Steering apparatus for vehicle and method therefor

A processor-implemented method of controlling a steering device of a vehicle, the method comprising:

• monitoring failure of an electric steering system;
• calculating a target yaw rate value and a target velocity value of the vehicle based on signals received from one or more of an acceleration pedal stroke sensor, a brake pedal stroke sensor, a steering angle sensor, and a steering torque sensor, in response to detecting the failure in the electric steering system;
• detecting a wheel angle of a front wheel portion of the vehicle;
• performing backup steering based on generating slip in the vehicle to move the vehicle in a direction corresponding to an intended direction;
• and
• controlling a velocity of the vehicle so that the vehicle is driven based on an intended velocity,
• wherein the performing of the backup steering comprises
• calculating a braking torque for each of the front wheel portion and a rear wheel portion based on the velocity of the vehicle and a steering angle of the vehicle, and
• distributing the braking torque to the front wheel portion and the rear wheel portion,
• wherein the distributing of the braking torque comprises:
• distributing and applying the braking torque to the front wheel portion and the rear wheel portion with a distribution ratio that varies according to a required steering angle to compensate for a total yaw moment value of the vehicle proportional to the steering angle,
• applying the braking torque to the rear wheel portion to compensate for the total yaw moment value, in response to the steering angle being 20° or less, and
• first applying the braking torque to the rear wheel portion and after applying the braking torque to the rear wheel portion, applying the braking torque to the front wheel portion to compensate for the total yaw moment value, in response to the steering angle being 50° or greater.