Driving assist system for vehicle

1. A driving assist system for vehicle comprising:

a state recognition device that detects vehicle conditions of a subject vehicle and a traveling environment for vehicle surroundings;

a risk potential calculator that calculates a risk potential for vehicle surroundings based on detection results of the state recognition device;

a risk change estimator that estimates a change in risk felt by a driver;

a correction device that corrects a calculation equation for calculating the risk potential at the risk potential calculator based on estimation results of the risk change estimator; and

an operation reaction force controller that modifies a reaction force applied to vehicle operation equipment based on the risk potential calculated using the calculation equation corrected by the correction device, to convey information related to the risk potential to the driver via the vehicle operation equipment;

wherein the vehicle operation equipment is used by the driver in operating the vehicle.

2. A driving assist system for vehicle according to claim 1 , wherein:

the risk change estimator estimates change in the risk felt by the driver due to environmental change.

3. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects a state of illumination of brake lamps of a preceding vehicle as the environmental change, and estimates the change in the risk felt by the driver according to the state of illumination of the brake lamps.

4. A driving assist system for vehicle according to claim 1 , wherein:

the correction device corrects the calculation equation for the risk potential by adding a correction value based on the estimation results of the risk change estimator, and

the correction value is smaller than the risk potential calculated by the calculation equation prior to correction.

5. A driving assist system for vehicle according to claim 1 , wherein:

the correction device corrects the calculation equation for the risk potential by adding a correction value based on the estimation results of the risk change estimator, and

the correction value is changed according to the risk potential calculated by the calculation equation prior to correction.

6. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects a plurality of environment change parameters, and

the correction device calculates correction values based on detection results for the plurality of environment change parameters of the risk change estimator, and corrects the calculation equation for the risk potential by adding a largest value among a plurality of correction values thus calculated.

7. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects a traffic flow density as the environmental change, and estimates the change in the risk felt by the driver according to the traffic flow density.

8. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects a road width of a vehicle lane as the environmental change, and estimates the change in the risk felt by the driver according to the road width.

9. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects presence or absence of a neighboring vehicle lane as the environmental change, and estimates the change in the risk felt by the driver according to the presence or absence of the neighboring lane.

10. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects a distance from the subject vehicle to a branching/merging point of a vehicle lane as the environmental change, and estimates the change in the risk felt by the driver according to the distance to the branching /merging point.

11. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects a road gradient as the environmental change, and estimates the change in the risk felt by the driver according to the road gradient.

12. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects a type of a preceding vehicle as the environmental change, and estimates the change in the risk felt by the driver according to the type of the preceding vehicle.

13. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects weather as the environmental change, and estimates the change in the risk felt by the driver according to the weather.

14. A driving assist system for vehicle according to claim 2 , wherein:

the risk change estimator detects an extent of road surface friction of a vehicle lane as the environmental change, and estimates the change in the risk felt by the driver according to the extent of road surface friction.

15. The system of claim 1 , wherein the vehicle operation equipment is an accelerator pedal.

16. A driving assist system for vehicle comprising:

a state recognition means for detecting vehicle conditions of a subject vehicle and a traveling environment for vehicle surroundings;

a risk potential calculation means for calculating a risk potential for vehicle surroundings based on detection results of the state recognition means;

a risk change estimating means for estimating a change in risk felt by a driver;

a correction means for correcting a calculation equation for calculating the risk potential at the risk potential calculation means based on estimation results of the risk change estimating means; and an operation reaction force control means for modiPjing a reaction force applied to vehicle operation equipment based on the risk potential calculated using the calculation equation corrected by the correction means, to convey information related to the risk potential to the driver via the vehicle operation equipment;

wherein the vehicle operation equipment is used by the driver in operating the vehicle.

17. The system of claim 16 , wherein the vehicle operation equipment is an accelerator pedal.

18. A vehicle driving assist method comprising:

detecting vehicle conditions of a subject vehicle and a traveling environment for vehicle surroundings;

calculating a risk potential for vehicle surroundings based on the vehicle conditions and the traveling environment thus detected;

estimating a change in risk felt by a driver;

correcting a calculation equation for calculating the risk potential based on the estimated change in the risk felt by the driver; and

modifying a reaction force applied to vehicle operation equipment based on the risk potential calculated using the calculation equation thus corrected, to convey information related to the risk potential to the driver via the vehicle operation equipment;

wherein the vehicle operation equipment is used by the driver in operating the vehicle.

19. The method of claim 18 , wherein the vehicle operation equipment is an accelerator pedal.

20. A vehicle comprising:

a driving assist system for vehicle that comprises (a) a state recognition device that detects vehicle conditions of a subject vehicle and a traveling environment for vehicle surroundings; (b) a risk potential calculator that calculates a risk potential for vehicle surroundings based on detection results of the state recognition device; (c) a risk change estimator that estimates a change in risk felt by a driver; (d) a correction device that corrects a calculation equation for calculating the risk potential at the risk potential calculator based on estimation results of the risk change estimator; and (e) an operation reaction force controller that modifies a reaction force applied to vehicle operation equipment based on the risk potential calculated using the calculation equation corrected by the correction device, to convey information related to the risk potential to the driver via the vehicle operation equipment;

wherein the vehicle operation equipment is used by the driver in operating the vehicle.

21. The vehicle of claim 20 , wherein the vehicle operation equipment is an accelerator pedal.