Design And Analysis Of New Kinematically Redundant Parallel Manipulators

Parallel manipulator has many advantages,such as high motion accuracy,strong bearing capacity and simple position inverse solution,etc.However,it also has some disadvantages,such as difficult to eliminate self-motion,low fault tolerance pergormance and difficult to avoid singular configuration.The parallel manipulator with redundant structure can not only retain the advantages of the parallel manipulator,but also make up for some shortcomings of the parallel manipulator,and can achieve the purpose of eliminating self-motion and avoiding singular configuration.Based on the above background,this paper proposes a kind of configuration design scheme of a class of kinematically redundant parallel manipulators(KP-RMs),and optimizes one of the typical configurations,carries out corresponding theoretical analysis and virtual simulation,and finally makes a task-oriented physical prototype to verify its characteristics,which provides certain value for the engineering application research of structural redundant parallel manipulator.(1)This paper focuses on the design theory of configuration synthesis based on relative degree of freedom(RDOF)criterion and the modified Griibler-Kutzbach(G-K)criterion,and selects the basic parameters of the manipulator through the theory,and obtains the number of components in different forms.The components are distributed to the respective motion branches,and the basic motion pair conecting the branches to the base is arranged,and then the motion branchs of the assembly manipulator are completed,and different types of structural redundant parallel manipulator configurations are designed.A three-dimensional modeling of some new redundant parallel manipulators is carried out,and the specific structures of each part are introduced respectively.Based on the design principles of symmetrical structure,easy control and easy processing,a new 3-PRR(P-3RR)S parallel manipulator is selected as the follow-up research object,and named as a new type of redundant parallel manipulator.(2)The position inverse solution of the new structure redundant parallel manipulator is analyzed,the workspace is drawn based on kinematics equation,and then the research on singularity,dexterity and stiffness is carried out,which lays a theoretical foundation for subsequent optimization.(3)The size optimization design of the new structure redundant parallel manipulator is carried out.Based on different performance indexes,the size parameters of each part are optimized by genetic algorithm.A group of optimal solution data is selected as the structural design parameters of the new structure redundant parallel manipulator.Then the degree of freedom simulation and verification are carried out in ADAMS software,and the theoretical calculation is carried out by using MATLAB.The correctness of kinematics analysis is verified by the interaction of simulation and theoretical calculation results.(4)A mechanical prototype is manufactured,a reasonable new structure redundant parallel manipulator prototype control system was set up,the control scheme was developed,and the motion control was carried out.The results show that the manipulator is stable and reliable during the operation.