Research on Bidirectional Macro-Micro Assembly Technology Accuracy Based on 3-UPU Parallel Mechanism

摘要

The accuracy question for macro-micro assembly technology is essential for the design of bidirectional macro-micro assembly. The paper presents some new ideas that are different from the traditional design. A complex motion is decomposed into two simple motions. One (named assembling part) of the two assembled objects is fixed on the moving 3-UPU parallel mechanism (3 represents three degrees of freedom, U represents the hook pair, P represents the moving pair), and the other (named assembled part) is fixed on the rotating 3-UPU PM (parallel mechanism). By macro-micro motion of the PM, both assembling part and assembled part are assembled in three-dimensional space. By the design, both the mechanism and its motion control are simplified. Further more, both the kinematics analysis and accuracy simulation analysis of the 3-UPU PM are discussed. In order to improve the assembly accuracy, the kinematics analysis and simulation accuracy analysis for PM is an essential part of the design. And with the decrease of structure parameters error, the moving platform center accuracy will gradually be improved. Compared with the structure parameters error for PM, the centre moving error of the moving platform is smaller. In a certain extent, there is coupling error rather than the accumulation error for PM. By the analysis of hook pair error, the factors that affect the accuracy of the PM are found. And it provides theoretical design basis for the application of the PM in the macro-micro assembly technology.