Angular Velocity Sensor
An EPS equipped vehicle has an Angular Velocity Sensor (AVS) in the multifunction switch. AVS is composed of a set of photo interrupters (light emitting diode, photo TR and slitted disc).
The slitted disc has 18 outer slits for detecting steering wheel rotating direction and angular speed. And an inner slit is provided for checking whether wheel position is within neutral or not. Two sets of LED and photo transisitors check rotation of steering wheel, calculating the degrees per time through on, off photo transistor, and a set of LED and photo transistor is used to sense wheel location. With the signal from sensors, the EPS control module miscellaneously decides current flow to the solenoid valve from 0 amp to 1 amp, compensating steering wheel effort. See Fig 1 .