DE10327695A1 - Vehicle state determination method in which yaw and side slip angles are determined from the vehicle's angle relative to lane markings or road edge and its distance to the markings or edge - Google Patents

Abstract

The slip and yaw angles of the vehicle (10) as well as the rate of change of the angle between its longitudinal axis and a reference object are determined as vehicle characteristics and are determined from the following geometric data: the angle between its longitudinal axis and a reference object and the distance to the reference object. An independent claim is made for a device for determining the driving condition of a motor vehicle. Traffic lane markings are suitable for use as reference markings.

Description

The The invention relates to a method for determining a driving condition of a vehicle characterizing size, in particular the slip angle, according to the generic term of claim 1, and a corresponding device according to the preamble of claim 8.

Vehicle dynamics control, such as. ESP (electronic stability program), regulate the driving behavior of a vehicle in the dynamic driving limit and ensure the controllability of the vehicle in critical situations. For this purpose, it must be determined how the vehicle is in the border area should behave according to the driver's request (target behavior) and as it is in fact behaves (actual behavior). Essential variables are while the slip angle and the yaw rate of the vehicle. The slip angle is usually model-based, i.e. based on a mathematical model, depending of further state variables of the Vehicle determined. This is especially in the dynamic driving limit area relatively inaccurate, since the models used in this area their validity to lose.

Further it is known, the slip angle using special sensors, such as. Radar or optical sensors, to measure the vectorial vehicle speed over ground determine. However, such systems are relatively expensive and therefore not to be expected in production vehicles for the foreseeable future.

It Therefore, the object of the present invention is a device and to provide a method by which the driving condition of a Vehicle characterizing size, in particular the slip angle β, accurate and inexpensive be determined using a sensor available in the vehicle can.

Is solved this task according to the invention by the specified in claim 1 and in claim 8 Characteristics. Further embodiments The invention are the subject of subclaims.

Of the essential idea of the invention is the vehicle position in terms of a reference object, e.g. relative to the roadside, with the help a sensor to detect, from the sensor signals geometric Data, such as the distance or orientation of the vehicle, to determine, and the driving condition characterizing size of the to calculate geometric data. This has the advantage that the the driving condition characterizing size simply by geometric considerations and can be calculated exactly. Model assumptions do not have to to be hit.

Vehicle sizes that can be calculated with this method are, in particular, the slip angle and the yaw rate of the vehicle, as well as the wheel slip angle. The slip angle may e.g. solely from the vehicle's longitudinal speed, the distance and its time derivative to the reference object and the angle between the vehicle's longitudinal axis and reference object are determined.

The Sensor system preferably comprises a video system whose video signals from video signal processing (e.g., software) become. The video signal processing software provides as a geometric Data preferably the distance of the vehicle to the roadside and an orientation angle, in particular the angle between the vehicle longitudinal axis and roadside. Optionally, could also another type of sensor, such as Magnetic sensors in conjunction with magnets integrated in the roadway, can be used to to determine the geometric data.

to Determining the float angle is preferably the distance of the Vehicle determined to the reference object and from the change of the distance calculates a first vehicle speed. Further is preferably a second vehicle speed in a second Direction determined. The slip angle may eventually turn off the two speeds are calculated.

Optional can also be the yaw rate of the vehicle from the geometric data be determined. The yaw rate results for example from the temporal change the angle between the vehicle's longitudinal axis and reference object and the road curvature. The road curvature can e.g. also be provided by the sensor. Such a determined Yaw rate could e.g. for monitoring the yaw rate sensor of a vehicle dynamics control system can be used.

According to one another embodiment The invention can be calculated from the measured geometrical data e.g. also the slip angle for the Wheels of the Front or rear axle to be determined.

