Steering apparatus and control method thereof

A steering apparatus comprising:

• a steering angle zero point detection unit configured to detect a zero point of a steering angle of a steering wheel;
• a history holding unit configured to record a maximum value and a minimum value of the zero point of the steering angle as a zero point maximum value and a zero point minimum value, cancel the recorded zero point maximum value and reset the recorded zero point maximum value when a predetermined period elapses following updating of the zero point maximum value, and cancel the recorded zero point minimum value and reset the recorded zero point minimum value when the predetermined period elapses following updating of the zero point minimum value;
• a characteristic variation determination unit configured to determine that characteristic variation has occurred in a steering transmission system when a difference between the zero point maximum value and the zero point minimum value exceeds a first threshold within the predetermined period;
• and
• a precursor determination unit configured to determine that the steering transmission system is in a precursory condition to characteristic variation when the difference between the zero point maximum value and the zero point minimum value exceeds a second threshold, which is smaller than the first threshold, within the predetermined period,
• wherein, when the steering transmission system is determined by the precursor determination unit to be in the precursory condition to characteristic variation, the characteristic variation determination unit is configured to determine whether or not characteristic variation has occurred in the steering transmission system on the basis of at least one of an amount of increase in the zero point maximum value and an amount of decrease in the zero point minimum value following a point at which the steering transmission system is determined to be in the precursory condition to characteristic variation.