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Closed chain dynamics models

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  • Closed chain dynamics models

    Dear Biomch-L,

    I have successfully created open chain rigid body models of the human body
    (dynamics) to study the biomechanics of movement. Such models have been used to
    study the dynamics of cricket bowling and throwing. I am a little handicapped by
    the software that I am using, but I have now turned my attention to the golf
    swing. The difference is that this needs to be modelled as a closed chain link
    segment model - the hands and the club form a closed chain. I have been using
    spherical constraints to connect the segments (distal point coincident with the
    proximal point of the adjacent segment) and 3D rotation lock constraints to
    describe the angular orientation of the segments (Euler angles). This works well
    for open chain systems, but in closed chain systems, the number of constraints
    exceeds the number of degrees of freedom, and the system is overconstrained, and
    the equations cannot be solved by the software. Generally, the number of
    constraint equations exceeds the number of degrees of freedom by 3 for simple
    closed chain systems using the above mentioned choice of constraints.

    My objective is to solve dynamics models of such closed chain models as golf and
    olympic weight lifting. I would appreciate any information which would help me
    resolve this matter.

    Dr. Rene' Ferdinands
    Department of Physics &
    Electronic Engineering
    University of Waikato
    Private Bag 3105
    New Zealand

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