Driving support device for vehicle including an electric power steering control that generates a steering assist torque

1. A driving support device for a vehicle, comprising:

a steering angle detection device configured to detect a steering angle (θ);

a steering torque detection device configured to detect a steering torque (T);

a driving support control device configured to calculate a target steering angle (θt) corresponding to target steering angles of steered wheels of the vehicle for allowing the vehicle to travel along a target course;

an electric power steering device configured to generate a steering assist torque (Ta); and

an electric power steering control device for controlling the electric power steering device, the electric power steering control device configured to calculate a target driving support torque (Tdt) for causing the steering angle (θ) to attain the target steering angle (θt), to thereby control the electric power steering device so that a driving support torque (Td) attains the target driving support torque (Tdt),

wherein the electric power steering control device is configured to:

set, as a reference steering angle (θs), one of the target steering angle (θt) and the steering angle (θ) acquired when a magnitude of a difference (θ−θt) between the steering angle (θ) and the target steering angle (θt) is estimated to be less than a reference value (θ0);

calculate a corrected steering angle (θ−θs) by subtracting the reference steering angle (θs) from the steering angle (θ);

calculate an indication value (Idsi) indicating an intention of a driver's steering operation, which is correlated to at least one of a first product ((θ−θs)*T) of the corrected steering angle (θ−θs) and the steering torque (T), a second product (dθ*T) of a time derivative (dθ) of the corrected steering angle (θ−θs) and the steering torque (T), and a third product ((θ−θs)*dT) of the corrected steering angle (θ−θs) and a time derivative (dT) of the steering torque (T); and

correct the target steering angle (θt) based on the indication value (Idsi) so that the target driving support torque (Tdt) is corrected in accordance with the intention of the driver's steering operation.

2. The driving support device for a vehicle according to claim 1 , wherein the electric power steering control device is configured to:

calculate, based on the indication value (Idsi), a correction amount (Δθt) of the target steering angle (θt) for correcting the target driving support torque (Tdt) in accordance with the intention of the driver's steering operation; and

calculate the target driving support torque (Tdt) based on a target steering angle (θta) acquired by correcting the target steering angle (θt) with the correction amount (Δθt).

3. The driving support device for a vehicle according to claim 1 , wherein the indication value (Idsi) comprises a weighted sum of at least two of the first product ((θ−θs)*T), the second product (dθ*T), and the third product ((θ−θs)*dT).

4. The driving support device for a vehicle according to claim 1 , wherein the electric power steering control device is configured to:

estimate an insufficient driving support torque (Tds), which corresponds to a difference between a driving support torque (Treq) required for allowing the vehicle to travel along the target course and an actual driving support torque (Td) having a magnitude of the driving support torque (Treq) or less; and

calculate at least one of a corrected first product ((θ−θs)(T−Tds)), a corrected second product (dθ*(T−Tds)), and a corrected third product ((θ−θs)*dT) as alternative values for the first product, the second product, and the third product, respectively, based on a corrected steering torque (T−Tds) and the corrected steering angle (θ−θs), the corrected steering torque (T−Tds) being acquired by subtracting the insufficient driving support torque (Tds) from the steering torque (T).

5. The driving support device for a vehicle according to claim 1 , wherein the electric power steering control device is configured to calculate, as an alternative value for the first product ((θ−θs)*T), a weighted sum of values acquired by integrating each of the second product (dθ*T) and the third product ((θ−θs)*dT) for a time period from a time at which the magnitude of the difference (θ−θt) between the steering angles is estimated to be less than the reference value (θ0) to a current time.

6. The driving support device for a vehicle according to claim 4 , wherein the electric power steering control device is configured to calculate, as an alternative value for the corrected first product ((θ−θs)(T−Tds)), a weighted sum of values acquired by integrating each of the corrected second product (dθ*(T−Tds)) and the corrected third product ((θ−θs)*dT) for a time period from a time at which the magnitude of the difference (θ−θt) between the steering angles is estimated to be less than the reference value (θ0) to a current time.

