Identification of Lower Extremity Dynamics During Snow Skiing

Abstract

Severity of the skiing environment can be interpreted only through the response of the lower extremity to the excitation of the environment. Identification of a linear, four degree of freedom, lower extremity ski torsion model was undertaken. A new procedure is introduced for filtering the deterministic trends from the random torsion data measured between the boot and ski during skiing. Trend removal is necessary for identification. The objective function for the identification was the square of the difference between the spectrum of the trend-removed torsion data and the spectrum of the model torsion. Following identification, the model responses predicted during two authentic skiing falls were computed, thus permitting a comparison of their relative severity.