Research On Trajectory Planning For Irregular Intersecting Curve Based On 6R Industrial Robot

The industrial robot has been regarded as the key developing field in the ?Made in China 2025? planning. Industrial robot with six degree of freedom(6R industrial robot) can be widely used in the field of oil pipelines, shipbuilding industry, etc. At present, it is necessary to build models and teach by demonstration when welding the intersection curve by industrial robot, which leads to low welding efficiency. By building a general mathematical model of the irregular pipe intersection curve and studying the motion trajectory of complex curved surface, the welding quality and productivity can be remarkably improve, and thus has important theoretical and practical significance.Firstly, the connecting rod coordinate of 6R industrial robot is built with the robot D-H parameter, and the forward-inverse kinematics solution is calculated by the D-H parameter method as well. Aiming at the problem that D-H parameter method has multiple solutions for the inverse kinematics, a novel method which combines D-H parameter method and geometrical method is proposed. In this method, the first three joints which control the robot position are solved by means of geometrical method, and the last three joints which control the robot orientation are solved through D-H parameter method. As a result, the problem solving process is simplified and the computation complexity is reduced. And then, the derived results are simulated and verified on Matlab platform, and the workspace of 6R industrial robot is further analyzed.Secondly, the trajectory planning of joint space and Cartesian space is investigated. The large error problem caused by choosing a single axial increment is solved by applying the improved arc interpolation algorithm. The relationship between terminal joint and each joint angle is also analyzed. In order to effectively control the welding torch pose, an irregular intersection curve model is built in this thesis, and then the welding torch pose is planned by the angle bisector of two planes. Meanwhile, based on three asymmetrical points of the intersection curve, a welding torch position interpolation algorithm is proposed. This method solves the contradiction between the number of teaching point and precision, which simplifies the teaching procedure and improves the working efficiency. Furthermore, simulation results demonstrate that the proposed trajectory planning method can precisely control the position and orientation of welding torch.Finally, this thesis has used CAPC controller of GOOGOLTECH as hardware platform, VS2010 and OtoStudio as software platform to build the experimental platform, and verified the trajectory planning of straight line, circular arc, and complex surface. The experimental results show that the trajectory planning method, which can be determined by any three points on the intersection curve, is entirely feasible and easy to operate. The trajectory planning method proposed in this thesis has important theoretical significance and application value...