A Method Of Selecting Optimization Of Parallel Mechanism Based On Fuzzy Mathematics

The lower-mobility parallel mechanism (stands for parallel mechanism with2,3,4,5degrees of freedom) has advantages of simple structure, low weight, simple control and lowcost in manufacturing and so on. So lower-mobility parallel mechanism has become aresearch focus in parallel mechanism fields. However, until so far, very few lower-mobilityparallel mechanism have been used in practice because of the two following reasons: first,it is hard to establish type synthesis system of lower-mobility parallel mechanism; second,there are no sophisticated choosing optimum evaluation theory of lower-mobility parallelmechanism.So it has significant theoretical and practical value to do the work on typesynthesis and choosing optimum evaluation. Taking the2R1T lower-mobility parallelmechanism,in this paper, the author makes a systematic research on topological structuresynthesis theory and a method of selecting optimization of parallel mechanism. The mainwork of this paper are as follows:According to the topological structure synthesis method based on POC sets,150typesof2R1T parallel mechanism has been synthesized, the procedures of the above methodare:first, figuring out the POC set of every branch of the parallel mechanism. Secondly，figuring out the structure type of these branches. Thirdly, figuring out the number,combination solution and direction configuration of these branches. At last, the2Dstructure of the mechanism are provided.The method of selecting optimization of parallel mechanism based on fuzzymathematics has been established in this paper. In this method, a comprehensive fuzzyevaluation (CFE) model is confirmed based on the performance evaluation index ofparallel mechanism. Using AHP, this method gives the weights of evaluating factors.According to those weights, we get the fuzzy set of importance of the evaluation factors.Choosing the generalized fuzzy synthetic operation, we get the Fuzzy comprehensiveevaluation set. This method is simple, practical, and of high efficient. It Provide atheoretical reference for the choosing optimum evaluation of the lower-mobilityparallel mechanism.