Vehicle steering control system

• US 6,212,453 B1
• Filed: 09/10/1999
• Issued: 04/03/2001
• Est. Priority Date: 09/11/1998
• 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: Ishida, Shinnosuke, Kawagoe, Hiroyuki
• Primary Examiner(s): Nguyen, Tan
• Assistant Examiner(s): Tran, Dalena
• Application Number:
  US09/393,963
• Time in Patent Office: 571 Days
• Field of Search: 701/41, 701/42, 701/28, 701/36, 180/443, 180/446, 180/422, 180/168, 340/937, 340/938, 340/939, 318/580
• 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 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 5/0463 calculating assisting torque from the motor based on driver input
• 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

Abstract

A system for controlling steering of a vehicle, including an electric motor used for power-steering torque assist control. In the system, the lane-keeping-steering assist torque TLK for causing the vehicle to run along the center of a road existing ahead of the vehicle is calculated, while the power-steering assist torque TPS for assisting the vehicle driver'"'"'s steering is calculated. Then, ratios RTO1 and RTO2 are calculated based on the detected steering torque. The assist torques TLK, TPS are corrected by multiplication with the ratios RTO1, RTO2 respectively and are added together to determine a final assist torque TA, and based on the final assist torques TA, a motor current to be supplied to the electric motor is determined, thereby enabling to effectively prevent the two kinds of control from interfering with each other so as not to adversely affect the vehicle driver'"'"'s perception of vehicle steering response. Additional ratios are determined based on the detected steering torque change and the vehicle speed.

Claims

1. A system for controlling steering of a vehicle, including:

an actuator which steers driven wheels of the vehicle;

1st assist torque calculating means for calculating a first assist torque for causing the vehicle to run along a reference line of a road existing ahead of the vehicle;

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

2nd assist torque calculating means for calculating a 2nd assist torque for assisting vehicle driver'"'"'s steering of the vehicle in accordance with a predetermined characteristic based on the detected steering torque;

manipulated variable calculating means for calculating a manipulated variable to be supplied to the actuator based on the calculated 1st and 2nd assist torques; and

assist torque correcting means for correcting the calculated 1st and 2nd assist torques based on at least the detected steering torque; and

wherein

the manipulated variable calculating means for calculating a manipulated variable to be supplied to the actuator based on the corrected 1st and 2nd assist torques.

2. A system according to claim 1, wherein the assist torque correcting means determines correction coefficients based on the detected steering torque, and corrects the calculated 1st and 2nd assist torques by multiplying with the correction coefficients.

3. A system according to claim 2, wherein the assist torque correcting means determines correction coefficients based on the detected steering torque in accordance with two characteristics which are predetermined complementary with each other, and corrects the calculated 1st and 2nd assist torques by multiplying with the correction coefficients respectively.

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

steering torque change determining means for determining a change of the steering torque; and

wherein the assist torque correcting means corrects one of the calculated 1st and 2nd assist torques based on at least the determined change of the steering torque.

5. A system according to claim 4, wherein the assist torque correcting means determines a correction coefficient based on the determined change of steering torque, and corrects the one of the calculated 1st and 2nd assist torques by multiplying with the correction coefficient.

6. A system according to claim 1, wherein the assist torque correcting means includes:

vehicle speed detecting means for detecting a speed of the vehicle; and

wherein the assist torque correcting means corrects the calculated 1st and 2nd assist torques based on at least the detected vehicle speed.

7. A system according to claim 6, wherein the assist torque correcting means determines correction coefficients based on the detected vehicle speed, and corrects the calculated 1st and 2nd assist torques by multiplying with the correction coefficients.

8. A system according to claim 1, wherein the predetermined characteristics, comprising a first characteristic portion and a second characteristic portion each set relative to the detected steering torque such that, for a given change in detected steering torque, an amount of the 2nd assist torque calculated in accordance with the second characteristic portion, is less than that calculated in accordance with the first characteristic portion.

9. A system according to claim 1, further including:

torque comparing means for comparing the detected torque with a predetermined value; and

wherein the assist torque correcting means corrects the calculated 1st and 2nd assist torques based on the detected steering torque when the detected torque is less than or equal to the predetermined value, while correcting the calculated 2nd assist torque when the detected torque is greater than the predetermined value.

10. A system according to claim 1, further including:

torque comparing means for comparing the detected torque with a predetermined value; and

wherein, when the detected torque is less than or equal to the predetermined value, the assist torque correcting means corrects the calculated 1st assist torque based on the detected steering torque, while when the detected torque is greater than the predetermined value correcting the calculated 2nd assist torque.