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---+Reading Notes

Scott L. Delp, Frank C. Anderson, Allison S. Arnold, Peter Loan, Ayman Habib, Chand T. John, Eran Guendelman, and Darryl G. Thelen. _OpenSim: Open-Source Software to Create and Analyze Dynamic Simulations of Movement_. IEEE Trans. on Biomedical Engineering, Vol. 54, No. 11, November 2007.

[[http://nmbl.stanford.edu/publications/pdf/Delp2007.pdf]]

---++Summary

Presents OpenSim, an open-source biomechanic simulation software available at [[https://simtk.org]]. The paper provides a brief overview of the OpenSim platform but focus more on SimTrack, a plug-in aimed at tracking motion-captured data.

SimTrack works in 4 steps:
   1. _Scaling_. A generic muskuloskeletal model is scaled to fit measured data (global body mass and mocap markers)
   2. _IK_. Inverste kinematic is used to let the scaled model track the mocap data.
   3. _RRA_. A residual reduction algorithm is used to ensure that the modeled masses and the tracked accelerations match the measured ground reaction forces and moments.
   4. _CMC_. Computed muscle control generate muscle activation to produce coordinated muscle-driven simulation of the movement.

A sample case study is given, where a stiff-knee gait is tracked, a chirurgical procedure is simulated in OpenSim, and then compared with results from the actual procedure.

---++Comments

   * I don't understand equation 2, that looks quite simple at first glance. Ran it by Stelian and he finds it quite fishy too.
   * The most interesting part, step 4 _CMC_, is not very precisely described. It is mentioned that a static optimization criterion is used to distribute forces across synergistic muscles.
   * Another muscle model is given here, I should investigate.
   * I should check the Physiome Project, that outline the challenge of building a human neuromuskuloskeletal model. (See ref 78)
   * It is mentioned that Thelen and Anderson were able to drive a 21 DOF, 92 muscles model to track gaits, with simulation times of 30 minutes for a half-cycle (see ref 25).

-- Main.PhilippeBeaudoin - 13 Feb 2009


-- Main.PhilippeBeaudoin - 11 Mar 2009
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Topic revision: r1 - 2009-03-11 - PhilippeBeaudoin