Patent ID: 6895357

Claim:
A method for determining an actual steering wheel angle θ of a vehicle steering mechanism, the vehicle steering mechanism having an initial steering wheel angle θ 1 when the vehicle enters an ignition-on state, the vehicle steering mechanism having a center steering wheel angle θ 0 when the vehicle is heading straight-forward, the method comprising the steps of: determining a semi-relative steering wheel angle offset Δθ representing the difference between θ 1 and θ 0 ; storing Δθ in erasable programmable read-only memory when said vehicle enters an ignition-off state; measuring a relative steering wheel angle θ R from a semi-relative steering wheel angle sensor during the ignition-off state; retrieving Δθ from the erasable programmable read-only memory when said vehicle enters an ignition-on state; continuing to measure the relative steering wheel angle θ R from the semi-relative steering wheel angle sensor during the ignition-on state; and determining said steering wheel angle θ based on θ R and Δθ.