Doorway transit navigational referencing system

Abstract

A system of navigational referencing for a robot moving within a defined space is provided. A database contains x-y coordinate positional information on a plurality of doorway openings in terms of an x-y coordinate system. A mobile robot is provided that has the capability to access the database, define its location in terms of an approximate position within the defined space, and sense the presence of one of the plurality of doorway openings. The robot is positioned and moved along a path that traverses the one doorway opening at a known speed. The doorway opening's top door frame is detected from first and second sensor positions on the robot. The first and second sensor positions are separated by a known distance along a line orthogonal to the path that traverses the one doorway opening. An angular orientation of the robot is based on a time difference between when the first and second sensor positions detect the top door frame, the known speed of the robot and the known separation distance between the first and second sensor positions. A y-coordinate position of the robot is based on the positional information from the database when the first or second sensing position detects the top door frame. A lateral position of the robot is determined during a portion of the time between when the first and second sensor positions detect the top door frame. The lateral position is compared with the positional information from the database in order to determine an x-coordinate of the robot.