Abstract: The variation of rigid parts pose errors and assembly forces during the compliant assembly process are analysed. The abnormal situation of peg-in hole assembly explained and the feasible region to perform assembly discussed. The practical ways to improve the assembly effects are suggested. The mathematic models and constraints given not only are the theoretical basis of force-motion planning in robotic assembly task, but also serve as the foundation of the research on all kinds of external compliance technology.

Key words: Assembly automation, Compliance assembly, Robot