A Simple 2-dimensional Model of Speed Skating Which Mimics Observed Forces and Motions

Advice about the optimal coordination pattern for an individual speed skater to reach their optimal performance, could well be addressed by simulation and optimization of a biomechanical model of speed skating. But before getting to this optimization approach one needs a model that matches observed behavior. In this paper we present a simple 2-dimensional model of speed skating on the straights which mimics observed kinematic and force data. The primary features of the model are: the skater is modeled as three point masses, only motions in the horizontal plane are considered, air drag forces which are quadratic in the velocity and coulomb type ice friction forces at the skates are included, and idealized contact of the skate on the ice is modeled by a holonomic constraint in the vertical direction and a non-holonomic constraint in the lateral direction. Using the measured leg extension (relative motions of the skates with respect to the upper body) we are able to predict reasonable well the speed skater motions, even if we do not fit for that. The model seems to have the key terms for investigations of speed skating.