Research And Applications On Robot Calibration Algorithm Based On Draw-wire Encoder Measurement System

Nowadays,robot was widely used in all kinds of fields,transit from replacing human labor simply to high accuracy application fields.Robot was required high position precision.It is necessary to develop robot calibration and measurement system to improving robot accuracy.According to several difficulties during industrial robot calibration,such as high cost of measurement system and working environment.A kind of calibration and measurement system based on draw-wire encoder was designed,which can realize geometrical parameter calibration of industrial robot and 3D position measurement.The following is the main contents of this paper:(1)Robot calibration algorithm was established based on calibration system including parameters of position and orientation.The algorithm solved the problem that the length of the cable is not a straight line,by using several parameters of position and orientation to represent the position.Kinematic error model of robot was established according to D-H model,the least square method was used to identify the geometric parameter of robot.The correctness and universal of the algorithm was verified after simulation.(2)Geometric parameter calibration of calibration system based on closed-loop vector chain was established.Measurement precision of calibration system is studied.Sensibility of calibration algorithm to some kinds of error was also studied.Compensation of errors was presented,which improved the accuracy of calibration system.(3)Based on the research of calibration system.The structure layout of the measurement system was established by using of the combination of calibration system.Measurement algorithm was also presented,which can meet the demand of spatial measurement after easily initial position calibration.(4)The correctness of algorithm which proposed in this paper was proved by experiments,such as calibration algorithm of the calibration system,industrial robot calibration system algorithm and measurement algorithm.First of all CMM was used to validate the accuracy of calibration system.Then the robot calibration experimentation was carried out by using ER30 robot.Finally,accuracy verification experimentation was conducted by using KUKA robot,which proved the correctness of measurement algorithm.