Steering angle determaination method and apparatus

In a vehicle with a hand wheel, steerable wheels positionally responsive to the hand wheel and a steering position sensor coupled to the handwheel and providing a handwheel angle signal indicative of an angular position of the handwheel, a steering angle determination apparatus comprising:

• a first filter having a first input and a first output, wherein the first input receives the handwheel angle signal from the steering position sensor and the first output provides a first filtered signal;
• a window comparator having a center input, a data input and a comparison output, wherein the first filtered signal is coupled to the center input and the handwheel angle signal is coupled to the data input, wherein the window comparator defines a window around the first filtered signal at the center input and provides a positive comparison signal at the comparison output when the handwheel angle signal at the data input is within the window;
• a second filter having a second input and a second output, wherein the second input receives the handwheel angle signal and the second output provides a second filtered signal that (a) is updated in response to the handwheel angle signal when the comparison output provides the positive comparison signal and (b) remains substantially fixed when the comparison output does not provide the positive comparison signal, wherein the second filtered signal represents an offset between the handwheel angle signal and a steered position of the steerable wheels.