Basic Loop Method On Type Synthesis Of Kinematic Chain And Configuration Design Of Hybrid Driven Mechanism

Mechanism creative design to a large extent determines the innovation of mechanical products. The main problem of mechanism creative design is the study of the topological structure of the kinematic chain. Kinematic chain type synthesis play a very important role in the mechanism creative design. It has always been a hot topic in the research of mechanism creative design to seek a kind of method for computer to realize the configuration design. At the present stage, there is no complete automation of the mechanism creative design.This paper takes the automatic design of type synthesis of kinematic chain as the research object. Based on creative method of the type synthesis, firstly, the feasible kinematic chains which satisfy the design requirements are selected from the kinematic chain atlas.Then, a reasonable transformation on the frame is carried out according to the need and the approprite links are selected as the driving links. Finally, the mechanisms that satisfy the design requirements are obtained. The main contents of this paper are summarized as follows:Based on graph theory, the basic loop theory is presented which establishes the relationship among the links, the kinematic pairs and the basic independent loops. The basic loop matrix of the kinematic chain and its representation method are presented. The operation rules and operation basic properties among the basic loop matrices are established. The basic loop of the kinematic chain founds the analysis and calculation basis for identifying isomorphism of kinematic chains, identifying and eliminating the rigid subchain, selecting the driving links and the frame transform.The basic loop type sets of kinematic chains are established based on the basic loop theory of kinematic chain. The complex kinematic chain will be resolved into the relatively independent and simple basic subgraph. The isomorphism identification of simple subgraphcan be used as the isomorphism identification of kinematic chains.Through the analysis of the relationship among the basic loops, the method of determining the rigid subchain is presented. The basic loop kinematic chain matrix operations achieve the identification and elimination of the rigid subchain. The calculating process that isomorphism identification and the identification and elimination of rigid subchain are programmed to achieve a computer automation.By analyzing the motion rules of the kinematic chain,the selecting method of driving links of multi-DOF kinematic chain is put forward. The correctness of this method is verified using mathematical method. Based on the basic loop matrix of kinematic chain, the numerical analysis and calculation of driving links selection process of multi-DOF kinematic chain. The automatic selection of driving links of kinematic chain is realized by programming.When the kinematic chain is evolving into a mechanism, seleting different links as the frame may make the mechanism produce the same configuration, i.e. isomorphism problem.The method of mechanism isomorphism identification is put forwrd. With the method of selecting the driving links, the judgment method of the mechanism which satisfies the condition is determined when the driving links are links connected to the frame. Base on the basic loop method of kinematic chain, the calculation process of the mechanism which satisfies the conditions is determined when the driving links serves as the links connected to the frame. The program is programmed to realize the automatic judgment of the kinematic chain with different frame and driving links as the links connected to the frame. It lays the foundation for realizing the automation of mechanism type synthesis.At last, some of 2-DOF and 3-DOF kinematic chains within ten links are analyzed. The mechanisms are determined that the driving links serve as the links connected to the frame.The configurations which can be used as a multi-DOF hybrid driven mechanism are obtained. It lays the foundation of the study of hybrid driven mechanism.