Method for Controlling Vehicle Dynamics

• US 20100114431A1
• Filed: 10/31/2008
• Published: 05/06/2010
• Est. Priority Date: 10/31/2008
• Status: Abandoned Application

• Current Assignee: Volkswagen Group Of America Incorporated (Volkswagen AG)
• Original Assignee: Volkswagen Group Of America Incorporated (Volkswagen AG)
• Inventors: Switkes, Joshua, Stoschek, Arne
• Application Number:
  US12/262,702
• Publication Number:
  US 20100114431A1
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B60T 2201/08 Lane monitoring; Lane Keeping Systems
• CPC Class Codes: B60T 2201/083 using active brake actuation
• CPC Class Codes: B60T 2201/087 using active steering actuation
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 2260/04 Automatic transmission
• CPC Class Codes: B60T 2260/06 Active Suspension System
• CPC Class Codes: B60T 8/17557 specially adapted for lane departure prevention road vehicle drive control systems for lane keeping otherwise than by controlling a particular sub-unit B60W30/12
• CPC Class Codes: B62D 15/025 Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation B62D1/28 takes precedence
• CPC Class Codes: B62D 6/003 in order to control vehicle yaw movement, i.e. around a vertical axis B62D6/007 takes precedence
• CPC Class Codes: B62D 6/006 using a measured or estimated road friction coefficient

Abstract

A method for controlling vehicle dynamics includes acquiring steering torque data indicative of forces acting on at least one tire of a vehicle and acquiring image data by capturing images of an area outside the vehicle. The friction coefficient between a tire of the vehicle and a road surface is determined as a function of vehicle data including at least the steering torque data. The lateral velocity of the vehicle is determined as a function of vehicle data including the steering torque data and/or the image data. A vehicle dynamics control is performed as a function of the lateral velocity and the friction coefficient.

Claims

1. A method for controlling vehicle dynamics, which comprises:

acquiring steering torque data indicative of forces acting on at least one tire of a vehicle;

acquiring image data by capturing images of an area outside the vehicle;

determining a friction coefficient between at least one tire of the vehicle and a road surface as a function of vehicle data including at least the steering torque data;

determining a lateral velocity of the vehicle as a function of vehicle data including at least one of the steering torque data and the image data; and

performing a vehicle dynamics control as a function of at least the lateral velocity and the friction coefficient.

2. The method according to claim 1, which comprises:

acquiring the image data with a vehicle-mounted camera by capturing images of a road;

performing an image processing in order to detect lane markers provided on the road; and

determining the lateral velocity of the vehicle by evaluating a motion of the vehicle with respect to the lane markers.

3. The method according to claim 2, which comprises:

determining a lateral error of the vehicle by evaluating a motion of the vehicle with respect to the lane markers, wherein the lateral error is a distance between an imaginary lane centerline and a center of gravity of the vehicle;

determining a heading error of the vehicle by evaluating the motion of the vehicle with respect to the lane markers, wherein the heading error is a difference in angle between the imaginary lane centerline and a direction of a longitudinal axis of the vehicle;

determining a longitudinal velocity of the vehicle; and

determining the lateral velocity of the vehicle as a function of the lateral error, the heading error and the longitudinal velocity the vehicle.

4. The method according to claim 1, which comprises determining at least the lateral velocity of the vehicle with an optic flow technique by examining an apparent movement of objects in images captured by a camera and by calculating a motion of the vehicle as a function of the apparent movement of the objects in the images.

5. The method according to claim 1, which comprises using a vehicle-mounted rear-view camera in order to capture the images of the area outside the vehicle.

6. The method according to claim 1, which comprises acquiring the steering torque data by measuring a torque with a torque sensor mounted in a steering column of the vehicle.

7. The method according to claim 1, which comprises acquiring the steering torque data from torque measurements performed by a sensor measuring a torque across a power steering unit of one of an electric power steering system and a steer-by-wire steering system.

8. The method according to claim 1, which comprises acquiring the steering torque data by evaluating a torque provided by an electric motor powering an electric power steering system of the vehicle.

9. The method according to claim 1, which comprises acquiring the steering torque data by measuring a force in a steering tie-rod of a steering system of the vehicle.

10. The method according to claim 1, which comprises acquiring the steering torque data by measuring, with a sensor integrated in a tire of the vehicle, a force acting on the tire of the vehicle.

11. The method according to claim 1, which comprises:

determining a body sideslip angle of the vehicle;

performing a vehicle dynamics control by engaging a vehicle dynamics control system, if at least one of the lateral velocity and the body sideslip angle exceeds a respective threshold value; and

controlling, with the vehicle dynamics control system, at least one vehicle system selected from the group consisting of a brake system, a steering system, an engine, a transmission and a suspension system.

12. The method according to claim 1, which comprises:

determining wheel slip angles as a function of the lateral velocity of the vehicle, a longitudinal velocity of the vehicle, a distance between a center of gravity of the vehicle and a front axle of the vehicle, a distance between the center of gravity of the vehicle and a rear axle of the vehicle, a yaw rate and a steering angle;

performing a vehicle dynamics control by engaging a vehicle dynamics control system, if at least one of the wheel slip angles exceeds a respective threshold value; and

controlling, with the vehicle dynamics control system, at least one vehicle system selected from the group consisting of a brake system, a steering system, an engine, a transmission and a suspension system.

13. The method according to claim 1, which comprises:

monitoring the friction coefficient and performing a vehicle dynamics control by engaging a vehicle dynamics control system, if the friction coefficient falls below a given threshold value; and

controlling, with the vehicle dynamics control system, at least one vehicle system selected from the group consisting of a brake system, a steering system, an engine, a transmission and a suspension system.

14. The method according to claim 1, which comprises:

determining a wheel slip angle of a front wheel of the vehicle; and

performing a vehicle dynamics control by controlling a steering system of the vehicle such that a torque assist for a steering wheel of the vehicle is decreased, if the wheel slip angle of the front wheel exceeds a given threshold value.

15. The method according to claim 1, which comprises controlling a steering system of the vehicle such that a torque assist for a steering wheel of the vehicle is decreased, if the friction coefficient falls below a given threshold value.

16. The method according to claim 1, which comprises:

determining a wheel slip angle of a rear wheel of the vehicle; and

performing a vehicle dynamics control by controlling an active steering system of the vehicle such that a steering angle of a front wheel is increased, if the wheel slip angle of the rear wheel exceeds a given threshold value.

17. The method according to claim 1, which comprises:

determining a wheel slip angle of a rear wheel of the vehicle; and

performing a vehicle dynamics control by controlling an active steering system of the vehicle such that a steering angle of a front wheel is increased, if the wheel slip angle of the rear wheel exceeds a given threshold value and the friction coefficient falls below a given threshold value.

18. The method according to claim 1, which comprises:

acquiring inertial sensor data indicative of a motion of the vehicle; and

determining the lateral velocity of the vehicle as a function of vehicle data including at least the inertial sensor data.