Motion/force Transmission Analysis And Optimal Design Of A Class Of Parallel Manipulators With3Degree Of Freedoms

This paper has described and optimized the motion/force transmission of1T2R parallelmechanisms based on LTI, which is proposed by Liu. The main work and research results are asfollows:Motion/force transmission index system has been defined. When it comes to calculate thevalue of potential maximal power, the existing method do not consider the applied point, i.e.neglect the fact that transmission wrench screw do not across joint center point. In the view ofabove questions, this paper propose an opinion to change the applied point of wrench screw, anda series of formulations is presented to confirm the feasibility. Thus, the physical meanings andcalculation model are both fixed. Input transmission and output transmission should bedistinguished when describe the performance of PMs. Although the calculation model is the same,the physical meanings of elements included in the expression are different, which can be obtainedthrough reciprocal product calculation of twist and wrench screws of PMs’joints.The constraint formulations of joints’ position with respect to reference coordinate areestablished through analyzing the features of PMs’ structure. Thus, the mapping between inputmember and output member is defined, through which Jacobian matrix can be obtained. Jacobianmatrix has already extensively been applied to evaluate the performance of various type of seriesmechanisms and parallel mechanisms, and can describe the singularity poses of mechanismsprecisely. The accuracy of motion/force transmission index can be confirmed by comparing thedata obtained by Jacobian matrix to motion/force transmission.The instantaneous motion/force transmission performance and the ranges of workspace ofPMs can be described by motion/force transmission index, through which optimal type selectionand dimensional synthesis of PMs can also be completed. Optimal type selection, means todetermine the best type according to the requirements of practical engineering application amongseveral PMs which own similar type and dimension. Dimensional synthesis, means to optimal thegeometric dimension of a given PM according to several assigned performance indices.This paper enriches the design theory of robotics, also is helpful to prompt the industrialapplications of robotic technology.