Study On Robot's Absolute Accuracy Calibration Based On Distance Error Model

The general visual measuring robot system based on stereo vision is one of the significant engineering fields of the vision measuring technology applications. The system is mainly composed of an industrial robot and a stereo vision sensor. Besides inheriting the advantages of vision measuring technologies, such as non-touch and quickness, it also extends the working space of the sensor and enhances the flexibleness. When using general robot system to measure workpieces, to ensure the system's measurement accuracy, every part should be calibrated. The most difficult step is the calibration of the robot, i.e. establishing the correct mapping from the joint variables to the position and rotation of the end-effector when robot is at any posture. Many developed countries have done a lot of research on robot's calibration. The accuracy of robot has improved greatly, and many corporations have established their own general measuring robot system. The research in this field is at the primary stage in our country, and most robot systems are manufactured by foreign companies.The research, a branch of the robot calibration, mainly focuses on the robot's absolute accuracy calibration. The main contents are as follows:1. By establishing correct robot's kinematics model and using robot's differential kinematics model, I have deduced the relationship between absolute accuracy and link parameters'error.2. I analyzed distance error model, deduced the relationship between distance accuracy and absolute accuracy, established error amendment equations and gathered data.3. After studying the error equations'stability and using total least square method to calibrate the robot, I drew a conclusion by analyzing the experiment results.4. After analyzing the results of the experiment, I pointed out some defects in the process of calibration that needed improving.