Type Synthesis Theory And Instantaneous Mobility Analysis Of Parallel Mechanism Based On The Screw Theory

Several approaches for type synthesis of parallel mechanism are:screw theory,Lie groups and Lie algebras,SOC(single-opened-chain)theory and so on.From observing above one hundred novel mechanisms are obtained in this paper based on the screw theory and combination method which includes 2-DOF(degrees of freedom)parallel mechanisms and 4-DOF(degrees of freedom)parallel mechanisms with three translation freedoms and one rotation freedom.The kinematic analysis and virtual prototype simulation analysis of a typical mechanism are performed in this paper.In this paper screw theory study on the compass kinematic characteristics found a new class of parallel mechanisms,which a typical mechanism called the Compasses mechanism.Compasses mechanism for the two chain parallel mechanism with closed-loop chains,with one-dimensional rotating three-dimensional translation space four degrees of freedom movement,the mechanism structure is simple,easy control,and can achieve 360 degrees the whole week rotation compared with the famous Quattro robot.In all,the contents includes:(1)Combine the type synthesis approach with the mechanism real motion derivation methods this paper gives the movement output of moving platform based on the observation of compasses motion law.An array of novel mechanisms are obtained based on the motion branch chains synthesized by the type synthesis approach.(2)Mathematical model of compasses mechanism is set up and then the position relation function and the forward and reverse kinematic model of compasses mechanism are obtained by the splitting method.Based on the above model,velocity and acceleration model as well as the first order and the second order kinematic influence coefficient are gained.(3)The singularity configuration and workspace of the compasses mechanism are analysed by the geometric method and the splitting method.Boundary conditions of actuators,the first and the second five-bar mechanism are obtained,so the theoretical workspace of this mechanism is acquired with softwares.(4)Parts and components are built through the software of PEOE,which are transported to the software of ADAMS to found the quality parameters and the restraint relations.The feasibility of compasses mechanism in the area of industrial robot is verified by the forward and reverse simulation.