A4-dof Parallel Mechanism Kinematics Analysis And Parameter Optimization

Compared with the Stewart platform as a representative of6-DOF parallel mechanism the space less degrees of freedom asymmetric parallel mechanism are simple structure, good performance, control easily, high performance price ratio and many other advantages, which have broad application prospects and potential. But research on configuration of new type of parallel mechanical is limit, which affects analysis about this kind of institution because part of its branches is different from others. With other institutions research relatively mature, Institution scholars with different national began to focus on research of the space less degrees of freedom asymmetric parallel mechanism.2TPS/2TPR parallel mechanism is a kind of space less degrees of freedom asymmetric parallel mechanism and connects a rotational vice by series that becomes5-DOF hybrid mechanism.2TPS/2TPR parallel mechanism has a great application prospect.In this paper, a thorough research is made on the structure optimization design of the size of new type2TPS/2TPR. space less degrees of freedom asymmetric parallel mechanism.Firstly, structer of mechanism is describled in brief and kinematics character of it is analyzed.Freedom of mechanism is calculated.The full-jacobian matrix of mechanism is bluit, which incudes movement matrix and restraint matrix. The singular configuration of this mechanism is analyzed in qualitative.Secondly, the evaluation indexes of parallel mechanism are described in detail, which includes ratio between workplace and the volume of mechanism itself, the global condition index. It attains the relation of ratio between workplace and the volume of mechanism itself with size paraments of mechanism and the relation of the global condition index with size paraments of mechanism based on full-jacobian matrix of mechanism. Then, it analyzes the sensitivity of size of parameters of mechanism. The curve of the relationship between performance indicators and change of parameters is calculated and drat. All these provide a theory basis for design of the structure.Finally, Principle of genetic algorithm and related concepts are introduced in brief. It designs parameter of2TPS/2TPR parallel mechanism based on GA and the relations between performance indicators and size of parameters. The best efficient solution of design variables is attained by programming in MATLAB. The result was tested by example. According to the best efficient solution of design, the substance modle is established.