H. Dathe and R. Gezzi
The authors investigate some properties of closed planar motions. For practical applications such as in biomechanics, the Steiner circle reduces to a straight line. After the mathematical study of the problem, finally, they show how the results can be applied to experimentally measured motions. The most important part of this motion is described as a double hinge driven by the hip and knee angle, which is a simple model for a planar motion. They conclude that the Steiner line allows us to visualize a selected direction of motion under consideration.