| This structure type ,that the robot is the moving carrier of the stereo vision sensor, not only keeps the vision measuring technology's characteristics of non-contact and quickness, but also enhances the flexibility of the whole measuring system. In order to ensure the measurement accuracy of the system, 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.The main research work and creative research made by this thesis are summarized as follows:1. According to the robot of our lab, all kinds of coordinate systems are presented in detail. The communication mode is introduced, and the communication procedure is programmed.2. The D-H kinematics model is established, and the forward and inverse kinematics is analyzed, then some examples are presented. The differential kinematics problem is analyzed detailed, which is the theory foundation of robot geometrical calibration.3. Robot link parameter solving model based on distance constrain condition namely error distance minimizing constrain is put forward. The solution procedure of distance model is deduced in detail, and both distance accuracy and distance error are used to judge the precision of robot.4. For the first time the method of virtual base coordinate system, which belongs to robot geometric parameter calibration method, is presented. This method not only realizes fast detection, but has high accuracy.5. According to three geometrical calibration methods, the calibration experiment system is established. The data of robot and tracker are collected individually, and calibration results are educed by solving equations. The experiments prove that the robot's distance accuracy enhanced nearly upon two times after calibration.6. Generalize experiment experience and put forward several questions which need pay attention and improve in the process of calibration.
|
PDF Full Text Request