A method of providing a Social Networking Service based on a phone book of a mobile terminal is provided. The robot includes an articulated arm, moving according to a plurality of numerically controlled axes and supporting a suction head. The exposure control mechanism comprises a diaphragm made up of diaphragm blades movable on a plane perpendicular to an optical axis in opposite directions to define a diaphragm aperture, and an ND filter made up of at least two ND filter elements having different transmittances. A simpler interface for each user can be provided to prevent other users from deleting recorded files, which have not yet been viewed.