Two-handed assembly with immersive task planning in virtual reality

Assembly modelling is the process of capturing entities and activity information related to assembling and assembly. Currently, most CAD systems have been developed to ease the design of individual components, but are limited in their support for assembly designs and planning capability, which are crucial for reducing the cost and processing time in complex design, constraint analysis and assembly task planning. This paper presents a framework of a two-handed virtual assembly (VA) planner for assembly tasks, which coordinates two hands jointly for feature-based manipulation, assembly analysis and constraint-based task planning. Feature-based manipulation highlights the important assembling features (e.g. dynamic reference frames, moving arrow, mating features) to guide users for the ease of assembly and in an efficient and fluid manner. The users can freely navigate and move the mating pair along the collision-free path. The free motion of two-handed input in assembly is further restricted to the allowable motion guided by the constraints recognised on-line. The allowable motion in assembly is planned by the logic steps derived from the analysis of constraints and their translation in the progress of assembly. No preprocessing or predefined assembly sequence is necessary since the planning is produced in real-time upon the two-handed interactions. Mating features and constraints in databases are automatically updated after each assembly to simplify the planning process. The two-handed task planner has been developed and experimented for several assembly examples including a drill (12-parts) and a robot (17-parts). The system can be generally applied for the interactive task planning of assembly-type applications.