| Industrial robot is an important part of modern equipment manufacturing industry. 6-DOF(degree of freedom) industrial robot is one of the most widely used industrial robots. 6-DOF industrial robots, which are mainly applied in the assembling, painting, transporting, palletizing, welding, etc, can improve the productivity, guarantee the quality of the production and ensure the safety of the process. The shortage of the reliability and the absolute positioning accuracy of 6-DOF industrial robot restricts its application in the field of the high precision. Therefore, in this paper, the reliability analysis and kinematic calibration are studied, and SR165 industrial robot is used as the study object. In reliability analysis aspect, we do the qualitative analysis to the SR165 industrial robot system based on the fault data during debugging stage. In kinematic calibration aspect, in order to reduce the terminal positioning error and to improve the absolute positioning accuracy, we establish two methods and implement the experiment with a SR165 industrial robot.The paper includes two sections.We discuss the reliability analysis of the industrial robot system in the first section. In this section, we sort out the fault data which was collected from the factory and divide the SR165 industrial robot system into 7 subsystems. Then, we do the preliminary analysis to the industrial robot system from the point of the subsystems and the fault responsibility. We do the reliability analysis using fault tree analysis method with the fault data of the electrical control system, whose fault date is the most comprehensive. According to the fault causes, we propose some improvement measures to improve the reliability of the industrial robot system.We discuss the kinematic calibration of the industrial robot in the second section. In this section, firstly, we analyze the structure of the SR165 industrial robot. Considering the advantages and the disadvantages of the D-H model and the MD-H model, the robot kinematic model combining the D-H model and MD-H model is established by using homogeneous transformation method. The kinematic positive solution of SR165 industrial robot is also deduced.Secondly, after analyzing the error sources of the industrial robots, we put forward a kinematic calibration method aiming at the overriding error-the error of the geometric parameters to improve the absolute positioning accuracy. The error model of the SRI 65 industrial robot, i.e. the function relationship between the error of geometric parameters and the error of the end position, is obtained by solving the differential kinematic equation. Thirdly, we propose two parameter identification methods-the least square method and the Levenberg-Marquardt method in order to solve the error model of the SR165 industrial robot. With MATLAB, the kinematic model, the error model and the two algorithms are implemented. We carry out the simulation of the kinematic calibration of the SR165 industrial robot. The least square method and the Levenberg-Marquardt method are applied to identify the 24 geometric parameters respectively. Comparing the simulation results, we find that the Levenberg-Marquardt method is more suitable than the least square method for the kinematic calibration.Finally, based on the success of the simulation, we conduct the kinematic calibration experiment. We propose three measurement schemes and compare their feasibility. The direct measurement method with the laser tracker is the most suitable scheme. After measuring, identifying and verifying, the positioning error of the SRI 65 industrial decreases sharply. |
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