Apparatus for and method of steering vehicle

• US 20020038171A1
• Filed: 09/27/2001
• Published: 03/28/2002
• Est. Priority Date: 09/28/2000
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Obata, Takeaki, Deguchi, Yoshitaka
• Granted Patent: US 6,549,835 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B62D 15/0265 Automatic obstacle avoidance by steering
• CPC Class Codes: B62D 15/027 Parking aids, e.g. instruction means
• CPC Class Codes: B62D 7/159 characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition

Abstract

Unless the steering operation quantity detected by a steering quantity detection unit indicates that the vehicle is advancing almost rectilinearly, an approach disallowed area present toward the outer side of the turning vehicle relative to the front of the vehicle along the advancing direction, such as a road boundary, a blocking wall or a white line, is detected by an approach disallowed area detection unit. A mode judging unit judges that a steering angle limit mode is set if an approach disallowed area has been detected. An α calculating unit calculates an angle α formed by the orientation of the approach disallowed area boundary and the orientation of the vehicle. In the steering angle limit mode, a target front steering angle calculating unit performs an arithmetic operation by imposing a limit on the absolute value of the target steering angle for the front of the vehicle along the advancing direction so as to ensure that the absolute value does not exceed the maximum value of approximately α.

Claims

1. A vehicle steering apparatus comprising;

an approach disallowed area detection device that detects an approach disallowed area present toward an outer side of a turning vehicle relative to a direction in which the vehicle advances;

an α

calculating device that performs an arithmetic operation to calculate an angle α

formed by an orientation of a boundary of the approach disallowed area detected by said approach disallowed area detection device and an orientation of the vehicle; and

a steering angle control device that imposes a limit on a steering angle for wheels at a front side of the vehicle so that the front steering angle does not exceed a predetermined value equal to or smaller than α

while implementing control on a rear steering angle for wheels at a rear side of the vehicle if the front steering angle exceeds the angle α

calculated by said α

calculating device.

2. A vehicle steering apparatus according to claim 1, wherein;

the predetermined value is α

.

3. A vehicle steering apparatus according to claim 1, wherein;

the predetermined value represents an angle formed by a line passing through an outer end of the turning vehicle along the advancing direction and extending perpendicular to the orientation of the approached disallowed area boundary and a line connecting a front (rear) left wheel and a front (rear) right wheel.

4. A vehicle steering apparatus according to claim 1, wherein;

the predetermined value represents an angle formed by a line passing through a portion of the vehicle set closest to the approach disallowed area boundary and extending perpendicular to the orientation of the approached disallowed area boundary and a line connecting a front (rear) left wheel and a front (rear) right wheel.

5. A vehicle steering apparatus according to claim 1, wherein;

said steering angle control device implements control on the rear steering angle along a direction in which a turning radius becomes smaller, as an extent to which the front steering angle exceeds the predetermined value increases.

6. A vehicle steering apparatus according to claim 1, wherein;

said steering angle control device implements control on the rear steering angle so as to achieve a turning radius equal to a turning radius realized when no limit is imposed on the front steering angle, if a limit is imposed on the front steering angle.

7. A vehicle steering apparatus according to claim 1, wherein;

said steering angle control device includes;

a front steering angle calculating device that calculates a front steering angle for wheels at a front side of the vehicle; and

a rear steering angle calculating device that calculates a rear steering angle for wheels at a rear side of the vehicle; and

said steering angle control device imposes a limit on the front steering angle calculated by said front steering angle calculating device so that the front steering angle does not exceed the predetermined value equal to or smaller than a while implementing control on the rear steering angle calculated by said rear steering angle calculating device, if the front steering angle calculated by said front steering angle calculating device exceeds the angle α

calculated by said α

calculating device.

8. A vehicle steering apparatus according to claim 1, wherein;

said steering angle control device implements reverse phase control on a rear wheel at a steering angle value set at half of the front wheel steering angle if no limit is imposed on the front steering angle, whereas said steering angle control device implements reverse phase control on the rear wheel with the steering angle value set at (1+α

) times half of the steering angle at the front wheel when a limit is imposed on the front steering angle.

9. A vehicle steering apparatus according to claim 1, wherein;

said approach disallowed area detection device includes a position detection unit that detects a vehicle position, an advancing direction detection unit that detects a direction in which the vehicle is advancing and a storage unit in which road information is stored, and detects the approach disallowed area boundary present toward the outer side of the turning vehicle relative to a direction in which the vehicle is advancing, based upon the current vehicle position and the advancing direction that have been detected and the road information read out from said storage unit.

10. A vehicle steering apparatus according to claim 1, further comprising;

a vehicle speed detection device that detects a vehicle traveling speed, wherein;

said steering angle control device does not impose any limit on the front steering angle if the vehicle speed detected by said vehicle speed detection device is equal to or higher than a predetermined vehicle speed.

11. A vehicle steering apparatus according to claim 1, further comprising;

a limit input device that is operated by a driver, wherein;

said steering angle control device imposes a limit on the front steering angle so that the front steering angle does not exceed the predetermined value equal to or smaller than α

while implementing control on the rear steering angle, if an operation to impose a limit on the front steering angle is performed through said limit input device and an approach disallowed area is detected by said approach disallowed area detection device.

12. A vehicle steering apparatus according to claim 1, further comprising;

a current position detection device that detects a current position of the vehicle; and

a point setting judging device that makes a judgment as to whether or not the current vehicle position detected by said current position detection device is at a preset point, wherein;

said steering angle control device imposes a limit on the front steering angle so that the front steering angle does not exceed a predetermined value equal to or smaller than α

while implementing control on the rear steering angle if it is judged by said point setting judging device that the current position of the vehicle is at the preset point.

13. A vehicle steering apparatus according claim 1, further comprising;

a steering operation quantity detection device that detects a quantity of operation performed at a steering wheel, wherein;

said steering angle control device clears a limit on the front steering angle once the steering operation quantity detected by said steering operation quantity detection device is substantially at 0 after the limit has been imposed on the front steering angle so that the front steering angle does not exceed the predetermined value equal to or smaller than α

.

14. A vehicle steering apparatus according to claim 1, further comprising;

an alerting device that alerts the driver if a limit is imposed by said steering angle control device on the front steering angle so that the front steering angle does not exceed the predetermined value equal to or smaller than α

.

15. A vehicle steering apparatus comprising;

an approach disallowed area detection means for detecting an approach disallowed area present toward an outer side of a turning vehicle relative to a direction in which the vehicle is advancing;

an α

calculation means for calculating an angle α

formed by an orientation of a boundary of the approach disallowed area detected by said approach disallowed area detecting means and an orientation of the vehicle and;

a steering angle control means for imposing a limit on a front steering angle for wheels at a front side of the vehicle so that the front steering angle does not exceed a predetermined value equal to or smaller than α

while implementing control on a rear steering angle for wheels at the rear side of the vehicle if the front steering angle exceeds the angle α

calculated by said α

calculating means.

16. A vehicle steering method comprising steps of;

detecting an approach disallowed area present toward an outer side of a turning vehicle relative to a direction in which the vehicle is advancing;

calculating an angle α

formed by an orientation of a boundary of the approach disallowed area thus detected and an orientation of the vehicle; and

imposing a limit on a front steering angle for wheels at the front side of the vehicle so that the front steering angle does not exceed a predetermined value equal to or smaller than α

while implementing control on a rear steering angle for wheels at the rear side of the vehicle if the front steering angle exceeds the angle α

that has been calculated.