Research On Error Compensation Technology Of Industrial Robot Based On Planar Constraints

With the rapid development of robot technology and the growing of its application field, the higher positioning accuracy is required in industrial production. Because of the manufacturing and assembly error, the flexible error of joint, and the transmission error of the gear etc, the positioning accuracy is currently low. It seriously affected the application and development of robot in the field of high precision processing and off-line programming, so it is of great significance to analysis the error sources of robot and research on the error compensation technology. By taking the independent research JNPF-6R robot as a research subject in this paper, the error compensation method of robot based on planar constraint is put forward though researching on the error from geometric parameters and gravity effects. The verification experimental is conducted at last.First of all, robot kinematic model is established through the MDH model method, which analyses the relationship between the end positioning of robot and various joint parameters. The function relationship between the end posture error of robot and the kinematics parameters is established based on the principle of differential transformation. It is also called the posture error model which includes geometric parameter error. The correctness of the model is verified by simulation.Secondly, the non-geometric factor which affects the positioning accuracy of robot is researched, and the key research is the elastic deformation of joints because of the gravity. According to the research on the main bearing joint 2 and joint 3, the flexible error model is established and the synthesis end position error model of robot is established through aggregating the flexible error and geometric error together. The compensation experiment is conducted by the open-loop method with the Faro laser tracker as measurement device.Then, according to the open-loop method which requires the expensive measuring equipment, this paper puts forward a simple and inexpensive error compensation method of robot based on planar constraints. The identification model of parameter error is established based on a constraint condition that restricts the robot moving on a plane with higher accuracy. Meanwhile, this paper also presents a measurement method which is based on measuring head to test conveniently through combining the contact measurement system with the robot system. A planar measurement experiment is adopted to validate the effectiveness of this measuring method.Finally, the error compensation experiment is conducted with four plane of calibration block as constraint conditions. The parameter error is obtained by taking the measured data into the error model. The positioning accuracy of robot is improved by compensating the parameter error into the compensation module of robot control software. The average distance precision between the ending tools of robot and constraint plane is reduced from 3.436 mm to 0.878 mm, and increasing by 74.44%. Meanwhile, the interfaces of parameter error identification are designed based on MATLAB/GUI to identify conveniently and visually.