Method and device for determining the inclined position of a vehicle

Abstract

A method for determining the inclined position, includes using a sensor, whose measuring axis is inclined by a pitch angle with respect to the longitudinal axis of the vehicle, a rate of rotation having a roll rate component and a yaw rate component is measured. Ultimately, a roll angle for describing the inclined position of the vehicle is ascertained from the rate of rotation.

Claims

1. A method for determining an inclined position of a vehicle, the method comprising: measuring, with the aid of a sensor, whose measuring axis is inclined by a fixed pitch angle with respect to a longitudinal axis of the vehicle, a rate of rotation of the vehicle, which has a roll rate component and a yaw rate component; and ascertaining a roll angle of the vehicle from the rate of rotation.

2. The method of claim 1, wherein the yaw rate of the vehicle is calculated, using a yaw rate model, and the roll rate is ascertained from the measured rate of rotation as a function of the calculated yaw rate.

3. The method of claim 2, wherein the yaw rate model includes a dependence on the longitudinal speed of the vehicle.

4. The method of claim 2, wherein the yaw rate model includes a dependence on the transverse acceleration of the vehicle.

5. The method of claim 1, wherein the rate of rotation about a measuring axis, which does not point in a direction of the longitudinal axis or the vertical axis of the vehicle, is measured.

6. The method of claim 1, wherein an initial value for the roll angle is selected, and the roll angle is ascertained in an iterative process.

7. The method of claim 1, wherein a piece of information regarding the position of the roadway and/or the pitch angle of the vehicle is considered in the determination of the roll angle.

8. The method of claim 7, wherein a piece of information regarding the position of at least one of the roadway and the pitch angle of the vehicle is ascertained from a signal of at least one of at least one acceleration sensor and at least one wheel speed sensor.

9. The method of claim 1, wherein a piece of information regarding the change in position of the roadway and/or in the pitch angle of the vehicle is considered in the determination of the roll angle.

10. The method of claim 9, wherein a piece of information regarding the change in at least one of the position of the roadway and the pitch angle of the vehicle is ascertained from a signal of at least one rotation rate sensor.

11. The method of claim 1, wherein it is used for determining the inclined position of a two-wheeled vehicle.

12. A processing unit for determining an inclined position of a vehicle, comprising: a measuring arrangement to measure, with the aid of a sensor, whose measuring axis is inclined by a fixed pitch angle with respect to a longitudinal axis of the vehicle, a rate of rotation of the vehicle, which has a roll rate component and a yaw rate component; and an ascertaining arrangement to ascertain a roll angle of the vehicle from the rate of rotation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic block diagram of a specific embodiment of a method for determining the inclined position of a vehicle.

(2) FIG. 2 shows a possible orientation of a sensor for measuring a rate of rotation having a roll-rate and a yaw-rate component.

DETAILED DESCRIPTION

(3) FIG. 1 shows a schematic block diagram of a specific embodiment of a method for determining the inclined position of a vehicle, such as a motorcycle, which is not shown in further detail.

(4) In a first step S1, a rate of rotation is measured by a rotation rate sensor 1, as is shown in FIG. 2. Rotation rate sensor 1 may be, e.g., a piezoelectric or a micromechanical sensor.

(5) Measuring axis 2 of sensor 1 lies in an xz plane of the vehicle coordinate system, x direction 3 being determined by the longitudinal axis and z direction 4 being determined by the vertical axis of the motorcycle. Thus, the sensor measures both a roll rate component and a yaw rate component, but not a pitch rate component. In the orientation shown, measuring signal of rotation rate sensor 1 is expressed by the formula:
=W cos()G sin (1)
where W is the roll rate W and G is the yaw rate G of the vehicle. In this case, angle is the angle formed by measuring axis 2 and x axis 3. It is also situated in the xz plane of the vehicle coordinate system, and it may be approximately 45. As an alternative, the measuring axis may also be situated in the opposite quadrant, at an angle of approximately 225.

(6) In step S2, yaw rate G of the vehicle is calculated using a yaw rate model, which includes a dependence on roll angle . For example, the following model may be used for this:
G=(ayg sin(.sub.n))/v(2)

(7) In this context, the variables ay and v are the transverse acceleration and the longitudinal speed of the vehicle. The variables mentioned may be measured by sensors in a known manner or determined in another way. In the case of a motorcycle, transverse acceleration ay is usually small, and in most driving situations, it may be set to the value of zero as an approximation. In this case, only longitudinal speed v has to be ascertained. In the first iteration step, an arbitrary initial value between 90 and 90, which may be 0, may be selected as angle .sub.n.

(8) In a third step S3, the yaw rate G calculated from equation (2) on the basis of a model is inserted into equation (1), and roll rate W is solved for. The following equation results from this:

(9) $\begin{array}{cc}W=W\left(\right)=\frac{v\tan \left(\right)\left(\mathrm{ay}-g\sin \left(\right)\right)}{v}+/\cos \left(\right)& \left(4\right)\end{array}$

(10) Therefore, a roll rate is ascertained as a function of roll angle .

(11) The roll angle may ultimately be calculated in an iterative process:
.sub.n+1=.sub.n+W(.sub.n)dt(3)

(12) When new roll angle .sub.n+1 is calculated in step S3, then the method returns to step S1, and a rate of rotation is measured, with the aid of which the next iteration step is carried out. However, the roll angle last calculated in step S3 is used in step S2 (.sub.n=.sub.n+1).

(13) After several iteration steps, the roll angle is independent of initial value .sub.0. This is a consequence of the fact that W() includes a negative term dependent on (see equation (4)). Consequently, the method is stable in the long term.

(14) In addition to above-described steps S1 through S3, a further step S4 may also be executed. In step S4, the inclination of the roadway and/or the pitch angle and/or the pitch rate are ascertained. This may be accomplished, for example, using a position sensor, additional acceleration sensors and/or rotation rate sensors.

(15) The above-mentioned variables may be taken into account in the calculation of the roll rate in step S2, or in the determination of the roll angle in step S3, and the roll angle may be correspondingly corrected. Therefore, the inclined position of the motorcycle may be determined more accurately.