Lane-keep control system for vehicle

• US 20030062769A1
• Filed: 08/27/2002
• Published: 04/03/2003
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Matsumoto, Shinji, Tange, Satoshi, Yoshizawa, Hiroyuki, Naito, Genpei
• Granted Patent: US 6,708,098 B2
• Time in Patent Office: Days
• US Class Current: 303/146
• CPC Class Codes: B60T 2201/08 Lane monitoring; Lane Keeping Systems
• CPC Class Codes: B60T 2201/083 using active brake actuation
• CPC Class Codes: B60T 8/17557 specially adapted for lane departure prevention road vehicle drive control systems for lane keeping otherwise than by controlling a particular sub-unit B60W30/12
• CPC Class Codes: B60W 2050/143 Alarm means
• CPC Class Codes: B60W 2540/18 Steering angle
• CPC Class Codes: B60W 2720/14 Yaw
• CPC Class Codes: F16H 2059/443 Detecting travel direction, e.g. the forward or reverse movement of the vehicle

Abstract

A lane-keep control system for a host-vehicle is arranged to detect a traveling condition of the host-vehicle, to detect a tendency of a lane deviation of the host-vehicle on the basis of the traveling condition, to calculate a driving/braking force controlled variable of each wheel according to the traveling condition so as to generate a yawing moment directed toward a direction of preventing the lane deviation when the tendency of the lane deviation is detected, to control a driving/braking force according to the driving/braking force controlled variable, to detect a steering state quantity indicative of a quantity of state of a steering wheel, and to correct the driving/braking force controlled variable on the basis of the steering state quantity.

Claims

1. A lane-keep control system for a host-vehicle, comprising:

a control unit configured,

to detect a traveling condition of the host-vehicle,

to determine that there is a tendency of a lane deviation that the host-vehicle is deviating from a traveling lane, on the basis of the traveling condition,

to calculate a driving/braking force controlled variable of each wheel according to the traveling condition so as to generate a yawing moment directed toward a direction of preventing the lane deviation when there is the tendency of the lane deviation,

to detect a steering state quantity indicative of a quantity of state of a steering wheel,

to correct the driving/braking force controlled variable on the basis of the steering state quantity, and

to control a driving/braking force of each wheel according to the driving/braking force controlled variable.

2. The lane-keep control system as claimed in claim 1, wherein the control unit is configured to correct the driving/braking force controlled variable according to the steering state quantity so as to decrease the yawing moment directed toward the direction of preventing the host-vehicle from deviating from the traveling lane when the steering state quantity acts to suppress the lane deviation.

3. The lane-keep control system as claimed in claim 1, wherein the control unit is configured to estimate a yawing moment due to a steering operation from the steering state quantity, and to correct the driving/braking force controlled variable according to the estimated yawing moment.

4. The lane-keep control system as claimed in claim 1, wherein the control unit is configured to calculate a target yawing moment from a difference between a future lateral displacement of the host-vehicle relative to the traveling lane and a lateral displacement limit value, where the future lateral displacement is estimated from the steering state quantity, and to calculate the driving/braking force controlled variable on the basis of the target yawing moment.

5. The lane-keep control system as claimed in claim 4, wherein the control unit is configured to estimate a yawing moment due to a steering operation from the steering state quantity, to obtain a corrected target yawing moment by subtracting the yawing moment due to the steering operation from the target yawing moment, and to correct the driving/braking force controlled variable on the basis of the corrected target yawing moment.

6. The lane-keep control system as claimed in claim 1, wherein the control unit is capable of independently controlling braking forces of right and left wheels of the host-vehicle.

7. The lane-keep control system as claimed in claim 1, wherein the control unit is configured to determine that there is the tendency of the lane deviation when a future lateral displacement of the host-vehicle relative to a traveling lane becomes greater than or equal to a lateral displacement limit value, where the future lateral displacement is estimated from the traveling condition.

8. The lane-keep control system as claimed in claim 1, wherein the driving/braking force control variable includes a target yawing moment MS which is determined from the following expression:

MS=Kdd×

M_S0,

where M_S0=−

K₁×

K₂×

(XS−

X_C), K₁ is a constant determined by vehicle specifications, K₂ is a coefficient which is decreased according to an increase of a vehicle speed, X_C a value obtained by subtracting a half of a host-vehicle width L₀ from a half of a traveling-lane width L, and XS is a future lateral displacement expressed by the following expression,

XS=Tt×

V×

(Φ

+Tt×

V×

β

)+X,

where Tt is a vehicle head time for calculating a front remarking distance, and the front remarking distance is calculated by multiplying the vehicle head time Tt and vehicle speed V of the host-vehicle, Φ

is a yaw angle of the host-vehicle relative to the traveling lane, X is a lateral displacement X of the host-vehicle relative to a center of the traveling lane, and β

is a curvature of the traveling lane.

9. A lane-keep control system of a host-vehicle comprising:

a traveling condition detecting device that detects a traveling condition of the host-vehicle, the traveling condition including a state of a steering wheel;

a brake hydraulic pressure control circuit that independently controls a hydraulic pressure of each wheel cylinder of the host-vehicle to generate a desired braking force of the host-vehicle;

a driving torque control unit that controls a driving torque applied to driving wheels of the host-vehicle; and

a driving/braking force control unit coupled to the traveling condition detecting device, the brake hydraulic control circuit and the driving torque control unit, the driving/braking force control unit being arranged,

to determine that there is a tendency of a lane deviation that the host-vehicle is deviating from a traveling lane, on the basis of the traveling condition,

to calculate a target yawing moment reference value on the basis of the traveling condition when there is the tendency of the lane deviation,

to calculate a target yawing moment by correcting the target yawing moment reference value according to a rate of change of the state of the steering wheel with respect to time,

to calculate a target brake hydraulic pressure according to the traveling condition and the target yawing moment,

to calculate a target driving force according to the traveling condition and the target brake hydraulic pressure, and

to output a first drive signal indicative of the target brake hydraulic pressure to the brake hydraulic pressure control circuit and a second drive signal indicative of the target driving force to the driving force control unit.

10. A method of executing a lane-keep control of a host-vehicle, comprising:

detecting a traveling condition of the host-vehicle;

determining that there is a tendency of a lane deviation that the host-vehicle is deviating from a traveling lane, on the basis of the traveling condition;

calculating a driving/braking force controlled variable of each wheel according to the traveling condition so as to generate a yawing moment directed toward a direction of preventing the lane deviation when there is the tendency of the lane deviation;

detecting a steering state quantity indicative of a quantity of state of a steering wheel;

correcting the driving/braking force controlled variable on the basis of the steering state quantity; and

controlling a driving/braking force of each wheel according to the driving/braking force controlled variable.

11. A lane-keep control system for a host-vehicle, comprising:

traveling condition detecting means for detecting a traveling condition of the host-vehicle;

deviation determining means for determining that there is a tendency of a lane deviation that the host-vehicle is deviating from a traveling lane, on the basis of the traveling condition;

driving/braking force control quantity calculating means for calculating a driving/braking force controlled variable of each wheel according to the traveling condition so as to generate a yawing moment directed toward a direction of preventing the lane deviation when there is the tendency of the lane deviation;

driving/braking force controlling means for controlling a driving/braking force of each wheel according to the driving/braking force controlled variable; and

steering condition quantity detecting means for detecting a steering state quantity indicative of a quantity of state of a steering wheel;

wherein the driving/braking control quantity calculating means comprises driving/braking force controlled-variable correcting means for correcting the driving/braking force controlled variable on the basis of the steering state quantity.