Steering Angle Sensor
The steering angle sensor detects the steering wheel turning angle. A disk with evenly spaced slits is positioned between the facing parts of a light emitting part (LED), and a light receiving part (photo transistor). As the disk rotates, it interrupts the light from the LED. The light which passes through a slit is converted into the electric current by the photo transistor, and the waveform of this electric current is converted by the comparator into a square wave output of the disk's rotation.
The output signal is a 2-phase output (A-phase and B-phase), and the steering wheel turning angle and the turning direction are calculated by the VSA control unit.