Method and device for determining a transverse gradient of a road surface on which a two-wheeler travels

Abstract

A method for determining a transverse gradient of a road surface, on which a two-wheeler travels, the two-wheeler having at least one wheel, whose rolling circumference changes as a function of an inclination of the two-wheeler relative to the road surface, an inclination of the two-wheeler relative to the road surface being determined from a variable, which depends on the rolling circumference of the at least one wheel, and the transverse gradient of the road surface being determined from the tilt of the two-wheeler and the inclination relative to the road surface. A corresponding device and a computer program product are also described.

Claims

1. A method for controlling a two-wheeler on the basis of a transverse gradient of a road surface on which the two-wheeler travels, the method comprising: determining an inclination of the two-wheeler, the two-wheeler having only two wheels, each having a rolling circumference, the rolling circumference of at least one wheel of the two wheels changing as a function of an inclination of the two-wheeler relative to the road surface, relative to the road surface from a variable, which depends on the rolling circumference of the at least one wheel; determining a tilt of the two-wheeler; ascertaining the transverse gradient of the road surface from the tilt of the two-wheeler and the inclination of the two-wheeler relative to the road surface; and controlling, based on the ascertained transverse gradient, one of a braking system, a headlight control system, and a vehicle dynamics system of the two-wheeler.

2. The method of claim 1, wherein the inclination of the two-wheeler relative to the road surface is determined based at least partially on a comparison of the variable, which depends on the rolling circumference of the at least one wheel, with at least one reference value.

3. The method of claim 2, wherein the reference value is defined at least one of by using a learning function and by using at least one variable which describes the at least one wheel.

4. The method of claim 1, wherein at least one of the at least one wheel speed value and one variable, depending on the at least one wheel speed value, is used as the variable depending on the rolling circumference of the at least one wheel.

5. The method of claim 1, wherein the inclination of the two-wheeler relative to the road surface is determined from a variable depending on the rolling circumferences of the two wheels.

6. The method of claim 5, wherein the inclination of the two-wheeler relative to the road surface is determined from a speed difference of the two wheels.

7. The method of claim 1, wherein the tilt of the two-wheeler is determined with the aid of at least one tilt determination device.

8. The method of claim 7, wherein the at least one tilt determination device includes at least one of at least one acceleration sensor and at least one yaw rate sensor.

9. The method of claim 1, wherein the tilt is relative to a horizontal relative to a gravitational field of the earth.

10. A device for controlling a two-wheeler on the basis of a transverse gradient of a road surface on which the two-wheeler travels, comprising: an inclination determining arrangement to determine an inclination of the two-wheeler, the two-wheeler having only two wheels, each having a rolling circumference, the rolling circumference of at least one wheel of the two wheels changing as a function of an inclination of the two-wheeler relative to the road surface, relative to the road surface from a variable, which depends on the rolling circumference of the at least one wheel; a tilt determining arrangement to determine a tilt of the two-wheeler; a gradient ascertaining arrangement, in communication with the inclination determining arrangement and the tilt determining arrangement, to ascertain the transverse gradient of the road surface from the tilt of the two-wheeler and the inclination of the two-wheeler relative to the road surface; and an arrangement for controlling, based on the ascertained transverse gradient, one of a braking system, a headlight control system, and a vehicle dynamics system of the two-wheeler.

11. The device of claim 10, wherein the tilt is relative to a horizontal relative to a gravitational field of the earth.

12. A computer readable medium having a computer program, which is executable by a processor, comprising: a program code arrangement having program code for controlling a two-wheeler on the basis of a transverse gradient of a road surface on which the two-wheeler travels, the two-wheeler having two wheels, each having a rolling circumference, the rolling circumference of at least one wheel of the two wheels changing as a function of an inclination of the two-wheeler relative to the road surface, by performing the following: determining an inclination of the two-wheeler relative to the road surface from a variable, which depends on the rolling circumference of the at least one wheel; determining a tilt of the two-wheeler; ascertaining the transverse gradient of the road surface from the tilt of the two-wheeler and the inclination of the two-wheeler relative to the road surface; and controlling, based on the ascertained transverse gradient, one of a braking system, a headlight control system, and a vehicle dynamics system of the two-wheeler.

13. The computer readable medium of claim 12, wherein the tilt is relative to a horizontal relative to a gravitational field of the earth.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows in subfigures 1A through 1C a front wheel of a two-wheeler at different tilts, inclinations to the road surface and transverse gradients in a schematic diagram.

(2) FIG. 2 shows in subfigures 2A through 2C a rear wheel of a two-wheeler at different tilts, inclinations to the road surface and transverse gradients in a schematic diagram.

(3) FIG. 3 shows a method according to a particular specific embodiment of the present invention in the form of a block diagram.

(4) FIG. 4 shows a two-wheeler in which a method according to the present invention may be implemented.

DETAILED DESCRIPTION

(5) In subfigures 1A, 1B and 1C, FIG. 1 shows a front wheel 11 of a two-wheeler 1 in cross section in a schematic diagram and denoted by reference numeral 11 on the whole. Tires 111 and a hub 112 of front wheel 11 are schematically illustrated. The road surface is denoted by reference numeral 2.

