Abstract:

Based on the traditional definition of decoupling parallel mechanism, and combined with the research status of three DOFs rotational decoupled parallel mechanism, a new concept of generalized decoupling is proposed. In the definition of generalized decoupling, the output parameters of parallel mechanism are demanded to meet the requirements that the different movements of same output parameter can be directly superposed, so as to obtain better output characteristics for translational or rotational decoupled parallel mechanism. According to the relationship between the movements of parallel mechanism and its branches, a new method of type synthesis is proposed for decoupled parallel mechanism, including the programming and distribution of branches’ movements, configuration design and combination of branches. On the basis of characteristics of kinematic pairs in parallel mechanism, the conditions for branch to achieve single rotational DOF around one axis are analyzed and obtained. According to the rotation conditions of parallel mechanism, a new concept of rotation unit is proposed. Based on the definition of generalized decoupling parallel mechanism, a set of parameters that meet the requirements are selected to be the output parameters of the three DOFs rotational parallel mechanism. By applying the new method of type synthesis and coupled with the concept of rotation unit, tons of three DOFs rotational generalized decoupling parallel mechanisms are worked out. Thus, the concept of generalized decoupling and the new method of type synthesis are proved to be feasible and effective. The research provides a theoretic foundation and new design approach for type synthesis of decoupled parallel mechanism.

Key words: movement of branch, output parameter, rotation unit, type synthesis, generalized decoupling