Steering control apparatus and steering control method

A steering control apparatus comprising:

• a first sensing unit configured to sense a steering torque using a torque sensor;
• a high frequency output unit configured to input a steering torque to a high pass filter and output high frequency steering torques in which low frequency steering torques are eliminated;
• a detection unit configured to detect a first frequency corresponding to a maximum steering torque among high frequency steering torques;
• a calculation unit configured to calculate a high frequency steering torque change rate, which is the rate of change in the high frequency steering torques over time;
• a band frequency output unit configured to input the high frequency steering torque change rate to a band pass filter that passes a first frequency band including the first frequency, so as to output a first frequency band steering torque change rate;
• and
• a compensation unit configured to compensate an assist current of a steering motor on the basis of a rejection gain corresponding to the first frequency and the first frequency band steering torque change rate,
• wherein when a frequency has a value of being equal to or smaller than a first frequency threshold value, the rejection gain is defined as a value of “1”, when a frequency has a value exceeding the first frequency threshold value and being equal to or smaller than the second frequency threshold value, the rejection gain is inversely proportional to the frequency and defined as a value between “1” and “0”, and when the frequency exceeds the second frequency threshold value, the rejection gain is defined as a value of “0”,
• wherein the steering control apparatus further comprises:
• a second sensing unit configured to sense a vehicle speed using a vehicle speed sensor, wherein the compensation unit compensates the assist current on the basis of the rejection gain, the first frequency band steering torque change rate, and a speed gain corresponding to the vehicle speed, wherein, when the vehicle speed has a value of being equal to or smaller than a first speed threshold value, the speed gain is defined as a value of “0”, and when the vehicle speed has a value exceeding the first speed threshold value, the speed gain is defined as being proportional to the vehicle speed, and
• wherein the steering control apparatus further comprises:
• a third sensing unit configured to sense a steering angle using an angle sensor, wherein the compensation unit compensates the assist current on the basis of the rejection gain, the first frequency band steering torque change rate, and an angle gain corresponding to the steering angle, wherein, when the steering angle has a value of being equal to or smaller than a first angle threshold value, the angle gain is defined as a value of “1”, when the steering angle has a value exceeding the first angle threshold value and being equal to or smaller than a second angle threshold value, the angle gain is inversely proportional to the frequency and defined as a value between “1” and “0”, and when the steering angle has a value exceeding the second angle threshold value, the angle gain is defined as a value of “0”.