Video enhanced stability control in road vehicles

• US 20050246101A1
• Filed: 04/29/2005
• Published: 11/03/2005
• Est. Priority Date: 10/30/2002
• Status: Active Grant

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Tucker, Mark Richard, Courtenay, William John Andres
• Granted Patent: US 7,062,382 B2
• Time in Patent Office: Days
• US Class Current: 701/301
• 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 2201/085 using several actuators; Coordination of the lane keeping system with other control systems
• CPC Class Codes: B60T 2201/087 using active steering actuation
• CPC Class Codes: B60T 2201/089 using optical detection
• 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: B60T 8/1764 Regulation during travel on surface with different coefficients of friction, e.g. between left and right sides, mu-split or between front and rear
• 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 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means
• CPC Class Codes: G05D 2201/0213 Road vehicle, e.g. car or truck

Abstract

A stability control system for road vehicles comprising a limit handling assistance controller which uses video lane detection measurements in conjunction with vehicle dynamics information, including inertial brakes and steering measurements to control vehicle EPS and VSC systems to assist the driver stabilize the vehicle and correct for any lane offset prior to and/or during of understeer, oversteer, split-μ and heavy breaking conditions, and lane changes.

Claims

1. A stability control system for road vehicles comprising:

a video image processing system;

an offset correction device connected to said video image processing system, said offset correction device operative to detect at least one of lane offsets and vehicle trajectory offsets as would be imposed on a vehicle undergoing a dynamic system change; and

a corrective control device connected to said offset correction device that is operative to the vehicle trajectory.

2. A stability control system for road vehicles comprising.

a video image processing system;

and

a limit handling assistance controller connected to said video image processing system and which uses video lane detection measurements in conjunction with vehicle dynamics information, including inertial brakes and steering measurements, to control vehicle Electronic Power Steering (EPS) and Vehicle Stability Control (VSC) systems to assist the driver to stabilise the vehicle and correct for any lane offset both prior to and during at least one of the conditions of understeer, oversteer, split-μ and

heavy breaking conditions, and lane changes.

3. A stability control system as claimed in claim 2, wherein said limit handling assistance controller comprises:

a scenario control which receives vehicle measurements and Human Machine Interface (HMI) inputs and estimates therefrom the dynamic state of the vehicle, such as understeer/oversteer/heavy braking, and the intentions of the driver, such as lane change, whereby to provide a series of scenario flags for use in informing the controller of what vehicle control action is available;

a position and yaw rate control which receives vehicle measurement data and line detection data and calculates one of a yaw rate required to return the vehicle to the centre of its lane and a yaw rate required for lane transition if a lane change flag is detected; and

a steering and braking control which receives said calculated yaw rate and the vehicle measurement data and is operative to calculate steering yaw rate and braking yaw rate demands for transfer to the vehicle EPS and VSC systems.

4. A stability control system as claimed in claim 3, further including an application control device coupled to a mode control and acting as a mode switch for connecting the steering and braking yaw rate demands produced by the steering and braking control to the vehicles EPS and VSC systems when said mode control indicates that the system is active.

5. A stability control system as claimed in claim 4 wherein the steering and brake control comprises:

a steering and braking yaw demand allocator,

a steering demand control, and

a braking demand control,

the steering and braking yaw demand allocator proportioning said yaw rate demanded by said position and yaw rate control to steering demand and braking demand controls according to said scenario flags.

6. A stability control system as claimed in claim 5, wherein in said steering demand control, said steering yaw rate demand is compared to feedback measurements of steering wheel angle and rotational rate to provide an assist steering column torque demand for transmission to the vehicle EPS system.

7. A stability control system as claimed in claim 6, wherein in said braking demand control, said braking yaw rate demand is compared to feedback estimates of brake pressures whereby to provide brake pressure demands for transmission to the vehicle VSC system.

8. A stability control system as claimed in claim 7, in which in the case of an understeering vehicle condition detected by the vehicle VSC, an appropriate wheel is arranged to be braked to achieve a desired yaw rate in accordance with a driver'"'"'s command expressed via the steering wheel, whereby to decelerate the vehicle to reduce the understeer.

9. A stability control system as claimed in claim 8, in which once the understeer has been reduced sufficiently for the front tyres to be no longer saturated, a torque is arranged to be demanded of the steering to assist the driver to correct for any lane offsets detected by a video lane detection sensor providing said video lane detection measurements.

10. A stability control system as claimed in claim 7, in which, for the purposes of preventative understeers or oversteer, the video lane detection measurements are used to obtain look-ahead information of a bend, the controller being arranged to demand brake intervention to decelerate the vehicle to an appropriate speed so that the bend can be safely negotiated without one of understeer and oversteer being provided.

11. A stability control system as claimed in claim 7 in which, in the case of an oversteering vehicle condition detected by the vehicle VSC, a torque is arranged to be applied to the steering to assist the driver in stabilising the vehicle following which, if the oversteer progresses to a threshold, the VSC is arranged to brake an appropriate wheel to stabilise the vehicle and achieve a desired yaw rate in accordance with a driver'"'"'s command via the steering wheel.

12. A stability control system as claimed in claim 11, in which, during and subsequent to the oversteer correction phases of the oversteer control, an additional overlay torque is arranged to be demanded of the steering to assist the driver correct for lane offsets detected by a video lane detection sensor providing said video lane detection measurements.

13. A stability control system as claimed in claim 7 in which during heavy braking while running in a lane, a torque is demanded of the steering system using vehicle inertial, steering and video lane detection measurements to assist the driver to stabilise the vehicle and keep the vehicle in that lane when undergoing said braking.

14. A stability control system as claimed in claim 7 in which, in a split-μ

stop, the driver is assisted to balance the yaw moment due to the asymmetric longitudinal braking force by demanding a torque to the steering system to assist the driver in achieving the required counter moment.

15. A stability control system as claimed in claim 14, wherein the system includes a video lane detection sensor and further wherein an additional torque to assist the driver correct for lane offsets detected by said video lane detection sensor is used to augment the first mentioned torque.

16. A stability control system as claimed in claim 7, wherein the system includes a video lane detection sensor and further wherein when a lane change selected by the driver is detected by said video lane detection sensor in association with steering and vehicle inertial sensors, a torque is arranged to be demanded of the steering system to assist the driver in making the lane change.

17. A stability control system for road vehicles having an Active Torque Overlay (ATO) system and comprising a limit handling assistance controller which uses video lane detection measurements in conjunction with vehicle dynamics information, including inertial brakes and steering measurements to control the ATO system to assist the driver in stabilizing the vehicle and correcting for any lane offset prior to and during at least one of the conditions of understeer, oversteer, split-μ

and heavy braking conditions, and lane changes.