Butterfly became an independent stroke and made its Olympic debut at the 1956 Melbourne Games. The stroke is contested over distances of 100m and 200m. In swimming, the term “medley” refers to events ...

Butterfly is a difficult stroke to swim as it needs both stamina and style. The movements you need to make, however, are not difficult because you will have done many of them before in other strokes.

The robots are called “butterfly bots,” because their swimming motion resembles the way a person’s arms move when they are swimming the butterfly stroke.