on the first and fourth subsurface slope angles. For example, when determining each subsurface assessment parameter, it is ascertained whether the subsurface slope angles used are identical or at least whether the difference between them is less than a predefined tolerance. This tolerance can be determined either absolutely or relative to one of the subsurface slope angles used.

[0015] If this condition is met, one of the considered ground slope angles, or an average of both ground slope angles, is compared to a limit value. If the ground slope angle exceeds the limit value, the ground assessment value is set. If the ground slope angle is smaller than the limit value, or if the considered ground slope angles do not match or differ too greatly, the ground assessment value is reset. The ground assessment value is therefore a two-valued Boolean variable that indicates whether the vehicle is on a sloped or level surface.

[0016] Based on this subsurface assessment parameter, the plausibility check of at least one of the measured values ​​can then be performed or deactivated, or a corresponding tolerance can be selected. The tolerance is preferably chosen to be larger the greater the subsurface inclination angle. For the plausibility check, the subsurface assessment parameter used is always the one that is based on at least one subsurface inclination angle that is independent of the measured value being checked for plausibility.

[0017] In general terms, a number n of measurements are to be acquired using at least one sensor device. Of these n measurements, a number m, less than n, are to be validated. Accordingly, at least m+1 subsurface slope angles are to be calculated, of which at least one is independent of the measurement being validated. Each subsurface slope angle is calculated from a subset of measurements corresponding to a permutation of n-1 of the acquired measurements. Thus, at most n subsets of measurements and the resulting subsurface slope angles can be determined. From at least two of the subsurface slope angles, a subsurface evaluation parameter is then determined, which is used to validate the measurement. At least one of the subsurface slope angles used is independent of the measurement being validated.

[0018] A further development of the invention provides that the first ground inclination angle is calculated from the measured values ​​for the lateral acceleration, the yaw rate, and the velocity. Thus, α1 = f(a m , ω m , v m ), where a is the lateral acceleration, w is the yaw rate, and v is the velocity. The subscript m always denotes a measured quantity, i.e., one of the measured values.

[0019] A further development of the invention provides that the second ground inclination angle is calculated from the measured values ​​for lateral acceleration and velocity, as well as from a first model parameter, which is determined at least on the basis of the measured values ​​for velocity, lateral acceleration, and steering angle. Thus, α2 = f(a m , v m , M1), where M1 is the first model variable for which the dependence M1 = f(v m , a m , δ m ) applies. In summary, this corresponds to α2 = f(am , v m , δ m It thus becomes clear that the second ground tilt angle, unlike the first ground tilt angle, depends on the steering angle, but not on the yaw rate.

[0020] A further development of the invention provides that the third ground inclination angle is calculated from the measured values ​​for the yaw rate and the speed, as well as from a second model parameter, which is determined at least on the basis of the measured values ​​for the speed, the yaw rate, and the steering angle. Here, α3 = f(ω) applies. m , v m , M2) with the second model quantity M2 = (v m , ω m , δ m In summary, this corresponds to α3 = f(ω). m , v m , δ2). The third substrate inclination angle therefore does not depend on the lateral acceleration.

[0021] A further development of the invention provides that the first subsurface inclination angle is determined based on the inclination angle relationship sin(α)=ay−ωzvxg is determined, where the first subsurface inclination angle α is used as the subsurface inclination angle, and the lateral acceleration a is used as the lateral acceleration. y the measured value for the lateral acceleration, as yaw rate ω z the measured value for the yaw rate and as velocity v x The measured value for the velocity is used. Accordingly, the following applies to the angle of inclination relationship for determining the first subsurface inclination angle α = α1, a y = a m , ω z = ω m and v x = v m The quantity g is the gravitational acceleration.

[0022] A further development of the invention provides that the second subsurface inclination angle is determined based on the inclination angle relationship, wherein the subsurface inclination angle α is the second subsurface inclination angle, and the lateral acceleration a is they the measured value for lateral acceleration, expressed as velocity v x the measured value for speed and as yaw rate ω z The first model parameter is used. To determine the second subsurface slope angle, the aforementioned slope angle relationship is used. Here, α = α2, a y = α m , v x = v m and ω z = M1.

