Road surface impact stimulation device of steer-by-wire system

1. A road impact simulating apparatus of a steer-by-wire system, the apparatus comprising a controller configured to:

determine a wheel speed difference value between wheels, and determine a lateral acceleration difference value between an estimated lateral acceleration of a vehicle and a sensed lateral acceleration of the vehicle;

determine whether there is a road impact based on the wheel speed difference value between the wheels; and

determine a reaction force torque according to the road impact based on the lateral acceleration difference value if it is determined as the road impact,

wherein the controller is configured to, if a first wheel speed difference value between the left and right front wheels is greater than or equal to a first reference value, a second wheel speed difference value between the left and right rear wheels is less than or equal to a second reference value, and a third wheel speed difference value between the left front and rear wheels or a fourth wheel speed difference value between the right front and rear wheels is greater than or equal to a third reference value, determine that there is the road impact.

2. The road impact simulating apparatus of the steer-by-wire system of claim 1 , further comprising a driver configured to apply the reaction force torque to a steering wheel.

3. The road impact simulating apparatus of the steer-by-wire system of claim 1 , further comprising:

a wheel speed sensor for detecting wheel speed of the wheel; and

a lateral acceleration sensor for detecting the sensed lateral acceleration,

wherein the controller is configured to determine the estimated lateral acceleration based on a steering angle and a vehicle speed.

4. The road impact simulating apparatus of the steer-by-wire system of claim 1 , wherein the controller is configured to, if a first wheel speed difference value between the left and right front wheels is greater than or equal to a first reference value and a second wheel speed difference value between the left and right rear wheels is less than or equal to a second reference value, determine that there is the road impact.

5. The road impact simulating apparatus of the steer-by-wire system of claim 4 , wherein the controller is configured to, if the controller determines that there is the road impact and a steering torque of a vehicle driver is less than or equal to a fourth reference value or a rack force is less than or equal to a fifth reference value, output a road impact signal.

6. The road impact simulating apparatus of the steer-by-wire system of claim 5 , wherein the controller is configured to receive the road impact signal and determine an active count, which is an application time of the reaction force torque.

7. The road impact simulating apparatus of the steer-by-wire system of claim 6 , wherein the controller is configured to determine the active count based on a wheelbase and a vehicle speed of the vehicle.

8. The road impact simulating apparatus of the steer-by-wire system of claim 1 , wherein the controller is configured to set a reaction force torque map that defines the reaction force torque according to a difference in lateral acceleration for each vehicle speed, and determine the reaction force torque according to the lateral acceleration difference value and the vehicle speed using the reaction force torque map.

9. A road impact simulating method of a steer-by-wire system, the method comprising:

determining a wheel speed difference value between wheels, and determining a lateral acceleration difference value between an estimated lateral acceleration of a vehicle and a sensed lateral acceleration of the vehicle;

determining whether there is a road impact based on the wheel speed difference value;

determining a reaction force torque according to the road impact based on the lateral acceleration difference value if it is determined that there is the road impact; and

if a first wheel speed difference value between the left and right front wheels is greater than or equal to a first reference value, a second wheel speed difference value between the left and right rear wheels is less than or equal to a second reference value, and a third wheel speed difference value between the left front and rear wheels or a fourth wheel speed difference value between the right front and rear wheels is greater than or equal to a third reference value, determining that there is the road impact.

10. The road impact simulating method of the steer-by-wire system of claim 9 , further comprising applying the reaction force torque to a steering wheel.

11. The road impact simulating method of the steer-by-wire system of claim 10 , further comprising:

detecting wheel speed of the wheel;

detecting the sensed lateral acceleration; and

determining the estimated lateral acceleration based on a steering angle and a vehicle speed.

12. The road impact simulating method of the steer-by-wire system of claim 9 , further comprising, if a first wheel speed difference value between the left and right front wheels is greater than or equal to a first reference value and a second wheel speed difference value between the left and right rear wheels is less than or equal to a second reference value, determining that there is the road impact.

13. The road impact simulating method of the steer-by-wire system of claim 12 , wherein further comprising, if it is determined that there is the road impact and a steering torque of a vehicle driver is less than or equal to a fourth reference value or a rack force is less than or equal to a fifth reference value, outputting a road impact signal.

14. The road impact simulating method of the steer-by-wire system of claim 13 , further comprising receiving the road impact, signal and determine an active count, which is an application time of the reaction force torque.

15. The road impact simulating method of the steer-by-wire system of claim 14 , further comprising determining the active count based on a wheelbase and a vehicle speed of the vehicle.

16. The road impact simulating method of the steer-by-wire system of claim 9 , further comprising setting a reaction force torque map that defines the reaction force torque according to a difference in lateral acceleration for each vehicle speed, and determining the reaction force torque according to the lateral acceleration difference value and the vehicle speed using the reaction force torque map.