Force And Stiffness Performance Analysis Of Over-constrained 5-DOF Hybrid Manipulators

Combining the advantages of serial / parallel manipulators in terms of work space,stiffness and work accuracy,the 5-degree-of-freedom(DOF)hybrid manipulators has obvious advantages in the processing of complex structural parts in the fields of power equipment,automobiles,rail transit,shipping,aerospace and other fields.However,as the basis of 5-DOF hybrid manipulators design,the two rotational and one translational(2R1T)DOF parallel mechanisms(PMs)still have the problems of the large number of passive kinematic pairs and the unreasonable distribution of limb constraints,and that limit the high-stiffness structural design.In this paper,the force and stiffness performance of 5-DOF hybrid manipulators will be carried out,and the main contents are as follows:Force analysis of the parallel parts 2RPU / UPR,2RPU / UPR / RPR,2UPR / SPR and 2UPU / SP of four typical over-constrained hybrid manipulators is carried out,based on generalized inverse of weighted Moore-Penrose,and the distribution map of force performance of the four parallel mechanism in the scope of work space will be got,and this will lay the foundation for the subsequent research of stiffness performance.To verify the correctness of the analysis of the force performance of the over-constrained 2R1 T parallel mechanisms,establish a mixed model of rigid body and flexible body for simulation based on ADAMS and ANSYS,and compare the simulation results with the theoretical analysis results.Based on the analysis of the force performance of the over-constrained parallel mechanism,the 5-DOF manipulator flexural and torsional stiffness performance is proposed,the factors affecting the robot stiffness performance are analyzed,the weights of various influencing factors on the robot stiffness are analyzed,and the indexes of bending and wrench of the parallel mechanisms is established.By calculating the indexes of the 2RPU / UPR,2RPU / UPR / RPR,2UPR / SPR and 2UPU / SP parallel mechanisms,parallel mechanisms with great stiffness performance will be selected and become the parallel part of the high stiffness 5-DOF hybrid manipulator.The motion characteristics of the selected parallel mechanism on the indexes are analyzed,a 5-DOF hybrid manipulator is constructed,and the virtual prototype structure is optimized for the manipulator.