The Invention will be exemplified below with reference to the accompanying drawings explained in more detail. It demonstrate:

1 a schematic representation of a system for determining a driving condition characterizing size by lane detection;

2 the coordinate system and the measured quantities for the calculation of the driving condition characterizing size; and

3 an enlarged view of the vehicle with the sizes required for the Schwimmwinkelberechnung.

1 shows a system for determining a driving condition of the vehicle characterizing size, such as the slip angle β or the slip angle α. The system includes a sensor for this purpose 1 , In the present example, a vehicle-mounted video surveillance device 1 that the roadside 11 (please refer 2 ). The video signals 5 are from a video signal processing device 3 (eg a software), the resulting distance Y _{d of} the camera to the roadside 11 and the angle ψ _d between the roadside 11 and vehicle longitudinal axis (direction of v _x , 2 ). A computing device 4 finally calculates from the geometric data Y _d , ψ _d the slip angle β or the slip angle α. Unless of the sensors 1 If the radius of curvature of the roadway is also provided, the yaw rate dψ / dt can also be determined. The algorithm for calculating the driving condition characterizing size does not make any model assumptions, so that the driving condition descriptive size can also be determined correctly in the driving dynamics border area.

The video signal processing device 3 and the computing device 4 are as software modules in a control unit 2 deposited.

To determine the slip angle β, only the vehicle longitudinal speed v _x , the distance Y _d to the roadway edge 11 or whose time derivative and the angle ψ _d between the vehicle longitudinal axis and the edge of the roadway required. Next to the video system 1 for environment detection and a sensor for determining the vehicle longitudinal speed v _x no further sensor is required.

1. Calculation of the slip angle β

A method for determining the slip angle is described below with reference to 2 exemplified in more detail. 2 shows a vehicle 10 with the essential, for the determination of the slip angle required sizes. The video signal processing software 3 provides a distance Y _{d of} the vehicle 10 to the roadside 11 and the angle ψ _d between the roadside 11 and vehicle longitudinal axis (direction of v _x ). These quantities are determined in the lane boundary coordinate system (x _B , y _B ), whose x-axis is tangent to the lane edge, and whose y-axis is determined by a reference point in the vehicle 10 , eg the center of mass, runs.

wobei T_s die Abtastzeit des Systems und k den Index des aktuellen Zeitpunkts bezeichnet. Im Folgenden wird das Zeitargument kT_s zu Gunsten der Lesbarkeit weggelassen, da stets der aktuelle Zeitpunkt kT_s betrachtet wird.To determine the _slip angle β, a velocity component v _{yB of} the vehicle speed v in the _{lane boundary} coordinate system is first determined. This can be done, for example, by numerically differentiating the distance Y _d , where:

where T _{s is} the sampling time of the system and k is the index of the current time. In the following, the time argument kT _{s is} omitted in favor of readability, since the current time kT _s is always considered.

In a next step, the speed component v _{xB of} the vehicle speed v in the roadway coordinate system is calculated. For this purpose, first the length l ₁ (see 3 ), for which in the right-angled triangle ABC:

For the vehicle longitudinal velocity v _x , the reference velocity determined in the vehicle dynamics control system (ESP) is assumed here. The angle ψ _d , as mentioned, from the video signal processing device 3 delivered.

In the following the length l _{2 is} calculated. Since the angle ψ _{d is} also found in the right-angled triangle CDE, and v _{yB has} already been calculated, the length l ₂ applies: l 2 = tan (ψ d v yB

The velocity component v _xB in the lane _boundary coordinate system results from the difference between l ₁ and l ₂ to: v xB = l 1 - l 2

So both are speed components of the vehicle 10 in the lane boundary coordinate system, and the heading angle θ can be calculated:

The wanted slip angle β is the difference between the angle ψ _d and the course angle θ: β = ψ d - θ

It is possible, the slip angle β pure due to geometric considerations to calculate.

