VEHICLE BEHAVIOR CONTROL APPARATUS

• US 20130131925A1
• Filed: 11/14/2012
• Published: 05/23/2013
• Est. Priority Date: 11/18/2011
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Isaji, Kazuyoshi, Tsuru, Naohiko, Morikawa, Shou
• Granted Patent: US 8,855,860 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B60K 31/0066 responsive to vehicle path curvature
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 2552/30 Road curve radius
• CPC Class Codes: B60W 2554/801 Lateral distance
• CPC Class Codes: B60W 2556/65 Data transmitted between vehicles
• CPC Class Codes: B60W 30/10 Path keeping cruise control for automatically following a preceding vehicle B60W30/165
• CPC Class Codes: B60W 30/16 Control of distance between vehicles, e.g. keeping a distance to preceding vehicle
• CPC Class Codes: B60W 30/18145 Cornering
• CPC Class Codes: B62D 6/00 Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00

Abstract

A vehicle behavior control apparatus disposed in a subject vehicle performs a steering angle control of the subject vehicle. The apparatus acquires lead vehicle information transmitted from a lead vehicle to determine a virtual shape of a road (i.e., a virtual road shape) based on a travel locus of the lead vehicle. A virtual road border distance is calculated as a distance from the subject vehicle to a road border of a virtual curve road positioned straight in front of the subject vehicle. The apparatus, calculates an appropriate turn radius for travel along the virtual curve road and, based on the appropriate turn radius, calculates an appropriate distance from the subject vehicle to the virtual road border positioned in front of the subject vehicle. A steering unit then controls a steering angle of the subject vehicle by maintaining the virtual road border distance with the appropriate distance.

Claims

1. A vehicle behavior control apparatus disposed in a subject vehicle and including a wireless communication apparatus for exchanging information through vehicle to vehicle communication, the vehicle behavior control apparatus comprising:

a current position acquisition unit regularly acquiring a current position of the subject vehicle;

a lead vehicle information acquisition unit acquiring lead vehicle information via the wireless communication apparatus, the lead vehicle information being regularly transmitted from a lead vehicle;

a virtual road shape determination unit determining a virtual shape of a road as a virtual road shape based on the lead vehicle information;

a virtual road border distance calculation unit calculating a virtual road border distance as a distance from the subject vehicle to a road border of a virtual curve road straight in front of the subject vehicle based on the current position of the subject vehicle and the virtual road shape;

a curvature radius calculation unit calculating a curvature radius of the virtual curve road in front of the subject vehicle based on the virtual road shape;

a turn radius calculation unit calculating an appropriate turn radius of the subject vehicle for a travel of the virtual curve road based on the curvature radius calculated by the curvature radius calculation unit;

an appropriate distance calculation unit calculating an appropriate distance within the virtual curve road from the subject vehicle to the road border straight in front of the subject vehicle based on the appropriate turn radius; and

a steering unit performing a steering angle control of the subject vehicle by controlling a steering angle of the subject vehicle traveling along the virtual curve road such that the virtual road border distance equals the appropriate distance.

2. The vehicle behavior control apparatus of claim 1 further comprising:

an entrance determination unit determining an entrance position of the virtual curve road based on the lead vehicle information acquired by the lead vehicle information acquisition unit, the lead vehicle information including at least one of a steering angle and an inside-outside tire speed ratio of the lead vehicle;

a steering start point determination unit determining a steering start point according to the virtual road border distance in a straight road part leading to the entrance position;

an entrance area start point determination unit determining a position being apart from the steering start point by a predetermined distance in a front direction of the subject vehicle, as an entrance area start point of a curve entrance shift area between the steering start point and a preset point; and

an entrance area virtual curve set unit setting an entrance area virtual curve in order for a travel locus of the subject vehicle to draw a relaxation curve according to the steering angle control by the steering unit, wherein,

when the steering angle control by the steering unit is performed based on the appropriate distance from the subject vehicle to the entrance area virtual curve straight in front of the subject vehicle, the entrance area virtual curve is determined as a curve between (i) the entrance area start point determined by the entrance area start point determination unit and (ii) a preset end point on the virtual road border in the curve entrance shift area, and

the appropriate distance calculation unit calculates, as the appropriate distance, a distance from the subject vehicle to the entrance area start point virtual curve straight in front of the subject vehicle while the subject vehicle is traveling along the curve entrance shift area.

