Assembly planning effectiveness using virtual reality

Planning the sequence of components (or parts) to be assembled during manuf acturing is an important application problem for virtual environments for t hree main reasons. First, it is a difficult combinatorial optimization but a highly visual problem. Second, a majority of assembly operations in facto ries (with the exception of simple pick-and-place operations) are still per formed manually, because they are difficult to automate. Hence, it is an im portant problem involving human-machine interface. Third, there are a numbe r of assembly operations which require dextrous operator training. Hence, i t is also an important training problem. Recent research suggests a promisi ng approach for assembly determination based on using heuristic rules to ge nerate soft constraints in addition to the regular hard quantitative constr aints due to part geometry and topology. We believe that the emergence of v irtual environments can enable us to systematically use these soft constrai nts, which previously has not been possible. In this paper, we report resul ts of experiments involving fifteen voluntary participants using a nonvirtu al reality (VR) environment involving blueprints, a nonimmersive desktop VR environment, and an immersive projection-based VR environment to first tea ch participants skills in handling soft and hard constraints for assembly p lanning through examples, and then to measure the effectiveness of their le arnt skills in solving a different example problem. We have classified soft constraints as infeasibility constraints, reorientation constraints, diffi culty constraints, instability constraints, and dissimilarity constraints. A significant observation is that the participants could, on average, perfo rm the assembly operations in approximately half the time in the immersive and nonimmersive VR environments than in the traditional environment using blueprints.