The quality of the calculation depends strongly on the quality of the input variables, in particular on the quantity Y _d . Noise occurring in the conventional measuring methods can be compensated if, instead of the simple difference quotient, a more accurate method, such as a higher-order difference quotient or equalization _polynomial , is used by several values of Y _d to calculate the lateral _velocity v _yB (kT _s ).

2. Calculation of yaw rate dψ / dt.

berechnet werden kann. Die „Giergeschwindigkeit des Fahrbahnrandes" ist näherungsweise: dψB/dt = κ·vxB. Used by the video sensors 1 also the curvature κ of the roadside 11 measured, the yaw rate dψ / dt of the vehicle can be determined. For the yaw rate dψ / dt applies: dψ / dt = dψ d / dt + dψ B / Dt, wherein the temporal change of the difference angle ψ _d, for example by means of the difference quotient

can be calculated. The "yaw rate of the roadside" is approximately: dψ B / dt = κ · v xB ,

A thus determined yaw rate dψ / dt could for example for monitoring a yaw rate sensor of a vehicle dynamics control system (ESP) used become.

3. Calculation the skew angle α

With knowledge of the slip angle β and the yaw rate dψ / dt can be determined taking into account the steering angle δ and the slip angle at the wheels of the front and rear axles. The steering angle δ can be measured, for example, by means of the ESP sensor. The following relationships apply to the slip angles of the wheels on the front axle α _v and rear axle α _h :

The yaw rate dψ / dt can be determined here either by means of a yaw rate sensor or, as described above, by calculation. The thus determined slip angle α _v , α _h can be supplied to a vehicle dynamics control system for further use.

1

sensors

2

control unit

3

processing device

4

computing device

5

sensor signals

10

vehicle

11

kerbside

Y _d

distance Vehicle Underlying

_d

angle Vehicle longitudinal axis reference object

β

float angle

α

Slip angle

v _x

Vehicle longitudinal speed

θ

course angle

x _B , y _B

Lane edge coordinates

κ

road curvature

Claims (8)

Method for determining a driving condition of a vehicle ( 10 ) characterizing quantity (β, dψ / dt, α), in which the vehicle position with respect to a reference object ( 11 ) by means of a sensor system ( 1 ) and geometric data (ψ _d , Y _d ) from the sensor signals ( 5 ), which determine the relative position of the vehicle ( 10 ), characterized in that the variable characterizing the driving condition (β, dψ / dt, α) is determined from the geometric data (ψ _d , Y _d ). Method according to Claim 1, characterized in that a distance (Y _d ) of the vehicle ( 10 ) to the reference object ( 11 ) and from the change of the distance a vehicle _speed (v _yB ) in a first direction is calculated. A method according to claim 2, characterized in that a vehicle _speed (v _xB ) is determined in a second direction. Method according to one of the preceding claims, characterized in that the sensor system ( 1 ) comprises a video system whose signals are received from an evaluation unit ( 3 ) be evaluated. Method according to one of the preceding claims, characterized in that the slip angle (β) of the vehicle ( 10 ) from the vehicle longitudinal speed (v _x ), the distance (Y _d ) to the reference object ( 11 ) and the angle (ψ _d ) between the vehicle longitudinal axis and the reference object ( 11 ) is calculated. Method according to one of the preceding claims, characterized in that the yaw rate (dψ / dt) from the geometric data (ψ _d , Y _d ) and the road curvature κ is calculated. Method according to one of the preceding claims, characterized in that the skew angle (α) _is calculated from the geometric data (ψ _d , Y _d ). Device for determining the driving state of the vehicle ( 10 ) characteristic size (β, dψ / dt, α), with a sensor system ( 1 ) for detecting the vehicle position with respect to a reference object ( 11 ) and an evaluation unit ( 3 ) for determining geometric data (ψ _d , Y _d ) from the sensor signals ( 5 ), characterized by a computing device ( 2 ), which is set up in such a way that the variable (β, dψ / dt, α) characterizing the driving state is determined from the geometric data (ψ _d , Y _d ).