Digitization of assembly line for complex products - The digital nursery of workpiece digital twins

During the last decade the use of digital twins has been spreading to various complex systems, such as assembly lines, and complex products such as aircraft, drones, satellites, vehicles and machinery. This paper discusses the considerations related to the interaction between the assembly-line digital twin and the digital twins of the evolving complex products (workpieces). The paper proposes hierarchical framework including the assembly-line digital twin at the top, that employs the workstation digital twins which are temporarily connected to their current workpiece digital twins. The result is a system that can accurately and efficiently synchronize these simultaneous digital twins. A shared data structure is proposed to facilitate the control and tracking of the assembly progress of each workpiece. This data structure is carried with the workpiece and is shared with the current station digital twin and if necessary the line digital twin.