The overall goal of this research is to improve the design of assembly methods through the use of virtual reality (VR) and haptics (force feedback). The research is focused on two critical aspects: the development of methods for simulating natural part-to-part interaction to support the human-centric approach to concurrent design and the evaluation of these methods in a manufacturing design context. As part of the research, we have developed the SPARTA software platform, explored new VR interaction methods and conducted several site visits at Deere facilities to better understand their processes and operations. This paper summarizes the efforts and results to date.