A Multisegment Dynamic Model of Ski Jumping

in Journal of Applied Biomechanics
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This paper presents a planar, four-segment, dynamic model for the flight mechanics of a ski jumper. The model consists of skis, legs, torso and head, and arms. Inputs include net joint torques that are used to vary the relative body configurations of the jumper during flight. The model also relies on aerodynamic data from previous wind tunnel tests that incorporate the effects of varying body configuration and orientation on lift, drag, and pitching moment. A symbolic manipulation program, “Macsyma,” is used to derive the equations of motion automatically. Experimental body segment orientation data during the flight phase are presented for three ski jumpers which show how jumpers of varying ability differ in flight and demonstrate the need for a more complex analytical model than that previously presented in the literature. Simulations are presented that qualitatively match the measured trajectory for a good jumper. The model can be used as a basis for the study of optimal jumper behavior in flight which maximizes jump distance.

Mont Hubbard and Robin L. Hibbard are with the Department of Mechanical Engineering at the University of California, Davis, CA 95616. Maurice R. Yeadon is with the Biomechanics Laboratory at the University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4. Andrzej Komor is with the Institute of Sport, Warsaw 01-809 Poland.