Abstract: Disclosed is an automatic carrier system having one or more self-propelled robotic carriers for carrying products-in-assembly between assembly stations of an automated assembly line. The running speed and stopping position of individual carriers is controlled by command indicators. The carriers are capable of stopping within a small distance of a desired position relative to an assembly station. Each carrier supports a pallet upon which is slidably disposed a subpallet. Each assembly station has a robotic arm upon which is located a positioning member and an assembling tool. Accurate positioning of product-in-assembly is effected by lowering the positioning member, which comprises two cylinders with tapered openings, over a pair of positioning projections mounted on the slidable subpallets. As the positioning projections slide within the tapered opening of the positioning member cylinders, the sloped surface of the tapered opening causes the positioning projections to move toward the center of the cylinders.