Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1998-09-11
2001-01-23
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S001000, C180S167000, C180S168000, C180S169000, C180S280000, C180S421000, C180S422000
Reexamination Certificate
active
06178365
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a steering control system for a vehicle.
2. Description of the Related Art
Earlier patent applications proposed by the assignee, including those made public by Japanese Laid-Open Patent Application Nos. Hei 5(1993)-197,423 and Hei 9(1997)-221,054, teach vehicle steering control system technologies that provide steering angle assistance for keeping the vehicle on a desired course of travel along a lane of a road.
By providing fine steering assistance while preventing vehicle lane wandering, these technologies greatly reduce the burden on the driver, which tends to increase particularly during long, high-speed driving on an expressway or the like.
In view of the interference or interaction between this type of steering assistance control and driver steering, the control should preferably be effected to provide assistance through torque (steering force) rather than steering angle.
When the vehicle is equipped with both a lane holding steering torque assist control system of such type and a steering torque assist control system of the power steering, hereinafter referred to as the power steering torque assist, an issue arises regarding how to switch the mode of control between the two systems. If the assist torque changes abruptly at the time of switching, this will be disadvantageous in that, for example, the vehicle driver experiences annoyance upon sensing a change in steering torque assist.
SUMMARY OF THE INVENTION
An object of this invention is therefore to provide a steering control system for a vehicle that, in a vehicle equipped with two types of steering torque assist control systems, determines the assist torque to ensure switching of the mode of control smoothly, thereby preventing the occurrence of disadvantages including that the vehicle driver experiences annoyance upon sensing a change in steering torque assist.
Moreover, when the steering torque assist control is conducted in such a manner that the vehicle travels along a (lane holding steering torque assist), if the driver has an intention to steer by himself for a reason such as to change lanes or to avoid an obstacle on the road, the mode of control should preferably be switched immediately from the lane holding steering torque assist control to the torque assist of the ordinary power steering.
Another object of this invention is therefore to provide a steering control system for a vehicle that, in a vehicle equipped with two types of steering torque assist control systems, enables immediate switching of the mode of control from the lane holding steering torque assist to the torque assist of the ordinary power steering in response to the driver's intention.
Furthermore, if the steering torque assist control is switched to that of the power steering torque assist in response to the driver's intention as mentioned above, it should still preferable to ensure smooth switching so as not to cause disadvantages from occurring including that the vehicle driver experiences annoyance upon sensing a change in steering torque assist.
Still another object of this invention is therefore to provide a steering control system for a vehicle that, in a vehicle equipped with two types of steering torque assist control systems, determines the assist torque to ensure smooth switching of the mode of control when the switching is effected in response to the driver's intention, thereby preventing disadvantages including that the vehicle driver experiences annoyance upon sensing a change in steering torque assist.
In order to achieve this object, there is provided a system for controlling steering of a vehicle, including: steering means having an actuator which steers driven wheels of the vehicle; first steering control means for controlling the actuator; first detecting means for detecting a lane condition of a road on which the vehicle travels; second detecting means for detecting motion of the vehicle; steering assist torque calculating means for calculating a steering assist torque necessary for holding a positional relationship between the vehicle and the lane condition; torque detecting means for detecting a steering torque manually applied to the steering means by the driver; and second steering control means for calculating a torque command to be output to the first steering control means based on the steering assist torque calculated by the steering assist torque calculating means and the detected steering torque to control the actuator such that the torque command decreases. Said system includes switching means for switching between the mode of control by the first steering control means and the mode of control by the second steering control means gradually with respect to time, thereby ensuring to switch the mode of control smoothly and preventing the occurrence of disadvantages including that the vehicle driver experiences annoyance upon sensing a change in steering assist.
REFERENCES:
patent: 5904223 (1999-05-01), Shimizu et al.
patent: 5913375 (1999-06-01), Nishikawa
patent: 5927430 (1999-07-01), Mukai et al.
patent: 6041884 (2000-03-01), Shimizu et al.
patent: 6053270 (2000-04-01), Nishikawa et al.
patent: 5-197423 (1993-08-01), None
Ishida Shinnosuke
Kawagoe Hiroyuki
Matsuno Kaoru
Teramoto Tomoaki
Arent Fox Kintner & Plotkin & Kahn, PLLC
Cuchlinski Jr. William A.
Hernandez Olga
Honda Giken Kogyo Kabushiki Kaisha
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