Abstract: Aiming at the human-computer interaction, behavior simulation and user design in virtual assembly, based on the complex gearbox of large tractors, the simulation method of dynamic motion and behavior of gear with multi-collision body is studied. The positioning method of multi-part model based on axis constraints and surface constraints in virtual environment is proposed. The virtual environment of human-computer interaction is developed. The consumed time of per frame is about 10 ms, and the complex variable-speed motion behavior and its simulation are realized. The virtual assembly system is equipped with AR interface, which can realize the active intelligent virtual assembly by hand. The experiments show that the system can provide active virtual assembly, interference detection, assembly knowledge learning, program design, and assembly error messages of the user requirements. It provides a simulation scalable platform for virtual manufacturing and assembly of complex gearboxes.

Key words: virtual reality, gearbox, motion simulation, virtual assembly, collision detection