Synthesis Of Elimination Inside Singularity Branched Link With Actuation Redundancy For Parallel Mechanisms

With the development of science and technology, the application field of parallelmechanism is becoming wider and wider. Such as in the field of aerospace, machinerymanufacturing, computer aided manufacturing and so on. But because of the singularity,the application of parallel mechanism is affected. In order to eliminate the singularity ofparallel mechanism, the redundant actuation branched chain comprehensive theory andoptimization about eliminating internal singularity of the parallel mechanism aresystematically studied in this paper. The major studies are as follows:Based on eliminating the internal singularity of the parallel mechanism withredundant actuation, a synthesis method about redundant drive branched chain is proposed.Without changing the rank of structure constraint spiral, to make the rank of theconstraints screw is certain when the singular configuration happened by adding someconstraint force or couple on the basis of the original constraints screw. The internalsingular can be eliminated by this method.In order to eliminate the internal singularity of the parallel mechanism, thedistribution of singularity need to be listed according to the mixture screw systemdiscrimination theory and the geometric method. Then the screw needed can bedetermined. And based on the duality of screw, the redundant drive branched chains forparallel mechanism which can meet the requirements can be systematically synthesized.Including the branched chain types, number and the spatial distribution of the redundantdrive branched chains which conform to the requirements.For a typical parallel mechanism4-UPU, the possibility of the singular form isanalyzed and research, and the redundant drive branched chains for this parallelmechanism which can eliminate the internal singular are systematically synthesized in theway mentioned. The dexterity and carrying capacity of the whole performance indicatorsof the parallel mechanism with different redundant redundancy branched chains arestudied, using MATLAB software, the corresponding full performance maps are plotted,the relationship between performance and size of the parallel mechanism is analyzedthrough the graph, the optimization problem of different redundant drive branched chain is discussed under the same mechanism size.Using finite element simulation software ANSYS, the stiffness performance of theparallel mechanism with different redundant redundancy branched chains is simulated.The change law of stiffness between parallel mechanisms with different redundantredundancy branched chains is found, and the correctness of the theoretical analysis isverified.