Elastic dynamics modeling and analysis for 6-RSS parallel robot with joint clearance
To improve the accuracy of the dynamic model of the six-degree-of-freedom parallel robot in space,taking the 6-RSS parallel robot(R:rotating joint,S:spherical joint)as the research object,a dynamic modeling method combining the elastic deformation of the branch chain and the random change of the joint clearance was proposed.According to the geometric structure and initial state of the parallel robot,the kinematics analysis was carried out under ideal conditions.The mathematical statistics principle and symbolic function were used to establish the kine-matic model of the revolute joint with clearance and spherical joint with clearance.The bar virtual length and the collision contact force at each joint were calculated.Combining the bar virtual length,the collision contact force and the elastic dynamics model,the elastic dynamics model of the 6-RSS parallel robot with joint clearance was estab-lished.Finally,the reasons for the errors of the elastic deformation of the branch chain and the joint clearance under different conditions and the reasons for the combined errors of the two were analyzed.The results showed that the improved dynamic modeling method fully considered the coupling and instantaneity of the elastic deformation of the branch chain and the joint clearance,and was more accurate than other dynamic modeling methods.