Research On The Error Analysis And Calibration Of A Parallel Rotary Robot

With the development of modern industry, the requirments of parallel robot performance are rising, especially more prominent in high-precision, ultra-precision robot. The accuracy which as a measure of the working performance of parallel robot has become a major factor restricting its development. There are many ways to improve the accuracy of parallel robot, one common method is to study the robot error characteristics fist, and then targeted for kinematic calibration to improve the kinematics accuracy.This paper mainly aimed at a three-DOF parallel manipulator with mobile platform rotating continuously, in order to improve its motion precision, analyzed the relationship between the structure error and end pose error, to study the robot error analysis and calibration.First of all, select a serial kinematic chain, using D-H method establishes the position equation of the robot end manipulator.Secondly, the possible error about the robot is divided into five categories, and the robot is split into three branches on the basis freedom of movement, in each of the branched chain, using influence coefficient method to establish the error equation,then by the tiny error of linear superposition to get robot error model.Again, defining three types of error evaluation index, through the evaluation index in the space to analy error sources. Found the robot position error sensitivity is high, the position error tropy sensitivity is bad.In addition, analysis of the branched chain shared artifacts and robot concrete structure, classification and merge each of the error term. Eventually we will determine 11 calibration error which is needed, then based on error model and error matrix to set up the accurate calibration model. Found and explained two pairs of coupling error.Finally, the Fletcher method of nonlinear least squares is applied to the calibration model for the simulation calculation to prove the validity of research methods.