Synthesis And Performance Analysis Of Three Degree Of Freedom Decoupling Parallel Mechanism

Parallel mechanism has the advantages of high precision and high strength,but the strong coupling makes the mechanical analysis and control of the mechanism relatively difficult.In this paper,the decoupling characteristic of the mechanism was studied for the strong coupling of the mechanism.A type of 1T2R parallel mechanism with triangular decoupling characteristics was obtained through the theory of type synthesis.One of the mechanism was studied in terms of mechanism freedom calculation,kinematics,statics,and dynamics.Finally,the mechanism was applied to the satellite antenna mount and studied theoretically.Firstly,the decoupling characteristics of the triangle decoupling mechanism were studied.Through the decoupling property and the rotational freedom condition,the degree of freedom of each branch was obtained.The synthesis of each branch was completed by the screw theory.By combining the branches,different mechanism configurations were obtained that meet the requirements.The PU+PRU+PUS parallel mechanism was selected as the research object and the degree of freedom was calculated.The kinematics analysis of the mechanism was completed.The position,velocity and acceleration equations of the mechanism were obtained.Numerical simulation and simulation verification were carried out.At the same time,the Jacobian matrix of the mechanism was obtained as the lower triangle,which verifies the correctness of the triangle decoupling characteristics of the integrated mechanism in this paper.In the analysis of the degree of freedom of the mechanism,the mechanism was found to be an over-constrained mechanism.For the static uncertainty of the over-constrained mechanism in the static analysis,the rods are independently analyzed by the method of dismantling.By analyzing the redundant parallel constrained screw of the mechanism,the virtual motion pair was obtained to eliminate the mechanism over constraint.Based on the small deformation theory,consider the deformation coordination equation of the elastic deformation of the member in the direction of the virtual motion pair,and complete the static analysis of the mechanism with the balance equationBy establishing the closed-loop vector equation between the branches of the mechanism,the position,velocity and acceleration of the centroid of each member were obtained,and the mapping matrix between the centroid of each member and the kinematic parameters of the moving platform was established.Based on the principle of virtual work,the inverse dynamics model of the mechanism was established.The driving force of each branch during the motion of the mechanism was obtained and numerically simulated.The simulation of the mechanism dynamics was completed by establishing the Adams model,which verified the correctness of the inverse dynamics modelFinally,PU+PRU+PUS mechanism was used to adjust antenna attitude to ensure alignment between antenna and satellite.Considering the constraint relationship between the satellite and the antenna,after the new kinematics parameters of the mechanism moving platform was obtained,the motion and force of the original moving platform was replaced.The kinematics and dynamics equations of the satellite antenna system was obtained based on the kinematics and dynamics equations of the mechanism.The Adams software was used to verify the feasibility and rationality of the application.