STEERING ASSIST DEVICE

• US 20110251758A1
• Filed: 06/20/2011
• Published: 10/13/2011
• Est. Priority Date: 03/12/2010
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: KATAOKA, Hiroaki
• Granted Patent: US 9,002,579 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• 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

Abstract

A steering assist device capable of appropriately reducing a steering load on a driver is provided. A steering assist device for assisting a steering operation of a driver who drives a vehicle, comprises: an auxiliary torque generation section for causing a steering device of the vehicle to generate an auxiliary torque that assists a steering force of the driver; a first torque control section for controlling the auxiliary torque so as to cause the vehicle to perform turning in accordance with a curvature of a travel lane in which the vehicle travels; a second torque control section for controlling the auxiliary torque so as to bring the position of the vehicle close to a center line of the travel lane; a lane change determination section for determining whether or not the vehicle is performing lane change; and a control suppression section for suppressing the control of the auxiliary torque by the second torque control section when it is determined that the vehicle is performing lane change.

Claims

1. A steering assist device for assisting a steering operation of a driver who drives a vehicle, the device comprising:

an auxiliary torque generation section for causing a steering device of the vehicle to generate an auxiliary torque that assists a steering force of the driver;

a first torque control section for controlling the auxiliary torque so as to cause the vehicle to perform turning in accordance with a curvature of a travel lane in which the vehicle travels;

a second torque control section for controlling the auxiliary torque so as to bring the position of the vehicle close to a center line of the travel lane;

a lane change determination section for determining whether or not the vehicle is performing lane change; and

a control suppression section for suppressing the control of the auxiliary torque by the second torque control section when it is determined that the vehicle is performing lane change.

2. The steering assist device according to claim 1 further comprising:

an imaging section for taking an image in front of the vehicle;

a curvature calculation section for calculating, based on the image, a curvature of the travel lane in which the vehicle travels;

an offset distance calculation section for calculating an offset distance from the center line of the travel lane to the vehicle; and

a deflection angle calculation section for calculating a deflection angle which is formed between a straight line indicating a direction along which the vehicle travels, and the center line of the travel lane, wherein

the first torque control section control the auxiliary torque in accordance with the curvature calculated by the curvature calculation section so as to cause the vehicle to perform turning in accordance with the curvature, and

the second torque control section controls the auxiliary torque in accordance with at least one of the offset distance and the deflection angle so as to bring the position of the vehicle close to the center line of the travel lane.

3. The steering assist device according to either of claims 1 and 2 further comprising:

a lane change direction determination section for determining, when the vehicle is performing lane change, in which direction, left or right, the vehicle performs the lane change; and

an auxiliary torque acting direction determination section for determining in which direction, left or right, the vehicle turns due to the auxiliary torque controlled by the second torque control section, wherein

the control suppression section suppresses the control of the auxiliary torque by the second torque control section only when it is determined that the vehicle is performing lane change, and the direction of lane change does not coincide with the direction of turning.

4. The steering assist device according to claim 1, wherein

the lane change determination section determines that the vehicle is performing lane change when a direction indicator mounted on the vehicle is being operated, and determines that the vehicle is not performing lane change when the direction indicator is not being operated.

5. The steering assist device according to claim 1 further comprising:

a steering torque detection section for detecting a steering torque generated by an operation of the driver of the vehicle, wherein

the lane change determination section determines that the vehicle is performing lane change when the steering torque is equal to or greater than a predetermined steering torque threshold value, and determines that the vehicle is not performing lane change when the steering torque is smaller than the steering torque threshold value.

6. The steering assist device according to claim 5 further comprising:

a steering torque threshold calculation section for calculating the steering torque threshold value in accordance with the curvature of the travel lane in which the vehicle travels.

7. The steering assist device according to claim 1 further comprising:

a steering angle detection section for detecting a steering angle of the vehicle, wherein

the lane change determination section determines that the vehicle is performing lane change when the steering angle is equal to or greater than a predetermined steering angle threshold value, and determines that the vehicle is not performing lane change when the steering angle is smaller than the steering angle threshold value.

8. The steering assist device according to claim 7 further comprising:

a steering angle threshold calculation section for calculating the steering angle threshold value in accordance with the curvature of the travel lane in which the vehicle travels.

9. The steering assist device according to claim 2, wherein

the lane change determination section determines that the vehicle is performing lane change when the offset distance is equal to or longer than a predetermined distance threshold value, and determines that the vehicle is not performing lane change when the offset distance is shorter than the distance threshold value.

10. The steering assist device according to claim 9 further comprising:

a lane width calculation section for calculating the width of the travel lane in which the vehicle travels; and

a threshold calculation section for calculating the distance threshold value in accordance with the width of the travel lane.

11. The steering assist device according to claim 1, wherein

the lane change determination section determines that the vehicle is performing lane change when a hazard lamp mounted on the vehicle is being operated, and determines that the vehicle is not performing lane change when the hazard lamp is not operated.

12. The steering assist device according to claim 2, wherein

the second torque control section controls the auxiliary torque in such a manner that the greater a value obtained by multiplying the offset distance and the deflection angle by predetermined gain values, respectively, is, the greater the auxiliary torque is, and

the control suppression section changes the gain value to a smaller value when it is determined that the vehicle is performing lane change than when it is determined that the vehicle is not performing lane change, and thus suppresses the control of the auxiliary torque by the second torque control section.

13. The steering assist device according to claim 2, wherein

the second torque control section controls the auxiliary torque in such a manner that the greater the offset distance and the deflection angle are, the greater the auxiliary torque is, and

the control suppression section corrects the values of the offset distance and the deflection angle, which are input to the second torque control section, to smaller values when it is determined that the vehicle is performing lane change than when it is determined that the vehicle is not performing lane change, and thus suppresses the control of the auxiliary torque by the second torque control section.