Power steering system and control method of the same

• US 20070021889A1
• Filed: 07/18/2006
• Published: 01/25/2007
• Est. Priority Date: 07/25/2005
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Tsuchiya, Yoshiaki
• Granted Patent: US 8,055,409 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• 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 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

With a power steering system and a control method of a power steering system provided, a basic assist control amount is calculated based on a steered state of a driver'"'"'s steering wheel. A compensation control amount used to compensate for the basic assist control amount is calculated, and corrected, during calculation of the compensation control amount, based on a lane-position maintenance assist control amount which is calculated based on a running state of a vehicle and which is used to maintain a predetermined lane-position. A target assist control amount applied to a steering mechanism is calculated based on the basic assist control amount, the lane-position maintenance assist control amount, and the compensation control amount.

Claims

1. A power steering system, comprising:

a controller that calculates a basic assist control amount based on a steered state of a driver'"'"'s steering wheel, and that calculates a compensation control amount used to compensate for the basic assist control amount and corrects, during calculation of the compensation control amount, the compensation control amount based on a lane-position maintenance assist control amount which is calculated based on a running state of a vehicle and which is used to maintain a predetermined lane-position, wherein

the controller calculates a target assist control amount applied to a steering mechanism based on the basic assist control amount, the lane-position maintenance assist control amount, and the compensation control amount.

2. The power steering system according to claim 1, wherein

the basic assist control amount includes a basic assist torque, the compensation control amount includes a compensation torque, the lane-position maintenance assist control amount includes a lane-position maintenance assist torque, and the target assist control amount includes a target assist torque.

3. The power steering system according to claim 1, wherein

the lane-position maintenance assist control amount includes a steering angle speed.

4. The power steering system according to claim 1, wherein

the compensation control amount includes a damping control amount, and

the controller makes a correction to increase an absolute value of the damping control amount, when the lane-position maintenance assist control amount deviates from a value at or around zero.

5. The power steering system according to claim 4, wherein

the absolute value of the damping control amount increases as an absolute value of the lane-position maintenance assist control amount increases.

6. The power steering system according to claim 4, wherein

the controller continues the correction to increase the absolute value of the damping control amount until a predetermined time has elapsed since the lane-position maintenance assist control amount is the value at or around zero.

7. The power steering system according to claim 1, wherein

the compensation control amount includes a torque derivative control amount that is calculated based on a derivative value of a steering torque, and the controller makes a correction to increase an absolute value of the torque derivative control amount, when the lane-position maintenance assist control amount deviates from a value at or around zero.

8. The power steering system according to claim 7, wherein

the absolute value of the torque derivative control amount increases as an absolute value of the lane-position maintenance assist control amount increases.

9. A control method of a power steering system, comprising:

calculating a basic assist control amount based on a steered state of a driver'"'"'s steering wheel;

calculating a compensation control amount used to compensate for the basic assist control amount and correcting, during calculation of the compensation control amount, the compensation control amount based on a lane-position maintenance assist control amount which is calculated based on a running state of a vehicle and which is used to maintain a predetermined lane-position, and

calculating a target assist control amount applied to a steering mechanism based on the basic assist control amount, the lane-position maintenance assist control amount, and the compensation control amount.

10. The control method according to claim 9, wherein

the basic assist control amount includes a basic assist torque, the compensation control amount includes a compensation torque, the lane-position maintenance assist control amount includes a lane-position maintenance assist torque, and the target assist control amount includes a target assist torque.

11. The control method according to claim 9, wherein

the lane-position maintenance assist control amount includes a steering angle speed.

12. The control method according to claim 9, wherein

the compensation control amount includes a damping control amount, and

a correction is made to increase an absolute value of the damping control amount, when the lane-position maintenance assist control amount deviates from a value at or around zero.

13. The control method according to claim 12, wherein

the absolute value of the damping control amount increases as an absolute value of the lane-position maintenance assist control amount increases.

14. The control method according to claim 12, wherein

the correction is continued to increase the absolute value of the damping control amount until a predetermined time has elapsed since the lane-position maintenance assist control amount is the value at or around zero.

15. The control method according to claim 9, wherein

the compensation control amount includes a torque derivative control amount that is calculated based on a derivative value of a steering torque, and

a correction is made to increase an absolute value of the torque derivative control amount, when the lane-position maintenance assist control amount deviates from a value at or around zero.

16. The control method according to claim 15, wherein

the absolute value of the torque derivative control amount increases as an absolute value of the lane-position maintenance assist control amount increases.