The designs of mechanical machines often demand a particular form of movement (such as the rotation of a motor) to be translated into a different form of movement (such as the back-and-forth of a windscreen wiper). Depending on the application, there are a manifold of demands on the exact form of the resulting movement, and the way in which the power is transformed. Joint mechanisms, made of rods and movable connections, are today created mainly with the help of computers, in order to match the the very specific requirements as closely as possible.
A particular challenge is for example the transformation of a rotation into an exact or approximately straight-line movement. The animation shows a classic mechanism from Tschebychev, who created a straight course with a good approximation over a long stretch. If you move the right slide bar upwards, you can see how such a mechanism can, for example, be used for a walking robot.