Vehicular steering apparatus

A vehicular steering apparatus, comprising:

• a motor for generating an assist torque for supplementing a steering torque exerted by a driver of a vehicle;
• steering shaft reaction torque detecting means for detecting a steering shaft reaction torque generated on a steering shaft of the vehicle and having hysteresis characteristics;
• road surface reaction torque detecting means for detecting a road surface reaction torque received by wheels of the vehicle from a road surface;
• and
• target current calculating means for calculating a target current value for driving the motor, wherein:
• the target current calculating means includes first compensation means for calculating a first compensation amount for compensating for the assist torque based on the steering shaft reaction torque, and second compensation means for calculating a second compensation amount for compensating for the assist torque based on the road surface reaction torque;
• and
• the target current calculating means uses the first and second compensation amounts to calculate the target current to compensate for an overall friction torque generated in an entire steering mechanism of the vehicle and a gradient of the road surface reaction torque,
• wherein the first compensation amount is a friction compensation torque, which acts in a steering direction of a driver and which is calculated based on the steering shaft reaction torque and a speed of the vehicle;
• and
• wherein the second compensation amount is a return compensation torque, which acts in a direction opposite the steering direction of the driver and which is calculated based on the road surface reaction torque and the vehicle speed.