Elastodynamics And Error Analysis Of Planar 2-DOF Redundant Actuated Parallel Mechanism

Planar 2-DOF redundant actuated parallel mechanism consists of a planar 5R mechanism and a redundant drive branch,which is usually employed as a positioner in the trajectory plane.This research investigated various factors on the influence of output precision,including the kinematics,rigid body dynamics,elastodynamic and error factors,etc.The main contents are as following.The research carried out kinematic analysis of the planar 2-DOF redundant parallel mechanism,and solved the problem of the mechanism reversing,then the velocity and acceleration can be obtained.Based on establishing the rigid body dynamic mode,driving force and constraint force of the mechanism can be calculated.Meanwhile,driving force of redundant actuation is optimized and is verified in the Adams simulation environment.The elastic dynamic model of the mechanism was established.First,the elastic dynamic model of the flexible rod was established based on the finite element method and the Lagrange equation.Then,the elastic dynamic models of each member were integrated to obtain elastodynamic model of the planar 2-DOF redundant actuated parallel mechanism,the natural frequency of the mechanism can be obtained by solving the elastodynamic equation,and the influence of the section size of the rod on the natural frequency of the mechanism was also analyzed.Finally,the dynamic model of the mechanism was verified by the experiment of natural frequency.The study established the geometric error model of the mechanism,the joint gap error model and the over constraint error model,analyzed various factors on the influence of output precision,including geometric error,clearance of rotary pair and over constraint error caused by parallelism error.Finally,the elastodynamic model of the mechanism was solved,and the elastic error of the mechanism was analyzed on the condition of over loading and different structure sizes.In the last part,a calibration model of the mechanism error was established,and the kinematics calibration experiment of the mechanism prototype was carried out,the compensation of geometric error of the mechanism was analyzed,and investigated the changes of the output precision before and after calibration.