Simulation of turns with a 3D skier model

Abstract

The skier was modeled by seven rigid segments: trunk, left and right thighs, shanks, and skis. The segments were connected by four rotational joints in the knees and ankles and two spherical joints in the hips. The user can specify the slope, the track of the right ski, and driving constraints for right ankle, right knee and both hips. Further, a balance condition determines the inward lean and consequently the edging angle of the right ski. The ground contact of the left leg yields a closed loop condition determining the left knee angle. The left ski is rotated to remain on the snow surface, fixing the left ankle angle. The resulting constrained Newton-Euler equations of motion were formulated in descriptor form. Their numerical solution yields the reaction forces and moments. For validation, the results are compared with an inverse dynamic analysis of a run of an elite skier.