Research On Error Analysis And Motion Compensation Of Delta Parallel Robot

With extensive application of industrial robots,their performance requirements are gradually improving.How to reduce the error of robot has been the focus of the study of the majority of scholars.This paper researched on Delta parallel robot error analysis and compensation.Firstly,the kinematics model is the basis of robot control and error analysis.According to the standard structure,the positive and inverse solutions of the kinematic position of Delta robot were obtained by spatial geometric relationship.On this basis,the Jacobian matrix of the robot was derived and solved.For the structure with error,the original error parameters were expressed by the geometric variables.The mathematical model of robot error was established by deriving the space vector chain and obtaining the error transfer coefficient matrix between the original error of parameters and the error of end operator.Through the virtual prototype software Adams,the standard structure of Delta robot and the structure with error were simulated and analyzed,respectively.The acquired results were consistent with the mathematical model.On this basis,the influence of the original error of parameters on the error of end operator was analyzed.Secondly,a set of monocular vision based error compensation method was proposed.Based on the theory of visual imaging,the relationship between the camera coordinate system and the robot coordinate system was determined by combining the monocular camera with the calibration plate,and the accuracy of the robot was measured.The method of spatial interpolation was used to predict the error value of the robot in the working space.The method assumes that the robot error vector in the working space has certain continuous and smooth characteristics.By measuring the error information of each node in the specified space area beforehand,the motion trajectory of robot can be derived,and the error can be predicted by interpolation calculation.According to the predicted error,the end operator of the structure was compensated by using the Jacobian matrix in terms of the robot.The kinetic model was used to simulate the error compensation method,and the feasibility of the error compensation method was verified.Then,in order to verify the effect of error compensation method,the experimental prototype was set up.The error compensation method was integrated into the host computer by Labview,and the combination of monocular vision and calibration plate was used.The error compensation of prototype was carried out by using the derived Jacobian matrix and the spatial interpolation method,which effectively improves the accuracy of the robot.Finally,based on the hypothesis of KED theory,a two-node 12-DOF space beam element was proposed.The finite element method was used to analyze the special structure of quadrilateral driven arm in parallel robot,and the elastic dynamic equation of the branch was deduced.The control equation was finally solved by using the NEWMARK integral method and the elastic error of the robot under a specific motion trajectory was calculated.The elasticity error of the robot was reduced by introducing the Fourier function correction.Finally,the influence of the cross section parameters on the elasticity error was analyzed,which provides the reference for the engineering application.