3. The vehicle behavior control apparatus of claim 2 further comprising:

a steering start evaluation index calculation unit calculating a steering start evaluation index KdB_e, the steering start evaluation index KdB_e representing a state of changing distance from the subject vehicle to the virtual road border in consideration of an approach speed of the subject vehicle toward the virtual road border, the index KdB_e increasing as the approaching speed of the subject vehicle toward the virtual road border increases, and an increase curve of the index KdB_e becoming steeper per unit change of decrease of the virtual road border distance as the virtual road border distance decreases;

a steering start determination unit determining whether a current value KdB_e_p of the steering start evaluation index KdB_e exceeds a threshold KdB_e_str of the steering start evaluation index KdB_e being determined based on the distance of the virtual road border straight in front of the subject vehicle; and

a steering start unit starting the steering of the subject vehicle when the current value KdB_e_p of the steering start evaluation index KdB_e exceeds the threshold KdB_e_str, wherein

the steering start point determination unit determines, as the steering start point, the current position of the subject vehicle when the current value KdB_e_p of the steering start evaluation index KdB_e exceeds the threshold KdB_e_str.

4. The vehicle behavior control apparatus of claim 3, wherein

the steering start evaluation index KdB_e and the threshold KdB_e_str of the steering start evaluation index KdB_e are respectively calculated by:

5. The vehicle behavior control apparatus of claim 1 further comprising:

an exit determination unit determining an exit position of the virtual curve road based on at least one of a steering angle and a inside-outside tire speed ratio of the lead vehicle acquired by the lead vehicle information acquisition unit;

a steering return operation start point determination unit determining, as a steering return operation start point, a position of the subject vehicle viewing an intersection between (i) the virtual road border of the virtual curve road and (ii) the virtual road border of the straight road part after the exit position of the virtual curve road;

a steering end point determination unit determining, as a steering end point, the exit position determined by the exit determination unit;

an exit area start point determination unit determining the intersection determined by the steering return operation start point determination unit as an exit area start point;

an exit area end point determination unit determining, as an exit area end point in a curve exit shift area between the steering return operation start point and the exit position, a point apart from the exit position on a centerline between the virtual road border on both sides of the straight road part after the exit position of the curve, the point on the centerline defined according to the speed of the subject vehicle;

an exit area virtual curve set unit setting an exit area virtual curve in order for a travel locus of the subject vehicle to draw a relaxation curve according to the steering angle control by the steering unit, when the steering angle control by the steering unit is performed based on the appropriate distance from the subject vehicle to the exit area virtual curve straight in front of the subject vehicle, the exit area virtual curve being determined as a curve between (i) the exit area start point determined by the exit area start point determination unit and (ii) the exit area end point determined by the exit area end point determination unit, wherein

the appropriate distance calculation unit calculates, as the appropriate distance, a distance from the subject vehicle to the exit area virtual curve straight in front of the subject vehicle while the subject vehicle is traveling along the curve exit shift area.

6. The vehicle behavior control apparatus of claim 1 further comprising:

a tire steer angle calculation unit calculating a tire steer angle θ

for maintaining the virtual road border distance with the appropriate distance; and

a steering angle calculation unit calculating a steering angle Θ

according to the tire steer angle θ

, wherein

the steering unit uses the steering angle Θ

as a target of the steering angle control.