[0023] A further development of the invention provides that the third subsurface inclination angle is determined based on the inclination angle relationship, wherein the subsurface inclination angle α is the third subsurface inclination angle, and the yaw rate ω is the subsurface inclination angle. z the measurement rate for the yaw rate, as velocity v x the measured value for speed and as lateral acceleration a y The second model size is used. Here too, the aforementioned tilt angle relationship applies. In this case, α = α3 ω z = ω m, v x = v m and a y = M2.

[0024] A further development of the invention provides that the first model size is determined based on the relationship M1=vml(δm−lamvc2) is determined, where I is the axle spacing and v c the characteristic speed of the motor vehicle, and / or that the second model quantity is determined by the relationship M2=vc2δml−vc2ωmvm is determined.

[0025] The axle spacing I, which can also be called wheelbase, denotes the distance between the axles of the motor vehicle, in particular between a front axle and a rear axle. The characteristic speed v c This describes the speed of a motor vehicle at which it exhibits maximum yaw gain. It can be derived from the relationship vc=lEG to be determined. Here, I denotes the wheelbase and EG the self-steering gradient. The latter describes the steady-state self-steering behavior of two-track motor vehicles. The characteristic speed is usually determined during development in a driving test. For example, a steady-state circular driving maneuver is carried out at different vehicle speeds. Both the wheelbase I and the characteristic speed v are determined. c are constant for the motor vehicle. Accordingly, the model parameters are each based on only three variable parameters, which are each selected from the recorded measurements.

[0026] A further development of the invention provides that the first subsurface evaluation parameter is used for yaw rate monitoring and the second subsurface evaluation parameter for lateral acceleration monitoring, in particular for interrupting the respective monitoring when a sloping subsurface is present and / or for determining a permissible tolerance for the monitoring. As already explained at the outset, the subsurface evaluation parameters reflect the slope of the subsurface or indicate whether a slope is present or whether the subsurface is flat. The first subsurface evaluation parameter is determined from the first and second subsurface slope angles, the latter being independent of the yaw rate. In contrast, the second subsurface evaluation parameter is based on the first and third subsurface slope angles. The latter is independent of the lateral acceleration.

[0027] Accordingly, the respective ground condition parameter used for monitoring—that is, for yaw rate monitoring or lateral acceleration monitoring—is independent of the measured value being monitored. Therefore, it is impossible for monitoring to be deactivated and / or the tolerance for the measured value to be increased because the value contains an error. Thus, even when the ground is inclined, for example, on a banked curve and / or on an inclined plane, reliable monitoring of the yaw rate using the first ground condition parameter and of the lateral acceleration using the second ground condition parameter can always be performed. When monitoring is inclined, it is preferable to temporarily interrupt or deactivate the monitoring and / or adjust the permissible tolerance accordingly, usually by increasing it.

[0028] The invention further relates to a driver assistance device of a motor vehicle, in particular for carrying out the method according to the foregoing descriptions, wherein the driver assistance device is provided to perform the following steps: acquiring at least four measured values, in particular a lateral acceleration, a yaw rate, a speed and a steering angle of the motor vehicle, using at least one sensor device; calculating a first ground inclination angle, a second ground inclination angle and a third ground inclination angle, each from a subset of measured values ​​consisting of a maximum of three of the acquired measured values, of which at most two measured values ​​are contained in one of the respective other subsets of measured values;and determining a first subsurface assessment parameter based on the first and second subsurface inclination angles and a second subsurface assessment parameter based on the first and third subsurface inclination angles. The method used may be further developed according to the above explanations. The advantages of such a procedure have already been discussed, so reference is made to the above explanations in this respect.

[0029] The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The only embodiment shown is... Figure a schematic representation of a method for operating a driver assistance system of a motor vehicle.

