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 diode (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 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 analysis performance of the system is improved by providing the fixed slit in front of the LED, and thereby identifying the brightness and darkness of the light which is received at the photo transistor. 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. See Fig 1 .