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Finding the functional centre of rotation

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  • Finding the functional centre of rotation

    Dear all,

    I have been a long time user of PECS with Vicon Nexus to integrate advanced kinematics fitting methods in our routine processing for gait analysis in Melbourne. I also spent quite a bit of time testing different algorithms to find functional centre of rotations and evaluate these against freehand 3D ultrasound or EOS bi-plane imaging.

    Nexus 2 does not support PECS anymore but provides a new way to interact with Matlab. It also provides a rigid body kinematics fitting called OCST.
    I played a bit with those new tools and realised the combination of these made it feasible to share some of the code I developed in 'one script'.

    So, for those interested in functional centre of rotation, you will find here:

    the Matlab script to run a geometrical functional calibration (concentric spheres fit, from Cappozzo 1984 'centroid' and Leardini 1999 'concentric spheres') and the Centre Transformation Technique (described in Piazza 2004 and named CTT in Ehrig 2006).

    You will find here:
    a succinct help on how to use the matlab script with Nexus 2 (assuming you have read the Nexus help first).

    Hope the script may be useful for you to either understand how to interact with Nexus 2 from Matlab or find the functional joint centres. Don't hesitate to contact me if you find a bug in the script or you have ideas on how to improve it.