Motion and Constraint Analysis Based on Screw Theory

The paper introduces a complete constraint analysis method based on screw theory. In the first place, Each KC of product is analysed and decomposed into feature-class KC. Assemblies are then decomposed to parts and joint features. The motion and constraint status is described by screw matrix (twist matrix and wrench matrix). Part-feature diagram(PFD)and constraint-transfer diagram (CTD) are introduced to identify the path for constraint analysis of each feature. After identifying the path, how to make constraint analysis for serial and parallel constraint using MATLAB algorithm is described. Finally, a "DOF&constraint analysis" system is developed via C++ programing and embedded in Pro/ENGINEER environment. Using this analysis system in Pro/ENGINEER significantly reduces design cycle and achieves both efficiency and accuracy.