Automatic Structure Synthesis Of Fractionated Kinematic Chains Based On Atlas Database

Mechanisms structure synthesis is the important stage of the mechanical design richin creativity and vitality, it can not only improve and optimize the structure of existingorganizations, but also can create new mechanisms. In recent years, with the deepening ofthe study of the structural of mechanisms, mechanisms structure synthesis has achievedfruitful achievement, kinematic chains having various structures are synthesized, whichgreatly promotes the process of the mechanisms selection and the structure optimization ofmechanical design. However, with the advances in technology and machinery industrial,the mechanisms with simple structure can not meet the demand of the market, whichmakes the study of mechanisms structure synthesis turn to more complex. Mechanism offractionated structure is a complex mechanism, is also a very important mechanism, andhas been widely used in machinery products and the High-tech field. But previous to thistype of mechanism kinematic chains’ system comprehensive study is poor, so the structuretype of the planar fractionated kinematic chains’ synthesis has important theoretical andpractical significance.Based on the atlas database of closed-loop kinematic chain synthesizing planarfractionated kinematic chains, fractionated kinematic chain is the combination ofnon-fractionated kinematic chains. This paper introduces the related concepts andterminology of mechanisms synthesis, graphical representation and the matrix expressionof kinematic chain, and the related knowledge of isomorphism kinematic chain. Based onplanar separable basic kinematic chain separation type, deduce the plane separableseparation of kinematic chain type solving equation, to determine the basic kinematicchain of separable closed-loop kinematic chain and their combination type. Based on thecharacteristics of the fundamental fractionation type, we deduce solving equations ofplanar fractionated kinematic chains, to get links and DOFs of basic closed-loop kinematicchains.Then, a method to determine whether two of vertex-groups symmetric is introduced to achieve synthesis of planar fractionated kinematic chains, to determine whether twolink-groups symmetric, by the information of classification of link-groups, joints ofmaximal loops, link position in the maximal loops and maximum adjacency matrixes. Theapproach can avoid isomorphic kinematic chains in the process of synthesis.On the basisofL, J, D-J and L-J synthesis type of basic closed-loop kinematic chain. we derivekinematic chain formula, and realize classified automatic structure synthesis of4-DOFfractionated kinematic chains. The number of9,11and13link4-DOF fractionatedkinematic chain gotten by this method and the number in the literature are same, and forthe first time to get all structures of15link4-DOF fractionated kinematic chains.