Steering torque compensating apparatus and steering torque compensating method

1. A steering torque compensating apparatus, comprising:

a reference object recognition unit that recognizes a fixed reference object arranged in correspondence to a lane of a road by using a camera of a vehicle;

a distance measurement unit that measures a distance difference between the vehicle and the fixed reference object;

an operation determination unit that calculates a distance change rate that is a change rate of the distance difference per time and determines whether the vehicle is driven forwards or rearwards, by using the distance change rate; and

a controller that controls an assistance steering torque,

wherein the controller

sets the assistance steering torque to a target torque when it is determined that the vehicle is driven forwards,

sets magnitude of the assistance steering torque to magnitude of the target torque, and

sets a direction of the assistance steering torque to a direction opposite to the direction of the target torque when it is determined that the vehicle is driven rearwards.

2. The steering torque compensating apparatus of claim 1 , wherein the fixed reference object is one of opposite lines of the lane, and the corresponding line of the lane is determined according to a heading angle of the vehicle.

3. The steering torque compensating apparatus of claim 1 , wherein the operation determination unit determines that the vehicle is driven forwards if the distance change rate is calculated as being a negative value, and determines that the vehicle is driven rearwards if the distance change rate is calculated as being a positive value.

4. The steering torque compensating apparatus of claim 1 , further comprising:

a speed calculation unit that measures a longitudinal speed by using a speed sensor of the vehicle; and

an angle calculation unit that calculates an angle between a forward direction of the vehicle and the line of the lane,

wherein the operation determination unit determines whether the vehicle is driven forwards or rearwards by using the distance change rate when the magnitude of the distance change rate corresponds to a product, within a preset error range, of the longitudinal speed and the angle.

5. The steering torque compensating apparatus of claim 1 , wherein the operation determination unit continuously calculates a distance change rate for a predetermined time period after the vehicle is driven forwards or rearwards.

6. The steering torque compensating apparatus of claim 1 , further comprising:

a speed calculation unit that measures a longitudinal speed by using a speed sensor of the vehicle,

wherein the operation determination unit determines an operation of the vehicle again if the longitudinal speed is zero.

7. The steering torque compensating apparatus of claim 1 , wherein the target torque is a steering assisting torque that makes the vehicle parallel to the line of the lane.

8. A steering torque compensating method, comprising:

recognizing a fixed reference object arranged in correspondence to a lane of a road by using a camera of a vehicle;

measuring a distance difference between the vehicle and the fixed reference object;

calculating a distance change rate that is a change rate of the distance difference per time and determining whether the vehicle is driven forwards or rearwards, by using the distance change rate;

setting an assistance steering torque to a target torque when it is determined that the vehicle is driven forwards, and setting a magnitude of the assistance steering torque to magnitude of the target torque; and

setting a direction of the assistance steering torque to a direction opposite to the direction of the target torque when it is determined that the vehicle is driven rearwards.

9. The steering torque compensating method of claim 8 , wherein the fixed reference object is one of opposite lines of the lane, and the corresponding line of the lane is determined according to a heading angle of the vehicle.