Determining motor skill characteristics with a reduced model approach

The kip is a fundamental gymnastic movement performed on a variety of gymnastic apparatus at all levels of competition. We analyze the kip with a reduced model approach consisting of a pendulum and 3-link system. Our simulations have shown that a variable length pendulum is sufficient for modeling the dynamics of an expert gymnast´s center-of-mass without considering the complex parameters of the 3-link system. The optimized pendulum model can generate kip pattern variations which are evaluated based on the center-of-mass and 3-link system´s total energy. A comparison of the performances of robot, simulator and human expert identifies (1) body arching during the forward swing, (2) a quick piking movement, and (3) grip adjustment during the backward swing as characteristics common to success. These results suggest a guideline for performing the kip successfully