No abstract

This paper surveys studies of mechanical assembly for developing complicate products from various prospects, i.e., feature, constraint, mating, modeling, motion, and relationships. Firstly, a brief introduction is given on how to model features. Secondly, the types of relationships among assembly configurations are presented. Thirdly, choices of various model-structures for assembly information are surveyed. Finally, directions for further studies are suggested.

For finite rigid body motion, every two successive screw displacements can be represented by one equivalent screw displacement. However, such phenomenon should not be considered naturally to be valid for incompletely specified displacements (ISDs). There is neither a precise statement for such phenomenon nor an understanding of its range of validity within ISD, such as line segment displacements. As one of the main contributions in this paper, based on dual vector algebra and screw theory, an algorithm is provided to prove the existence of the subset within the scope of the line segment motion, which expresses the similar relation as shown in finite rigid body motion. A numerical example is presented for illustrative purpose.

In this paper, a novel geometric model for a planar slider-crank mechanism is established to quantify the position uncertainty of a coupler point caused by joint clearances. The clearance of each revolute and prismatic joint is characterized by a short clearance link. The prismatic joint with clearance is modeled as a link with infinite link length and a variable short link. The linkage with joint clearance is thus modeled as one with redundant freedom. The uncertainty is the result of the redundancy and the extremity of the redundancy is determined through Ting’ N-bar rotatability laws.