An autonomous floor cleaning robot includes a body, a controller supported by the body, a drive supporting the body to maneuver the robot across a floor surface in response to commands from the controller, and a pad holder attached to an underside of the body to hold a removable cleaning pad during operation of the robot. The pad includes a mounting plate and a mounting surface. The mounting plate is attached to the mounting surface. The robot includes a pad sensor to sense a feature on the pad and to generate a signal based on the feature, which is defined in part by a cutout on the card backing. The mounting plate enables the pad sensor to detect the feature. The controller is responsive to the signal to perform operations including selecting a cleaning mode based on the signal, and controlling the robot according to a selected cleaning mode.