[0030] The figure illustrates the method for operating a driver assistance device 1, in which four measured values, namely a yaw rate ω m, a speed v m , a lateral acceleration a m and a steering angle δ m A first background rating parameter b1 and a second background rating parameter b2 are determined. The aforementioned measured values ​​are determined using a sensor device not shown here. The measured values ​​are then fed to a calculation unit 2 of the driver assistance system 1. It becomes clear that, within the framework of a calculation function 3, a first model parameter M1 is derived from the measured values ​​for the speed v. m , for the lateral acceleration a m and for the steering angle δ m is calculated. Similarly, a second model parameter M2 is calculated from the measured values ​​for the yaw rate ω using a calculation function 4. m , the velocity v m and the steering angle δ m calculated.

[0031] Subsequently, within the framework of calculation functions 5, 6, and 7, a first subsurface inclination angle α1, a second subsurface inclination angle α2, and a third subsurface inclination angle α3 are determined. The first subsurface inclination angle α1 is directly derived from the measured values ​​for the yaw rate ω. m , the velocity v m and the acceleration a m The relationship between the angle of inclination is determined. sin(α1)=am−ωmvmg

[0032] The equation used here is g, where g denotes the gravitational acceleration. A similar tilt angle relationship is also generally used to determine the second subsurface tilt angle α2, although here the first model quantity M1 is used as the yaw rate, so that the second subsurface tilt angle does not depend on the measured value for the yaw rate ω. m depends, but is a function of the measured values ​​for speed v m , the lateral acceleration a mand the steering angle δ m is present. Accordingly, the following applies: sin(α2)=am−M1vmg.

[0033] The determination of the third subsurface inclination angle α3 is also based on the inclination angle relationship, whereby the following holds: sin(α3)=M2−ωmvmg.

[0034] Therefore, the third substrate inclination angle is not dependent on the measured value for the lateral acceleration a. m dependent, but lies as a function of the measured values ​​for the yaw rate ω m , the velocity v m and the steering angle δ m before.

[0035] Within the framework of evaluation functions 8 and 9, the subsurface assessment parameters b1 and b2 are determined. Evaluation function 8 is fed the first subsurface inclination angle α1 and the second subsurface inclination angle α2. It assesses whether the subsurface inclination angles α1 and α2 are equal or at least whether the difference between them is less than a tolerance. If this is the case, it is checked whether the first subsurface inclination angle α1 or the second subsurface inclination angle α2 is greater than a limit value. If this is the case, the first subsurface assessment parameter b1 is set; otherwise, it is reset. The same procedure is followed in evaluation function 9 for the second subsurface assessment parameter b2, whereby evaluation function 9 is fed the first subsurface inclination angle α1 and the third subsurface inclination angle α3. Here, too, it is assessed whether the subsurface inclination angles α1 and α3 are equal or at least similar.Subsequently, at least one of the subsurface inclination angles α1 and α3 is checked to see if it exceeds the limit value. If so, the second subsurface evaluation parameter b2 is set; otherwise, it is reset.

[0036] Additionally, it may be provided that the subsurface assessment parameter b1 or b2 is reset if the check within the framework of evaluation function 8 or 9 shows that the respective subsurface inclination angles α1 and α2 or α1 and α3 used are not equal or the difference exceeds the tolerance.

[0037] The first background parameter b1 is used for yaw rate monitoring, and the second background parameter b2 for lateral acceleration monitoring. This approach has the advantage of eliminating any interdependence between the measured value being monitored and the calculation of the respective background parameter b1 or b2. Optionally, the method described above can be extended. For example, a roll rate signal can be generated or a reference attitude angle determined, which can be used for other functions, though preferably not for monitoring functions.

