Abstract: The stop position of a workpiece is detected by a position detection unit. A control unit calculates and records a difference between the detected stop position (actual stop position) and a reference stop position set in advance. After recording the difference multiple times, the control unit performs a statistical processing of the differences and calculates a compensation amount based on results of the statistical processing. In the next position detecting, the position detection unit is disposed at a compensated position which is obtained by adding the compensation amount to the reference stop position, and in this state, detects the position of a predetermined portion of the workpiece.

Abstract: An objective is to provide a holding device capable of holding a hexagonal part at a nearly fixed orientation. A holding device 1 holds a bolt B by a left claw member 32L and a right claw member 32R. A left recessed portion 34L and a right recessed portion 34R in a recessed manner toward the bolt B in plan view are respectively formed in inner side end portions 33L and 33R facing the bolt B, of the claw members 32L and 32R, a pair of protruding portions 36L and 37L and a pair of protruding portions 36R and 37R protruding toward the bolt B are respectively formed in the portions 34L and 34R, the distances ra and rb from a center O to the portions 36L and 37L are equal in each of the claw members 32L and 32R, and the protrusion interval ? is from d/?3 to d.

Abstract: The stop position of a workpiece is detected by a position detection unit. A control unit calculates and records a difference between the detected stop position (actual stop position) and a reference stop position set in advance. After recording the difference multiple times, the control unit performs a statistical processing of the differences and calculates a compensation amount based on results of the statistical processing. In the next position detecting, the position detection unit is disposed at a compensated position which is obtained by adding the compensation amount to the reference stop position, and in this state, detects the position of a predetermined portion of the workpiece.