Electric power Assisted Steering(ePAS) system has following components:-
1. Electric Motor
2. Reduction Gear
3. Torque Sensor
4. Vehicle Speed Sensor
6. Steering Angle Sensor
In the picture clear all the position of components.
Electric Control Unit(ECU) calculate the assisted torque on the bases of wheel position, vehicle speed and torque applied by driver on steering wheel.
then ECU give signal to electric motors which rotates the steering gear which reduce the torque required by driver.
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Electric Power Assisted Steering Works click here