US Patent 8965691 Position and direction determination using multiple single-channel encoders

A system for an autonomous vehicle is disclosed that combines information from single-channel encoders serving as wheel speed sensors on multiple wheels of the vehicle. A pattern of the outputs from the single-channel encoders is characterized while the vehicle is traveling in a first direction. A shift in the characterized pattern is associated with a change in direction of the autonomous vehicle. Such detection of changes in direction can be used to determine the position of the vehicle at low speeds or while starting and/or stopping where the vehicle can potentially rock back and forth.