Patent ID: 8306660

Claim:
A device for restoring positional information of a robot provided with a first member and a second member connected in a manner movable relative to each other via an articulation axis; a motor moving the second member relative to the first member; and a sensor outputting a sensor signal according to a driving amount outputting a sensor signal according to a driving amount of the motor, the device being capable of validating positional information depending on the sensor signal based on a reference position of the articulation axis, the positional information is invalidated for a reason that a component affecting a correlation between the sensor signal and a relative movement of the second member relative to the first member is removed or replaced after the correlation is determined with respect to the reference position, wherein the first member and the second member are provided with a first mark and a second mark, respectively, the first mark and the second mark representing a positional relationship between the first member and the second member; and wherein the device comprises: an imaging section obtaining an image signal in a region including the first mark and the second mark; a mark position computation section computing a first positional relationship between the first mark and the second mark at a first time before the component is removed or replaced, based on an image signal obtained by the imaging section at the first time, and computing a second positional relationship between the first mark and the second mark at a second time after the component is removed or replaced, based on an image signal obtained by the imaging section at the second time; a motor control section controlling the motor at the first time so that the first positional relationship computed by the mark position computation section becomes a predetermined positional relationship, and controlling the motor at the second time so that the second positional relationship computed by the mark position computation section becomes the predetermined positional relationship; and a correction section correcting positional information depending on a sensor signal output by the sensor after the second time, based on a first sensor signal output by the sensor after the motor is controlled by the motor control section at the first time and a second sensor signal output by the sensor after the motor is controlled by the motor control section at the second time.