Driving support control apparatus for vehicle

1. A driving support control apparatus for a vehicle that is equipped with a steering assist mechanism and a braking/driving force distribution mechanism for right and left wheels, comprising:

a vehicle motion index value acquisition portion that acquires a vehicle motion index value as an index value of a motion state of the vehicle;

a driving state index value acquisition portion that acquires a driving state index value as an index value of a driving state of a driver of the vehicle;

a driver driving characteristic value estimation portion that estimates a driver driving characteristic value representing driving characteristics of the driver, based on the vehicle motion index value and the driving state index value;

a vehicle motion/driving state target value determination portion that determines a vehicle motion target value as a target value of the vehicle motion index value and a driving state target value as a target value of the driving state index value in driving support control, regardless of the driver's steering;

a control target value determination portion that determines a target value of a steering assist torque and a target value of a difference in braking/driving force between the right and left wheels that converge at least one of a difference between the vehicle motion target value and the vehicle motion index value and a difference between the driving state target value and the driving state index value, using a vehicle motion characteristic value representing motion characteristics of the vehicle, the driver driving characteristic value, the vehicle motion index value and the driving state index value;

a steering assist torque control portion that controls a steering assist torque that is given by the steering assist mechanism, to the target value of the steering assist torque; and

a right/left braking/driving force difference control portion that controls a difference in braking/driving force between the right and left wheels that is given by the braking/driving force distribution mechanism for the right and left wheels, to the target value of the difference in braking/driving force between the right and left wheels.

2. The apparatus according to claim 1 , wherein

the control target value determination portion includes

a feedback gain calculation portion that calculates a feedback gain that converges at least one of the difference between the vehicle motion target value and the vehicle motion index value and the difference between the driving state target value and the driving state index value, using a theory of an optimal regulator, from an equation of state representing the motion state of the vehicle and the driving state of the driver, which is obtained by making respective equations of motion in a lateral direction of the vehicle, a yaw direction of the vehicle and a rotational direction of steered wheels that are represented using the vehicle motion characteristic value, and also an equation of state that gives a steering torque of the driver that is represented using the estimated driver driving characteristic value, simultaneous with one another, and

a control target value calculation portion that calculates the target value of the steering assist torque and the target value of the difference in braking/driving force between the right and left wheels, using at least one of the difference between the vehicle motion target value and the vehicle motion index value and the difference between the driving state target value and the driving state index value, and the feedback gain.

3. The apparatus according to claim 2 , wherein

the feedback gain calculation portion updates the feedback gain using the most recently estimated driver driving characteristic value, when a predetermined condition is fulfilled.

4. The apparatus according to claim 3 , wherein

the feedback gain calculation portion carries out update of the feedback gain when an evaluation function that increases/decreases as a magnitude of a difference between the estimated driver driving characteristic value and a normative driver driving characteristic value as a driver driving characteristic value of a corresponding normative driver model increases/decreases, deviates from a predetermined range.

5. The apparatus according to claim 4 , wherein

the evaluation function is a function of a difference between the estimated driver driving characteristic value and the normative driver driving characteristic value, and further increases/decreases based on a driving history of the driver and the driving characteristics of the driver and/or information on a periphery of the vehicle.

6. The apparatus according to claim 4 , further comprising:

an awareness promotion portion that carries out promotion of awareness of the driver when a number of times the feedback gain is updated exceeds a predetermined number of times.

7. The apparatus according to claim 1 , wherein

the vehicle motion target value and the driving state target value are a vehicle motion index value and a driving state target value that are calculated on an assumption that a target displacement of the vehicle, which is determined based on information on a periphery of the vehicle or a target course of the vehicle, is realized by a normative driver model, respectively.