Model Making and Modification

This page is for topics related to making and modifying models.

Table of Contents

Viewing and Editing Models in Notepad++

Notepad++ is a free tool that is very helpful for modifying models by directly editing the .osim file. It is available here:

Once a .osim file is open in Notepad++ setting the language to xml will mark up the tags in the file and make it easier to navigate. To do this once, click Language and select XML.

To set Notepad++ to consistently recognize files with the .osim ending follow these steps.

  1. Go to Settings

  2. Select Style Configurator

  3. In the Language: list scroll down until you see XML and select it.

  4. In the box for User ext: type osim

  5. Save and close.

Now Notepad++ will always recognize files ending with .osim and apply the appropriate markup, including separating collapsing levels of objects.

Use shortcuts for collapsing and expanding levels to quickly navigate models. The shortcut 'Alt + number' will collapse everything on the level of 'number'.

Using Existing Models

There are many freely available musculoskeletal models. Some are distributed with OpenSim and others can be found here:

Details about each model can be found in the associated publication, the project page, and in the model file. SIMM models often have details about the uses and limitations of the model in the .jnt or .msl file. OpenSim models have fields for <credits> and <publications> or other comments in line. These can be viewed in the file itself using an XML editor. The details of the <credits> and <publications fields can be viewed in the OpenSim GUI by right-clicking on the model name in the Navigator window and selecting Info.

The following sections are practical details that have come for researchers using publicly available models.


Gait2392 is a 92 muscle, 23 degree of freedom model that is distributed with OpenSim. The maximum isometric force values are not the same as the Delp 1990 model. This model is significantly stronger. The scaling factors between gait2392 and two other sources, Delp 1990 and Carhart 2000 are shown below.

Table contents courtesy of Samuel Hamner, Neuromuscular Biomechanics Lab, Stanford University

Modifying Muscles Using the Open Sim API


Modeling assumptions

Issues that come up with modeling assumptions. How to be strategic about this.

Validating Your Model

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ModelMaking (last edited 2016-05-04 22:06:30 by localhost)