Claims

[1] Method for operating a driver assistance device (1) of a motor vehicle, comprising the steps: - Recording at least four measurements, in particular a lateral acceleration (a m ), a yaw rate (ω m ), a speed (v m ) and a steering angle (δ m ) of the motor vehicle, using at least one sensor device, - Calculating a first subsurface inclination angle (α1), a second subsurface inclination angle (α2) and a third subsurface inclination angle (α3), each from a subset of measurements consisting of a maximum of three of the recorded measurements (a m ,ω m ,v m ,δ m ) consists of which at most two of the measured values ​​(a m ,ω m ,v m ,δ m ) are contained in one of the other measurement subsets, and - Determining a first subsurface assessment parameter (b1) based on the first and second subsurface inclination angles (α1,α2) and a second subsurface assessment parameter (b2) based on the first and third subsurface inclination angles (α1,α3). [2] Method according to claim 1, characterized by , that the first subsurface inclination angle (α1) is determined from the measured values ​​for the lateral acceleration (a m ), the yaw rate (ω m ) and the speed (v m ) is calculated. [3] Method according to any one of the preceding claims, characterized by , that the second substrate inclination angle (α2) is determined from the measured values ​​for the lateral acceleration (a m ) and for the speed (v m ) as well as from a first model quantity (M1), which is determined at least on the basis of the measured quantities for velocity (v m ), the lateral acceleration (a m ) and the steering angle (δ m ) is determined, is calculated. [4] Method according to any one of the preceding claims, characterized by , that the third subsurface inclination angle (α3) is derived from the measured values ​​for the yaw rate (ω) m ) and for the speed (v m ) as well as from a second model parameter (M2) which is determined at least on the basis of the measured parameters for velocity (v m ), the yaw rate (ω m ) and the steering angle (δ m ) is determined, is calculated. [5] Method according to any one of the preceding claims, characterized by , that the first subsurface inclination angle (α1) is determined using the inclination angle relationship sin(α)=ay−ωzvxg is determined, where the first subsurface inclination angle (α1) is used as the subsurface inclination angle α, and the lateral acceleration a is used as the lateral acceleration a. y the measured value for lateral acceleration (a m ), as yaw rate ω z the measured value for the yaw rate (ω) m ) and as velocity v x the measured value for speed (v m) is used. [6] Method according to any one of the preceding claims, characterized by , that the second subsurface inclination angle (α2) can be determined using the inclination angle relationship sin(α)=ay−ωzvxg is determined where the second subsurface inclination angle (α2) is used as the subsurface inclination angle α, and the lateral acceleration a is used as the lateral acceleration a. y the measured value for lateral acceleration (a m ), as velocity v x the measured value for speed (v m ) and as yaw rate ω z The first model size (M1) is used. [7] Method according to any one of the preceding claims, characterized by , that the third subsurface inclination angle (α3) can be determined using the inclination angle relationship sin(α)=ay−ωzvxg is determined where the third subsurface inclination angle (α3) is used as the subsurface inclination angle α, and the yaw rate ω is used as the yaw rate. z the measured value for the yaw rate (ω) m ), as velocity v xthe measured value for speed (v m ) and as lateral acceleration a y the second model size (M2) is used. [8] Method according to any one of the preceding claims, characterized by that the first model parameter is determined based on the relationship M1=vml(δm−lamvc2) is determined, where I is the axle spacing and v c the characteristic speed of the motor vehicle, and / or that the second model quantity (M2) is determined based on the relationship M2=vc2δml−vc2ωmvm is determined. [9] Method according to any one of the preceding claims, characterized by , that the first subsurface assessment parameter (b1) is used for yaw rate monitoring and the second subsurface assessment parameter (b2) is used for lateral acceleration monitoring, in particular to interrupt the respective monitoring in the presence of an inclined subsurface and / or to determine a permissible tolerance for the monitoring. [10] Driver assistance device (1) of a motor vehicle, in particular for carrying out the method according to one or more of the preceding claims, wherein the driver assistance device (1) is designed to perform the following steps: - Recording at least four measurements, in particular a lateral acceleration (a m ), a yaw rate (ω m ), a speed (v m ) and a steering angle (δ m ) of the motor vehicle, using at least one sensor device, - Calculating a first subsurface inclination angle (α1), a second subsurface inclination angle (α2) and a third subsurface inclination angle (α3), each from a subset of measurements consisting of a maximum of three of the recorded measurements (a m ,ω m ,v m ,δ m ) consists of which at most two of the measured values ​​(a m ,ω m ,v m ,δ m) are contained in one of the other measurement subsets, and - Determining a first subsurface assessment parameter (b1) based on the first and second subsurface inclination angles (α1,α2) and a second subsurface assessment parameter (b2) based on the first and third subsurface inclination angles (α1,α3).

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