Abstract: A vehicle power steering system has a steering shaft with a rotational position sensor providing signal rollover so that each sensor output indicates a plurality of potential absolute steering positions separated from each other by multiples of a rollover angle. Upon each initiation of vehicle operation, the system selects, as an unadjusted steering position, one of the plurality of absolute steering positions corresponding to an initial sensor output; and the system repeatedly updates the unadjusted steering position in response to sensor output changes, including sensed rollover events. The system repeatedly tests a set of revolution offsets with the updated unadjusted steering position and excludes any which indicate an out-of-range absolute steering position. The final remaining revolution offset is latched as the correct value.

Abstract: A vehicle power steering system has a steering shaft with a rotational position sensor providing signal rollover so that each sensor output indicates a plurality of potential absolute steering positions separated from each other by multiples of a rollover angle. Upon each initiation of vehicle operation, the system selects an absolute steering positions corresponding to an initial sensor output as an unadjusted steering position and repeatedly updates the unadjusted steering position in response to sensor output changes, including sensed rollover events. The system stores data dividing a two dimensional map of possible vehicle steering operating points defined by total steering torque and steering position into a first region of likely vehicle steering system operating points, a second region of unlikely steering system operating points indicating a revolution offset in a first direction, and a third region of unlikely steering system operating points indicating a revolution offset in an opposite direction.