Method and device for determining a force exercised by the ground on a wheel

• US 20050212356A1
• Filed: 01/28/2005
• Published: 09/29/2005
• Est. Priority Date: 07/31/2002
• Status: Active Grant

• Current Assignee: Compagnie générale des établissements Michelin
• Original Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA), Societe De Technologie Michelin (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Huchard, Xavier, Lenoir, Jean-Yves
• Granted Patent: US 7,055,917 B2
• Time in Patent Office: Days
• US Class Current: 303/112
• CPC Class Codes: B60G 17/0195 characterised by the regulation being combined with other vehicle control systems conjoint control of vehicle sub-units including control of suspension systems B60W10/22
• CPC Class Codes: B60G 2200/142 with a single lateral arm, e.g. MacPherson type
• CPC Class Codes: B60G 2202/312 The spring being a wound spring
• CPC Class Codes: B60G 2204/11 Mounting of sensors thereon
• CPC Class Codes: B60G 2204/113 Tyre related sensors
• CPC Class Codes: B60G 2204/143 on the vehicle body or chassis
• CPC Class Codes: B60G 2400/64 Wheel forces, e.g. on hub, spindle or bearing
• CPC Class Codes: B60G 2600/1878 Neural Networks
• CPC Class Codes: B60G 2600/1879 Fuzzy Logic Control
• CPC Class Codes: B60G 2800/215 by applying a braking action on each wheel individually
• CPC Class Codes: B60G 2800/22 Braking, stopping
• CPC Class Codes: B60G 2800/702 Improving accuracy of a sensor signal
• CPC Class Codes: B60G 2800/92 ABS - Brake Control
• CPC Class Codes: B60G 2800/94 Electronic Stability Program (ESP, i.e. ABS+ASC+EMS)
• CPC Class Codes: B60T 13/74 with electrical assistance or drive
• CPC Class Codes: B60T 8/174 characterised by using special control logic, e.g. fuzzy logic , neural computing

Abstract

A device and method are provided for determining a longitudinal force (Fx) exerted on a wheel of a motor vehicle by a ground surface supporting the wheel, the vehicle including connections means which connect the wheel to a body of the vehicle. An actual force (FAX) is measured at the level of at least one measurement point in the connection means. A force (FDx, Fx) is calculated which results from a transmission via the connection means from the at least one measurement point to the wheel, of a body-associated force (FADX, FAX), which depends at least on the actual force. The longitudinal force (Fx) exerted on the wheel by the ground surface is calculated as a function at least of the force (FDx; Fx) resulting from the transmission of the body-associated force.

Claims

1. A method for determining a longitudinal force (Fx) exerted on a wheel of a motor vehicle by a ground surface supporting the wheel, the vehicle comprising connections means which connect the wheel to a body of the vehicle, the method comprising:

measuring an actual force (FAX) at a level of at least one measurement point in the connection means,

calculating a force (FDx, Fx) resulting from a transmission via the connection means from the at least one measurement point to the wheel, of a body-associated force (FADX, FAX), which depends at least on the actual force,

calculating the longitudinal force (Fx) exerted on the wheel by the ground surface as a function at least of the force (FDx;

Fx) resulting from the transmission of the body-associated force.

2. The method according to claim 1, wherein the force (FDx;

Fx) resulting from the transmission of the body-associated force is calculated as a function of at least one parameter chosen from among;

a steering angle (α

) of the wheel, a vertical distance (z) of the wheel relative to the body, an activity condition of a braking system coupled to the wheel, and a drive torque (Γ

) applied to the wheel by an engine of the vehicle.

3. The method according to claim 2, further comprising:

measuring the steering angle (α

) of the wheel, and

calculating the force (FDx;

Fx) resulting from transmission of the body-associated force as a function of the steering angle.

4. The method according claim 2, further comprising:

measuring the vertical distance (z) of the wheel relative to the body is measured, and

calculating the force (FDx;

Fx) resulting from transmission of the body-associated force as a function of the vertical distance.

5. The method according to claim 2, further comprising:

detecting the activity condition (L) of the braking system coupled to the wheel, and

calculating the force (FDx;

Fx) resulting from transmission of the body-associated force as a function of the detected activity condition.

6. The method according to any of claims 1 to 5, wherein the force (FDx;

Fx) resulting from the transmission of the body-associated force is calculated by applying to the body-associated force (FADX;

FAX) a transfer function representative of the connection means.

