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Instantaneous Centre Rotation for spinal motion

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  • Instantaneous Centre Rotation for spinal motion

    Dear All

    We have a CA6000 machine for measuring spinal motion.

    It actually measures skull relative to thorax or thorax to pelvis.

    The output is a stream of co-ordinates x,y,z and three angles (as well as
    velocity and acceleration data) in text format.

    I have written a set of Excel macros to calculate from the sagittal plane
    data (x,y and theta) the Instantaneous Centre Rotation. However this
    involves a calculation that involves arctangent, which Excel handles badly.

    Can anyone suggest an easy way to carry out these calculations?

    Does anyone have standard routines already written for this?

    Many thanks in advance


    Euro Ing Edward Draper PhD BSc CEng MIMechE IPEM
    Principal Clinical Bioengineer
    Division of Surgery, Anaesthetics and Intensive Care
    Imperial College School of Medicine

    Tel: +44 (0) 181 746 8312 Fax: +44 (0) 181 746 8787
    Mobile: 0385 785369 email:

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