Kinematic Analysis And Optimization Design Of A 2-PRU-2-UPR Redundantly Actuated Parallel Manipulator

As an important branch of lower degree of freedom(DOF)parallel manipulator(PM),3-DOFs with two rotational DOFs and one translational DOF(2R1T)parallel manipulator has been a research hotspot in recent years.In this paper,a novel 2-PRU-2-UPR redundantly actuated PM is proposed.The kinematics and performance analysis of this PM is researched.Based on the optimization,a prototype has been designed and assembled.The main contents are as follows:A novel 2-PRU-2-UPR redundantly actuated PM is proposed.Coordinate systems of this PM are established.The DOF of this PM is analyzed by using screw theory.The results show that this PM has two rotational DOFs and one translational DOF.Kinematic position analysis of this PM is carried out.Inverse kinematic solution of this PM is derived from geometric relations.The forward kinematic analysis is given by numerical method.The conclusion shows that this PM has the unique forward or inverse kinematic solution in the effective workspace.The workspace about this PM is plotted by numerical search method.A simulation example is given to verify the correctness of the kinematic analysis and workspace analysis of the proposed PM.The Jacobian matrix is derived from the total differential of the inverse position solution of this PM.And the velocity mapping relationship is given based on the Jacobian matrix.Furthermore,the singularities of this PM are discussed.There are two kinds of inverse kinematic singularities,without forward kinematic singularity or combined singularity.The addition UPR limb effectively avoids the forward singularity compared with non-redundant ones.The performance of the 2-PRU-2-UPR redundantly actuated PM is analysised by using the local transmission performance and virtual work stiffness index.The optimization objective is defined by the local transmission performance,and the relationship between transmission performance and parameters was obtained,which supports the prototype design.Finally,the prototype design of 2-PRU-2-UPR redundantly actuated PM is completed,including the general layout of the PM,the selection of outsourced parts and the design of structure bar.The results in this paper support for the follow-up study of the 2-PRU-2-UPR redundantly actuated PM and contribute to the application of redundantly actuated PMs in parallel machine tools.