A grasping unit provided with a hand unit is used when conveying magnetic tape cartridges and optical cartridges (hereinafter, referred to as cartridges) in a magnetic tape library device. The grasping unit moves up, down, right and left, and transfers cartridges between an intended storage unit and a cartridge drive device.
The grasping unit determines a storage unit storing a cartridge to be conveyed, moves to the front of the storage unit, makes the hand unit grasp the cartridge, and carries out the transfer of the cartridge.
At this time, it is desired that the hand unit is positioned properly to the target cartridge. Conventionally, various approaches of positioning such a hand unit have been proposed. For example, a correction method of a position data and an object position determination system have been known as related arts to determine or correct the position of the conveying robot (see. Japanese Laid-Open Patent Publication Nos. 5-342723 and 2000-314611).