An autonomous floor cleaning robot includes a robot body, a drive supporting the robot body to maneuver the robot across a floor surface, a pad holder attached to an underside of the robot body and configured to receive a removable cleaning pad, and a pad sensor configured to sense a pad type identifier on a central region of the cleaning pad. The pad type identifier includes a marker on the central region of the cleaning pad. The cleaning pad has a mounting card affixed thereto, and the pad type identifier includes an array of apertures that expose selected portions of the marker.