Method For Determining The Speed of A Motor Vehicle

• US 20090265073A1
• Filed: 05/21/2009
• Published: 10/22/2009
• Est. Priority Date: 11/30/2006
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Kagerer, Walter, Meske, Alexander, Langer, Falk, Laiou, Maria-Christina
• Granted Patent: US 7,970,525 B2
• Time in Patent Office: Days
• US Class Current: 701/93
• CPC Class Codes: B60W 40/105 Speed
• CPC Class Codes: G01P 13/00 Indicating or recording presence, absence, or direction, of movement electric switches H01H; counting moving objects G06M7/00
• CPC Class Codes: G01P 3/56 for comparing two speeds

Abstract

The invention relates to a method for determining the vehicle speed of a motor vehicle, wherein a provisional first speed value is determined for high speeds and a provisional second speed value is determined for low speeds and the vehicle speed is determined as a function of the determined provisional first speed value either from the provisional first speed value or from the provisional second speed value, or from a combination of the first and second speed values.

Claims

1. A method for determining a vehicle speed of a motor vehicle through a control device, comprising the steps of:

determining a provisional first speed value for high speeds and a provisional second speed value for low speeds; and

determining the vehicle speed as a function of the determined provisional first speed value either from the provisional first speed value or from the provisional second speed value or from a combination of the first and second speed values.

2. The method according to claim 1, wherein the vehicle speed is determined from the provisional second speed value, such that the vehicle speed corresponds to the provisional second speed value when the determined provisional first speed value falls below a predetermined first threshold.

3. The method according to claim 1, wherein the vehicle speed is determined from the provisional first speed value, such that the vehicle speed corresponds to the provisional first speed value when the determined provisional first speed value exceeds a predetermined second threshold.

4. The method according to claim 2, wherein the vehicle speed is determined from the provisional first speed value such that the vehicle speed corresponds to the provisional first speed value when the determined provisional first speed value exceeds a predetermined second threshold.

5. The method according to claim 1, wherein the vehicle speed is determined from a combination of the first and second speed values such that the vehicle speed is a weighted total of the provisional first and second speed values, the weighting of the total being dependent on the provisional first speed value and the weighting factors amounting to one in total, when the determined provisional first speed value exceeds a predetermined first threshold and falls below a predetermined second threshold.

6. The method according to claim 5, wherein the provisional first speed value is determined such that that it assumes the value zero if no clear driving direction of the vehicle is detected and/or if a standstill state is detected.

7. The method according to claim 6, wherein the provisional first speed value is determined such that it assumes the negative value of a speed value which is becoming non-negative if it does not assume the value zero and if it is clearly detected that the vehicle is moving backwards.

8. The method according to claim 6, wherein the provisional first speed value is determined such that it assumes the value of the non-negative speed value if it does not assume the value zero or the negative value of the non-negative speed value.

9. The method according to claim 7, wherein the provisional first speed value is determined such that it assumes the value of the non-negative speed value if it does not assume the value zero or the negative value of the non-negative speed value.

10. The method according to claim 7, wherein the non-negative speed value is determined such that it corresponds to the average wheel speed of the non-powered wheels independently of the direction of rotation of the wheels, if the average exceeds a predetermined positive average threshold and otherwise is zero.

11. The method according to claim 8, wherein the non-negative speed value is determined such that it corresponds to the average wheel speed of the non-powered wheels independently of the direction of rotation of the wheels, if the average exceeds a predetermined positive average threshold and otherwise is zero.

12. The method according to claim 9, wherein the non-negative speed value is determined such that it corresponds to the average wheel speed of the non-powered wheels independently of the direction of rotation of the wheels, if the average exceeds a predetermined positive average threshold and otherwise is zero.

13. The method according to claim 1, wherein the provisional second speed value is determined such that it either corresponds to the average of all the actual wheel speeds if none of the determined actual wheel speeds is negative and otherwise is determined as a function of the total of the negative wheel speeds.

14. The method according to claim 12, wherein the provisional second speed value is determined such that it either corresponds to the average of all the actual wheel speeds if none of the determined actual wheel speeds is negative and otherwise is determined as a function of the total of the negative wheel speeds.