Design And Analysis Of A Reconfigurable Hybrid Mechanism

With the rapid updating of products,Flexible Manufacturing System has been widely used in many industrial fields.Reconfigurable parallel robots generally contain not only the advantages of parallel manipulators,high precision,high stiffness and large load and so on,but also have multiple working modes that is applicable in Flexible Manufacturing System.Furthermore,the reconfigurable function of reconfigurable parallel mechanisms promises them to choose various trajectories in order to reduce driving force/torque and avoid their singularity configurations.Therefore,a reconfigurable hybrid manipulator is presented in this paper,along with exhausted kinematic and dynamic analysis.At first,this paper introduces single degree of freedom reconfigurable platform.To obtain the robots that can meet the proposed requirements,multiple loops single/multiple degree(s)of freedom over-constrained parallel mechanisms are discussed based on screw theory.Thereafter,a serial-parallel hybrid manipulator with three translational degrees of freedom and two rotational degrees of freedom is designed.This proposed novel mechanism’s inverse and direct kinematic models are derived via closure loop equations.The equation for singularity configurations is also sloved.Based on its inverse solutions and spatial searching algorithm,its reachable workspace atlas is obtained.Then the effects caused by different rods are depicted after analyzing its dexterity and stiffness index.Later optimal linkages sets are obtained in the given ranges with reachable workspace and stiffness as the objectives.Assuming qualities of all links are centralized in their centers of mass,the relationship between input forces and external loads is computed through virtual work principle,and the case that the end-effector moves along axis Z is taken as an example to illustrate motion and force changes of driving motors and the moving platform.Due to this manipulator’s special reconfigurable function,a unique end-effector’s trajectory that three translational driving joints and the reconfigurable driving pair are employed alternatively is analyzed in detail and we have obtained its results.At last,three driving motors’ performances are achieved when the reconfigurable driving joint is locked and the moving platform rotates about axis Y.