A novel force rendering approach for virtual assembly of mechanical parts

Abstract

Virtual assembly (VA) is a typical virtual reality (VR)-based application in engineering. However, common interaction devices, such as keyboard and mouse, are less realistic due to lack of force sensation. Therefore, realistic force feedback in the VA environment provides a more natural interaction to simulate the assembly operation and result in improved task efficiency. This paper presents a novel force rendering approach, which focuses on mechanical part assembly based on three basic mechanical fit types, namely clearance fit, interference fit, and transition fit. The algorithm to calculate the assembly force is formulated by analyzing the tolerance variation along the assembly length between two mating parts. And then the force is rendered continuously at real-time during the VA operation to provide a fast, stable, and more realistic assembly force feedback to the users. Several comparative case studies are conducted to investigate the approach with the users’ performance of VA with the other three common approaches, namely conducting assembly task using a WIMP-based CAD software, with a standard physically based approach and the one with both collision detection and geometric constraints, respectively. The proposed approach is more efficient than other approaches by providing continuous force feedback to the users so as to greatly enhance their force sensation of the assembly operation. Moreover, case studies on users’ identification capability of different fit types has shown that with the continuous force rendering, users can easily tell the clearance fit from the other two fit types, hence the proposed approach equips users with the ability to possibly evaluate the assembly performance at the early stage of product development process.