Mechanism Research On A 3/3-RRRS Parallel Manipulator

As the basic elements of mechnism research, the Mechanism and Kinematic Analysis has played a foundational role in the Research and Develop of a mechanism, also has provided an important and indispensable theoretical basis to the application and promotion of the mechanism. This thesis mainly conducted the thorough and systematic theoretical researches on a novel 3/3-RRRS(Revolute-Revolute-Revolute-Spherical) parallel manipulator with six DOF(degree of freedom). After a brief introduction of the 3/3-RRRS parallel manipulator, the mechanism is detailedly analysed, based on which the kinematics, workspace and singularity analyses are deeply studied. After that, the kinematics and dynamics simulations are presented and the simulation results are considered as an important part of the thesis.DOF calculation formula about complex space mechanism is applied to analyse the DOF of the 3/3-RRRS parallel manipulator, meanwhile, Pro/E model and ADAMS model are built to double check the result. A three-dimensional model and its relevant structure diagram of the parallel mechanism are constituted, and constraint equations based on the geometry are established to carry on the forward and inverse displacement analyses of the 3/3-RRRS parallel manipulator, especially, a novel geometrical method referred as equivalent mechanism is proposed for the forward displacement analysis of the manipulator under consideration. After solusion, the method is comprehensively compared with the traditional forward displacement method. Software MATLAB is used to solve the inverse displacement equations for a symbolic solution. Two groups of numerical examples are taken to demostrate the theoretical analysis.Based on the displacement analyses of the manipulator, a discretization method is proposed for the computation of the reachable position/orientation workspace of the 3/3-RRRS parallel manipulator, respectively. Four examples of a 3/3-RRRS parallel manipulator are given to demonstrate these theoretical results, change rules are discussed in detail. Similarly, the method of searching algorithm in 3D space is applied to the singularity analysis, coordinate of all possible stable positions are substituting into the Jacobian, position-singular points under given orientation condition are conformed.On the basis of the kinematic model and structural parameters, mechanical model of the 3/3-RRRS parallel manipulator are created in ADAMS, kinematics and dynamics simulations are carried out practically, and the kinematic and dynamics performance are evaluated according to the simulation results.