Blending tool paths for G1-continuity in robotic friction stir welding

In certain robot applications, path planning has to be viewed, not only from a motion perspective, but also from a process perspective. In 3-dimensional Friction Stir Welding (FSW) a properly planned path is essential for the outcome of the process, even though different control loops compensate for various deviations. One such example is how sharp path intersection is handled, which is the emphasis in this paper. We propose a strategy based on Hermite and Bezier curves, by which G1 continuity is obtained. The blending operation includes an optimization strategy in order to avoid high second order derivatives of the blending polynomials, yet still to cover as much as possible of the original path.