  Automatic welding of tubular TKY joints is an important and challenging task
for the marine and offshore industry. In this paper, a framework for tubular
joint detection and motion planning is proposed. The pose of the real tubular
joint is detected using RGB-D sensors, which is used to obtain a
real-to-virtual mapping for positioning the workpiece in a virtual environment.
For motion planning, a Bi-directional Transition based Rapidly exploring Random
Tree (BiTRRT) algorithm is used to generate trajectories for reaching the
desired goals. The complete framework is verified with experiments, and the
results show that the robot welding torch is able to transit without collision
to desired goals which are close to the tubular joint.
