Human-centric Collaborative Assembly System for Large-Scale Space Deployable Mechanism Driven by Digital Twins and Wearable AR Devices

The mass personalization of spacecraft challenges the experience and skill of assembly operators, which is caused by the poor collaboration between the elements in assembly. A large number of research works show that the role of human is irreplaceable in the process of assembly, but few publications focus on improving the collaboration to reduce the strict requirement for operators. To address those challenges, this paper proposes a human-centric collaborative assembly system (HCAS) for Large-scale Space Deployable Mechanism (LSDM) that is the core supporting structure of satellite, to solve the problem of poor collaboration between human and the resources in assembly site. Three Digital Twins (DTs), i.e., assembly process DT, assembly operator DT, and assembly quality DT are developed to achieve the collaboration among the elements of human-cyber-physical in HCAS. The breakthroughs brought by the three DTs are 1) adaptive assembly process sensing based on real-virtual scenes fusion with the help of assembly process DT and wearable AR device enhances the synergy between physical system and cyber system; 2) Based on the assembly operator DT and the Knowledge Graph, the adaptive assembly tasks assignment with operator-centric is realized; 3) Dynamic tolerance allocation of LSDM assembly considering space service environment based on assembly quality DT guides the operator to adjust the process parameters in real time. In addition, in view of the special requirement of gravity compensation of LSDM assembly, the method of using Co-robot to simulate microgravity and AR to plan robot path online is included to improve the human-machine collaboration. Finally, a prototype system is developed and applied in assembly site. Application results show that the developed method and system reduce the dependence on human experience and debases the frequency of rework, which achieve the purpose of improving assembly efficiency and quality.