7. The vehicle behavior control apparatus of claim 6, wherein

the tire steer angle calculation unit calculates the tire steer angle θ

and an estimated outside curvature radius Ra that is calculated from the appropriate distance from the appropriate distance calculation unit,

the steering angle calculation unit calculates a target steering angle Θ

based on the tire steer angle θ

, and

the tire steer angle θ

, the estimated outside curvature radius Ra, and the target steering angle Θ

are calculated according to equations;

8. The vehicle behavior control apparatus of claim 1 further comprising:

a steering angle correction unit correcting the steering angle Θ

to steer the subject vehicle toward a center of the virtual road borders of the straight road part, the straight road part being defined as (i) the straight road part outside of the virtual curve road when the subject vehicle is located on a straight road part that is outside of the virtual curve road or as (ii) the straight road part that is virtually set as a tangent line of the virtual curve road when the subject vehicle is located in the virtual curve road, wherein

the steering unit performs the steering angle control, using the steering angle Θ

calculated by the steering angle correction unit as the target steering angle, and

the steering angle correction unit corrects the steering angle Θ

by using equations;

9. The vehicle behavior control apparatus of claim 1 further comprising:

a followee object determination unit determining a vehicle capable of performing vehicle-to-vehicle communication as a followee object to be followed by the subject vehicle, wherein

the followee object is the lead vehicle from which the lead vehicle information is acquired by the lead vehicle information acquisition unit, and

the steering unit performs a follow travel control for following the followee object that is determined by the followee object determination unit.

10. The vehicle behavior control apparatus of claim 9 further comprising:

an entrance determination unit determining an entrance position of the virtual curve road based on at least one of a steering angle of the lead vehicle and an inside-outside tire speed ratio of the lead vehicle acquired as the lead vehicle information by the lead vehicle information acquisition unit;

a speed acquisition unit regularly acquiring a speed of the subject vehicle;

an inter-vehicle distance detection unit detecting an inter-vehicle distance between the lead vehicle and the subject vehicle;

a lead vehicle relative speed calculation unit regularly calculating a relative speed of the lead vehicle relative to the subject vehicle, based on the speed of the subject vehicle and the speed of the lead vehicle;

a first evaluation index calculation unit calculating a first corrected evaluation index representing a state of changing distance between the subject vehicle and the lead vehicle in consideration of the speed of the lead vehicle, the first corrected evaluation index increasing as the relative speed for approaching the lead vehicle increases and as the inter-vehicle distance to the lead vehicle decreases, wherein an increase curve of the first corrected evaluation index becomes steeper per unit change of decrease of the inter-vehicle distance as the inter-vehicle distance decreases;

a first deceleration target determination unit determining whether the first corrected evaluation index exceeds a first deceleration threshold having a preset value;

an adaptive deceleration calculation unit calculating a required deceleration for maintaining an actual relative speed relative to the lead vehicle with a first target relative speed being determined based on the first corrected evaluation index and the inter-vehicle distance to the lead vehicle when the first deceleration target determination unit determines that the first corrected evaluation index exceeds the first deceleration threshold;

an entrance distance calculation unit calculating a distance from the current position of the subject vehicle acquired by the current position acquisition unit to the entrance position determined by the entrance determination unit;

a target curving speed set unit setting a target curving speed of the subject vehicle for a travel of the virtual curve road based on the outside curvature radius calculated by the curvature radius calculation unit and a target side acceleration of the subject vehicle having a preset value;

a curve entrance relative speed calculation unit calculating a curve entrance relative speed as a difference between the target curving speed and the speed of the subject vehicle;

a second evaluation index calculation unit calculating a second corrected evaluation index representing a state of changing distance from the subject vehicle to the entrance position of the curve road in consideration of the target curving speed for passing the entrance of the curve road, the second corrected evaluation index increasing as the curve entrance relative speed increases, wherein an increase curve of the second corrected evaluation index becomes steeper as the distance to the entrance position of the curve road decreases;

a deceleration start determination unit determining whether the second corrected evaluation index exceeds a second deceleration threshold having a preset value;

a curve road deceleration calculation unit calculating a required deceleration for maintaining an actual curve entrance relative speed with a second target relative speed when the deceleration start determination unit determines that the second corrected evaluation index exceeds the second deceleration threshold, wherein the second target relative speed is determined based on the second corrected evaluation index and the distance to the entrance position of the curve road; and

a comparison unit comparing the required deceleration calculated by the adaptive deceleration calculation unit with the required deceleration calculated by the curve road deceleration calculation unit when the adaptive deceleration calculation unit and the curve road deceleration calculation unit have respectively calculated the required deceleration, wherein a required deceleration having a greater absolute value is output from among two required decelerations from respective calculation units.

