Kinematic Calibration Of A 2-UPR-RPU Parallel Manipulator

Parallel mechanism has advantages of high stiffness, high load capacity etc. For these reasons, it plays an extremely important role in the industrial fields. However, the limitation of accuracy often hinders the development of parallel mechanism. Nowadays, the problem of the positioning precision for the parallel mechanism is still an important subject.The thesis focus on a 2- UPR- RPU parallel mechanism, based on the analysis of the kinematics, the kinematics calibration method was studied, in many industrial occasions, effectively improve the absolute positioning accuracy of the robot, mainly includes the following contents:According to parallel mechanism, by determining the relationship between the branches, using closed-loop vector chain organization ideal kinematic model is deduced, the relationship between positive and negative solutions as well as the position of institutions by the MATLAB software to carry on the positive and negative solution of the cross validation, and for the next stage provides a reliable guarantee for the accuracy of the calibration.Based on the characteristics of the institution itself exists, through the analysis of the error sources of institutions, set up agencies reference points including geometric parameter error at the end of the moving platform error model. Again through the error model of error separation, isolating can compensate the error and error compensation.On the premise of contains geometric parameters error model, the first 2- UPR- RPU parallel mechanism was carried out by the zero error calibration study, using a laser tracker on the zero error of parameter identification, and its compensation to the controller to complete zero calibration, using the computer to complete the simulation of the method, which laid a foundation for the kinematics calibration after.Next traditional kinematics calibration was carried out. Based on linear perturbation method to the institutions established error model, the institutions set up by using the least square method contains 21 items of geometric parameter error parameter identification model, using built parameter identification model recognition error value of geometric parameters, and through the compensation method of correction system input error compensation, finally the computer simulation verify the correctness of the calibration algorithm.Finally, a new and simple and effective calibration method was used. The name is Non-parametric Calibration method. The principle and process of a numerous parameters calibration method, using the method of 2- UPR- RPU parallel mechanism, Non-parametric Calibration method and the traditional kinematics calibration methods are compared, and illustrates the applicable range of the two and their respective advantages.In this paper, the research on 2- UPR- RPU parallel mechanism as well as other less degrees of freedom parallel mechanism is widely used in industrial field and in the future is of great significance.