Apparatus and method for calculating absolute angular position for controlling vehicle steering system

A vehicle steering system, comprising:

• a motor assembly comprising a motor having a first rotor and a motor position sensor configured to sense a first rotor angle of the motor in a single-turn range;
• a rotary-to-linear conversion mechanism operably coupled between the motor assembly and a steering rack to convert a rotational force of the motor into a linear force for moving the steering rack, the rotary-to-linear conversion mechanism comprising a second rotor operably coupled to the first rotor of the motor and an angular position sensor configured to sense a second rotor angle of the second rotor of the rotary-to-linear conversion mechanism in a single-turn range, wherein the steering rack is operably coupled to a pinion;
• and
• a processor configured to calculate an absolute angular position associated with a position of the steering rack in a full-turn range associated with movement of the steering rack based on the sensed first rotor angle of the motor and the sensed second rotor angle of the second rotor of the rotary-to-linear conversion mechanism using ratio between rates at which the first rotor of the motor and the second rotor of the rotary-to-linear conversion mechanism rotate.