Vehicle steering control system

• US 6,256,561 B1
• Filed: 10/08/1999
• Issued: 07/03/2001
• Est. Priority Date: 10/12/1998
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Asanuma, Nobuyoshi
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US09/414,545
• Time in Patent Office: 634 Days
• Field of Search: 701/41, 701/65, 701/70, 701/72, 701/83, 701/84, 701/90, 180/197
• US Class Current: 701/41
• CPC Class Codes: B60T 2201/08 Lane monitoring; Lane Keeping Systems
• CPC Class Codes: B60T 2201/087 using active steering actuation
• CPC Class Codes: B62D 1/286 Systems for interrupting non-mechanical steering due to driver intervention
• 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

Abstract

A system for controlling steering of a vehicle, including an electric motor used for power-steering torque assist control. The system has an navigation system whose output is used to correct the detected steering angle input by the vehicle driver. A desired yaw rate is determined based on the corrected steering angle and the detected vehicle speed using a yaw rate model, thereby enabling to conduct the aforesaid lane-keeping-steering torque assist control in a more appropriate manner. Further, if the vehicle driver expresses a positive intention to steer the vehicle by himself, for example, so as to avoid an obstacle present on the road, the control is discontinue to meet the wishes of the vehicle driver. Furthermore, the system monitors the steering of the vehicle driver to prevent the vehicle driver from relying upon this steering assist control to an excessive extent.

Claims

1. A system for controlling steering of vehicle, comprising:

an actuator which steers driven wheels of the vehicle;

vehicle running condition detecting means for detecting running conditions of the vehicle including at least a turning behavior of the vehicle, a speed of the vehicle and a steering angle of the vehicle;

steering torque detecting a means for detecting a steering torque inputted by a driver of the vehicle;

road detecting means for detecting a lane boundary which defines a road on which the vehicle is running;

road condition information outputting means for outputting information of conditions of the road including at least a curvature of the road;

steering angle correcting means for correcting the detected steering angle based on the detected road and the outputted information of the conditions of the road;

desired vehicle turning behavior determining means for determining a desired turning behavior of the vehicle based on at least the corrected steering angle and the detected vehicle speed using a preset model;

assist torque determining means for determining an error between the desired vehicle turning behavior and the detected vehicle turning behavior and for determining an assist torque for causing the vehicle to run along the road based on the determined error; and

manipulated variable determining means for determining a manipulated variable to be supplied to the actuator based on the determined assist torque.

2. A system according to claim 1, wherein the assist torque determining means includes:

error discriminating means for discriminating whether the determined error is a negative value; and

torque discriminating means for discriminating whether the detected steering torque exceeds a predetermined first torque;

and determines the assist torque to be zero when the determined error is discriminated to be a negative value and the detected steering torque is discriminated to exceed the predetermined first torque.

3. A system according to claim 2, wherein the assist torque determining means further includes:

second error discriminating means for discriminating whether the determined error in absolute value exceeds a reference value;

and determines the assist torque to be zero when the determined error is discriminated to be a negative value, the detected steering torque is discriminated to exceed the predetermined first torque and the determined error in absolute value is discriminated to exceed the reference value.

4. A system according to claim 1, wherein the assist torque determining means includes:

error discriminating means for discriminating whether the determined error is a negative value;

torque discriminating means for discriminating whether the detected steering torque exceeds a predetermined second torque;

time measuring means for beginning measurement of time lapse when the determined error is discriminated to be a negative value and the detected steering torque is discriminated to be less than or equal to the predetermined second torque;

time discriminating means for discriminating whether the measured time exceeds a determined first time; and

alerting means for alerting the vehicle driver when the measured time is discriminated to exceed the predetermined first time.

5. A system according to claim 4, wherein the assist torque determining means further includes:

steering angle discriminating means for discriminating whether the steering angle exceeds a predetermined steering angle;

and the time measuring means begins the measurement of time lapse when the determined error is discriminated to be a negative value, the detected steering torque is discriminated to be less than or equal to the predetermined second torque and the steering angle is discriminated to exceed the predetermined steering angle.

6. A system according to claim 4, wherein the assist torque determining means further includes:

error discriminating means for discriminating whether the determined error in absolute value exceeds a reference value;

and the time measuring means begins the measurement of time lapse when the determined error is discriminated not to be a negative value, the detected steering torque is discriminated to be less than or equal to the predetermined second torque and the determined error in absolute value is discriminated to exceed the reference value.

7. A system according to claim 4, wherein the assist torque determining means further includes:

second torque discriminating means for discriminating whether the detected steering torque exceeds a predetermined torque;

and the time measuring means begins the measurement of time lapse when the determined error is discriminated to be a negative value, the detected steering torque is discriminated to be less than or equal to the predetermined second torque and the detected steering torque is discriminated not to exceed the predetermined torque.

8. A system according to claim 4, wherein the assist torque determining means further includes:

second time discriminating means for discriminating whether the measured time exceeds a predetermined second time;

and determines the assist torque to be zero when the measured time is discriminated to exceed the predetermined second time.

9. A system according to claim 8, wherein the alerting means alerts the vehicle driver when the measured time is discriminated to exceed the predetermined second time.

10. A system according to claim 1, wherein the vehicle turning behavior indicates a yaw rate of the vehicle.