Methodology And Practice Of Continuous 3R Oblique Axis Non-spherical Wrist For Spraying Painting Robot

In order to develop a wrist with 3 rotary DOF for spraying painting robot, this dissertation deals with the key issues relevant to novel structural design, kinematic analysis, dynamic modeling, kinematic calibration and control system of an oblique axis non-spherical wrist with 3 continous rotary motion systematically. As a result, a prototype machine of continous 3R oblique axis non-spherical wrist has been developed. The following research achievements have been completed.Utilizing the varying-drive-direction features of bevel gear system, a hollow oblique axis non-spherical wrist with 3 continous rotary DOF, constructed with bevel gears of 60o reference cone angle has been proposed. All tubes such as paint tube, solvent tube, and shaped-air tube and so on, which go through the wrist, can be protected from being knotted or broken when the wrist is rotating. With cramped construction, small inertia and great flexibility ratio, the wrist can be in any orientation in three-dimensional space and be suitable for spraying painting robot.Based on the theory of graph representation, the canonical graph representation of the continous 3R oblique non-spherical wrist is setup, and links of the wrist are divided into carriers and carried links. At the same time, the concept of virtual link is introduced, and the generalilzed inertia forces of carried links are divided rationally according to their motions. Then, the generalized inertia forces provoked by virtual links and carried links are derived with Lagrange Equation. At last, an efficient and systematic dynamic equation of the wrist is developed. In the dynamic equation of the wrist, the coupling effects of carried links can be identified individually and systematically.The control system of 6R spraying painting robot with oblique axis non-spherical wrist is built with commercial PLC and machine controller MP2300. And the kinetic control programs for the wrist are developed.Based on the D-H parameter model, the all-parameter-error-identification model of the continous 3R oblique axis non-spherical wrist is setup, and computer simulation is made. In the end, based on the prototype machine of of continous 3R oblique axis non-spherical wrist, the experiment of kinematic calibration of the wrist is accomplished by using the data measured with FARO laser tracking systems. Experiment results confirmat that the the all-parameter-error-identification model of continous 3R oblique axis non-spherical wrist is right and precision compensation is effective.The above outcomes have been used for the development of a prototype machine of continous 3R oblique axis non-spherical wrist. After kinematic calibration, the spatial positioning accuracy of the TCP at the end of the wrist is 0.104 mm. It can satisfy the requirements for the working of car body spraying painting.