Instructions and Details
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The best way to do this is with a link to: http://creativecommons.org/licenses/by-nc/3.0/ * -------------------------------------------------- * "Simulated muscle fiber lengths and velocities during walking and running" URL: https://simtk.org/home/muscfib_walkrun Publication: http://jeb.biologists.org/content/216/11/2150.abstract? sid=28158300-d50b-4616-a145-8fca9537bd51 Authors: Edith M. Arnold, Samuel R. Hamner, Ajay Seth, Matthew Millard and Scott L. Delp Contact: https://simtk.org/sendmessage.php?touser=451 This document describes what is included in the downloads section this project and how to use these files. IMPORTANT NOTE ON MUSCLE MODELS: A custom plug-in was written to use a two-state (length and activation) muscle model with the Zajac 1989 formulation. This included the ability to use two cubic splines to describe the force-length and force-velocity curves. This model is, for legacy reasons and somewhat misleadingly, called "Thelen2003MuscleV1" in the .osim file. The version of the scaled musculoskeletal model with this model is included for completeness, but is probably un-readable with most versions of OpenSim, so a version with the "Schutte1993Muscle" model is also included. This one will enable the user to visualize the results states file in OpenSim, but this WAS NOT the one used to generate the simulations. This complication was a necessary work-around when I was doing this work in 2011, but has been made obsolete by improvements to the muscle models in more recent versions of OpenSim. For an excellent discussion on the ins and outs of muscle models in OpenSim see the paper below by Matt Millard. Millard, M., Uchida, T., Seth, A., Delp, S.L. Flexing Computational Muscle: Modeling and Simulation of Musculotendon Dynamics. Journal of Biomechanical Engineering, vol 135. Zajac, F. E. (1989). Muscle and tendon: properties, models, scaling, and application to biomechanics and motor control. Crit. Rev. Biomed. Eng. 17, 359-411. This download includes: 1. Arnoldetal2010_2Legs_v3_hplmuscles_240.osim The generic musculoskeletal model used for this study. This model is based on the model described by Arnold et al. 2010 (ref below). It uses the Schutte1993Muscle model formulation. Several changes were made to the original model to make it appropriate for the demands of this study. See publication for description of these changes. Please cite appropriately. Arnold, E. M., Ward, S. R., Lieber, R. L. and Delp, S. L. (2010). A model of the lower limb for analysis of human movement. Ann. Biomed. Eng. 38, 269-279. https://simtk.org/home/lowlimbmodel09 2. A folder for each one of the five subjects in the affiliated publication. In each folder you will find: 2.1 The generic OpenSim model described in (1) scaled to the subject. There are two versions one that was used for the actual simulation (naming convention below, this will not open in the OpenSim GUI) and a second that will open in the GUI and can be used with the states file to visualize the motion. The naming convention is as follows: subjectNN_scaled_AHv3_FV1D_Vx15_ad0104_pf10_2F.osim AHv3 = This was version 3 of a hybrid model that (Edith) Arnold and (Sam) Hamner created for their PhD work. FV1D = A 1 dimensional force velocity curve was used (i.e. doesn't scale with activation) Vx15 = maximum fiber velocity set to 15 optimal fiber lengths/second ad0104 = activation and deactivation constants were 0.01 and 0.04 pf10 = plantarflexor tendon stiffness set to 10% strain at maximum isometric force 2F = Force was multiplied by 2x from the generic model. See discussion in publication for background and justification. 2.2 A folder with results for each speed studied. The naming convention is gaittype_speedtrial_results. eg. Run_20001_results was the subject running at 2.00 m/s, trial 01 Within each folder there are many files with results in tab delimited format. 2.2.1 *_states.sto: Forward simulation results with all states (generalized coordinates, muscle activations, and muscle fiber lengths) angles are in radians. If you want to visualize the simulation, load this file with the model in the OpsenSim application. 2.2.2 *_states_degrees.mot: same as above but with degrees instead of radians. legacy OpenSim format. 2.2.3 *_Actuation_*: Results from the actuation analysis package in OpenSim. 2.2.4 *_MuscleAnalysis_*: Results from the muscle analysis package in OpenSim. This is where the meat of the published results come from.