(6) A coordinate system 10 is shown to illustrate the position of front wheel 11 in space. An axis H of the coordinate system denotes the horizontal (based on the gravitational field of the earth), and axis V denotes the vertical. Axis X runs at a right angle to the plane of the paper and denotes, for example, a rolling direction of front wheel 11 and thus a direction of travel of a two-wheeler or the axis of the road. An axis of rotation A of front wheel 11 lies in the plane of the paper. An axis B runs perpendicularly to axis of rotation A and is inclined relative to vertical V, depending on the tilt of front wheel 11 and thus also that of the two-wheeler.

(7) Subfigure 1A illustrates a situation in which front wheel 11 and thus a corresponding two-wheeler is not inclined relative to road surface 2, and road surface 2 also has no transverse gradient. In other words, road surface 2 runs parallel to horizontal H, and front wheel 11 stands upright. Axis of rotation A also runs parallel to axis H, while axis B runs parallel to vertical V. A radius R.sub.11 denotes the rolling circumference of front wheel 11. The front wheel contacts road surface 2 at a point P.sub.R corresponding to radius R.sub.11.

(8) Subfigure 1B illustrates a situation in which road surface 2 no longer runs parallel to horizontal H. Road surface 2 is instead inclined at a transverse slope angle of 45 here (100%), which is illustrated exaggeratedly. However, in the situation depicted here, the two-wheeler and thus front wheel 11 do not have a tilt. It is as shown in subfigure 1A. Tire 111 now contacts the road surface at a point P.sub.11 to yield a rolling circumference r.sub.11. This is smaller than rolling circumference R.sub.11, as is apparent when subfigure 113 is viewed together with subfigure 1A.

(9) If, as was the case with a single wheel, such a smaller rolling circumference is already detected, for example, via a higher rolling speed but no tilt of two-wheeler 1 is simultaneously detected, it may be assumed that a transverse gradient of road surface 2 is present but not a tilt of two-wheeler 1.

(10) Subfigure 1C illustrates a different case. Here, front wheel 11 itself and thus the two-wheeler have a tilt, for example, a tilt of 45 to the vertical V. However, road surface 2 also has a transverse gradient of 45. Tire 111 therefore contacts road surface 2 at point P.sub.R, as in the situation depicted in subfigure 1A. Rolling circumference R.sub.11 of wheel 11 therefore corresponds to that of subfigure 1A. Since an analysis of a rolling circumference would not reveal any difference in comparison with subfigure 1A, in this case the transverse gradient of road surface 2 may be inferred only on the basis of a tilt detected by a tilt sensor.

(11) As mentioned previously, there may be intermediate situations between the situations depicted in subfigures 1A through 1C, in which the transverse gradient of road surface 2, however, may be calculated from the respective determined inclinations and tilts.

(12) In accordance with subfigures 1A through 1C of FIG. 1, comparable angles of inclination and tilts of a rear wheel 12 of a two-wheeler are shown in subfigures 2A through 2C. The tires of rear wheels 12 are denoted by reference numeral 121;

(13) a hub is denoted by reference numeral 122. Accordingly, reference notation R.sub.12 is assigned to a maximum rolling circumference and reference notation r.sub.12 is assigned to a smaller rolling circumference. As is also apparent here, there is a reduction in the rolling circumference at an inclination of two-wheeler 1 relative to the road surface (subfigure 2B).

(14) As shown by a combined view of FIGS. 1 and 2, however, the rolling circumferences of front wheel 11 and of rear wheel 12 change to different extents at the same inclination (cf. subfigures 1B and 2B) because front wheel 11 and rear wheel 12 have different tire cross sections. The reduced rolling circumference of front wheel r.sub.11 is therefore still greater than the reduced rolling circumference of rear wheel r.sub.12.

(15) At the same inclination relative to road surface 2, front and rear wheels 11, 12 contact road surface 2, i.e., at different positions P.sub.11 and P.sub.12. This results in different rolling circumferences r.sub.11 and r.sub.12, but rolling circumferences P.sub.R are the same. It is apparent from this that, in the absence of an inclination to road surface 2 of two-wheeler 1, no speed difference is observable between front wheel 11 and rear wheel 12. However, there is a speed difference when a corresponding inclination is present. This difference may be used according to the present invention to determine an inclination.

(16) FIG. 3 schematically shows a method according to a particular specific embodiment of the present invention which is denoted by reference numeral 100 on the whole. This method has three main method steps 101, 102 and 103.

(17) In a first method step 101, an inclination of two-wheeler 1 relative to a road surface 2 is determined, namely from the rolling circumferences and/or values depending thereon, as explained.

(18) In a step 102, a tilt of two-wheeler 1 is determined. As explained, this takes place by using suitable tilt sensors, for example.

(19) In a step 103, the transverse gradient of road surface 2 is ascertained from the inclination and the tilt.

(20) FIG. 4 shows a two-wheeler 1, which is ridden by a rider 3 on a road surface 2. Coordinate system 10 and axes A and B correspond to those of FIGS. 1 and 2. Two-wheeler 1 is shown in a view from the rear, so that only rear wheel 12 is discernible.

(21) Two-wheeler 1 has a tilt determination device 13, for example, having at least one acceleration sensor and/or at least one yaw rate sensor.

(22) Road surface 2 in the diagram of FIG. 5 does not have a transverse gradient but two-wheeler 1 with its rear wheel 12 is in a tilt relative to vertical V, as may be determined by tilt determination device 13.