7. The driving support device for a vehicle according to claim 1 , wherein the electric power steering control device is configured to set, as the reference steering angle (θs), one of the target steering angle (θt) and the steering angle (θ) acquired when a situation in which the magnitude of the difference (θ−θt) between the steering angles is estimated to be less than the reference value (θ0) has continued for a predetermined time period or more.

8. The driving support device for a vehicle according to claim 4 , wherein the electric power steering control device is configured to set, as the reference steering angle (θs), one of the target steering angle (θt) and the steering angle (θ) acquired when a situation in which the magnitude of the difference (θ−θt) between the steering angles is estimated to be less than the reference value (θ0) and a magnitude of the difference (T−Tds) between the steering torque (T) and the insufficient driving support torque (Tds) is estimated to be less than a reference value (T0) has continued for a predetermined time period or more.

9. The driving support device for a vehicle according to claim 1 , wherein the electric power steering control device is configured to limit a magnitude of a time rate of change (dθs) of the reference steering angle (θs) to a limit rate of change (dθs0) or less.

10. A driving support device for a vehicle, comprising:

a steering angle detection device configured to detect a steering angle (θ);

a steering torque detection device configured to detect a steering torque (T);

a driving support control device configured to calculate a target steering angle (θt) corresponding to target steering angles of steered wheels of the vehicle for allowing the vehicle to travel along a target course;

an electric power steering device configured to generate a steering assist torque (Ta); and

an electric power steering control device for controlling the electric power steering device, the electric power steering control device configured to calculate a target driving support torque (Tdt) for causing the steering angle (θ) to attain the target steering angle (θt), to thereby control the electric power steering device so that a driving support torque (Td) attains the target driving support torque (Tdt),

wherein the electric power steering control device is configured to:

set, as a reference steering angle (θs), one of the target steering angle (θt) and the steering angle (θ) acquired when a magnitude of a difference (θ−θt) between the steering angle (θ) and the target steering angle (θt) is estimated to be less than a reference value (θ0);

calculate a corrected steering angle (θ−θs) by subtracting the reference steering angle (θs) from the steering angle (θ);

calculate an indication value (Idsi) indicating an intention of a driver's steering operation, which is correlated to at least one of a first weighted product (G1*Pr1) of a first weight coefficient (G1) and a first product ((θ−θs)*T) of the corrected steering angle (θ−θs) and the steering torque (T), a second weighted product (G2*Pr2) of a second weight coefficient (G2) and a second product (dθ*T) of a time derivative (dθ) of the corrected steering angle (θ−θs) and the steering torque (T), and a third weighted product (G3*Pr3) of a third weight coefficient (G3) and a third product ((θ−θs)*dT) of the corrected steering angle (θ−θs) and a time derivative (dT) of the steering torque (T); and

correct the target steering angle (θt) based on the indication value (Idsi) so that the target driving support torque (Tdt) is corrected in accordance with the intention of the driver's steering operation.

11. The driving support device for a vehicle according to claim 10 , wherein the indication value (Idsi) is correlated to a sum of the first weighted product (G1*Pr1), the second weighted product (G2*Pr2), and the third weighted product (G3*Pr3).

12. A method of controlling a trajectory of a vehicle, the method comprising:

detecting a steering angle (θ) using a steering angle detection device;

detecting a steering torque (T) using a steering torque detection device;

calculating a target steering angle (θt) using a driving support control device, the target steering angle (θt) corresponding to target steering angles of steered wheels of the vehicle for allowing the vehicle to travel along a target course;

generating a steering assist torque (Ta) using an electric power steering device;

calculating a target driving support torque (Tdt) using an electric power steering control device;

controlling the electric power steering device using the electric power steering control device so that a driving support torque (Td) attains the target driving support torque (Tdt) thereby causing the steering angle (θ) to attain the target steering angle (θt); and

causing the electric power steering control device to:

set, as a reference steering angle (θs), one of the target steering angle (θt) and the steering angle (θ) acquired when a magnitude of a difference (θ−θt) between the steering angle (θ) and the target steering angle (θt) is estimated to be less than a reference value (θ0);

calculate a corrected steering angle (θ−θs) by subtracting the reference steering angle (θs) from the steering angle (θ);

calculate an indication value (Idsi) indicating an intention of a driver's steering operation, which is correlated to at least one of a first product ((θ−θs)*T) of the corrected steering angle (θ−θs) and the steering torque (T), a second product (dθ*T) of a time derivative (dθ) of the corrected steering angle (θ−θs) and the steering torque (T), or a third product ((θ−θs)*dT) of the corrected steering angle (θ−θs) and a time derivative (dT) of the steering torque (T); and

correct the target steering angle (θt) based on the indication value (Idsi) so that the target driving support torque (Tdt) is corrected in accordance with the intention of the driver's steering operation.

