Pitch changing mechanism, clamping device and manipulator

The utility model relates to a pitch changing mechanism, a clamping device and a mechanical arm. The at least two pitch changing pieces are movably arranged on the rack in the preset direction; the driving assembly is in driving connection with at least one variable-pitch part and drives the variable-pitch part to move in the preset direction; the connecting rod mechanism comprises at least two sub connecting rods which are in one-to-one correspondence with the variable-pitch pieces, and all the sub connecting rods are sequentially connected between the variable-pitch pieces so as to adjust the distance between the variable-pitch pieces when the variable-pitch pieces move; and the detection part is used for detecting the position of the variable-pitch part on the rack so as to improve the moving precision of the variable-pitch part. When the driving assembly drives the variable-pitch pieces to move in the preset direction, the sub-connecting rods connected between the variable-pitch pieces can limit the dista