11. The vehicle behavior control apparatus of claim 10 further comprising:

a first acceleration target determination unit determining whether the first corrected evaluation index calculated by the first corrected evaluation index calculation unit is smaller than a first acceleration threshold having a preset value;

an adaptive acceleration calculation unit calculating a required acceleration for maintaining an actual relative speed relative to the lead vehicle with the first target relative speed when the first acceleration target determination unit determines that the first corrected evaluation index is smaller than the first deceleration threshold;

a curving determination unit determining whether the subject vehicle has entered the virtual curve road based on the entrance position determined by the entrance determination unit and the current position of the subject vehicle acquired by the current position acquisition unit;

a curve border relative speed calculation unit calculating a curve border relative speed as a difference between the subject vehicle speed and the target curving speed based on the subject vehicle speed acquired by the speed acquisition unit, the target curving speed set by the target curving speed set unit for a travel of the curve road;

a third evaluation index calculation unit calculating a third corrected evaluation index as an index that represents a state of changing distance from the subject vehicle to the road border of the virtual curve road in consideration of the target curving speed for traveling the curve road, the third corrected evaluation index increasing as the road border relative speed increases, and an increase curve (i.e., a slope) of the third corrected evaluation index becoming steeper as a distance calculated as a result of subtraction of the appropriate distance from the virtual road border distance decreases;

a second deceleration target determination unit determining whether the third corrected evaluation index calculated exceeds a third deceleration threshold having a preset value;

a second acceleration target determination unit for determining whether the third corrected evaluation index exceeds a second acceleration threshold having a preset value;

an in-curve acceleration calculation unit calculating a required acceleration for maintaining an actual curve border relative speed with a third target relative speed being determined based on the third corrected evaluation index and the distance calculated by subtracting the appropriate distance from virtual road border distance when (i) the curving determination unit determines that the subject vehicle has entered the virtual curve road and (ii) the second acceleration target determination unit determines that the third corrected evaluation index has a value that is smaller than the second acceleration threshold, wherein

the curve road deceleration calculation unit calculates a required deceleration that maintains the curve entrance relative speed with a target value that is determined based on the second corrected evaluation index and the distance to the entrance position when (i) the curving determination unit has determined that the subject vehicle has not entered the virtual curve road and (ii) the deceleration start determination unit has determined that the second corrected evaluation index exceeds the second deceleration threshold,

the curve road deceleration calculation unit calculates a required deceleration that maintains the actual curve border relative speed with a target value that is determined based on the third corrected evaluation index and a distance calculated by subtracting the appropriate border distance from the virtual road border distance when (i) the curving determination unit has determined that the subject vehicle has entered the virtual curve road and (ii) the second deceleration target determination unit has determined that the third corrected evaluation index exceeds the third deceleration threshold,

the comparison unit compares the required deceleration calculated by the adaptive deceleration calculation unit with the required deceleration calculated by the curve road deceleration calculation unit when the adaptive deceleration calculation unit and the curve road deceleration calculation unit have respectively calculated the required deceleration,

the comparison unit compares the required acceleration calculated by the adaptive acceleration calculation unit with the required acceleration calculated by the in-curve acceleration calculation unit when the adaptive acceleration calculation unit and the in-curve acceleration calculation unit have respectively calculated the required acceleration,

a required acceleration having a smaller absolute value is output from among two required accelerations from respective calculation units, and

a required deceleration having the greater absolute value is output from among two required decelerations from respective calculation units.

12. The vehicle behavior control apparatus of claim 1 further comprising:

a travel locus determination unit determining a travel locus of the lead vehicle based on at least one of a vehicle speed, a steering angle, and a inside-outside tire speed ratio of the lead vehicle, acquired by the lead vehicle information acquisition unit as the lead vehicle information, wherein

the virtual road shape determination unit determines the virtual road shape based on the travel locus of the lead vehicle determined by the travel locus determination unit.