13. The method of controlling a trajectory of a vehicle according to claim 12 , further comprising causing the electric power steering control device to:

calculate, based on the indication value (Idsi), a correction amount (Δθt) of the target steering angle (θt) for correcting the target driving support torque (Tdt) in accordance with the intention of the driver's steering operation; and

calculate the target driving support torque (Tdt) based on a target steering angle (θta) acquired by correcting the target steering angle (θt) with the correction amount (Δθt).

14. The method of controlling a trajectory of a vehicle according to claim 12 , wherein the indication value (Idsi) comprises a weighted sum of at least two of the first product ((θ−θs)*T), the second product (dθ*T), and the third product ((θ−θs)*dT).

15. The method of controlling a trajectory of a vehicle according to claim 12 , further comprising causing the electric power steering control device to:

estimate an insufficient driving support torque (Tds), which corresponds to a difference between a driving support torque (Treq) required for allowing the vehicle to travel along the target course and an actual driving support torque (Td) having a magnitude of the driving support torque (Treq) or less; and

calculate at least one of a corrected first product ((θ−θs)(T−Tds)), a corrected second product (dθ*(T−Tds)), and a corrected third product ((θ−θs)*dT) as alternative values for the first product ((θ−θs)*T), the second product (dθ*T), and the third product ((θ−θs)*dT), respectively, based on a corrected steering torque (T−Tds) and the corrected steering angle (θ−θs), the corrected steering torque (T−Tds) being acquired by subtracting the insufficient driving support torque (Tds) from the steering torque (T).

16. The method of controlling a trajectory of a vehicle according to claim 15 , further comprising causing the electric power steering control device to calculate, as an alternative value for the corrected first product ((θ−θs)(T−Tds)), a weighted sum of values acquired by integrating each of the corrected second product (dθ*(T−Tds)) and the corrected third product ((θ−θs)*dT) for a time period from a time at which the magnitude of the difference (θ−θt) between the steering angles is estimated to be less than the reference value (θ0) to a current time.

17. The method of controlling a trajectory of a vehicle according to claim 15 , wherein based upon the magnitude of the difference (θ−θt) between the steering angle (θ) and the target steering angle (θt) being estimated to be less than the reference value (θ0) for a predetermined time period or more and also upon a magnitude of the difference (T−Tds) between the steering torque (T) and the insufficient driving support torque (Tds) being estimated to be less than a reference value (T0) for the predetermined time period or more, causing the electric power steering control device to set, as the reference steering angle (θs), one of the target steering angle (θt) and the steering angle (θ).

18. The method of controlling a trajectory of a vehicle according to claim 12 , further comprising causing the electric power steering control device to calculate, as an alternative value for the first product ((θ−θs)*T), a weighted sum of values acquired by integrating each of the second product (dθ*T) and the third product ((θ−θs)*dT) for a time period from a time at which the magnitude of the difference (θ−θt) between the steering angles is estimated to be less than the reference value (θ0) to a current time.

19. The method of controlling a trajectory of a vehicle according to claim 12 , wherein based upon the magnitude of the difference (θ−θt) between the steering angle (θ) and the target steering angle (θt) being estimated to be less than the reference value (θ0) for a predetermined time period or more, causing the electric power steering control device to set, as the reference steering angle (θs), one of the target steering angle (θt) and the steering angle (θ).

20. The method of controlling a trajectory of a vehicle according to claim 12 , further comprising causing the electric power steering control device to limit a magnitude of a time rate of change (dθs) of the reference steering angle (θs) to a limit rate of change (dθs0) or less.