Facing The Robot With The Tangential Performa-nce Enhancement Research On Machining Pos-ture Optimization And Smoothing Algorithm

Industrial robots are widely used in aircraft automation assembly because of their high flexibility,high efficiency and low cost.However,due to the influence of the structure of the series robot itself,the stiffness performance is poor,which affects the machining precision of the end.This thesis studies the posture optimization and smoothing algorithm of the robot's tangential stiffness,which is based on the robot maching system with an extra 7th axis,considering adjustment of the tool coordinate system and the diversity of the inverse kinematics' solutions.Firstly,the KUKA KR360-2 robot is used as the research object.The coordinate system of the connecting rod is established by D-H method,and the kinematics equation is solved and eight the inverse solutions are obtained.The Jacobian matrix of the robot is solved by vector product and differential transformation method.Secondly,the traditional static stiffness model of the robot is established,based on which the stiffness of the connecting rod is assumed and the influence of the compensation stiffness matrix is neglected.The evaluation index of the tangential stiffness is presented.The influence of the joint angle on the index is analyzed.The rationality of the stiffness evaluation index is verified by simulation.According to the characteristics of the holes' distribution,the posture optimization and the smoothing algorithm of the robot with tangential stiffness enhancement are proposed.Firstly,the aim of the genetic algorithm is to optimize stiffness of the first and last points by using the position of the base in the moving platform,the rotation angle of the tool coordinate system and the diversity of the inverse kinematics' solutions as variables.Then,according to the posture of the first and last hole,use the quaternion interpolation to do the smoothing process,to complete all the postures' optimization.Finally,the design example shows that the algorithm is effective for improving the processing efficiency and machining precision of the robot by comparing the posture of the robot with the change of the joint angle,the stiffness index and the end tangential deformation before and after the optimization and smoothing.