Automatic Generation of Kinematic Joint Model from 3D Assembly Model for Mechanical Product Design

Abstract

To achieve the seamless integration of 3D assembly design and kinematics and dynamics analysis for the development of mechanical products, an automatic generation method of kinematic joint model from 3D assembly model is proposed, which can extract the same mechanism information from different assembly constraint models of the same mechanical product. Firstly, an assembly constraint graph was constructed to represent the 3D assembly constraint model, and an equivalent constraint substitution method was employed to simplify the assembly constraint graph for extracting its intrinsic kinematic closed-chains. Secondly, the screw theory was introduced to recognize the kinematic joint induced by a combination of assembly constraints between two adjacent parts, so that the assembly constraint graph could be converted to kinematic joint graph. subsequently, several identification rules of sub-assemblies which consist of several adjacent parts was established, and the sub-assemblies in the geometric constraint model were identified by using the analysis of degree of freedom, geometric contact analysis and graph search algorithm. In such a way, an assembly constraint model could be converted to a kinematic joint model automatically. Finally, two typical examples have been given to validate the correctness and effectiveness of the proposed method.