LANE KEEPING ASSISTANCE SYSTEM AND METHOD FOR AUTOMOTIVE VEHICLE

• US 20020169531A1
• Filed: 08/16/2001
• Published: 11/14/2002
• Est. Priority Date: 09/05/2000
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Sato, Shigeki, Kawazoe, Hiroshi, Shimakage, Masayasu, Sadano, On
• Granted Patent: US 6,493,619 B2
• Time in Patent Office: Days
• 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 5/0463 calculating assisting torque from the motor based on driver input

Abstract

In lane keeping assistance system and method for an automotive vehicle, a control current (Iout) to be outputted to a motor during an automatic steering mode is detected, a filter is provided for the detected control current to pass only signal components of the detected control current whose frequencies are lower than a predetermined cut-off frequency value (fstr, fstr_low, fstr_mid, fstr_hi) to derive a filtered control current (Iout_lpf), a determination of whether a manual steering intervention to the automatic steering occurs is made according to a magnitude of the filtered control current, and the control current outputted to the motor is reduced toward zero when the manual steering intervention is determined to occur according to a result of determination that the magnitude of the filtered control current (Iout_lpf) is in excess of a predetermined threshold current value (Iout_lpf_th).

Claims

1. A lane keeping assistance system for an automotive vehicle, comprising:

a traffic lane information detector to detect an information related to a traffic lane on which the vehicle is about to run;

a steering angle sensor to detect a steering angle of a steering wheel of the vehicle;

a steering position changing section by which the steering wheel of the vehicle is enabled to be displaced independently of a manual steering operation through the steering wheel;

a controlled steering target value setting section that sets a controlled steering target value when a controlled steering to follow the traffic lane is carried out on the basis of at least the traffic lane related information detected by the traffic lane information detector and the steering angle detected by the steering angle sensor;

a controlled steering command value setting section that outputs a control command value in accordance with the controlled steering target value;

a control command value filtering section that filters the control command value to pass only frequency components of the control command value lower than a predetermined filter threshold value to derive a filtered control command value during an execution of the controlled steering;

a manual steering intervention detector to detect a steering intervention state to the controlled steering by the manual steering operation when the filtered control command value is in excess of a predetermined threshold control command value; and

a controlled steering target value limiter to reduce the control command value toward zero value to suppress the controlled steering target value toward a lower value direction including zero when the manual steering intervention is detected by the manual steering intervention detector.

2. A lane keeping assistance system for an automotive vehicle as claimed in claim 1, further comprising:

a vehicular velocity detector to detect a vehicular velocity of the vehicle; and

a predetermined threshold value varying section that varies the predetermined filter threshold value when the control command value filtering section provides the filter for the control command value to pass only predetermined frequency components lower than the predetermined filter threshold value, and

wherein the predetermined threshold value varying section varies the predetermined threshold value of the filter thereof toward a higher frequency side as the detected vehicular velocity becomes increased.

3. A lane keeping assistance system for an automotive vehicle as claimed in claim 1, further comprising a lateral displacement detector to detect a lateral displacement of the vehicle from a center position of the traffic lane on the basis of the traffic lane information from the traffic lane information detector and wherein the manual steering intervention detector detects the steering intervention state by the manual steering operation when the filtered control command value is in excess of the predetermined threshold control command value and the detected lateral displacement is in excess of an external disturbance determination threshold value.

4. A lane keeping assistance system for an automotive vehicle as claimed in claim 1, wherein the steering position changing section comprises an electric motor and the control command value is a current to be supplied to the electric motor.

5. A lane keeping assistance system for an automotive vehicle as claimed in claim 1, wherein the filter of the control command value filtering section comprises a low-pass filter and the predetermined filter threshold value is a cut-off frequency of the low-pass filter.

6. A method applicable to a lane keeping assistance system for an automotive vehicle in which a control current is outputted to a motor of an automatic steering actuator coupled to a vehicular steering system to provide a steering force thereto to follow the vehicle along a traffic lane on a road located in a vehicular forwarding direction during a vehicular run in an automatic steering mode, the method comprising:

detecting the control current to be outputted to the motor during the automatic steering mode;

providing a filter for the detected control current to pass only signal components of the detected control current whose frequencies are lower than a predetermined threshold frequency value of the filter to derive a filtered control current;

determining whether a manual steering intervention to the automatic steering occurs according to a magnitude of the filtered control current, the manual steering intervention being determined to occur depending on whether the magnitude of the filtered control current is in excess of a predetermined threshold current value of the filter; and

reducing the control current outputted to the motor toward zero value when, at the manual steering intervention determining step, the manual steering intervention is determined to occur according to a result of determination that the magnitude of the filtered control current is in excess of the predetermined threshold current value.

7. A method applicable to a lane keeping assistance system for an automotive vehicle as claimed in claim 6, further comprising detecting a vehicular velocity and wherein the predetermined threshold frequency value is a cut-off frequency of the filter, the cut-off frequency being varied toward a higher frequency side as the detected vehicular velocity becomes higher.

8. A method applicable to a lane keeping assistance system for an automotive vehicle as claimed in claim 6, further comprising:

detecting a vehicular velocity, wherein the filter comprises a low vehicular velocity low-pass filter having a lowest cut-off frequency (fstr_low), a middle vehicular velocity low-pass filter having a second lowest cut-off frequency (fstr_mid), and a high vehicular velocity low-pass filter having a highest vehicular velocity cut-off frequency (fstr_hi), and wherein, at the filter providing step, one of the low-pass filters is selected according to a magnitude of the detected vehicular velocity and the filtered control current is calculated.

9. A method applicable to a lane keeping assistance system for an automotive vehicle as claimed in the claim 8, further comprising detecting a traffic lane related information and detecting a lateral deviation of a vehicular position from a center position of the traffic lane on the basis of the detected traffic lane related information and wherein, at the manual steering intervention determining step, the manual steering intervention is determined to occur when the filtered control current is in excess of the predetermined threshold current value and when the detected lateral deviation is in excess of an external disturbance determination threshold value.

10. A method applicable to a lane keeping assistance system for an automotive vehicle as claimed in claim 9, wherein, at the control current reducing step, the control current is gradually reduced toward zero value.

11. A lane keeping assistance system for an automotive vehicle, comprising:

traffic lane information detecting means for detecting an information related to a traffic lane on which the vehicle is about to run;

steering angle detecting means for detecting a steering angle of a steering wheel of the vehicle;

steering position changing means by which the steering wheel of the vehicle is enabled to be displaced independently of a manual steering operation through the steering wheel;

controlled steering target value setting means for setting a controlled steering target value when a controlled steering to follow the traffic lane is carried out on the basis of at least the traffic lane related information detected by the traffic lane information detecting means and the steering angle detected by the steering angle detecting means;

controlled steering command value setting means for outputting a control command value in accordance with the controlled steering target value;

control command value filtering means for filtering the control command value to pass only frequency components of the control command value lower than a predetermined filter threshold value to derive a filtered control command value during an execution of the controlled steering;

manual steering intervention detecting means for detecting a steering intervention state to the controlled steering by the manual steering operation when the filtered control command value is in excess of a predetermined threshold control command value; and

controlled steering target value limiting means for reducing the control command value toward zero value to suppress the controlled steering target value toward a lower value direction including zero when the manual steering intervention is detected by the manual steering intervention detecting means.