Control apparatus and method of motor driven power steering system

A control apparatus of a motor driven power steering (MDPS) system, comprising:

• a basic MDPS logic device configured to determine and output a motor control value for steering assistance using driver steering input information and vehicle state information that are collected from a vehicle;
• a state determination device configured to determine whether a steering wheel is currently in a steering state or a restoration state based on the driver steering input information, and output steering wheel state information;
• a compensation logic device configured to determine an elasticity compensation value depending on the driver steering input information and the vehicle state information from stored setting information, and determine and output a target control value based on the motor control value, the elasticity compensation value and the steering wheel state information;
• and
• a motor control logic device configured to control operation of a steering motor to generate an auxiliary steering torque depending on the target control value outputted from the compensation logic device,
• wherein, when the steering wheel is in the steering state, the compensation logic device is configured to compensate for the motor control value outputted from the basic MDPS logic device, using the elasticity compensation value, and is configured to determine a compensated value as the target control value,
• wherein in the stored setting information of the compensation logic device, the elasticity compensation value is set such that the target control value determined by compensating for the motor control value using the elasticity compensation value reduces the auxiliary steering torque to be outputted from the steering motor, compared to that of the motor control value determined before the compensation is performed,
• wherein, when the steering wheel is in the restoration state, the compensation logic device is configured to compensate for the motor control value outputted from the basic MDPS logic device, using the elasticity compensation value, and then is additionally configured to compensate for the motor control value using a recompensation value and is configured to determine an additionally compensated value as the target control value,
• wherein the recompensation value is determined by a value depending on the driver steering input information and the vehicle state information from the stored setting information, and
• wherein in the stored setting information of the compensation logic device, the recompensation value is set such that the target control value determined by additional compensation using the recompensation value increases the auxiliary steering torque to be outputted from the steering motor, compared to that of the target control value determined before the additional compensation is performed.