7. The method according to claim 6, wherein the transfer function is applied by means of at least one neuronal network.

8. The method according to claim 2, wherein the wheel is a driving wheel and the method further comprises:

measuring the drive torque (Γ

) applied to the wheel by the engine of the vehicle, and

calculating the force (FDx;

Fx) resulting from transmission of the body-associated force as a function of the drive torque (Γ

).

9. The method according to any of claims 1 to 5, wherein the body-associated force consists of the actual force (FAX).

10. The method according to claim 8, further comprising calculating a virtual, wheel-associated driving force (FMx), which represents a reaction of the ground surface to the drive torque, wherein:

the body-associated force (FADX) depends on the virtual wheel-associated driving force (FMx),

the force resulting from transmission of the body-associated force is calculated as a virtual, wheel-associated resistance force (FDx), and

the longitudinal force (Fx) exerted on the wheel by the ground surface is calculated as a function of the virtual, wheel-associated driving force (FMx) and of the virtual, wheel-associated resistance force (FDx).

11. The method according to claim 10, wherein the calculation of the body-associated force (FADX) comprises:

calculating a virtual, body-associated driving force (FAMX), which would result from a transmission of the virtual, wheel-associated driving force (FMx) from the wheel to the at least one measurement point via the connection means, and

calculating the body-associated force as a virtual, body-associated resistance force (FADX), as a function of the actual force (FAX) and of the virtual, body-associated driving force (FAMX), the virtual, body-associated resistance force being applied at the level of the at least one measuring point.

12. The method according to any of claims 1 to 5, wherein the at least one measuring point comprises a connection point between the connection means and the body, and the actual force (FAX) measured is a force exerted on the body at the level of the connection point.

13. The method according to claim 12, wherein the connection means comprises a hub support on which the wheel is mounted, a suspension wishbone or arm connected to the hub support, and at least one elastic joint comprising two mountings connected by an elastic body, a first of the mountings being fixed to the suspension wishbone, and a second of the mountings being fixed to the body and constituting the at least one connection point to the body.

14. The method according to claim 13, wherein the actual force (FAX) is measured by determining a deformation of the elastic body.

15. The method according to any of claims 1 to 5, wherein the actual force (FAX) is measured parallel to a longitudinal direction of the vehicle.

16. A device for determining a longitudinal force (Fx) exerted on a wheel of a motor vehicle by a ground surface supporting the wheel, the vehicle comprising connection means that connect the wheel to a body of the vehicle, the device comprising:

means for measuring an actual force (FAX) at a level of at least one measurement point in the connection means,

means for calculating a force (FDx;

Fx) that results from a transmission via the connection means, from the at least one measurement point to the wheel, of a body-associated force (FADX;

FAX) that depends at least on the actual force (FAX), and

means for calculating the longitudinal force (Fx) exerted on the wheel by the ground surface as a function at least of the force (FDx;

Fx) resulting from the transmission of the body-associated force.

17. The device according to claim 16, further comprising means for measuring a steering angle (α

) of the wheel, wherein the force (FDx;

Fx) resulting from the transmission of the body-associated force is calculated as a function of the steering angle.

18. The device according to claim 16, further comprising means for measuring a vertical distance (z) of the wheel relative to the body, wherein the force (FDx;

Fx) resulting from the transmission of the body-associated force is calculated as a function of the vertical distance.

19. The device according to claim 16, further comprising means for detecting an activity condition (L) of a braking system coupled to the wheel, wherein the force (FDx;

Fx) resulting from the transmission of the body-associated force is calculated as a function of the activity condition.

20. The device according to claim 16, further comprising means for measuring a drive torque (Γ

) applied to the wheel by an engine of the vehicle, wherein the force (FDx;

Fx) resulting from transmission is calculated as a function of the drive torque (Γ

).

21. The device according to claim 20, further comprising:

means for calculating a virtual, wheel-associated driving force (FMx) that represents a reaction of the ground surface to the driving torque (Γ

),

means for calculating a virtual, body-associated driving force (FAMX) that would result from transmission of the virtual wheel-associated driving force (FMx) from the wheel to the at least one measurement point via the connection means,

means for calculating the body-associated force as a virtual, body-associated resistance force (FADX), as a function of the actual force (FAX) and of the virtual, body-associated driving force (FAMX), the virtual, body-associated resistance force (FADX) being applied at the level of the at least one measurement point,

wherein the force resulting from transmission of the body-associated force is calculated as a virtual, wheel-associated resistance force (FDx), and the longitudinal force (Fx) exerted on the wheel by the ground surface is calculated as a function of the virtual, wheel-associated driving force (FMx) and of the virtual, wheel-associated resistance force (FDx).